diff --git a/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchHandle.java b/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchHandle.java
new file mode 100644
index 0000000..166a12f
--- /dev/null
+++ b/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchHandle.java
@@ -0,0 +1,29 @@
+package net.onrc.onos.api.flowmanager;
+
+/**
+ * Handle class to handle flow batch operation.
+ */
+public class FlowBatchHandle {
+    private final FlowBatchId batchId;
+
+    /**
+     * Creates a handle using batch operation ID.
+     * <p>
+     * The ID is automatically generated and assigned by FlowManager, and used
+     * as an internal key for the flow batch operation map.
+     *
+     * @param id the batch operation ID
+     */
+    public FlowBatchHandle(FlowBatchId id) {
+        batchId = id;
+    }
+
+    /**
+     * Gets the flow batch operation ID.
+     *
+     * @return the flow batch operation ID
+     */
+    public FlowBatchId getBatchOperationId() {
+        return batchId;
+    }
+}
diff --git a/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchId.java b/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchId.java
new file mode 100644
index 0000000..9899adf
--- /dev/null
+++ b/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchId.java
@@ -0,0 +1,8 @@
+package net.onrc.onos.api.flowmanager;
+
+/**
+ * Represents ID for {@link FlowBatchOperation}.
+ */
+public class FlowBatchId {
+    // TODO implement it
+}
diff --git a/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchState.java b/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchState.java
new file mode 100644
index 0000000..fd62a97
--- /dev/null
+++ b/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchState.java
@@ -0,0 +1,27 @@
+package net.onrc.onos.api.flowmanager;
+
+/**
+ * Represents the state of {@link FlowBatchOperation}.
+ */
+public enum FlowBatchState {
+    /**
+     * The operation has been submitted, but the FlowManager is not executing
+     * yet.
+     */
+    SUBMITTED,
+
+    /**
+     * The FlowManager is executing the operation, but not completed yet.
+     */
+    EXECUTING,
+
+    /**
+     * The operation has been executed successfully.
+     */
+    COMPLETED,
+
+    /**
+     * The operation has been failed to be submitted or executed.
+     */
+    FAILED,
+}
diff --git a/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchStateChangedEvent.java b/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchStateChangedEvent.java
new file mode 100644
index 0000000..7b169e6
--- /dev/null
+++ b/src/main/java/net/onrc/onos/api/flowmanager/FlowBatchStateChangedEvent.java
@@ -0,0 +1,64 @@
+package net.onrc.onos.api.flowmanager;
+
+/**
+ * Event class which notifies the state change of flow batch operation.
+ */
+public class FlowBatchStateChangedEvent {
+    private final long time;
+    private final FlowBatchHandle handle;
+    private final FlowBatchState current;
+    private final FlowBatchState previous;
+
+    /**
+     * Creates the {@link FlowBatchStateChangedEvent} instance.
+     *
+     * @param time the time at which the event was created in milliseconds since
+     *        start of epoch
+     * @param handle the handle for the flow batch operation
+     * @param current the current state of the flow batch operation
+     * @param previous the previous state of the flow batch operation
+     */
+    FlowBatchStateChangedEvent(long time, FlowBatchHandle handle,
+            FlowBatchState current, FlowBatchState previous) {
+        this.time = time;
+        this.handle = handle;
+        this.current = current;
+        this.previous = previous;
+    }
+
+    /**
+     * Gets the time at which the event was created.
+     *
+     * @return the time in milliseconds since start of epoch
+     */
+    public long getTime() {
+        return time;
+    }
+
+    /**
+     * Gets the handle for the flow batch operation.
+     *
+     * @return the handle for the flow batch operation
+     */
+    public FlowBatchHandle getFlowBatchHandle() {
+        return handle;
+    }
+
+    /**
+     * Gets the current state of the flow batch operation.
+     *
+     * @return the current state of the flow batch operation
+     */
+    public FlowBatchState getCurrentState() {
+        return current;
+    }
+
+    /**
+     * Gets the previous state of the flow batch operation.
+     *
+     * @return the previous state of the flow batch operation
+     */
+    public FlowBatchState getPreviousState() {
+        return previous;
+    }
+}
diff --git a/src/main/java/net/onrc/onos/api/flowmanager/FlowManagerListener.java b/src/main/java/net/onrc/onos/api/flowmanager/FlowManagerListener.java
new file mode 100644
index 0000000..0e70867
--- /dev/null
+++ b/src/main/java/net/onrc/onos/api/flowmanager/FlowManagerListener.java
@@ -0,0 +1,20 @@
+package net.onrc.onos.api.flowmanager;
+
+/**
+ * An interface to the FlowManager's listener.
+ */
+public interface FlowManagerListener {
+    /**
+     * Handles flow state changes.
+     *
+     * @param event the state changes of the flow objects
+     */
+    public void flowStatesChanged(FlowStatesChangedEvent event);
+
+    /**
+     * Handles flow batch operation's state changes.
+     *
+     * @param event the state changes of the flow batch operations
+     */
+    public void flowBatchStateChanged(FlowBatchStateChangedEvent event);
+}
diff --git a/src/main/java/net/onrc/onos/api/flowmanager/FlowManagerService.java b/src/main/java/net/onrc/onos/api/flowmanager/FlowManagerService.java
index b8e14f4..4812de2 100644
--- a/src/main/java/net/onrc/onos/api/flowmanager/FlowManagerService.java
+++ b/src/main/java/net/onrc/onos/api/flowmanager/FlowManagerService.java
@@ -1,7 +1,6 @@
 package net.onrc.onos.api.flowmanager;
 
