diff --git a/src/main/java/net/floodlightcontroller/core/FloodlightProvider.java b/src/main/java/net/floodlightcontroller/core/FloodlightProvider.java
index 95daf96..4d85b7d 100644
--- a/src/main/java/net/floodlightcontroller/core/FloodlightProvider.java
+++ b/src/main/java/net/floodlightcontroller/core/FloodlightProvider.java
@@ -15,6 +15,7 @@
 import net.floodlightcontroller.restserver.IRestApiService;
 import net.floodlightcontroller.storage.IStorageSourceService;
 import net.floodlightcontroller.threadpool.IThreadPoolService;
+import net.onrc.onos.ofcontroller.linkdiscovery.ILinkDiscoveryService;
 import net.onrc.onos.registry.controller.IControllerRegistryService;
 
 public class FloodlightProvider implements IFloodlightModule {
@@ -52,6 +53,7 @@
         dependencies.add(IThreadPoolService.class);
         // Following added by ONOS
         dependencies.add(IControllerRegistryService.class);
+        dependencies.add(ILinkDiscoveryService.class);
 
         return dependencies;
     }
@@ -71,6 +73,8 @@
        // Following added by ONOS
        controller.setMastershipService(
     		   context.getServiceImpl(IControllerRegistryService.class));
+       controller.setLinkDiscoveryService(
+    		   context.getServiceImpl(ILinkDiscoveryService.class));
 
        controller.init(context.getConfigParams(this));
     }
diff --git a/src/main/java/net/floodlightcontroller/core/internal/Controller.java b/src/main/java/net/floodlightcontroller/core/internal/Controller.java
index 17f1be8..31f80cc 100644
--- a/src/main/java/net/floodlightcontroller/core/internal/Controller.java
+++ b/src/main/java/net/floodlightcontroller/core/internal/Controller.java
@@ -75,6 +75,7 @@
 import net.floodlightcontroller.storage.StorageException;
 import net.floodlightcontroller.threadpool.IThreadPoolService;
 import net.onrc.onos.ofcontroller.core.IOFSwitchPortListener;
+import net.onrc.onos.ofcontroller.linkdiscovery.ILinkDiscoveryService;
 import net.onrc.onos.registry.controller.IControllerRegistryService;
 import net.onrc.onos.registry.controller.IControllerRegistryService.ControlChangeCallback;
 import net.onrc.onos.registry.controller.RegistryException;
@@ -189,6 +190,8 @@
     protected IThreadPoolService threadPool;
     protected IControllerRegistryService registryService;
     
+    protected ILinkDiscoveryService linkDiscovery;
+    
     // Configuration options
     protected int openFlowPort = 6633;
     protected int workerThreads = 0;
@@ -407,6 +410,10 @@
 		this.registryService = serviceImpl;		
 	}
 	
+	public void setLinkDiscoveryService(ILinkDiscoveryService linkDiscovery) {
+		this.linkDiscovery = linkDiscovery;
+	}
+	
     @Override
     public Role getRole() {
         synchronized(roleChanger) {
@@ -1298,6 +1305,12 @@
                 updatePortInfo(sw, port);
             log.debug("Port #{} modified for {}", portNumber, sw);
         } else if (m.getReason() == (byte)OFPortReason.OFPPR_ADD.ordinal()) {
+        	// XXX Workaround to prevent race condition where a link is detected
+        	// and attempted to be written to the database before the port is in
+        	// the database. We now suppress link discovery on ports until we're
+        	// sure they're in the database.
+        	linkDiscovery.AddToSuppressLLDPs(sw.getId(), port.getPortNumber());
+        	
             sw.setPort(port);
             SwitchUpdate update = new SwitchUpdate(sw, port, SwitchUpdateType.PORTADDED);
             try {
@@ -1541,6 +1554,14 @@
                     "network problem that can be ignored."
             )
     protected void addSwitch(IOFSwitch sw) {
+    	// XXX Workaround to prevent race condition where a link is detected
+    	// and attempted to be written to the database before the port is in
+    	// the database. We now suppress link discovery on ports until we're
+    	// sure they're in the database.
+    	for (OFPhysicalPort port : sw.getPorts()) {
+    		linkDiscovery.AddToSuppressLLDPs(sw.getId(), port.getPortNumber());
+    	}
+    	
         // TODO: is it safe to modify the HashMap without holding 
         // the old switch's lock?
         OFSwitchImpl oldSw = (OFSwitchImpl) this.activeSwitches.put(sw.getId(), sw);
diff --git a/src/main/java/net/onrc/onos/ofcontroller/core/INetMapTopologyObjects.java b/src/main/java/net/onrc/onos/ofcontroller/core/INetMapTopologyObjects.java
index 869333b..49ffd4e 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/core/INetMapTopologyObjects.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/core/INetMapTopologyObjects.java
@@ -117,6 +117,7 @@
 		@Adjacency(label="host")
 		public void removeDevice(final IDeviceObject device);
 		
+		
 		@JsonIgnore
 		@Adjacency(label="inport",direction = Direction.IN)
 		public Iterable<IFlowEntry> getInFlowEntries();
@@ -125,6 +126,7 @@
 		@Adjacency(label="outport",direction = Direction.IN)
 		public Iterable<IFlowEntry> getOutFlowEntries();
 		
+		
 		@JsonIgnore
 		@Adjacency(label="link")
 		public Iterable<IPortObject> getLinkedPorts();
diff --git a/src/main/java/net/onrc/onos/ofcontroller/core/internal/DeviceStorageImpl.java b/src/main/java/net/onrc/onos/ofcontroller/core/internal/DeviceStorageImpl.java
index 6ee3c46..182a20a 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/core/internal/DeviceStorageImpl.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/core/internal/DeviceStorageImpl.java
@@ -77,27 +77,34 @@
 	@Override
 	public IDeviceObject addDevice(IDevice device) {
 		IDeviceObject obj = null;
-		try {
-			if ((obj = ope.searchDevice(device.getMACAddressString())) != null) {
-				log.debug("Adding device {}: found existing device", device.getMACAddressString());
-			} else {
-				obj = ope.newDevice();
-				log.debug("Adding device {}: creating new device", device.getMACAddressString());
+		for (int i = 0; i < 6; i++) {
+	 		try {
+	 			if (i > 0) {
+	 				log.debug("Retrying add device: i is {}", i);
+	 			}
+	 			if ((obj = ope.searchDevice(device.getMACAddressString())) != null) {
+	 				log.debug("Adding device {}: found existing device", device.getMACAddressString());
+	            } else {
+	            	obj = ope.newDevice();
+	                log.debug("Adding device {}: creating new device", device.getMACAddressString());
+	            }
+	 			
+	            changeDeviceAttachments(device, obj);
+		        
+	            changeDeviceIpv4Addresses(device, obj);
+	            
+	 			obj.setMACAddress(device.getMACAddressString());
+	 			obj.setType("device");
+	 			obj.setState("ACTIVE");
+	 			ope.commit();
+	 			
+	 			break;
+	 			//log.debug("Adding device {}",device.getMACAddressString());
+			} catch (TitanException e) {
+				ope.rollback();
+				log.error("Adding device {} failed", device.getMACAddressString(), e);
+				obj = null;
 			}
-			changeDeviceAttachments(device, obj);
-
-			changeDeviceIpv4Addresses(device, obj);
-
- 			obj.setMACAddress(device.getMACAddressString());
- 			obj.setType("device");
- 			obj.setState("ACTIVE");
- 			ope.commit();
-		
- 			//log.debug("Adding device {}",device.getMACAddressString());
-		} catch (TitanException e) {
-			ope.rollback();
-			log.error("Adding device {} failed", device.getMACAddressString(), e);
-			obj = null;
 		}
  		
 		return obj;		
@@ -274,8 +281,10 @@
 	
 	private void changeDeviceIpv4Addresses(IDevice device, IDeviceObject deviceObject) {
 		List<String> dbIpv4Addresses = new ArrayList<String>();
+		List<Integer> intDbIpv4Addresses = new ArrayList<Integer>();
 		for (IIpv4Address ipv4Vertex : deviceObject.getIpv4Addresses()) {
 			dbIpv4Addresses.add(InetAddresses.fromInteger(ipv4Vertex.getIpv4Address()).getHostAddress());
+			intDbIpv4Addresses.add(ipv4Vertex.getIpv4Address());
 		}
 		
 		List<String> memIpv4Addresses = new ArrayList<String>();
@@ -287,13 +296,16 @@
 				memIpv4Addresses, dbIpv4Addresses);
 		
 		for (int ipv4Address : device.getIPv4Addresses()) {
-			if (deviceObject.getIpv4Address(ipv4Address) == null) {
+			//if (deviceObject.getIpv4Address(ipv4Address) == null) {
+			if (!intDbIpv4Addresses.contains(ipv4Address)) {
 				IIpv4Address dbIpv4Address = ope.ensureIpv4Address(ipv4Address);
 				
+				/*
 				IDeviceObject oldDevice = dbIpv4Address.getDevice();
 				if (oldDevice != null) {
 					oldDevice.removeIpv4Address(dbIpv4Address);
 				}
+				*/
 				
 				log.debug("Adding IP address {}", 
 						InetAddresses.fromInteger(ipv4Address).getHostAddress());
diff --git a/src/main/java/net/onrc/onos/ofcontroller/core/web/TopoSwitchesResource.java b/src/main/java/net/onrc/onos/ofcontroller/core/web/TopoSwitchesResource.java
index a173a70..6d3f161 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/core/web/TopoSwitchesResource.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/core/web/TopoSwitchesResource.java
@@ -17,12 +17,12 @@
 		String filter = (String) getRequestAttributes().get("filter");
 		
 		if (filter.equals("active")) {
-			return (Iterator<ISwitchObject>) impl.getActiveSwitches().iterator();
+			return impl.getActiveSwitches().iterator();
 		}
 		if (filter.equals("inactive")) {
-			return (Iterator<ISwitchObject>) impl.getInactiveSwitches().iterator();
+			return impl.getInactiveSwitches().iterator();
 		} else {
-		    return (Iterator<ISwitchObject>) impl.getAllSwitches().iterator();
+		    return impl.getAllSwitches().iterator();
 		}
 	}
 
diff --git a/src/main/java/net/onrc/onos/ofcontroller/floodlightlistener/NetworkGraphPublisher.java b/src/main/java/net/onrc/onos/ofcontroller/floodlightlistener/NetworkGraphPublisher.java
index c1dbe54..c94acd5 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/floodlightlistener/NetworkGraphPublisher.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/floodlightlistener/NetworkGraphPublisher.java
@@ -248,10 +248,13 @@
 			    // Publish: add the ports
 			    // TODO: Add only ports that are UP?
 			    for (OFPhysicalPort port : sw.getPorts()) {
-				TopologyElement topologyElementPort =
-				    new TopologyElement(sw.getId(),
-							port.getPortNumber());
-				datagridService.notificationSendTopologyElementAdded(topologyElementPort);
+					TopologyElement topologyElementPort =
+					    new TopologyElement(sw.getId(), port.getPortNumber());
+					datagridService.notificationSendTopologyElementAdded(topologyElementPort);
+					
+					// Allow links to be discovered on this port now that it's
+					// in the database
+					linkDiscovery.RemoveFromSuppressLLDPs(sw.getId(), port.getPortNumber());
 			    }
 
