[ONOS-7732] Automating switch workflow

Change-Id: Ie047c34df2278bc2220cade744f51ca6950f48f6
diff --git a/apps/workflow/BUCK b/apps/workflow/BUCK
new file mode 100644
index 0000000..725153a
--- /dev/null
+++ b/apps/workflow/BUCK
@@ -0,0 +1,13 @@
+BUNDLES = [
+    '//apps/workflow/api:onos-apps-workflow-api',
+    '//apps/workflow/model:onos-apps-workflow-model',
+    '//apps/workflow/app:onos-apps-workflow-app',
+]
+
+onos_app(
+    category = 'Utility',
+    description = "Workflow application",
+    included_bundles = BUNDLES,
+    title = 'Workflow',
+    url = 'http://onosproject.org',
+)
diff --git a/apps/workflow/BUILD b/apps/workflow/BUILD
new file mode 100644
index 0000000..e8b6a91
--- /dev/null
+++ b/apps/workflow/BUILD
@@ -0,0 +1,13 @@
+BUNDLES = [
+    "//apps/workflow/api:onos-apps-workflow-api",
+    "//apps/workflow/model:onos-apps-workflow-model",
+    "//apps/workflow/app:onos-apps-workflow-app",
+]
+
+onos_app(
+    category = "Utility",
+    description = "Workflow application",
+    included_bundles = BUNDLES,
+    title = "Workflow",
+    url = "http://onosproject.org",
+)
diff --git a/apps/workflow/api/BUCK b/apps/workflow/api/BUCK
new file mode 100644
index 0000000..c858089
--- /dev/null
+++ b/apps/workflow/api/BUCK
@@ -0,0 +1,11 @@
+COMPILE_DEPS = [
+    '//lib:CORE_DEPS',
+    '//lib:jackson-core',
+    '//lib:jackson-annotations',
+    '//lib:jackson-databind',
+    '//core/store/serializers:onos-core-serializers',
+]
+
+osgi_jar_with_tests(
+    deps = COMPILE_DEPS,
+)
diff --git a/apps/workflow/api/BUILD b/apps/workflow/api/BUILD
new file mode 100644
index 0000000..721e4b9
--- /dev/null
+++ b/apps/workflow/api/BUILD
@@ -0,0 +1,7 @@
+COMPILE_DEPS = CORE_DEPS + KRYO + JACKSON + [
+    "//core/store/serializers:onos-core-serializers",
+]
+
+osgi_jar_with_tests(
+    deps = COMPILE_DEPS,
+)
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/AbstractWorkflow.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/AbstractWorkflow.java
new file mode 100644
index 0000000..5fb8943
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/AbstractWorkflow.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import java.net.URI;
+
+/**
+ * Abstract class for workflow.
+ */
+public abstract class AbstractWorkflow implements Workflow {
+
+    /**
+     * ID of workflow.
+     */
+    private URI id;
+
+    /**
+     * Constructor for AbstractWorkflow.
+     * @param id ID of workflow
+     */
+    protected AbstractWorkflow(URI id) {
+        this.id = id;
+    }
+
+    @Override
+    public URI id() {
+        return id;
+    }
+
+    @Override
+    public WorkflowContext buildContext(Workplace workplace, DataModelTree data) throws WorkflowException {
+        return DefaultWorkflowContext.builder()
+                .workflowId(id)
+                .workplaceName(workplace.name())
+                .data(data)
+                .build();
+    }
+
+    @Override
+    public WorkflowContext buildSystemContext(Workplace workplace, DataModelTree data) throws WorkflowException {
+        return SystemWorkflowContext.systemBuilder()
+                .workflowId(id)
+                .workplaceName(workplace.name())
+                .data(data)
+                .build();
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/AbstractWorklet.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/AbstractWorklet.java
new file mode 100644
index 0000000..b9fb133
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/AbstractWorklet.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+
+import org.onosproject.event.Event;
+
+/**
+ * Abstract class for worklet.
+ */
+public abstract class AbstractWorklet implements Worklet {
+
+    @Override
+    public String tag() {
+        return this.getClass().getName();
+    }
+
+    @Override
+    public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+        throw new WorkflowException("(" + tag() + ").isCompleted should not be called");
+    }
+
+    @Override
+    public boolean isNext(WorkflowContext context) throws WorkflowException {
+        throw new WorkflowException("(" + tag() + ").isNext should not be called");
+    }
+
+    @Override
+    public void timeout(WorkflowContext context) throws WorkflowException {
+        throw new WorkflowException("Timeout happened");
+    }
+}
+
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/BranchWorklet.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/BranchWorklet.java
new file mode 100644
index 0000000..4f91bba
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/BranchWorklet.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+/**
+ * An interface representing branch worklet. Branch worklet is used for branching workflow execution.
+ */
+public interface BranchWorklet extends Worklet {
+
+    @Override
+    default void process(WorkflowContext context) throws WorkflowException {
+        throw new WorkflowException("This workletType.process should not be called");
+    }
+
+    @Override
+    default boolean isNext(WorkflowContext context) throws WorkflowException {
+        throw new WorkflowException("This workletType.isNext should not be called");
+    }
+
+    /**
+     * Returns next worklet class for branching.
+     * @param context workflow context
+     * @return next worklet class
+     * @throws WorkflowException workflow exception
+     */
+    Class<? extends Worklet> next(WorkflowContext context) throws WorkflowException;
+}
+
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/CheckCondition.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/CheckCondition.java
new file mode 100644
index 0000000..7419583
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/CheckCondition.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+
+/**
+ * Static convenience class that help a whether it was invoked correctly(whether its preconditions have been met).
+ * Methods of this class generally accept a boolean expression which is expected to be true.
+ * When false (or null) is passed instead, the Preconditions method throws an workflow exception.
+ */
+public final class CheckCondition {
+
+    /**
+     * Private class of check condition.
+     */
+    private CheckCondition() {
+    }
+
+    /**
+     * Checks the condition, and if it is false, it raises workflow exception with exception message.
+     * @param condition condition to check. A boolean expression is located on here.
+     * @param exceptionMessage exception message for workflow exception
+     * @throws WorkflowException workflow exception
+     */
+    public static void check(boolean condition, String exceptionMessage) throws WorkflowException {
+        if (!condition) {
+            throw new WorkflowException(exceptionMessage);
+        }
+    }
+
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ContextEventMapStore.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ContextEventMapStore.java
new file mode 100644
index 0000000..4b54cf3
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ContextEventMapStore.java
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onosproject.store.service.DocumentPath;
+import org.onosproject.store.service.Versioned;
+
+import java.util.Map;
+import java.util.Set;
+
+/**
+ *  WorkflowContext Event Map Store.
+ */
+public interface ContextEventMapStore {
+
+    /**
+     * Registers workflow context event mapping.
+     * @param eventType the class name of event
+     * @param eventHintSet Set of event hint string value of the event
+     * @param contextName workflow context name
+     * @param programCounterString the program counter of workflow
+     * @throws WorkflowException workflow exception
+     */
+    void registerEventMap(String eventType, Set<String> eventHintSet,
+                          String contextName, String programCounterString) throws WorkflowException;
+
+    /**
+     * Unregisters workflow context event mapping.
+     * @param eventType the class name of event
+     * @param contextName workflow context name
+     * @throws WorkflowException workflow exception
+     */
+    void unregisterEventMap(String eventType,
+                            String contextName) throws WorkflowException;
+
+    /**
+     * Returns workflow context event mapping.
+     * @param eventType the class name of event
+     * @param eventHint vent hint string value of the event
+     * @return Map of workflow context and value (program counter)
+     * @throws WorkflowException workflow exception
+     */
+    Map<String, String> getEventMapByHint(String eventType,
+                                          String eventHint) throws WorkflowException;
+
+    /**
+     * Returns true or false depending on existence of eventMap of given context.
+     * @param contextName name of workflow context
+     * @return Boolean true or false depending on existence of eventMap of given context
+     */
+    boolean isEventMapPresent(String contextName);
+
+    /**
+     * Returns child nodes on document tree path.
+     * @param path document tree path including eventType and Hint
+     * @return children under document tree path
+     * @throws WorkflowException workflow exception
+     */
+    Map<String, Versioned<String>> getChildren(String path) throws WorkflowException;
+
+    /**
+     * Returns document path.
+     * @param path document path string
+     * @return document tree
+     * @throws WorkflowException workflow exception
+     */
+    DocumentPath getDocumentPath(String path) throws WorkflowException;
+
+    /**
+     * Transforms document tree to json tree.
+     * @return json tree
+     * @throws WorkflowException workflow exception
+     */
+    ObjectNode asJsonTree() throws WorkflowException;
+}
+
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DataModelPointer.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DataModelPointer.java
new file mode 100644
index 0000000..271ce4f
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DataModelPointer.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+/**
+ * Common data model tree path.
+ */
+public interface DataModelPointer {
+
+    /**
+     * Workplace array pointer.
+     */
+    String WORKPLACES_PTR = "/workplaces";
+
+    /**
+     * Workplace name pointer.
+     */
+    String WORKPLACE_NAME_PTR = "/name";
+
+    /**
+     * Workplace data pointer.
+     */
+    String WORKPLACE_DATA_PTR = "/data";
+
+    /**
+     * Workplace workflow pointer.
+     */
+    String WORKPLACE_WORKFLOWS_PTR = "/workflows";
+
+    /**
+     * Workflow op pointer.
+     */
+    String WORKFLOW_OP_PTR = "/op";
+
+    /**
+     * Workflow id pointer.
+     */
+    String WORKFLOW_ID_PTR = "/id";
+
+    /**
+     * Workflow data pointer.
+     */
+    String WORKFLOW_DATA_PTR = "/data";
+
+    /**
+     * Gets path string.
+     * @return path string
+     */
+    String getPath();
+}
+
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DataModelTree.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DataModelTree.java
new file mode 100644
index 0000000..f7ada8d
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DataModelTree.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+/**
+ * Interface for data model tree.
+ */
+public interface DataModelTree {
+
+    /**
+     * Data model tree node type (map or array).
+     */
+    enum Nodetype {
+
+        /**
+         * Map type data model tree node.
+         */
+        MAP,
+
+        /**
+         * Array type data model tree node.
+         */
+        ARRAY
+    }
+
+    /**
+     * Returns subtree on the path.
+     * @param path data model tree path
+     * @return subtree on the path
+     */
+    DataModelTree subtree(String path);
+
+    /**
+     * Attaches subtree on the path.
+     * @param path data model tree path where subtree will be attached
+     * @param tree subtree to be attached
+     * @throws WorkflowException workflow exception
+     */
+    void attach(String path, DataModelTree tree) throws WorkflowException;
+
+    /**
+     * Allocates leaf node on the path.
+     * @param path data model tree path where new leaf node will be allocated
+     * @param leaftype leaf node type
+     * @return data model tree
+     * @throws WorkflowException workflow exception
+     */
+    DataModelTree alloc(String path, Nodetype leaftype) throws WorkflowException;
+
+    /**
+     * Remove node on the path.
+     * @param path data model tree path
+     * @throws WorkflowException workflow exception
+     */
+    void remove(String path) throws WorkflowException;
+}
+
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultRpcDescription.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultRpcDescription.java
new file mode 100644
index 0000000..6f9d3c3
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultRpcDescription.java
@@ -0,0 +1,183 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.MissingNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+import com.google.common.base.MoreObjects;
+
+import static org.onosproject.workflow.api.CheckCondition.check;
+
+/**
+ * Class of workflow RPC description.
+ */
+public final class DefaultRpcDescription implements RpcDescription {
+
+    /**
+     * Workflow RPC operation.
+     */
+    private final String op;
+
+    /**
+     * Parameters.
+     */
+    private final JsonNode params;
+
+    /**
+     * Invocation ID.
+     */
+    private final String id;
+
+    /**
+     * Constructor of workplace description.
+     * @param builder workplace builder
+     */
+    private DefaultRpcDescription(Builder builder) {
+        this.op = builder.op;
+        this.params = builder.params;
+        this.id = builder.id;
+    }
+
+    @Override
+    public String op() {
+        return this.op;
+    }
+
+    @Override
+    public JsonNode params() {
+        return this.params;
+    }
+
+    @Override
+    public String id() {
+        return this.id;
+    }
+
+    /**
+     * Creating workflow RPC description from json tree.
+     * @param root root node for workflow RPC description
+     * @return workflow RPC description
+     * @throws WorkflowException workflow exception
+     */
+    public static DefaultRpcDescription valueOf(JsonNode root) throws WorkflowException {
+
+        JsonNode node = root.at(RPC_OP_PTR);
+        if (!(node instanceof TextNode)) {
+            throw new WorkflowException("invalid RPC operation for " + root);
+        }
+        String rpcOp = node.asText();
+
+        node = root.at(RPC_PARAMS_PTR);
+        if (node instanceof MissingNode) {
+            throw new WorkflowException("invalid RPC parameters for " + root);
+        }
+        JsonNode rpcParams = node;
+
+        node = root.at(RPC_ID_PTR);
+        if (!(node instanceof TextNode)) {
+            throw new WorkflowException("invalid RPC invocation ID for " + root);
+        }
+        String rpcId = node.asText();
+
+
+        return builder()
+                .setOp(rpcOp)
+                .setParams(rpcParams)
+                .setId(rpcId)
+                .build();
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("op", op())
+                .add("params", params())
+                .add("id", id())
+                .toString();
+    }
+
+    /**
+     * Gets builder instance.
+     * @return builder instance
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Builder for workplace RPC description.
+     */
+    public static class Builder {
+
+        /**
+         * Workflow RPC operation.
+         */
+        private String op;
+
+        /**
+         * Parameters.
+         */
+        private JsonNode params;
+
+        /**
+         * Invocation ID.
+         */
+        private String id;
+
+        /**
+         * Sets workflow RPC operation.
+         * @param op workflow RPC operation
+         * @return builder
+         */
+        public Builder setOp(String op) {
+            this.op = op;
+            return this;
+        }
+
+        /**
+         * Sets workflow RPC parameters.
+         * @param params workflow RPC parameters
+         * @return builder
+         */
+        public Builder setParams(JsonNode params) {
+            this.params = params;
+            return this;
+        }
+
+        /**
+         * Sets workflow RPC invocation ID.
+         * @param id workflow invocation ID
+         * @return builder
+         */
+        public Builder setId(String id) {
+            this.id = id;
+            return this;
+        }
+
+        /**
+         * Builds workplace RPC description from builder.
+         * @return instance of workflow RPC description
+         * @throws WorkflowException workflow exception
+         */
+        public DefaultRpcDescription build() throws WorkflowException {
+            check(op != null, "op is invalid");
+            check(params != null, "params is invalid");
+            check(id != null, "id is invalid");
+            return new DefaultRpcDescription(this);
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkflowContext.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkflowContext.java
new file mode 100644
index 0000000..8f5d3c7
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkflowContext.java
@@ -0,0 +1,338 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.google.common.base.MoreObjects;
+import org.onlab.osgi.DefaultServiceDirectory;
+import org.onlab.osgi.ServiceNotFoundException;
+import org.onosproject.event.Event;
+
+import java.net.URI;
+import java.util.HashSet;
+import java.util.Set;
+
+import static org.onosproject.workflow.api.CheckCondition.check;
+
+/**
+ * Default implementation of WorkflowContext.
+ */
+public class DefaultWorkflowContext extends WorkflowContext {
+
+    /**
+     * ID of workflow.
+     */
+    private URI workflowId;
+
+    /**
+     * Workplace name of the workflow.
+     */
+    private String workplaceName;
+
+    /**
+     * State of workflow.
+     */
+    private WorkflowState state;
+
+    /**
+     * Current program counter of the workflow.
+     */
+    private ProgramCounter current;
+
+    /**
+     * Cause of workflow exception.
+     */
+    private String cause;
+
+    /**
+     * Completion event type.
+     */
+    private transient Class<? extends Event> completionEventType;
+
+    /**
+     * Completion event hint Set.
+     */
+    private transient Set<String> completionEventHintSet;
+
+    /**
+     * Completion event generator method reference.
+     */
+    private transient WorkExecutor completionEventGenerator;
+
+    /**
+     * Completion event timeout milliseconds.
+     */
+    private transient long completionEventTimeoutMs;
+
+    /**
+     * Service reference for workflow service.
+     */
+    private transient WorkflowExecutionService workflowExecutionService;
+
+    /**
+     * Service reference for workflow store.
+     */
+    private transient WorkflowStore workflowStore;
+
+    /**
+     * Service reference for workplace store.
+     */
+    private transient WorkplaceStore workplaceStore;
+
+    /**
+     * Constructor of DefaultWorkflowContext.
+     * @param builder default workflow context builder
+     */
+    protected DefaultWorkflowContext(Builder builder) {
+        super(builder.data);
+        this.workflowId = builder.workflowId;
+        this.workplaceName = builder.workplaceName;
+        this.state = WorkflowState.IDLE;
+        this.current = ProgramCounter.INIT_PC;
+    }
+
+    /**
+     * DefaultWorkflowContext name builder.
+     * @param workflowid workflow id
+     * @param workplacename workplace name
+     * @return DefaultWorkflowContext name
+     */
+    public static String nameBuilder(URI workflowid, String workplacename) {
+        return workflowid.toString() + "@" + workplacename;
+    }
+
+    @Override
+    public String name() {
+        return nameBuilder(workflowId, workplaceName);
+    }
+
+    @Override
+    public String distributor() {
+        return workplaceName();
+    }
+
+    @Override
+    public URI workflowId() {
+        return this.workflowId;
+    }
+
+    @Override
+    public String workplaceName() {
+        return workplaceName;
+    }
+
+    @Override
+    public WorkflowState state() {
+        return state;
+    }
+
+    @Override
+    public void setState(WorkflowState state) {
+        this.state = state;
+    }
+
+    @Override
+    public ProgramCounter current() {
+        return this.current;
+    }
+
+    @Override
+    public void setCurrent(ProgramCounter pc) {
+        this.current = pc;
+    }
+
+    @Override
+    public String cause() {
+        return this.cause;
+    }
+
+    @Override
+    public void setCause(String cause) {
+        this.cause = cause;
+    }
+
+    @Override
+    public void completed() {
+        setTriggerNext(true);
+    }
+
+    @Override
+    public void waitCompletion(Class<? extends Event> eventType, String eventHint,
+                               WorkExecutor eventGenerator, long timeoutMs) {
+        this.completionEventType = eventType;
+        this.completionEventHintSet = new HashSet<>();
+        this.completionEventHintSet.add(eventHint);
+        this.completionEventGenerator = eventGenerator;
+        this.completionEventTimeoutMs = timeoutMs;
+    }
+
+    @Override
+    public void waitAnyCompletion(Class<? extends Event> eventType, Set<String> eventHint,
+                               WorkExecutor eventGenerator, long timeoutMs) {
+        this.completionEventType = eventType;
+        this.completionEventHintSet = new HashSet<>();
+        this.completionEventHintSet.addAll(eventHint);
+        this.completionEventGenerator = eventGenerator;
+        this.completionEventTimeoutMs = timeoutMs;
+    }
+
+    @Override
+    public void waitFor(long timeoutMs) {
+        this.completionEventTimeoutMs = timeoutMs;
+    }
+
+    @Override
+    public Class<? extends Event> completionEventType() {
+        return completionEventType;
+    }
+
+    @Override
+    public Set<String> completionEventHints() {
+        return completionEventHintSet;
+    }
+
+    @Override
+    public WorkExecutor completionEventGenerator() {
+        return completionEventGenerator;
+    }
+
+    @Override
+    public long completionEventTimeout() {
+        return completionEventTimeoutMs;
+    }
+
+    @Override
+    public void setWorkflowExecutionService(WorkflowExecutionService workflowExecutionService) {
+        this.workflowExecutionService = workflowExecutionService;
+    }
+
+    @Override
+    public WorkflowExecutionService workflowService() {
+        return workflowExecutionService;
+    }
+
+    @Override
+    public void setWorkflowStore(WorkflowStore workflowStore) {
+        this.workflowStore = workflowStore;
+    }
+
+    @Override
+    public WorkflowStore workflowStore() {
+        return workflowStore;
+    }
+
+    @Override
+    public void setWorkplaceStore(WorkplaceStore workplaceStore) {
+        this.workplaceStore = workplaceStore;
+    }
+
+    @Override
+    public WorkplaceStore workplaceStore() {
+        return workplaceStore;
+    }
+
+    public <T> T getService(Class<T> serviceClass) throws WorkflowException {
+        T service;
+        try {
+            service = DefaultServiceDirectory.getService(serviceClass);
+        } catch (ServiceNotFoundException e) {
+            throw new WorkflowException(e);
+        }
+        return service;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("name", name())
+                .add("triggernext", triggerNext())
+                .add("data", data())
+                .add("current", current)
+                .add("state", state())
+                .add("cause", cause())
+                .toString();
+    }
+
+    /**
+     * Gets builder instance.
+     * @return builder instance
+     */
+    public static final Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Builder for default workflow context.
+     */
+    public static class Builder {
+
+        /**
+         * ID of workflow.
+         */
+        private URI workflowId;
+
+        /**
+         * Workplace name of the workflow.
+         */
+        private String workplaceName;
+
+        /**
+         * Data model tree.
+         */
+        private DataModelTree data;
+
+        /**
+         * Sets workflow id.
+         * @param workflowId workflow id
+         * @return builder
+         */
+        public Builder workflowId(URI workflowId) {
+            this.workflowId = workflowId;
+            return this;
+        }
+
+        /**
+         * Sets workplace name.
+         * @param workplaceName workplace name
+         * @return builder
+         */
+        public Builder workplaceName(String workplaceName) {
+            this.workplaceName = workplaceName;
+            return this;
+        }
+
+        /**
+         * Sets data model tree.
+         * @param data data model tree
+         * @return builder
+         */
+        public Builder data(DataModelTree data) {
+            this.data = data;
+            return this;
+        }
+
+        /**
+         * Builds default workflow context.
+         * @return instance of default workflow context
+         * @throws WorkflowException workflow exception
+         */
+        public DefaultWorkflowContext build() throws WorkflowException {
+            check(data != null, "Invalid data model tree");
+            check(workflowId != null, "Invalid workflowId");
+            check(workplaceName != null, "Invalid workplaceName");
+            return new DefaultWorkflowContext(this);
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkflowDescription.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkflowDescription.java
new file mode 100644
index 0000000..13a8f46
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkflowDescription.java
@@ -0,0 +1,215 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.MissingNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+import com.google.common.base.MoreObjects;
+
+import java.net.URI;
+
+import static org.onosproject.workflow.api.CheckCondition.check;
+
+
+/**
+ * Class for default workflow description.
+ */
+public final class DefaultWorkflowDescription implements WorkflowDescription {
+
+    /**
+     * Workplace Name.
+     */
+    private String workplaceName;
+
+    /**
+     * Workflow ID.
+     */
+    private URI id;
+
+    /**
+     * Workflow data model.
+     */
+    private JsonNode data;
+
+    /**
+     * Constructor of workflow description.
+     * @param builder workflow description builder
+     */
+    private DefaultWorkflowDescription(Builder builder) {
+        this.workplaceName = builder.workplaceName;
+        this.id = builder.id;
+        this.data = builder.data;
+    }
+
+    @Override
+    public String workplaceName() {
+        return this.workplaceName;
+    }
+
+    @Override
+    public URI id() {
+        return this.id;
+    }
+
+    @Override
+    public String workflowContextName() {
+        return DefaultWorkflowContext.nameBuilder(id(), workplaceName());
+    }
+
+    @Override
+    public JsonNode data() {
+        return this.data;
+    }
+
+    /**
+     * Creating workflow description from json tree.
+     * @param root root node for workflow description
+     * @return workflow description
+     * @throws WorkflowException workflow exception
+     */
+    public static DefaultWorkflowDescription valueOf(JsonNode root) throws WorkflowException {
+
+        JsonNode node = root.at(ptr(WF_WORKPLACE));
+        if (!(node instanceof TextNode)) {
+            throw new WorkflowException("invalid workflow workplace for " + root);
+        }
+        String wfWorkplaceName = node.asText();
+
+        node = root.at(ptr(WF_ID));
+        if (!(node instanceof TextNode)) {
+            throw new WorkflowException("invalid workflow id for " + root);
+        }
+        URI wfId = URI.create(node.asText());
+
+        node = root.at(ptr(WF_DATA));
+        if (node instanceof MissingNode) {
+            throw new WorkflowException("invalid workflow data for " + root);
+        }
+        JsonNode wfData = node;
+
+        return builder()
+                .workplaceName(wfWorkplaceName)
+                .id(wfId)
+                .data(wfData)
+                .build();
+    }
+
+    private static String ptr(String field) {
+        return "/" + field;
+    }
+
+    @Override
+    public JsonNode toJson() {
+        ObjectNode root = JsonNodeFactory.instance.objectNode();
+        root.put(WF_WORKPLACE, workplaceName());
+        root.put(WF_ID, id().toString());
+        root.put(WF_DATA, data());
+        return root;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("workplace", workplaceName())
+                .add("id", id())
+                .add("data", data())
+                .toString();
+    }
+
+    /**
+     * Gets builder instance.
+     * @return builder instance
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Builder for workflow description.
+     */
+    public static class Builder {
+
+        /**
+         * Workplace name.
+         */
+        private String workplaceName;
+
+        /**
+         * Workflow ID.
+         */
+        private URI id;
+
+        /**
+         * Workflow data model.
+         */
+        private JsonNode data;
+
+        /**
+         * Sets workplace name.
+         * @param workplaceName workplace name
+         * @return builder
+         */
+        public Builder workplaceName(String workplaceName) {
+            this.workplaceName = workplaceName;
+            return this;
+        }
+
+        /**
+         * Sets workflow id.
+         * @param id workflow ID
+         * @return builder
+         */
+        public Builder id(URI id) {
+            this.id = id;
+            return this;
+        }
+
+        /**
+         * Sets workflow id.
+         * @param id workflow ID string
+         * @return builder
+         */
+        public Builder id(String id) {
+            this.id = URI.create(id);
+            return this;
+        }
+
+        /**
+         * Sets workflow data model.
+         * @param data workflow data model
+         * @return builder
+         */
+        public Builder data(JsonNode data) {
+            this.data = data;
+            return this;
+        }
+
+        /**
+         * Builds workflow description from builder.
+         * @return instance of workflow description
+         * @throws WorkflowException workflow exception
+         */
+        public DefaultWorkflowDescription build() throws WorkflowException {
+            check(workplaceName != null, "workplaceName is invalid");
+            check(id != null, "id is invalid");
+            check(data != null, "data is invalid");
+            return new DefaultWorkflowDescription(this);
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkplace.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkplace.java
new file mode 100644
index 0000000..1c60eaf
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkplace.java
@@ -0,0 +1,92 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.google.common.base.MoreObjects;
+import org.onlab.osgi.DefaultServiceDirectory;
+import org.onlab.osgi.ServiceNotFoundException;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.stream.Collectors;
+
+/**
+ * Default implementation of workplace.
+ */
+public class DefaultWorkplace extends Workplace {
+
+    /**
+     * Name of workplace.
+     */
+    private String name;
+
+    /**
+     * Constructor of DefaultWorkplace.
+     * @param name name of workplace
+     * @param data data model tree
+     */
+    public DefaultWorkplace(String name, DataModelTree data) {
+        super(data);
+        this.name = name;
+    }
+
+    @Override
+    public String name() {
+        return this.name;
+    }
+
+    @Override
+    public String distributor() {
+        return name();
+    }
+
+    @Override
+    public Collection<WorkflowContext> getContexts() throws WorkflowException {
+        WorkplaceStore workplaceStore;
+        try {
+            workplaceStore = DefaultServiceDirectory.getService(WorkplaceStore.class);
+        } catch (ServiceNotFoundException e) {
+            throw new WorkflowException(e);
+        }
+
+        return workplaceStore.getWorkplaceContexts(name());
+    }
+
+    /**
+     * Returns collection of context names.
+     * @return collection of context names
+     */
+    private Collection<String> getContextNames() {
+        Collection<WorkflowContext> ctx;
+        try {
+            ctx = getContexts();
+        } catch (WorkflowException e) {
+            ctx = Collections.emptyList();
+        }
+
+        return ctx.stream().map(x -> x.name()).collect(Collectors.toList());
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("name", name())
+                .add("triggernext", triggerNext())
+                .add("context", data())
+                .add("contexts", getContextNames())
+                .toString();
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkplaceDescription.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkplaceDescription.java
new file mode 100644
index 0000000..e8125f7
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/DefaultWorkplaceDescription.java
@@ -0,0 +1,173 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.MissingNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+import com.google.common.base.MoreObjects;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+
+import static org.onosproject.workflow.api.CheckCondition.check;
+
+/**
+ * Class for default workplace description.
+ */
+public final class DefaultWorkplaceDescription implements WorkplaceDescription {
+
+    /**
+     * Name of workplace.
+     */
+    private final String name;
+
+    /**
+     * Data model of workplace(Optional).
+     */
+    private final Optional<JsonNode> optData;
+
+    /**
+     * Constructor of workplace description.
+     * @param builder workplace builder
+     */
+    private DefaultWorkplaceDescription(Builder builder) {
+        this.name = builder.name;
+        this.optData = builder.optData;
+    }
+
+    @Override
+    public String name() {
+        return this.name;
+    }
+
+    @Override
+    public Optional<JsonNode> data() {
+        return this.optData;
+    }
+
+    /**
+     * Creating workplace description from json tree.
+     * @param root root node for workplace description
+     * @return workplace description
+     * @throws WorkflowException workflow exception
+     */
+    public static DefaultWorkplaceDescription valueOf(JsonNode root) throws WorkflowException {
+
+        JsonNode node = root.at(ptr(WP_NAME));
+        if (!(node instanceof TextNode)) {
+            throw new WorkflowException("invalid workplace name for " + root);
+        }
+
+        Builder builder = builder()
+            .name(node.asText());
+
+        node = root.at(ptr(WP_DATA));
+        if (node != null && !(node instanceof MissingNode)) {
+            if (!(node instanceof ObjectNode) && !(node instanceof ArrayNode)) {
+                throw new WorkflowException("invalid workplace data for " + root);
+            }
+            builder.data(node);
+        }
+
+        return builder.build();
+    }
+
+    private static String ptr(String field) {
+        return "/" + field;
+    }
+
+    @Override
+    public JsonNode toJson() {
+        ObjectNode root = JsonNodeFactory.instance.objectNode();
+        root.put(WP_NAME, name());
+        if (data().isPresent()) {
+            root.put(WP_DATA, data().get());
+        }
+        return root;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("name", name())
+                .add("optData", data())
+                .toString();
+    }
+
+    /**
+     * Gets builder instance.
+     * @return builder instance
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Builder for workplace description.
+     */
+    public static class Builder {
+
+        /**
+         * Workplace name.
+         */
+        private String name;
+
+        /**
+         * Workplace optData model.
+         */
+        private Optional<JsonNode> optData = Optional.empty();
+
+        /**
+         * List of workflow.
+         */
+        private List<DefaultWorkflowDescription> workflowDescs = new ArrayList<DefaultWorkflowDescription>();
+
+        /**
+         * Sets workplace name.
+         * @param name workplace name
+         * @return builder
+         */
+        public Builder name(String name) {
+            this.name = name;
+            return this;
+        }
+
+        /**
+         * Sets optData model.
+         * @param data workplace optData model
+         * @return builder
+         */
+        public Builder data(JsonNode data) {
+            this.optData = Optional.of(data);
+            return this;
+        }
+
+        /**
+         * Builds workplace description from builder.
+         * @return instance of workflow description
+         * @throws WorkflowException workflow exception
+         */
+        public DefaultWorkplaceDescription build() throws WorkflowException {
+            check(name != null, "name is invalid");
+            return new DefaultWorkplaceDescription(this);
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/EventHintSupplier.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/EventHintSupplier.java
new file mode 100644
index 0000000..076bfc0
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/EventHintSupplier.java
@@ -0,0 +1,26 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import org.onosproject.event.Event;
+
+/**
+ * Functional interface for delivering event hint supplier.
+ */
+@FunctionalInterface
+public interface EventHintSupplier {
+    String apply(Event event) throws Throwable;
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/EventTask.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/EventTask.java
new file mode 100644
index 0000000..c2af3e6
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/EventTask.java
@@ -0,0 +1,168 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.google.common.base.MoreObjects;
+import org.onosproject.event.Event;
+
+import java.util.Objects;
+
+import static org.onosproject.workflow.api.CheckCondition.check;
+
+/**
+ * Class for event task.
+ */
+public final class EventTask extends HandlerTask {
+
+    /**
+     * Event triggering event task.
+     */
+    private final Event event;
+
+    /**
+     * Event hint value for finding target event.
+     */
+    private final String eventHint;
+
+    /**
+     * Constructor of event task.
+     * @param builder builder of event task
+     */
+    private EventTask(Builder builder) {
+        super(builder);
+        this.event = builder.event;
+        this.eventHint = builder.eventHint;
+    }
+
+    /**
+     * Gets event of event task.
+     * @return event triggering event task
+     */
+    public Event event() {
+        return event;
+    }
+
+    /**
+     * Gets event type (class name of event) of event task.
+     * @return event type
+     */
+    public String eventType() {
+        return event.getClass().getName();
+    }
+
+    /**
+     * Gets event hint of event task.
+     * @return event hint string
+     */
+    public String eventHint() {
+        return eventHint;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.toString());
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == this) {
+            return true;
+        }
+        if (!(obj instanceof EventTask)) {
+            return false;
+        }
+        return Objects.equals(this.event(), ((EventTask) obj).event())
+                && Objects.equals(this.eventType(), ((EventTask) obj).eventType())
+                && Objects.equals(this.eventHint(), ((EventTask) obj).eventHint());
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("context", context())
+                .add("programCounter", programCounter())
+                .add("event", event())
+                .add("eventHint", eventHint())
+                .toString();
+    }
+
+    /**
+     * Gets a instance of builder.
+     * @return instance of builder
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Builder of EventTask.
+     */
+    public static class Builder extends HandlerTask.Builder {
+
+        /**
+         * Event triggering event task.
+         */
+        private Event event;
+
+        /**
+         * Event hint value for finding target event.
+         */
+        private String eventHint;
+
+        /**
+         * Sets event.
+         * @param event event triggering event task
+         * @return Builder of EventTask
+         */
+        public Builder event(Event event) {
+            this.event = event;
+            return this;
+        }
+
+        /**
+         * Sets event hint.
+         * @param eventHint event hint value for finding target event
+         * @return Builder of EventTask
+         */
+        public Builder eventHint(String eventHint) {
+            this.eventHint = eventHint;
+            return this;
+        }
+
+        @Override
+        public Builder context(WorkflowContext context) {
+            super.context(context);
+            return this;
+        }
+
+        @Override
+        public Builder programCounter(ProgramCounter programCounter) {
+            super.programCounter(programCounter);
+            return this;
+        }
+
+        /**
+         * Builds EventTask.
+         * @return instance of EventTask
+         * @throws WorkflowException workflow exception
+         */
+        public EventTask build() throws WorkflowException {
+            check(event != null, "event is invalid");
+            check(eventHint != null, "eventHint is invalid");
+            return new EventTask(this);
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/EventTimeoutTask.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/EventTimeoutTask.java
new file mode 100644
index 0000000..2ee2672
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/EventTimeoutTask.java
@@ -0,0 +1,159 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.google.common.base.MoreObjects;
+
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+import static org.onosproject.workflow.api.CheckCondition.check;
+
+/**
+ * Class for event timeout task.
+ */
+public final class EventTimeoutTask extends HandlerTask {
+
+    /**
+     * Event type (Class name of event).
+     */
+    private final String eventType;
+
+    /**
+     * Set of Event hint value for finding target event.
+     */
+    private final Set<String> eventHintSet = new HashSet<>();
+
+    /**
+     * Constructor of EventTimeoutTask.
+     * @param builder builder of EventTimeoutTask
+     */
+    private EventTimeoutTask(Builder builder) {
+        super(builder);
+        this.eventType = builder.eventType;
+        this.eventHintSet.addAll(builder.eventHintSet);
+    }
+
+    /**
+     * Gets event type (Class name of event).
+     * @return event type
+     */
+    public String eventType() {
+        return eventType;
+    }
+
+    /**
+     * Gets set of event hint value for finding target event.
+     * @return event hint set
+     */
+    public Set<String> eventHintSet() {
+        return eventHintSet;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.toString());
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == this) {
+            return true;
+        }
+        if (!(obj instanceof EventTask)) {
+            return false;
+        }
+        return Objects.equals(this.eventType(), ((EventTask) obj).eventType())
+                && Objects.equals(this.eventHintSet(), ((EventTask) obj).eventHint());
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("context", context())
+                .add("programCounter", programCounter())
+                .add("eventType", eventType())
+                .add("eventHint", eventHintSet())
+                .toString();
+    }
+
+    /**
+     * Gets a instance of builder.
+     * @return instance of builder
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Builder of EventTimeoutTask.
+     */
+    public static class Builder extends HandlerTask.Builder {
+        /**
+         * Event type (Class name of event).
+         */
+        private String eventType;
+
+        /**
+         * Set of Event hint value for finding target event.
+         */
+        private Set<String> eventHintSet;
+
+        /**
+         * Sets Event type (Class name of event).
+         * @param eventType event type
+         * @return builder of EventTimeoutTask
+         */
+        public Builder eventType(String eventType) {
+            this.eventType = eventType;
+            return this;
+        }
+
+        /**
+         * Sets event hint string for finding target event.
+         * @param eventHintSet Set of event hint string
+         * @return builder of EventTimeoutTask
+         */
+        public Builder eventHintSet(Set<String> eventHintSet) {
+            this.eventHintSet = eventHintSet;
+            return this;
+        }
+
+        @Override
+        public Builder context(WorkflowContext context) {
+            super.context(context);
+            return this;
+        }
+
+        @Override
+        public Builder programCounter(ProgramCounter programCounter) {
+            super.programCounter(programCounter);
+            return this;
+        }
+
+        /**
+         * Builds EventTimeoutTask.
+         * @return instance of EventTimeoutTask
+         * @throws WorkflowException workflow exception
+         */
+        public EventTimeoutTask build() throws WorkflowException {
+            check(eventType != null, "eventType is invalid");
+            check(eventHintSet != null, "eventHintSet is invalid");
+            return new EventTimeoutTask(this);
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/HandlerTask.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/HandlerTask.java
new file mode 100644
index 0000000..94203bc
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/HandlerTask.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * Abstract class for handler task.
+ */
+public abstract class HandlerTask {
+
+    /**
+     * Workflow context of handler task.
+     */
+    private final WorkflowContext context;
+
+    /**
+     * Program counter of handler task.
+     */
+    private final ProgramCounter programCounter;
+
+    /**
+     * Constructor for handler task.
+     * @param builder handler task builder
+     */
+    protected HandlerTask(Builder builder) {
+        this.context = builder.context;
+        this.programCounter = builder.programCounter;
+    }
+
+    /**
+     * Returns workflow context of this handler task.
+     * @return workflow context
+     */
+    public WorkflowContext context() {
+        return context;
+    }
+
+    /**
+     * Returns program counter of this handler task.
+     * @return program counter
+     */
+    public ProgramCounter programCounter() {
+        return programCounter;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("context", context())
+                .add("programCounter", programCounter())
+                .toString();
+    }
+
+    /**
+     * Builder of HandlerTask.
+     */
+    public static class Builder {
+        protected WorkflowContext context;
+        protected ProgramCounter programCounter;
+
+        /**
+         * Sets workflow context of handler task.
+         * @param context workflow context
+         * @return builder of handler task
+         */
+        public Builder context(WorkflowContext context) {
+            this.context = context;
+            return this;
+        }
+
+        /**
+         * Sets program counter of handler task.
+         * @param programCounter program counter of handler type
+         * @return builder of handler task
+         */
+        public Builder programCounter(ProgramCounter programCounter) {
+            this.programCounter = programCounter;
+            return this;
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/HandlerTaskBatchDelegate.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/HandlerTaskBatchDelegate.java
new file mode 100644
index 0000000..c5859f2
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/HandlerTaskBatchDelegate.java
@@ -0,0 +1,32 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import java.util.Collection;
+
+/**
+ * Facade for receiving notifications from the handler task batch service.
+ */
+public interface HandlerTaskBatchDelegate {
+
+    /**
+     * Submits the specified batch of handler task operations for processing.
+     *
+     * @param operations batch of operations
+     */
+    void execute(Collection<Collection<HandlerTask>> operations);
+
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ImmutableListWorkflow.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ImmutableListWorkflow.java
new file mode 100644
index 0000000..ec2be65
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ImmutableListWorkflow.java
@@ -0,0 +1,332 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
+import org.onlab.osgi.DefaultServiceDirectory;
+import org.onlab.osgi.ServiceNotFoundException;
+
+import java.lang.reflect.Modifier;
+import java.net.URI;
+import java.util.List;
+import java.util.Objects;
+import java.util.Set;
+
+import static org.onosproject.workflow.api.CheckCondition.check;
+
+/**
+ * Class for immutable list workflow.
+ */
+public final class ImmutableListWorkflow extends AbstractWorkflow {
+
+    /**
+     * Init worklet type(class name of init worklet type).
+     */
+    private String initWorkletType;
+
+    /**
+     * List of worklet.
+     */
+    private List<String> workletTypeList;
+
+    /**
+     * Set of workflow attributes.
+     */
+    private Set<WorkflowAttribute> attributes;
+
+    private static JsonDataModelInjector dataModelInjector = new JsonDataModelInjector();
+
+    /**
+     * Constructor of ImmutableListWorkflow.
