Introducing concept of a physical or logical region to facilitate
support of geographically distributed cluster and to lay ground
for multiple/filtered topology layouts.

Added implementation of manager and store; unit-tests included.

Change-Id: Ia01673a0b711b8785c0ea68768552c2f61d7ea6d
diff --git a/core/api/src/main/java/org/onosproject/cluster/NodeId.java b/core/api/src/main/java/org/onosproject/cluster/NodeId.java
index e5ab9dc..8b7d540 100644
--- a/core/api/src/main/java/org/onosproject/cluster/NodeId.java
+++ b/core/api/src/main/java/org/onosproject/cluster/NodeId.java
@@ -15,14 +15,19 @@
  */
 package org.onosproject.cluster;
 
-import java.util.Objects;
+import org.onlab.util.Identifier;
 
 /**
  * Controller cluster identity.
  */
-public class NodeId implements Comparable<NodeId> {
+public final class NodeId extends Identifier<String> implements Comparable<NodeId> {
 
-    private final String id;
+    /**
+     * Constructor for serialization.
+     */
+    private NodeId() {
+        super("");
+    }
 
     /**
      * Creates a new cluster node identifier from the specified string.
@@ -30,34 +35,22 @@
      * @param id string identifier
      */
     public NodeId(String id) {
-        this.id = id;
+        super(id);
     }
 
-    @Override
-    public int hashCode() {
-        return id.hashCode();
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-        if (this == obj) {
-            return true;
-        }
-        if (obj instanceof NodeId) {
-            final NodeId other = (NodeId) obj;
-            return Objects.equals(this.id, other.id);
-        }
-        return false;
-    }
-
-    @Override
-    public String toString() {
-        return id;
+    /**
+     * Creates a new cluster node identifier from the specified string.
+     *
+     * @param id string identifier
+     * @return node id
+     */
+    public static NodeId nodeId(String id) {
+        return new NodeId(id);
     }
 
     @Override
     public int compareTo(NodeId that) {
-        return this.id.compareTo(that.id);
+        return identifier.compareTo(that.identifier);
     }
 
 }
diff --git a/core/api/src/main/java/org/onosproject/net/key/DeviceKeyId.java b/core/api/src/main/java/org/onosproject/net/key/DeviceKeyId.java
index 12c1d95..d7cbdbe 100644
--- a/core/api/src/main/java/org/onosproject/net/key/DeviceKeyId.java
+++ b/core/api/src/main/java/org/onosproject/net/key/DeviceKeyId.java
@@ -16,21 +16,18 @@
 
 package org.onosproject.net.key;
 
-import java.util.Objects;
-
-import static com.google.common.base.Preconditions.checkNotNull;
+import org.onlab.util.Identifier;
 
 /**
- * Device key Id definition.
+ * Device key identifier backed by a string value.
  */
-public final class DeviceKeyId {
-    private final String identifier;
+public final class DeviceKeyId extends Identifier<String> {
 
     /**
      * Constructor for serialization.
      */
     private DeviceKeyId() {
-        this.identifier = null;
+        super();
     }
 
     /**
@@ -39,63 +36,17 @@
      * @param value the underlying value of this ID
      */
     private DeviceKeyId(String value) {
-        this.identifier = checkNotNull(value, "Device Key Id cannot be null.");
+        super(value);
     }
 
     /**
-     * Static  method to construct a device key identifier.
+     * Creates a new device key identifier.
      *
-     * @param id for the device key identifier
+     * @param id backing identifier value
      * @return device key identifier
      */
-    public static final DeviceKeyId deviceKeyId(String id) {
+    public static DeviceKeyId deviceKeyId(String id) {
         return new DeviceKeyId(id);
     }
 