 			    // Add all links that might be connected already
@@ -320,6 +323,10 @@
 	@Override
 	public void switchPortAdded(Long switchId, OFPhysicalPort port) {
 		if (swStore.addPort(HexString.toHexString(switchId), port)) {
+			// Allow links to be discovered on this port now that it's
+			// in the database
+			linkDiscovery.RemoveFromSuppressLLDPs(switchId, port.getPortNumber());
+			
 		    // TODO publish ADD_PORT event here
 		    TopologyElement topologyElement =
 			new TopologyElement(switchId, port.getPortNumber());
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowDatabaseOperation.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowDatabaseOperation.java
index 1bea72d..da40bef 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowDatabaseOperation.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowDatabaseOperation.java
@@ -3,7 +3,6 @@
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.LinkedList;
 import java.util.List;
@@ -24,21 +23,17 @@
 /**
  * Class for performing Flow-related operations on the Database.
  */
-class FlowDatabaseOperation {
+public class FlowDatabaseOperation {
     private final static Logger log = LoggerFactory.getLogger(FlowDatabaseOperation.class);
 
     /**
      * Add a flow.
      *
-     * @param flowManager the Flow Manager to use.
      * @param dbHandler the Graph Database handler to use.
      * @param flowPath the Flow Path to install.
-     * @param flowId the return-by-reference Flow ID as assigned internally.
      * @return true on success, otherwise false.
      */
-    static boolean addFlow(FlowManager flowManager,
-			   DBOperation dbHandler,
-			   FlowPath flowPath, FlowId flowId) {
+    static boolean addFlow(DBOperation dbHandler, FlowPath flowPath) {
 	IFlowPath flowObj = null;
 	boolean found = false;
 	try {
@@ -68,6 +63,21 @@
 	}
 
 	//
+	// Remove the old Flow Entries
+	//
+	if (found) {
+	    Iterable<IFlowEntry> flowEntries = flowObj.getFlowEntries();
+	    LinkedList<IFlowEntry> deleteFlowEntries =
+		new LinkedList<IFlowEntry>();
+	    for (IFlowEntry flowEntryObj : flowEntries)
+		deleteFlowEntries.add(flowEntryObj);
+	    for (IFlowEntry flowEntryObj : deleteFlowEntries) {
+		flowObj.removeFlowEntry(flowEntryObj);
+		dbHandler.removeFlowEntry(flowEntryObj);
+	    }
+	}
+
+	//
 	// Set the Flow key:
 	// - flowId
 	//
@@ -155,45 +165,33 @@
 	// flowPath.dataPath().flowEntries()
 	//
 	for (FlowEntry flowEntry : flowPath.dataPath().flowEntries()) {
-	    if (addFlowEntry(flowManager, dbHandler, flowObj, flowEntry) == null) {
+	    if (flowEntry.flowEntryUserState() == FlowEntryUserState.FE_USER_DELETE)
+		continue;	// Skip: all Flow Entries were deleted earlier
+
+	    if (addFlowEntry(dbHandler, flowObj, flowEntry) == null) {
 		dbHandler.rollback();
 		return false;
 	    }
 	}
 	dbHandler.commit();
 
-	//
-	// TODO: We need a proper Flow ID allocation mechanism.
-	//
-	flowId.setValue(flowPath.flowId().value());
-
 	return true;
     }
 
     /**
      * Add a flow entry to the Network MAP.
      *
-     * @param flowManager the Flow Manager to use.
      * @param dbHandler the Graph Database handler to use.
      * @param flowObj the corresponding Flow Path object for the Flow Entry.
      * @param flowEntry the Flow Entry to install.
      * @return the added Flow Entry object on success, otherwise null.
      */
-    static IFlowEntry addFlowEntry(FlowManager flowManager,
-				   DBOperation dbHandler,
+    static IFlowEntry addFlowEntry(DBOperation dbHandler,
 				   IFlowPath flowObj,
 				   FlowEntry flowEntry) {
 	// Flow edges
 	//   HeadFE (TODO)
 
-	//
-	// Assign the FlowEntry ID.
-	//
-	if (! flowEntry.isValidFlowEntryId()) {
-	    long id = flowManager.getNextFlowEntryId();
-	    flowEntry.setFlowEntryId(new FlowEntryId(id));
-	}
-
 	IFlowEntry flowEntryObj = null;
 	boolean found = false;
 	try {
@@ -497,137 +495,6 @@
     }
 
     /**
-     * Get all previously added flows by a specific installer for a given
-     * data path endpoints.
-     *
-     * @param dbHandler the Graph Database handler to use.
-     * @param installerId the Caller ID of the installer of the flow to get.
-     * @param dataPathEndpoints the data path endpoints of the flow to get.
-     * @return the Flow Paths if found, otherwise null.
-     */
-    static ArrayList<FlowPath> getAllFlows(DBOperation dbHandler,
-					   CallerId installerId,
-					   DataPathEndpoints dataPathEndpoints) {
-	//
-	// TODO: The implementation below is not optimal:
-	// We fetch all flows, and then return only the subset that match
-	// the query conditions.
-	// We should use the appropriate Titan/Gremlin query to filter-out
-	// the flows as appropriate.
-	//
-	ArrayList<FlowPath> allFlows = getAllFlows(dbHandler);
-	ArrayList<FlowPath> flowPaths = new ArrayList<FlowPath>();
-
-	if (allFlows == null)
-	    return flowPaths;
-
-	for (FlowPath flow : allFlows) {
-	    //
-	    // TODO: String-based comparison is sub-optimal.
-	    // We are using it for now to save us the extra work of
-	    // implementing the "equals()" and "hashCode()" methods.
-	    //
-	    if (! flow.installerId().toString().equals(installerId.toString()))
-		continue;
-	    if (! flow.dataPath().srcPort().toString().equals(dataPathEndpoints.srcPort().toString())) {
-		continue;
-	    }
-	    if (! flow.dataPath().dstPort().toString().equals(dataPathEndpoints.dstPort().toString())) {
-		continue;
-	    }
-	    flowPaths.add(flow);
-	}
-
-	return flowPaths;
-    }
-
-    /**
-     * Get all installed flows by all installers for given data path endpoints.
-     *
-     * @param dbHandler the Graph Database handler to use.
-     * @param dataPathEndpoints the data path endpoints of the flows to get.
-     * @return the Flow Paths if found, otherwise null.
-     */
-    static ArrayList<FlowPath> getAllFlows(DBOperation dbHandler,
-					   DataPathEndpoints dataPathEndpoints) {
-	//
-	// TODO: The implementation below is not optimal:
-	// We fetch all flows, and then return only the subset that match
-	// the query conditions.
-	// We should use the appropriate Titan/Gremlin query to filter-out
-	// the flows as appropriate.
-	//
-	ArrayList<FlowPath> flowPaths = new ArrayList<FlowPath>();
-	ArrayList<FlowPath> allFlows = getAllFlows(dbHandler);
-
-	if (allFlows == null)
-	    return flowPaths;
-
-	for (FlowPath flow : allFlows) {
-	    //
-	    // TODO: String-based comparison is sub-optimal.
-	    // We are using it for now to save us the extra work of
-	    // implementing the "equals()" and "hashCode()" methods.
-	    //
-	    if (! flow.dataPath().srcPort().toString().equals(dataPathEndpoints.srcPort().toString())) {
-		continue;
-	    }
-	    if (! flow.dataPath().dstPort().toString().equals(dataPathEndpoints.dstPort().toString())) {
-		continue;
-	    }
-	    flowPaths.add(flow);
-	}
-
-	return flowPaths;
-    }
-
-    /**
-     * Get summary of all installed flows by all installers in a given range.
-     *
-     * @param dbHandler the Graph Database handler to use.
-     * @param flowId the Flow ID of the first flow in the flow range to get.
-     * @param maxFlows the maximum number of flows to be returned.
-     * @return the Flow Paths if found, otherwise null.
-     */
-    static ArrayList<FlowPath> getAllFlowsSummary(DBOperation dbHandler,
-						   FlowId flowId,
-						   int maxFlows) {
-	//
-	// TODO: The implementation below is not optimal:
-	// We fetch all flows, and then return only the subset that match
-	// the query conditions.
-	// We should use the appropriate Titan/Gremlin query to filter-out
-	// the flows as appropriate.
-	//
-    	ArrayList<FlowPath> flowPaths = getAllFlowsWithDataPathSummary(dbHandler);
-    	Collections.sort(flowPaths);
-    	return flowPaths;
-    }
-
-    /**
-     * Get all Flows information, with Data Path summary for the Flow Entries.
-     *
-     * @param dbHandler the Graph Database handler to use.
-     * @return all Flows information, with Data Path summary for the Flow
-     * Entries.
-     */
-    static ArrayList<FlowPath> getAllFlowsWithDataPathSummary(DBOperation dbHandler) {
-    	ArrayList<FlowPath> flowPaths = getAllFlows(dbHandler);
-
-	// Truncate each Flow Path and Flow Entry
-	for (FlowPath flowPath : flowPaths) {
-	    flowPath.setFlowEntryMatch(null);
-	    flowPath.setFlowEntryActions(null);
-	    for (FlowEntry flowEntry : flowPath.flowEntries()) {
-		flowEntry.setFlowEntryMatch(null);
-		flowEntry.setFlowEntryActions(null);
-	    }
-	}
-
-    	return flowPaths;
-    }
-
-    /**
      * Extract Flow Path State from a Titan Database Object @ref IFlowPath.
      *
      * @param flowObj the object to extract the Flow Path State from.
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowEventHandler.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowEventHandler.java
index eccf40b..6c200fa 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowEventHandler.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowEventHandler.java
@@ -7,6 +7,8 @@
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.SortedMap;
+import java.util.TreeMap;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
 
@@ -27,24 +29,14 @@
 import net.onrc.onos.ofcontroller.util.FlowId;
 import net.onrc.onos.ofcontroller.util.FlowPath;
 import net.onrc.onos.ofcontroller.util.FlowPathUserState;
+import net.onrc.onos.ofcontroller.util.serializers.KryoFactory;
+
+import com.esotericsoftware.kryo2.Kryo;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * A class for storing a pair of Flow Path and a Flow Entry.
- */
-class FlowPathEntryPair {
-    protected FlowPath flowPath;
-    protected FlowEntry flowEntry;
-
-    protected FlowPathEntryPair(FlowPath flowPath, FlowEntry flowEntry) {
-	this.flowPath = flowPath;
-	this.flowEntry = flowEntry;
-    }
-}
-
-/**
  * Class for FlowPath Maintenance.
  * This class listens for FlowEvents to:
  * - Maintain a local cache of the Network Topology.
@@ -58,9 +50,7 @@
     private FlowManager flowManager;		// The Flow Manager to use
     private IDatagridService datagridService;	// The Datagrid Service to use
     private Topology topology;			// The network topology
-    private Map<Long, FlowPath> allFlowPaths = new HashMap<Long, FlowPath>();
-    private Map<Long, FlowEntry> unmatchedFlowEntryAdd =
-	new HashMap<Long, FlowEntry>();
+    private KryoFactory kryoFactory = new KryoFactory();
 
     // The queue with Flow Path and Topology Element updates
     private BlockingQueue<EventEntry<?>> networkEvents =
@@ -74,21 +64,22 @@
     private List<EventEntry<FlowEntry>> flowEntryEvents =
 	new LinkedList<EventEntry<FlowEntry>>();
 