+     *
+     * @param builder builder of ImmutableListWorkflow
+     */
+    private ImmutableListWorkflow(Builder builder) {
+        super(builder.id);
+        this.initWorkletType = builder.initWorkletType;
+        workletTypeList = ImmutableList.copyOf(builder.workletTypeList);
+        attributes = ImmutableSet.copyOf(builder.attributes);
+    }
+
+    @Override
+    public Worklet init(WorkflowContext context) throws WorkflowException {
+        if (Objects.isNull(initWorkletType)) {
+            return null;
+        }
+
+        return getWorkletInstance(initWorkletType);
+    }
+
+
+    @Override
+    public ProgramCounter next(WorkflowContext context) throws WorkflowException {
+
+        int cnt = 0;
+
+        ProgramCounter pc = context.current();
+        check(pc != null, "Invalid program counter");
+
+        for (int i = pc.workletIndex(); i < workletTypeList.size(); i++) {
+
+            if (cnt++ > Worklet.MAX_WORKS) {
+                throw new WorkflowException("Maximum worklet execution exceeded");
+            }
+
+            String workletType = workletTypeList.get(i);
+
+            if (Worklet.Common.COMPLETED.tag().equals(workletType)) {
+                return ProgramCounter.valueOf(workletType, i);
+            }
+
+            if (Worklet.Common.INIT.tag().equals(workletType)) {
+                continue;
+            }
+
+            Worklet worklet = getWorkletInstance(workletType);
+            Class workClass = worklet.getClass();
+
+            if (BranchWorklet.class.isAssignableFrom(workClass)) {
+                Class nextClass = ((BranchWorklet) worklet).next(context);
+                if (nextClass == null) {
+                    throw new WorkflowException("Invalid next Worklet for " + workClass);
+                }
+
+                // TODO : it does not support duplicated use of WorkType. It needs to consider label concept
+                int nextIdx = getClassIndex(nextClass);
+                if (nextIdx == -1) {
+                    throw new WorkflowException("Failed to find next " + nextClass + " for " + workClass);
+                }
+
+                i = nextIdx;
+                continue;
+
+            } else {
+                // isNext is read only. It does not perform 'inhale'.
+                dataModelInjector.inject(worklet, context);
+                if (worklet.isNext(context)) {
+                    return ProgramCounter.valueOf(workletType, i);
+                }
+            }
+        }
+        throw new WorkflowException("workflow reached to end but not COMPLETED");
+    }
+
+    @Override
+    public ProgramCounter increased(ProgramCounter pc) throws WorkflowException {
+
+        int increaedIndex = pc.workletIndex() + 1;
+        if (increaedIndex >= workletTypeList.size()) {
+            throw new WorkflowException("Out of bound in program counter(" + pc + ")");
+        }
+
+        String workletType = workletTypeList.get(increaedIndex);
+        return ProgramCounter.valueOf(workletType, increaedIndex);
+    }
+
+    @Override
+    public Worklet getWorkletInstance(String workletType) throws WorkflowException {
+
+        if (Worklet.Common.INIT.tag().equals(workletType)) {
+            return Worklet.Common.INIT;
+        }
+
+        if (Worklet.Common.COMPLETED.tag().equals(workletType)) {
+            return Worklet.Common.COMPLETED;
+        }
+
+        WorkflowStore store;
+        try {
+            store = DefaultServiceDirectory.getService(WorkflowStore.class);
+        } catch (ServiceNotFoundException e) {
+            throw new WorkflowException(e);
+        }
+
+        Class workClass;
+        try {
+            workClass = store.getClass(workletType);
+        } catch (ClassNotFoundException e) {
+            throw new WorkflowException(e);
+        }
+
+        if (!isAllowed(workClass)) {
+            throw new WorkflowException("Not allowed class(" + workClass.getSimpleName() + ")");
+        }
+
+        Worklet worklet;
+        try {
+            worklet = (Worklet) workClass.newInstance();
+        } catch (Exception e) {
+            throw new WorkflowException(e);
+        }
+
+        return worklet;
+    }
+
+    @Override
+    public Set<WorkflowAttribute> attributes() {
+        return ImmutableSet.copyOf(attributes);
+    }
+
+    @Override
+    public List<String> getWorkletTypeList() {
+        return ImmutableList.copyOf(workletTypeList);
+    }
+
+    /**
+     * Gets index of class in worklet type list.
+     *
+     * @param aClass class to get index
+     * @return index of class in worklet type list
+     */
+    private int getClassIndex(Class aClass) {
+        for (int i = 0; i < workletTypeList.size(); i++) {
+            if (Objects.equals(aClass.getName(), workletTypeList.get(i))) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    /**
+     * Checks whether class is allowed class or not.
+     *
+     * @param clazz class to check
+     * @return Check result
+     */
+    private boolean isAllowed(Class clazz) {
+        // non static inner class is not allowed
+        if (clazz.isMemberClass() && !Modifier.isStatic(clazz.getModifiers())) {
+            return false;
+        }
+        // enum is not allowed
+        if (clazz.isEnum()) {
+            return false;
+        }
+        // class should be subclass of Work
+        if (!Worklet.class.isAssignableFrom(clazz)) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.toString());
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == this) {
+            return true;
+        }
+        if (!(obj instanceof EventTask)) {
+            return false;
+        }
+        return Objects.equals(this.id(), ((ImmutableListWorkflow) obj).id())
+                && Objects.equals(this.initWorkletType, ((ImmutableListWorkflow) obj).initWorkletType)
+                && Objects.equals(this.workletTypeList, ((ImmutableListWorkflow) obj).workletTypeList)
+                && Objects.equals(this.attributes, ((ImmutableListWorkflow) obj).attributes);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("id", id())
+                .add("initWorklet", initWorkletType)
+                .add("workList", workletTypeList)
+                .add("attributes", attributes)
+                .toString();
+    }
+
+    /**
+     * Gets a instance of builder.
+     *
+     * @return instance of builder
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Builder of ImmutableListWorkflow.
+     */
+    public static class Builder {
+
+        private URI id;
+        private String initWorkletType;
+        private final List<String> workletTypeList = Lists.newArrayList();
+        private final Set<WorkflowAttribute> attributes = Sets.newHashSet();
+
+        /**
+         * Sets id of immutable list workflow.
+         *
+         * @param uri id of immutable list workflow
+         * @return builder
+         */
+        public Builder id(URI uri) {
+            this.id = uri;
+            workletTypeList.add(Worklet.Common.INIT.tag());
+            return this;
+        }
+
+        /**
+         * Sets init worklet class name of immutable list workflow.
+         *
+         * @param workletClassName class name of worklet
+         * @return builder
+         */
+        public Builder init(String workletClassName) {
+            this.initWorkletType = workletClassName;
+            return this;
+        }
+
+        /**
+         * Chains worklet class name of immutable list workflow.
+         *
+         * @param workletClassName class name of worklet
+         * @return builder
+         */
+        public Builder chain(String workletClassName) {
+            workletTypeList.add(workletClassName);
+            return this;
+        }
+
+        /**
+         * Adds workflow attribute.
+         *
+         * @param attribute workflow attribute to be added
+         * @return builder
+         */
+        public Builder attribute(WorkflowAttribute attribute) {
+            attributes.add(attribute);
+            return this;
+        }
+
+        /**
+         * Builds ImmutableListWorkflow.
+         *
+         * @return instance of ImmutableListWorkflow
+         */
+        public ImmutableListWorkflow build() {
+            workletTypeList.add(Worklet.Common.COMPLETED.tag());
+            return new ImmutableListWorkflow(this);
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/JsonDataModel.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/JsonDataModel.java
new file mode 100644
index 0000000..fb26642
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/JsonDataModel.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.FIELD)
+@Retention(RetentionPolicy.RUNTIME)
+
+/**
+ * Annotation for injecting json data model on work-let execution context.
+ */
+public @interface JsonDataModel {
+
+    /**
+     * Path of data model.
+     *
+     * @return path of data model
+     */
+    String path() default "/";
+
+    /**
+     * Representing whether this data model is optional or not.
+     *
+     * @return optional or not
+     */
+    boolean optional() default false;
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/JsonDataModelInjector.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/JsonDataModelInjector.java
new file mode 100644
index 0000000..6f87411
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/JsonDataModelInjector.java
@@ -0,0 +1,605 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.BooleanNode;
+import com.fasterxml.jackson.databind.node.IntNode;
+import com.fasterxml.jackson.databind.node.MissingNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * Class for injecting json data model on the work-let execution context.
+ */
+public class JsonDataModelInjector {
+
+    private static final Logger log = LoggerFactory.getLogger(JsonDataModelInjector.class);
+
+    /**
+     * Injects data model to work-let.
+     *
+     * @param worklet work-let to be injected
+     * @param context workflow context
+     * @throws WorkflowException workflow exception
+     */
+    public void inject(Worklet worklet, WorkflowContext context) throws WorkflowException {
+
+        handle(worklet, context, this::injectModel);
+    }
+
+    /**
+     * Inhales data model from work-let.
+     *
+     * @param worklet work-let to be inhaled
+     * @param context workflow context
+     * @throws WorkflowException workflow exception
+     */
+    public void inhale(Worklet worklet, WorkflowContext context) throws WorkflowException {
+
+        handle(worklet, context, this::inhaleModel);
+    }
+
+    private void handle(Worklet worklet, WorkflowContext context, DataModelFieldBehavior func)
+            throws WorkflowException {
+        Class cl = worklet.getClass();
+        List<Field> fields = getInheritedFields(cl);
+        if (Objects.isNull(fields)) {
+            log.error("Invalid fields on {}", cl);
+            return;
+        }
+
+        for (Field field : fields) {
+            Annotation[] annotations = field.getAnnotations();
+            if (Objects.isNull(annotations)) {
+                continue;
+            }
+            for (Annotation annotation : annotations) {
+                if (!(annotation instanceof JsonDataModel)) {
+                    continue;
+                }
+                JsonDataModel model = (JsonDataModel) annotation;
+                func.apply(worklet, context, field, model);
+            }
+        }
+    }
+
+    private static List<Field> getInheritedFields(Class<?> type) {
+        List<Field> fields = new ArrayList<Field>();
+
+        Class<?> cl = type;
+        while (cl != null && cl != Object.class) {
+            for (Field field : cl.getDeclaredFields()) {
+                if (!field.isSynthetic()) {
+                    fields.add(field);
+                }
+            }
+            cl = cl.getSuperclass();
+        }
+        return fields;
+    }
+
+    /**
+     * Functional interface for json data model annotated field behavior.
+     */
+    @FunctionalInterface
+    public interface DataModelFieldBehavior {
+        void apply(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+                throws WorkflowException;
+    }
+
+    private static Map<Class, DataModelFieldBehavior> injectTypeMap = new HashMap<>();
+
+    static {
+        injectTypeMap.put(String.class, JsonDataModelInjector::injectText);
+        injectTypeMap.put(Integer.class, JsonDataModelInjector::injectInteger);
+        injectTypeMap.put(Boolean.class, JsonDataModelInjector::injectBoolean);
+        injectTypeMap.put(JsonNode.class, JsonDataModelInjector::injectJsonNode);
+        injectTypeMap.put(ArrayNode.class, JsonDataModelInjector::injectArrayNode);
+        injectTypeMap.put(ObjectNode.class, JsonDataModelInjector::injectObjectNode);
+    }
+
+    /**
+     * Injects data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private void injectModel(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+
+        DataModelFieldBehavior behavior = injectTypeMap.get(field.getType());
+        if (Objects.isNull(behavior)) {
+            throw new WorkflowException("Not supported type(" + field.getType() + ")");
+        }
+        behavior.apply(worklet, context, field, model);
+    }
+
+    /**
+     * Injects text data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   text data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void injectText(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+
+        String text = ((JsonDataModelTree) context.data()).textAt(model.path());
+        if (Objects.isNull(text)) {
+            if (model.optional()) {
+                return;
+            }
+            throw new WorkflowException("Invalid text data model on (" + model.path() + ")");
+        }
+
+        if (!(Objects.equals(field.getType(), String.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not String");
+        }
+
+        try {
+            field.setAccessible(true);
+            field.set(worklet, text);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+    }
+
+    /**
+     * Injects integer data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   integer data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void injectInteger(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+        Integer number = ((JsonDataModelTree) context.data()).intAt(model.path());
+        if (Objects.isNull(number)) {
+            if (model.optional()) {
+                return;
+            }
+            throw new WorkflowException("Invalid number data model on (" + model.path() + ")");
+        }
+
+        if (!(Objects.equals(field.getType(), Integer.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not Integer");
+        }
+
+        try {
+            field.setAccessible(true);
+            field.set(worklet, number);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+    }
+
+    /**
+     * Injects boolean data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   boolean data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void injectBoolean(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+
+        Boolean bool = ((JsonDataModelTree) context.data()).booleanAt(model.path());
+        if (Objects.isNull(bool)) {
+            if (model.optional()) {
+                return;
+            }
+            throw new WorkflowException("Invalid boolean data model on (" + model.path() + ")");
+        }
+
+        if (!(Objects.equals(field.getType(), Boolean.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not Boolean");
+        }
+
+        try {
+            field.setAccessible(true);
+            field.set(worklet, bool);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+    }
+
+    /**
+     * Injects json node data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   json node data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void injectJsonNode(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+
+        JsonNode jsonNode = ((JsonDataModelTree) context.data()).nodeAt(model.path());
+        if (Objects.isNull(jsonNode)) {
+            if (model.optional()) {
+                return;
+            }
+            throw new WorkflowException("Invalid json node data model on (" + model.path() + ")");
+        }
+
+        if (!(Objects.equals(field.getType(), JsonNode.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not JsonNode");
+        }
+
+        try {
+            field.setAccessible(true);
+            field.set(worklet, jsonNode);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+    }
+
+    /**
+     * Injects json array node data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   json array node data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void injectArrayNode(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+
+        ArrayNode arrayNode = ((JsonDataModelTree) context.data()).arrayAt(model.path());
+        if (Objects.isNull(arrayNode)) {
+            if (model.optional()) {
+                return;
+            }
+            throw new WorkflowException("Invalid array node data model on (" + model.path() + ")");
+        }
+
+        if (!(Objects.equals(field.getType(), ArrayNode.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not ArrayNode");
+        }
+
+        try {
+            field.setAccessible(true);
+            field.set(worklet, arrayNode);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+    }
+
+    /**
+     * Injects json object node data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   json object node data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void injectObjectNode(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+
+        ObjectNode objNode = ((JsonDataModelTree) context.data()).objectAt(model.path());
+        if (Objects.isNull(objNode)) {
+            if (model.optional()) {
+                return;
+            }
+            throw new WorkflowException("Invalid object node data model on (" + model.path() + ")");
+        }
+
+        if (!(Objects.equals(field.getType(), ObjectNode.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not ObjectNode");
+        }
+
+        try {
+            field.setAccessible(true);
+            field.set(worklet, objNode);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+    }
+
+    private static Map<Class, DataModelFieldBehavior> inhaleTypeMap = new HashMap<>();
+
+    static {
+        inhaleTypeMap.put(String.class, JsonDataModelInjector::inhaleText);
+        inhaleTypeMap.put(Integer.class, JsonDataModelInjector::inhaleInteger);
+        inhaleTypeMap.put(Boolean.class, JsonDataModelInjector::inhaleBoolean);
+        inhaleTypeMap.put(JsonNode.class, JsonDataModelInjector::inhaleJsonNode);
+        inhaleTypeMap.put(ArrayNode.class, JsonDataModelInjector::inhaleArrayNode);
+        inhaleTypeMap.put(ObjectNode.class, JsonDataModelInjector::inhaleObjectNode);
+    }
+
+    /**
+     * Inhales data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private void inhaleModel(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+
+        DataModelFieldBehavior behavior = inhaleTypeMap.get(field.getType());
+        if (Objects.isNull(behavior)) {
+            throw new WorkflowException("Not supported type(" + field.getType() + ")");
+        }
+        behavior.apply(worklet, context, field, model);
+    }
+
+    /**
+     * Inhales text data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   text data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void inhaleText(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+
+        if (!(Objects.equals(field.getType(), String.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not String");
+        }
+
+        String text;
+        try {
+            field.setAccessible(true);
+            text = (String) field.get(worklet);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+
+        if (Objects.isNull(text)) {
+            return;
+        }
+
+        JsonDataModelTree tree = (JsonDataModelTree) context.data();
+        JsonNode jsonNode = tree.nodeAt(model.path());
+
+        if (Objects.isNull(jsonNode) || jsonNode instanceof MissingNode) {
+            tree.setAt(model.path(), text);
+        } else if (!(jsonNode instanceof TextNode)) {
+            throw new WorkflowException("Invalid text data model on (" + model.path() + ")");
+        } else {
+            tree.remove(model.path());
+            tree.setAt(model.path(), text);
+        }
+    }
+
+    /**
+     * Inhales integer data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   integer data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void inhaleInteger(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+        if (!(Objects.equals(field.getType(), Integer.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not Integer");
+        }
+
+        Integer number;
+        try {
+            field.setAccessible(true);
+            number = (Integer) field.get(worklet);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+
+        if (Objects.isNull(number)) {
+            return;
+        }
+
+        JsonDataModelTree tree = (JsonDataModelTree) context.data();
+        JsonNode jsonNode = tree.nodeAt(model.path());
+
+        if (Objects.isNull(jsonNode) || jsonNode instanceof MissingNode) {
+            tree.setAt(model.path(), number);
+        } else if (!(jsonNode instanceof IntNode)) {
+            throw new WorkflowException("Invalid integer data model on (" + model.path() + ")");
+        } else {
+            tree.remove(model.path());
+            tree.setAt(model.path(), number);
+        }
+    }
+
+    /**
+     * Inhales boolean data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   boolean data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void inhaleBoolean(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+
+        if (!(Objects.equals(field.getType(), Boolean.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not Boolean");
+        }
+
+        Boolean bool;
+        try {
+            field.setAccessible(true);
+            bool = (Boolean) field.get(worklet);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+
+        if (Objects.isNull(bool)) {
+            return;
+        }
+
+        JsonDataModelTree tree = (JsonDataModelTree) context.data();
+        JsonNode jsonNode = tree.nodeAt(model.path());
+
+        if (Objects.isNull(jsonNode) || jsonNode instanceof MissingNode) {
+            tree.setAt(model.path(), bool);
+        } else if (!(jsonNode instanceof BooleanNode)) {
+            throw new WorkflowException("Invalid boolean data model on (" + model.path() + ")");
+        } else {
+            tree.remove(model.path());
+            tree.setAt(model.path(), bool);
+        }
+    }
+
+    /**
+     * Inhales json node data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   json node data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void inhaleJsonNode(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+
+        if (!(Objects.equals(field.getType(), JsonNode.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not JsonNode");
+        }
+
+        JsonNode tgtJsonNode;
+        try {
+            field.setAccessible(true);
+            tgtJsonNode = (JsonNode) field.get(worklet);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+
+        if (Objects.isNull(tgtJsonNode)) {
+            return;
+        }
+
+        JsonDataModelTree tree = (JsonDataModelTree) context.data();
+        JsonNode jsonNode = tree.nodeAt(model.path());
+
+        if (Objects.isNull(jsonNode) || jsonNode instanceof MissingNode) {
+            tree.attach(model.path(), new JsonDataModelTree(tgtJsonNode));
+        } else if (!(jsonNode instanceof JsonNode)) {
+            throw new WorkflowException("Invalid json node data model on (" + model.path() + ")");
+        } else {
+            // do nothing
+        }
+    }
+
+    /**
+     * Inhales json array node data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   json array node data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void inhaleArrayNode(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+        if (!(Objects.equals(field.getType(), ArrayNode.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not ArrayNode");
+        }
+
+        ArrayNode tgtArrayNode;
+        try {
+            field.setAccessible(true);
+            tgtArrayNode = (ArrayNode) field.get(worklet);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+
+        if (Objects.isNull(tgtArrayNode)) {
+            return;
+        }
+
+        JsonDataModelTree tree = (JsonDataModelTree) context.data();
+        JsonNode jsonNode = tree.nodeAt(model.path());
+
+        if (Objects.isNull(jsonNode) || jsonNode instanceof MissingNode) {
+            tree.attach(model.path(), new JsonDataModelTree(tgtArrayNode));
+        } else if (!(jsonNode instanceof ArrayNode)) {
+            throw new WorkflowException("Invalid array node data model on (" + model.path() + ")");
+        } else {
+            // do nothing
+        }
+    }
+
+    /**
+     * Inhales json object node data model on the filed of work-let.
+     *
+     * @param worklet work-let
+     * @param context workflow context
+     * @param field   the field of work-let
+     * @param model   json object node data model for the field
+     * @throws WorkflowException workflow exception
+     */
+    private static void inhaleObjectNode(Worklet worklet, WorkflowContext context, Field field, JsonDataModel model)
+            throws WorkflowException {
+        if (!(Objects.equals(field.getType(), ObjectNode.class))) {
+            throw new WorkflowException("Target field (" + field + ") is not ObjectNode");
+        }
+
+        ObjectNode tgtObjNode;
+        try {
+            field.setAccessible(true);
+            tgtObjNode = (ObjectNode) field.get(worklet);
+        } catch (IllegalAccessException e) {
+            throw new WorkflowException(e);
+        }
+
+        if (Objects.isNull(tgtObjNode)) {
+            return;
+        }
+
+        JsonDataModelTree tree = (JsonDataModelTree) context.data();
+        JsonNode jsonNode = tree.nodeAt(model.path());
+
+        if (Objects.isNull(jsonNode) || jsonNode instanceof MissingNode) {
+            tree.attach(model.path(), new JsonDataModelTree(tgtObjNode));
+        } else if (!(jsonNode instanceof ObjectNode)) {
+            throw new WorkflowException("Invalid object node data model on (" + model.path() + ")");
+        } else {
+            // do nothing
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/JsonDataModelTree.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/JsonDataModelTree.java
new file mode 100644
index 0000000..7ee1be7
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/JsonDataModelTree.java
@@ -0,0 +1,550 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+
+import com.fasterxml.jackson.core.JsonPointer;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.BooleanNode;
+import com.fasterxml.jackson.databind.node.IntNode;
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.JsonNodeType;
+import com.fasterxml.jackson.databind.node.MissingNode;
+import com.fasterxml.jackson.databind.node.NumericNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+import com.google.common.base.MoreObjects;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Objects;
+
+/**
+ * Class for json data model tree.
+ */
+public final class JsonDataModelTree implements DataModelTree {
+
+    private static final Logger log = LoggerFactory.getLogger(JsonDataModelTree.class);
+
+    /**
+     * Root node of json data model tree.
+     */
+    private JsonNode root;
+
+    /**
+     * Constructor of JsonDataModelTree.
+     */
+    public JsonDataModelTree() {
+        this.root = JsonNodeFactory.instance.objectNode();
+    }
+
+    /**
+     * Constructor of JsonDataModelTree.
+     * @param root root node of json data model tree
+     */
+    public JsonDataModelTree(JsonNode root) {
+        this.root = root;
+    }
+
+    @Override
+    public DataModelTree subtree(String path) {
+        JsonNode node = root.at(path);
+        if (Objects.isNull(node) || node.isMissingNode()) {
+            return null;
+        }
+        return new JsonDataModelTree(node);
+    }
+
+    @Override
+    public void attach(String path, DataModelTree tree) throws WorkflowException {
+
+        if (root == null || root instanceof MissingNode) {
+            throw new WorkflowException("Invalid root node");
+        }
+
+        JsonPointer ptr = JsonPointer.compile(path);
+
+        if (!(tree instanceof JsonDataModelTree)) {
+            throw new WorkflowException("Invalid subTree(" + tree + ")");
+        }
+        JsonNode attachingNode = ((JsonDataModelTree) tree).root();
+
+        attach(ptr, attachingNode);
+    }
+
+    private void attach(JsonPointer ptr, JsonNode attachingNode) throws WorkflowException {
+
+        JsonNode node = root.at(ptr);
+        if (!(node instanceof MissingNode)) {
+            throw new WorkflowException("Path(" + ptr + ") has already subtree(" + node + ")");
+        }
+
+        if (ptr.last().getMatchingIndex() != -1) {
+
+            alloc(ptr.head(), Nodetype.ARRAY);
+            JsonNode parentNode = root.at(ptr.head());
+            if (!parentNode.isArray()) {
+                throw new WorkflowException("Invalid parentNode type(" + parentNode.getNodeType() + " != Array)");
+            }
+            int index = ptr.last().getMatchingIndex();
+            ((ArrayNode) parentNode).insert(index, attachingNode);
+
+        } else if (ptr.last().getMatchingProperty() != null) {
+
+            alloc(ptr.head(), Nodetype.MAP);
+            JsonNode parentNode = root.at(ptr.head());
+            if (!parentNode.isObject()) {
+                throw new WorkflowException("Invalid parentNode type(" + parentNode.getNodeType() + " != Object)");
+            }
+            String key = ptr.last().getMatchingProperty();
+            ((ObjectNode) parentNode).put(key, attachingNode);
+
+        } else {
+            throw new WorkflowException("Invalid path(" + ptr + ")");
+        }
+    }
+
+    @Override
+    public void remove(String path) throws WorkflowException {
+        JsonPointer ptr = JsonPointer.compile(path);
+        remove(ptr);
+    }
+
+    private void remove(JsonPointer ptr) throws WorkflowException {
+
+        JsonNode node = root.at(ptr);
+        if (node instanceof MissingNode) {
+            log.warn("{} does not have valid node", ptr);
+            return;
+        }
+
+        if (ptr.last().getMatchingIndex() != -1) {
+
+            JsonNode parentNode = root.at(ptr.head());
+            if (!parentNode.isArray()) {
+                throw new WorkflowException("Invalid parentNode type(" + parentNode.getNodeType() + " != Array)");
+            }
+            int index = ptr.last().getMatchingIndex();
+            ((ArrayNode) parentNode).remove(index);
+
+        } else if (ptr.last().getMatchingProperty() != null) {
+
+            JsonNode parentNode = root.at(ptr.head());
+            if (!parentNode.isObject()) {
+                throw new WorkflowException("Invalid parentNode type(" + parentNode.getNodeType() + " != Object)");
+            }
+            String key = ptr.last().getMatchingProperty();
+            ((ObjectNode) parentNode).remove(key);
+
+        } else {
+            throw new WorkflowException("Invalid path(" + ptr + ")");
+        }
+    }
+
+    @Override
+    public JsonDataModelTree alloc(String path, Nodetype leaftype) throws WorkflowException {
+        if (root == null || root instanceof MissingNode) {
+            throw new WorkflowException("Invalid root node");
+        }
+
+        JsonPointer ptr = JsonPointer.compile(path);
+        return alloc(ptr, leaftype);
+    }
+
+    /**
+     * Allocates json data model tree on json pointer path with specific leaf type.
+     * @param ptr json pointer to allocate
+     * @param leaftype type of leaf node
+     * @return json data model tree
+     * @throws WorkflowException workflow exception
+     */
+    private JsonDataModelTree alloc(JsonPointer ptr, Nodetype leaftype) throws WorkflowException {
+        if (root == null || root instanceof MissingNode) {
+            throw new WorkflowException("Invalid root node");
+        }
+
+        switch (leaftype) {
+            case MAP:
+                alloc(root, ptr, JsonNodeType.OBJECT);
+                break;
+            case ARRAY:
+                alloc(root, ptr, JsonNodeType.ARRAY);
+                break;
+            default:
+                throw new WorkflowException("Not supported leaftype(" + leaftype + ")");
+        }
+        return this;
+    }
+
+    /**
+     * Gets root json node.
+     * @return root json node
+     * @throws WorkflowException workflow exception
+     */
+    public JsonNode root() throws WorkflowException {
+        return nodeAt("");
+    }
+
+    /**
+     * Gets root json node as ObjectNode (MAP type).
+     * @return root json node as ObjectNode
+     * @throws WorkflowException workflow exception
+     */
+    public ObjectNode rootObject() throws WorkflowException {
+        return objectAt("");
+    }
+
+    /**
+     * Gets root json node as ArrayNode (Array type).
+     * @return root json node as ArrayNode
+     * @throws WorkflowException workflow exception
+     */
+    public ArrayNode rootArray() throws WorkflowException {
+        return arrayAt("");
+    }
+
+    /**
+     * Gets json node on specific path.
+     * @param path path of json node
+     * @return json node on specific path
+     * @throws WorkflowException workflow exception
+     */
+    public JsonNode nodeAt(String path) throws WorkflowException {
+        JsonPointer ptr = JsonPointer.compile(path);
+        return nodeAt(ptr);
+    }
+
+    /**
+     * Gets json node on specific json pointer.
+     * @param ptr json pointer
+     * @return json node on specific json pointer.
+     * @throws WorkflowException workflow exception
+     */
+    public JsonNode nodeAt(JsonPointer ptr) throws WorkflowException {
+        if (root == null || root instanceof MissingNode) {
+            throw new WorkflowException("Invalid root node");
+        }
+        JsonNode node = root.at(ptr);
+        return node;
+    }
+
+    /**
+     * Gets json node on specific path as ObjectNode.
+     * @param path path of json node
+     * @return ObjectNode type json node on specific path
+     * @throws WorkflowException workflow exception
+     */
+    public ObjectNode objectAt(String path) throws WorkflowException {
+        JsonPointer ptr = JsonPointer.compile(path);
+        return objectAt(ptr);
+    }
+
+    /**
+     * Gets json node on specific json pointer as ObjectNode.
+     * @param ptr json pointer
+     * @return ObjectNode type json node on specific json pointer.
+     * @throws WorkflowException workflow exception
+     */
+    public ObjectNode objectAt(JsonPointer ptr) throws WorkflowException {
+        if (root == null || root instanceof MissingNode) {
+            throw new WorkflowException("Invalid root node");
+        }
+        JsonNode node = root.at(ptr);
+        if (node instanceof MissingNode) {
+            return null;
+        }
+        if (!(node instanceof ObjectNode)) {
+            throw new WorkflowException("Invalid node(" + node + ") at " + ptr);
+        }
+        return (ObjectNode) node;
+    }
+
+    /**
+     * Gets json node on specific path as ArrayNode.
+     * @param path path of json node
+     * @return ArrayNode type json node on specific path
+     * @throws WorkflowException workflow exception
+     */
+    public ArrayNode arrayAt(String path) throws WorkflowException {
+        JsonPointer ptr = JsonPointer.compile(path);
+        return arrayAt(ptr);
+    }
+
+    /**
+     * Gets json node on specific json pointer as ArrayNode.
+     * @param ptr json pointer
+     * @return ArrayNode type json node on specific json pointer.
+     * @throws WorkflowException workflow exception
+     */
+    public ArrayNode arrayAt(JsonPointer ptr) throws WorkflowException {
+        if (root == null || root instanceof MissingNode) {
+            throw new WorkflowException("Invalid root node");
+        }
+        JsonNode node = root.at(ptr);
+        if (node instanceof MissingNode) {
+            return null;
+        }
+        if (!(node instanceof ArrayNode)) {
+            throw new WorkflowException("Invalid node(" + node + ") at " + ptr);
+        }
+        return (ArrayNode) node;
+    }
+
+    /**
+     * Gets text node on specific path.
+     * @param path path of json node
+     * @return text on specific path
+     * @throws WorkflowException workflow exception
+     */
+    public String textAt(String path) throws WorkflowException {
+        JsonPointer ptr = JsonPointer.compile(path);
+        return textAt(ptr);
+    }
+
+    /**
+     * Gets text on specific json pointer.
+     * @param ptr json pointer
+     * @return text on specific json pointer
+     * @throws WorkflowException workflow exception
+     */
+    public String textAt(JsonPointer ptr) throws WorkflowException {
+        if (root == null || root instanceof MissingNode) {
+            throw new WorkflowException("Invalid root node");
+        }
+        JsonNode node = root.at(ptr);
+        if (node instanceof MissingNode) {
+            return null;
+        }
+        if (!(node instanceof TextNode)) {
+            throw new WorkflowException("Invalid node(" + node + ") at " + ptr);
+        }
+        return ((TextNode) node).asText();
+    }
+
+    /**
+     * Gets integer node on specific path.
+     * @param path path of json node
+     * @return integer on specific path
+     * @throws WorkflowException workflow exception
+     */
+    public Integer intAt(String path) throws WorkflowException {
+        JsonPointer ptr = JsonPointer.compile(path);
+        return intAt(ptr);
+    }
+
+    /**
+     * Gets integer on specific json pointer.
+     * @param ptr json pointer
+     * @return integer on specific json pointer
+     * @throws WorkflowException workflow exception
+     */
+    public Integer intAt(JsonPointer ptr) throws WorkflowException {
+        if (root == null || root instanceof MissingNode) {
+            throw new WorkflowException("Invalid root node");
+        }
+        JsonNode node = root.at(ptr);
+        if (node instanceof MissingNode) {
+            return null;
+        }
+        if (!(node instanceof NumericNode)) {
+            throw new WorkflowException("Invalid node(" + node + ") at " + ptr);
+        }
+        return ((NumericNode) node).asInt();
+    }
+
+    /**
+     * Gets boolean on specific path.
+     * @param path path of json node
+     * @return boolean on specific path
+     * @throws WorkflowException workflow exception
+     */
+    public Boolean booleanAt(String path) throws WorkflowException {
+        JsonPointer ptr = JsonPointer.compile(path);
+        return booleanAt(ptr);
+    }
+
+    /**
+     * Gets boolean on specific json pointer.
+     * @param ptr json pointer
+     * @return boolean on specific json pointer
+     * @throws WorkflowException workflow exception
+     */
+    public Boolean booleanAt(JsonPointer ptr) throws WorkflowException {
+        if (root == null || root instanceof MissingNode) {
+            throw new WorkflowException("Invalid root node");
+        }
+        JsonNode node = root.at(ptr);
+        if (node instanceof MissingNode) {
+            return null;
+        }
+        if (!(node instanceof BooleanNode)) {
+            throw new WorkflowException("Invalid node(" + node + ") at " + ptr);
+        }
+        return ((BooleanNode) node).asBoolean();
+    }
+
+    /**
+     * Sets text on specific json path.
+     * @param path json path
+     * @param text text to set
+     * @throws WorkflowException workflow exception
+     */
+    public void setAt(String path, String text) throws WorkflowException {
+        JsonPointer ptr = JsonPointer.compile(path);
+        setAt(ptr, text);
+    }
+
+    /**
+     * Sets text on the specific json pointer.
+     * @param ptr json pointer
+     * @param text text to set
+     * @throws WorkflowException workflow exception
+     */
+    public void setAt(JsonPointer ptr, String text) throws WorkflowException {
+        TextNode textNode = TextNode.valueOf(text);
+        attach(ptr, textNode);
+    }
+
+    /**
+     * Sets boolean on specific json path.
+     * @param path json path
+     * @param isTrue boolean to set
+     * @throws WorkflowException workflow exception
+     */
+    public void setAt(String path, Boolean isTrue) throws WorkflowException {
+        JsonPointer ptr = JsonPointer.compile(path);
+        setAt(ptr, isTrue);
+    }
+
+    /**
+     * Sets boolean on the specific json pointer.
+     * @param ptr json pointer
+     * @param isTrue boolean to set
+     * @throws WorkflowException workflow exception
+     */
+    public void setAt(JsonPointer ptr, Boolean isTrue) throws WorkflowException {
+        BooleanNode booleanNode = BooleanNode.valueOf(isTrue);
+        attach(ptr, booleanNode);
+    }
+
+    /**
+     * Sets integer on specific json path.
+     * @param path json path
+     * @param number number to set
+     * @throws WorkflowException workflow exception
+     */
+    public void setAt(String path, Integer number) throws WorkflowException {
+        JsonPointer ptr = JsonPointer.compile(path);
+        setAt(ptr, number);
+    }
+
+    /**
+     * Sets integer on the specific json pointer.
+     * @param ptr json pointer
+     * @param number number to set
+     * @throws WorkflowException workflow exception
+     */
+    public void setAt(JsonPointer ptr, Integer number) throws WorkflowException {
+        IntNode intNode = IntNode.valueOf(number);
+        attach(ptr, intNode);
+    }
+
+    /**
+     * Allocates json data model tree on json pointer path with specific leaf type.
+     * @param node current json node in the json tree path
+     * @param ptr json pointer
+     * @param leaftype leaf type to be allocated
+     * @return allocated json node
+     * @throws WorkflowException workflow exception
+     */
+    private JsonNode alloc(JsonNode node, JsonPointer ptr, JsonNodeType leaftype) throws WorkflowException {
+
+        if (ptr.matches()) {
+            if (node == null || node instanceof MissingNode) {
+                node = createEmpty(leaftype);
+            } else {
+                //TODO: checking existing node type is matched with leaftype
+                if (!Objects.equals(node.getNodeType(), leaftype)) {
+                    throw new WorkflowException("Requesting leaftype(" + leaftype + ") is not matched with "
+                            + "existing nodetype(" + node.getNodeType() + ") for " + ptr);
+                }
+            }
+            return node;
+        }
+
+        if (ptr.getMatchingIndex() != -1) {
+            if (node == null || node instanceof MissingNode) {
+                node = createEmpty(JsonNodeType.ARRAY);
+            }
+            JsonNode child = alloc(node.get(ptr.getMatchingIndex()), ptr.tail(), leaftype);
+            if (!node.has(ptr.getMatchingIndex())) {
+                ((ArrayNode) node).insert(ptr.getMatchingIndex(), child);
+            }
+        } else if (ptr.getMatchingProperty() != null) {
+            if (node == null || node instanceof MissingNode) {
+                node = createEmpty(JsonNodeType.OBJECT);
+            }
+            JsonNode child = alloc(node.get(ptr.getMatchingProperty()), ptr.tail(), leaftype);
+            if (!node.has(ptr.getMatchingProperty())) {
+                ((ObjectNode) node).put(ptr.getMatchingProperty(), child);
+            }
+        }
+        return node;
+    }
+
+    /**
+     * Creating empty json node.
+     * @param type json node type to create
+     * @return created json node
+     * @throws WorkflowException workflow exception
+     */
+    private JsonNode createEmpty(JsonNodeType type) throws WorkflowException {
+        if (type == JsonNodeType.OBJECT) {
+            return JsonNodeFactory.instance.objectNode();
+        } else if (type == JsonNodeType.ARRAY) {
+            return JsonNodeFactory.instance.arrayNode();
+        } else if (type == JsonNodeType.STRING) {
+            return JsonNodeFactory.instance.textNode("");
+        } else {
+            throw new WorkflowException("Not supported JsonNodetype(" + type + ")");
+        }
+    }
+
+    /**
+     * Gets the pretty json formatted string of this json data model tree.
+     * @return pretty json formatted string of this json data model tree
+     */
+    public String formattedRootString() {
+        String str = "";
+        try {
+            str = (new ObjectMapper()).writerWithDefaultPrettyPrinter().writeValueAsString(root);
+        } catch (JsonProcessingException e) {
+            log.error("Exception: ", e);
+        }
+        return str;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("json", root)
+                .toString();
+    }
+}
+
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ProgramCounter.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ProgramCounter.java
new file mode 100644
index 0000000..6af50e0
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ProgramCounter.java
@@ -0,0 +1,114 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import java.util.Objects;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * An interface representing workflow program counter.
+ */
+public final class ProgramCounter {
+
+    public static final ProgramCounter INIT_PC = ProgramCounter.valueOf(Worklet.Common.INIT.name(), 0);
+
+    /**
+     * index of the worklet.
+     */
+    private int workletIndex;
+
+    /**
+     * Type of worklet.
+     */
+    private String workletType;
+
+    /**
+     * Index of worklet.
+     * @return index of worklet
+     */
+    public int workletIndex() {
+        return this.workletIndex;
+    }
+
+    /**
+     * Type of worklet.
+     * @return type of worklet
+     */
+    public String workletType() {
+        return this.workletType;
+    }
+
+    /**
+     * Constructor of workflow Program Counter.
+     * @param workletType type of worklet
+     * @param workletIndex index of worklet
+     */
+    private ProgramCounter(String workletType, int workletIndex) {
+        this.workletType = workletType;
+        this.workletIndex = workletIndex;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(this.toString());
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == this) {
+            return true;
+        }
+        if (!(obj instanceof ProgramCounter)) {
+            return false;
+        }
+        return Objects.equals(this.workletType(), ((ProgramCounter) obj).workletType())
+                && Objects.equals(this.workletIndex(), ((ProgramCounter) obj).workletIndex());
+    }
+
+    @Override
+    public String toString() {
+        return String.format("(%d)%s", workletIndex, workletType);
+    }
+
+    /**
+     * Builder of workflow Program Counter.
+     * @param workletType type of worklet
+     * @param workletIndex index of worklet
+     * @return program counter
+     */
+    public static ProgramCounter valueOf(String workletType, int workletIndex) {
+        return new ProgramCounter(workletType, workletIndex);
+    }
+
+    /**
+     * Builder of workflow Program Counter.
+     * @param strProgramCounter string format for program counter
+     * @return program counter
+     */
+    public static ProgramCounter valueOf(String strProgramCounter) {
+
+        Matcher m = Pattern.compile("\\((\\d+)\\)(.+)").matcher(strProgramCounter);
+
+        if (!m.matches()) {
+            throw new IllegalArgumentException("Malformed program counter string");
+        }
+
+        return new ProgramCounter(m.group(2), Integer.parseInt(m.group(1)));
+    }
+
+}
+
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/RpcDescription.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/RpcDescription.java
new file mode 100644
index 0000000..5b067b4
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/RpcDescription.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.fasterxml.jackson.databind.JsonNode;
+
+/**
+ * Interface for workflow RPC description.
+ */
+public interface RpcDescription {
+
+    /**
+     * Workflow RPC operation pointer.
+     */
+    String RPC_OP_PTR = "/op";
+
+    /**
+     * Workflow RPC parameters pointer.