 import java.util.Collection;
-import java.util.EventListener;
 
 /**
  * An interface class for flow manager. The role of the flow manager is to
@@ -71,14 +70,14 @@
     /**
      * Adds event listener to this service.
      *
-     * @param listener EventListener to be added
+     * @param listener the listener to be added
      */
-    void addEventListener(EventListener listener);
+    void addListener(FlowManagerListener listener);
 
     /**
      * Removes event listener from this service.
      *
-     * @param listener EventListener to be removed
+     * @param listener the listener to be removed
      */
-    void removeEventListener(EventListener listener);
+    void removeListener(FlowManagerListener listener);
 }
diff --git a/src/main/java/net/onrc/onos/api/flowmanager/FlowState.java b/src/main/java/net/onrc/onos/api/flowmanager/FlowState.java
new file mode 100644
index 0000000..4cb03c7
--- /dev/null
+++ b/src/main/java/net/onrc/onos/api/flowmanager/FlowState.java
@@ -0,0 +1,38 @@
+package net.onrc.onos.api.flowmanager;
+
+/**
+ * Represents the state of the Flow object.
+ */
+public enum FlowState {
+
+    /**
+     * The flow object is submitted, but not compiled yet.
+     */
+    SUBMITTED,
+
+    /**
+     * The match-action plan has been compiled from the flow object, but not
+     * installed yet.
+     */
+    COMPILED,
+
+    /**
+     * The compiled match-action plan has been installed successfully.
+     */
+    INSTALLED,
+
+    /**
+     * The installed flow is withdrawing.
+     */
+    WITHDRAWING,
+
+    /**
+     * The installed flow has been withdrawn successfully.
+     */
+    WITHDRAWN,
+
+    /**
+     * The FlowManager has failed to compile, install or withdraw the flow.
+     */
+    FAILED,
+}
diff --git a/src/main/java/net/onrc/onos/api/flowmanager/FlowStateChange.java b/src/main/java/net/onrc/onos/api/flowmanager/FlowStateChange.java
new file mode 100644
index 0000000..9d7f0d6
--- /dev/null
+++ b/src/main/java/net/onrc/onos/api/flowmanager/FlowStateChange.java
@@ -0,0 +1,50 @@
+package net.onrc.onos.api.flowmanager;
+
+/**
+ * The class which expresses the state changes of Flow object.
+ */
+public class FlowStateChange {
+    private final FlowId flowId;
+    private final FlowState current;
+    private final FlowState previous;
+
+    /**
+     * Creates {@link FlowStateChange} instance.
+     *
+     * @param flowId the ID of the target flow
+     * @param current the current state of the flow
+     * @param previous the previous state of the flow
+     */
+    FlowStateChange(FlowId flowId, FlowState current, FlowState previous) {
+        this.flowId = flowId;
+        this.current = current;
+        this.previous = previous;
+    }
+
+    /**
+     * Gets the ID of the flow.
+     *
+     * @return the flow ID
+     */
+    public FlowId getFlowId() {
+        return flowId;
+    }
+
+    /**
+     * Gets the current state of the flow.
+     *
+     * @return the current state of the flow
+     */
+    public FlowState getCurrentState() {
+        return current;
+    }
+
+    /**
+     * Gets the previous state of the flow.
+     *
+     * @return the previous state of the flow
+     */
+    public FlowState getPreviousState() {
+        return previous;
+    }
+}