+    // All internally computed Flow Paths
+    private Map<Long, FlowPath> allFlowPaths = new HashMap<Long, FlowPath>();
+
+    // The Flow Entries received as notifications with unmatched Flow Paths
+    private Map<Long, FlowEntry> unmatchedFlowEntryAdd =
+	new HashMap<Long, FlowEntry>();
+
     //
     // Transient state for processing the Flow Paths:
-    //  - The new Flow Paths
     //  - The Flow Paths that should be recomputed
     //  - The Flow Paths with modified Flow Entries
-    //  - The Flow Entries that were updated
     //
-    private List<FlowPath> newFlowPaths = new LinkedList<FlowPath>();
-    private List<FlowPath> recomputeFlowPaths = new LinkedList<FlowPath>();
-    private List<FlowPath> modifiedFlowPaths = new LinkedList<FlowPath>();
-    private List<FlowPathEntryPair> updatedFlowEntries =
-	new LinkedList<FlowPathEntryPair>();
-    private List<FlowPathEntryPair> unmatchedDeleteFlowEntries =
-	new LinkedList<FlowPathEntryPair>();
-
+    private Map<Long, FlowPath> shouldRecomputeFlowPaths =
+	new HashMap<Long, FlowPath>();
+    private Map<Long, FlowPath> modifiedFlowPaths =
+	new HashMap<Long, FlowPath>();
 
     /**
      * Constructor for a given Flow Manager and Datagrid Service.
@@ -144,7 +135,9 @@
 	}
 
 	// Process the initial events (if any)
-	processEvents();
+	synchronized (allFlowPaths) {
+	    processEvents();
+	}
     }
 
     /**
@@ -198,7 +191,9 @@
 		collection.clear();
 
 		// Process the events (if any)
-		processEvents();
+		synchronized (allFlowPaths) {
+		    processEvents();
+		}
 	    }
 	} catch (Exception exception) {
 	    log.debug("Exception processing Network Events: ", exception);
@@ -209,7 +204,7 @@
      * Process the events (if any)
      */
     private void processEvents() {
-	List<FlowPathEntryPair> modifiedFlowEntries;
+	Collection<FlowEntry> modifiedFlowEntries;
 
 	if (topologyEvents.isEmpty() && flowPathEvents.isEmpty() &&
 	    flowEntryEvents.isEmpty()) {
@@ -218,40 +213,30 @@
 
 	processFlowPathEvents();
 	processTopologyEvents();
-	//
-	// Add all new Flows: should be done after processing the Flow Path
-	// and Topology events.
-	//
-	for (FlowPath flowPath : newFlowPaths) {
-	    allFlowPaths.put(flowPath.flowId().value(), flowPath);
-	}
-
 	processFlowEntryEvents();
 
 	// Recompute all affected Flow Paths and keep only the modified
-	for (FlowPath flowPath : recomputeFlowPaths) {
+	for (FlowPath flowPath : shouldRecomputeFlowPaths.values()) {
 	    if (recomputeFlowPath(flowPath))
-		modifiedFlowPaths.add(flowPath);
+		modifiedFlowPaths.put(flowPath.flowId().value(), flowPath);
 	}
 
-	modifiedFlowEntries = extractModifiedFlowEntries(modifiedFlowPaths);
+	// Extract the modified Flow Entries
+	modifiedFlowEntries = extractModifiedFlowEntries(modifiedFlowPaths.values());
 
 	// Assign missing Flow Entry IDs
 	assignFlowEntryId(modifiedFlowEntries);
 
 	//
-	// Push the modified Flow Entries to switches, datagrid and database
+	// Push the modified state to the Flow Manager
 	//
-	flowManager.pushModifiedFlowEntriesToSwitches(modifiedFlowEntries);
-	flowManager.pushModifiedFlowEntriesToDatagrid(modifiedFlowEntries);
-	flowManager.pushModifiedFlowEntriesToDatabase(modifiedFlowEntries);
-	flowManager.pushModifiedFlowEntriesToDatabase(updatedFlowEntries);
-	flowManager.pushModifiedFlowEntriesToDatabase(unmatchedDeleteFlowEntries);
+	flowManager.pushModifiedFlowState(modifiedFlowPaths.values(),
+					  modifiedFlowEntries);
 
 	//
 	// Remove Flow Entries that were deleted
 	//
-	for (FlowPath flowPath : modifiedFlowPaths)
+	for (FlowPath flowPath : modifiedFlowPaths.values())
 	    flowPath.dataPath().removeDeletedFlowEntries();
 
 	// Cleanup
@@ -259,29 +244,26 @@
 	flowPathEvents.clear();
 	flowEntryEvents.clear();
 	//
-	newFlowPaths.clear();
-	recomputeFlowPaths.clear();
+	shouldRecomputeFlowPaths.clear();
 	modifiedFlowPaths.clear();
-	updatedFlowEntries.clear();
-	unmatchedDeleteFlowEntries.clear();
     }
 
     /**
      * Extract the modified Flow Entries.
+     *
+     * @param modifiedFlowPaths the Flow Paths to process.
+     * @return a collection with the modified Flow Entries.
      */
-    private List<FlowPathEntryPair> extractModifiedFlowEntries(
-					List<FlowPath> modifiedFlowPaths) {
-	List<FlowPathEntryPair> modifiedFlowEntries =
-	    new LinkedList<FlowPathEntryPair>();
+    private Collection<FlowEntry> extractModifiedFlowEntries(
+			Collection<FlowPath> modifiedFlowPaths) {
+	List<FlowEntry> modifiedFlowEntries = new LinkedList<FlowEntry>();
 
 	// Extract only the modified Flow Entries
 	for (FlowPath flowPath : modifiedFlowPaths) {
 	    for (FlowEntry flowEntry : flowPath.flowEntries()) {
 		if (flowEntry.flowEntrySwitchState() ==
 		    FlowEntrySwitchState.FE_SWITCH_NOT_UPDATED) {
-		    FlowPathEntryPair flowPair =
-			new FlowPathEntryPair(flowPath, flowEntry);
-		    modifiedFlowEntries.add(flowPair);
+		    modifiedFlowEntries.add(flowEntry);
 		}
 	    }
 	}
@@ -290,8 +272,11 @@
 
     /**
      * Assign the Flow Entry ID as needed.
+     *
+     * @param modifiedFlowEnries the collection of Flow Entries that need
+     * Flow Entry ID assigned.
      */
-    private void assignFlowEntryId(List<FlowPathEntryPair> modifiedFlowEntries) {
+    private void assignFlowEntryId(Collection<FlowEntry> modifiedFlowEntries) {
 	if (modifiedFlowEntries.isEmpty())
 	    return;
 
@@ -300,9 +285,7 @@
 	//
 	// Assign the Flow Entry ID only for Flow Entries for my switches
 	//
-	for (FlowPathEntryPair flowPair : modifiedFlowEntries) {
-	    FlowEntry flowEntry = flowPair.flowEntry;
-	    // Update the Flow Entries only for my switches
+	for (FlowEntry flowEntry : modifiedFlowEntries) {
 	    IOFSwitch mySwitch = mySwitches.get(flowEntry.dpid().value());
 	    if (mySwitch == null)
 		continue;
@@ -334,10 +317,8 @@
 		if (allFlowPaths.get(flowPath.flowId().value()) != null) {
 		    //
 		    // TODO: What to do if the Flow Path already exists?
-		    // Remove and then re-add it, or merge the info?
-		    // For now, we don't have to do anything.
+		    // Fow now, we just re-add it.
 		    //
-		    break;
 		}
 
 		switch (flowPath.flowPathType()) {
@@ -347,7 +328,8 @@
 		    // we are going to recompute it anyway.
 		    //
 		    flowPath.flowEntries().clear();
-		    recomputeFlowPaths.add(flowPath);
+		    shouldRecomputeFlowPaths.put(flowPath.flowId().value(),
+						 flowPath);
 		    break;
 		case FP_TYPE_EXPLICIT_PATH:
 		    //
@@ -356,10 +338,10 @@
 		    for (FlowEntry flowEntry : flowPath.flowEntries()) {
 			flowEntry.setFlowEntrySwitchState(FlowEntrySwitchState.FE_SWITCH_NOT_UPDATED);
 		    }
-		    modifiedFlowPaths.add(flowPath);
+		    modifiedFlowPaths.put(flowPath.flowId().value(), flowPath);
 		    break;
 		}
-		newFlowPaths.add(flowPath);
+		allFlowPaths.put(flowPath.flowId().value(), flowPath);
 
 		break;
 	    }
@@ -382,8 +364,11 @@
 		    flowEntry.setFlowEntrySwitchState(FlowEntrySwitchState.FE_SWITCH_NOT_UPDATED);
 		}
 
-		allFlowPaths.remove(existingFlowPath.flowId().value());
-		modifiedFlowPaths.add(existingFlowPath);
+		// Remove the Flow Path from the internal state
+		Long key = existingFlowPath.flowId().value();
+		allFlowPaths.remove(key);
+		shouldRecomputeFlowPaths.remove(key);
+		modifiedFlowPaths.put(key, existingFlowPath);
 
 		break;
 	    }
@@ -416,7 +401,7 @@
 	}
 	if (isTopologyModified) {
 	    // TODO: For now, if the topology changes, we recompute all Flows
-	    recomputeFlowPaths.addAll(allFlowPaths.values());
+	    shouldRecomputeFlowPaths.putAll(allFlowPaths);
 	}
     }
 
@@ -424,7 +409,6 @@
      * Process the Flow Entry events.
      */
     private void processFlowEntryEvents() {
-	FlowPathEntryPair flowPair;
 	FlowPath flowPath;
 	FlowEntry updatedFlowEntry;
 
@@ -443,8 +427,7 @@
 					 flowEntry);
 		    continue;
 		}
-		flowPair = new FlowPathEntryPair(flowPath, updatedFlowEntry);
-		updatedFlowEntries.add(flowPair);
+		modifiedFlowPaths.put(flowPath.flowId().value(), flowPath);
 	    }
 	    unmatchedFlowEntryAdd = remainingUpdates;
 	}
@@ -480,16 +463,15 @@
 		    break;
 		}
 		// Add the updated entry to the list of updated Flow Entries
-		flowPair = new FlowPathEntryPair(flowPath, updatedFlowEntry);
-		updatedFlowEntries.add(flowPair);
+		modifiedFlowPaths.put(flowPath.flowId().value(), flowPath);
 		break;
 
 	    case ENTRY_REMOVE:
 		flowEntry.setFlowEntryUserState(FlowEntryUserState.FE_USER_DELETE);
 		if (unmatchedFlowEntryAdd.remove(flowEntry.flowEntryId().value()) != null) {
-		    continue;		// Match found
+		    continue;		// Removed previously unmatched entry
 		}
-						 
+
 		flowPath = allFlowPaths.get(flowEntry.flowId().value());
 		if (flowPath == null) {
 		    // Flow Path not found: ignore the update
@@ -497,13 +479,10 @@
 		}
 		updatedFlowEntry = updateFlowEntryRemove(flowPath, flowEntry);
 		if (updatedFlowEntry == null) {
-		    // Flow Entry not found: add to list of deleted entries
-		    flowPair = new FlowPathEntryPair(flowPath, flowEntry);
-		    unmatchedDeleteFlowEntries.add(flowPair);
+		    // Flow Entry not found: ignore it
 		    break;
 		}
-		flowPair = new FlowPathEntryPair(flowPath, updatedFlowEntry);
-		updatedFlowEntries.add(flowPair);
+		modifiedFlowPaths.put(flowPath.flowId().value(), flowPath);
 		break;
 	    }
 	}
@@ -883,4 +862,31 @@
 	    new EventEntry<TopologyElement>(EventEntry.Type.ENTRY_ADD, topologyElement);
 	networkEvents.add(eventEntry);
     }
+
+    /**
+     * Get a sorted copy of all Flow Paths.
+     *
+     * @return a sorted copy of all Flow Paths.
+     */
+    synchronized SortedMap<Long, FlowPath> getAllFlowPathsCopy() {
+	SortedMap<Long, FlowPath> sortedFlowPaths =
+	    new TreeMap<Long, FlowPath>();
+
+	//
+	// TODO: For now we use serialization/deserialization to create
+	// a copy of each Flow Path. In the future, we should use proper
+	// copy constructors.
+	//
+	Kryo kryo = kryoFactory.newKryo();
+	synchronized (allFlowPaths) {
+	    for (Map.Entry<Long, FlowPath> entry : allFlowPaths.entrySet()) {
+		FlowPath origFlowPath = entry.getValue();
+		FlowPath copyFlowPath = kryo.copy(origFlowPath);
+		sortedFlowPaths.put(entry.getKey(), copyFlowPath);
+	    }
+	}
+	kryoFactory.deleteKryo(kryo);
+
+	return sortedFlowPaths;
+    }
 }
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowManager.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowManager.java
index 9e1c1ec..a2b8728 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowManager.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowManager.java
@@ -4,8 +4,10 @@
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.Map;
 import java.util.Random;
+import java.util.SortedMap;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ScheduledExecutorService;
@@ -61,8 +63,8 @@
     private final static Logger log = LoggerFactory.getLogger(FlowManager.class);
 