+     */
+    String RPC_PARAMS_PTR = "/params";
+
+    /**
+     * Workflow RPC invocation ID pointer.
+     */
+    String RPC_ID_PTR = "/id";
+
+    /**
+     * Returns workflow RPC operation.
+     * @return workflow RPC operation
+     */
+    String op();
+
+    /**
+     * Returns workflow RPC parameters.
+     * @return workflow RPC parameters
+     */
+    JsonNode params();
+
+    /**
+     * Returns workflow RPC invocation ID.
+     * @return workflow RPC invocation ID
+     */
+    String id();
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/SystemWorkflowContext.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/SystemWorkflowContext.java
new file mode 100644
index 0000000..4cc15bd
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/SystemWorkflowContext.java
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * WorkflowContext for system workflow.
+ */
+public class SystemWorkflowContext extends DefaultWorkflowContext {
+
+    /**
+     * Timestamp when this system workflow context was created.
+     */
+    private final long timestamp;
+
+    /**
+     * Distributor string for designating which onos node executes this workflow context with work partition.
+     */
+    private String distributor;
+
+    /**
+     * The constructor of SystemWorkflowContext.
+     * @param builder builder of SystemWorkflowContext
+     */
+    public SystemWorkflowContext(Builder builder) {
+        super(builder);
+        timestamp = System.currentTimeMillis();
+        //initial distributor(It can be changed)
+        distributor = name();
+    }
+
+    @Override
+    public String distributor() {
+        return distributor;
+    }
+
+    /**
+     * Sets distributor string of this workflow context.
+     * @param distributor distributor string
+     */
+    public void setDistributor(String distributor) {
+        this.distributor = distributor;
+    }
+
+    @Override
+    public String name() {
+        return workflowId().toString()
+                + ":" + timestamp
+                + "@" + workplaceName();
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("name", name())
+                .add("triggernext", triggerNext())
+                .add("data", data())
+                .add("current", current())
+                .add("state", state())
+                .add("cause", cause())
+                .toString();
+    }
+
+    /**
+     * Gets systemBuilder instance.
+     * @return systemBuilder instance
+     */
+    public static final Builder systemBuilder() {
+        return new Builder();
+    }
+
+    /**
+     * Builder for system workflow context.
+     */
+    public static class Builder extends DefaultWorkflowContext.Builder {
+
+        /**
+         * Builds system workflow context.
+         * @return instance of default workflow context.
+         */
+        public SystemWorkflowContext build() {
+            return new SystemWorkflowContext(this);
+        }
+    }
+
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/TimeoutTask.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/TimeoutTask.java
new file mode 100644
index 0000000..180d9eb
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/TimeoutTask.java
@@ -0,0 +1,72 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.google.common.base.MoreObjects;
+
+import static org.onosproject.workflow.api.CheckCondition.check;
+
+
+public final class TimeoutTask extends HandlerTask {
+
+    private TimeoutTask(Builder builder) {
+        super(builder);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("context", context())
+                .add("programCounter", programCounter())
+                .toString();
+    }
+
+    /**
+     * Gets a instance of builder.
+     * @return instance of builder
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Builder of TimeoutTask.
+     */
+    public static class Builder extends HandlerTask.Builder {
+        @Override
+        public Builder context(WorkflowContext context) {
+            super.context(context);
+            return this;
+        }
+
+        @Override
+        public Builder programCounter(ProgramCounter programCounter) {
+            super.programCounter(programCounter);
+            return this;
+        }
+
+        /**
+         * Builds TimeoutTask.
+         * @return instance of TimeoutTask
+         * @throws WorkflowException workflow exception
+         */
+        public TimeoutTask build() throws WorkflowException {
+            check(context != null, "context is invalid");
+            check(programCounter != null, "programCounter is invalid");
+            return new TimeoutTask(this);
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/TimerChain.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/TimerChain.java
new file mode 100644
index 0000000..afa2ac6
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/TimerChain.java
@@ -0,0 +1,248 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import java.util.Date;
+import java.util.Objects;
+import java.util.PriorityQueue;
+import java.util.Timer;
+import java.util.TimerTask;
+
+/**
+ * Class for time chain timer.
+ */
+public class TimerChain {
+
+    private PriorityQueue<TimerChainTask> taskQueue = new PriorityQueue<>();
+
+    private Timer impendingTimer;
+    private TimerChainTask impendingTask;
+
+    /**
+     * Constructor of timer chain.
+     */
+    public TimerChain() {
+
+    }
+
+    /**
+     * Schedules timer event.
+     * @param afterMs millisecond which time event happens.
+     * @param runnable runnable to be executed after 'afterMs'
+     */
+    public void schedule(long afterMs, Runnable runnable) {
+        schedule(new Date((new Date()).getTime() + afterMs), runnable);
+    }
+
+    /**
+     * Schedules timer event.
+     * @param date date which timer event happens.
+     * @param runnable runnable to be executed on 'date'
+     */
+    public void schedule(Date date, Runnable runnable) {
+        schedule(new TimerChainTask(this, date, runnable));
+    }
+
+    /**
+     * Schedule timer chain task.
+     * @param task task to be scheduled.
+     */
+    private void schedule(TimerChainTask task) {
+        synchronized (this) {
+            if (taskQueue.isEmpty()) {
+                scheduleImpending(task);
+                return;
+            }
+
+            if (task.date().getTime() < head().date().getTime()) {
+                impendingTimer.cancel();
+                impendingTask.cancel();
+                TimerChainTask prevImpendingTask = pop().copy();
+                taskQueue.offer(prevImpendingTask);
+
+                scheduleImpending(task);
+            } else {
+                taskQueue.offer(task);
+            }
+        }
+    }
+
+    /**
+     * Schedule impending timer task.
+     * @param task impending timer chain task
+     * @return timer chain task
+     */
+    private TimerChainTask scheduleImpending(TimerChainTask task) {
+        taskQueue.offer(task);
+        Timer timer = new Timer();
+        this.setImpendingTask(task);
+        this.setImpendingTimer(timer);
+        timer.schedule(task, task.date());
+        return task;
+    }
+
+    /**
+     * Gets impending timer.
+     * @return impending timer
+     */
+    public Timer implendingTimer() {
+        return impendingTimer;
+    }
+
+    /**
+     * Sets impending timer.
+     * @param impendingTimer impending timer
+     */
+    public void setImpendingTimer(Timer impendingTimer) {
+        this.impendingTimer = impendingTimer;
+    }
+
+    /**
+     * Gets impending timer task.
+     * @return impending timer task
+     */
+    public TimerTask impendingTask() {
+        return impendingTask;
+    }
+
+    /**
+     * Sets impending timer task.
+     * @param impendingTask impending timer task
+     */
+    public void setImpendingTask(TimerChainTask impendingTask) {
+        this.impendingTask = impendingTask;
+    }
+
+    /**
+     * Gets head of timer chain task queue.
+     * @return timer chain task
+     */
+    public TimerChainTask head() {
+        if (!taskQueue.isEmpty()) {
+            return taskQueue.peek();
+        } else {
+            return null;
+        }
+    }
+
+    /**
+     * Pops head of timer chain task queue.
+     * @return timer chain task
+     */
+    public TimerChainTask pop() {
+        if (!taskQueue.isEmpty()) {
+            return taskQueue.poll();
+        } else {
+            return null;
+        }
+    }
+
+    /**
+     * Class for timer chain task.
+     */
+    public static class TimerChainTask extends TimerTask implements Comparable<TimerChainTask> {
+
+        private final TimerChain timerchain;
+        private final Date date;
+        private final Runnable runnable;
+
+        /**
+         * Constructor of timer chain task.
+         * @param timerchain timer chain
+         * @param date date to be scheduled
+         * @param runnable runnable to be executed by timer
+         */
+        public TimerChainTask(TimerChain timerchain, Date date, Runnable runnable) {
+            this.timerchain = timerchain;
+            this.date = date;
+            this.runnable = runnable;
+        }
+
+        /**
+         * Gets date.
+         * @return date of timer chain task
+         */
+        public Date date() {
+            return this.date;
+        }
+
+        /**
+         * Gets runnable.
+         * @return runnable of timer chain task
+         */
+        public Runnable runnable() {
+            return this.runnable;
+        }
+
+        @Override
+        public void run() {
+
+            TimerChainTask nextTask;
+            synchronized (timerchain) {
+                if (timerchain.impendingTask() != this) {
+                    runnable().run();
+                    return;
+                }
+
+                timerchain.implendingTimer().cancel();
+                timerchain.pop();
+
+                nextTask = timerchain.head();
+
+                if (nextTask != null) {
+                    Timer nextTimer = new Timer();
+                    this.timerchain.setImpendingTask(nextTask);
+                    this.timerchain.setImpendingTimer(nextTimer);
+                    nextTimer.schedule(nextTask, nextTask.date());
+                }
+            }
+
+            runnable().run();
+
+        }
+
+        @Override
+        public int compareTo(TimerChainTask target) {
+            return date().compareTo(target.date());
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) {
+                return true;
+            }
+            if (!(o instanceof TimerChainTask)) {
+                return false;
+            }
+            TimerChainTask that = (TimerChainTask) o;
+
+            return this.date().equals(that.date());
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(date);
+        }
+
+        /**
+         * Copies timer chain task.
+         * @return timer chain task
+         */
+        public TimerChainTask copy() {
+            return new TimerChainTask(timerchain, date, runnable);
+        }
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkExecutor.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkExecutor.java
new file mode 100644
index 0000000..e834e81
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkExecutor.java
@@ -0,0 +1,29 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+/**
+ * Functional interface for delivering method reference of worklet completion event generator.
+ */
+@FunctionalInterface
+public interface WorkExecutor {
+
+    /**
+     * Applies this method reference.
+     * @throws WorkflowException workflow exception
+     */
+    void apply() throws WorkflowException;
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/Workflow.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/Workflow.java
new file mode 100644
index 0000000..848a706
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/Workflow.java
@@ -0,0 +1,94 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import java.net.URI;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * An interface representing workflow.
+ */
+public interface Workflow {
+
+    /**
+     * Id of workflow.
+     * @return id
+     */
+    URI id();
+
+    /**
+     * Returns init worklet.
+     * @param context workflow context
+     * @return init worklet
+     * @throws WorkflowException workflow exception
+     */
+    Worklet init(WorkflowContext context) throws WorkflowException;
+
+    /**
+     * Returns next program counter.
+     * @param context workflow context
+     * @return next program counter
+     * @throws WorkflowException workflow exception
+     */
+    ProgramCounter next(WorkflowContext context) throws WorkflowException;
+
+    /**
+     * Gets increased program coounter.
+     * @param pc program counter
+     * @return increased program counter
+     * @throws WorkflowException workflow exception
+     */
+    ProgramCounter increased(ProgramCounter pc) throws WorkflowException;
+
+    /**
+     * Returns instance of worklet.
+     * @param workletType class name of worklet
+     * @return instance of worklet
+     * @throws WorkflowException workflow exception
+     */
+    Worklet getWorkletInstance(String workletType) throws WorkflowException;
+
+    /**
+     * Builds workflow context.
+     * @param workplace workplace of system workflow
+     * @param data data model of system workflow context
+     * @return workflow context
+     * @throws WorkflowException workflow exception
+     */
+    WorkflowContext buildContext(Workplace workplace, DataModelTree data) throws WorkflowException;
+
+    /**
+     * Builds system workflow context.
+     * @param workplace workplace of system workflow
+     * @param data data model of system workflow context
+     * @return system workflow context
+     * @throws WorkflowException workflow exception
+     */
+    WorkflowContext buildSystemContext(Workplace workplace, DataModelTree data) throws WorkflowException;
+
+    /**
+     * Returns workflow attributes.
+     * @return attributes
+     */
+    Set<WorkflowAttribute> attributes();
+
+    /**
+     * Returns worklet type list.
+     * @return worklet type
+     */
+    List<String> getWorkletTypeList();
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowAttribute.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowAttribute.java
new file mode 100644
index 0000000..18ed701
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowAttribute.java
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+/**
+ * Attributes of workflow.
+ */
+public enum WorkflowAttribute {
+
+    /**
+     * Removes workflow context after completion of workflow.
+     */
+    REMOVE_AFTER_COMPLETE,
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowBatchDelegate.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowBatchDelegate.java
new file mode 100644
index 0000000..d54a92a
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowBatchDelegate.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.google.common.annotations.Beta;
+
+import java.util.Collection;
+
+/**
+ * Facade for receiving notifications from the workflow batch service.
+ */
+@Beta
+public interface WorkflowBatchDelegate {
+
+    /**
+     * Submits the specified batch of workflow operations for processing.
+     *
+     * @param operations batch of operations
+     */
+    void execute(Collection<WorkflowData> operations);
+
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowContext.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowContext.java
new file mode 100644
index 0000000..836524d
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowContext.java
@@ -0,0 +1,190 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import org.onosproject.event.Event;
+
+import java.net.URI;
+import java.util.Set;
+
+/**
+ * An abstract class representing WorkflowContext.
+ */
+public abstract class WorkflowContext extends WorkflowData {
+
+    /**
+     * Constructor of workflow context.
+     * @param data data model tree
+     */
+    public WorkflowContext(DataModelTree data) {
+        super(data);
+    }
+
+    /**
+     * Returns workflow id of this workflow context.
+     * @return workflow id
+     */
+    public abstract URI workflowId();
+
+    /**
+     * Returns workplace name.
+     * @return workplace name
+     */
+    public abstract String workplaceName();
+
+    /**
+     * Returns the current state of workflow context.
+     * @return current state of workflow context
+     */
+    public abstract WorkflowState state();
+
+    /**
+     * Sets the current state of workflow context.
+     * @param state current state of workflow context
+     */
+    public abstract void setState(WorkflowState state);
+
+    /**
+     * Sets the current program counter of workflow context.
+     * @param pc current program counter
+     */
+    public abstract void setCurrent(ProgramCounter pc);
+
+    /**
+     * Returns the current program counter of workflow.
+     * @return the current program counter of workflow
+     */
+    public abstract ProgramCounter current();
+
+    /**
+     * Returns the cause string of exception state.
+     * @return cause string
+     */
+    public abstract String cause();
+
+    /**
+     * Sets the cause string of exception state.
+     * @param cause cause string
+     */
+    public abstract void setCause(String cause);
+
+    /**
+     * Indicates the worklet process become completed.
+     * By calling this, workflow triggers the next worklet selection
+     */
+    public abstract void completed();
+
+    /**
+     * Waits an event which have 'eventHint' after executing executor.
+     * If the event happens, Worklet.isCompleted will be called.
+     * If the event does not happen for timeoutMs, Worklet.timeout will be called.
+     * @param eventType the class of event to wait
+     * @param eventHint the event of the event to wait
+     * @param eventGenerator a method reference to be executed after executing executor
+     * @param timeoutMs timeout millisecond
+     */
+    public abstract void waitCompletion(Class<? extends Event> eventType, String eventHint,
+                                        WorkExecutor eventGenerator, long timeoutMs);
+
+
+    /**
+     * Waits an event which has any one of eventHint from Set 'eventHintSet' after executing executor.
+     * If the event happens, Worklet.isCompleted will be called.
+     * If the event does not happen for timeoutMs, Worklet.timeout will be called.
+     * @param eventType the class of event to wait
+     * @param eventHintSet the Set of eventHints of the event to wait
+     * @param eventGenerator a method reference to be executed after executing executor
+     * @param timeoutMs timeout millisecond
+     */
+    public abstract void waitAnyCompletion(Class<? extends Event> eventType, Set<String> eventHintSet,
+                                           WorkExecutor eventGenerator, long timeoutMs);
+
+
+    /**
+     * Waits timeout milliseconds. After timeoutMs Worklet.timeout will be called.
+     * @param timeoutMs timeout millisecond
+     */
+    public abstract void waitFor(long timeoutMs);
+
+    /**
+     * Returns the class of a completion event to wait.
+     * @return the class of a completion event
+     */
+    public abstract Class<? extends Event> completionEventType();
+
+    /**
+     * Returns the set of event hint string to wait.
+     * @return the event hint string set
+     */
+    public abstract Set<String> completionEventHints();
+
+    /**
+     * Returns method reference for generating completion event.
+     * @return a method reference
+     */
+    public abstract WorkExecutor completionEventGenerator();
+
+    /**
+     * Returns completion event timeout.
+     * @return completion event timeout
+     */
+    public abstract long completionEventTimeout();
+
+    /**
+     * Sets workflow service.
+     * @param workflowExecutionService workflow service
+     */
+    public abstract void setWorkflowExecutionService(WorkflowExecutionService workflowExecutionService);
+
+    /**
+     * Gets workflow service.
+     * @return workflow service
+     */
+    public abstract WorkflowExecutionService workflowService();
+
+    /**
+     * Sets workflow store.
+     * @param workflowStore workflow store.
+     */
+    public abstract void setWorkflowStore(WorkflowStore workflowStore);
+
+    /**
+     * Gets worklow store.
+     * @return workflow store
+     */
+    public abstract WorkflowStore workflowStore();
+
+    /**
+     * Sets workplace store.
+     * @param workplaceStore work place store.
+     */
+    public abstract void setWorkplaceStore(WorkplaceStore workplaceStore);
+
+    /**
+     * Gets workplace store.
+     * @return workplace store
+     */
+    public abstract WorkplaceStore workplaceStore();
+
+    /**
+     * Get service.
+     * @param serviceClass service class
+     * @param <T> service class type
+     * @return service reference
+     * @throws WorkflowException workflow exception
+     */
+    public abstract <T> T getService(Class<T> serviceClass) throws WorkflowException;
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowData.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowData.java
new file mode 100644
index 0000000..6a8590c
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowData.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+
+/**
+ * An abstract class representing workflow data.
+ */
+public abstract class WorkflowData {
+
+    private DataModelTree data;
+    private boolean triggerNext = true; // default is true
+
+    /**
+     * Constructor of workflow data.
+     * @param data data model tree
+     */
+    public WorkflowData(DataModelTree data) {
+        this.data = data;
+    }
+
+    /**
+     * Returns name.
+     * @return name
+     */
+    public abstract String name();
+
+    /**
+     * Returns work-partition distributor.
+     * @return work-partition distributor
+     */
+    public abstract String distributor();
+
+    /**
+     * Returns context model tree.
+     * @return context model tree
+     */
+    public DataModelTree data() {
+        return data;
+    }
+
+    /**
+     * Returns whether to trigger next worklet selection.
+     * @return whether to trigger next worklet selection
+     */
+    public boolean triggerNext() {
+        return triggerNext;
+    }
+
+    /**
+     * Sets whether to handle update event.
+     * @param triggerNext whether to handle update event
+     */
+    public void setTriggerNext(boolean triggerNext) {
+        this.triggerNext = triggerNext;
+    }
+
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDataEvent.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDataEvent.java
new file mode 100644
index 0000000..4833251
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDataEvent.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import org.onosproject.event.AbstractEvent;
+
+/**
+ * Workflow data event class.
+ */
+public class WorkflowDataEvent extends AbstractEvent<WorkflowDataEvent.Type, WorkflowData> {
+
+    /**
+     * Workflow data event types.
+     */
+    public enum Type {
+
+        /**
+         * Insertion of workflow data.
+         */
+        INSERT,
+
+        /**
+         * Updation of workflow data.
+         */
+        UPDATE,
+
+        /**
+         * Removal of workflow data.
+         */
+        REMOVE
+    }
+
+    /**
+     * Constructor for workflow data event.
+     * @param type workflow data event type
+     * @param data workflow data
+     */
+    public WorkflowDataEvent(Type type, WorkflowData data) {
+        super(type, data);
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDataListener.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDataListener.java
new file mode 100644
index 0000000..b777e74
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDataListener.java
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import org.onosproject.event.EventListener;
+
+/**
+ * Interface for workflow data listener.
+ */
+public interface WorkflowDataListener extends EventListener<WorkflowDataEvent> {
+
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDataModelException.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDataModelException.java
new file mode 100644
index 0000000..7d17529
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDataModelException.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.workflow.api;
+
+
+import com.fasterxml.jackson.databind.JsonNode;
+
+import java.net.URI;
+import java.util.List;
+
+/**
+ * Workflow DataModel exception class.
+ */
+public class WorkflowDataModelException extends WorkflowException {
+
+    private URI workflowId;
+    private JsonNode parameterJson;
+    private List<String> errorMsgs;
+
+    /**
+     * Default Constructor for Workflow DataModel Exception.
+     *
+     * @param msg exception message
+     */
+    public WorkflowDataModelException(String msg) {
+
+        super(msg);
+    }
+
+    /**
+     * Constructor for Workflow DataModel Exception.
+     *
+     * @param workflowId id of workflow
+     * @param parameterJson paramter json data model
+     * @param errorMsgs error message for json data model
+     */
+    public WorkflowDataModelException(URI workflowId, JsonNode parameterJson, List<String> errorMsgs) {
+        super("Invalid workflow data model: " +
+                " workflow: " + workflowId.toString() +
+                ", parameter json: " + parameterJson.toString() +
+                ", errors: " + errorMsgs);
+        this.workflowId = workflowId;
+        this.parameterJson = parameterJson;
+        this.errorMsgs = errorMsgs;
+    }
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDescription.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDescription.java
new file mode 100644
index 0000000..ca483f0
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowDescription.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import java.net.URI;
+
+
+/**
+ * interface for workflow description.
+ */
+public interface WorkflowDescription {
+
+    /**
+     * Workflow workplace field name.
+     */
+    String WF_WORKPLACE = "workplace";
+
+    /**
+     * Workflow ID field name.
+     */
+    String WF_ID = "id";
+
+    /**
+     * Workflow data field name.
+     */
+    String WF_DATA = "data";
+
+    /**
+     * Gets workplace name.
+     * @return workplace name
+     */
+    String workplaceName();
+
+    /**
+     * Gets workflow ID.
+     * @return workflow ID
+     */
+    URI id();
+
+    /**
+     * Gets workflow context name.
+     * @return workflow context name
+     */
+    String workflowContextName();
+
+    /**
+     * Gets workflow data model.
+     * @return workflow data model
+     */
+    JsonNode data();
+
+    /**
+     * Gets json of workflow description.
+     * @return json of workflow description
+     */
+    JsonNode toJson();
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowException.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowException.java
new file mode 100644
index 0000000..09506bd
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowException.java
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+/**
+ * Workflow exception class.
+ */
+public class WorkflowException extends Exception {
+
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * Constructor for workflow exception.
+     * @param msg exception message
+     */
+    public WorkflowException(String msg) {
+        super(msg);
+    }
+
+    /**
+     * Constructor for workflow exception.
+     * @param e throwable to deliver
+     */
+    public WorkflowException(Throwable e) {
+        super(e);
+    }
+
+    /**
+     * Constructor for workflow exception.
+     * @param msg exception message
+     * @param e throwable to deliver
+     */
+    public WorkflowException(String msg, Throwable e) {
+        super(msg, e);
+    }
+
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowExecutionService.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowExecutionService.java
new file mode 100644
index 0000000..c5e00a7
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowExecutionService.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import org.onosproject.event.Event;
+import org.onosproject.event.ListenerService;
+
+import java.util.Set;
+
+/**
+ * Interface for workflow execution service.
+ */
+public interface WorkflowExecutionService extends ListenerService<WorkflowDataEvent, WorkflowDataListener> {
+
+    /**
+     * Executes init worklet.
+     * @param context workflow context
+     */
+    void execInitWorklet(WorkflowContext context);
+
+    /**
+     * Evals workflow context.
+     * @param contextName the name of workflow context
+     */
+    void eval(String contextName);
+
+    /**
+     * Triggers workflow event map.
+     * @param event triggering event
+     * @param generator event hint generation method reference
+     */
+    void eventMapTrigger(Event event, EventHintSupplier generator);
+
+    /**
+     * Registers workflow event map.
+     * @param eventType event type (class name of event)
+     * @param eventHintSet Set of event hint value
+     * @param contextName workflow context name to be called by this event map
+     * @param programCounterString worklet type to be called by this event map
+     * @throws WorkflowException workflow exception
+     */
+    void registerEventMap(Class<? extends Event> eventType, Set<String> eventHintSet,
+                          String contextName, String programCounterString) throws WorkflowException;
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowService.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowService.java
new file mode 100644
index 0000000..b11e835
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowService.java
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+
+import com.fasterxml.jackson.databind.JsonNode;
+
+/**
+ * Interface for workflow service.
+ */
+public interface WorkflowService {
+
+    /**
+     * Creates workplace.
+     * @param wpDesc workplace description
+     * @throws WorkflowException workflow exception
+     */
+    void createWorkplace(WorkplaceDescription wpDesc) throws WorkflowException;
+
+    /**
+     * Removes workplace.
+     * @param wpDesc workplace description
+     * @throws WorkflowException workflow exception
+     */
+    void removeWorkplace(WorkplaceDescription wpDesc) throws WorkflowException;
+
+    /**
+     * Clears all workplaces.
+     * @throws WorkflowException workflow exception
+     */
+    void clearWorkplace() throws WorkflowException;
+
+    /**
+     * Invokes workflow.
+     * @param wfDesc workflow description
+     * @throws WorkflowException workflow exception
+     */
+    void invokeWorkflow(WorkflowDescription wfDesc) throws WorkflowException;
+
+    /**
+     * Invokes workflow.
+     * @param worklowDescJson workflow description json
+     * @throws WorkflowException workflow exception
+     */
+    void invokeWorkflow(JsonNode worklowDescJson) throws WorkflowException;
+
+    /**
+     * Terminates workflow.
+     * @param wfDesc workflow description
+     * @throws WorkflowException workflow exception
+     */
+    void terminateWorkflow(WorkflowDescription wfDesc) throws WorkflowException;
+}
\ No newline at end of file
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowState.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowState.java
new file mode 100644
index 0000000..0f92624
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowState.java
@@ -0,0 +1,38 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+/**
+ * State of workflow.
+ */
+public enum WorkflowState {
+
+    /**
+     * Workflow is idle state.
+     */
+    IDLE,
+
+    /**
+     * Workflow is running state.
+     */
+    RUNNING,
+
+    /**
+     * Workflow is exception state.
+     */
+    EXCEPTION
+
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowStore.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowStore.java
new file mode 100644
index 0000000..ac0de4d
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkflowStore.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import java.net.URI;
+import java.util.Collection;
+
+/**
+ * Store for managing workflow.
+ */
+public interface WorkflowStore {
+
+    /**
+     * Registers workflow.
+     * @param workflow registering workflow
+     */
+    void register(Workflow workflow);
+
+    /**
+     * Unregisters workflow.
+     * @param id id of workflow
+     */
+    void unregister(URI id);
+
+    /**
+     * Gets workflow.
+     * @param id id of workflow
+     * @return workflow
+     */
+    Workflow get(URI id);
+
+    /**
+     * Gets all workflow.
+     * @return collection of workflow
+     */
+    Collection<Workflow> getAll();
+
+    /**
+     * Registers local class loader.
+     * @param loader class loader
+     */
+    void registerLocal(ClassLoader loader);
+
+    /**
+     * Unregisters local class loader.
+     * @param loader class loader
+     */
+    void unregisterLocal(ClassLoader loader);
+
+    /**
+     * Gets class from registered class loaders.
+     * @param name name of class
+     * @return class
+     * @throws ClassNotFoundException class not found exception
+     */
+    Class getClass(String name) throws ClassNotFoundException;
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/Worklet.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/Worklet.java
new file mode 100644
index 0000000..c4b4fb2
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/Worklet.java
@@ -0,0 +1,161 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+
+import org.onosproject.event.Event;
+
+/**
+ * An interface representing worklet. A workflow is composed of worklets.
+ */
+public interface Worklet {
+
+    int MAX_WORKS = 10000;
+
+    /**
+     * Returns tag name of worklet. class name is usually used.
+     * @return tag name
+     */
+    String tag();
+
+    /**
+     * Processes tasks of the worklet under the workflow context.
+     * @param context workflow context
+     * @throws WorkflowException workflow exception
+     */
+    void process(WorkflowContext context) throws WorkflowException;
+
+    /**
+     * Checks whether is this worklet next worklet to be done under the workflow context.
+     * @param context workflow context
+     * @return true means this worklet is the next worklet to be processed
+     * @throws WorkflowException workflow exception
+     */
+    boolean isNext(WorkflowContext context) throws WorkflowException;
+
+    /**
+     * Checks whether is this worklet completed or not. 'isCompleted' checking is triggered by an event task.
+     * @param context workflow context
+     * @param event an event triggering this 'isCompleted' checking
+     * @return completed or not
+     * @throws WorkflowException workflow exception
+     */
+    boolean isCompleted(WorkflowContext context, Event event) throws WorkflowException;
+
+    /**
+     * Completion event timeout handler.
+     * @param context workflow context
+     * @throws WorkflowException workflow exception
+     */
+    void timeout(WorkflowContext context) throws WorkflowException;
+
+    /**
+     * Common worklet enum.
+     */
+    enum Common implements Worklet {
+
+        /**
+         * Init worklet.
+         */
+        INIT {
+            @Override
+            public String tag() {
+                return INIT.name();
+            }
+
+            @Override
+            public void process(WorkflowContext context) throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").process should not be called");
+            }
+
+            @Override
+            public boolean isNext(WorkflowContext context) throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").isNext should not be called");
+            }
+
+            @Override
+            public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").isCompleted should not be called");
+            }
+
+            @Override
+            public void timeout(WorkflowContext context) throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").timeout should not be called");
+            }
+        },
+
+        /**
+         * Completed worklet.
+         */
+        COMPLETED {
+            @Override
+            public String tag() {
+                return COMPLETED.name();
+            }
+
+            @Override
+            public void process(WorkflowContext context) throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").process should not be called");
+            }
+
+            @Override
+            public boolean isNext(WorkflowContext context) throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").isNext should not be called");
+            }
+
+            @Override
+            public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").isCompleted should not be called");
+            }
+
+            @Override
+            public void timeout(WorkflowContext context) throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").timeout should not be called");
+            }
+        },
+
+        /**
+         * Interrupted worklet.
+         */
+        INTERRUPTED {
+            @Override
+            public String tag() {
+                return INTERRUPTED.name();
+            }
+
+            @Override
+            public void process(WorkflowContext context) throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").process should not be called");
+            }
+
+            @Override
+            public boolean isNext(WorkflowContext context) throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").isNext should not be called");
+            }
+
+            @Override
+            public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").isCompleted should not be called");
+            }
+
+            @Override
+            public void timeout(WorkflowContext context) throws WorkflowException {
+                throw new WorkflowException("(" + tag() + ").timeout should not be called");
+            }
+        }
+    }
+}
+
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/Workplace.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/Workplace.java
new file mode 100644
index 0000000..a7439d6
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/Workplace.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import java.util.Collection;
+
+/**
+ * Abstract class for workplace. A common workflow data container for multiple work-flows.
+ */
+public abstract class Workplace extends WorkflowData {
+
+    public static final String SYSTEM_WORKPLACE = "system-workplace";
+
+    /**
+     * Constructor of workplace.
+     * @param data data model tree
+     */
+    public Workplace(DataModelTree data) {
+        super(data);
+    }
+
+    /**
+     * Gets workflow contexts of workplace.
+     * @return collection of workflow context
+     * @throws WorkflowException workflow exception
+     */
+    abstract Collection<WorkflowContext> getContexts() throws WorkflowException;
+
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkplaceDescription.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkplaceDescription.java
new file mode 100644
index 0000000..16515eb
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkplaceDescription.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import java.util.Optional;
+
+/**
+ * Interface for workplace description.
+ */
+public interface WorkplaceDescription {
+
+    /**
+     * Workplace name field name.
+     */
+    String WP_NAME = "name";
+
+    /**
+     * Workplace data field name.
+     */
+    String WP_DATA = "data";
+
+    /**
+     * Gets workplace name.
+     * @return workplace name
+     */
+    String name();
+
+    /**
+     * Gets optional workplace data model.
+     * @return workplace optData model
+     */
+    Optional<JsonNode> data();
+
+    /**
+     * Gets json of workflow description.
+     * @return json of workflow description
+     */
+    JsonNode toJson();
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkplaceStore.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkplaceStore.java
new file mode 100644
index 0000000..b73cd4f
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkplaceStore.java
@@ -0,0 +1,118 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import org.onosproject.store.Store;
+import org.onosproject.store.service.StorageException;
+
+import java.util.Collection;
+
+/**
+ * Interface for workplace store.
+ */
+public interface WorkplaceStore extends Store<WorkflowDataEvent, WorkplaceStoreDelegate> {
+
+    /**
+     * Registers workplace on workplace store.
+     * @param name workplace name to register
+     * @param workplace workplace
+     * @throws StorageException storage exception
+     */
+    void registerWorkplace(String name, Workplace workplace) throws StorageException;
+
+    /**
+     * Removes workplace from workplace store.
+     * @param name workplace name to remove
+     * @throws StorageException storage exception
+     */
+    void removeWorkplace(String name) throws StorageException;
+
+    /**
+     * Gets workplace on workplace store.
+     * @param name workplace name to get
+     * @return workplace
+     * @throws StorageException storage exception
+     */
+    Workplace getWorkplace(String name) throws StorageException;
+
+    /**
+     * Commits workplace on workplace store.
+     * @param name workplace name to commit
+     * @param workplace workplace to commit
+     * @param handleEvent whether or not to handle workplace(workflow data) event
+     * @throws StorageException storage exception
+     */
+    void commitWorkplace(String name, Workplace workplace, boolean handleEvent) throws StorageException;
+
+    /**
+     * Gets all workplaces from workplace store.
+     * @return collection of workplace
+     * @throws StorageException storage exception
+     */
+    Collection<Workplace> getWorkplaces() throws StorageException;
+
+    /**
+     * Registers workflow context on workplace store.
+     * @param name workflow context name to register
+     * @param context workflow context to register
+     * @throws StorageException storage exception
+     */
+    void registerContext(String name, WorkflowContext context) throws StorageException;
+
+    /**
+     * Removes workflow context from workplace store.
+     * @param name workflow context name
+     * @throws StorageException storage exception
+     */
+    void removeContext(String name) throws StorageException;
+
+    /**
+     * Gets workflow context with name.
+     * @param name workflow context name to get
+     * @return workflow context
+     * @throws StorageException storage exception
+     */
+    WorkflowContext getContext(String name) throws StorageException;
+
+    /**
+     * Commits workflow context on workplace store.
+     * @param name workflow context name to commit
+     * @param context workflow context to commit
+     * @param handleEvent whether or not to handle workflow context(workflow data) event
+     * @throws StorageException storage exception
+     */
+    void commitContext(String name, WorkflowContext context, boolean handleEvent) throws StorageException;
+
+    /**
+     * Gets all workflow context from workplace store.
+     * @return collection of workflow context
+     * @throws StorageException storage exception
+     */
+    Collection<WorkflowContext> getContexts() throws StorageException;
+
+    /**
+     * Gets workflow contexts belonging to a workplace.
+     * @param workplaceName workplace name
+     * @return collection of workflow contexts belonging to a workplace
+     */
+    Collection<WorkflowContext> getWorkplaceContexts(String workplaceName);
+
+    /**
+     * Removes all workflow contexts beloinging to a workplace.
+     * @param workplaceName workplace name
+     */
+    void removeWorkplaceContexts(String workplaceName);
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkplaceStoreDelegate.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkplaceStoreDelegate.java
new file mode 100644
index 0000000..9e7ba14
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/WorkplaceStoreDelegate.java
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.api;
+
+import org.onosproject.store.StoreDelegate;
+
+/**
+ * Workplace store delegate.
+ */
+public interface WorkplaceStoreDelegate extends StoreDelegate<WorkflowDataEvent> {
+}
diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/package-info.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/package-info.java
new file mode 100644
index 0000000..7e68f8f
--- /dev/null
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Package for workflow APIs.
+ */
+package org.onosproject.workflow.api;
\ No newline at end of file
diff --git a/apps/workflow/app/BUCK b/apps/workflow/app/BUCK
new file mode 100644
index 0000000..bc7e9af
--- /dev/null
+++ b/apps/workflow/app/BUCK
@@ -0,0 +1,17 @@
+COMPILE_DEPS = [
+    '//lib:CORE_DEPS',
+    '//lib:KRYO',
+    '//lib:JACKSON',
+    '//lib:jsch',
+    '//lib:org.apache.karaf.shell.console',
+    '//lib:jackson-core',
+    '//lib:jackson-annotations',
+    '//lib:jackson-databind',
+    '//cli:onos-cli',
+    '//core/store/serializers:onos-core-serializers',
+    '//apps/workflow/api:onos-apps-workflow-api',
+]
+
+osgi_jar(
+    deps = COMPILE_DEPS,
+)
diff --git a/apps/workflow/app/BUILD b/apps/workflow/app/BUILD
new file mode 100644
index 0000000..d5af5a2
--- /dev/null
+++ b/apps/workflow/app/BUILD
@@ -0,0 +1,10 @@
+COMPILE_DEPS = CORE_DEPS + KRYO + JACKSON + CLI + [
+    "//core/store/serializers:onos-core-serializers",
+    "//core/store/primitives:onos-core-primitives",
+    "//apps/workflow/api:onos-apps-workflow-api",
+]
+
+osgi_jar(
+    karaf_command_packages = ["org.onosproject.workflow.cli"],
+    deps = COMPILE_DEPS,
+)
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowCommand.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowCommand.java
new file mode 100644
index 0000000..b0f4168
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowCommand.java
@@ -0,0 +1,119 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import org.apache.karaf.shell.commands.Argument;
+import org.apache.karaf.shell.commands.Command;
+import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.workflow.api.DefaultWorkflowDescription;
+import org.onosproject.workflow.api.WorkflowContext;
+import org.onosproject.workflow.api.WorkflowExecutionService;
+import org.onosproject.workflow.api.WorkflowService;
+import org.onosproject.workflow.api.WorkflowException;
+import org.onosproject.workflow.api.WorkplaceStore;
+
+import java.util.Objects;
+
+@Command(scope = "onos", name = "workflow", description = "workflow cli")
+public class WorkFlowCommand extends AbstractShellCommand {
+
+    static final String INVOKE = "invoke";
+    static final String EVAL   = "eval";
+
+
+
+    @Argument(index = 0, name = "cmd",
+            description = "command(" + INVOKE + "|" + EVAL + "eval)",
+            required = true)
+    private String cmd = null;
+
+    @Argument(index = 1, name = "name",
+            description = "workflow context name(workflow@workplace)",
+            required = true)
+    private String name = null;
+
+    @Override
+    protected void execute() {
+        if (Objects.isNull(cmd)) {
+            error("invalid cmd parameter");
+            return;
+        }
+
+        if (Objects.isNull(name)) {
+            error("invalid workflow context name");
+            return;
+        }
+
+        String[] tokens = name.split("@");
+        if (tokens != null && tokens.length != 2) {
+            error("invalid workflow context name(workflow@workplace)");
+            return;
+        }
+
+        String workflowId = tokens[0];
+        String workplace = tokens[1];
+
+        switch (cmd) {
+            case INVOKE:
+                invoke(workflowId, workplace);
+                break;
+            case EVAL:
+                eval(name);
+                break;
+            default:
+                print("Unsupported cmd: " + cmd);
+        }
+    }
+
+    /**
+     * Invokes workflow.
+     * @param workflowId workflow id
+     * @param workplaceName workplace name
+     */
+    private void invoke(String workflowId, String workplaceName) {
+
+        WorkflowService service = get(WorkflowService.class);
+        try {
+            DefaultWorkflowDescription wfDesc = DefaultWorkflowDescription.builder()
+                    .workplaceName(workplaceName)
+                    .id(workflowId)
+                    .data(JsonNodeFactory.instance.objectNode())
+                    .build();
+
+            service.invokeWorkflow(wfDesc);
+        } catch (WorkflowException e) {
+            error("Exception: ", e);
+        }
+    }
+
+    /**
+     * Evaluates workflow context.
+     * @param workflowContextName workflow context name
+     */
+    private void eval(String workflowContextName) {
+        WorkplaceStore storService = get(WorkplaceStore.class);
+        WorkflowExecutionService execService = get(WorkflowExecutionService.class);
+
+        WorkflowContext context = storService.getContext(workflowContextName);
+        if (context == null) {
+            error("failed to find workflow context {}", workflowContextName);
+            return;
+        }
+        execService.eval(workflowContextName);
+    }
+
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowCompleter.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowCompleter.java
new file mode 100644
index 0000000..9460c03
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowCompleter.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import com.google.common.collect.ImmutableList;
+import org.onosproject.cli.AbstractChoicesCompleter;
+
+import java.util.List;
+
+import static org.onosproject.workflow.cli.WorkFlowCommand.EVAL;
+import static org.onosproject.workflow.cli.WorkFlowCommand.INVOKE;
+
+
+/**
+ * Workflow command completer.
+ */
+public class WorkFlowCompleter extends AbstractChoicesCompleter {
+    @Override
+    protected List<String> choices() {
+        return ImmutableList.of(INVOKE, EVAL);
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowCtxtNameCompleter.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowCtxtNameCompleter.java
new file mode 100644
index 0000000..a8bd53a
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowCtxtNameCompleter.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import org.onosproject.cli.AbstractChoicesCompleter;
+import org.onosproject.workflow.api.WorkplaceStore;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static org.onlab.osgi.DefaultServiceDirectory.getService;
+
+/**
+ * Workflow context name completer.