-    /**
-     * Returns the identifier of the device key identifier.
-     *
-     * @return identifier
-     */
-    public String id() {
-        return identifier;
-    }
-
-    /**
-     * Returns the hashcode of the identifier.
-     *
-     * @return hashcode
-     */
-    @Override
-    public int hashCode() {
-        return identifier.hashCode();
-    }
-
-    /**
-     * Compares two device key identifiers for equality.
-     *
-     * @param obj to compare against
-     * @return true if the objects are equal, false otherwise.
-     */
-    @Override
-    public boolean equals(Object obj) {
-        if (this == obj) {
-            return true;
-        }
-        if (obj instanceof DeviceKeyId) {
-            final DeviceKeyId that = (DeviceKeyId) obj;
-            return this.getClass() == that.getClass() &&
-                    Objects.equals(this.identifier, that.identifier);
-        }
-        return false;
-    }
-
-    /**
-     * Returns a string representation of a DeviceKeyId.
-     *
-     * @return string
-     */
-    public String toString() {
-        return identifier;
-    }
 }
diff --git a/core/api/src/main/java/org/onosproject/net/region/DefaultRegion.java b/core/api/src/main/java/org/onosproject/net/region/DefaultRegion.java
new file mode 100644
index 0000000..d828880
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/region/DefaultRegion.java
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.net.region;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.collect.ImmutableList;
+import org.onosproject.cluster.NodeId;
+
+import java.util.List;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * Default implementation of a region.
+ */
+public final class DefaultRegion implements Region {
+
+    private final RegionId id;
+    private final String name;
+    private final Type type;
+    private final List<Set<NodeId>> masters;
+
+    /**
+     * Creates a region using the supplied information.
+     *
+     * @param id      region identifier
+     * @param name    friendly name
+     * @param type    region type
+     * @param masters list of sets of cluster node identifiers; in order of mastership
+     */
+    public DefaultRegion(RegionId id, String name, Type type, List<Set<NodeId>> masters) {
+        this.id = id;
+        this.name = name;
+        this.type = type;
+        this.masters = masters != null ? ImmutableList.copyOf(masters) : ImmutableList.of();
+    }
+
+    @Override
+    public RegionId id() {
+        return id;
+    }
+
+    @Override
+    public String name() {
+        return name;
+    }
+
+    @Override
+    public Type type() {
+        return type;
+    }
+
+    @Override
+    public List<Set<NodeId>> masters() {
+        return masters;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, name, type, masters);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj instanceof DefaultRegion) {
+            final DefaultRegion that = (DefaultRegion) obj;
+            return Objects.equals(this.id, that.id)
+                    && Objects.equals(this.name, that.name)
+                    && Objects.equals(this.type, that.type)
+                    && Objects.equals(this.masters, that.masters);
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(this)
+                .add("id", id)
+                .add("name", name)
+                .add("type", type)
+                .add("masters", masters)
+                .toString();
+    }
+
+}
diff --git a/core/api/src/main/java/org/onosproject/net/region/Region.java b/core/api/src/main/java/org/onosproject/net/region/Region.java
new file mode 100644
index 0000000..3a9f60a
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/region/Region.java
@@ -0,0 +1,112 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.net.region;
+
+import org.onosproject.cluster.NodeId;
+
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Representation of a group of devices located in a common physical or
+ * logical region. Optionally, devices in the region can share the same
+ * cluster nodes mastership affinities.
+ */
+public interface Region {
+
+    /**
+     * Coarse representation of the type of the region.
+     */
+    enum Type {
+        /**
+         * Region represents an entire continent.
+         */
+        CONTINENT,
+
+        /**
+         * Region represents an entire country.
+         */
+        COUNTRY,
+
+        /**
+         * Region represents a metropolitan area.
+         */
+        METRO,
+
+        /**
+         * Region represents a campus.