     // The queue to write Flow Entries to the database
-    private BlockingQueue<FlowPathEntryPair> flowEntriesToDatabaseQueue =
-	new LinkedBlockingQueue<FlowPathEntryPair>();
+    private BlockingQueue<FlowPath> flowPathsToDatabaseQueue =
+	new LinkedBlockingQueue<FlowPath>();
     FlowDatabaseWriter flowDatabaseWriter;
 
     /**
@@ -200,7 +202,7 @@
 	// The thread to write to the database
 	//
 	flowDatabaseWriter = new FlowDatabaseWriter(this,
-						flowEntriesToDatabaseQueue);
+						flowPathsToDatabaseQueue);
 	flowDatabaseWriter.start();
 
 	//
@@ -218,11 +220,17 @@
      * Add a flow.
      *
      * @param flowPath the Flow Path to install.
-     * @param flowId the return-by-reference Flow ID as assigned internally.
-     * @return true on success, otherwise false.
+     * @return the Flow ID on success, otherwise null.
      */
     @Override
-    public boolean addFlow(FlowPath flowPath, FlowId flowId) {
+    public FlowId addFlow(FlowPath flowPath) {
+
+	// Allocate the Flow ID if necessary
+	if (! flowPath.isValidFlowId()) {
+	    long id = getNextFlowEntryId();
+	    flowPath.setFlowId(new FlowId(id));
+	}
+
 	//
 	// NOTE: We need to explicitly initialize some of the state,
 	// in case the application didn't do it.
@@ -236,38 +244,11 @@
 		flowEntry.setFlowId(new FlowId(flowPath.flowId().value()));
 	}
 
-	dbHandlerApi = GraphDBManager.getDBOperation("ramcloud", "/tmp/ramcloudconf");
-	if (FlowDatabaseOperation.addFlow(this, dbHandlerApi, flowPath, flowId)) {
+	if (FlowDatabaseOperation.addFlow(dbHandlerApi, flowPath)) {
 	    datagridService.notificationSendFlowAdded(flowPath);
-	    return true;
+	    return flowPath.flowId();
 	}
-	return false;
-    }
-
-    /**
-     * Add a flow entry to the Network MAP.
-     *
-     * @param flowObj the corresponding Flow Path object for the Flow Entry.
-     * @param flowEntry the Flow Entry to install.
-     * @return the added Flow Entry object on success, otherwise null.
-     */
-    private IFlowEntry addFlowEntry(IFlowPath flowObj, FlowEntry flowEntry) {
-	dbHandlerInner = GraphDBManager.getDBOperation("ramcloud", "/tmp/ramcloudconf");
-	return FlowDatabaseOperation.addFlowEntry(this, dbHandlerInner,
-						  flowObj, flowEntry);
-    }
-
-    /**
-     * Delete a flow entry from the Network MAP.
-     *
-     * @param flowObj the corresponding Flow Path object for the Flow Entry.
-     * @param flowEntry the Flow Entry to delete.
-     * @return true on success, otherwise false.
-     */
-    private boolean deleteFlowEntry(IFlowPath flowObj, FlowEntry flowEntry) {
-	dbHandlerInner = GraphDBManager.getDBOperation("ramcloud", "/tmp/ramcloudconf");
-	return FlowDatabaseOperation.deleteFlowEntry(dbHandlerInner,
-						     flowObj, flowEntry);
+	return null;
     }
 
     /**
@@ -325,35 +306,6 @@
     }
 
     /**
-     * Get all previously added flows by a specific installer for a given
-     * data path endpoints.
-     *
-     * @param installerId the Caller ID of the installer of the flow to get.
-     * @param dataPathEndpoints the data path endpoints of the flow to get.
-     * @return the Flow Paths if found, otherwise null.
-     */
-    @Override
-    public ArrayList<FlowPath> getAllFlows(CallerId installerId,
-					   DataPathEndpoints dataPathEndpoints) {
-	dbHandlerApi = GraphDBManager.getDBOperation("ramcloud", "/tmp/ramcloudconf");
-	return FlowDatabaseOperation.getAllFlows(dbHandlerApi, installerId,
-						 dataPathEndpoints);
-    }
-
-    /**
-     * Get all installed flows by all installers for given data path endpoints.
-     *
-     * @param dataPathEndpoints the data path endpoints of the flows to get.
-     * @return the Flow Paths if found, otherwise null.
-     */
-    @Override
-    public ArrayList<FlowPath> getAllFlows(DataPathEndpoints dataPathEndpoints) {
-	dbHandlerApi = GraphDBManager.getDBOperation("ramcloud", "/tmp/ramcloudconf");
-	return FlowDatabaseOperation.getAllFlows(dbHandlerApi,
-						 dataPathEndpoints);
-    }
-
-    /**
      * Get summary of all installed flows by all installers in a given range.
      *
      * @param flowId the Flow ID of the first flow in the flow range to get.
@@ -363,31 +315,28 @@
     @Override
     public ArrayList<FlowPath> getAllFlowsSummary(FlowId flowId,
 						  int maxFlows) {
-	return FlowDatabaseOperation.getAllFlowsSummary(dbHandlerApi, flowId,
-							maxFlows);
-    }
-    
-    /**
-     * Add and maintain a shortest-path flow.
-     *
-     * NOTE: The Flow Path argument does NOT contain flow entries.
-     *
-     * @param flowPath the Flow Path with the endpoints and the match
-     * conditions to install.
-     * @return the added shortest-path flow on success, otherwise null.
-     */
-    @Override
-    public FlowPath addAndMaintainShortestPathFlow(FlowPath flowPath) {
-	//
-	// Don't do the shortest path computation here.
-	// Instead, let the Flow reconciliation thread take care of it.
-	//
+    	ArrayList<FlowPath> flowPaths = new ArrayList<FlowPath>();
+	SortedMap<Long, FlowPath> sortedFlowPaths =
+	    flowEventHandler.getAllFlowPathsCopy();
 
-	FlowId flowId = new FlowId();
-	if (! addFlow(flowPath, flowId))
-	    return null;
+	//
+	// Truncate each Flow Path and Flow Entry
+	//
+	for (FlowPath flowPath : sortedFlowPaths.values()) {
+	    //
+	    // TODO: Add only the Flow Paths that have been successfully
+	    // installed.
+	    //
+	    flowPath.setFlowEntryMatch(null);
+	    flowPath.setFlowEntryActions(null);
+	    for (FlowEntry flowEntry : flowPath.flowEntries()) {
+		flowEntry.setFlowEntryMatch(null);
+		flowEntry.setFlowEntryActions(null);
+	    }
+	    flowPaths.add(flowPath);
+	}
 
-	return (flowPath);
+	return flowPaths;
     }
 
     /**
@@ -419,101 +368,35 @@
     }
 
     /**
-     * Push modified Flow Entries to switches.
+     * Inform the Flow Manager that a collection of Flow Entries have been
+     * pushed to a switch.
      *
-     * NOTE: Only the Flow Entries to switches controlled by this instance
-     * are pushed.
-     *
-     * @param modifiedFlowEntries the collection of modified Flow Entries.
+     * @param entries the collection of <IOFSwitch, FlowEntry> pairs
+     * that have been pushed.
      */
-    public void pushModifiedFlowEntriesToSwitches(
-			Collection<FlowPathEntryPair> modifiedFlowEntries) {
-	if (modifiedFlowEntries.isEmpty())
-	    return;
+    public void flowEntriesPushedToSwitch(
+		Collection<Pair<IOFSwitch, FlowEntry>> entries) {
 
-	Map<Long, IOFSwitch> mySwitches = getMySwitches();
-
-	for (FlowPathEntryPair flowPair : modifiedFlowEntries) {
-	    FlowPath flowPath = flowPair.flowPath;
-	    FlowEntry flowEntry = flowPair.flowEntry;
-
-	    IOFSwitch mySwitch = mySwitches.get(flowEntry.dpid().value());
-	    if (mySwitch == null)
-		continue;
-
-	    log.debug("Pushing Flow Entry To Switch: {}", flowEntry.toString());
+	//
+	// Process all entries
+	//
+	for (Pair<IOFSwitch, FlowEntry> entry : entries) {
+	    IOFSwitch sw = entry.first;
+	    FlowEntry flowEntry = entry.second;
 
 	    //
-	    // Push the Flow Entry into the switch
-	    //
-	    if (! pusher.add(mySwitch, flowPath, flowEntry)) {
-		String logMsg = "Cannot install Flow Entry " +
-		    flowEntry.flowEntryId() +
-		    " from Flow Path " + flowPath.flowId() +
-		    " on switch " + flowEntry.dpid();
-		log.error(logMsg);
-		continue;
-	    }
-
-	    //
-	    // NOTE: Here we assume that the switch has been
-	    // successfully updated.
+	    // Mark the Flow Entry that it has been pushed to the switch
 	    //
 	    flowEntry.setFlowEntrySwitchState(FlowEntrySwitchState.FE_SWITCH_UPDATED);
-	}
-    }
 
-    /**
-     * Push modified Flow Entries to the datagrid.
-     *
-     * @param modifiedFlowEntries the collection of modified Flow Entries.
-     */
-    public void pushModifiedFlowEntriesToDatagrid(
-			Collection<FlowPathEntryPair> modifiedFlowEntries) {
-	if (modifiedFlowEntries.isEmpty())
-	    return;
-
-	Map<Long, IOFSwitch> mySwitches = getMySwitches();
-
-	for (FlowPathEntryPair flowPair : modifiedFlowEntries) {
-	    FlowEntry flowEntry = flowPair.flowEntry;
-
-	    if (! flowEntry.isValidFlowEntryId())
-		continue;
-
-	    IOFSwitch mySwitch = mySwitches.get(flowEntry.dpid().value());
-
-	    //
-	    // TODO: For now Flow Entries are removed by all instances,
-	    // even if this Flow Entry is not for our switches.
-	    //
-	    // This is needed to handle the case a switch going down:
-	    // it has no Master controller instance, hence no
-	    // controller instance will cleanup its flow entries.
-	    // This is sub-optimal: we need to elect a controller
-	    // instance to handle the cleanup of such orphaned flow
-	    // entries.
-	    //
-	    if (mySwitch == null) {
-		if (flowEntry.flowEntryUserState() !=
-		    FlowEntryUserState.FE_USER_DELETE) {
-		    continue;
-		}
-	    }
-
-	    log.debug("Pushing Flow Entry To Datagrid: {}", flowEntry.toString());
 	    //
 	    // Write the Flow Entry to the Datagrid
 	    //
 	    switch (flowEntry.flowEntryUserState()) {
 	    case FE_USER_ADD:
-		if (mySwitch == null)
-		    break;	// Install only flow entries for my switches
 		datagridService.notificationSendFlowEntryAdded(flowEntry);
 		break;
 	    case FE_USER_MODIFY:
-		if (mySwitch == null)
-		    break;	// Install only flow entries for my switches
 		datagridService.notificationSendFlowEntryUpdated(flowEntry);
 		break;
 	    case FE_USER_DELETE:
@@ -524,11 +407,122 @@
     }
 