+ */
+public class WorkFlowCtxtNameCompleter extends AbstractChoicesCompleter {
+    @Override
+    protected List<String> choices() {
+        WorkplaceStore workplaceStore = getService(WorkplaceStore.class);
+        return workplaceStore.getContexts().stream()
+                .map(workplace -> workplace.name())
+                .collect(Collectors.toList());
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowEventMapCommand.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowEventMapCommand.java
new file mode 100644
index 0000000..8eb0749
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowEventMapCommand.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.karaf.shell.commands.Argument;
+import org.apache.karaf.shell.commands.Command;
+import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.workflow.api.ContextEventMapStore;
+import org.onosproject.workflow.api.WorkflowException;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+@Command(scope = "onos", name = "workflow-eventmap", description = "workflow event map cli")
+public class WorkFlowEventMapCommand extends AbstractShellCommand {
+
+    @Argument(index = 0, name = "cmd", description = "command(print)", required = true)
+    private String cmd = null;
+
+    @Override
+    protected void execute() {
+        if (Objects.isNull(cmd)) {
+            error("invalid cmd parameter");
+            return;
+        }
+
+        ContextEventMapStore store = get(ContextEventMapStore.class);
+        try {
+            switch (cmd) {
+                case "print":
+                    JsonNode tree = store.asJsonTree();
+                    ObjectMapper mapper = new ObjectMapper();
+                    try {
+                        print(mapper.writerWithDefaultPrettyPrinter().writeValueAsString(tree));
+                    } catch (JsonProcessingException e) {
+                        error("Exception: " + e.getMessage() + ", trace: " + Arrays.asList(e.getStackTrace()));
+                    }
+                    break;
+
+                default:
+                    print("Unsupported cmd: " + cmd);
+            }
+        } catch (WorkflowException e) {
+            error(e.getMessage() + ", trace: " + Arrays.asList(e.getStackTrace()));
+        }
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowIdCompleter.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowIdCompleter.java
new file mode 100644
index 0000000..0f56184
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowIdCompleter.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import org.onosproject.cli.AbstractChoicesCompleter;
+import org.onosproject.workflow.api.WorkflowStore;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static org.onlab.osgi.DefaultServiceDirectory.getService;
+
+/**
+ * Workflow ID completer.
+ */
+public class WorkFlowIdCompleter extends AbstractChoicesCompleter {
+    @Override
+    protected List<String> choices() {
+        WorkflowStore workflowStore = getService(WorkflowStore.class);
+        return workflowStore.getAll().stream()
+                .map(workflow -> workflow.id().toString())
+                .collect(Collectors.toList());
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowStoreCommand.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowStoreCommand.java
new file mode 100644
index 0000000..dcf38a6
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowStoreCommand.java
@@ -0,0 +1,77 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import org.apache.karaf.shell.commands.Argument;
+import org.apache.karaf.shell.commands.Command;
+import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.workflow.api.Workflow;
+import org.onosproject.workflow.api.WorkflowStore;
+
+import java.util.Objects;
+import java.net.URI;
+
+@Command(scope = "onos", name = "workflowstore", description = "workflow store cli")
+public class WorkFlowStoreCommand extends AbstractShellCommand {
+
+    static final String RM = "rm";
+
+    @Argument(index = 0, name = "cmd",
+            description = "command(" + RM + ")", required = false)
+    private String cmd = null;
+
+    @Argument(index = 1, name = "id",
+            description = "workflow id(URI)", required = false)
+    private String id = null;
+
+    @Override
+    protected void execute() {
+
+        if (Objects.isNull(cmd)) {
+            printAllWorkflow();
+            return;
+        }
+
+        if (Objects.isNull(id)) {
+            print("invalid id");
+            return;
+        }
+
+        switch (cmd) {
+            case RM:
+                rmWorkflow(id);
+                break;
+            default:
+                print("Unsupported cmd: " + cmd);
+        }
+    }
+
+    private void rmWorkflow(String id) {
+        WorkflowStore workflowStore = get(WorkflowStore.class);
+        workflowStore.unregister(URI.create(id));
+    }
+
+    private void printAllWorkflow() {
+        WorkflowStore workflowStore = get(WorkflowStore.class);
+        for (Workflow workflow : workflowStore.getAll()) {
+            print(getWorkflowString(workflow));
+        }
+    }
+
+    private String getWorkflowString(Workflow workflow) {
+        return workflow.toString();
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowStoreCompleter.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowStoreCompleter.java
new file mode 100644
index 0000000..c6b425f
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowStoreCompleter.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import com.google.common.collect.ImmutableList;
+import org.onosproject.cli.AbstractChoicesCompleter;
+
+import java.util.List;
+
+import static org.onosproject.workflow.cli.WorkFlowStoreCommand.RM;
+
+/**
+ * Workflow Store command completer.
+ */
+public class WorkFlowStoreCompleter extends AbstractChoicesCompleter {
+    @Override
+    protected List<String> choices() {
+        return ImmutableList.of(RM);
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowTestCommand.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowTestCommand.java
new file mode 100644
index 0000000..c882e07
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowTestCommand.java
@@ -0,0 +1,152 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.apache.karaf.shell.commands.Argument;
+import org.apache.karaf.shell.commands.Command;
+import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.workflow.api.DefaultWorkflowDescription;
+import org.onosproject.workflow.api.WorkflowException;
+import org.onosproject.workflow.api.WorkflowService;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+/**
+ * Workflow test command.
+ */
+@Command(scope = "onos", name = "workflow-test", description = "workflow test cli")
+public class WorkFlowTestCommand extends AbstractShellCommand {
+
+    static final String INVOKE_SAMPLE = "invoke-sample";
+    static final String EXCEPTION_SAMPLE = "exception-sample";
+
+    @Argument(index = 0, name = "test-name",
+            description = "Test name (" + INVOKE_SAMPLE + " | " + EXCEPTION_SAMPLE + ")",
+            required = true)
+    private String testName = null;
+
+    @Argument(index = 1, name = "arg1",
+            description = "number of test for (" + INVOKE_SAMPLE + " | " + EXCEPTION_SAMPLE + ")",
+            required = false)
+    private String arg1 = null;
+
+    @Override
+    protected void execute() {
+        if (Objects.isNull(testName)) {
+            error("invalid test-name parameter");
+            return;
+        }
+
+        switch (testName) {
+            case INVOKE_SAMPLE:
+                if (Objects.isNull(arg1)) {
+                    error("arg1 is required for test " + INVOKE_SAMPLE);
+                    return;
+                }
+
+                int num;
+                try {
+                    num = Integer.parseInt(arg1);
+                } catch (NumberFormatException e) {
+                    error("arg1 should be an integer value");
+                    return;
+                } catch (Exception e) {
+                    error(e.getMessage() + ", trace: " + Arrays.asList(e.getStackTrace()));
+                    return;
+                }
+
+                invokeSampleTest(num);
+                break;
+
+            case EXCEPTION_SAMPLE:
+                if (Objects.isNull(arg1)) {
+                    error("arg1 is required for test " + EXCEPTION_SAMPLE);
+                    return;
+                }
+                int count;
+                try {
+                    count = Integer.parseInt(arg1);
+                } catch (NumberFormatException e) {
+                    error("arg1 should be an integer value");
+                    return;
+                } catch (Exception e) {
+                    error(e.getMessage() + ", trace: " + Arrays.asList(e.getStackTrace()));
+                    return;
+                }
+
+                invokeExceptionTest(count);
+                break;
+
+            default:
+                print("Unsupported test-name: " + testName);
+        }
+    }
+
+    /**
+     * Workflow invoke test_name.
+     *
+     * @param num the arg1 of workflow to test_name
+     */
+    private void invokeSampleTest(int num) {
+        for (int i = 0; i <= num; i++) {
+            String wpName = "test_name-" + i;
+            invoke("sample.workflow-0", wpName);
+            invoke("sample.workflow-1", wpName);
+            invoke("sample.workflow-2", wpName);
+        }
+    }
+
+    /**
+     * Workflow datatype exception test.
+     *
+     * @param num the number of workflow to test
+     */
+    private void invokeExceptionTest(int num) {
+        for (int i = 0; i <= num; i++) {
+            String wpName = "test-" + i;
+            invoke("sample.workflow-3", wpName);
+        }
+    }
+
+
+    /**
+     * Invokes workflow.
+     *
+     * @param workflowId    workflow id
+     * @param workplaceName workplace name
+     */
+    private void invoke(String workflowId, String workplaceName) {
+
+        WorkflowService service = get(WorkflowService.class);
+
+        ObjectNode dataModel = JsonNodeFactory.instance.objectNode();
+        dataModel.put("count", 0);
+
+        try {
+            DefaultWorkflowDescription wfDesc = DefaultWorkflowDescription.builder()
+                    .workplaceName(workplaceName)
+                    .id(workflowId)
+                    .data(dataModel)
+                    .build();
+            service.invokeWorkflow(wfDesc);
+        } catch (WorkflowException e) {
+            error(e.getMessage() + "trace: " + Arrays.asList(e.getStackTrace()));
+        }
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowTestCompleter.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowTestCompleter.java
new file mode 100644
index 0000000..d1fb7f4
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkFlowTestCompleter.java
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import com.google.common.collect.ImmutableList;
+import org.onosproject.cli.AbstractChoicesCompleter;
+
+import java.util.List;
+
+import static org.onosproject.workflow.cli.WorkFlowTestCommand.EXCEPTION_SAMPLE;
+import static org.onosproject.workflow.cli.WorkFlowTestCommand.INVOKE_SAMPLE;
+
+/**
+ * Workflow test command completer.
+ */
+public class WorkFlowTestCompleter  extends AbstractChoicesCompleter {
+    @Override
+    protected List<String> choices() {
+        return ImmutableList.of(INVOKE_SAMPLE, EXCEPTION_SAMPLE);
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkplaceNameCompleter.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkplaceNameCompleter.java
new file mode 100644
index 0000000..5dd2f23
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkplaceNameCompleter.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import org.onosproject.cli.AbstractChoicesCompleter;
+import org.onosproject.workflow.api.WorkplaceStore;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static org.onlab.osgi.DefaultServiceDirectory.getService;
+
+/**
+ * Workplace name completer.
+ */
+public class WorkplaceNameCompleter extends AbstractChoicesCompleter {
+    @Override
+    protected List<String> choices() {
+        WorkplaceStore workplaceStore = getService(WorkplaceStore.class);
+        return workplaceStore.getWorkplaces().stream()
+                .map(workplace -> workplace.name())
+                .collect(Collectors.toList());
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkplaceStoreCommand.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkplaceStoreCommand.java
new file mode 100644
index 0000000..f8c2310
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkplaceStoreCommand.java
@@ -0,0 +1,208 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import org.apache.karaf.shell.commands.Argument;
+import org.apache.karaf.shell.commands.Command;
+import org.apache.karaf.shell.commands.Option;
+import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.workflow.api.WorkflowContext;
+import org.onosproject.workflow.api.WorkflowException;
+import org.onosproject.workflow.api.WorkflowService;
+import org.onosproject.workflow.api.Workplace;
+import org.onosproject.workflow.api.DefaultWorkplaceDescription;
+import org.onosproject.workflow.api.WorkplaceStore;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+@Command(scope = "onos", name = "workplace",
+        description = "workplace cli")
+public class WorkplaceStoreCommand extends AbstractShellCommand {
+
+    static final String ADD   = "add";
+    static final String RM    = "rm";
+    static final String CLEAR = "clear";
+    static final String PRINT = "print";
+
+    @Argument(index = 0, name = "cmd",
+            description = "command(" + ADD + "/" + RM + "/" + CLEAR + "/" + PRINT + ")",
+            required = false)
+    private String cmd = null;
+
+    @Argument(index = 1, name = "name",
+            description = "workplace name",
+            required = false)
+    private String name = null;
+
+    @Option(name = "-f", aliases = "--filter", description = "including filter",
+            required = false, multiValued = false)
+    private String inFilter = null;
+
+    @Option(name = "-e", aliases = "--excludefilter", description = "excluding filter",
+            required = false, multiValued = false)
+    private String exFilter = null;
+
+    @Override
+    protected void execute() {
+
+        if (Objects.isNull(cmd)) {
+            printAllWorkplace();
+            return;
+        }
+
+        switch (cmd) {
+            case ADD:
+                if (Objects.isNull(name)) {
+                    error("invalid name");
+                    return;
+                }
+                addEmptyWorkplace(name);
+                return;
+
+            case RM:
+                if (Objects.isNull(name)) {
+                    print("invalid name");
+                    return;
+                }
+                rmWorkplace(name);
+                break;
+
+            case CLEAR:
+                clearWorkplace();
+                break;
+
+            case PRINT:
+                if (Objects.isNull(name)) {
+                    print("invalid name");
+                    return;
+                }
+                printWorkplace(name);
+                break;
+
+            default:
+                print("Unsupported cmd: " + cmd);
+        }
+    }
+
+    /**
+     * Adds empty workplace.
+     * @param name workplace name
+     */
+    private void addEmptyWorkplace(String name) {
+        WorkflowService service = get(WorkflowService.class);
+        try {
+            DefaultWorkplaceDescription wpDesc = DefaultWorkplaceDescription.builder()
+                    .name(name)
+                    .build();
+            service.createWorkplace(wpDesc);
+        } catch (WorkflowException e) {
+            error(e.getMessage() + ", trace: " + Arrays.asList(e.getStackTrace()));
+        }
+    }
+
+    /**
+     * Clears all workplaces.
+     */
+    private void clearWorkplace() {
+        WorkflowService service = get(WorkflowService.class);
+        try {
+            service.clearWorkplace();
+        } catch (WorkflowException e) {
+            error(e.getMessage() + ", trace: " + Arrays.asList(e.getStackTrace()));
+        }
+    }
+
+    /**
+     * Removes workplace.
+     * @param name workplace name to remove
+     */
+    private void rmWorkplace(String name) {
+        WorkflowService service = get(WorkflowService.class);
+        try {
+            DefaultWorkplaceDescription wpDesc = DefaultWorkplaceDescription.builder()
+                    .name(name)
+                    .build();
+            service.removeWorkplace(wpDesc);
+        } catch (WorkflowException e) {
+            error(e.getMessage() + ", trace: " + Arrays.asList(e.getStackTrace()));
+        }
+    }
+
+    /**
+     * Prints workplace.
+     * @param name workplace name
+     */
+    private void printWorkplace(String name) {
+        WorkplaceStore workplaceStore = get(WorkplaceStore.class);
+        Workplace workplace = workplaceStore.getWorkplace(name);
+        if (Objects.isNull(workplace)) {
+            print("Not existing workplace " + name);
+            return;
+        }
+        print(getWorkplaceString(workplace));
+    }
+
+    /**
+     * Prints all workplaces.
+     */
+    private void printAllWorkplace() {
+        WorkplaceStore workplaceStore = get(WorkplaceStore.class);
+        for (Workplace workplace : workplaceStore.getWorkplaces()) {
+            print(getWorkplaceString(workplace));
+            printWorkplaceContexts(workplaceStore, workplace.name());
+        }
+    }
+
+    /**
+     * Prints contexts of workplace.
+     * @param workplaceStore workplace store service
+     * @param workplaceName workplace name
+     */
+    private void printWorkplaceContexts(WorkplaceStore workplaceStore, String workplaceName) {
+        for (WorkflowContext context : workplaceStore.getWorkplaceContexts(workplaceName)) {
+            String str = context.toString();
+            if (Objects.nonNull(inFilter)) {
+                if (str.indexOf(inFilter) != -1) {
+                    if (Objects.nonNull(exFilter)) {
+                        if (str.indexOf(exFilter) == -1) {
+                            print(" - " + context);
+                        }
+                    } else {
+                        print(" - " + context);
+                    }
+                }
+            } else {
+                if (Objects.nonNull(exFilter)) {
+                    if (str.indexOf(exFilter) == -1) {
+                        print(" - " + context);
+                    }
+                } else {
+                    print(" - " + context);
+                }
+            }
+        }
+    }
+
+    /**
+     * Gets workplace string.
+     * @param workplace workplace
+     * @return workplace string
+     */
+    private String getWorkplaceString(Workplace workplace) {
+        return workplace.toString();
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkplaceStoreCompleter.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkplaceStoreCompleter.java
new file mode 100644
index 0000000..6654340
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/WorkplaceStoreCompleter.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.cli;
+
+import com.google.common.collect.ImmutableList;
+import org.onosproject.cli.AbstractChoicesCompleter;
+
+import java.util.List;
+
+import static org.onosproject.workflow.cli.WorkplaceStoreCommand.ADD;
+import static org.onosproject.workflow.cli.WorkplaceStoreCommand.CLEAR;
+import static org.onosproject.workflow.cli.WorkplaceStoreCommand.PRINT;
+import static org.onosproject.workflow.cli.WorkplaceStoreCommand.RM;
+
+/**
+ * Workplace store command completer.
+ */
+public class WorkplaceStoreCompleter extends AbstractChoicesCompleter {
+    @Override
+    protected List<String> choices() {
+        return ImmutableList.of(ADD, RM, CLEAR, PRINT);
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/package-info.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/package-info.java
new file mode 100644
index 0000000..0383d04
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/cli/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Workflow cli package.
+ */
+package org.onosproject.workflow.cli;
\ No newline at end of file
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/DistributedContextEventMapTreeStore.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/DistributedContextEventMapTreeStore.java
new file mode 100644
index 0000000..9554cd8
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/DistributedContextEventMapTreeStore.java
@@ -0,0 +1,247 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl;
+
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onosproject.store.service.EventuallyConsistentMap;
+import org.onosproject.store.service.WallClockTimestamp;
+import org.onlab.util.KryoNamespace;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.store.serializers.KryoNamespaces;
+import org.onosproject.store.service.AsyncDocumentTree;
+import org.onosproject.store.service.DocumentPath;
+import org.onosproject.store.service.IllegalDocumentModificationException;
+import org.onosproject.store.service.NoSuchDocumentPathException;
+import org.onosproject.store.service.Ordering;
+import org.onosproject.store.service.Serializer;
+import org.onosproject.store.service.StorageService;
+import org.onosproject.store.service.Versioned;
+import org.onosproject.workflow.api.ContextEventMapStore;
+import org.onosproject.workflow.api.WorkflowException;
+import org.slf4j.Logger;
+
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+@Component(immediate = true)
+public class DistributedContextEventMapTreeStore implements ContextEventMapStore {
+
+    protected static final Logger log = getLogger(DistributedContextEventMapTreeStore.class);
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private CoreService coreService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private StorageService storageService;
+
+    private ApplicationId appId;
+
+    private AsyncDocumentTree<String> eventMapTree;
+
+    private EventuallyConsistentMap<String, Set<String>> hintSetPerCxtMap;
+
+
+    @Activate
+    public void activate() {
+
+        appId = coreService.registerApplication("org.onosproject.contexteventmapstore");
+        log.info("appId=" + appId);
+
+        KryoNamespace eventMapNamespace = KryoNamespace.newBuilder()
+                .register(KryoNamespaces.API)
+                .build();
+
+        eventMapTree = storageService.<String>documentTreeBuilder()
+                .withSerializer(Serializer.using(eventMapNamespace))
+                .withName("context-event-map-store")
+                .withOrdering(Ordering.INSERTION)
+                .buildDocumentTree();
+
+        hintSetPerCxtMap = storageService.<String, Set<String>>eventuallyConsistentMapBuilder()
+                .withName("workflow-event-hint-per-cxt")
+                .withSerializer(eventMapNamespace)
+                .withTimestampProvider((k, v) -> new WallClockTimestamp())
+                .build();
+
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        eventMapTree.destroy();
+        hintSetPerCxtMap.destroy();
+        log.info("Stopped");
+    }
+
+    @Override
+    public void registerEventMap(String eventType, Set<String> eventHintSet,
+                                 String contextName, String programCounterString) throws WorkflowException {
+        for (String eventHint : eventHintSet) {
+            //Insert in eventCxtPerHintMap
+            DocumentPath dpathForCxt = DocumentPath.from(Lists.newArrayList(
+                    "root", eventType, eventHint, contextName));
+            String currentWorkletType = completeVersioned(eventMapTree.get(dpathForCxt));
+            if (currentWorkletType == null) {
+                complete(eventMapTree.createRecursive(dpathForCxt, programCounterString));
+            } else {
+                complete(eventMapTree.replace(dpathForCxt, programCounterString, currentWorkletType));
+            }
+            log.trace("RegisterEventMap for eventType:{}, eventSet:{}, contextName:{}, pc:{}",
+                     eventType, eventHintSet, contextName, programCounterString);
+
+        }
+        hintSetPerCxtMap.put(contextName, eventHintSet);
+        log.trace("RegisterEventMap in hintSetPerCxt for " +
+                         "eventType:{}, eventSet:{}, contextName:{}, pc:{}",
+                 eventType, eventHintSet, contextName, programCounterString);
+    }
+
+    @Override
+    public void unregisterEventMap(String eventType, String contextName)
+            throws WorkflowException {
+
+        Set<String> hints = hintSetPerCxtMap.get(contextName);
+        for (String eventHint : hints) {
+            //Remove from eventCxtPerHintMap
+            complete(eventMapTree.removeNode(DocumentPath.from(Lists.newArrayList(
+                    "root", eventType, eventHint, contextName))));
+            log.trace("UnregisterEventMap from eventCxtPerHintMap for eventType:{}, eventSet:{}, contextName:{}",
+                     eventType, eventHint, contextName);
+        }
+        hintSetPerCxtMap.remove(contextName);
+    }
+
+
+    @Override
+    public Map<String, String> getEventMapByHint(String eventType, String eventHint) throws WorkflowException {
+        DocumentPath path = DocumentPath.from(
+                Lists.newArrayList("root", eventType, eventHint));
+        Map<String, Versioned<String>> contexts = complete(eventMapTree.getChildren(path));
+        Map<String, String> eventMap = Maps.newHashMap();
+        if (Objects.isNull(contexts)) {
+            return eventMap;
+        }
+
+        for (Map.Entry<String, Versioned<String>> entry : contexts.entrySet()) {
+            eventMap.put(entry.getKey(), entry.getValue().value());
+        }
+        log.trace("getEventMapByHint returns eventMap {} ", eventMap);
+        return eventMap;
+    }
+
+    @Override
+    public boolean isEventMapPresent(String contextName) {
+        Map<String, String> eventMap = Maps.newHashMap();
+        Set<String> eventHintSet = hintSetPerCxtMap.get(contextName);
+        if (Objects.nonNull(eventHintSet)) {
+            log.trace("EventMap present for Context:{}", contextName);
+            return true;
+        } else {
+            log.trace("EventMap Doesnt exist for Context:{}", contextName);
+            return false;
+        }
+    }
+
+
+    @Override
+    public Map<String, Versioned<String>> getChildren(String path) throws WorkflowException {
+        DocumentPath dpath = DocumentPath.from(path);
+        Map<String, Versioned<String>> entries = complete(eventMapTree.getChildren(dpath));
+        return entries;
+    }
+
+    @Override
+    public DocumentPath getDocumentPath(String path) throws WorkflowException {
+        DocumentPath dpath = DocumentPath.from(path);
+        return dpath;
+    }
+
+    @Override
+    public ObjectNode asJsonTree() throws WorkflowException {
+
+        DocumentPath rootPath = DocumentPath.from(Lists.newArrayList("root"));
+        Map<String, Versioned<String>> eventmap = complete(eventMapTree.getChildren(rootPath));
+
+        ObjectNode rootNode = JsonNodeFactory.instance.objectNode();
+
+        for (Map.Entry<String, Versioned<String>> eventTypeEntry : eventmap.entrySet()) {
+
+            String eventType = eventTypeEntry.getKey();
+
+            ObjectNode eventTypeNode = JsonNodeFactory.instance.objectNode();
+            rootNode.put(eventType, eventTypeNode);
+
+            DocumentPath eventTypePath = DocumentPath.from(Lists.newArrayList("root", eventType));
+            Map<String, Versioned<String>> hintmap = complete(eventMapTree.getChildren(eventTypePath));
+
+            for (Map.Entry<String, Versioned<String>> hintEntry : hintmap.entrySet()) {
+
+                String hint = hintEntry.getKey();
+
+                ObjectNode hintNode = JsonNodeFactory.instance.objectNode();
+                eventTypeNode.put(hint, hintNode);
+
+                DocumentPath hintPath = DocumentPath.from(Lists.newArrayList("root", eventType, hint));
+                Map<String, Versioned<String>> contextmap = complete(eventMapTree.getChildren(hintPath));
+
+                for (Map.Entry<String, Versioned<String>> ctxtEntry : contextmap.entrySet()) {
+                    hintNode.put(ctxtEntry.getKey(), ctxtEntry.getValue().value());
+                }
+            }
+        }
+
+        return rootNode;
+    }
+
+    private <T> T complete(CompletableFuture<T> future) throws WorkflowException {
+        try {
+            return future.get();
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            throw new WorkflowException(e.getCause().getMessage());
+        } catch (ExecutionException e) {
+            if (e.getCause() instanceof IllegalDocumentModificationException) {
+                throw new WorkflowException("Node or parent does not exist or is root or is not a Leaf Node",
+                        e.getCause());
+            } else if (e.getCause() instanceof NoSuchDocumentPathException) {
+                return null;
+            } else {
+                throw new WorkflowException("Datastore operation failed", e.getCause());
+            }
+        }
+    }
+
+    private <T> T completeVersioned(CompletableFuture<Versioned<T>> future) throws WorkflowException {
+        return Optional.ofNullable(complete(future))
+                .map(Versioned::value)
+                .orElse(null);
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/DistributedWorkplaceStore.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/DistributedWorkplaceStore.java
new file mode 100644
index 0000000..1361758
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/DistributedWorkplaceStore.java
@@ -0,0 +1,394 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.BaseJsonNode;
+import com.fasterxml.jackson.databind.node.BigIntegerNode;
+import com.fasterxml.jackson.databind.node.BinaryNode;
+import com.fasterxml.jackson.databind.node.BooleanNode;
+import com.fasterxml.jackson.databind.node.ContainerNode;
+import com.fasterxml.jackson.databind.node.DecimalNode;
+import com.fasterxml.jackson.databind.node.DoubleNode;
+import com.fasterxml.jackson.databind.node.FloatNode;
+import com.fasterxml.jackson.databind.node.IntNode;
+import com.fasterxml.jackson.databind.node.JsonNodeCreator;
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.JsonNodeType;
+import com.fasterxml.jackson.databind.node.LongNode;
+import com.fasterxml.jackson.databind.node.MissingNode;
+import com.fasterxml.jackson.databind.node.NullNode;
+import com.fasterxml.jackson.databind.node.NumericNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.node.POJONode;
+import com.fasterxml.jackson.databind.node.ShortNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+import com.fasterxml.jackson.databind.node.ValueNode;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Maps;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onlab.util.KryoNamespace;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.workflow.api.DataModelTree;
+import org.onosproject.workflow.api.DefaultWorkplace;
+import org.onosproject.workflow.api.DefaultWorkflowContext;
+import org.onosproject.workflow.api.JsonDataModelTree;
+import org.onosproject.workflow.api.ProgramCounter;
+import org.onosproject.workflow.api.SystemWorkflowContext;
+import org.onosproject.workflow.api.WorkflowContext;
+import org.onosproject.workflow.api.WorkflowData;
+import org.onosproject.workflow.api.WorkflowState;
+import org.onosproject.workflow.api.Workplace;
+import org.onosproject.workflow.api.WorkflowDataEvent;
+import org.onosproject.workflow.api.WorkplaceStore;
+import org.onosproject.workflow.api.WorkplaceStoreDelegate;
+import org.onosproject.store.AbstractStore;
+import org.onosproject.store.serializers.KryoNamespaces;
+import org.onosproject.store.service.ConsistentMap;
+import org.onosproject.store.service.MapEvent;
+import org.onosproject.store.service.MapEventListener;
+import org.onosproject.store.service.Serializer;
+import org.onosproject.store.service.StorageException;
+import org.onosproject.store.service.StorageService;
+import org.onosproject.store.service.Versioned;
+import org.slf4j.Logger;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+@Component(immediate = true)
+public class DistributedWorkplaceStore
+    extends AbstractStore<WorkflowDataEvent, WorkplaceStoreDelegate> implements WorkplaceStore {
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected CoreService coreService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected StorageService storageService;
+
+    private ApplicationId appId;
+    private final Logger log = getLogger(getClass());
+
+    private final WorkplaceMapListener workplaceMapEventListener = new WorkplaceMapListener();
+    private ConsistentMap<String, WorkflowData> workplaceMap;
+    private Map<String, Workplace> localWorkplaceMap = Maps.newConcurrentMap();
+
+    private final WorkflowContextMapListener contextMapEventListener = new WorkflowContextMapListener();
+    private ConsistentMap<String, WorkflowData> contextMap;
+    private Map<String, WorkflowContext> localContextMap = Maps.newConcurrentMap();
+
+    private Map<String, Map<String, WorkflowContext>> localWorkplaceMemberMap = Maps.newConcurrentMap();
+
+    @Activate
+    public void activate() {
+
+        appId = coreService.registerApplication("org.onosproject.workplacestore");
+        log.info("appId=" + appId);
+
+        KryoNamespace workplaceNamespace = KryoNamespace.newBuilder()
+                .register(KryoNamespaces.API)
+                .register(WorkflowData.class)
+                .register(Workplace.class)
+                .register(DefaultWorkplace.class)
+                .register(WorkflowContext.class)
+                .register(DefaultWorkflowContext.class)
+                .register(SystemWorkflowContext.class)
+                .register(WorkflowState.class)
+                .register(ProgramCounter.class)
+                .register(DataModelTree.class)
+                .register(JsonDataModelTree.class)
+                .register(List.class)
+                .register(ArrayList.class)
+                .register(JsonNode.class)
+                .register(ObjectNode.class)
+                .register(TextNode.class)
+                .register(LinkedHashMap.class)
+                .register(ArrayNode.class)
+                .register(BaseJsonNode.class)
+                .register(BigIntegerNode.class)
+                .register(BinaryNode.class)
+                .register(BooleanNode.class)
+                .register(ContainerNode.class)
+                .register(DecimalNode.class)
+                .register(DoubleNode.class)
+                .register(FloatNode.class)
+                .register(IntNode.class)
+                .register(JsonNodeType.class)
+                .register(LongNode.class)
+                .register(MissingNode.class)
+                .register(NullNode.class)
+                .register(NumericNode.class)
+                .register(POJONode.class)
+                .register(ShortNode.class)
+                .register(ValueNode.class)
+                .register(JsonNodeCreator.class)
+                .register(JsonNodeFactory.class)
+                .build();
+
+        localWorkplaceMap.clear();
+        workplaceMap = storageService.<String, WorkflowData>consistentMapBuilder()
+                .withSerializer(Serializer.using(workplaceNamespace))
+                .withName("workplace-map")
+                .withApplicationId(appId)
+                .build();
+        workplaceMap.addListener(workplaceMapEventListener);
+
+        localContextMap.clear();
+        contextMap = storageService.<String, WorkflowData>consistentMapBuilder()
+                .withSerializer(Serializer.using(workplaceNamespace))
+                .withName("workflow-context-map")
+                .withApplicationId(appId)
+                .build();
+        contextMap.addListener(contextMapEventListener);
+
+        workplaceMapEventListener.syncLocal();
+        contextMapEventListener.syncLocal();
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        workplaceMap.destroy();
+        localWorkplaceMap.clear();
+        contextMap.destroy();
+        localContextMap.clear();
+
+        log.info("Stopped");
+    }
+
+    @Override
+    public void registerWorkplace(String name, Workplace workplace) throws StorageException {
+        workplaceMap.put(name, workplace);
+    }
+
+    @Override
+    public void removeWorkplace(String name) throws StorageException {
+        removeWorkplaceContexts(name);
+        workplaceMap.remove(name);
+    }
+
+    @Override
+    public Workplace getWorkplace(String name) throws StorageException {
+        return localWorkplaceMap.get(name);
+    }
+
+    @Override
+    public Collection<Workplace> getWorkplaces() throws StorageException {
+        return ImmutableList.copyOf(localWorkplaceMap.values());
+    }
+
+    @Override
+    public void commitWorkplace(String name, Workplace workplace, boolean handleEvent) throws StorageException {
+        workplace.setTriggerNext(handleEvent);
+        if (workplaceMap.containsKey(name)) {
+            workplaceMap.replace(name, workplace);
+        } else {
+            registerWorkplace(name, workplace);
+        }
+    }
+
+    @Override
+    public void registerContext(String name, WorkflowContext context) throws StorageException {
+        contextMap.put(name, context);
+    }
+
+    @Override
+    public void removeContext(String name) throws StorageException {
+        contextMap.remove(name);
+    }
+
+    @Override
+    public WorkflowContext getContext(String name) throws StorageException {
+        return localContextMap.get(name);
+    }
+
+    @Override
+    public void commitContext(String name, WorkflowContext context, boolean handleEvent) throws StorageException {
+        context.setTriggerNext(handleEvent);
+        if (contextMap.containsKey(name)) {
+            contextMap.replace(name, context);
+        } else {
+            registerContext(name, context);
+        }
+    }
+
+    @Override
+    public Collection<WorkflowContext> getContexts() throws StorageException {
+        return ImmutableList.copyOf(localContextMap.values());
+    }
+
+    @Override
+    public Collection<WorkflowContext> getWorkplaceContexts(String workplaceName) {
+        Map<String, WorkflowContext> ctxMap = localWorkplaceMemberMap.get(workplaceName);
+        if (ctxMap == null) {
+            return Collections.emptyList();
+        }
+
+        return ImmutableList.copyOf(ctxMap.values());
+    }
+
+    @Override
+    public void removeWorkplaceContexts(String workplaceName) {
+        for (WorkflowContext ctx : getWorkplaceContexts(workplaceName)) {
+            removeContext(ctx.name());
+        }
+    }
+
+    private class WorkplaceMapListener implements MapEventListener<String, WorkflowData> {
+
+        @Override
+        public void event(MapEvent<String, WorkflowData> event) {
+
+            Workplace newWorkplace = (Workplace) Versioned.valueOrNull(event.newValue());
+            Workplace oldWorkplace = (Workplace) Versioned.valueOrNull(event.oldValue());
+
+            log.info("WorkplaceMap event: {}", event);
+            switch (event.type()) {
+                case INSERT:
+                    insert(newWorkplace);
+                    notifyDelegate(new WorkflowDataEvent(WorkflowDataEvent.Type.INSERT, newWorkplace));
+                    break;
+                case UPDATE:
+                    update(newWorkplace);
+                    notifyDelegate(new WorkflowDataEvent(WorkflowDataEvent.Type.UPDATE, newWorkplace));
+                    break;
+                case REMOVE:
+                    remove(oldWorkplace);
+                    notifyDelegate(new WorkflowDataEvent(WorkflowDataEvent.Type.REMOVE, oldWorkplace));
+                    break;
+                default:
+            }
+        }
+
+        private void insert(Workplace workplace) {
+            localWorkplaceMap.put(workplace.name(), workplace);
+        }
+
+        private void update(Workplace workplace) {
+            localWorkplaceMap.replace(workplace.name(), workplace);
+        }
+
+        private void remove(Workplace workplace) {
+            localWorkplaceMap.remove(workplace.name());
+        }
+
+        public void syncLocal() {
+            workplaceMap.values().stream().forEach(
+                    x -> insert((Workplace) (x.value()))
+            );
+        }
+    }
+
+    private class WorkflowContextMapListener implements MapEventListener<String, WorkflowData> {
+
+        @Override
+        public void event(MapEvent<String, WorkflowData> event) {
+
+            WorkflowContext newContext = (WorkflowContext) Versioned.valueOrNull(event.newValue());
+            WorkflowContext oldContext = (WorkflowContext) Versioned.valueOrNull(event.oldValue());
+
+            log.debug("WorkflowContext event: {}", event);
+            switch (event.type()) {
+                case INSERT:
+                    insert(newContext);
+                    notifyDelegate(new WorkflowDataEvent(WorkflowDataEvent.Type.INSERT, newContext));
+                    break;
+                case UPDATE:
+                    update(newContext);
+                    notifyDelegate(new WorkflowDataEvent(WorkflowDataEvent.Type.UPDATE, newContext));
+                    break;
+                case REMOVE:
+                    remove(oldContext);
+                    notifyDelegate(new WorkflowDataEvent(WorkflowDataEvent.Type.REMOVE, oldContext));
+                    break;
+                default:
+            }
+        }
+
+        /**
+         * Inserts workflow context on local hash map.
+         * @param context workflow context
+         */
+        private void insert(WorkflowContext context) {
+            String workplaceName = context.workplaceName();
+            Map<String, WorkflowContext> ctxMap = localWorkplaceMemberMap.get(workplaceName);
+            if (ctxMap == null) {
+                ctxMap = new HashMap<>();
+                localWorkplaceMemberMap.put(workplaceName, ctxMap);
+            }
+            ctxMap.put(context.name(), context);
+
+            localContextMap.put(context.name(), context);
+        }
+
+        /**
+         * Updates workflow context on local hash map.
+         * @param context workflow context
+         */
+        private void update(WorkflowContext context) {
+            String workplaceName = context.workplaceName();
+            Map<String, WorkflowContext> ctxMap = localWorkplaceMemberMap.get(workplaceName);
+            if (ctxMap == null) {
+                ctxMap = new HashMap<>();
+                localWorkplaceMemberMap.put(workplaceName, ctxMap);
+            }
+            ctxMap.put(context.name(), context);
+
+            localContextMap.put(context.name(), context);
+        }
+
+        /**
+         * Removes workflow context from local hash map.
+         * @param context workflow context
+         */
+        private void remove(WorkflowContext context) {
+            localContextMap.remove(context.name());
+
+            String workplaceName = context.workplaceName();
+            Map<String, WorkflowContext> ctxMap = localWorkplaceMemberMap.get(workplaceName);
+            if (ctxMap == null) {
+                log.error("remove-context: Failed to find workplace({}) in localWorkplaceMemberMap", workplaceName);
+                return;
+            }
+            ctxMap.remove(context.name());
+            if (ctxMap.size() == 0) {
+                localWorkplaceMemberMap.remove(workplaceName, ctxMap);
+            }
+        }
+
+        /**
+         * Synchronizes local hash map.
+         */
+        public void syncLocal() {
+            contextMap.values().stream().forEach(
+                    x -> insert((WorkflowContext) (x.value()))
+            );
+        }
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/ECWorkFlowStore.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/ECWorkFlowStore.java
new file mode 100644
index 0000000..8cd56ec
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/ECWorkFlowStore.java
@@ -0,0 +1,153 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onlab.util.KryoNamespace;
+import org.slf4j.Logger;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.workflow.api.AbstractWorkflow;
+import org.onosproject.workflow.api.ImmutableListWorkflow;
+import org.onosproject.workflow.api.Workflow;
+import org.onosproject.workflow.api.WorkflowAttribute;
+import org.onosproject.workflow.api.WorkflowStore;
+import org.onosproject.net.group.GroupEvent;
+import org.onosproject.net.group.GroupStoreDelegate;
+import org.onosproject.store.AbstractStore;
+import org.onosproject.store.serializers.KryoNamespaces;
+import org.onosproject.store.service.EventuallyConsistentMap;
+import org.onosproject.store.service.StorageService;
+import org.onosproject.store.service.WallClockTimestamp;
+
+import java.net.URI;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+import java.util.List;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+@Component(immediate = true)
+public class ECWorkFlowStore
+    extends AbstractStore<GroupEvent, GroupStoreDelegate> implements WorkflowStore {
+
+    private final Logger log = getLogger(getClass());
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected CoreService coreService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected StorageService storageService;
+
+    private ApplicationId appId;
+    private EventuallyConsistentMap<URI, Workflow> workflowStore;
+    private Set<ClassLoader> classloaders = Sets.newConcurrentHashSet();
+
+    @Activate
+    public void activate() {
+
+        appId = coreService.registerApplication("org.onosproject.nfconfig");
+        log.info("appId=" + appId);
+
+        KryoNamespace.Builder workflowSerializer = KryoNamespace.newBuilder()
+                .register(KryoNamespaces.API)
+                .register(URI.class)
+                .register(Workflow.class)
+                .register(AbstractWorkflow.class)
+                .register(ImmutableListWorkflow.class)
+                .register(List.class)
+                .register(ImmutableList.class)
+                .register(Class.class)
+                .register(WorkflowAttribute.class)
+                .register(Set.class)
+                .register(ImmutableSet.class)
+                .register(HashSet.class);
+
+        workflowStore = storageService.<URI, Workflow>eventuallyConsistentMapBuilder()
+                .withName("workflow-workplaceStore")
+                .withSerializer(workflowSerializer)
+                .withAntiEntropyPeriod(5, TimeUnit.SECONDS)
+                .withTimestampProvider((k, v) -> new WallClockTimestamp())
+                .withTombstonesDisabled()
+                .build();
+
+        classloaders.add(this.getClass().getClassLoader());
+
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        workflowStore.destroy();
+
+        log.info("Stopped");
+    }
+
+    @Override
+    public void register(Workflow workflow) {
+        workflowStore.put(workflow.id(), workflow);
+    }
+
+    @Override
+    public void unregister(URI id) {
+        workflowStore.remove(id);
+    }
+
+    @Override
+    public Workflow get(URI id) {
+        return workflowStore.get(id);
+    }
+
+    @Override
+    public Collection<Workflow> getAll() {
+        return workflowStore.values();
+    }
+
+    @Override
+    public void registerLocal(ClassLoader loader) {
+        classloaders.add(loader);
+    }
+
+    @Override
+    public void unregisterLocal(ClassLoader loader) {
+        classloaders.remove(loader);
+    }
+
+    @Override
+    public Class getClass(String name) throws ClassNotFoundException {
+        for (ClassLoader loader : classloaders) {
+            Class cl = null;
+            try {
+                cl = loader.loadClass(name);
+            } catch (ClassNotFoundException e) {
+                // do nothing
+            }
+            if (cl != null) {
+                return cl;
+            }
+        }
+        throw new ClassNotFoundException(name);
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/HandlerTaskAccumulator.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/HandlerTaskAccumulator.java
new file mode 100644
index 0000000..4651cd4
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/HandlerTaskAccumulator.java
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl;
+
+import com.google.common.collect.ArrayListMultimap;
+import com.google.common.collect.ListMultimap;
+import org.onlab.util.AbstractAccumulator;
+import org.onosproject.workflow.api.HandlerTask;
+import org.onosproject.workflow.api.HandlerTaskBatchDelegate;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Timer;
+
+/**
+ * An accumulator for building batches of event task operations. Only one batch should
+ * be in process per instance at a time.