diff --git a/src/main/java/net/onrc/onos/api/flowmanager/FlowStatesChangedEvent.java b/src/main/java/net/onrc/onos/api/flowmanager/FlowStatesChangedEvent.java
new file mode 100644
index 0000000..d078fcb
--- /dev/null
+++ b/src/main/java/net/onrc/onos/api/flowmanager/FlowStatesChangedEvent.java
@@ -0,0 +1,44 @@
+package net.onrc.onos.api.flowmanager;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.util.Set;
+
+import com.google.common.collect.ImmutableSet;
+
+/**
+ * The event class which notifies the set of the flow state transitions.
+ */
+public class FlowStatesChangedEvent {
+    private final long time;
+    private final Set<FlowStateChange> changes;
+
+    /**
+     * Creates the {@link FlowStatesChangedEvent} instance.
+     *
+     * @param time the time at which the event was created in milliseconds since start of epoch
+     * @param changes the set of {@link FlowStateChange} objects
+     */
+    FlowStatesChangedEvent(long time, Set<FlowStateChange> changes) {
+        this.time = time;
+        this.changes = ImmutableSet.copyOf(checkNotNull(changes));
+    }
+
+    /**
+     * Gets the time at which the event was created.
+     *
+     * @return the time at which the event was created in milliseconds since start of epoch
+     */
+    public long getTime() {
+        return time;
+    }
+
+    /**
+     * Gets the set of state changes happened at once.
+     *
+     * @return the set of {@link FlowStateChange} objects
+     */
+    public Set<FlowStateChange> getStateChanges() {
+        return changes;
+    }
+}
diff --git a/src/main/java/net/onrc/onos/core/flowmanager/FlowManagerModule.java b/src/main/java/net/onrc/onos/core/flowmanager/FlowManagerModule.java
index 2d184f8..8336095 100644
--- a/src/main/java/net/onrc/onos/core/flowmanager/FlowManagerModule.java
+++ b/src/main/java/net/onrc/onos/core/flowmanager/FlowManagerModule.java
@@ -1,12 +1,12 @@
 package net.onrc.onos.core.flowmanager;
 
 import java.util.Collection;
-import java.util.EventListener;
 
 import net.onrc.onos.api.flowmanager.ConflictDetectionPolicy;
+import net.onrc.onos.api.flowmanager.Flow;
 import net.onrc.onos.api.flowmanager.FlowBatchOperation;
 import net.onrc.onos.api.flowmanager.FlowId;
-import net.onrc.onos.api.flowmanager.Flow;
+import net.onrc.onos.api.flowmanager.FlowManagerListener;
 import net.onrc.onos.api.flowmanager.FlowManagerService;
 
 /**
@@ -73,13 +73,13 @@
     }
 
     @Override
-    public void addEventListener(EventListener listener) {
+    public void addListener(FlowManagerListener listener) {
         // TODO Auto-generated method stub
 
     }
 
     @Override
-    public void removeEventListener(EventListener listener) {
+    public void removeListener(FlowManagerListener listener) {
         // TODO Auto-generated method stub
 
     }
diff --git a/src/main/java/net/onrc/onos/core/flowmanager/FlowOperationMap.java b/src/main/java/net/onrc/onos/core/flowmanager/FlowOperationMap.java
new file mode 100644
index 0000000..744c65e
--- /dev/null
+++ b/src/main/java/net/onrc/onos/core/flowmanager/FlowOperationMap.java
@@ -0,0 +1,8 @@
+package net.onrc.onos.core.flowmanager;
+
+/**
+ * Manages the set of flow operations throughout the ONOS instances.
+ */
+public class FlowOperationMap {
+    // TODO implement it
+}