     /**
+     * Push modified Flow-related state as appropriate.
+     *
+     * @param modifiedFlowPaths the collection of modified Flow Paths.
+     * @param modifiedFlowEntries the collection of modified Flow Entries.
+     */
+    void pushModifiedFlowState(Collection<FlowPath> modifiedFlowPaths,
+			       Collection<FlowEntry> modifiedFlowEntries) {
+	//
+	// Push the modified Flow state:
+	//  - Flow Entries to switches and the datagrid
+	//  - Flow Paths to the database
+	//
+	pushModifiedFlowEntriesToSwitches(modifiedFlowEntries);
+	pushModifiedFlowPathsToDatabase(modifiedFlowPaths);
+	cleanupDeletedFlowEntriesFromDatagrid(modifiedFlowEntries);
+    }
+
+    /**
+     * Push modified Flow Entries to switches.
+     *
+     * NOTE: Only the Flow Entries to switches controlled by this instance
+     * are pushed.
+     *
+     * @param modifiedFlowEntries the collection of modified Flow Entries.
+     */
+    private void pushModifiedFlowEntriesToSwitches(
+			Collection<FlowEntry> modifiedFlowEntries) {
+	if (modifiedFlowEntries.isEmpty())
+	    return;
+
+	List<Pair<IOFSwitch, FlowEntry>> entries =
+	    new LinkedList<Pair<IOFSwitch, FlowEntry>>();
+
+	Map<Long, IOFSwitch> mySwitches = getMySwitches();
+
+	//
+	// Create a collection of my Flow Entries to push
+	//
+	for (FlowEntry flowEntry : modifiedFlowEntries) {
+	    IOFSwitch mySwitch = mySwitches.get(flowEntry.dpid().value());
+	    if (mySwitch == null)
+		continue;
+
+	    //
+	    // Assign Flow Entry IDs if missing.
+	    //
+	    // NOTE: This is an additional safeguard, in case the
+	    // mySwitches set has changed (after the Flow Entry IDs
+	    // assignments by the caller).
+	    //
+	    if (! flowEntry.isValidFlowEntryId()) {
+		long id = getNextFlowEntryId();
+		flowEntry.setFlowEntryId(new FlowEntryId(id));
+	    }
+
+	    log.debug("Pushing Flow Entry To Switch: {}", flowEntry.toString());
+	    entries.add(new Pair<IOFSwitch, FlowEntry>(mySwitch, flowEntry));
+	}
+
+	pusher.pushFlowEntries(entries);
+    }
+
+    /**
+     * Cleanup deleted Flow Entries from the datagrid.
+     *
+     * NOTE: We cleanup only the Flow Entries that are not for our switches.
+     * This is needed to handle the case a switch going down:
+     * It has no Master controller instance, hence no controller instance
+     * will cleanup its flow entries.
+     * This is sub-optimal: we need to elect a controller instance to handle
+     * the cleanup of such orphaned flow entries.
+     *
+     * @param modifiedFlowEntries the collection of modified Flow Entries.
+     */
+    private void cleanupDeletedFlowEntriesFromDatagrid(
+			Collection<FlowEntry> modifiedFlowEntries) {
+	if (modifiedFlowEntries.isEmpty())
+	    return;
+
+	Map<Long, IOFSwitch> mySwitches = getMySwitches();
+
+	for (FlowEntry flowEntry : modifiedFlowEntries) {
+	    //
+	    // Process only Flow Entries that should be deleted and have
+	    // a valid Flow Entry ID.
+	    //
+	    if (! flowEntry.isValidFlowEntryId())
+		continue;
+	    if (flowEntry.flowEntryUserState() !=
+		FlowEntryUserState.FE_USER_DELETE) {
+		continue;
+	    }
+
+	    //
+	    // NOTE: The deletion of Flow Entries for my switches is handled
+	    // elsewhere.
+	    //
+	    IOFSwitch mySwitch = mySwitches.get(flowEntry.dpid().value());
+	    if (mySwitch != null)
+		continue;
+
+	    log.debug("Pushing cleanup of Flow Entry To Datagrid: {}", flowEntry.toString());
+
+	    //
+	    // Write the Flow Entry to the Datagrid
+	    //
+	    datagridService.notificationSendFlowEntryRemoved(flowEntry.flowEntryId());
+	}
+    }
+
+    /**
      * Class to implement writing to the database in a separate thread.
      */
     class FlowDatabaseWriter extends Thread {
 	private FlowManager flowManager;
-	private BlockingQueue<FlowPathEntryPair> blockingQueue;
+	private BlockingQueue<FlowPath> blockingQueue;
 
 	/**
 	 * Constructor.
@@ -537,7 +531,7 @@
 	 * @param blockingQueue the blocking queue to use.
 	 */
 	FlowDatabaseWriter(FlowManager flowManager,
-			   BlockingQueue<FlowPathEntryPair> blockingQueue) {
+			   BlockingQueue<FlowPath> blockingQueue) {
 	    this.flowManager = flowManager;
 	    this.blockingQueue = blockingQueue;
 	}
@@ -550,14 +544,13 @@
 	    //
 	    // The main loop
 	    //
-	    Collection<FlowPathEntryPair> collection =
-		new LinkedList<FlowPathEntryPair>();
+	    Collection<FlowPath> collection = new LinkedList<FlowPath>();
 	    try {
 		while (true) {
-		    FlowPathEntryPair entryPair = blockingQueue.take();
-		    collection.add(entryPair);
+		    FlowPath flowPath = blockingQueue.take();
+		    collection.add(flowPath);
 		    blockingQueue.drainTo(collection);
-		    flowManager.writeModifiedFlowEntriesToDatabase(collection);
+		    flowManager.writeModifiedFlowPathsToDatabase(collection);
 		    collection.clear();
 		}
 	    } catch (Exception exception) {
@@ -567,46 +560,40 @@
     }
 
     /**
-     * Push Flow Entries to the Network MAP.
+     * Push Flow Paths to the Network MAP.
      *
-     * NOTE: The Flow Entries are pushed only on the instance responsible
-     * for the first switch. This is to avoid database errors when multiple
-     * instances are writing Flow Entries for the same Flow Path.
+     * NOTE: The complete Flow Paths are pushed only on the instance
+     * responsible for the first switch. This is to avoid database errors
+     * when multiple instances are writing Flow Entries for the same Flow Path.
      *
-     * @param modifiedFlowEntries the collection of Flow Entries to push.
+     * @param modifiedFlowPaths the collection of Flow Paths to push.
      */
-    void pushModifiedFlowEntriesToDatabase(
-		Collection<FlowPathEntryPair> modifiedFlowEntries) {
+    private void pushModifiedFlowPathsToDatabase(
+		Collection<FlowPath> modifiedFlowPaths) {
 	//
-	// We only add the Flow Entries to the Database Queue.
+	// We only add the Flow Paths to the Database Queue.
 	// The FlowDatabaseWriter thread is responsible for the actual writing.
 	//
-	flowEntriesToDatabaseQueue.addAll(modifiedFlowEntries);
+	flowPathsToDatabaseQueue.addAll(modifiedFlowPaths);
     }
 
     /**
-     * Write Flow Entries to the Network MAP.
+     * Write Flow Paths to the Network MAP.
      *
-     * NOTE: The Flow Entries are written only on the instance responsible
-     * for the first switch. This is to avoid database errors when multiple
-     * instances are writing Flow Entries for the same Flow Path.
+     * NOTE: The complete Flow Paths are pushed only on the instance
+     * responsible for the first switch. This is to avoid database errors
+     * when multiple instances are writing Flow Entries for the same Flow Path.
      *
-     * @param modifiedFlowEntries the collection of Flow Entries to write.
+     * @param modifiedFlowPaths the collection of Flow Paths to write.
      */
-    private void writeModifiedFlowEntriesToDatabase(
-		Collection<FlowPathEntryPair> modifiedFlowEntries) {
-	if (modifiedFlowEntries.isEmpty())
+    private void writeModifiedFlowPathsToDatabase(
+		Collection<FlowPath> modifiedFlowPaths) {
+	if (modifiedFlowPaths.isEmpty())
 	    return;
 
 	Map<Long, IOFSwitch> mySwitches = getMySwitches();
 
-	for (FlowPathEntryPair flowPair : modifiedFlowEntries) {
-	    FlowPath flowPath = flowPair.flowPath;
-	    FlowEntry flowEntry = flowPair.flowEntry;
-
-	    if (! flowEntry.isValidFlowEntryId())
-		continue;
-
+	for (FlowPath flowPath : modifiedFlowPaths) {
 	    //
 	    // Push the changes only on the instance responsible for the
 	    // first switch.
@@ -616,71 +603,57 @@
 	    if (mySrcSwitch == null)
 		continue;
 