+ */
+public class HandlerTaskAccumulator extends AbstractAccumulator<HandlerTask> {
+
+    private static final int DEFAULT_MAX_EVENTS = 5000;
+    private static final int DEFAULT_MAX_IDLE_MS = 10;
+    private static final int DEFAULT_MAX_BATCH_MS = 50;
+
+    private static final Timer TIMER = new Timer("onos-workflow-handlertask-batching");
+
+    private final HandlerTaskBatchDelegate delegate;
+
+    private volatile boolean ready;
+
+    /**
+     * Creates an event-task operation accumulator.
+     *
+     * @param delegate the event-task batch delegate
+     */
+    protected HandlerTaskAccumulator(HandlerTaskBatchDelegate delegate) {
+        super(TIMER, DEFAULT_MAX_EVENTS, DEFAULT_MAX_BATCH_MS, DEFAULT_MAX_IDLE_MS);
+        this.delegate = delegate;
+        // Assume that the delegate is ready for workletType at the start
+        ready = true; //TODO validate the assumption that delegate is ready
+    }
+
+    @Override
+    public void processItems(List<HandlerTask> items) {
+        ready = false;
+        delegate.execute(epoch(items));
+    }
+
+    /**
+     * Gets epoch.
+     * @param ops handler tasks
+     * @return collection of collection of handler task.
+     */
+    private Collection<Collection<HandlerTask>> epoch(List<HandlerTask> ops) {
+
+        ListMultimap<String, HandlerTask> tasks = ArrayListMultimap.create();
+
+        // align event-tasks with context
+        for (HandlerTask op : ops) {
+            tasks.put(op.context().name(), op);
+        }
+
+        return tasks.asMap().values();
+    }
+
+    @Override
+    public boolean isReady() {
+        return ready;
+    }
+
+    /**
+     * Making accumulator to be ready.
+     */
+    public void ready() {
+        ready = true;
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkFlowEngine.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkFlowEngine.java
new file mode 100644
index 0000000..8f1d109
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkFlowEngine.java
@@ -0,0 +1,843 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl;
+
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onosproject.cluster.ClusterService;
+import org.onosproject.cluster.LeadershipService;
+import org.onosproject.cluster.NodeId;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.store.service.StorageException;
+import org.onosproject.workflow.api.DefaultWorkplace;
+import org.onosproject.workflow.api.EventHintSupplier;
+import org.onosproject.workflow.api.EventTask;
+import org.onosproject.workflow.api.JsonDataModelInjector;
+import org.onosproject.workflow.api.JsonDataModelTree;
+import org.onosproject.workflow.api.ProgramCounter;
+import org.onosproject.workflow.api.SystemWorkflowContext;
+import org.onosproject.workflow.api.EventTimeoutTask;
+import org.onosproject.workflow.api.TimeoutTask;
+import org.onosproject.workflow.api.TimerChain;
+import org.onosproject.workflow.api.Worklet;
+import org.onosproject.workflow.api.Workflow;
+import org.onosproject.workflow.api.WorkflowContext;
+import org.onosproject.workflow.api.WorkflowData;
+import org.onosproject.workflow.api.ContextEventMapStore;
+import org.onosproject.workflow.api.WorkflowState;
+import org.onosproject.workflow.api.WorkflowStore;
+import org.onosproject.workflow.api.WorkflowBatchDelegate;
+import org.onosproject.workflow.api.WorkflowDataEvent;
+import org.onosproject.workflow.api.WorkflowDataListener;
+import org.onosproject.workflow.api.WorkflowException;
+import org.onosproject.workflow.api.HandlerTask;
+import org.onosproject.workflow.api.HandlerTaskBatchDelegate;
+import org.onosproject.workflow.api.Workplace;
+import org.onosproject.workflow.api.WorkplaceStore;
+import org.onosproject.workflow.api.WorkplaceStoreDelegate;
+import org.onosproject.workflow.api.WorkflowExecutionService;
+import org.onosproject.event.AbstractListenerManager;
+import org.onosproject.event.Event;
+import org.onosproject.net.intent.WorkPartitionService;
+import org.slf4j.Logger;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.stream.Collectors;
+
+import static java.util.concurrent.Executors.newFixedThreadPool;
+import static java.util.concurrent.Executors.newSingleThreadExecutor;
+import static java.util.concurrent.Executors.newSingleThreadScheduledExecutor;
+import static org.onlab.util.Tools.groupedThreads;
+import static org.onosproject.workflow.api.WorkflowAttribute.REMOVE_AFTER_COMPLETE;
+import static org.slf4j.LoggerFactory.getLogger;
+
+@Component(immediate = true)
+public class WorkFlowEngine extends AbstractListenerManager<WorkflowDataEvent, WorkflowDataListener>
+        implements WorkflowExecutionService {
+
+    protected static final Logger log = getLogger(WorkFlowEngine.class);
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected CoreService coreService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ClusterService clusterService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected LeadershipService leadershipService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkPartitionService partitionService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkplaceStore workplaceStore;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkflowStore workflowStore;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ContextEventMapStore eventMapStore;
+
+    private final WorkplaceStoreDelegate workplaceStoreDelegate = this::post;
+
+    private final WorkflowBatchDelegate workflowBatchDelegate = new InternalWorkflowBatchDelegate();
+    private final WorkflowAccumulator workflowAccumulator = new WorkflowAccumulator(workflowBatchDelegate);
+
+    private final HandlerTaskBatchDelegate eventtaskBatchDelegate = new InternalHandlerTaskBatchDelegate();
+    private final HandlerTaskAccumulator eventtaskAccumulator = new HandlerTaskAccumulator(eventtaskBatchDelegate);
+
+    private ExecutorService workflowBatchExecutor;
+    private ExecutorService workflowExecutor;
+
+    private ExecutorService handlerTaskBatchExecutor;
+    private ExecutorService handlerTaskExecutor;
+
+    private static final int DEFAULT_WORKFLOW_THREADS = 12;
+    private static final int DEFAULT_EVENTTASK_THREADS = 12;
+    private static final int MAX_REGISTER_EVENTMAP_WAITS = 10;
+
+    private ScheduledExecutorService eventMapTriggerExecutor;
+
+    private TimerChain timerChain = new TimerChain();
+
+    private JsonDataModelInjector dataModelInjector = new JsonDataModelInjector();
+
+    public static final String APPID = "org.onosproject.workflow";
+    private ApplicationId appId;
+    private NodeId localNodeId;
+
+    @Activate
+    public void activate() {
+        appId = coreService.registerApplication(APPID);
+        workplaceStore.setDelegate(workplaceStoreDelegate);
+        localNodeId = clusterService.getLocalNode().id();
+        leadershipService.runForLeadership(appId.name());
+
+        workflowBatchExecutor = newSingleThreadExecutor(
+                groupedThreads("onos/workflow", "workflow-batch", log));
+        workflowExecutor = newFixedThreadPool(DEFAULT_WORKFLOW_THREADS,
+                groupedThreads("onos/workflow-exec", "worker-%d", log));
+        handlerTaskBatchExecutor = newSingleThreadExecutor(
+                groupedThreads("onos/workflow", "handlertask-batch", log));
+        handlerTaskExecutor = newFixedThreadPool(DEFAULT_EVENTTASK_THREADS,
+                groupedThreads("onos/handlertask-exec", "worker-%d", log));
+        eventMapTriggerExecutor = newSingleThreadScheduledExecutor(
+                groupedThreads("onos/workflow-engine", "eventmap-trigger-executor"));
+
+        (new WorkplaceWorkflow(this, workflowStore)).registerWorkflows();
+        JsonDataModelTree data = new JsonDataModelTree(JsonNodeFactory.instance.objectNode());
+        workplaceStore.registerWorkplace(Workplace.SYSTEM_WORKPLACE,
+                new DefaultWorkplace(Workplace.SYSTEM_WORKPLACE, data));
+
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        leadershipService.withdraw(appId.name());
+        workplaceStore.unsetDelegate(workplaceStoreDelegate);
+        workflowBatchExecutor.shutdown();
+        workflowExecutor.shutdown();
+        handlerTaskBatchExecutor.shutdown();
+        handlerTaskExecutor.shutdown();
+        eventMapTriggerExecutor.shutdown();
+        log.info("Stopped");
+    }
+
+    @Override
+    public void execInitWorklet(WorkflowContext context) {
+
+        Workflow workflow = workflowStore.get(context.workflowId());
+        if (workflow == null) {
+            log.error("Invalid workflow {}", context.workflowId());
+            return;
+        }
+
+        initWorkletExecution(context);
+        try {
+            Worklet initWorklet = workflow.init(context);
+            if (initWorklet != null) {
+
+                log.info("{} worklet.process:{}", context.name(), initWorklet.tag());
+                log.trace("{} context: {}", context.name(), context);
+
+                dataModelInjector.inject(initWorklet, context);
+                initWorklet.process(context);
+                dataModelInjector.inhale(initWorklet, context);
+
+                log.info("{} worklet.process(done): {}", context.name(), initWorklet.tag());
+                log.trace("{} context: {}", context.name(), context);
+            }
+
+        } catch (WorkflowException e) {
+            log.error("Exception: ", e);
+            context.setCause(e.getMessage());
+            context.setState(WorkflowState.EXCEPTION);
+            workplaceStore.commitContext(context.name(), context, false);
+            return;
+        }
+        // trigger the execution of next worklet.
+        workplaceStore.registerContext(context.name(), context);
+    }
+
+    @Override
+    public void eval(String contextName) {
+
+        final WorkflowContext latestContext = workplaceStore.getContext(contextName);
+        if (latestContext == null) {
+            log.error("Invalid workflow context {}", contextName);
+            return;
+        }
+
+        initWorkletExecution(latestContext);
+
+        workplaceStore.commitContext(latestContext.name(), latestContext, true);
+    }
+
+    @Override
+    public void eventMapTrigger(Event event, EventHintSupplier supplier) {
+
+        if (event.subject() instanceof SystemWorkflowContext) {
+            return;
+        }
+
+        Map<String, String> eventMap;
+
+        String eventHint;
+        try {
+            eventHint = supplier.apply(event);
+        } catch (Throwable e) {
+            log.error("Exception: ", e);
+            return;
+        }
+        if (eventHint == null) {
+            // do nothing
+            log.error("Invalid eventHint, event: {}", event);
+            return;
+        }
+
+        try {
+            eventMap = eventMapStore.getEventMapByHint(event.getClass().getName(), eventHint);
+        } catch (WorkflowException e) {
+            log.error("Exception: ", e);
+            return;
+        }
+
+        if (Objects.isNull(eventMap) || eventMap.isEmpty()) {
+            // do nothing;
+            log.debug("Invalid eventMap, event: {}", event);
+            return;
+        }
+
+        for (Map.Entry<String, String> entry : eventMap.entrySet()) {
+            String contextName = entry.getKey();
+            String strProgramCounter = entry.getValue();
+            ProgramCounter pc;
+            try {
+                pc = ProgramCounter.valueOf(strProgramCounter);
+            } catch (IllegalArgumentException e) {
+                log.error("Exception: ", e);
+                return;
+            }
+
+            WorkflowContext context = workplaceStore.getContext(contextName);
+            if (Objects.isNull(context)) {
+                log.info("Invalid context: {}, event: {}", contextName, event);
+                continue;
+            }
+            EventTask eventtask = null;
+            try {
+                eventtask = EventTask.builder()
+                    .event(event)
+                    .eventHint(eventHint)
+                    .context(context)
+                    .programCounter(pc)
+                    .build();
+            } catch (WorkflowException e) {
+                log.error("Exception: ", e);
+            }
+
+            log.debug("eventtaskAccumulator.add: task: {}", eventtask);
+            if (!Objects.isNull(eventtask)) {
+                eventtaskAccumulator.add(eventtask);
+            }
+        }
+    }
+
+    @Override
+    public void registerEventMap(Class<? extends Event> eventType, Set<String> eventHintSet,
+                                 String contextName, String programCounterString) throws WorkflowException {
+        eventMapStore.registerEventMap(eventType.getName(), eventHintSet, contextName, programCounterString);
+        for (String eventHint : eventHintSet) {
+            for (int i = 0; i < MAX_REGISTER_EVENTMAP_WAITS; i++) {
+                Map<String, String> eventMap = eventMapStore.getEventMapByHint(eventType.getName(), eventHint);
+                if (eventMap != null && eventMap.containsKey(contextName)) {
+                    break;
+                }
+                try {
+                    log.info("sleep {}", i);
+                    Thread.sleep(10L * (i + 1));
+                } catch (InterruptedException e) {
+                    log.error("Exception: ", e);
+                    Thread.currentThread().interrupt();
+                }
+            }
+        }
+
+    }
+
+    @Override
+    protected void post(WorkflowDataEvent event) {
+
+        if (event.subject() == null || !isRelevant(event.subject())) {
+            log.debug("ignore event {}", event);
+            return;
+        }
+
+        // trigger next worklet selection
+        WorkflowData dataModelContainer = event.subject();
+        switch (event.type()) {
+            case INSERT:
+            case UPDATE:
+                if (dataModelContainer.triggerNext()) {
+                    log.debug("workflowAccumulator.add: {}", dataModelContainer);
+                    workflowAccumulator.add(dataModelContainer);
+                } else {
+                    log.debug("pass-workflowAccumulator.add: {}", dataModelContainer);
+                }
+                break;
+            case REMOVE:
+                break;
+            default:
+        }
+
+        // trigger EventTask for WorkflowDataEvent
+        eventMapTriggerExecutor.submit(
+                () -> eventMapTrigger(
+                        event,
+                        // event hint supplier
+                        (ev) -> {
+                            if (ev == null || ev.subject() == null) {
+                                return null;
+                            }
+
+                            if (ev.subject() instanceof WorkflowData) {
+                                return ((WorkflowData) ev.subject()).name();
+                            } else {
+                                return null;
+                            }
+                        }
+                )
+        );
+    }
+
+    /**
+     * Checks whether this workflow data job is relevant to this ONOS node.
+     * @param job workflow data
+     * @return checking result
+     */
+    private boolean isRelevant(WorkflowData job) {
+        // distributes event processing with work-partition
+        return partitionService.isMine(job.distributor(), this::stringHash);
+    }
+
+    /**
+     * Gets hash of the string.
+     * @param str string to get a hash
+     * @return hash value
+     */
+    public Long stringHash(String str) {
+        return UUID.nameUUIDFromBytes(str.getBytes()).getMostSignificantBits();
+    }
+
+    /**
+     * Class for handler task batch delegation.
+     */
+    private class InternalHandlerTaskBatchDelegate implements HandlerTaskBatchDelegate {
+        @Override
+        public void execute(Collection<Collection<HandlerTask>> operations) {
+            log.debug("Execute {} operation(s).", operations.size());
+
+            CompletableFuture.runAsync(() -> {
+                List<CompletableFuture<Collection<HandlerTask>>> futures = operations.stream()
+                        .map(
+                                x -> CompletableFuture.completedFuture(x)
+                                        .thenApplyAsync(WorkFlowEngine.this::processHandlerTask, handlerTaskExecutor)
+                                        .exceptionally(e -> null)
+                        )
+                        .collect(Collectors.toList());
+
+                // waiting the completion of futures
+                futures.parallelStream().forEach(x -> x.join());
+
+            }, handlerTaskBatchExecutor).exceptionally(e -> {
+                log.error("Error submitting batches:", e);
+                return null;
+            }).thenRun(eventtaskAccumulator::ready);
+        }
+    }
+
+    /**
+     * Initializes worklet execution.
+     * @param context workflow context
+     */
+    private void initWorkletExecution(WorkflowContext context) {
+        context.setState(WorkflowState.RUNNING);
+        context.setCause("");
+        context.setWorkflowExecutionService(this);
+        context.setWorkflowStore(workflowStore);
+        context.setWorkplaceStore(workplaceStore);
+        context.waitCompletion(null, null, null, 0L);
+        context.setTriggerNext(false);
+    }
+
+    /**
+     * Processes handler tasks.
+     * @param tasks handler tasks
+     * @return handler tasks processed
+     */
+    private Collection<HandlerTask> processHandlerTask(Collection<HandlerTask> tasks) {
+
+        for (HandlerTask task : tasks) {
+            if (task instanceof EventTimeoutTask) {
+                execEventTimeoutTask((EventTimeoutTask) task);
+            } else if (task instanceof TimeoutTask) {
+                execTimeoutTask((TimeoutTask) task);
+            } else if (task instanceof EventTask) {
+                execEventTask((EventTask) task);
+            } else {
+                log.error("Unsupported handler task {}", task);
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Executes event task.
+     * @param task event task
+     * @return event task
+     */
+    private EventTask execEventTask(EventTask task) {
+
+        if (!eventMapStore.isEventMapPresent(task.context().name())) {
+            log.trace("EventMap doesnt exist for taskcontext:{}", task.context().name());
+            return task;
+        }
+
+        log.debug("execEventTask- task: {}, hash: {}", task, stringHash(task.context().distributor()));
+
+        WorkflowContext context = (WorkflowContext) (task.context());
+        Workflow workflow = workflowStore.get(context.workflowId());
+        if (workflow == null) {
+            log.error("Invalid workflow {}", context.workflowId());
+            return task;
+        }
+
+        WorkflowContext latestContext = workplaceStore.getContext(context.name());
+        if (latestContext == null) {
+            log.error("Invalid workflow context {}", context.name());
+            return task;
+        }
+
+        try {
+            if (!Objects.equals(latestContext.current(), task.programCounter())) {
+                log.error("Current worklet({}) is not mismatched with task work({}). Ignored.",
+                        latestContext.current(), task.programCounter());
+                return task;
+            }
+
+            Worklet worklet = workflow.getWorkletInstance(task.programCounter().workletType());
+            if (Worklet.Common.COMPLETED.equals(worklet) || Worklet.Common.INIT.equals(worklet)) {
+                log.error("Current worklet is {}, Ignored", worklet);
+                return task;
+            }
+
+            initWorkletExecution(latestContext);
+
+            log.info("{} worklet.isCompleted:{}", latestContext.name(), worklet.tag());
+            log.trace("{} task:{}, context: {}", latestContext.name(), task, latestContext);
+
+            dataModelInjector.inject(worklet, latestContext);
+            boolean completed = worklet.isCompleted(latestContext, task.event());
+            dataModelInjector.inhale(worklet, latestContext);
+
+            if (completed) {
+
+                log.info("{} worklet.isCompleted(true):{}", latestContext.name(), worklet.tag());
+                log.trace("{} task:{}, context: {}", latestContext.name(), task, latestContext);
+
+                eventMapStore.unregisterEventMap(
+                        task.eventType(), latestContext.name());
+
+                //completed case
+                //increase program counter
+                ProgramCounter pc = latestContext.current();
+                latestContext.setCurrent(workflow.increased(pc));
+
+                workplaceStore.commitContext(latestContext.name(), latestContext, true);
+                return null;
+            } else {
+
+                log.info("{} worklet.isCompleted(false):{}", latestContext.name(), worklet.tag());
+                log.trace("{} task:{}, context: {}", latestContext.name(), task, latestContext);
+
+                workplaceStore.commitContext(latestContext.name(), latestContext, false);
+            }
+
+        } catch (WorkflowException e) {
+            log.error("Exception: ", e);
+            latestContext.setCause(e.getMessage());
+            latestContext.setState(WorkflowState.EXCEPTION);
+            workplaceStore.commitContext(latestContext.name(), latestContext, false);
+        } catch (StorageException e) {
+            log.error("Exception: ", e);
+            // StorageException does not commit context.
+        } catch (Exception e) {
+            log.error("Exception: ", e);
+            latestContext.setCause(e.getMessage());
+            latestContext.setState(WorkflowState.EXCEPTION);
+            workplaceStore.commitContext(latestContext.name(), latestContext, false);
+        }
+
+        return task;
+    }
+
+    /**
+     * Executes event timeout task.
+     * @param task event timeout task
+     * @return handler task
+     */
+    private HandlerTask execEventTimeoutTask(EventTimeoutTask task) {
+
+        if (!eventMapStore.isEventMapPresent(task.context().name())) {
+            log.trace("EventMap doesnt exist for taskcontext:{}", task.context().name());
+            return task;
+        }
+
+        log.debug("execEventTimeoutTask- task: {}, hash: {}", task, stringHash(task.context().distributor()));
+
+        WorkflowContext context = (WorkflowContext) (task.context());
+        Workflow workflow = workflowStore.get(context.workflowId());
+        if (workflow == null) {
+            log.error("execEventTimeoutTask: Invalid workflow {}", context.workflowId());
+            return task;
+        }
+
+        WorkflowContext latestContext = workplaceStore.getContext(context.name());
+        if (latestContext == null) {
+            log.error("execEventTimeoutTask: Invalid workflow context {}", context.name());
+            return task;
+        }
+
+        try {
+            if (!Objects.equals(latestContext.current(), task.programCounter())) {
+                log.error("execEventTimeoutTask: Current worklet({}) is not mismatched with task work({}). Ignored.",
+                        latestContext.current(), task.programCounter());
+                return task;
+            }
+
+            Worklet worklet = workflow.getWorkletInstance(task.programCounter().workletType());
+            if (worklet == Worklet.Common.COMPLETED || worklet == Worklet.Common.INIT) {
+                log.error("execEventTimeoutTask: Current worklet is {}, Ignored", worklet);
+                return task;
+            }
+
+            initWorkletExecution(latestContext);
+
+            eventMapStore.unregisterEventMap(task.eventType(), latestContext.name());
+
+            log.info("{} worklet.timeout(for event):{}", latestContext.name(), worklet.tag());
+            log.trace("{} task:{}, context: {}", latestContext.name(), task, latestContext);
+
+            dataModelInjector.inject(worklet, latestContext);
+            worklet.timeout(latestContext);
+            dataModelInjector.inhale(worklet, latestContext);
+
+            log.info("{} worklet.timeout(for event)(done):{}", latestContext.name(), worklet.tag());
+            log.trace("{} task:{}, context: {}", latestContext.name(), task, latestContext);
+
+
+            workplaceStore.commitContext(latestContext.name(), latestContext, latestContext.triggerNext());
+
+        } catch (WorkflowException e) {
+            log.error("Exception: ", e);
+            latestContext.setCause(e.getMessage());
+            latestContext.setState(WorkflowState.EXCEPTION);
+            workplaceStore.commitContext(latestContext.name(), latestContext, false);
+        } catch (StorageException e) {
+            log.error("Exception: ", e);
+            // StorageException does not commit context.
+        } catch (Exception e) {
+            log.error("Exception: ", e);
+            latestContext.setCause(e.getMessage());
+            latestContext.setState(WorkflowState.EXCEPTION);
+            workplaceStore.commitContext(latestContext.name(), latestContext, false);
+        }
+
+        return task;
+    }
+
+    /**
+     * Executes timeout task.
+     * @param task time out task
+     * @return handler task
+     */
+    private HandlerTask execTimeoutTask(TimeoutTask task) {
+
+        log.debug("execTimeoutTask- task: {}, hash: {}", task, stringHash(task.context().distributor()));
+
+        WorkflowContext context = (WorkflowContext) (task.context());
+        Workflow workflow = workflowStore.get(context.workflowId());
+        if (workflow == null) {
+            log.error("execTimeoutTask: Invalid workflow {}", context.workflowId());
+            return task;
+        }
+
+        WorkflowContext latestContext = workplaceStore.getContext(context.name());
+        if (latestContext == null) {
+            log.error("execTimeoutTask: Invalid workflow context {}", context.name());
+            return task;
+        }
+
+        try {
+            if (!Objects.equals(latestContext.current(), task.programCounter())) {
+                log.error("execTimeoutTask: Current worklet({}) is not mismatched with task work({}). Ignored.",
+                        latestContext.current(), task.programCounter());
+                return task;
+            }
+
+            Worklet worklet = workflow.getWorkletInstance(task.programCounter().workletType());
+            if (worklet == Worklet.Common.COMPLETED || worklet == Worklet.Common.INIT) {
+                log.error("execTimeoutTask: Current worklet is {}, Ignored", worklet);
+                return task;
+            }
+
+            initWorkletExecution(latestContext);
+
+            log.info("{} worklet.timeout:{}", latestContext.name(), worklet.tag());
+            log.trace("{} context: {}", latestContext.name(), latestContext);
+
+            dataModelInjector.inject(worklet, latestContext);
+            worklet.timeout(latestContext);
+            dataModelInjector.inhale(worklet, latestContext);
+
+            log.info("{} worklet.timeout(done):{}", latestContext.name(), worklet.tag());
+            log.trace("{} context: {}", latestContext.name(), latestContext);
+
+            workplaceStore.commitContext(latestContext.name(), latestContext, latestContext.triggerNext());
+
+        } catch (WorkflowException e) {
+            log.error("Exception: ", e);
+            latestContext.setCause(e.getMessage());
+            latestContext.setState(WorkflowState.EXCEPTION);
+            workplaceStore.commitContext(latestContext.name(), latestContext, false);
+        } catch (StorageException e) {
+            log.error("Exception: ", e);
+            // StorageException does not commit context.
+        } catch (Exception e) {
+            log.error("Exception: ", e);
+            latestContext.setCause(e.getMessage());
+            latestContext.setState(WorkflowState.EXCEPTION);
+            workplaceStore.commitContext(latestContext.name(), latestContext, false);
+        }
+
+        return task;
+    }
+
+    /**
+     * Class for delegation of workflow batch execution.
+     */
+    private class InternalWorkflowBatchDelegate implements WorkflowBatchDelegate {
+        @Override
+        public void execute(Collection<WorkflowData> operations) {
+            log.debug("Execute {} operation(s).", operations.size());
+
+            CompletableFuture.runAsync(() -> {
+                List<CompletableFuture<WorkflowData>> futures = operations.stream()
+                        .map(
+                                x -> CompletableFuture.completedFuture(x)
+                                .thenApplyAsync(WorkFlowEngine.this::execWorkflow, workflowExecutor)
+                                .exceptionally(e -> null)
+                        )
+                        .collect(Collectors.toList());
+
+                // waiting the completion of futures
+                futures.parallelStream().forEach(x -> x.join());
+
+            }, workflowBatchExecutor).exceptionally(e -> {
+                log.error("Error submitting batches:", e);
+                return null;
+            }).thenRun(workflowAccumulator::ready);
+        }
+    }
+
+    /**
+     * Executes workflow.
+     * @param dataModelContainer workflow data model container(workflow or workplace)
+     * @return
+     */
+    private WorkflowData execWorkflow(WorkflowData dataModelContainer) {
+        if (dataModelContainer instanceof WorkflowContext) {
+            return execWorkflowContext((WorkflowContext) dataModelContainer);
+        } else if (dataModelContainer instanceof Workplace) {
+            return execWorkplace((Workplace) dataModelContainer);
+        } else {
+            log.error("Invalid context {}", dataModelContainer);
+            return null;
+        }
+    }
+
+    /**
+     * Executes workflow context.
+     * @param context workflow context
+     * @return workflow context
+     */
+    private WorkflowContext execWorkflowContext(WorkflowContext context) {
+
+        Workflow workflow = workflowStore.get(context.workflowId());
+        if (workflow == null) {
+            log.error("Invalid workflow {}", context.workflowId());
+            return null;
+        }
+
+        final WorkflowContext latestContext = workplaceStore.getContext(context.name());
+        if (latestContext == null) {
+            log.error("Invalid workflow context {}", context.name());
+            return null;
+        }
+
+        initWorkletExecution(latestContext);
+
+        try {
+            final ProgramCounter pc = workflow.next(latestContext);
+            final Worklet worklet = workflow.getWorkletInstance(pc.workletType());
+
+            if (worklet == Worklet.Common.INIT) {
+                log.error("workflow.next gave INIT. It cannot be executed (context: {})", context.name());
+                return latestContext;
+            }
+
+            latestContext.setCurrent(pc);
+            if (worklet == Worklet.Common.COMPLETED) {
+
+                if (workflow.attributes().contains(REMOVE_AFTER_COMPLETE)) {
+                    workplaceStore.removeContext(latestContext.name());
+                    return null;
+                } else {
+                    latestContext.setState(WorkflowState.IDLE);
+                    workplaceStore.commitContext(latestContext.name(), latestContext, false);
+                    return latestContext;
+                }
+            }
+
+            log.info("{} worklet.process:{}", latestContext.name(), worklet.tag());
+            log.trace("{} context: {}", latestContext.name(), latestContext);
+
+            dataModelInjector.inject(worklet, latestContext);
+            worklet.process(latestContext);
+            dataModelInjector.inhale(worklet, latestContext);
+
+            log.info("{} worklet.process(done): {}", latestContext.name(), worklet.tag());
+            log.trace("{} context: {}", latestContext.name(), latestContext);
+
+
+            if (latestContext.completionEventType() != null) {
+                if (latestContext.completionEventGenerator() == null) {
+                    String msg = String.format("Invalid exepecting event(%s), generator(%s)",
+                            latestContext.completionEventType(),
+                            latestContext.completionEventGenerator());
+                    throw new WorkflowException(msg);
+                }
+
+                registerEventMap(latestContext.completionEventType(), latestContext.completionEventHints(),
+                        latestContext.name(), pc.toString());
+
+                latestContext.completionEventGenerator().apply();
+
+                if (latestContext.completionEventTimeout() != 0L) {
+                    final EventTimeoutTask eventTimeoutTask = EventTimeoutTask.builder()
+                            .context(latestContext)
+                            .programCounter(pc)
+                            .eventType(latestContext.completionEventType().getName())
+                            .eventHintSet(latestContext.completionEventHints())
+                            .build();
+                    timerChain.schedule(latestContext.completionEventTimeout(),
+                            () -> {
+                                eventtaskAccumulator.add(eventTimeoutTask);
+                            });
+                }
+            } else {
+                if (latestContext.completionEventTimeout() != 0L) {
+                    final TimeoutTask timeoutTask = TimeoutTask.builder()
+                            .context(latestContext)
+                            .programCounter(pc)
+                            .build();
+
+                    timerChain.schedule(latestContext.completionEventTimeout(),
+                            () -> {
+                                eventtaskAccumulator.add(timeoutTask);
+                            });
+                } else {
+                    //completed case
+                    // increase program counter
+                    latestContext.setCurrent(workflow.increased(pc));
+                }
+            }
+
+            workplaceStore.commitContext(latestContext.name(), latestContext, latestContext.triggerNext());
+
+        } catch (WorkflowException e) {
+            log.error("Exception: ", e);
+            latestContext.setCause(e.getMessage());
+            latestContext.setState(WorkflowState.EXCEPTION);
+            workplaceStore.commitContext(latestContext.name(), latestContext, false);
+        } catch (StorageException e) {
+            log.error("Exception: ", e);
+            // StorageException does not commit context.
+        } catch (Exception e) {
+            log.error("Exception: ", e);
+            latestContext.setCause(e.getMessage());
+            latestContext.setState(WorkflowState.EXCEPTION);
+            workplaceStore.commitContext(latestContext.name(), latestContext, false);
+        }
+
+        return latestContext;
+    }
+
+    /**
+     * Execute workplace.
+     * @param workplace workplace
+     * @return workplace
+     */
+    private Workplace execWorkplace(Workplace workplace) {
+
+        return null;
+    }
+
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowAccumulator.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowAccumulator.java
new file mode 100644
index 0000000..d13b66f
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowAccumulator.java
@@ -0,0 +1,82 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl;
+
+import com.google.common.collect.Maps;
+import org.onlab.util.AbstractAccumulator;
+import org.onosproject.workflow.api.WorkflowData;
+import org.onosproject.workflow.api.WorkflowBatchDelegate;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Timer;
+
+/**
+ * An accumulator for building batches of workflow operations. Only one batch should
+ * be in process per instance at a time.
+ */
+public class WorkflowAccumulator extends AbstractAccumulator<WorkflowData> {
+
+    private static final int DEFAULT_MAX_EVENTS = 1000;
+    private static final int DEFAULT_MAX_IDLE_MS = 10;
+    private static final int DEFAULT_MAX_BATCH_MS = 50;
+
+    private static final Timer TIMER = new Timer("onos-workflow-op-batching");
+
+    private final WorkflowBatchDelegate delegate;
+
+    private volatile boolean ready;
+
+    /**
+     * Creates an intent operation accumulator.
+     *
+     * @param delegate the intent batch delegate
+     */
+    protected WorkflowAccumulator(WorkflowBatchDelegate delegate) {
+        super(TIMER, DEFAULT_MAX_EVENTS, DEFAULT_MAX_BATCH_MS, DEFAULT_MAX_IDLE_MS);
+        this.delegate = delegate;
+        // Assume that the delegate is ready for worklettype at the start
+        ready = true; //TODO validate the assumption that delegate is ready
+    }
+
+    @Override
+    public void processItems(List<WorkflowData> items) {
+        ready = false;
+        delegate.execute(reduce(items));
+    }
+
+    private Collection<WorkflowData> reduce(List<WorkflowData> ops) {
+        Map<String, WorkflowData> map = Maps.newHashMap();
+        for (WorkflowData op : ops) {
+            map.put(op.name(), op);
+        }
+        //TODO check the version... or maybe workplaceStore will handle this.
+        return map.values();
+    }
+
+    @Override
+    public boolean isReady() {
+        return ready;
+    }
+
+    /**
+     * Making accumulator to be ready.
+     */
+    public void ready() {
+        ready = true;
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowManager.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowManager.java
new file mode 100644
index 0000000..66bd709
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowManager.java
@@ -0,0 +1,282 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl;
+
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.JsonNodeType;
+import com.fasterxml.jackson.databind.node.MissingNode;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onosproject.net.config.NetworkConfigRegistry;
+import org.onosproject.net.config.NetworkConfigService;
+import org.onosproject.workflow.api.WorkflowService;
+import org.onosproject.workflow.api.WorkflowExecutionService;
+import org.onosproject.workflow.api.WorkplaceStore;
+import org.onosproject.workflow.api.WorkflowStore;
+import org.onosproject.workflow.api.WorkplaceDescription;
+import org.onosproject.workflow.api.WorkflowException;
+import org.onosproject.workflow.api.DefaultWorkplace;
+import org.onosproject.workflow.api.JsonDataModelTree;
+import org.onosproject.workflow.api.WorkflowDescription;
+import org.onosproject.workflow.api.Workplace;
+import org.onosproject.workflow.api.WorkflowDataModelException;
+import org.onosproject.workflow.api.Workflow;
+import org.onosproject.workflow.api.Worklet;
+import org.onosproject.workflow.api.WorkflowContext;
+import org.onosproject.workflow.api.JsonDataModel;
+import org.slf4j.Logger;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Field;
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+@Component(immediate = true)
+public class WorkflowManager implements WorkflowService {
+
+    protected static final Logger log = getLogger(WorkflowManager.class);
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private WorkflowExecutionService workflowExecutionService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkplaceStore workplaceStore;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkflowStore workflowStore;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private NetworkConfigService networkConfigService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    private NetworkConfigRegistry networkConfigRegistry;
+
+    private WorkflowNetConfigListener netcfgListener;
+
+    @Activate
+    public void activate() {
+        netcfgListener = new WorkflowNetConfigListener(this);
+        networkConfigRegistry.registerConfigFactory(netcfgListener.getConfigFactory());
+        networkConfigService.addListener(netcfgListener);
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        networkConfigService.removeListener(netcfgListener);
+        networkConfigRegistry.unregisterConfigFactory(netcfgListener.getConfigFactory());
+        log.info("Stopped");
+    }
+
+    @Override
+    public void createWorkplace(WorkplaceDescription wpDesc) throws WorkflowException {
+        log.info("createWorkplace: {}", wpDesc);
+
+        JsonNode root;
+        if (wpDesc.data().isPresent()) {
+            root = wpDesc.data().get();
+        } else {
+            root = JsonNodeFactory.instance.objectNode();
+        }
+        DefaultWorkplace workplace =
+                new DefaultWorkplace(wpDesc.name(), new JsonDataModelTree(root));
+        workplaceStore.registerWorkplace(wpDesc.name(), workplace);
+    }
+
+    @Override
+    public void removeWorkplace(WorkplaceDescription wpDesc) throws WorkflowException {
+        log.info("removeWorkplace: {}", wpDesc);
+        //TODO: Removing workflows belong to this workplace
+        workplaceStore.removeWorkplace(wpDesc.name());
+    }
+
+    @Override
+    public void clearWorkplace() throws WorkflowException {
+        log.info("clearWorkplace");
+        workplaceStore.getWorkplaces().stream()
+                .filter(wp -> !Objects.equals(wp.name(), Workplace.SYSTEM_WORKPLACE))
+                .forEach(wp -> workplaceStore.removeWorkplace(wp.name()));
+    }
+
+    @Override
+    public void invokeWorkflow(WorkflowDescription wfDesc) throws WorkflowException {
+        invokeWorkflow(wfDesc.toJson());
+    }
+
+    @Override
+    public void invokeWorkflow(JsonNode worklowDescJson) throws WorkflowException {
+        log.info("invokeWorkflow: {}", worklowDescJson);
+        Workplace workplace = workplaceStore.getWorkplace(Workplace.SYSTEM_WORKPLACE);
+        if (Objects.isNull(workplace)) {
+            throw new WorkflowException("Invalid system workplace");
+        }
+
+        Workflow workflow = workflowStore.get(URI.create(worklowDescJson.get("id").asText()));
+        if (Objects.isNull(workflow)) {
+            throw new WorkflowException("Invalid Workflow");
+        }
+
+        checkWorkflowSchema(workflow, worklowDescJson);
+
+        Workflow wfCreationWf = workflowStore.get(URI.create(WorkplaceWorkflow.WF_CREATE_WORKFLOW));
+        if (Objects.isNull(wfCreationWf)) {
+            throw new WorkflowException("Invalid workflow " + WorkplaceWorkflow.WF_CREATE_WORKFLOW);
+        }
+
+        WorkflowContext context = wfCreationWf.buildSystemContext(workplace, new JsonDataModelTree(worklowDescJson));
+        workflowExecutionService.execInitWorklet(context);
+    }
+
+    /**
+     * Checks if the type of worklet is same as that of wfdesc Json.
+     *
+     * @param workflow workflow
+     * @param worklowDescJson jsonNode
+     * @throws WorkflowException workflow exception
+     */
+    private void checkWorkflowSchema(Workflow workflow, JsonNode worklowDescJson) throws WorkflowException {
+
+        List<String> errors = new ArrayList<>();
+
+        JsonNode dataNode = worklowDescJson.get("data");
+        if (Objects.isNull(dataNode) || dataNode instanceof MissingNode) {
+            errors.add("workflow description json does not have 'data'");
+            throw new WorkflowDataModelException(workflow.id(), worklowDescJson, errors);
+        }
+
+        for (String workletType : workflow.getWorkletTypeList()) {
+
+            Worklet worklet = workflow.getWorkletInstance(workletType);
+            if (Worklet.Common.COMPLETED.equals(worklet) || Worklet.Common.INIT.equals(worklet)) {
+                continue;
+            }
+
+            Class cls = worklet.getClass();
+            for (Field field : cls.getDeclaredFields()) {
+
+                if (field.isSynthetic()) {
+                    continue;
+                }
+
+                for (Annotation annotation : field.getAnnotations()) {
+
+                    if (annotation instanceof JsonDataModel) {
+
+                        JsonDataModel jsonDataModel = (JsonDataModel) annotation;
+                        Matcher matcher = Pattern.compile("(\\w+)").matcher(jsonDataModel.path());
+                        if (!matcher.find()) {
+                            throw new WorkflowException(
+                                    "Invalid Json Data Model Path(" + jsonDataModel.path() + ") in " + worklet.tag());
+                        }
+                        String path = matcher.group(1);
+
+                        Optional<String> optError =
+                                getJsonNodeDataError(dataNode, worklet, field, path, jsonDataModel.optional());
+
+                        if (optError.isPresent()) {
+                            errors.add(optError.get());
+                        }
+                    }
+                }
+            }
+        }
+
+        if (!errors.isEmpty()) {
+            throw new WorkflowDataModelException(workflow.id(), worklowDescJson, errors);
+        }
+    }
+
+    private Optional<String> getJsonNodeDataError(
+            JsonNode dataNode, Worklet worklet, Field field, String path, boolean isOptional) throws WorkflowException {
+
+        // Checking the existence of path in dataNode
+        JsonNode pathNode = dataNode.get(path);
+        if (Objects.isNull(pathNode) || pathNode instanceof MissingNode) {
+
+            if (isOptional) {
+                return Optional.empty();
+
+            } else {
+                return Optional.of("data doesn't have '" + path + "' in worklet<" + worklet.tag() + ">");
+            }
+        }
+
+        // Checking the type of path
+        JsonNodeType type = pathNode.getNodeType();
+
+        if (Objects.isNull(type)) {
+            throw new WorkflowException("Invalid type for " + pathNode);
+        }
+
+        switch (type) {
+            case NUMBER:
+                if (!(field.getType().isAssignableFrom(Integer.class))) {
+                    return Optional.of("'" + path + "<NUMBER>' cannot be assigned to " +
+                            field.getName() + "<" + field.getType() + "> in worklet<" + worklet.tag() + ">");
+                }
+                break;
+            case STRING:
+                if (!(field.getType().isAssignableFrom(String.class))) {
+                    return Optional.of("'" + path + "<STRING>' cannot be assigned to " +
+                            field.getName() + "<" + field.getType() + "> in worklet<" + worklet.tag() + ">");
+                }
+                break;
+            case BOOLEAN:
+                if (!(field.getType().isAssignableFrom(Boolean.class))) {
+                    return Optional.of("'" + path + "<BOOLEAN>' cannot be assigned to " +
+                            field.getName() + "<" + field.getType() + "> in worklet<" + worklet.tag() + ">");
+                }
+                break;
+            case OBJECT:
+                if (!(field.getType().isAssignableFrom(JsonNode.class))) {
+                    return Optional.of("'" + path + "<OBJECT>' cannot be assigned to " +
+                            field.getName() + "<" + field.getType() + "> in worklet<" + worklet.tag() + ">");
+                }
+                break;
+            case ARRAY:
+                if (!(field.getType().isAssignableFrom(ArrayNode.class))) {
+                    return Optional.of("'" + path + "<ARRAY>' cannot be assigned to " +
+                            field.getName() + "<" + field.getType() + "> in worklet<" + worklet.tag() + ">");
+                }
+                break;
+            default:
+                return Optional.of("'" + path + "<" + type + ">' is not supported");
+        }
+
+        return Optional.empty();
+    }
+
+    @Override
+    public void terminateWorkflow(WorkflowDescription wfDesc) throws WorkflowException {
+        log.info("terminateWorkflow: {}", wfDesc);
+        if (Objects.nonNull(workplaceStore.getContext(wfDesc.workflowContextName()))) {
+            workplaceStore.removeContext(wfDesc.workflowContextName());
+        }
+    }
+}
\ No newline at end of file
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowNetConfig.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowNetConfig.java
new file mode 100644
index 0000000..2bca555
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowNetConfig.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.net.config.Config;
+import org.onosproject.workflow.api.DefaultRpcDescription;
+import org.onosproject.workflow.api.RpcDescription;
+import org.onosproject.workflow.api.WorkflowException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+
+public class WorkflowNetConfig extends Config<ApplicationId> {
+
+    private static final Logger log = LoggerFactory.getLogger(WorkflowNetConfig.class);
+
+    /**
+     * Workflow RPC pointer.