+         */
+        CAMPUS,
+
+        /**
+         * Region represents a building.
+         */
+        BUILDING,
+
+        /**
+         * Region represents a building floor.
+         */
+        FLOOR,
+
+        /**
+         * Region represents a room.
+         */
+        ROOM,
+
+        /**
+         * Region represents a rack.
+         */
+        RACK,
+
+        /**
+         * Region represents a logical grouping.
+         */
+        LOGICAL_GROUP
+    }
+
+    /**
+     * Returns the unique identifier of the region.
+     *
+     * @return region identifier
+     */
+    RegionId id();
+
+    /**
+     * Returns the friendly region name that can be used for display purposes.
+     *
+     * @return friendly name of the region
+     */
+    String name();
+
+    /**
+     * Returns the region type.
+     *
+     * @return region type
+     */
+    Type type();
+
+    /**
+     * Returns the list of master node sets. The sets of cluster node identifiers
+     * should be listed in the order of preferred mastership. Nodes specified
+     * in each sets should be considered with equally priority and devices in
+     * the region can be balanced between them based on other criteria, e.g. load.
+     *
+     * @return list of preferred master node sets
+     */
+    List<Set<NodeId>> masters();
+
+}
diff --git a/core/api/src/main/java/org/onosproject/net/region/RegionAdminService.java b/core/api/src/main/java/org/onosproject/net/region/RegionAdminService.java
new file mode 100644
index 0000000..e402a7d
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/region/RegionAdminService.java
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.net.region;
+
+import org.onosproject.cluster.NodeId;
+import org.onosproject.net.DeviceId;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Service for interacting with inventory of network control regions.
+ */
+public interface RegionAdminService extends RegionService {
+
+    /**
+     * Creates a new region using the supplied data.
+     *
+     * @param regionId      region identifier
+     * @param name          friendly name
+     * @param type          region type
+     * @param masterNodeIds list of sets of master nodes; null implies empty list
+     * @return new region descriptor
+     * @throws IllegalArgumentException if region already exists
+     */
+    Region createRegion(RegionId regionId, String name, Region.Type type,
+                        List<Set<NodeId>> masterNodeIds);
+
+    /**
+     * Update the specified region using the new set of data.
+     *
+     * @param regionId      region identifier
+     * @param name          friendly name
+     * @param type          region type
+     * @param masterNodeIds list of sets of master nodes; null implies empty list
+     * @return new region descriptor
+     */
+    Region updateRegion(RegionId regionId, String name, Region.Type type,
+                        List<Set<NodeId>> masterNodeIds);
+
+    /**
+     * Removes the specified region using the new set of data.
+     *
+     * @param regionId region identifier
+     */
+    void removeRegion(RegionId regionId);
+
+    /**
+     * Adds the specified collection of devices to the region.
+     *
+     * @param regionId  region identifier
+     * @param deviceIds list of device identifiers
+     */
+    void addDevices(RegionId regionId, Collection<DeviceId> deviceIds);
+
+    /**
+     * Removes the specified collection of devices from the region.
+     *
+     * @param regionId  region identifier
+     * @param deviceIds list of device identifiers
+     */
+    void removeDevices(RegionId regionId, Collection<DeviceId> deviceIds);
+
+}
diff --git a/core/api/src/main/java/org/onosproject/net/region/RegionEvent.java b/core/api/src/main/java/org/onosproject/net/region/RegionEvent.java
new file mode 100644
index 0000000..6f0abd8
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/region/RegionEvent.java
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.net.region;
+
+import com.google.common.collect.ImmutableSet;
+import org.onosproject.event.AbstractEvent;
+import org.onosproject.net.DeviceId;
+
+import java.util.Set;
+
+/**
+ * Describes region event.
+ */
+public class RegionEvent extends AbstractEvent<RegionEvent.Type, Region> {
+
+    private final Set<DeviceId> deviceIds;
+
+    public enum Type {
+        /**
+         * Signifies that a new region was created.
+         */
+        REGION_ADDED,
+
+        /**
+         * Signifies that a region was updated.
+         */