-	    log.debug("Pushing Flow Entry To Database: {}", flowEntry.toString());
 	    //
-	    // Write the Flow Entry to the Network Map
+	    // Delete the Flow Path from the Network Map
 	    //
-	    // NOTE: We try a number of times, in case somehow some other
-	    // instances are writing at the same time.
-	    // Apparently, if other instances are writing at the same time
-	    // this will trigger an error.
-	    //
-	    for (int i = 0; i < 6; i++) {
+	    if (flowPath.flowPathUserState() ==
+		FlowPathUserState.FP_USER_DELETE) {
+		log.debug("Deleting Flow Path From Database: {}",
+			  flowPath.toString());
+
 		try {
-		    //
-		    // Find the Flow Path in the Network MAP.
-		    //
-		    // NOTE: The Flow Path might not be found if the Flow was
-		    // just removed by some other controller instance.
-		    //
-		    System.out.println("writeModifiedFlowEntriesToDatabase");
-		    dbHandlerInner = GraphDBManager.getDBOperation("ramcloud", "/tmp/ramcloudconf");
-		    IFlowPath flowObj =
-			dbHandlerInner.searchFlowPath(flowEntry.flowId());
-		    if (flowObj == null) {
-			String logMsg = "Cannot find Network MAP entry for Flow Path " + flowEntry.flowId();
-			log.error(logMsg);
-			break;
+		    if (! FlowDatabaseOperation.deleteFlow(
+					dbHandlerInner,
+					flowPath.flowId())) {
+			log.error("Cannot delete Flow Path {} from Network Map",
+				  flowPath.flowId());
 		    }
-
-		    // Write the Flow Entry
-		    switch (flowEntry.flowEntryUserState()) {
-		    case FE_USER_ADD:
-			// FALLTHROUGH
-		    case FE_USER_MODIFY:
-			if (addFlowEntry(flowObj, flowEntry) == null) {
-			    String logMsg = "Cannot write to Network MAP Flow Entry " +
-				flowEntry.flowEntryId() +
-				" from Flow Path " + flowEntry.flowId() +
-				" on switch " + flowEntry.dpid();
-			    log.error(logMsg);
-			}
-			break;
-		    case FE_USER_DELETE:
-			if (deleteFlowEntry(flowObj, flowEntry) == false) {
-			    String logMsg = "Cannot remove from Network MAP Flow Entry " +
-				flowEntry.flowEntryId() +
-				" from Flow Path " + flowEntry.flowId() +
-				" on switch " + flowEntry.dpid();
-			    log.error(logMsg);
-			}
-			break;
-		    }
-
-		    // Commit to the database
-		    dbHandlerInner.commit();
-		    break;	// Success
-
 		} catch (Exception e) {
-		    log.debug("Exception writing Flow Entry to Network MAP: ", e);
-		    dbHandlerInner.rollback();
-		    // Wait a bit (random value [1ms, 20ms] and try again
-		    int delay = 1 + randomGenerator.nextInt() % 20;
-		    try {
-			Thread.sleep(delay);
-		    } catch (Exception e0) {
-		    }
+		    log.error("Exception deleting Flow Path from Network MAP: {}", e);
 		}
+		continue;
+	    }
+
+	    //
+	    // Test whether all Flow Entries are valid
+	    //
+	    boolean allValid = true;
+	    for (FlowEntry flowEntry : flowPath.flowEntries()) {
+		if (flowEntry.flowEntryUserState() ==
+		    FlowEntryUserState.FE_USER_DELETE) {
+		    continue;
+		}
+		if (! flowEntry.isValidFlowEntryId()) {
+		    allValid = false;
+		    break;
+		}
+	    }
+	    if (! allValid)
+		continue;
+
+	    log.debug("Pushing Flow Path To Database: {}", flowPath.toString());
+
+	    //
+	    // Write the Flow Path to the Network Map
+	    //
+	    try {
+		if (! FlowDatabaseOperation.addFlow(dbHandlerInner, flowPath)) {
+		    String logMsg = "Cannot write to Network Map Flow Path " +
+			flowPath.flowId();
+		    log.error(logMsg);
+		}
+	    } catch (Exception e) {
+		log.error("Exception writing Flow Path to Network MAP: ", e);
 	    }
 	}
     }
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowSwitchOperation.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowSwitchOperation.java
deleted file mode 100644
index 8bed120..0000000
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/FlowSwitchOperation.java
+++ /dev/null
@@ -1,689 +0,0 @@
-package net.onrc.onos.ofcontroller.flowmanager;
-
-import java.io.IOException;
-import java.util.ArrayList;
-import java.util.List;
-
-import net.floodlightcontroller.core.IOFSwitch;
-import net.floodlightcontroller.util.MACAddress;
-import net.floodlightcontroller.util.OFMessageDamper;
-
-import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowEntry;
-import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowPath;
-import net.onrc.onos.ofcontroller.util.*;
-import net.onrc.onos.ofcontroller.util.FlowEntryAction.*;
-
-import org.openflow.protocol.OFFlowMod;
-import org.openflow.protocol.OFMatch;
-import org.openflow.protocol.OFPacketOut;
-import org.openflow.protocol.OFPort;
-import org.openflow.protocol.OFType;
-import org.openflow.protocol.action.*;
-import org.openflow.protocol.factory.BasicFactory;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-/**
- * Class for performing Flow-related operations on the Switch.
- */
-class FlowSwitchOperation {
-    private final static Logger log = LoggerFactory.getLogger(FlowSwitchOperation.class);
-    //
-    // TODO: Values copied from elsewhere (class LearningSwitch).
-    // The local copy should go away!
-    //
-    public static final short PRIORITY_DEFAULT = 100;
-    public static final short FLOWMOD_DEFAULT_IDLE_TIMEOUT = 0;	// infinity
-    public static final short FLOWMOD_DEFAULT_HARD_TIMEOUT = 0;	// infinite
-
-    // TODO add Pusher instance member
-    // 
-    
-    /**
-     * Install a Flow Entry on a switch.
-     *
-     * @param messageFactory the OpenFlow message factory to use.
-     * @param messageDamper the OpenFlow message damper to use.
-     * @param mySwitch the switch to install the Flow Entry into.
-     * @param flowObj the flow path object for the flow entry to install.
-     * @param flowEntryObj the flow entry object to install.
-     * @return true on success, otherwise false.
-     */
-    static boolean installFlowEntry(BasicFactory messageFactory,
-				    OFMessageDamper messageDamper,
-				    IOFSwitch mySwitch, IFlowPath flowObj,
-				    IFlowEntry flowEntryObj) {
-	String flowEntryIdStr = flowEntryObj.getFlowEntryId();
-	if (flowEntryIdStr == null)
-	    return false;
-	FlowEntryId flowEntryId = new FlowEntryId(flowEntryIdStr);
-	String userState = flowEntryObj.getUserState();
-	if (userState == null)
-	    return false;
-
-	//
-	// Create the Open Flow Flow Modification Entry to push
-	//
-	OFFlowMod fm = (OFFlowMod)messageFactory.getMessage(OFType.FLOW_MOD);
-	long cookie = flowEntryId.value();
-
-	short flowModCommand = OFFlowMod.OFPFC_ADD;
-	if (userState.equals("FE_USER_ADD")) {
-	    flowModCommand = OFFlowMod.OFPFC_ADD;
-	} else if (userState.equals("FE_USER_MODIFY")) {
-	    flowModCommand = OFFlowMod.OFPFC_MODIFY_STRICT;
-	} else if (userState.equals("FE_USER_DELETE")) {
-	    flowModCommand = OFFlowMod.OFPFC_DELETE_STRICT;
-	} else {
-	    // Unknown user state. Ignore the entry
-	    log.debug("Flow Entry ignored (FlowEntryId = {}): unknown user state {}",
-		      flowEntryId.toString(), userState);
-	    return false;
-	}
-
-	//
-	// Fetch the match conditions.
-	//
-	// NOTE: The Flow matching conditions common for all Flow Entries are
-	// used ONLY if a Flow Entry does NOT have the corresponding matching
-	// condition set.
-	//
-	OFMatch match = new OFMatch();
-	match.setWildcards(OFMatch.OFPFW_ALL);
-
-	// Match the Incoming Port
-	Short matchInPort = flowEntryObj.getMatchInPort();
-	if (matchInPort != null) {
-	    match.setInputPort(matchInPort);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_IN_PORT);
-	}
-
-	// Match the Source MAC address
-	String matchSrcMac = flowEntryObj.getMatchSrcMac();
-	if (matchSrcMac == null)
-	    matchSrcMac = flowObj.getMatchSrcMac();
-	if (matchSrcMac != null) {
-	    match.setDataLayerSource(matchSrcMac);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_SRC);
-	}
-
-	// Match the Destination MAC address
-	String matchDstMac = flowEntryObj.getMatchDstMac();
-	if (matchDstMac == null)
-	    matchDstMac = flowObj.getMatchDstMac();
-	if (matchDstMac != null) {
-	    match.setDataLayerDestination(matchDstMac);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_DST);
-	}
-
-	// Match the Ethernet Frame Type
-	Short matchEthernetFrameType = flowEntryObj.getMatchEthernetFrameType();
-	if (matchEthernetFrameType == null)
-	    matchEthernetFrameType = flowObj.getMatchEthernetFrameType();
-	if (matchEthernetFrameType != null) {
-	    match.setDataLayerType(matchEthernetFrameType);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_TYPE);
-	}
-
-	// Match the VLAN ID
-	Short matchVlanId = flowEntryObj.getMatchVlanId();
-	if (matchVlanId == null)
-	    matchVlanId = flowObj.getMatchVlanId();
-	if (matchVlanId != null) {
-	    match.setDataLayerVirtualLan(matchVlanId);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_VLAN);
-	}
-
-	// Match the VLAN priority
-	Byte matchVlanPriority = flowEntryObj.getMatchVlanPriority();
-	if (matchVlanPriority == null)
-	    matchVlanPriority = flowObj.getMatchVlanPriority();
-	if (matchVlanPriority != null) {
-	    match.setDataLayerVirtualLanPriorityCodePoint(matchVlanPriority);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_VLAN_PCP);
-	}
-
-	// Match the Source IPv4 Network prefix
-	String matchSrcIPv4Net = flowEntryObj.getMatchSrcIPv4Net();
-	if (matchSrcIPv4Net == null)
-	    matchSrcIPv4Net = flowObj.getMatchSrcIPv4Net();
-	if (matchSrcIPv4Net != null) {
-	    match.setFromCIDR(matchSrcIPv4Net, OFMatch.STR_NW_SRC);
-	}
-
-	// Natch the Destination IPv4 Network prefix
-	String matchDstIPv4Net = flowEntryObj.getMatchDstIPv4Net();
-	if (matchDstIPv4Net == null)
-	    matchDstIPv4Net = flowObj.getMatchDstIPv4Net();
-	if (matchDstIPv4Net != null) {
-	    match.setFromCIDR(matchDstIPv4Net, OFMatch.STR_NW_DST);
-	}
-
-	// Match the IP protocol
-	Byte matchIpProto = flowEntryObj.getMatchIpProto();
-	if (matchIpProto == null)
-	    matchIpProto = flowObj.getMatchIpProto();
-	if (matchIpProto != null) {
-	    match.setNetworkProtocol(matchIpProto);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_NW_PROTO);
-	}
-
-	// Match the IP ToS (DSCP field, 6 bits)
-	Byte matchIpToS = flowEntryObj.getMatchIpToS();
-	if (matchIpToS == null)
-	    matchIpToS = flowObj.getMatchIpToS();
-	if (matchIpToS != null) {
-	    match.setNetworkTypeOfService(matchIpToS);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_NW_TOS);
-	}
-
-	// Match the Source TCP/UDP port
-	Short matchSrcTcpUdpPort = flowEntryObj.getMatchSrcTcpUdpPort();
-	if (matchSrcTcpUdpPort == null)
-	    matchSrcTcpUdpPort = flowObj.getMatchSrcTcpUdpPort();
-	if (matchSrcTcpUdpPort != null) {
-	    match.setTransportSource(matchSrcTcpUdpPort);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_TP_SRC);
-	}
-
-	// Match the Destination TCP/UDP port
-	Short matchDstTcpUdpPort = flowEntryObj.getMatchDstTcpUdpPort();
-	if (matchDstTcpUdpPort == null)
-	    matchDstTcpUdpPort = flowObj.getMatchDstTcpUdpPort();
-	if (matchDstTcpUdpPort != null) {
-	    match.setTransportDestination(matchDstTcpUdpPort);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_TP_DST);
-	}
-
-	//
-	// Fetch the actions
-	//
-	Short actionOutputPort = null;
-	List<OFAction> openFlowActions = new ArrayList<OFAction>();
-	int actionsLen = 0;
-	FlowEntryActions flowEntryActions = null;
-	String actionsStr = flowEntryObj.getActions();
-	if (actionsStr != null)
-	    flowEntryActions = new FlowEntryActions(actionsStr);
-	else
-	    flowEntryActions = new FlowEntryActions();
-	for (FlowEntryAction action : flowEntryActions.actions()) {
-	    ActionOutput actionOutput = action.actionOutput();
-	    ActionSetVlanId actionSetVlanId = action.actionSetVlanId();
-	    ActionSetVlanPriority actionSetVlanPriority = action.actionSetVlanPriority();
-	    ActionStripVlan actionStripVlan = action.actionStripVlan();
-	    ActionSetEthernetAddr actionSetEthernetSrcAddr = action.actionSetEthernetSrcAddr();
-	    ActionSetEthernetAddr actionSetEthernetDstAddr = action.actionSetEthernetDstAddr();
-	    ActionSetIPv4Addr actionSetIPv4SrcAddr = action.actionSetIPv4SrcAddr();
-	    ActionSetIPv4Addr actionSetIPv4DstAddr = action.actionSetIPv4DstAddr();
-	    ActionSetIpToS actionSetIpToS = action.actionSetIpToS();
-	    ActionSetTcpUdpPort actionSetTcpUdpSrcPort = action.actionSetTcpUdpSrcPort();
-	    ActionSetTcpUdpPort actionSetTcpUdpDstPort = action.actionSetTcpUdpDstPort();
-	    ActionEnqueue actionEnqueue = action.actionEnqueue();
-
-	    if (actionOutput != null) {
-		actionOutputPort = actionOutput.port().value();
-		// XXX: The max length is hard-coded for now
-		OFActionOutput ofa =
-		    new OFActionOutput(actionOutput.port().value(),
-				       (short)0xffff);
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetVlanId != null) {
-		OFActionVirtualLanIdentifier ofa =
-		    new OFActionVirtualLanIdentifier(actionSetVlanId.vlanId());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetVlanPriority != null) {
-		OFActionVirtualLanPriorityCodePoint ofa =
-		    new OFActionVirtualLanPriorityCodePoint(actionSetVlanPriority.vlanPriority());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionStripVlan != null) {
-		if (actionStripVlan.stripVlan() == true) {
-		    OFActionStripVirtualLan ofa = new OFActionStripVirtualLan();
-		    openFlowActions.add(ofa);
-		    actionsLen += ofa.getLength();
-		}
-	    }
-
-	    if (actionSetEthernetSrcAddr != null) {
-		OFActionDataLayerSource ofa = 
-		    new OFActionDataLayerSource(actionSetEthernetSrcAddr.addr().toBytes());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetEthernetDstAddr != null) {
-		OFActionDataLayerDestination ofa =
-		    new OFActionDataLayerDestination(actionSetEthernetDstAddr.addr().toBytes());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetIPv4SrcAddr != null) {
-		OFActionNetworkLayerSource ofa =
-		    new OFActionNetworkLayerSource(actionSetIPv4SrcAddr.addr().value());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetIPv4DstAddr != null) {
-		OFActionNetworkLayerDestination ofa =
-		    new OFActionNetworkLayerDestination(actionSetIPv4DstAddr.addr().value());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetIpToS != null) {