+     */
+    private static final String RPC_PTR = "/rpc";
+
+    public Collection<RpcDescription> getRpcDescriptions() throws WorkflowException {
+
+        JsonNode node = object.at(RPC_PTR);
+        if (!(node instanceof ArrayNode)) {
+            throw new WorkflowException("invalid rpc for " + object);
+        }
+        ArrayNode rpcArrayNode = (ArrayNode) node;
+
+        List<RpcDescription> rpcDescriptions = new ArrayList<>();
+        for (JsonNode rpcNode : rpcArrayNode) {
+            rpcDescriptions.add(DefaultRpcDescription.valueOf(rpcNode));
+        }
+
+        return rpcDescriptions;
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowNetConfigListener.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowNetConfigListener.java
new file mode 100644
index 0000000..bb7f875
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkflowNetConfigListener.java
@@ -0,0 +1,140 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl;
+
+import org.onosproject.core.ApplicationId;
+import org.onosproject.net.config.ConfigFactory;
+import org.onosproject.net.config.NetworkConfigEvent;
+import org.onosproject.net.config.NetworkConfigListener;
+import org.onosproject.net.config.basics.SubjectFactories;
+import org.onosproject.workflow.api.DefaultWorkflowDescription;
+import org.onosproject.workflow.api.RpcDescription;
+import org.onosproject.workflow.api.WorkflowService;
+import org.onosproject.workflow.api.WorkflowException;
+import org.onosproject.workflow.api.DefaultWorkplaceDescription;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ScheduledExecutorService;
+
+import static java.util.concurrent.Executors.newSingleThreadScheduledExecutor;
+import static org.onlab.util.Tools.groupedThreads;
+
+public class WorkflowNetConfigListener implements NetworkConfigListener {
+
+    private static final Logger log = LoggerFactory.getLogger(WorkflowNetConfigListener.class);
+
+    public static final String CONFIG_KEY = "workflow";
+    public static final String EXECUTOR_GROUPNAME = "onos/workflow-netcfg";
+    public static final String EXECUTOR_PATTERN = "netcfg-event-handler";
+
+    private final ConfigFactory<ApplicationId, WorkflowNetConfig> configFactory =
+            new ConfigFactory<ApplicationId, WorkflowNetConfig>(
+                    SubjectFactories.APP_SUBJECT_FACTORY, WorkflowNetConfig.class, CONFIG_KEY) {
+                @Override
+                public WorkflowNetConfig createConfig() {
+                    return new WorkflowNetConfig();
+                }
+            };
+
+    private final WorkflowService workflowService;
+
+    private final ScheduledExecutorService executor =
+            newSingleThreadScheduledExecutor(groupedThreads(EXECUTOR_GROUPNAME, EXECUTOR_PATTERN));
+
+    public WorkflowNetConfigListener(WorkflowService workflowService) {
+        this.workflowService = workflowService;
+    }
+
+    public ConfigFactory<ApplicationId, WorkflowNetConfig> getConfigFactory() {
+        return configFactory;
+    }
+
+    @Override
+    public boolean isRelevant(NetworkConfigEvent event) {
+        return event.config().isPresent() && event.config().get() instanceof WorkflowNetConfig;
+    }
+
+    @Override
+    public void event(NetworkConfigEvent event) {
+        log.info("Configuration event: {}", event);
+        switch (event.type()) {
+            case CONFIG_ADDED:
+            case CONFIG_UPDATED:
+                if (!event.config().isPresent()) {
+                    log.error("No configuration found");
+                    return;
+                }
+                WorkflowNetConfig config = (WorkflowNetConfig) event.config().get();
+
+                //Single thread executor(locking is not required)
+                executor.execute(new Handler(workflowService, config));
+                break;
+            default:
+                break;
+        }
+    }
+
+    public static class Handler implements Runnable {
+
+        private WorkflowService workflowService;
+        private WorkflowNetConfig config;
+
+        public Handler(WorkflowService workflowService, WorkflowNetConfig config) {
+            this.workflowService = workflowService;
+            this.config = config;
+        }
+
+        @Override
+        public void run() {
+
+            try {
+                Collection<RpcDescription> rpcs = config.getRpcDescriptions();
+                log.info("" + rpcs);
+                for (RpcDescription rpc : rpcs) {
+                    if (!rpcMap.containsKey(rpc.op())) {
+                        log.error("Invalid RPC: {}", rpc);
+                        continue;
+                    }
+
+                    rpcMap.get(rpc.op()).apply(this.workflowService, rpc);
+                }
+            } catch (WorkflowException e) {
+                log.error("Exception: ", e);
+            }
+        }
+    }
+
+    @FunctionalInterface
+    public interface RpcCall {
+        void apply(WorkflowService workflowService, RpcDescription rpcDesc) throws WorkflowException;
+    }
+
+    private static Map<String, RpcCall> rpcMap = new HashMap<>();
+    static {
+        rpcMap.put("workplace.create",
+                (service, desc) -> service.createWorkplace(DefaultWorkplaceDescription.valueOf(desc.params())));
+        rpcMap.put("workplace.remove",
+                (service, desc) -> service.removeWorkplace(DefaultWorkplaceDescription.valueOf(desc.params())));
+        rpcMap.put("workflow.invoke",
+                (service, desc) -> service.invokeWorkflow(desc.params()));
+        rpcMap.put("workflow.terminate",
+                (service, desc) -> service.terminateWorkflow(DefaultWorkflowDescription.valueOf(desc.params())));
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkplaceWorkflow.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkplaceWorkflow.java
new file mode 100644
index 0000000..219436c
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/WorkplaceWorkflow.java
@@ -0,0 +1,222 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.BooleanNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onosproject.event.Event;
+import org.onosproject.workflow.api.AbstractWorklet;
+import org.onosproject.workflow.api.DefaultWorkflowContext;
+import org.onosproject.workflow.api.DefaultWorkplace;
+import org.onosproject.workflow.api.ImmutableListWorkflow;
+import org.onosproject.workflow.api.JsonDataModelTree;
+import org.onosproject.workflow.api.SystemWorkflowContext;
+import org.onosproject.workflow.api.Workflow;
+import org.onosproject.workflow.api.WorkflowAttribute;
+import org.onosproject.workflow.api.WorkflowContext;
+import org.onosproject.workflow.api.WorkflowData;
+import org.onosproject.workflow.api.WorkflowDataEvent;
+import org.onosproject.workflow.api.DefaultWorkflowDescription;
+import org.onosproject.workflow.api.WorkflowDescription;
+import org.onosproject.workflow.api.WorkflowException;
+import org.onosproject.workflow.api.WorkflowExecutionService;
+import org.onosproject.workflow.api.WorkflowStore;
+import org.onosproject.workflow.api.Workplace;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.net.URI;
+import java.util.Objects;
+
+import static org.onosproject.workflow.api.WorkflowDataEvent.Type.INSERT;
+
+public class WorkplaceWorkflow {
+
+    private static final Logger log = LoggerFactory.getLogger(WorkplaceWorkflow.class);
+
+    private WorkflowExecutionService workflowExecutionService;
+    private WorkflowStore workflowStore;
+
+    public WorkplaceWorkflow(WorkflowExecutionService workflowExecutionService,
+                             WorkflowStore workflowStore) {
+        this.workflowExecutionService = workflowExecutionService;
+        this.workflowStore = workflowStore;
+    }
+
+    public static final String WF_CREATE_WORKFLOW = "workplace.create-workflow";
+
+    public void registerWorkflows() {
+
+        Workflow workflow = ImmutableListWorkflow.builder()
+                .id(URI.create(WF_CREATE_WORKFLOW))
+                .attribute(WorkflowAttribute.REMOVE_AFTER_COMPLETE)
+                .init(ChangeDistributor.class.getName())
+                .chain(CreateWorkplace.class.getName())
+                .chain(CreateWorkflowContext.class.getName())
+                .build();
+        workflowStore.register(workflow);
+    }
+
+    public abstract static class AbsWorkflowWorklet extends AbstractWorklet {
+
+        protected WorkflowDescription getWorkflowDesc(WorkflowContext context) throws WorkflowException {
+
+            JsonNode root = ((JsonDataModelTree) context.data()).root();
+            return DefaultWorkflowDescription.valueOf(root);
+        }
+    }
+
+    public static class ChangeDistributor extends AbsWorkflowWorklet {
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            String workplaceName = getWorkflowDesc(context).workplaceName();
+            // Sets workflow job distribution hash value to make this workflow to be executed on the
+            // same cluster node to execute workplace tasks.
+            ((SystemWorkflowContext) context).setDistributor(workplaceName);
+
+            context.completed();
+       }
+    }
+
+    public static class CreateWorkplace extends AbsWorkflowWorklet {
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            WorkflowDescription wfDesc = getWorkflowDesc(context);
+
+            Workplace workplace = context.workplaceStore().getWorkplace(wfDesc.workplaceName());
+            return Objects.isNull(workplace);
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            WorkflowDescription wfDesc = getWorkflowDesc(context);
+
+            // creates workplace with empty data model
+            DefaultWorkplace workplace = new DefaultWorkplace(wfDesc.workplaceName(), new JsonDataModelTree());
+            log.info("registerWorkplace {}", workplace);
+            context.waitCompletion(WorkflowDataEvent.class, wfDesc.workplaceName(),
+                    () -> context.workplaceStore().registerWorkplace(wfDesc.workplaceName(), workplace),
+                    60000L
+            );
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+
+            if (!(event instanceof WorkflowDataEvent)) {
+                return false;
+            }
+
+            WorkflowDataEvent wfEvent = (WorkflowDataEvent) event;
+            WorkflowData wfData = wfEvent.subject();
+
+            WorkflowDescription wfDesc = getWorkflowDesc(context);
+
+            if (wfData instanceof Workplace
+                    && Objects.equals(wfData.name(), wfDesc.workplaceName())
+                    && wfEvent.type() == INSERT) {
+                log.info("isCompleted(true): event:{}, context:{}, workplace:{}",
+                        event, context, wfDesc.workplaceName());
+                return true;
+            } else {
+                log.info("isCompleted(false) event:{}, context:{}, workplace:{}",
+                        event, context, wfDesc.workplaceName());
+                return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete the job of worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+    }
+
+    public static class CreateWorkflowContext extends AbsWorkflowWorklet {
+
+        private static final String SUBMITTED = "submitted";
+
+        private boolean isSubmitted(WorkflowContext context) throws WorkflowException {
+            JsonNode node = ((JsonDataModelTree) context.data()).nodeAt("/" + SUBMITTED);
+            if (!(node instanceof BooleanNode)) {
+                return false;
+            }
+            return node.asBoolean();
+        }
+
+        private void submitTrue(WorkflowContext context) throws WorkflowException {
+            JsonNode root = ((JsonDataModelTree) context.data()).root();
+            if (!(root instanceof ObjectNode)) {
+                throw new WorkflowException("Invalid root node for " + context);
+            }
+            ((ObjectNode) root).put(SUBMITTED, true);
+        }
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            WorkflowDescription wfDesc = getWorkflowDesc(context);
+
+            String contextName = DefaultWorkflowContext.nameBuilder(wfDesc.id(), wfDesc.workplaceName());
+            if (Objects.isNull(context.workplaceStore().getContext(contextName))) {
+                return (!isSubmitted(context));
+            } else {
+                return false;
+            }
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            WorkflowDescription wfDesc = getWorkflowDesc(context);
+
+            Workplace workplace = context.workplaceStore().getWorkplace(wfDesc.workplaceName());
+            if (Objects.isNull(workplace)) {
+
+                log.error("Failed to find workplace with " + wfDesc.workplaceName());
+                throw new WorkflowException("Failed to find workplace with " + wfDesc.workplaceName());
+            }
+
+            Workflow workflow = context.workflowStore().get(wfDesc.id());
+            if (Objects.isNull(workflow)) {
+                throw new WorkflowException("Failed to find workflow with " + wfDesc.id());
+            }
+
+            //String contextName = DefaultWorkflowContext.nameBuilder(wfDesc.id(), wfDesc.workplaceName());
+            String contextName = wfDesc.workflowContextName();
+            if (Objects.nonNull(context.workplaceStore().getContext(contextName))) {
+                throw new WorkflowException(contextName + " exists already");
+            }
+
+            JsonDataModelTree subTree = new JsonDataModelTree(wfDesc.data());
+            WorkflowContext buildingContext = workflow.buildContext(workplace, subTree);
+            log.info("registerContext {}", buildingContext.name());
+            context.workplaceStore().registerContext(buildingContext.name(), buildingContext);
+            submitTrue(context);
+
+            context.completed();
+        }
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/example/SampleWorkflow.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/example/SampleWorkflow.java
new file mode 100644
index 0000000..9da6d60
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/example/SampleWorkflow.java
@@ -0,0 +1,345 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.impl.example;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.JsonNodeType;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.workflow.api.AbstractWorklet;
+import org.onosproject.workflow.api.DataModelTree;
+import org.onosproject.workflow.api.ImmutableListWorkflow;
+import org.onosproject.workflow.api.JsonDataModel;
+import org.onosproject.workflow.api.JsonDataModelTree;
+import org.onosproject.workflow.api.Workflow;
+import org.onosproject.workflow.api.WorkflowContext;
+import org.onosproject.workflow.api.WorkflowException;
+import org.onosproject.workflow.api.WorkflowExecutionService;
+import org.onosproject.workflow.api.WorkflowStore;
+import org.onosproject.workflow.api.WorkplaceStore;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.net.URI;
+
+/**
+ * Class for sample workflow.
+ */
+@Component(immediate = true)
+public class SampleWorkflow {
+
+    private static final Logger log = LoggerFactory.getLogger(SampleWorkflow.class);
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkflowStore workflowStore;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkplaceStore workplaceStore;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkflowExecutionService workflowExecutionService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected DeviceService deviceService;
+
+
+    @Activate
+    public void activate() {
+        log.info("Activated");
+
+        registerWorkflows();
+
+    }
+
+    @Deactivate
+    public void deactivate() {
+        log.info("Deactivated");
+    }
+
+    /**
+     * Registers example workflows.
+     */
+    private void registerWorkflows() {
+        // registering class-loader
+        workflowStore.registerLocal(this.getClass().getClassLoader());
+
+        // registering new workflow definition
+        URI uri = URI.create("sample.workflow-0");
+        Workflow workflow = ImmutableListWorkflow.builder()
+                .id(uri)
+                .chain(SampleWorklet1.class.getName())
+                .chain(SampleWorklet2.class.getName())
+                .chain(SampleWorklet3.class.getName())
+                .chain(SampleWorklet4.class.getName())
+                .chain(SampleWorklet5.class.getName())
+                .build();
+        workflowStore.register(workflow);
+
+        // registering new workflow definition
+        uri = URI.create("sample.workflow-1");
+        workflow = ImmutableListWorkflow.builder()
+                .id(uri)
+                .chain(SampleWorklet3.class.getName())
+                .chain(SampleWorklet2.class.getName())
+                .chain(SampleWorklet1.class.getName())
+                .chain(SampleWorklet4.class.getName())
+                .chain(SampleWorklet5.class.getName())
+                .build();
+        workflowStore.register(workflow);
+
+        // registering new workflow definition
+        uri = URI.create("sample.workflow-2");
+        workflow = ImmutableListWorkflow.builder()
+                .id(uri)
+                .chain(SampleWorklet1.class.getName())
+                .chain(SampleWorklet3.class.getName())
+                .chain(SampleWorklet2.class.getName())
+                .chain(SampleWorklet4.class.getName())
+                .chain(SampleWorklet5.class.getName())
+                .build();
+        workflowStore.register(workflow);
+
+        // registering new workflow definition
+        uri = URI.create("sample.workflow-3");
+        workflow = ImmutableListWorkflow.builder()
+                .id(uri)
+                .chain(SampleWorklet6.class.getName())
+                .build();
+        workflowStore.register(workflow);
+
+    }
+
+    /**
+     * Abstract class for sample worklet.
+     */
+    public abstract static class AbsSampleWorklet extends AbstractWorklet {
+
+        protected static final String MODEL_SAMPLE_JOB = "/sample/job";
+        protected static final String MODEL_COUNT = "/count";
+
+        /**
+         * Constructor for sample worklet.
+         */
+        protected AbsSampleWorklet() {
+
+        }
+
+        /**
+         * Allocates or gets data model.
+         * @param context workflow context
+         * @return json object node
+         * @throws WorkflowException workflow exception
+         */
+        protected ObjectNode allocOrGetModel(WorkflowContext context) throws WorkflowException {
+
+            JsonDataModelTree tree = (JsonDataModelTree) context.data();
+            JsonNode params = tree.root();
+
+            if (params.at(MODEL_SAMPLE_JOB).getNodeType() == JsonNodeType.MISSING) {
+                tree.alloc(MODEL_SAMPLE_JOB, DataModelTree.Nodetype.MAP);
+            }
+            return (ObjectNode) params.at(MODEL_SAMPLE_JOB);
+        }
+
+        /**
+         * Gets data model.
+         * @param context workflow context
+         * @return json object node
+         * @throws WorkflowException workflow exception
+         */
+        protected ObjectNode getDataModel(WorkflowContext context) throws WorkflowException {
+            DataModelTree tree = context.data();
+            return ((JsonDataModelTree) tree.subtree(MODEL_SAMPLE_JOB)).rootObject();
+        }
+
+        /**
+         * Sleeps for 'ms' milli seconds.
+         * @param ms milli seconds to sleep
+         */
+        protected void sleep(long ms) {
+            try {
+                Thread.sleep(ms);
+            } catch (InterruptedException e) {
+                log.error("Exception: ", e);
+                Thread.currentThread().interrupt();
+            }
+        }
+    }
+
+    /**
+     * Class for sample worklet-1.
+     */
+    public static class SampleWorklet1 extends AbsSampleWorklet {
+
+        @JsonDataModel(path = MODEL_COUNT)
+        Integer intCount;
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = getDataModel(context);
+            node.put("work1", "done");
+            log.info("workflow-process {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(30);
+
+            context.completed(); //Complete the job of worklet in the process
+        }
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = allocOrGetModel(context);
+            log.info("workflow-isNext {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(30);
+            return !node.has("work1");
+
+        }
+    }
+
+    /**
+     * Class for sample worklet-2 (using timeout).
+     */
+    public static class SampleWorklet2 extends AbsSampleWorklet {
+
+        @JsonDataModel(path = MODEL_COUNT)
+        Integer intCount;
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = getDataModel(context);
+            node.put("work2", "done");
+            log.info("workflow-process {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(50);
+            intCount++;
+
+            context.waitFor(50L); //Timeout will happen after 50 milli seconds.
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            context.completed(); //Complete the job of worklet by timeout
+        }
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = allocOrGetModel(context);
+            log.info("workflow-isNext {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(50);
+            return !node.has("work2");
+        }
+    }
+
+    public static class SampleWorklet3 extends AbsSampleWorklet {
+
+        @JsonDataModel(path = MODEL_COUNT)
+        Integer intCount;
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = getDataModel(context);
+            node.put("work3", "done");
+            log.info("workflow-process {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(10);
+            intCount++;
+            context.completed();
+        }
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = allocOrGetModel(context);
+            log.info("workflow-isNext {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(10);
+            return !node.has("work3");
+        }
+    }
+
+    public static class SampleWorklet4 extends AbsSampleWorklet {
+
+        @JsonDataModel(path = MODEL_COUNT)
+        Integer intCount;
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = getDataModel(context);
+            node.put("work4", "done");
+            log.info("workflow-process {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(10);
+            intCount++;
+            context.completed();
+        }
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = allocOrGetModel(context);
+            log.info("workflow-isNext {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(10);
+            return !node.has("work4");
+        }
+    }
+
+    public static class SampleWorklet5 extends AbsSampleWorklet {
+
+        @JsonDataModel(path = MODEL_COUNT)
+        Integer intCount;
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = getDataModel(context);
+            node.put("work5", "done");
+            log.info("workflow-process {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(10);
+            intCount++;
+            context.completed();
+        }
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = allocOrGetModel(context);
+            log.info("workflow-isNext {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(10);
+            return !node.has("work5");
+        }
+    }
+
+    /**
+     * Class for sample worklet-6 to test workflow datamodel exception.
+     */
+    public static class SampleWorklet6 extends AbsSampleWorklet {
+
+        @JsonDataModel(path = MODEL_COUNT)
+        String str;
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = getDataModel(context);
+            node.put("work6", "done");
+            log.info("workflow-process {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(10);
+            context.completed();
+        }
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+            ObjectNode node = allocOrGetModel(context);
+            log.info("workflow-isNext {}-{}", context.workplaceName(), this.getClass().getSimpleName());
+            sleep(10);
+            return !node.has("work6");
+        }
+    }
+}
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/example/package-info.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/example/package-info.java
new file mode 100644
index 0000000..2fbc9549a
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/example/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Workflow example package.
+ */
+package org.onosproject.workflow.impl.example;
\ No newline at end of file
diff --git a/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/package-info.java b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/package-info.java
new file mode 100644
index 0000000..f82c452
--- /dev/null
+++ b/apps/workflow/app/src/main/java/org/onosproject/workflow/impl/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Workflow implementation package.
+ */
+package org.onosproject.workflow.impl;
\ No newline at end of file
diff --git a/apps/workflow/model/BUCK b/apps/workflow/model/BUCK
new file mode 100644
index 0000000..a1c6f0b
--- /dev/null
+++ b/apps/workflow/model/BUCK
@@ -0,0 +1,12 @@
+COMPILE_DEPS = [
+    '//lib:CORE_DEPS',
+    '//lib:jackson-core',
+    '//lib:jackson-annotations',
+    '//lib:jackson-databind',
+    '//core/store/serializers:onos-core-serializers',
+    '//apps/workflow/api:onos-apps-workflow-api',
+]
+
+osgi_jar_with_tests(
+    deps = COMPILE_DEPS,
+)
diff --git a/apps/workflow/model/BUILD b/apps/workflow/model/BUILD
new file mode 100644
index 0000000..016e14a
--- /dev/null
+++ b/apps/workflow/model/BUILD
@@ -0,0 +1,8 @@
+COMPILE_DEPS = CORE_DEPS + KRYO + JACKSON + [
+    "//core/store/serializers:onos-core-serializers",
+    "//apps/workflow/api:onos-apps-workflow-api",
+]
+
+osgi_jar_with_tests(
+    deps = COMPILE_DEPS,
+)
diff --git a/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/NetconfAccessInfo.java b/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/NetconfAccessInfo.java
new file mode 100644
index 0000000..8e428e3
--- /dev/null
+++ b/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/NetconfAccessInfo.java
@@ -0,0 +1,165 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.model.accessinfo;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.NumericNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+import com.google.common.base.MoreObjects;
+import org.onlab.packet.IpAddress;
+import org.onlab.packet.TpPort;
+import org.onosproject.workflow.api.WorkflowException;
+
+import java.util.Objects;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Class for NETCONF access information.
+ */
+public final class NetconfAccessInfo {
+
+    private static final String REMOTE_IP = "remoteIp";
+    private static final String PORT = "port";
+    private static final String USER = "user";
+    private static final String PASSWORD = "password";
+
+    private final IpAddress remoteIp;
+    private final TpPort port;
+    private final String user;
+    private final String password;
+
+    /**
+     * Constructor for a given NETCONF access information.
+     *
+     * @param remoteIp remote ip address
+     * @param port port number
+     * @param user user name
+     * @param password password
+     */
+    public NetconfAccessInfo(IpAddress remoteIp,
+                             TpPort port,
+                             String user,
+                             String password) {
+        this.remoteIp = checkNotNull(remoteIp);
+        this.port = checkNotNull(port);
+        this.user = checkNotNull(user);
+        this.password = checkNotNull(password);
+    }
+
+    /**
+     * Builds NetconfAccessInfo from json.
+     * @param root json root node for NetconfAccessinfo
+     * @return NETCONF access information
+     * @throws WorkflowException workflow exception
+     */
+    public static NetconfAccessInfo valueOf(JsonNode root) throws WorkflowException {
+
+        JsonNode node = root.at(ptr(REMOTE_IP));
+        if (node == null || !(node instanceof TextNode)) {
+            throw new WorkflowException("invalid remoteIp for " + root);
+        }
+        IpAddress remoteIp = IpAddress.valueOf(node.asText());
+
+        node = root.at(ptr(PORT));
+        if (node == null || !(node instanceof NumericNode)) {
+            throw new WorkflowException("invalid port for " + root);
+        }
+        TpPort tpPort = TpPort.tpPort(node.asInt());
+
+        node = root.at(ptr(USER));
+        if (node == null || !(node instanceof TextNode)) {
+            throw new WorkflowException("invalid user for " + root);
+        }
+        String strUser = node.asText();
+
+        node = root.at(ptr(PASSWORD));
+        if (node == null || !(node instanceof TextNode)) {
+            throw new WorkflowException("invalid password for " + root);
+        }
+        String strPassword = node.asText();
+
+        return new NetconfAccessInfo(remoteIp, tpPort, strUser, strPassword);
+    }
+
+    private static String ptr(String field) {
+        return "/" + field;
+    }
+
+    /**
+     * Returns the remote IP address.
+     *
+     * @return ip address
+     */
+    public IpAddress remoteIp() {
+        return this.remoteIp;
+    }
+
+    /**
+     * Returns the port number.
+     *
+     * @return port
+     */
+    public TpPort port() {
+        return this.port;
+    }
+
+    /**
+     * Returns the user name.
+     *
+     * @return user name
+     */
+    public String user() {
+        return this.user;
+    }
+
+    /**
+     * Returns the password.
+     * @return password
+     */
+    public String password() {
+        return this.password;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj instanceof NetconfAccessInfo) {
+            NetconfAccessInfo that = (NetconfAccessInfo) obj;
+            return Objects.equals(remoteIp, that.remoteIp) &&
+                    Objects.equals(port, that.port) &&
+                    Objects.equals(user, that.user);
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(remoteIp, port, user);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("remoteIp", remoteIp)
+                .add("port", port)
+                .add("user", user)
+                .toString();
+    }
+}
\ No newline at end of file
diff --git a/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/RestAccessInfo.java b/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/RestAccessInfo.java
new file mode 100644
index 0000000..c13270d
--- /dev/null
+++ b/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/RestAccessInfo.java
@@ -0,0 +1,167 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.model.accessinfo;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.NumericNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+import com.google.common.base.MoreObjects;
+import org.onlab.packet.IpAddress;
+import org.onlab.packet.TpPort;
+import org.onosproject.workflow.api.WorkflowException;
+
+import java.util.Objects;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Class for REST access information.
+ */
+public final class RestAccessInfo {
+
+    private static final String REMOTE_IP = "remoteIp";
+    private static final String PORT = "port";
+    private static final String USER = "user";
+    private static final String PASSWORD = "password";
+
+    private final IpAddress remoteIp;
+    private final TpPort port;
+    private final String user;
+    private String password;
+
+    /**
+     * Creates a new REST access information.
+     *
+     * @param remoteIp remote ip address
+     * @param port port number
+     * @param user user name
+     * @param password password
+     */
+    private RestAccessInfo(IpAddress remoteIp,
+                          TpPort port,
+                          String user,
+                          String password) {
+        this.remoteIp = checkNotNull(remoteIp);
+        this.port = checkNotNull(port);
+        this.user = checkNotNull(user);
+        this.password = checkNotNull(password);
+    }
+
+    /**
+     * Builds RestAccessInfo from json.
+     * @param root json root node for RestAccessinfo
+     * @return REST access information
+     * @throws WorkflowException workflow exception
+     */
+    public static RestAccessInfo valueOf(JsonNode root) throws WorkflowException {
+
+        JsonNode node = root.at(ptr(REMOTE_IP));
+        if (node == null || !(node instanceof TextNode)) {
+            throw new WorkflowException("invalid remoteIp for " + root);
+        }
+        IpAddress remoteIp = IpAddress.valueOf(node.asText());
+
+        node = root.at(ptr(PORT));
+        if (node == null || !(node instanceof NumericNode)) {
+            throw new WorkflowException("invalid port for " + root);
+        }
+        TpPort tpPort = TpPort.tpPort(node.asInt());
+
+        node = root.at(ptr(USER));
+        if (node == null || !(node instanceof TextNode)) {
+            throw new WorkflowException("invalid user for " + root);
+        }
+        String strUser = node.asText();
+
+        node = root.at(ptr(PASSWORD));
+        if (node == null || !(node instanceof TextNode)) {
+            throw new WorkflowException("invalid password for " + root);
+        }
+        String strPassword = node.asText();
+
+        return new RestAccessInfo(remoteIp, tpPort, strUser, strPassword);
+    }
+
+    private static String ptr(String field) {
+        return "/" + field;
+    }
+
+    /**
+     * Returns the remote IP address.
+     *
+     * @return ip address
+     */
+    public IpAddress remoteIp() {
+        return this.remoteIp;
+    }
+
+    /**
+     * Returns the port number.
+     *
+     * @return REST port
+     */
+    public TpPort port() {
+        return this.port;
+    }
+
+    /**
+     * Returns the user name.
+     *
+     * @return user name
+     */
+    public String user() {
+        return this.user;
+    }
+
+    /**
+     * Returns the password.
+     *
+     * @return password
+     */
+    public String password() {
+        return this.password;
+    }
+
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj instanceof RestAccessInfo) {
+            RestAccessInfo that = (RestAccessInfo) obj;
+            return Objects.equals(remoteIp, that.remoteIp) &&
+                    Objects.equals(port, that.port) &&
+                    Objects.equals(user, that.user);
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(remoteIp, port, user);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("remoteIp", remoteIp)
+                .add("port", port)
+                .add("user", user)
+                .toString();
+    }
+}
\ No newline at end of file
diff --git a/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/SshAccessInfo.java b/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/SshAccessInfo.java
new file mode 100644
index 0000000..aec224a
--- /dev/null
+++ b/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/SshAccessInfo.java
@@ -0,0 +1,183 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.workflow.model.accessinfo;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.NumericNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+import com.google.common.base.MoreObjects;
+import org.onlab.packet.IpAddress;
+import org.onlab.packet.TpPort;
+import org.onosproject.workflow.api.WorkflowException;
+
+import java.util.Objects;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Class for SSH access information.
+ */
+public final class SshAccessInfo {
+
+    private static final String REMOTE_IP = "remoteIp";
+    private static final String PORT = "port";
+    private static final String USER = "user";
+    private static final String PASSWORD = "password";
+    private static final String KEYFILE = "keyfile";
+
+    private final IpAddress remoteIp;
+    private final TpPort port;
+    private final String user;
+    private String password;
+    private final String privateKey;
+
+    /**
+     * Constructor for SSH access information.
+     *
+     * @param remoteIp ssh remote ip address
+     * @param port ssh port number
+     * @param user user name
+     * @param password password
+     * @param privateKey path of ssh private key
+     */
+    private SshAccessInfo(IpAddress remoteIp, TpPort port, String user, String password, String privateKey) {
+        this.remoteIp = checkNotNull(remoteIp);
+        this.port = checkNotNull(port);
+        this.user = checkNotNull(user);
+        this.password = password;
+        this.privateKey = checkNotNull(privateKey);
+    }
+
+    /**
+     * Builds SshAccessInfo from json.
+     * @param root json root node for SshAccessinfo
+     * @return SSH access information
+     * @throws WorkflowException workflow exception
+     */
+    public static SshAccessInfo valueOf(JsonNode root) throws WorkflowException {
+
+        JsonNode node = root.at(ptr(REMOTE_IP));
+        if (node == null || !(node instanceof TextNode)) {
+            throw new WorkflowException("invalid remoteIp for " + root);
+        }
+        IpAddress sshIp = IpAddress.valueOf(node.asText());
+
+        node = root.at(ptr(PORT));
+        if (node == null || !(node instanceof NumericNode)) {
+            throw new WorkflowException("invalid port for " + root);
+        }
+        TpPort sshPort = TpPort.tpPort(node.asInt());
+
+        node = root.at(ptr(USER));
+        if (node == null || !(node instanceof TextNode)) {
+            throw new WorkflowException("invalid user for " + root);
+        }
+        String sshUser = node.asText();
+
+        node = root.at(ptr(PASSWORD));
+        if (node == null || !(node instanceof TextNode)) {
+            throw new WorkflowException("invalid password for " + root);
+        }
+        String sshPassword = node.asText();
+
+        node = root.at(ptr(KEYFILE));
+        if (node == null || !(node instanceof TextNode)) {
+            throw new WorkflowException("invalid keyfile for " + root);
+        }
+        String sshKeyfile = node.asText();
+
+        return new SshAccessInfo(sshIp, sshPort, sshUser, sshPassword, sshKeyfile);
+    }
+
+    private static String ptr(String field) {
+        return "/" + field;
+    }
+
+    /**
+     * Returns the remote IP address.
+     *
+     * @return ip address
+     */
+    public IpAddress remoteIp() {
+        return this.remoteIp;
+    }
+
+    /**
+     * Returns the port number.
+     *
+     * @return ssh port
+     */
+    public TpPort port() {
+        return this.port;
+    }
+
+    /**
+     * Returns the user name.
+     *
+     * @return user name
+     */
+    public String user() {
+        return this.user;
+    }
+
+    /**
+     * Returns the password.
+     * @return password
+     */
+    public String password() {
+        return this.password;
+    }
+
+    /**
+     * Returns the private key path.
+     *
+     * @return privateKey
+     */
+    public String privateKey() {
+        return privateKey;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj instanceof SshAccessInfo) {
+            SshAccessInfo that = (SshAccessInfo) obj;
+            return Objects.equals(remoteIp, that.remoteIp) &&
+                    Objects.equals(port, that.port) &&
+                    Objects.equals(user, that.user) &&
+                    Objects.equals(privateKey, that.privateKey);
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(remoteIp, port, user, privateKey);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("remoteIp", remoteIp)
+                .add("port", port)
+                .add("user", user)
+                .add("privateKey", privateKey)
+                .toString();
+    }
+}
diff --git a/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/package-info.java b/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/package-info.java
new file mode 100644
index 0000000..bc88e3b
--- /dev/null
+++ b/apps/workflow/model/src/main/java/org/onosproject/workflow/model/accessinfo/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Package for workflow common data model - access info.
+ */
+package org.onosproject.workflow.model.accessinfo;
diff --git a/apps/workflow/ofoverlay/BUCK b/apps/workflow/ofoverlay/BUCK
new file mode 100644
index 0000000..2f3fd5a
--- /dev/null
+++ b/apps/workflow/ofoverlay/BUCK
@@ -0,0 +1,18 @@
+BUNDLES = [
+    '//apps/workflow/ofoverlay/app:onos-apps-workflow-ofoverlay-app',
+]
+
+onos_app(
+    app_name = 'org.onosproject.workflow.ofoverlay',
+    category = 'Utility',
+    description = 'Openflow overaly application',
+    included_bundles = BUNDLES,
+    required_apps = [
+        'org.onosproject.openflow',
+        'org.onosproject.ovsdb',
+        'org.onosproject.drivers.ovsdb',
+        'org.onosproject.workflow',
+    ],
+    title = 'Openflow overlay',
+    url = 'http://onosproject.org',
+)
diff --git a/apps/workflow/ofoverlay/BUILD b/apps/workflow/ofoverlay/BUILD
new file mode 100644
index 0000000..cc75d82
--- /dev/null
+++ b/apps/workflow/ofoverlay/BUILD
@@ -0,0 +1,21 @@
+BUNDLES = [
+    "@jsch//jar",
+    "//protocols/ovsdb/api:onos-protocols-ovsdb-api",
+    "//protocols/ovsdb/rfc:onos-protocols-ovsdb-rfc",
+    "//apps/workflow/ofoverlay/app:onos-apps-workflow-ofoverlay-app",
+]
+
+onos_app(
+    app_name = "org.onosproject.workflow.ofoverlay",
+    category = "Utility",
+    description = "Openflow overaly application",
+    included_bundles = BUNDLES,
+    required_apps = [
+        "org.onosproject.openflow",
+        "org.onosproject.ovsdb",
+        "org.onosproject.drivers.ovsdb",
+        "org.onosproject.workflow",
+    ],
+    title = "Openflow overlay",
+    url = "http://onosproject.org",
+)
diff --git a/apps/workflow/ofoverlay/app/BUCK b/apps/workflow/ofoverlay/app/BUCK
new file mode 100644
index 0000000..ba31441d
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/BUCK
@@ -0,0 +1,20 @@
+COMPILE_DEPS = [
+    '//lib:CORE_DEPS',
+    '//lib:KRYO',
+    '//lib:jsch',
+    '//lib:org.apache.karaf.shell.console',
+    '//lib:jackson-core',
+    '//lib:jackson-annotations',
+    '//lib:jackson-databind',
+    '//cli:onos-cli',
+    '//core/store/serializers:onos-core-serializers',
+    '//core/store/primitives:onos-core-primitives',
+    '//apps/workflow/api:onos-apps-workflow-api',
+    '//apps/workflow/model:onos-apps-workflow-model',
+    '//protocols/ovsdb/api:onos-protocols-ovsdb-api',
+    '//protocols/ovsdb/rfc:onos-protocols-ovsdb-rfc',
+]
+
+osgi_jar_with_tests(
+    deps = COMPILE_DEPS,
+)
diff --git a/apps/workflow/ofoverlay/app/BUILD b/apps/workflow/ofoverlay/app/BUILD
new file mode 100644
index 0000000..d8a5fa0
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/BUILD
@@ -0,0 +1,13 @@
+COMPILE_DEPS = CORE_DEPS + KRYO + JACKSON + CLI + [
+    "//core/store/serializers:onos-core-serializers",
+    "//core/store/primitives:onos-core-primitives",
+    "//apps/workflow/api:onos-apps-workflow-api",
+    "//apps/workflow/model:onos-apps-workflow-model",
+    "@jsch//jar",
+    "//protocols/ovsdb/api:onos-protocols-ovsdb-api",
+    "//protocols/ovsdb/rfc:onos-protocols-ovsdb-rfc",
+]
+
+osgi_jar_with_tests(
+    deps = COMPILE_DEPS,
+)
diff --git a/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/OfOverlayWorkflow.java b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/OfOverlayWorkflow.java
new file mode 100644
index 0000000..8ba91be
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/OfOverlayWorkflow.java
@@ -0,0 +1,184 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.ofoverlay.impl;
+
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.workflow.api.ImmutableListWorkflow;
+import org.onosproject.workflow.api.Workflow;
+import org.onosproject.workflow.api.WorkflowExecutionService;
+import org.onosproject.workflow.api.WorkflowStore;
+import org.onosproject.workflow.api.WorkplaceStore;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.net.URI;
+import java.util.concurrent.ScheduledExecutorService;
+
+import static java.util.concurrent.Executors.newSingleThreadScheduledExecutor;
+import static org.onlab.util.Tools.groupedThreads;
+
+/**
+ * Class for Open-flow overlay configuration workflow.
+ */
+@Component(immediate = true)
+public class OfOverlayWorkflow {
+
+    private static final Logger log = LoggerFactory.getLogger(OfOverlayWorkflow.class);
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkflowStore workflowStore;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkplaceStore workplaceStore;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected WorkflowExecutionService workflowExecutionService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected DeviceService deviceService;
+
+    private ScheduledExecutorService eventMapTriggerExecutor;
+
+    @Activate
+    public void activate() {
+        log.info("Activated");
+
+        eventMapTriggerExecutor = newSingleThreadScheduledExecutor(
+                groupedThreads("onos/of-overlay", "eventmap-trigger-executor"));
+
+        registerWorkflows();
+
+    }
+
+    @Deactivate
+    public void deactivate() {
+        log.info("Deactivated");
+    }
+
+    /**
+     * Registers workflows.