+        REGION_REMOVED,
+
+        /**
+         * Signifies that a region was removed.
+         */
+        REGION_UPDATED,
+
+        /**
+         * Signifies that a region device membership has changed.
+         */
+        REGION_MEMBERSHIP_CHANGED
+    }
+
+    /**
+     * Creates an event of a given type and for the specified region and the
+     * current time.
+     *
+     * @param type   device event type
+     * @param region event region subject
+     */
+    public RegionEvent(Type type, Region region) {
+        this(type, region, null);
+    }
+
+    /**
+     * Creates an event of a given type and for the specified region, device
+     * id list and the current time.
+     *
+     * @param type      device event type
+     * @param region    event region subject
+     * @param deviceIds optional set of device ids
+     */
+    public RegionEvent(Type type, Region region, Set<DeviceId> deviceIds) {
+        super(type, region);
+        this.deviceIds = deviceIds != null ? ImmutableSet.copyOf(deviceIds) : ImmutableSet.of();
+    }
+
+    /**
+     * Creates an event of a given type and for the specified device and time.
+     *
+     * @param type      device event type
+     * @param region    event region subject
+     * @param deviceIds optional set of device ids
+     * @param time      occurrence time
+     */
+    public RegionEvent(Type type, Region region, Set<DeviceId> deviceIds, long time) {
+        super(type, region, time);
+        this.deviceIds = deviceIds != null ? ImmutableSet.copyOf(deviceIds) : ImmutableSet.of();
+    }
+
+}
diff --git a/core/api/src/main/java/org/onosproject/net/region/RegionId.java b/core/api/src/main/java/org/onosproject/net/region/RegionId.java
new file mode 100644
index 0000000..0754f6e
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/region/RegionId.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.net.region;
+
+import org.onlab.util.Identifier;
+
+/**
+ * Region identifier backed by a string value.
+ */
+public final class RegionId extends Identifier<String> {
+
+    /**
+     * Constructor for serialization.
+     */
+    private RegionId() {
+        super();
+    }
+
+    /**
+     * Constructs the ID corresponding to a given string value.
+     *
+     * @param value the underlying value of this ID
+     */
+    private RegionId(String value) {
+        super(value);
+    }
+
+    /**
+     * Creates a new region identifier.
+     *
+     * @param id backing identifier value
+     * @return region identifier
+     */
+    public static RegionId regionId(String id) {
+        return new RegionId(id);
+    }
+
+}
diff --git a/core/api/src/main/java/org/onosproject/net/region/RegionListener.java b/core/api/src/main/java/org/onosproject/net/region/RegionListener.java
new file mode 100644
index 0000000..1a41c76
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/region/RegionListener.java
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.net.region;
+
+import org.onosproject.event.EventListener;
+
+/**
+ * Entity capable of receiving region related events.
+ */
+public interface RegionListener extends EventListener<RegionEvent> {
+}
diff --git a/core/api/src/main/java/org/onosproject/net/region/RegionService.java b/core/api/src/main/java/org/onosproject/net/region/RegionService.java
new file mode 100644
index 0000000..9f16aff
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/region/RegionService.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.net.region;
+
+import org.onosproject.net.DeviceId;
+
+import java.util.Set;
+
+/**
+ * Service for interacting with inventory of network control regions.
+ */
+public interface RegionService {
+
+    /**
+     * Returns set of all regions.
+     *
+     * @return set of regions
+     */
+    Set<Region> getRegions();
+
+    /**
+     * Returns the region with the specified identifier.
+     *
+     * @param regionId region identifier
+     * @return region
+     * @throws org.onlab.util.ItemNotFoundException if region with given
+     *                                              id does not exist
+     */
+    Region getRegion(RegionId regionId);
+
+    /**
+     * Returns the region to which the specified device belongs.
+     *
+     * @param deviceId device identifier
+     * @return region or null if device does not belong to any region
+     */
+    Region getRegionForDevice(DeviceId deviceId);
+
+    /**
+     * Returns the set of devices that belong to the specified region.
+     *
+     * @param regionId region identifier