-		OFActionNetworkTypeOfService ofa =
-		    new OFActionNetworkTypeOfService(actionSetIpToS.ipToS());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetTcpUdpSrcPort != null) {
-		OFActionTransportLayerSource ofa =
-		    new OFActionTransportLayerSource(actionSetTcpUdpSrcPort.port());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetTcpUdpDstPort != null) {
-		OFActionTransportLayerDestination ofa =
-		    new OFActionTransportLayerDestination(actionSetTcpUdpDstPort.port());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionEnqueue != null) {
-		OFActionEnqueue ofa =
-		    new OFActionEnqueue(actionEnqueue.port().value(),
-					actionEnqueue.queueId());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-	}
-
-	fm.setIdleTimeout(FLOWMOD_DEFAULT_IDLE_TIMEOUT)
-	    .setHardTimeout(FLOWMOD_DEFAULT_HARD_TIMEOUT)
-	    .setPriority(PRIORITY_DEFAULT)
-	    .setBufferId(OFPacketOut.BUFFER_ID_NONE)
-	    .setCookie(cookie)
-	    .setCommand(flowModCommand)
-	    .setMatch(match)
-	    .setActions(openFlowActions)
-	    .setLengthU(OFFlowMod.MINIMUM_LENGTH + actionsLen);
-	fm.setOutPort(OFPort.OFPP_NONE.getValue());
-	if ((flowModCommand == OFFlowMod.OFPFC_DELETE) ||
-	    (flowModCommand == OFFlowMod.OFPFC_DELETE_STRICT)) {
-	    if (actionOutputPort != null)
-		fm.setOutPort(actionOutputPort);
-	}
-
-	//
-	// TODO: Set the following flag
-	// fm.setFlags(OFFlowMod.OFPFF_SEND_FLOW_REM);
-	// See method ForwardingBase::pushRoute()
-	//
-
-	//
-	// Write the message to the switch
-	//
-	log.debug("MEASUREMENT: Installing flow entry " + userState +
-		  " into switch DPID: " +
-		  mySwitch.getStringId() +
-		  " flowEntryId: " + flowEntryId.toString() +
-		  " srcMac: " + matchSrcMac + " dstMac: " + matchDstMac +
-		  " inPort: " + matchInPort + " outPort: " + actionOutputPort
-		  );
-	try {
-	    messageDamper.write(mySwitch, fm, null);
-	    mySwitch.flush();
-	    //
-	    // TODO: We should use the OpenFlow Barrier mechanism
-	    // to check for errors, and update the SwitchState
-	    // for a flow entry after the Barrier message is
-	    // is received.
-	    //
-	    flowEntryObj.setSwitchState("FE_SWITCH_UPDATED");
-	} catch (IOException e) {
-	    log.error("Failure writing flow mod from network map", e);
-	    return false;
-	}
-
-	return true;
-    }
-
-    /**
-     * Install a Flow Entry on a switch.
-     *
-     * @param messageFactory the OpenFlow message factory to use.
-     * @maram messageDamper the OpenFlow message damper to use.
-     * @param mySwitch the switch to install the Flow Entry into.
-     * @param flowPath the flow path for the flow entry to install.
-     * @param flowEntry the flow entry to install.
-     * @return true on success, otherwise false.
-     */
-    static boolean installFlowEntry(BasicFactory messageFactory,
-				    OFMessageDamper messageDamper,
-				    IOFSwitch mySwitch, FlowPath flowPath,
-				    FlowEntry flowEntry) {
-	//
-	// Create the OpenFlow Flow Modification Entry to push
-	//
-	OFFlowMod fm = (OFFlowMod)messageFactory.getMessage(OFType.FLOW_MOD);
-	long cookie = flowEntry.flowEntryId().value();
-
-	short flowModCommand = OFFlowMod.OFPFC_ADD;
-	if (flowEntry.flowEntryUserState() == FlowEntryUserState.FE_USER_ADD) {
-	    flowModCommand = OFFlowMod.OFPFC_ADD;
-	} else if (flowEntry.flowEntryUserState() == FlowEntryUserState.FE_USER_MODIFY) {
-	    flowModCommand = OFFlowMod.OFPFC_MODIFY_STRICT;
-	} else if (flowEntry.flowEntryUserState() == FlowEntryUserState.FE_USER_DELETE) {
-	    flowModCommand = OFFlowMod.OFPFC_DELETE_STRICT;
-	} else {
-	    // Unknown user state. Ignore the entry
-	    log.debug("Flow Entry ignored (FlowEntryId = {}): unknown user state {}",
-		      flowEntry.flowEntryId().toString(),
-		      flowEntry.flowEntryUserState());
-	    return false;
-	}
-
-	//
-	// Fetch the match conditions.
-	//
-	// NOTE: The Flow matching conditions common for all Flow Entries are
-	// used ONLY if a Flow Entry does NOT have the corresponding matching
-	// condition set.
-	//
-	OFMatch match = new OFMatch();
-	match.setWildcards(OFMatch.OFPFW_ALL);
-	FlowEntryMatch flowPathMatch = flowPath.flowEntryMatch();
-	FlowEntryMatch flowEntryMatch = flowEntry.flowEntryMatch();
-
-	// Match the Incoming Port
-	Port matchInPort = flowEntryMatch.inPort();
-	if (matchInPort != null) {
-	    match.setInputPort(matchInPort.value());
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_IN_PORT);
-	}
-
-	// Match the Source MAC address
-	MACAddress matchSrcMac = flowEntryMatch.srcMac();
-	if ((matchSrcMac == null) && (flowPathMatch != null)) {
-	    matchSrcMac = flowPathMatch.srcMac();
-	}
-	if (matchSrcMac != null) {
-	    match.setDataLayerSource(matchSrcMac.toString());
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_SRC);
-	}
-
-	// Match the Destination MAC address
-	MACAddress matchDstMac = flowEntryMatch.dstMac();
-	if ((matchDstMac == null) && (flowPathMatch != null)) {
-	    matchDstMac = flowPathMatch.dstMac();
-	}
-	if (matchDstMac != null) {
-	    match.setDataLayerDestination(matchDstMac.toString());
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_DST);
-	}
-
-	// Match the Ethernet Frame Type
-	Short matchEthernetFrameType = flowEntryMatch.ethernetFrameType();
-	if ((matchEthernetFrameType == null) && (flowPathMatch != null)) {
-	    matchEthernetFrameType = flowPathMatch.ethernetFrameType();
-	}
-	if (matchEthernetFrameType != null) {
-	    match.setDataLayerType(matchEthernetFrameType);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_TYPE);
-	}
-
-	// Match the VLAN ID
-	Short matchVlanId = flowEntryMatch.vlanId();
-	if ((matchVlanId == null) && (flowPathMatch != null)) {
-	    matchVlanId = flowPathMatch.vlanId();
-	}
-	if (matchVlanId != null) {
-	    match.setDataLayerVirtualLan(matchVlanId);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_VLAN);
-	}
-
-	// Match the VLAN priority
-	Byte matchVlanPriority = flowEntryMatch.vlanPriority();
-	if ((matchVlanPriority == null) && (flowPathMatch != null)) {
-	    matchVlanPriority = flowPathMatch.vlanPriority();
-	}
-	if (matchVlanPriority != null) {
-	    match.setDataLayerVirtualLanPriorityCodePoint(matchVlanPriority);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_VLAN_PCP);
-	}
-
-	// Match the Source IPv4 Network prefix
-	IPv4Net matchSrcIPv4Net = flowEntryMatch.srcIPv4Net();
-	if ((matchSrcIPv4Net == null) && (flowPathMatch != null)) {
-	    matchSrcIPv4Net = flowPathMatch.srcIPv4Net();
-	}
-	if (matchSrcIPv4Net != null) {
-	    match.setFromCIDR(matchSrcIPv4Net.toString(), OFMatch.STR_NW_SRC);
-	}
-
-	// Natch the Destination IPv4 Network prefix
-	IPv4Net matchDstIPv4Net = flowEntryMatch.dstIPv4Net();
-	if ((matchDstIPv4Net == null) && (flowPathMatch != null)) {
-	    matchDstIPv4Net = flowPathMatch.dstIPv4Net();
-	}
-	if (matchDstIPv4Net != null) {
-	    match.setFromCIDR(matchDstIPv4Net.toString(), OFMatch.STR_NW_DST);
-	}
-
-	// Match the IP protocol
-	Byte matchIpProto = flowEntryMatch.ipProto();
-	if ((matchIpProto == null) && (flowPathMatch != null)) {
-	    matchIpProto = flowPathMatch.ipProto();
-	}
-	if (matchIpProto != null) {
-	    match.setNetworkProtocol(matchIpProto);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_NW_PROTO);
-	}
-
-	// Match the IP ToS (DSCP field, 6 bits)
-	Byte matchIpToS = flowEntryMatch.ipToS();
-	if ((matchIpToS == null) && (flowPathMatch != null)) {
-	    matchIpToS = flowPathMatch.ipToS();
-	}
-	if (matchIpToS != null) {
-	    match.setNetworkTypeOfService(matchIpToS);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_NW_TOS);
-	}
-
-	// Match the Source TCP/UDP port
-	Short matchSrcTcpUdpPort = flowEntryMatch.srcTcpUdpPort();
-	if ((matchSrcTcpUdpPort == null) && (flowPathMatch != null)) {
-	    matchSrcTcpUdpPort = flowPathMatch.srcTcpUdpPort();
-	}
-	if (matchSrcTcpUdpPort != null) {
-	    match.setTransportSource(matchSrcTcpUdpPort);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_TP_SRC);
-	}
-
-	// Match the Destination TCP/UDP port
-	Short matchDstTcpUdpPort = flowEntryMatch.dstTcpUdpPort();
-	if ((matchDstTcpUdpPort == null) && (flowPathMatch != null)) {
-	    matchDstTcpUdpPort = flowPathMatch.dstTcpUdpPort();
-	}
-	if (matchDstTcpUdpPort != null) {
-	    match.setTransportDestination(matchDstTcpUdpPort);
-	    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_TP_DST);
-	}
-
-	//
-	// Fetch the actions
-	//
-	Short actionOutputPort = null;
-	List<OFAction> openFlowActions = new ArrayList<OFAction>();
-	int actionsLen = 0;
-	FlowEntryActions flowEntryActions = flowEntry.flowEntryActions();
-	//
-	for (FlowEntryAction action : flowEntryActions.actions()) {
-	    ActionOutput actionOutput = action.actionOutput();
-	    ActionSetVlanId actionSetVlanId = action.actionSetVlanId();
-	    ActionSetVlanPriority actionSetVlanPriority = action.actionSetVlanPriority();
-	    ActionStripVlan actionStripVlan = action.actionStripVlan();
-	    ActionSetEthernetAddr actionSetEthernetSrcAddr = action.actionSetEthernetSrcAddr();
-	    ActionSetEthernetAddr actionSetEthernetDstAddr = action.actionSetEthernetDstAddr();
-	    ActionSetIPv4Addr actionSetIPv4SrcAddr = action.actionSetIPv4SrcAddr();
-	    ActionSetIPv4Addr actionSetIPv4DstAddr = action.actionSetIPv4DstAddr();
-	    ActionSetIpToS actionSetIpToS = action.actionSetIpToS();
-	    ActionSetTcpUdpPort actionSetTcpUdpSrcPort = action.actionSetTcpUdpSrcPort();
-	    ActionSetTcpUdpPort actionSetTcpUdpDstPort = action.actionSetTcpUdpDstPort();
-	    ActionEnqueue actionEnqueue = action.actionEnqueue();
-
-	    if (actionOutput != null) {
-		actionOutputPort = actionOutput.port().value();
-		// XXX: The max length is hard-coded for now
-		OFActionOutput ofa =
-		    new OFActionOutput(actionOutput.port().value(),
-				       (short)0xffff);
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetVlanId != null) {
-		OFActionVirtualLanIdentifier ofa =
-		    new OFActionVirtualLanIdentifier(actionSetVlanId.vlanId());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetVlanPriority != null) {
-		OFActionVirtualLanPriorityCodePoint ofa =
-		    new OFActionVirtualLanPriorityCodePoint(actionSetVlanPriority.vlanPriority());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionStripVlan != null) {
-		if (actionStripVlan.stripVlan() == true) {
-		    OFActionStripVirtualLan ofa = new OFActionStripVirtualLan();
-		    openFlowActions.add(ofa);
-		    actionsLen += ofa.getLength();
-		}
-	    }
-
-	    if (actionSetEthernetSrcAddr != null) {
-		OFActionDataLayerSource ofa = 
-		    new OFActionDataLayerSource(actionSetEthernetSrcAddr.addr().toBytes());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetEthernetDstAddr != null) {
-		OFActionDataLayerDestination ofa =
-		    new OFActionDataLayerDestination(actionSetEthernetDstAddr.addr().toBytes());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetIPv4SrcAddr != null) {
-		OFActionNetworkLayerSource ofa =
-		    new OFActionNetworkLayerSource(actionSetIPv4SrcAddr.addr().value());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetIPv4DstAddr != null) {
-		OFActionNetworkLayerDestination ofa =
-		    new OFActionNetworkLayerDestination(actionSetIPv4DstAddr.addr().value());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetIpToS != null) {
-		OFActionNetworkTypeOfService ofa =
-		    new OFActionNetworkTypeOfService(actionSetIpToS.ipToS());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetTcpUdpSrcPort != null) {
-		OFActionTransportLayerSource ofa =
-		    new OFActionTransportLayerSource(actionSetTcpUdpSrcPort.port());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionSetTcpUdpDstPort != null) {
-		OFActionTransportLayerDestination ofa =
-		    new OFActionTransportLayerDestination(actionSetTcpUdpDstPort.port());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-
-	    if (actionEnqueue != null) {
-		OFActionEnqueue ofa =
-		    new OFActionEnqueue(actionEnqueue.port().value(),
-					actionEnqueue.queueId());
-		openFlowActions.add(ofa);
-		actionsLen += ofa.getLength();
-	    }
-	}
-
-	fm.setIdleTimeout(FLOWMOD_DEFAULT_IDLE_TIMEOUT)
-	    .setHardTimeout(FLOWMOD_DEFAULT_HARD_TIMEOUT)
-	    .setPriority(PRIORITY_DEFAULT)
-	    .setBufferId(OFPacketOut.BUFFER_ID_NONE)
-	    .setCookie(cookie)
-	    .setCommand(flowModCommand)
-	    .setMatch(match)
-	    .setActions(openFlowActions)
-	    .setLengthU(OFFlowMod.MINIMUM_LENGTH + actionsLen);
-	fm.setOutPort(OFPort.OFPP_NONE.getValue());
-	if ((flowModCommand == OFFlowMod.OFPFC_DELETE) ||
-	    (flowModCommand == OFFlowMod.OFPFC_DELETE_STRICT)) {
-	    if (actionOutputPort != null)
-		fm.setOutPort(actionOutputPort);
-	}
-
-	//
-	// TODO: Set the following flag
-	// fm.setFlags(OFFlowMod.OFPFF_SEND_FLOW_REM);
-	// See method ForwardingBase::pushRoute()
-	//
-
-	//
-	// Write the message to the switch
-	//
-	log.debug("MEASUREMENT: Installing flow entry " +
-		  flowEntry.flowEntryUserState() +
-		  " into switch DPID: " +
-		  mySwitch.getStringId() +
-		  " flowEntryId: " + flowEntry.flowEntryId().toString() +
-		  " srcMac: " + matchSrcMac + " dstMac: " + matchDstMac +
-		  " inPort: " + matchInPort + " outPort: " + actionOutputPort
-		  );
-	try {
-	    messageDamper.write(mySwitch, fm, null);
-	    mySwitch.flush();
-	    //
-	    // TODO: We should use the OpenFlow Barrier mechanism
-	    // to check for errors, and update the SwitchState
-	    // for a flow entry after the Barrier message is
-	    // is received.
-	    //
-	    // TODO: The FlowEntry Object in Titan should be set
-	    // to FE_SWITCH_UPDATED.
-	    //
-	} catch (IOException e) {
-	    log.error("Failure writing flow mod from network map", e);
-	    return false;
-	}
-	return true;
-    }
-}
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/IFlowService.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/IFlowService.java
index 8d2b797..a25602d 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/IFlowService.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/IFlowService.java
@@ -1,15 +1,18 @@
 package net.onrc.onos.ofcontroller.flowmanager;
 