+     */
+    private void registerWorkflows() {
+        // registering class-loader
+        workflowStore.registerLocal(this.getClass().getClassLoader());
+
+        // registering new workflow definition
+        URI uri = URI.create("of-overlay.workflow-nova");
+        Workflow workflow = ImmutableListWorkflow.builder()
+                .id(uri)
+                //.attribute(WorkflowAttribute.REMOVE_AFTER_COMPLETE)
+                .chain(Ovs.CreateOvsdbDevice.class.getName())
+                .chain(Ovs.UpdateOvsVersion.class.getName())
+                .chain(Ovs.UpdateOverlayBridgeId.class.getName())
+                .chain(Ovs.CreateOverlayBridge.class.getName())
+                .chain(Ovs.UpdateUnderlayBridgeId.class.getName())
+                .chain(Ovs.CreateUnderlayBridge.class.getName())
+                .chain(Ovs.CreateOverlayBridgeVxlanPort.class.getName())
+                .chain(Ovs.AddPhysicalPortsOnUnderlayBridge.class.getName())
+                .chain(Ovs.ConfigureUnderlayBridgeLocalIp.class.getName())
+                .build();
+        workflowStore.register(workflow);
+
+        // registering new workflow definition based on multi-event handling
+        uri = URI.create("of-overlay.workflow-nova-multiEvent-test");
+        workflow = ImmutableListWorkflow.builder()
+                .id(uri)
+                //.attribute(WorkflowAttribute.REMOVE_AFTER_COMPLETE)
+                .chain(Ovs.CreateOvsdbDevice.class.getName())
+                .chain(Ovs.UpdateOvsVersion.class.getName())
+                .chain(Ovs.UpdateOverlayBridgeId.class.getName())
+                .chain(Ovs.CreateOverlayBridgeMultiEvent.class.getName())
+                .chain(Ovs.UpdateUnderlayBridgeId.class.getName())
+                .chain(Ovs.CreateUnderlayBridge.class.getName())
+                .chain(Ovs.CreateOverlayBridgeVxlanPort.class.getName())
+                .chain(Ovs.AddPhysicalPortsOnUnderlayBridge.class.getName())
+                .chain(Ovs.ConfigureUnderlayBridgeLocalIp.class.getName())
+                .build();
+        workflowStore.register(workflow);
+
+        uri = URI.create("of-overlay.clean-workflow-nova");
+        workflow = ImmutableListWorkflow.builder()
+                .id(uri)
+                //.attribute(WorkflowAttribute.REMOVE_AFTER_COMPLETE)
+                .chain(Ovs.DeleteOverlayBridgeConfig.class.getName())
+                .chain(Ovs.RemoveOverlayBridgeOfDevice.class.getName())
+                .chain(Ovs.DeleteUnderlayBridgeConfig.class.getName())
+                .chain(Ovs.RemoveUnderlayBridgeOfDevice.class.getName())
+                .chain(Ovs.RemoveOvsdbDevice.class.getName())
+                .build();
+        workflowStore.register(workflow);
+
+        uri = URI.create("of-overlay.clean-workflow-nova-waitAll-Bridge-Del");
+        workflow = ImmutableListWorkflow.builder()
+                .id(uri)
+                //.attribute(WorkflowAttribute.REMOVE_AFTER_COMPLETE)
+                .chain(Ovs.DeleteOverlayBridgeConfig.class.getName())
+                .chain(Ovs.DeleteUnderlayBridgeConfig.class.getName())
+                .chain(Ovs.RemoveBridgeOfDevice.class.getName())
+                .chain(Ovs.RemoveOvsdbDevice.class.getName())
+                .build();
+        workflowStore.register(workflow);
+
+        uri = URI.create("of-overlay.workflow-ovs-leaf");
+        workflow = ImmutableListWorkflow.builder()
+                .id(uri)
+                .chain(Ovs.CreateOvsdbDevice.class.getName())
+                .chain(Ovs.UpdateOvsVersion.class.getName())
+                .chain(Ovs.UpdateUnderlayBridgeId.class.getName())
+                .chain(Ovs.CreateUnderlayBridge.class.getName())
+                .chain(Ovs.AddPhysicalPortsOnUnderlayBridge.class.getName())
+                .build();
+        workflowStore.register(workflow);
+
+        uri = URI.create("of-overlay.workflow-ovs-spine");
+        workflow = ImmutableListWorkflow.builder()
+                .id(uri)
+                .chain(Ovs.CreateOvsdbDevice.class.getName())
+                .chain(Ovs.UpdateOvsVersion.class.getName())
+                .chain(Ovs.UpdateUnderlayBridgeId.class.getName())
+                .chain(Ovs.CreateUnderlayBridge.class.getName())
+                .chain(Ovs.AddPhysicalPortsOnUnderlayBridge.class.getName())
+                .build();
+        workflowStore.register(workflow);
+
+        deviceService.addListener(
+                event -> {
+                    // trigger EventTask for DeviceEvent
+                    eventMapTriggerExecutor.submit(
+                            () -> workflowExecutionService.eventMapTrigger(
+                                    event,
+                                    // event hint supplier
+                                    (ev) -> {
+                                        if (ev == null || ev.subject() == null) {
+                                            return null;
+                                        }
+                                        String hint = event.subject().id().toString();
+                                        log.debug("hint: {}", hint);
+                                        return hint;
+                                    }
+                            )
+                    );
+                }
+        );
+
+    }
+
+}
diff --git a/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/Ovs.java b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/Ovs.java
new file mode 100644
index 0000000..ad56d52
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/Ovs.java
@@ -0,0 +1,1418 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.ofoverlay.impl;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.node.TextNode;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
+import org.onlab.packet.Ip4Address;
+import org.onlab.packet.Ip6Address;
+import org.onlab.packet.IpAddress;
+import org.onlab.packet.TpPort;
+import org.onosproject.cluster.ClusterService;
+import org.onosproject.event.Event;
+import org.onosproject.net.Device;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Port;
+import org.onosproject.net.behaviour.BridgeConfig;
+import org.onosproject.net.behaviour.BridgeDescription;
+import org.onosproject.net.behaviour.BridgeName;
+import org.onosproject.net.behaviour.ControlProtocolVersion;
+import org.onosproject.net.behaviour.ControllerInfo;
+import org.onosproject.net.behaviour.DefaultBridgeDescription;
+import org.onosproject.net.behaviour.DefaultTunnelDescription;
+import org.onosproject.net.behaviour.InterfaceConfig;
+import org.onosproject.net.behaviour.TunnelDescription;
+import org.onosproject.net.behaviour.TunnelEndPoints;
+import org.onosproject.net.behaviour.TunnelKeys;
+import org.onosproject.net.device.DeviceAdminService;
+import org.onosproject.net.device.DeviceEvent;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.driver.Behaviour;
+import org.onosproject.net.driver.DriverHandler;
+import org.onosproject.net.driver.DriverService;
+import org.onosproject.ofoverlay.impl.util.NetworkAddress;
+import org.onosproject.ofoverlay.impl.util.OvsDatapathType;
+import org.onosproject.ofoverlay.impl.util.OvsVersion;
+import org.onosproject.ofoverlay.impl.util.SshUtil;
+import org.onosproject.ovsdb.controller.OvsdbClientService;
+import org.onosproject.ovsdb.controller.OvsdbController;
+import org.onosproject.ovsdb.controller.OvsdbNodeId;
+import org.onosproject.workflow.api.AbstractWorklet;
+import org.onosproject.workflow.api.JsonDataModel;
+import org.onosproject.workflow.api.WorkflowContext;
+import org.onosproject.workflow.api.WorkflowException;
+import org.onosproject.workflow.model.accessinfo.SshAccessInfo;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+import static org.onosproject.net.AnnotationKeys.PORT_NAME;
+import static org.onosproject.workflow.api.CheckCondition.check;
+
+/**
+ * Class for defining OVS workflows.
+ */
+public final class Ovs {
+
+    private static final Logger log = LoggerFactory.getLogger(Ovs.class);
+
+    private static final String MODEL_MGMT_IP = "/mgmtIp";
+    private static final String MODEL_OVSDB_PORT = "/ovsdbPort";
+    private static final String MODEL_OVS_VERSION = "/ovsVersion";
+    private static final String MODEL_OVS_DATAPATH_TYPE = "/ovsDatapathType";
+    private static final String MODEL_SSH_ACCESSINFO = "/sshAccessInfo";
+    private static final String MODEL_OF_DEVID_OVERLAY_BRIDGE = "/ofDevIdBrInt";
+    private static final String MODEL_OF_DEVID_UNDERLAY_BRIDGE = "/ofDevIdBrPhy";
+    private static final String MODEL_OF_DEVID_FOR_OVERLAY_UNDERLAY_BRIDGE = "/ofDevIdBrIntBrPhy";
+    private static final String MODEL_PHY_PORTS = "/physicalPorts";
+    private static final String MODEL_VTEP_IP = "/vtepIp";
+
+    private static final String BRIDGE_OVERLAY = "br-int";
+    private static final String BRIDGE_UNDERLAY = "br-phy";
+
+    private static final int DEVID_IDX_BRIDGE_OVERLAY = 0;
+    private static final int DEVID_IDX_BRIDGE_UNDERLAY_NOVA = 1;
+
+    private static final ControlProtocolVersion BRIDGE_DEFAULT_OF_VERSION = ControlProtocolVersion.OF_1_3;
+    private static final int    OPENFLOW_PORT = 6653;
+    private static final String OPENFLOW_CHANNEL_PROTO = "tcp";
+    private static final String OVSDB_DEVICE_PREFIX = "ovsdb:";
+
+    private static final long TIMEOUT_DEVICE_CREATION_MS = 60000L;
+    private static final long TIMEOUT_PORT_ADDITION_MS = 120000L;
+
+
+    /**
+     * Utility class for OVS workflow.
+     */
+    public static final class OvsUtil {
+
+        private OvsUtil() {
+
+        }
+
+        private static final String OPENFLOW_DEVID_FORMAT = "of:%08x%08x";
+
+        /**
+         * Builds Open-flow device id with ip address, and index.
+         * @param addr ip address
+         * @param index index
+         * @return created device id
+         */
+        public static DeviceId buildOfDeviceId(IpAddress addr, int index) {
+            if (addr.isIp4()) {
+                Ip4Address v4Addr = addr.getIp4Address();
+                return DeviceId.deviceId(String.format(OPENFLOW_DEVID_FORMAT, v4Addr.toInt(), index));
+            } else if (addr.isIp6()) {
+                Ip6Address v6Addr = addr.getIp6Address();
+                return DeviceId.deviceId(String.format(OPENFLOW_DEVID_FORMAT, v6Addr.hashCode(), index));
+            } else {
+                return DeviceId.deviceId(String.format(OPENFLOW_DEVID_FORMAT, addr.hashCode(), index));
+            }
+        }
+
+        /**
+         * Builds OVS data path type.
+         * @param strOvsDatapathType string ovs data path type
+         * @return ovs data path type
+         * @throws WorkflowException workflow exception
+         */
+        public static final OvsDatapathType buildOvsDatapathType(String strOvsDatapathType) throws WorkflowException {
+            try {
+                return OvsDatapathType.valueOf(strOvsDatapathType.toUpperCase());
+            } catch (IllegalArgumentException e) {
+                throw new WorkflowException(e);
+            }
+        }
+
+        /**
+         * Gets OVSDB behavior.
+         * @param context workflow context
+         * @param mgmtIp management ip
+         * @param behaviourClass behavior class
+         * @param <T> behavior class
+         * @return OVSDB behavior
+         * @throws WorkflowException workflow exception
+         */
+        public static final <T extends Behaviour> T getOvsdbBehaviour(WorkflowContext context, String mgmtIp,
+                                                                    Class<T> behaviourClass) throws WorkflowException {
+
+            DriverService driverService = context.getService(DriverService.class);
+
+            DeviceId devId = ovsdbDeviceId(mgmtIp);
+            DriverHandler handler = driverService.createHandler(devId);
+            if (Objects.isNull(handler)) {
+                throw new WorkflowException("Failed to get DriverHandler for " + devId);
+            }
+            T behaviour;
+            try {
+                behaviour =  handler.behaviour(behaviourClass);
+                if (Objects.isNull(behaviour)) {
+                    throw new WorkflowException("Failed to get " + behaviourClass + " for " + devId + "-" + handler);
+                }
+            } catch (IllegalArgumentException e) {
+                throw new WorkflowException("Failed to get " + behaviourClass + " for " + devId + "-" + handler);
+            }
+            return behaviour;
+        }
+
+        /**
+         * Gets bridge description.
+         * @param bridgeConfig bridge config
+         * @param bridgeName bridge name
+         * @return bridge description optional
+         */
+        public static final Optional<BridgeDescription> getBridgeDescription(BridgeConfig bridgeConfig,
+                                                                             String bridgeName) {
+            try {
+                Collection<BridgeDescription> bridges = bridgeConfig.getBridges();
+                for (BridgeDescription br: bridges) {
+                    if (Objects.equals(bridgeName, br.name())) {
+                        return Optional.of(br);
+                    }
+                }
+            } catch (Exception e) {
+                log.error("Exception : ", e);
+            }
+            return Optional.empty();
+        }
+
+        /**
+         * Builds OVSDB device id.
+         * @param mgmtIp management ip address string
+         * @return OVSDB device id
+         */
+        public static final DeviceId ovsdbDeviceId(String mgmtIp) {
+            return DeviceId.deviceId(OVSDB_DEVICE_PREFIX.concat(mgmtIp));
+        }
+
+        /**
+         * Returns {@code true} if this bridge is available;
+         * returns {@code false} otherwise.
+         * @param context workflow context
+         * @param devId device id
+         * @return {@code true} if this bridge is available; {@code false} otherwise.
+         * @throws WorkflowException workflow exception
+         */
+        public static final boolean isAvailableBridge(WorkflowContext context, DeviceId devId)
+                throws WorkflowException {
+
+            if (Objects.isNull(devId)) {
+                throw new WorkflowException("Invalid device id in data model");
+            }
+
+            DeviceService deviceService = context.getService(DeviceService.class);
+            Device dev = deviceService.getDevice(devId);
+            if (Objects.isNull(dev)) {
+                return false;
+            }
+
+            return deviceService.isAvailable(devId);
+        }
+
+        /**
+         * Gets openflow controller information list.
+         * @param context workflow context
+         * @return openflow controller information list
+         * @throws WorkflowException workflow exception
+         */
+        public static final List<ControllerInfo> getOpenflowControllerInfoList(WorkflowContext context)
+                throws WorkflowException {
+            ClusterService clusterService = context.getService(ClusterService.class);
+            java.util.List<org.onosproject.net.behaviour.ControllerInfo> controllers = new ArrayList<>();
+            Sets.newHashSet(clusterService.getNodes()).forEach(
+                    controller -> {
+                        org.onosproject.net.behaviour.ControllerInfo ctrlInfo =
+                                new org.onosproject.net.behaviour.ControllerInfo(controller.ip(),
+                                        OPENFLOW_PORT,
+                                        OPENFLOW_CHANNEL_PROTO);
+                        controllers.add(ctrlInfo);
+                    }
+            );
+            return controllers;
+        }
+
+        /**
+         * Creates bridge.
+         * @param bridgeConfig bridge config
+         * @param name bridge name to create
+         * @param dpid openflow data path id of bridge to create
+         * @param ofControllers openflow controller information list
+         * @param datapathType OVS data path type
+         */
+        public static final void createBridge(BridgeConfig bridgeConfig, String name, String dpid,
+                                              List<ControllerInfo> ofControllers, OvsDatapathType datapathType) {
+            BridgeDescription.Builder bridgeDescBuilder = DefaultBridgeDescription.builder()
+                    .name(name)
+                    .failMode(BridgeDescription.FailMode.SECURE)
+                    .datapathId(dpid)
+                    .disableInBand()
+                    .controlProtocols(Collections.singletonList(BRIDGE_DEFAULT_OF_VERSION))
+                    .controllers(ofControllers);
+
+            if (datapathType != null && !(datapathType.equals(OvsDatapathType.EMPTY))) {
+                bridgeDescBuilder.datapathType(datapathType.toString());
+                log.info("create {} with dataPathType {}", name, datapathType);
+            }
+
+            BridgeDescription bridgeDesc = bridgeDescBuilder.build();
+            bridgeConfig.addBridge(bridgeDesc);
+        }
+
+        /**
+         * Index of data path id in openflow device id.
+         */
+        private static final int DPID_BEGIN_INDEX = 3;
+
+        /**
+         * Gets bridge data path id.
+         * @param devId device id
+         * @return bridge data path id
+         */
+        public static final String bridgeDatapathId(DeviceId devId) {
+            return devId.toString().substring(DPID_BEGIN_INDEX);
+        }
+
+        /**
+         * Gets OVSDB client.
+         * @param context workflow context
+         * @param strMgmtIp management ip address
+         * @param intOvsdbPort OVSDB port
+         * @return ovsdb client
+         * @throws WorkflowException workflow exception
+         */
+        public static final OvsdbClientService getOvsdbClient(
+                WorkflowContext context, String strMgmtIp, int intOvsdbPort) throws WorkflowException {
+            IpAddress mgmtIp = IpAddress.valueOf(strMgmtIp);
+            TpPort ovsdbPort = TpPort.tpPort(intOvsdbPort);
+            OvsdbController ovsdbController = context.getService(OvsdbController.class);
+            return ovsdbController.getOvsdbClient(new OvsdbNodeId(mgmtIp, ovsdbPort.toInt()));
+        }
+
+        /**
+         * Checks whether 2 controller informations include same controller information.
+         * @param a controller information list
+         * @param b controller information list
+         * @return {@code true} if 2 controller informations include same controller information
+         */
+        public static boolean isEqual(List<ControllerInfo> a, List<ControllerInfo> b) {
+            if (a == b) {
+                return true;
+            } else if (a == null) {
+                // equivalent to (a == null && b != null)
+                return false;
+            } else if (b == null) {
+                // equivalent to (a != null && b == null)
+                return false;
+            } else if (a.size() != b.size()) {
+                return false;
+            }
+
+            return a.containsAll(b);
+        }
+
+        /**
+         * Gets the name of the port.
+         * @param port port
+         * @return the name of the port
+         */
+        public static final String portName(Port port) {
+            return port.annotations().value(PORT_NAME);
+        }
+    }
+
+    /**
+     * Work-let class for creating OVSDB device.
+     */
+    public static class CreateOvsdbDevice extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @JsonDataModel(path = MODEL_OVSDB_PORT)
+        Integer intOvsdbPort;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            OvsdbClientService ovsdbClient = OvsUtil.getOvsdbClient(context, strMgmtIp, intOvsdbPort);
+            return ovsdbClient == null || !ovsdbClient.isConnected();
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+            IpAddress mgmtIp = IpAddress.valueOf(strMgmtIp);
+            TpPort ovsdbPort = TpPort.tpPort(intOvsdbPort);
+            OvsdbController ovsdbController = context.getService(OvsdbController.class);
+            context.waitCompletion(DeviceEvent.class, OVSDB_DEVICE_PREFIX.concat(strMgmtIp),
+                    () -> ovsdbController.connect(mgmtIp, ovsdbPort),
+                    TIMEOUT_DEVICE_CREATION_MS
+            );
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+            if (!(event instanceof DeviceEvent)) {
+                return false;
+            }
+            DeviceEvent deviceEvent = (DeviceEvent) event;
+            Device device = deviceEvent.subject();
+            switch (deviceEvent.type()) {
+                case DEVICE_ADDED:
+                case DEVICE_AVAILABILITY_CHANGED:
+                case DEVICE_UPDATED:
+                    return context.getService(DeviceService.class).isAvailable(device.id());
+                default:
+                    return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete the job of worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+    }
+
+
+    /**
+     * Work-let class for removing OVSDB device.
+     */
+    public static class RemoveOvsdbDevice extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            DeviceId devId = DeviceId.deviceId(OVSDB_DEVICE_PREFIX.concat(strMgmtIp));
+
+            Device dev = context.getService(DeviceService.class).getDevice(devId);
+            return dev != null;
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+            IpAddress mgmtIp = IpAddress.valueOf(strMgmtIp);
+            check(mgmtIp != null, "mgmt ip is invalid");
+            DeviceId devId = DeviceId.deviceId(OVSDB_DEVICE_PREFIX.concat(strMgmtIp));
+            DeviceAdminService adminService = context.getService(DeviceAdminService.class);
+
+            context.waitCompletion(DeviceEvent.class, devId.toString(),
+                    () -> adminService.removeDevice(devId),
+                    TIMEOUT_DEVICE_CREATION_MS
+            );
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+            if (!(event instanceof DeviceEvent)) {
+                return false;
+            }
+            DeviceEvent deviceEvent = (DeviceEvent) event;
+            switch (deviceEvent.type()) {
+                case DEVICE_REMOVED:
+                    return !isNext(context);
+                default:
+                    return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+    }
+
+    /**
+     * Work-let class for updating OVS version.
+     */
+    public static class UpdateOvsVersion extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_OVS_VERSION, optional = true)
+        String strOvsVersion;
+
+        @JsonDataModel(path = MODEL_SSH_ACCESSINFO)
+        JsonNode strSshAccessInfo;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            return strOvsVersion == null;
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            SshAccessInfo sshAccessInfo = SshAccessInfo.valueOf(strSshAccessInfo);
+            check(Objects.nonNull(sshAccessInfo), "Invalid ssh access info " + context.data());
+
+            OvsVersion ovsVersion = SshUtil.exec(sshAccessInfo,
+                    session -> SshUtil.fetchOvsVersion(session));
+
+            check(Objects.nonNull(ovsVersion), "Failed to fetch ovs version " + context.data());
+            strOvsVersion = ovsVersion.toString();
+
+            context.completed();
+        }
+    }
+
+    /**
+     * Work-let class for updating overlay bridge device id.
+     */
+    public static class UpdateOverlayBridgeId extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @JsonDataModel(path = MODEL_OF_DEVID_OVERLAY_BRIDGE, optional = true)
+        String strOfDevIdOverlay;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            return strOfDevIdOverlay == null;
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            BridgeConfig bridgeConfig = OvsUtil.getOvsdbBehaviour(context, strMgmtIp, BridgeConfig.class);
+            Optional<BridgeDescription> optBd = OvsUtil.getBridgeDescription(bridgeConfig, BRIDGE_OVERLAY);
+            if (optBd.isPresent()) {
+                Optional<DeviceId> optDevId = optBd.get().deviceId();
+                if (optDevId.isPresent()) {
+                    log.info("Updates {} of device id with existing device id {}", BRIDGE_OVERLAY, optDevId.get());
+                    strOfDevIdOverlay = optDevId.get().toString();
+                } else {
+                    DeviceId newDevId = OvsUtil.buildOfDeviceId(IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_OVERLAY);
+                    log.info("Failed to find devId. Updates {} of device id with new device id {}",
+                            BRIDGE_OVERLAY, newDevId);
+                    strOfDevIdOverlay = newDevId.toString();
+                }
+            } else {
+                DeviceId newDevId = OvsUtil.buildOfDeviceId(IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_OVERLAY);
+                log.info("Failed to find description. Updates {} of device id with new device id {}",
+                        BRIDGE_OVERLAY, newDevId);
+                strOfDevIdOverlay = newDevId.toString();
+            }
+
+            context.completed();
+        }
+    }
+
+    /**
+     * Work-let class for creating overlay openflow bridge.
+     */
+    public static class CreateOverlayBridge extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @JsonDataModel(path = MODEL_OVSDB_PORT)
+        Integer intOvsdbPort;
+
+        @JsonDataModel(path = MODEL_OVS_DATAPATH_TYPE)
+        String strOvsDatapath;
+
+        @JsonDataModel(path = MODEL_OF_DEVID_OVERLAY_BRIDGE, optional = true)
+        String strOfDevIdOverlay;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            check(strOfDevIdOverlay != null, "invalid strOfDevIdOverlay");
+            return !OvsUtil.isAvailableBridge(context, DeviceId.deviceId(strOfDevIdOverlay));
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            check(strOfDevIdOverlay != null, "invalid strOfDevIdOverlay");
+            BridgeConfig bridgeConfig = OvsUtil.getOvsdbBehaviour(context, strMgmtIp, BridgeConfig.class);
+            List<ControllerInfo> ofControllers = OvsUtil.getOpenflowControllerInfoList(context);
+            DeviceId ofDeviceId = DeviceId.deviceId(strOfDevIdOverlay);
+
+            if (ofControllers == null || ofControllers.size() == 0) {
+                throw new WorkflowException("Invalid of controllers");
+            }
+
+            Optional<BridgeDescription> optBd = OvsUtil.getBridgeDescription(bridgeConfig, BRIDGE_OVERLAY);
+            if (!optBd.isPresent()) {
+
+                // If bridge does not exist, just creates a new bridge.
+                context.waitCompletion(DeviceEvent.class, ofDeviceId.toString(),
+                        () -> OvsUtil.createBridge(bridgeConfig,
+                                BRIDGE_OVERLAY,
+                                OvsUtil.bridgeDatapathId(ofDeviceId),
+                                ofControllers,
+                                OvsUtil.buildOvsDatapathType(strOvsDatapath)),
+                        TIMEOUT_DEVICE_CREATION_MS
+                );
+                return;
+
+            } else {
+                BridgeDescription bd = optBd.get();
+                if (OvsUtil.isEqual(ofControllers, bd.controllers())) {
+                    log.error("{} has valid controller setting({})", BRIDGE_OVERLAY, bd.controllers());
+                    context.completed();
+                    return;
+                }
+
+                OvsdbClientService ovsdbClient = OvsUtil.getOvsdbClient(context, strMgmtIp, intOvsdbPort);
+                if (ovsdbClient == null || !ovsdbClient.isConnected()) {
+                    throw new WorkflowException("Invalid ovsdb client for " + strMgmtIp);
+                }
+
+                // If controller settings are not matched, set controller with valid controller information.
+                context.waitCompletion(DeviceEvent.class, ofDeviceId.toString(),
+                        () -> ovsdbClient.setControllersWithDeviceId(bd.deviceId().get(), ofControllers),
+                        TIMEOUT_DEVICE_CREATION_MS
+                );
+                return;
+            }
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+            if (!(event instanceof DeviceEvent)) {
+                return false;
+            }
+            DeviceEvent deviceEvent = (DeviceEvent) event;
+            Device device = deviceEvent.subject();
+            switch (deviceEvent.type()) {
+                case DEVICE_ADDED:
+                case DEVICE_AVAILABILITY_CHANGED:
+                case DEVICE_UPDATED:
+                    return context.getService(DeviceService.class).isAvailable(device.id());
+                default:
+                    return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete the job of worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+    }
+
+    /**
+     * Work-let class for creating overlay openflow bridge.
+     */
+    public static class CreateOverlayBridgeMultiEvent extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @JsonDataModel(path = MODEL_OVSDB_PORT)
+        Integer intOvsdbPort;
+
+        @JsonDataModel(path = MODEL_OVS_DATAPATH_TYPE)
+        String strOvsDatapath;
+
+        @JsonDataModel(path = MODEL_OF_DEVID_OVERLAY_BRIDGE, optional = true)
+        String strOfDevIdOverlay;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            check(strOfDevIdOverlay != null, "invalid strOfDevIdOverlay");
+            return !OvsUtil.isAvailableBridge(context, DeviceId.deviceId(strOfDevIdOverlay));
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            check(strOfDevIdOverlay != null, "invalid strOfDevIdOverlay");
+            BridgeConfig bridgeConfig = OvsUtil.getOvsdbBehaviour(context, strMgmtIp, BridgeConfig.class);
+            List<ControllerInfo> ofControllers = OvsUtil.getOpenflowControllerInfoList(context);
+            DeviceId ofDeviceId = DeviceId.deviceId(strOfDevIdOverlay);
+
+            if (ofControllers == null || ofControllers.size() == 0) {
+                throw new WorkflowException("Invalid of controllers");
+            }
+
+            Optional<BridgeDescription> optBd = OvsUtil.getBridgeDescription(bridgeConfig, BRIDGE_OVERLAY);
+            if (!optBd.isPresent()) {
+
+                Set<String> eventHints = Sets.newHashSet(ofDeviceId.toString());
+
+                context.waitAnyCompletion(DeviceEvent.class, eventHints,
+                        () -> OvsUtil.createBridge(bridgeConfig,
+                                                   BRIDGE_OVERLAY,
+                                                   OvsUtil.bridgeDatapathId(ofDeviceId),
+                                                   ofControllers,
+                                                   OvsUtil.buildOvsDatapathType(strOvsDatapath)),
+                        TIMEOUT_DEVICE_CREATION_MS
+                );
+                return;
+
+            } else {
+                BridgeDescription bd = optBd.get();
+                if (OvsUtil.isEqual(ofControllers, bd.controllers())) {
+                    log.error("{} has valid controller setting({})", BRIDGE_OVERLAY, bd.controllers());
+                    context.completed();
+                    return;
+                }
+
+                OvsdbClientService ovsdbClient = OvsUtil.getOvsdbClient(context, strMgmtIp, intOvsdbPort);
+                if (ovsdbClient == null || !ovsdbClient.isConnected()) {
+                    throw new WorkflowException("Invalid ovsdb client for " + strMgmtIp);
+                }
+
+                // If controller settings are not matched, set controller with valid controller information.
+                Set<String> eventHints = Sets.newHashSet(ofDeviceId.toString());
+
+                context.waitAnyCompletion(DeviceEvent.class, eventHints,
+                                       () -> ovsdbClient.setControllersWithDeviceId(bd.deviceId().get(), ofControllers),
+                                       TIMEOUT_DEVICE_CREATION_MS
+                );
+                return;
+            }
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+            if (!(event instanceof DeviceEvent)) {
+                return false;
+            }
+            DeviceEvent deviceEvent = (DeviceEvent) event;
+            Device device = deviceEvent.subject();
+            switch (deviceEvent.type()) {
+                case DEVICE_ADDED:
+                case DEVICE_AVAILABILITY_CHANGED:
+                case DEVICE_UPDATED:
+                    return context.getService(DeviceService.class).isAvailable(device.id());
+                default:
+                    return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete the job of worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+    }
+
+    /**
+     * Work-let class for updating underlay bridge device id.
+     */
+    public static class UpdateUnderlayBridgeId extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @JsonDataModel(path = MODEL_OF_DEVID_UNDERLAY_BRIDGE, optional = true)
+        String strOfDevIdUnderlay;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            return strOfDevIdUnderlay == null;
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            BridgeConfig bridgeConfig = OvsUtil.getOvsdbBehaviour(context, strMgmtIp, BridgeConfig.class);
+            Optional<BridgeDescription> optBd = OvsUtil.getBridgeDescription(bridgeConfig, BRIDGE_UNDERLAY);
+            if (optBd.isPresent()) {
+                Optional<DeviceId> optDevId = optBd.get().deviceId();
+                if (optDevId.isPresent()) {
+                    log.info("Updates {} of device id with existing device id {}", BRIDGE_UNDERLAY, optDevId.get());
+                    strOfDevIdUnderlay = optDevId.get().toString();
+                } else {
+                    DeviceId devId = OvsUtil.buildOfDeviceId(IpAddress.valueOf(strMgmtIp),
+                            DEVID_IDX_BRIDGE_UNDERLAY_NOVA);
+                    log.info("Failed to find devId. Updates {} of device id with new device id {}",
+                            BRIDGE_UNDERLAY, devId);
+                    strOfDevIdUnderlay = devId.toString();
+                }
+            } else {
+                DeviceId devId = OvsUtil.buildOfDeviceId(IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_UNDERLAY_NOVA);
+                log.info("Failed to find description. Updates {} of device id with new device id {}",
+                        BRIDGE_UNDERLAY, devId);
+                strOfDevIdUnderlay = devId.toString();
+            }
+
+            context.completed();
+        }
+    }
+
+    /**
+     * Work-let class for creating underlay openflow bridge.
+     */
+    public static class CreateUnderlayBridge extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @JsonDataModel(path = MODEL_OVSDB_PORT)
+        Integer intOvsdbPort;
+
+        @JsonDataModel(path = MODEL_OVS_DATAPATH_TYPE)
+        String strOvsDatapath;
+
+        @JsonDataModel(path = MODEL_OF_DEVID_UNDERLAY_BRIDGE, optional = true)
+        String strOfDevIdUnderlay;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            check(strOfDevIdUnderlay != null, "invalid strOfDevIdUnderlay");
+            return !OvsUtil.isAvailableBridge(context, DeviceId.deviceId(strOfDevIdUnderlay));
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            check(strOfDevIdUnderlay != null, "invalid strOfDevIdUnderlay");
+            BridgeConfig bridgeConfig = OvsUtil.getOvsdbBehaviour(context, strMgmtIp, BridgeConfig.class);
+            List<ControllerInfo> ofControllers = OvsUtil.getOpenflowControllerInfoList(context);
+            DeviceId ofDeviceId = DeviceId.deviceId(strOfDevIdUnderlay);
+
+            if (ofControllers == null || ofControllers.size() == 0) {
+                throw new WorkflowException("Invalid of controllers");
+            }
+
+            Optional<BridgeDescription> optBd = OvsUtil.getBridgeDescription(bridgeConfig, BRIDGE_UNDERLAY);
+            if (!optBd.isPresent()) {
+
+                // If bridge does not exist, just creates a new bridge.
+                context.waitCompletion(DeviceEvent.class, ofDeviceId.toString(),
+                        () -> OvsUtil.createBridge(bridgeConfig,
+                                BRIDGE_UNDERLAY,
+                                OvsUtil.bridgeDatapathId(ofDeviceId),
+                                ofControllers,
+                                OvsUtil.buildOvsDatapathType(strOvsDatapath)),
+                        TIMEOUT_DEVICE_CREATION_MS
+                );
+                return;
+
+            } else {
+                BridgeDescription bd = optBd.get();
+                if (OvsUtil.isEqual(ofControllers, bd.controllers())) {
+                    log.error("{} has valid controller setting({})", BRIDGE_UNDERLAY, bd.controllers());
+                    context.completed();
+                    return;
+                }
+
+                OvsdbClientService ovsdbClient = OvsUtil.getOvsdbClient(context, strMgmtIp, intOvsdbPort);
+                if (ovsdbClient == null || !ovsdbClient.isConnected()) {
+                    throw new WorkflowException("Invalid ovsdb client for " + strMgmtIp);
+                }
+
+                // If controller settings are not matched, set controller with valid controller information.
+                context.waitCompletion(DeviceEvent.class, ofDeviceId.toString(),
+                        () -> ovsdbClient.setControllersWithDeviceId(bd.deviceId().get(), ofControllers),
+                        TIMEOUT_DEVICE_CREATION_MS
+                );
+                return;
+            }
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+            if (!(event instanceof DeviceEvent)) {
+                return false;
+            }
+            DeviceEvent deviceEvent = (DeviceEvent) event;
+            Device device = deviceEvent.subject();
+            switch (deviceEvent.type()) {
+                case DEVICE_ADDED:
+                case DEVICE_AVAILABILITY_CHANGED:
+                case DEVICE_UPDATED:
+                    return context.getService(DeviceService.class).isAvailable(device.id());
+                default:
+                    return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete the job of worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+
+    }
+
+    /**
+     * Work-let class for creating vxlan port on the overlay bridge.
+     */
+    public static class CreateOverlayBridgeVxlanPort extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @JsonDataModel(path = MODEL_OF_DEVID_OVERLAY_BRIDGE, optional = true)
+        String strOfDevIdOverlay;
+
+        private static final String OVS_VXLAN_PORTNAME = "vxlan";
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            check(strOfDevIdOverlay != null, "invalid strOfDevIdOverlay");
+            DeviceId deviceId = DeviceId.deviceId(strOfDevIdOverlay);
+            if (Objects.isNull(deviceId)) {
+                throw new WorkflowException("Invalid br-int bridge, before creating VXLAN port");
+            }
+
+            DeviceService deviceService = context.getService(DeviceService.class);
+            return !deviceService.getPorts(deviceId)
+                    .stream()
+                    .filter(port -> OvsUtil.portName(port).contains(OVS_VXLAN_PORTNAME) && port.isEnabled())
+                    .findAny().isPresent();
+        }
+
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            check(strOfDevIdOverlay != null, "invalid strOfDevIdOverlay");
+            TunnelDescription description = DefaultTunnelDescription.builder()
+                    .deviceId(BRIDGE_OVERLAY)
+                    .ifaceName(OVS_VXLAN_PORTNAME)
+                    .type(TunnelDescription.Type.VXLAN)
+                    .remote(TunnelEndPoints.flowTunnelEndpoint())
+                    .key(TunnelKeys.flowTunnelKey())
+                    .build();
+
+            DeviceId ofDeviceId = DeviceId.deviceId(strOfDevIdOverlay);
+            InterfaceConfig interfaceConfig = OvsUtil.getOvsdbBehaviour(context, strMgmtIp, InterfaceConfig.class);
+
+            context.waitCompletion(DeviceEvent.class, ofDeviceId.toString(),
+                    () -> interfaceConfig.addTunnelMode(BRIDGE_OVERLAY, description),
+                    TIMEOUT_DEVICE_CREATION_MS
+            );
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+            if (!(event instanceof DeviceEvent)) {
+                return false;
+            }
+            DeviceEvent deviceEvent = (DeviceEvent) event;
+            switch (deviceEvent.type()) {
+                case PORT_ADDED:
+                    return !isNext(context);
+                default:
+                    return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete the job of worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+    }
+
+    /**
+     * Work-let class for adding physical ports on the underlay openflow bridge.
+     */
+    public static class AddPhysicalPortsOnUnderlayBridge extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @JsonDataModel(path = MODEL_OVSDB_PORT)
+        Integer intOvsdbPort;
+
+        @JsonDataModel(path = MODEL_OF_DEVID_UNDERLAY_BRIDGE, optional = true)
+        String strOfDevIdUnderlay;
+
+        @JsonDataModel(path = MODEL_OVS_DATAPATH_TYPE)
+        String strOvsDatapath;
+
+        @JsonDataModel(path = MODEL_PHY_PORTS)
+        ArrayNode arrNodePhysicalPorts;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+            check(strOfDevIdUnderlay != null, "invalid strOfDevIdUnderlay");
+            DeviceId brphyDevId = DeviceId.deviceId(strOfDevIdUnderlay);
+            return !hasAllPhysicalPorts(context, brphyDevId);
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+            check(strOfDevIdUnderlay != null, "invalid strOfDevIdUnderlay");
+            DeviceId brphyDevId = DeviceId.deviceId(strOfDevIdUnderlay);
+
+            context.waitCompletion(DeviceEvent.class, brphyDevId.toString(),
+                    () -> addPhysicalPorts(context, brphyDevId, BRIDGE_UNDERLAY, strOvsDatapath),
+                    TIMEOUT_PORT_ADDITION_MS
+            );
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+            if (!(event instanceof DeviceEvent)) {
+                return false;
+            }
+            DeviceEvent deviceEvent = (DeviceEvent) event;
+            switch (deviceEvent.type()) {
+                case PORT_ADDED:
+                    return !isNext(context);
+                default:
+                    return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete the job of worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+
+        private final List<String> getPhysicalPorts(WorkflowContext context) throws WorkflowException {
+            List<String> ports = Lists.newArrayList();
+            for (JsonNode jsonNode : arrNodePhysicalPorts) {
+                check(jsonNode instanceof TextNode, "Invalid physical ports " + arrNodePhysicalPorts);
+                ports.add(jsonNode.asText());
+            }
+            return ports;
+        }
+
+        private final boolean hasAllPhysicalPorts(WorkflowContext context, DeviceId devId) throws WorkflowException {
+
+            List<Port> devPorts = context.getService(DeviceService.class).getPorts(devId);
+            check(devPorts != null, "Invalid device ports for " + devId);
+            List<String> physicalPorts = getPhysicalPorts(context);
+            check(physicalPorts != null, "Invalid physical ports" + context);
+
+            log.info("physicalPorts: {} for {}", physicalPorts, devId);
+            for (String port: physicalPorts) {
+                if (devPorts.stream().noneMatch(p -> OvsUtil.portName(p).contains(port))) {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        private final boolean hasPort(WorkflowContext context, DeviceId devId, String portName)
+                throws WorkflowException {
+
+            List<Port> devPorts = context.getService(DeviceService.class).getPorts(devId);
+            check(devPorts != null, "Invalid device ports for " + devId);
+            return devPorts.stream().anyMatch(p -> OvsUtil.portName(p).contains(portName));
+        }
+
+        private final void addPhysicalPorts(WorkflowContext context, DeviceId devId, String bridgeName,
+                                            String strOvsDatapathType)
+                throws WorkflowException {
+            OvsdbClientService ovsdbClient = OvsUtil.getOvsdbClient(context, strMgmtIp, intOvsdbPort);
+            check(ovsdbClient != null, "Invalid ovsdb client");
+
+            List<String> physicalPorts = getPhysicalPorts(context);
+            check(physicalPorts != null, "Invalid physical ports");
+
+            OvsDatapathType datapathType = OvsUtil.buildOvsDatapathType(strOvsDatapathType);
+            check(datapathType != null, "Invalid data path type");
+
+            List<String> sortedPhyPorts = physicalPorts.stream().sorted().collect(Collectors.toList());
+
+            for (String port: sortedPhyPorts) {
+                if (hasPort(context, devId, port)) {
+                    continue;
+                }
+                log.info("adding port {} on {}", port, devId);
+                switch (datapathType) {
+                    case NETDEV:
+                        throw new WorkflowException("NETDEV datapathType are not supported");
+                        //break;
+                    case SYSTEM:
+                    default:
+                        ovsdbClient.createPort(BridgeName.bridgeName(bridgeName).name(), port);
+                }
+            }
+        }
+    }
+
+    /**
+     * Work-let class for configure local ip of underlay openflow bridge.