+     * @return set of identifiers for devices in the given region
+     */
+    Set<DeviceId> getRegionDevices(RegionId regionId);
+
+}
diff --git a/core/api/src/main/java/org/onosproject/net/region/RegionStore.java b/core/api/src/main/java/org/onosproject/net/region/RegionStore.java
new file mode 100644
index 0000000..6ba1354
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/region/RegionStore.java
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.net.region;
+
+import org.onosproject.cluster.NodeId;
+import org.onosproject.net.DeviceId;
+import org.onosproject.store.Store;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Manages inventory of regions of devices; not intended for direct use.
+ */
+public interface RegionStore extends Store<RegionEvent, RegionStoreDelegate> {
+
+    /**
+     * Returns set of all regions.
+     *
+     * @return set of regions
+     */
+    Set<Region> getRegions();
+
+    /**
+     * Returns the region with the specified identifier.
+     *
+     * @param regionId region identifier
+     * @return region
+     * @throws org.onlab.util.ItemNotFoundException if region with given
+     *                                              id does not exist
+     */
+    Region getRegion(RegionId regionId);
+
+    /**
+     * Returns the region to which the specified device belongs.
+     *
+     * @param deviceId device identifier
+     * @return region or null if device does not belong to any region
+     */
+    Region getRegionForDevice(DeviceId deviceId);
+
+    /**
+     * Returns the set of devices that belong to the specified region.
+     *
+     * @param regionId region identifier
+     * @return set of identifiers for devices in the given region
+     */
+    Set<DeviceId> getRegionDevices(RegionId regionId);
+
+    /**
+     * Creates a new region using the supplied data.
+     *
+     * @param regionId      region identifier
+     * @param name          friendly name
+     * @param type          region type
+     * @param masterNodeIds list of master nodes; null implies empty list
+     * @return new region descriptor
+     * @throws IllegalArgumentException if item already exists
+     */
+    Region createRegion(RegionId regionId, String name, Region.Type type,
+                        List<Set<NodeId>> masterNodeIds);
+
+    /**
+     * Updates the specified new region using the supplied data.
+     *
+     * @param regionId      region identifier
+     * @param name          friendly name
+     * @param type          region type
+     * @param masterNodeIds list of master nodes; null implies empty list
+     * @return new region descriptor
+     * @throws IllegalArgumentException if item already exists
+     */
+    Region updateRegion(RegionId regionId, String name, Region.Type type,
+                        List<Set<NodeId>> masterNodeIds);
+
+    /**
+     * Removes the specified region using the new set of data.
+     *
+     * @param regionId region identifier
+     */
+    void removeRegion(RegionId regionId);
+
+    /**
+     * Adds the specified collection of devices to the region.
+     *
+     * @param regionId  region identifier
+     * @param deviceIds list of device identifiers
+     */
+    void addDevices(RegionId regionId, Collection<DeviceId> deviceIds);
+
+    /**
+     * Removes the specified collection of devices from the region.
+     *
+     * @param regionId  region identifier
+     * @param deviceIds list of device identifiers
+     */
+    void removeDevices(RegionId regionId, Collection<DeviceId> deviceIds);
+
+}
diff --git a/core/api/src/main/java/org/onosproject/net/region/RegionStoreDelegate.java b/core/api/src/main/java/org/onosproject/net/region/RegionStoreDelegate.java
new file mode 100644
index 0000000..be0c0bb
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/region/RegionStoreDelegate.java
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.net.region;
+
+import org.onosproject.store.StoreDelegate;
+
+/**
+ * Region store delegate abstraction.
+ */
+public interface RegionStoreDelegate extends StoreDelegate<RegionEvent> {
+}
diff --git a/core/api/src/main/java/org/onosproject/net/region/package-info.java b/core/api/src/main/java/org/onosproject/net/region/package-info.java
new file mode 100644
index 0000000..9f6bafd
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/region/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.
+ */
+
+/**
+ * Subsystem for tracking inventory of network control regions.
+ */
+package org.onosproject.net.region;
\ No newline at end of file