+     */
+    public static class ConfigureUnderlayBridgeLocalIp extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_SSH_ACCESSINFO)
+        JsonNode strSshAccessInfo;
+
+        @JsonDataModel(path = MODEL_VTEP_IP)
+        String strVtepIp;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            SshAccessInfo sshAccessInfo = SshAccessInfo.valueOf(strSshAccessInfo);
+            check(Objects.nonNull(sshAccessInfo), "Invalid ssh access info " + context.data());
+
+            NetworkAddress vtepIp = NetworkAddress.valueOf(strVtepIp);
+            check(Objects.nonNull(vtepIp), "Invalid vtep ip " + context.data());
+
+            return !SshUtil.exec(sshAccessInfo,
+                    session ->
+                            SshUtil.hasIpAddrOnInterface(session, BRIDGE_UNDERLAY, vtepIp)
+                                    && SshUtil.isIpLinkUpOnInterface(session, BRIDGE_UNDERLAY)
+            );
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            SshAccessInfo sshAccessInfo = SshAccessInfo.valueOf(strSshAccessInfo);
+            check(Objects.nonNull(sshAccessInfo), "Invalid ssh access info " + context.data());
+
+            NetworkAddress vtepIp = NetworkAddress.valueOf(strVtepIp);
+            check(Objects.nonNull(vtepIp), "Invalid vtep ip " + context.data());
+
+            SshUtil.exec(sshAccessInfo,
+                    session -> {
+                        SshUtil.addIpAddrOnInterface(session, BRIDGE_UNDERLAY, vtepIp);
+                        SshUtil.setIpLinkUpOnInterface(session, BRIDGE_UNDERLAY);
+                        return "";
+                    });
+
+            context.completed();
+        }
+    }
+
+    /**
+     * Work-let class for deleting overlay bridge config.
+     */
+    public static class DeleteOverlayBridgeConfig extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            BridgeConfig bridgeConfig = OvsUtil.getOvsdbBehaviour(context, strMgmtIp, BridgeConfig.class);
+
+            Collection<BridgeDescription> bridges = bridgeConfig.getBridges();
+            return bridges.stream()
+                    .anyMatch(bd -> Objects.equals(bd.name(), BRIDGE_OVERLAY));
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            BridgeConfig bridgeConfig = OvsUtil.getOvsdbBehaviour(context, strMgmtIp, BridgeConfig.class);
+
+            bridgeConfig.deleteBridge(BridgeName.bridgeName(BRIDGE_OVERLAY));
+
+            for (int i = 0; i < 10; i++) {
+                if (!isNext(context)) {
+                    context.completed();
+                    return;
+                }
+                sleep(50);
+            }
+            throw new WorkflowException("Timeout happened for removing config");
+        }
+
+        protected void sleep(long ms) {
+            try {
+                Thread.sleep(ms);
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    /**
+     * Work-let class for removing overlay bridge openflow device.
+     */
+    public static class RemoveOverlayBridgeOfDevice extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            DeviceId devId = OvsUtil.buildOfDeviceId(IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_OVERLAY);
+
+            Device dev = context.getService(DeviceService.class).getDevice(devId);
+            return dev != null;
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            DeviceId devId = OvsUtil.buildOfDeviceId(IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_OVERLAY);
+
+            DeviceAdminService adminService = context.getService(DeviceAdminService.class);
+
+            context.waitCompletion(DeviceEvent.class, devId.toString(),
+                    () -> adminService.removeDevice(devId),
+                    TIMEOUT_DEVICE_CREATION_MS
+            );
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+            if (!(event instanceof DeviceEvent)) {
+                return false;
+            }
+            DeviceEvent deviceEvent = (DeviceEvent) event;
+            switch (deviceEvent.type()) {
+                case DEVICE_REMOVED:
+                    return !isNext(context);
+                default:
+                    return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete the job of worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+    }
+
+    /**
+     * Work-let class for deleting underlay bridge config.
+     */
+    public static class DeleteUnderlayBridgeConfig extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            BridgeConfig bridgeConfig = OvsUtil.getOvsdbBehaviour(context, strMgmtIp, BridgeConfig.class);
+
+            Collection<BridgeDescription> bridges = bridgeConfig.getBridges();
+            return bridges.stream()
+                    .anyMatch(bd -> Objects.equals(bd.name(), BRIDGE_UNDERLAY));
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            BridgeConfig bridgeConfig = OvsUtil.getOvsdbBehaviour(context, strMgmtIp, BridgeConfig.class);
+
+            bridgeConfig.deleteBridge(BridgeName.bridgeName(BRIDGE_UNDERLAY));
+
+            for (int i = 0; i < 10; i++) {
+                if (!isNext(context)) {
+                    context.completed();
+                    return;
+                }
+                sleep(50);
+            }
+            throw new WorkflowException("Timeout happened for removing config");
+        }
+
+        protected void sleep(long ms) {
+            try {
+                Thread.sleep(ms);
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    /**
+     * Work-let class for removing underlay bridge openflow device.
+     */
+    public static class RemoveUnderlayBridgeOfDevice extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            DeviceId devId = OvsUtil.buildOfDeviceId(IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_UNDERLAY_NOVA);
+
+            Device dev = context.getService(DeviceService.class).getDevice(devId);
+            return dev != null;
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            DeviceId devId = OvsUtil.buildOfDeviceId(IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_UNDERLAY_NOVA);
+
+            DeviceAdminService adminService = context.getService(DeviceAdminService.class);
+
+            context.waitCompletion(DeviceEvent.class, devId.toString(),
+                    () -> adminService.removeDevice(devId),
+                    TIMEOUT_DEVICE_CREATION_MS
+            );
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+            if (!(event instanceof DeviceEvent)) {
+                return false;
+            }
+            DeviceEvent deviceEvent = (DeviceEvent) event;
+            switch (deviceEvent.type()) {
+                case DEVICE_REMOVED:
+                    return !isNext(context);
+                default:
+                    return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete the job of worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+    }
+
+    /**
+     * Work-let class for removing underlay bridge and overlay openflow device.
+     */
+    public static class RemoveBridgeOfDevice extends AbstractWorklet {
+
+        @JsonDataModel(path = MODEL_MGMT_IP)
+        String strMgmtIp;
+
+        @JsonDataModel(path = MODEL_OF_DEVID_FOR_OVERLAY_UNDERLAY_BRIDGE, optional = true)
+        ObjectNode ofDevId;
+
+        @Override
+        public boolean isNext(WorkflowContext context) throws WorkflowException {
+
+            boolean isOfDevicePresent = true;
+
+            if (ofDevId == null) {
+                ofDevId = JsonNodeFactory.instance.objectNode();
+                ofDevId.put(String.valueOf(DEVID_IDX_BRIDGE_OVERLAY), OvsUtil.buildOfDeviceId(
+                        IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_OVERLAY).toString());
+                ofDevId.put(String.valueOf(DEVID_IDX_BRIDGE_UNDERLAY_NOVA), OvsUtil.buildOfDeviceId(
+                        IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_UNDERLAY_NOVA).toString());
+            }
+
+            if (context.getService(DeviceService.class).
+                    getDevice(DeviceId.deviceId(
+                            ofDevId.get(String.valueOf(DEVID_IDX_BRIDGE_OVERLAY)).asText())) == null) {
+                isOfDevicePresent = false;
+            }
+            if (context.getService(DeviceService.class).
+                    getDevice(DeviceId.deviceId(
+                            ofDevId.get(String.valueOf(DEVID_IDX_BRIDGE_UNDERLAY_NOVA)).asText())) == null) {
+                isOfDevicePresent = false;
+            }
+
+            return isOfDevicePresent;
+        }
+
+        @Override
+        public void process(WorkflowContext context) throws WorkflowException {
+
+            DeviceAdminService adminService = context.getService(DeviceAdminService.class);
+            String ofDevIdOverlay;
+            String ofDevIdUnderlay;
+
+            if (ofDevId == null) {
+                ofDevId = JsonNodeFactory.instance.objectNode();
+                ofDevId.put(String.valueOf(DEVID_IDX_BRIDGE_OVERLAY), OvsUtil.buildOfDeviceId(
+                        IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_OVERLAY).toString());
+                ofDevId.put(String.valueOf(DEVID_IDX_BRIDGE_UNDERLAY_NOVA), OvsUtil.buildOfDeviceId(
+                        IpAddress.valueOf(strMgmtIp), DEVID_IDX_BRIDGE_UNDERLAY_NOVA).toString());
+            }
+
+            ofDevIdOverlay = ofDevId.get(String.valueOf(DEVID_IDX_BRIDGE_OVERLAY)).asText();
+            ofDevIdUnderlay = ofDevId.get(String.valueOf(DEVID_IDX_BRIDGE_UNDERLAY_NOVA)).asText();
+
+            Set<String> eventHints = Sets.newHashSet(ofDevIdOverlay, ofDevIdUnderlay);
+
+            context.waitAnyCompletion(DeviceEvent.class, eventHints,
+                                      () -> {
+                                                adminService.removeDevice(DeviceId.deviceId(ofDevIdOverlay));
+                                                adminService.removeDevice(DeviceId.deviceId(ofDevIdUnderlay));
+                                            },
+                                   TIMEOUT_DEVICE_CREATION_MS
+            );
+        }
+
+        @Override
+        public boolean isCompleted(WorkflowContext context, Event event)throws WorkflowException {
+            if (!(event instanceof DeviceEvent)) {
+                return false;
+            }
+            DeviceEvent deviceEvent = (DeviceEvent) event;
+            switch (deviceEvent.type()) {
+                case DEVICE_REMOVED:
+                    log.trace("GOT DEVICE REMOVED EVENT FOR DEVICE {}", event.subject());
+                    return !isNext(context);
+                default:
+                    return false;
+            }
+        }
+
+        @Override
+        public void timeout(WorkflowContext context) throws WorkflowException {
+            if (!isNext(context)) {
+                context.completed(); //Complete the job of worklet by timeout
+            } else {
+                super.timeout(context);
+            }
+        }
+    }
+}
diff --git a/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/package-info.java b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/package-info.java
new file mode 100644
index 0000000..42214bc
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Open-flow overlay implementation package.
+ */
+package org.onosproject.ofoverlay.impl;
diff --git a/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/NetworkAddress.java b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/NetworkAddress.java
new file mode 100644
index 0000000..c8a8829
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/NetworkAddress.java
@@ -0,0 +1,112 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.ofoverlay.impl.util;
+
+import com.google.common.base.MoreObjects;
+import org.onlab.packet.IpAddress;
+import org.onlab.packet.IpPrefix;
+
+import java.util.Objects;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+/**
+ * Representation of a network address, which consists of IP address and prefix.
+ */
+public final class NetworkAddress {
+    private final IpAddress ip;
+    private final IpPrefix prefix;
+
+    /**
+     * Constructor for a given IP address and prefix.
+     *
+     * @param ip ip address
+     * @param prefix ip prefix
+     */
+    private NetworkAddress(IpAddress ip, IpPrefix prefix) {
+        this.ip = ip;
+        this.prefix = prefix;
+    }
+
+    /**
+     * Converts a CIDR notation string into a network address.
+     *
+     * @param cidr cidr
+     * @return network address
+     * @throws IllegalArgumentException if the cidr is not valid
+     */
+    public static NetworkAddress valueOf(String cidr) {
+        checkArgument(cidr.contains("/"));
+
+        IpAddress ipAddress = IpAddress.valueOf(cidr.split("/")[0]);
+        IpPrefix ipPrefix = IpPrefix.valueOf(cidr);
+
+        return new NetworkAddress(ipAddress, ipPrefix);
+    }
+
+    /**
+     * Returns the IP address value of the network address.
+     *
+     * @return ip address
+     */
+    public IpAddress ip() {
+        return this.ip;
+    }
+
+    /**
+     * Returns the IP prefix value of the network address.
+     *
+     * @return ip prefix
+     */
+    public IpPrefix prefix() {
+        return this.prefix;
+    }
+
+    /**
+     * Converts a network address to a CIDR notation.
+     *
+     * @return cidr notation string
+     */
+    public String cidr() {
+        return ip.toString() + "/" + prefix.prefixLength();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj instanceof NetworkAddress) {
+            NetworkAddress that = (NetworkAddress) obj;
+            return Objects.equals(ip, that.ip) && Objects.equals(prefix, that.prefix);
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(ip, prefix);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("IpAddress", ip)
+                .add("IpPrefix", prefix)
+                .toString();
+    }
+}
\ No newline at end of file
diff --git a/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/OvsDatapathType.java b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/OvsDatapathType.java
new file mode 100644
index 0000000..0a64e93
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/OvsDatapathType.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.ofoverlay.impl.util;
+
+/**
+ * Enumeration for OVS data path type.
+ */
+public enum OvsDatapathType {
+    EMPTY(""),
+    NETDEV("netdev"),
+    SYSTEM("system");
+
+    private final String value;
+
+    /**
+     * Constructor for OvsDatapathType enumeration.
+     *
+     * @param value string OvsDatapathType
+     */
+    OvsDatapathType(String value) {
+        this.value = value;
+    }
+
+    @Override
+    public String toString() {
+        return value;
+    }
+}
diff --git a/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/OvsVersion.java b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/OvsVersion.java
new file mode 100644
index 0000000..015ac73
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/OvsVersion.java
@@ -0,0 +1,154 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.ofoverlay.impl.util;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Class for OVS Version.
+ */
+public final class OvsVersion {
+    protected static final Logger log = LoggerFactory.getLogger(OvsVersion.class);
+
+    private int[] versionElements = new int[] {0, 0, 0, Integer.MAX_VALUE};
+    private int depth = 0;
+
+    /**
+     * Constructor for OvsVersion.
+     * @param ovsVerStr OVS version string
+     */
+    private OvsVersion(String ovsVerStr) {
+
+        // Supporting
+        // 1.2.3 (depth = 3, public release)
+        // 1.2.3.4 (depth = 4, beta release)
+        Matcher m = Pattern.compile("(\\d+)\\.(\\d+)\\.(\\d+)(\\.(\\d+))?").matcher(ovsVerStr);
+
+        if (!m.matches()) {
+            throw new IllegalArgumentException("Malformed OVS version");
+        }
+
+        versionElements[0] = Integer.parseInt(m.group(1));
+        versionElements[1] = Integer.parseInt(m.group(2));
+        versionElements[2] = Integer.parseInt(m.group(3));
+
+        if (m.group(4) == null) {
+            depth = 3;
+            return;
+        }
+
+        versionElements[3] = Integer.parseInt(m.group(5));
+        depth = 4;
+    }
+
+    /**
+     * Builder for OvsVersion.
+     * @param ovsVersionStr OVS version string
+     * @return ovs version
+     */
+    public static OvsVersion build(String ovsVersionStr) {
+        try {
+            return new OvsVersion(ovsVersionStr);
+        } catch (IllegalArgumentException e) {
+            log.error("Exception Occurred {}", e);
+            return null;
+        }
+    }
+
+    private int get(int level) {
+        return versionElements[level];
+    }
+
+    private int compare(OvsVersion tgt) {
+        //Comparison example
+        // 2.7.0 < 2.7.2
+        // 2.7.0 > 2.6.9.12
+        // 2.7.0 > 2.7.0.0 (because 2.7.0 is public release)
+        for (int i = 0; i < versionElements.length; i++) {
+            if (versionElements[i] == tgt.get(i)) {
+                continue;
+            } else if (versionElements[i] < tgt.get(i)) {
+                return (i + 1) * -1;
+            } else {
+                return (i + 1);
+            }
+        }
+        return 0;
+    }
+
+    /**
+     * Returns whether this OVS version is equal to the target OVS version.
+     * @param tgt taret OVS version
+     * @return whether this OVS version is equal to the target OVS version
+     */
+    public boolean isEqOf(OvsVersion tgt) {
+        return (compare(tgt) == 0);
+    }
+
+    /**
+     * Returns whether this OVS version is prior to the target OVS version.
+     * @param tgt taret OVS version
+     * @return whether this OVS version is prior to the target OVS version
+     */
+    public boolean isPriorOf(OvsVersion tgt) {
+        return (compare(tgt) < 0);
+    }
+
+    /**
+     * Returns whether this OVS version is prior or equal to the target OVS version.
+     * @param tgt taret OVS version
+     * @return whether this OVS version is prior or equal to the target OVS version
+     */
+    public boolean isPriorOrEqOf(OvsVersion tgt) {
+        return (compare(tgt) <= 0);
+    }
+
+    /**
+     * Returns whether this OVS version is later to the target OVS version.
+     * @param tgt taret OVS version
+     * @return whether this OVS version is later to the target OVS version
+     */
+    public boolean isLaterOf(OvsVersion tgt) {
+        return (compare(tgt) > 0);
+    }
+
+    /**
+     * Returns whether this OVS version is later or equal to the target OVS version.
+     * @param tgt taret OVS version
+     * @return whether this OVS version is later or equal to the target OVS version
+     */
+    public boolean isLaterOrEqOf(OvsVersion tgt) {
+        return (compare(tgt) >= 0);
+    }
+
+    @Override
+    public String toString() {
+
+        StringBuilder strbuild = new StringBuilder();
+        strbuild.append(versionElements[0]);
+
+        for (int i = 1; i < depth; i++) {
+            strbuild.append(".");
+            strbuild.append(versionElements[i]);
+        }
+        return strbuild.toString();
+    }
+
+}
\ No newline at end of file
diff --git a/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/SshBehavior.java b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/SshBehavior.java
new file mode 100644
index 0000000..6189837
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/SshBehavior.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.ofoverlay.impl.util;
+
+import com.jcraft.jsch.Session;
+import org.onosproject.workflow.api.WorkflowException;
+
+/**
+ * Functional interface for ssh behavior.
+ * @param <R> return value of ssh behavior
+ */
+@FunctionalInterface
+public interface SshBehavior<R> {
+
+    R apply(Session session) throws WorkflowException;
+
+}
diff --git a/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/SshUtil.java b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/SshUtil.java
new file mode 100644
index 0000000..0c6caff
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/SshUtil.java
@@ -0,0 +1,366 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.ofoverlay.impl.util;
+
+import com.google.common.io.CharStreams;
+import com.jcraft.jsch.Channel;
+import com.jcraft.jsch.ChannelExec;
+import com.jcraft.jsch.JSch;
+import com.jcraft.jsch.JSchException;
+import com.jcraft.jsch.Session;
+import org.onlab.packet.IpAddress;
+import org.onosproject.workflow.api.WorkflowException;
+import org.onosproject.workflow.model.accessinfo.SshAccessInfo;
+import org.slf4j.Logger;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.util.Collections;
+import java.util.Set;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+
+import static org.onosproject.workflow.api.CheckCondition.check;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Class for SSH utilities.
+ */
+public final class SshUtil {
+
+    protected static final Logger log = getLogger(SshUtil.class);
+
+    private static final String STRICT_HOST_CHECKING = "StrictHostKeyChecking";
+    private static final String DEFAULT_STRICT_HOST_CHECKING = "no";
+    private static final int DEFAULT_SESSION_TIMEOUT = 30000; // milliseconds
+
+    private static final String SPACESEPERATOR = " ";
+
+    /**
+     * Default constructor.
+     */
+    private SshUtil() {
+    }
+
+    /**
+     * Creates a new session with a given ssh access information.
+     *
+     * @param sshInfo information to ssh to the remote server
+     * @return ssh session, or null
+     */
+    public static Session connect(SshAccessInfo sshInfo) {
+        Session session;
+
+        try {
+            JSch jsch = new JSch();
+            jsch.addIdentity(sshInfo.privateKey());
+
+            session = jsch.getSession(sshInfo.user(),
+                    sshInfo.remoteIp().toString(),
+                    sshInfo.port().toInt());
+            session.setConfig(STRICT_HOST_CHECKING, DEFAULT_STRICT_HOST_CHECKING);
+            session.connect(DEFAULT_SESSION_TIMEOUT);
+
+        } catch (JSchException e) {
+            log.warn("Failed to connect to {}", sshInfo.toString(), e);
+            session = authUserPwd(sshInfo);
+        }
+        return session;
+    }
+
+    /**
+     * Creates a new session with ssh access info.
+     *
+     * @param sshInfo information to ssh to the remote server
+     * @return ssh session, or null
+     */
+    public static Session authUserPwd(SshAccessInfo sshInfo) {
+        log.info("Retrying Session with {}", sshInfo);
+        try {
+            JSch jsch = new JSch();
+
+            Session session = jsch.getSession(sshInfo.user(),
+                    sshInfo.remoteIp().toString(),
+                    sshInfo.port().toInt());
+            session.setPassword(sshInfo.password());
+            session.setConfig(STRICT_HOST_CHECKING, DEFAULT_STRICT_HOST_CHECKING);
+            session.connect(DEFAULT_SESSION_TIMEOUT);
+
+            return session;
+        } catch (JSchException e) {
+            log.warn("Failed to connect to {} due to {}", sshInfo.toString(), e);
+            return null;
+        }
+    }
+
+    /**
+     * Closes a connection.
+     *
+     * @param session session ssh session
+     */
+    public static void disconnect(Session session) {
+        if (session.isConnected()) {
+            session.disconnect();
+        }
+    }
+
+    /**
+     * Fetches last term after executing command.
+     * @param session  ssh session
+     * @param command command to execute
+     * @return last term, or null
+     */
+    public static String fetchLastTerm(Session session, String command) {
+         if (session == null || !session.isConnected()) {
+             log.error("Invalid session({})", session);
+             return null;
+         }
+
+         log.info("fetchLastTerm: ssh command {} to {}", command, session.getHost());
+
+         try {
+             Channel channel = session.openChannel("exec");
+             if (channel == null) {
+                 log.error("Invalid channel of session({}) for command({})", session, command);
+                 return null;
+             }
+
+             ((ChannelExec) channel).setCommand(command);
+             channel.setInputStream(null);
+             InputStream output = channel.getInputStream();
+             channel.connect();
+             String[] lineList = null;
+
+             try (BufferedReader reader = new BufferedReader(new InputStreamReader(output, StandardCharsets.UTF_8))) {
+                 lineList = reader.lines().findFirst().get().split(SPACESEPERATOR);
+             } catch (IOException e) {
+                 log.error("Exception in fetchLastTerm", e);
+             } finally {
+                 channel.disconnect();
+                 output.close();
+             }
+
+             if (lineList.length > 0) {
+                 return lineList[lineList.length - 1];
+             } else {
+                 return null;
+             }
+
+         } catch (JSchException | IOException e) {
+             log.error("Exception in fetchLastTerm", e);
+             return null;
+         }
+    }
+
+    /**
+     * Executes a given command. It opens exec channel for the command and closes
+     * the channel when it's done.
+     *
+     * @param session ssh connection to a remote server
+     * @param command command to execute
+     * @return command output string if the command succeeds, or null
+     */
+    public static String executeCommand(Session session, String command) {
+        if (session == null || !session.isConnected()) {
+            log.error("Invalid session({})", session);
+            return null;
+        }
+
+        log.info("executeCommand: ssh command {} to {}", command, session.getHost());
+
+        try {
+            Channel channel = session.openChannel("exec");
+
+            if (channel == null) {
+                log.debug("Invalid channel of session({}) for command({})", session, command);
+                return null;
+            }
+
+            ((ChannelExec) channel).setCommand(command);
+            channel.setInputStream(null);
+            InputStream output = channel.getInputStream();
+
+            channel.connect();
+            String result = CharStreams.toString(new InputStreamReader(output, StandardCharsets.UTF_8));
+            log.trace("SSH result(on {}): {}", session.getHost(), result);
+            channel.disconnect();
+
+            return result;
+        } catch (JSchException | IOException e) {
+            log.debug("Failed to execute command {} due to {}", command, e);
+            return null;
+        }
+    }
+
+    /**
+     * Fetches OVS version information.
+     * @param session Jsch session
+     * @return OVS version
+     * @throws WorkflowException workflow exception
+     */
+    public static OvsVersion fetchOvsVersion(Session session) throws WorkflowException {
+
+        OvsVersion devOvsVersion;
+
+        String ovsVersionStr = fetchLastTerm(session, "ovs-vswitchd --version");
+        if (ovsVersionStr == null) {
+            log.error("Failed to get ovs Version String for ssh session:{}", session);
+            throw new WorkflowException("Failed to get ovs Version String");
+        }
+
+        devOvsVersion = OvsVersion.build(ovsVersionStr);
+        if (devOvsVersion == null) {
+            log.error("Failed to build OVS version for {}", ovsVersionStr);
+            throw new WorkflowException("Failed to build OVS version");
+        }
+
+        return devOvsVersion;
+    }
+
+    private static final String IP_PATTERN = "^([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\." +
+            "([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\." +
+            "([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\." +
+            "([01]?\\d\\d?|2[0-4]\\d|25[0-5])$";
+
+    private static boolean isIPv6(String address) {
+        boolean isCorrect = true;
+        try {
+            IpAddress.valueOf(address);
+        } catch (IllegalArgumentException e) {
+            log.debug("Exception Occurred {}", e.toString());
+            isCorrect = false;
+        }
+        return isCorrect;
+    }
+
+    private static boolean isCidr(String s) {
+        String[] splits = s.split("/");
+        return splits.length == 2 &&
+                (splits[0].matches(IP_PATTERN) || isIPv6(splits[0]));
+    }
+
+    /**
+     * Adds IP address on the interface.
+     * @param session SSH session
+     * @param ifname interface name
+     * @param address network address
+     * @throws WorkflowException workflow exception
+     */
+    public static void addIpAddrOnInterface(Session session, String ifname, NetworkAddress address)
+            throws WorkflowException {
+
+        executeCommand(session, String.format("ip addr add %s dev %s", address.cidr(), ifname));
+
+        Set<NetworkAddress> result = getIpAddrOfInterface(session, ifname);
+        if (!result.contains(address)) {
+            throw new WorkflowException("Failed to set ip(" + address + ") on " + ifname + ",  result: " + result);
+        }
+    }
+
+    /**
+     * Gets IP addresses of interface.
+     * @param session SSH session
+     * @param ifname interface name
+     * @return IP addresses of interface
+     */
+    public static Set<NetworkAddress> getIpAddrOfInterface(Session session, String ifname) {
+
+        String output = executeCommand(session, String.format("ip addr show %s", ifname));
+
+        if (output == null) {
+            return Collections.emptySet();
+        }
+
+        Set<NetworkAddress> result = Pattern.compile(" ")
+                .splitAsStream(output)
+                .filter(SshUtil::isCidr)
+                .map(NetworkAddress::valueOf)
+                .collect(Collectors.toSet());
+        return result;
+    }
+
+    /**
+     * Returns whether the interface has IP address.
+     * @param session SSH session
+     * @param ifname interface name
+     * @param addr network address
+     * @return whether the interface has IP address
+     */
+    public static boolean hasIpAddrOnInterface(Session session, String ifname, NetworkAddress addr) {
+
+        Set<NetworkAddress> phyBrIps = getIpAddrOfInterface(session, ifname);
+
+        return phyBrIps.stream()
+                .anyMatch(ip -> addr.ip().equals(ip.ip()));
+    }
+
+    /**
+     * Sets IP link UP on the interface.
+     * @param session SSH session
+     * @param ifname interface name
+     * @throws WorkflowException workflow exception
+     */
+    public static void setIpLinkUpOnInterface(Session session, String ifname)
+            throws WorkflowException {
+
+        executeCommand(session, String.format("ip link set %s up", ifname));
+
+        if (!isIpLinkUpOnInterface(session, ifname)) {
+            throw new WorkflowException("Failed to set UP on " + ifname);
+        }
+    }
+
+    /**
+     * Returns whether the link of the interface is up.
+     * @param session SSH session
+     * @param ifname interface name
+     * @return whether the link of the interface is up
+     */
+    public static boolean isIpLinkUpOnInterface(Session session, String ifname) {
+        String output = executeCommand(session, String.format("ip link show %s", ifname));
+
+        return output != null && output.contains("UP");
+    }
+
+    /**
+     * Executes SSH behavior.
+     * @param sshAccessInfo SSH Access information
+     * @param behavior SSH behavior
+     * @param <R> Return type of SSH behavior
+     * @return return of SSH behavior
+     * @throws WorkflowException workflow exception
+     */
+    public static <R> R exec(SshAccessInfo sshAccessInfo, SshBehavior<R> behavior)
+            throws WorkflowException {
+
+        check(sshAccessInfo != null, "Invalid sshAccessInfo");
+        Session session = connect(sshAccessInfo);
+        if (session == null || !session.isConnected()) {
+            log.error("Failed to get session for ssh:{}", sshAccessInfo);
+            throw new WorkflowException("Failed to get session for ssh:" + sshAccessInfo);
+        }
+
+        try {
+            return behavior.apply(session);
+        } finally {
+            disconnect(session);
+        }
+    }
+
+}
diff --git a/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/SshkeyExchange.java b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/SshkeyExchange.java
new file mode 100644
index 0000000..5615112
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/SshkeyExchange.java
@@ -0,0 +1,198 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.ofoverlay.impl.util;
+
+import com.jcraft.jsch.Channel;
+import com.jcraft.jsch.ChannelSftp;
+import com.jcraft.jsch.JSch;
+import com.jcraft.jsch.JSchException;
+import com.jcraft.jsch.KeyPair;
+import com.jcraft.jsch.Session;
+import com.jcraft.jsch.SftpATTRS;
+import com.jcraft.jsch.SftpException;
+import org.onlab.packet.IpAddress;
+import org.slf4j.Logger;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Class for SSH key exchange.
+ */
+public class SshkeyExchange {
+
+    protected static final Logger log = getLogger(SshkeyExchange.class);
+    private static final String HOME_ENV = System.getProperty("user.home");
+    private static final String USER_ENV = System.getProperty("user.name");
+    private static final String PUBLIC_KEY = "/.ssh/id_rsa.pub";
+    private static final String PRIVATE_KEY = "/.ssh/id_rsa";
+    private static final String SFTP_CHANNEL = "sftp";
+    private static final String SSH_HOME = "/.ssh/";
+    private static final String SSH_AUTH_KEY = "/.ssh/authorized_keys";
+    private static final int SFTPPORT = 22;
+    private static final int DIR_PER = 448;
+    private static final int FILE_PER = 384;
+    private static final int KEY_SIZE = 2048;
+    private static final int DEFAULT_SESSION_TIMEOUT = 30000; // milliseconds
+
+    private Session getJschSession(String user, String host, String password) {
+        java.util.Properties config = new java.util.Properties();
+        config.put("StrictHostKeyChecking", "no");
+        Session session;
+        try {
+            session = new JSch().getSession(user, host, SFTPPORT);
+            session.setPassword(password);
+            session.setConfig(config);
+        } catch (JSchException e) {
+            log.error("Exception in getJschSession", e);
+            return null;
+        }
+
+        return session;
+    }
+
+    private boolean generateKeyPair() {
+        KeyPair kpair;
+        StringBuilder command = new StringBuilder()
+                .append("chmod 600 ")
+                .append(HOME_ENV)
+                .append(PRIVATE_KEY);
+        try {
+            kpair = KeyPair.genKeyPair(new JSch(), KeyPair.RSA, KEY_SIZE);
+            kpair.writePrivateKey(HOME_ENV + PRIVATE_KEY);
+            kpair.writePublicKey(HOME_ENV + PUBLIC_KEY, USER_ENV);
+            Runtime.getRuntime().exec(command.toString());
+            kpair.dispose();
+        } catch (JSchException | IOException e) {
+            log.error("Exception in generateKeyPair", e);
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Exchanges SSH key.
+     * @param host SSH server host
+     * @param user user
+     * @param password password
+     * @return SSH key exchange success or not
+     */
+    public boolean sshAutoKeyExchange(IpAddress host, String user, String password) {
+
+        Session session = getJschSession(user, host.toString(), password);
+        boolean returnFlag;
+        File publickeyPath = new File(HOME_ENV + PUBLIC_KEY);
+        if (session == null) {
+            log.error("Error While establishing SFTP connection with {}", host.toString());
+            return false;
+        }
+        Channel channel;
+        String remoteHome;
+        ChannelSftp sftp;
+        FileInputStream fis = null;
+        SftpATTRS attrs = null;
+        try {
+            session.connect(DEFAULT_SESSION_TIMEOUT);
+            channel = session.openChannel(SFTP_CHANNEL);
+            if (channel == null) {
+                log.error("SFTP channel open failed for {}", host.toString());
+                return false;
+            }
+            channel.connect();
+            sftp = (ChannelSftp) channel;
+            remoteHome = sftp.getHome();
+            // checking key pair existance
+
+            if (!publickeyPath.exists()) {
+                File dirs = new File(HOME_ENV + SSH_HOME);
+                if (!dirs.exists() && !dirs.mkdirs()) {
+                    log.error("{} not exists and unable to create ", dirs.getPath());
+                    return false;
+                } else if (!generateKeyPair()) {
+                    log.error("SSH Key pair generation failed");
+                    return false;
+                }
+            }
+
+            // checking for authenticate_keys file existance
+            fis = new FileInputStream(publickeyPath);
+            try {
+                sftp.lstat(remoteHome + SSH_HOME);
+            } catch (SftpException e) {
+                sftp.mkdir(remoteHome + SSH_HOME);
+                sftp.chmod(700, remoteHome + SSH_HOME);
+            }
+            try {
+                attrs = sftp.lstat(remoteHome + SSH_AUTH_KEY);
+            } catch (SftpException e) {
+                log.info("authorized_keys file does not exist at remote device ,"
+                        + "a new file will be created");
+            }
+
+            if (attrs != null) {
+                sftp.get(remoteHome + SSH_AUTH_KEY, HOME_ENV + "/tempauthorized_keys");
+
+                String pubKey;
+                try (Stream<String> st = Files.lines(Paths.get(HOME_ENV + PUBLIC_KEY))) {
+                    pubKey = st.collect(Collectors.joining());
+                }
+
+                String authKey;
+                try (Stream<String> st = Files.lines(Paths.get(HOME_ENV + "/tempauthorized_keys"))) {
+                    authKey = st.collect(Collectors.joining());
+                }
+
+                if (authKey.contains(pubKey)) {
+                    log.info("Skipping key append to server as Key is already added");
+                } else {
+                    sftp.put(fis, remoteHome + SSH_AUTH_KEY, ChannelSftp.APPEND);
+                    log.info("Public key appended to server");
+                }
+            } else {
+
+                sftp.put(fis, remoteHome + SSH_AUTH_KEY, ChannelSftp.APPEND);
+                // Give proper permission to file and directory.
+                sftp.chmod(DIR_PER, remoteHome + SSH_HOME);
+                sftp.chmod(FILE_PER, remoteHome + SSH_AUTH_KEY);
+                log.info("Public key appended to server");
+            }
+
+            sftp.exit();
+            session.disconnect();
+            returnFlag = true;
+        } catch (JSchException | SftpException | IOException e) {
+            log.error("Exception occured because of {} ", e);
+            returnFlag = false;
+        } finally {
+            if (fis != null) {
+                try {
+                    fis.close();
+                } catch (IOException e) {
+                    log.info("Error closing public key file");
+                }
+            }
+        }
+        return returnFlag;
+
+    }
+}
diff --git a/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/package-info.java b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/package-info.java
new file mode 100644
index 0000000..c76ba58
--- /dev/null
+++ b/apps/workflow/ofoverlay/app/src/main/java/org/onosproject/ofoverlay/impl/util/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Utility classes of ofoverlay.
+ */
+package org.onosproject.ofoverlay.impl.util;
\ No newline at end of file
diff --git a/apps/workflow/ofoverlay/test-cfg/empty.json b/apps/workflow/ofoverlay/test-cfg/empty.json
new file mode 100755
index 0000000..2691a31
--- /dev/null
+++ b/apps/workflow/ofoverlay/test-cfg/empty.json
@@ -0,0 +1,12 @@
+{
+    "apps": {
+        "org.onosproject.workflow": {
+          "workflow" : {
+            "rpc" : [
+            ]
+
+          }
+
+        }
+    }
+}
diff --git a/apps/workflow/ofoverlay/test-cfg/network-cfg-cr-wf.json b/apps/workflow/ofoverlay/test-cfg/network-cfg-cr-wf.json
new file mode 100755
index 0000000..19e2669
--- /dev/null
+++ b/apps/workflow/ofoverlay/test-cfg/network-cfg-cr-wf.json
@@ -0,0 +1,317 @@
+{
+    "apps": {
+        "org.onosproject.workflow": {
+          "workflow" : {
+            "rpc" : [
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Nova-000",
+                  "id"        : "of-overlay.workflow-nova",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.8",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.8",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "nova0_1" ],
+                    "vtepIp" : "120.0.0.200/24",
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Nova-001",
+                  "id"        : "of-overlay.workflow-nova",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.9",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.9",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "nova1_1" ],
+                    "vtepIp" : "120.0.0.201/24",
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Nova-002",
+                  "id"        : "of-overlay.workflow-nova",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.10",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.10",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "nova2_1" ],
+                    "vtepIp" : "120.0.0.202/24",
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Nova-003",
+                  "id"        : "of-overlay.workflow-nova",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.11",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.11",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "nova3_1" ],
+                    "vtepIp" : "120.0.0.203/24",
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Leaf-000",
+                  "id"        : "of-overlay.workflow-ovs-leaf",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.4",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.4",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "leaf0_0", "leaf0_1", "leaf0_nova00" ],
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Leaf-001",
+                  "id"        : "of-overlay.workflow-ovs-leaf",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.5",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.5",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "leaf1_0", "leaf1_1", "leaf1_nova10" ],
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Leaf-002",
+                  "id"        : "of-overlay.workflow-ovs-leaf",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.6",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.6",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "leaf2_0", "leaf2_1", "leaf2_nova20" ],
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Leaf-003",
+                  "id"        : "of-overlay.workflow-ovs-leaf",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.7",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.7",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "leaf3_0", "leaf3_1", "leaf3_nova30" ],
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Spine-000",
+                  "id"        : "of-overlay.workflow-ovs-spine",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.2",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.2",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "spine0_0", "spine0_1", "spine0_2", "spine0_3" ],
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Spine-001",
+                  "id"        : "of-overlay.workflow-ovs-spine",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.3",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.3",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "spine1_0", "spine1_1", "spine1_2", "spine1_3" ],
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              }
+
+            ]
+          }
+        }
+    }
+}
diff --git a/apps/workflow/ofoverlay/test-cfg/network-cfg-ovs-cr-multiEvent-wf.json b/apps/workflow/ofoverlay/test-cfg/network-cfg-ovs-cr-multiEvent-wf.json
new file mode 100755
index 0000000..6f9d2a5
--- /dev/null
+++ b/apps/workflow/ofoverlay/test-cfg/network-cfg-ovs-cr-multiEvent-wf.json
@@ -0,0 +1,41 @@
+{
+    "apps": {
+        "org.onosproject.workflow": {
+          "workflow" : {
+            "rpc" : [
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Nova-000",
+                  "id"        : "of-overlay.workflow-nova-multiEvent-test",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.8",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.8",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    },
+
+                    "ovsDatapathType" : "system",
+                    "physicalPorts" : [ "enp4s2" ],
+                    "vtepIp" : "120.0.0.200/24",
+
+                    "annotations" : {
+                      "rackId" : 1,
+                      "rackPosition" : 3
+                    }
+
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              }
+            ]
+          }
+        }
+    }
+}
diff --git a/apps/workflow/ofoverlay/test-cfg/network-cfg-ovs-waitAll-rm-bridge-wf.json b/apps/workflow/ofoverlay/test-cfg/network-cfg-ovs-waitAll-rm-bridge-wf.json
new file mode 100755
index 0000000..c9e387e
--- /dev/null
+++ b/apps/workflow/ofoverlay/test-cfg/network-cfg-ovs-waitAll-rm-bridge-wf.json
@@ -0,0 +1,34 @@
+{
+    "apps": {
+        "org.onosproject.workflow": {
+          "workflow" : {
+            "rpc" : [
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Nova-000",
+                  "id"        : "of-overlay.clean-workflow-nova-waitAll-Bridge-Del",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.8",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.8",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    }
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              }
+
+            ]
+
+          }
+
+        }
+    }
+}
diff --git a/apps/workflow/ofoverlay/test-cfg/network-cfg-rm-wf.json b/apps/workflow/ofoverlay/test-cfg/network-cfg-rm-wf.json
new file mode 100755
index 0000000..be554a9
--- /dev/null
+++ b/apps/workflow/ofoverlay/test-cfg/network-cfg-rm-wf.json
@@ -0,0 +1,98 @@
+{
+    "apps": {
+        "org.onosproject.workflow": {
+          "workflow" : {
+            "rpc" : [
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Nova-000",
+                  "id"        : "of-overlay.clean-workflow-nova",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.8",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.8",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    }
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Nova-001",
+                  "id"        : "of-overlay.clean-workflow-nova",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.9",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.9",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    }
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Nova-002",
+                  "id"        : "of-overlay.clean-workflow-nova",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.10",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.10",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    }
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              },
+              {
+                "op"   : "workflow.invoke",
+                "params" : {
+                  "workplace" : "Nova-003",
+                  "id"        : "of-overlay.clean-workflow-nova",
+                  "data"      : {
+
+                    "mgmtIp" : "192.168.10.11",
+                    "ovsdbPort" : 6641,
+
+                    "sshAccessInfo" : {
+                      "remoteIp" : "192.168.10.11",
+                      "port"     : 22,
+                      "user"     : "root",
+                      "password" : "iloveyou",
+                      "keyfile"  : "~/.ssh/id_rsa"
+                    }
+                  }
+                },
+                "id" : "00001@10.0.0.1"
+              }
+
+
+            ]
+
+          }
+
+        }
+    }
+}