 import java.util.ArrayList;
+import java.util.Collection;
 
 import net.floodlightcontroller.core.IOFSwitch;
 import net.floodlightcontroller.core.module.IFloodlightService;
 import net.onrc.onos.ofcontroller.topology.Topology;
 import net.onrc.onos.ofcontroller.util.CallerId;
 import net.onrc.onos.ofcontroller.util.DataPathEndpoints;
+import net.onrc.onos.ofcontroller.util.FlowEntry;
 import net.onrc.onos.ofcontroller.util.FlowEntryId;
 import net.onrc.onos.ofcontroller.util.FlowId;
 import net.onrc.onos.ofcontroller.util.FlowPath;
+import net.onrc.onos.ofcontroller.util.Pair;
 
 /**
  * Interface for providing Flow Service to other modules.
@@ -18,14 +21,10 @@
     /**
      * Add a flow.
      *
-     * Internally, ONOS will automatically register the installer for
-     * receiving Flow Path Notifications for that path.
-     *
      * @param flowPath the Flow Path to install.
-     * @param flowId the return-by-reference Flow ID as assigned internally.
-     * @return true on success, otherwise false.
+     * @return the Flow ID on success, otherwise null.
      */
-    boolean addFlow(FlowPath flowPath, FlowId flowId);
+    FlowId addFlow(FlowPath flowPath);
 
     /**
      * Delete all previously added flows.
@@ -58,25 +57,6 @@
     ArrayList<FlowPath> getAllFlows();
 
     /**
-     * Get all previously added flows by a specific installer for a given
-     * data path endpoints.
-     *
-     * @param installerId the Caller ID of the installer of the flow to get.
-     * @param dataPathEndpoints the data path endpoints of the flow to get.
-     * @return the Flow Paths if found, otherwise null.
-     */
-    ArrayList<FlowPath> getAllFlows(CallerId installerId,
-				 DataPathEndpoints dataPathEndpoints);
-
-    /**
-     * Get all installed flows by all installers for given data path endpoints.
-     *
-     * @param dataPathEndpoints the data path endpoints of the flows to get.
-     * @return the Flow Paths if found, otherwise null.
-     */
-    ArrayList<FlowPath> getAllFlows(DataPathEndpoints dataPathEndpoints);
-
-    /**
      * Get summary of all installed flows by all installers.
      *
      * @param flowId starting flow Id of the range
@@ -84,21 +64,6 @@
      * @return the Flow Paths if found, otherwise null.
      */
     ArrayList<FlowPath> getAllFlowsSummary(FlowId flowId, int maxFlows);
-    
-    /**
-     * Add and maintain a shortest-path flow.
-     *
-     * NOTE: The Flow Path argument does NOT contain all flow entries.
-     * Instead, it contains a single dummy flow entry that is used to
-     * store the matching condition(s).
-     * That entry is replaced by the appropriate entries from the
-     * internally performed shortest-path computation.
-     *
-     * @param flowPath the Flow Path with the endpoints and the match
-     * conditions to install.
-     * @return the added shortest-path flow on success, otherwise null.
-     */
-    FlowPath addAndMaintainShortestPathFlow(FlowPath flowPath);
 
     /**
      * Get the network topology.
@@ -106,7 +71,7 @@
      * @return the network topology.
      */
     Topology getTopology();
-    
+
     /**
      * Get a globally unique flow ID from the flow service.
      * NOTE: Not currently guaranteed to be globally unique.
@@ -122,4 +87,14 @@
      * @param flowEntryId the Flow Entry ID of the expired Flow Entry.
      */
     public void flowEntryOnSwitchExpired(IOFSwitch sw, FlowEntryId flowEntryId);
+
+    /**
+     * Inform the Flow Manager that a collection of Flow Entries have been
+     * pushed to a switch.
+     *
+     * @param entries the collection of <IOFSwitch, FlowEntry> pairs
+     * that have been pushed.
+     */
+    public void flowEntriesPushedToSwitch(
+			Collection<Pair<IOFSwitch, FlowEntry>> entries);
 }
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/AddFlowResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/AddFlowResource.java
index 0926f91..9afaaec 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/AddFlowResource.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/AddFlowResource.java
@@ -64,9 +64,9 @@
 
 	// Process the request
 	if (flowPath != null) {
-	    if (flowService.addFlow(flowPath, result) != true) {
-		result = new FlowId();		// Error: Return empty Flow Id
-	    }
+	    FlowId addedFlowId = flowService.addFlow(flowPath);
+	    if (addedFlowId != null)
+		result = addedFlowId;
 	}
 
         return result;
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/AddShortestPathFlowResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/AddShortestPathFlowResource.java
index 7a4e88c..4d03623 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/AddShortestPathFlowResource.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/AddShortestPathFlowResource.java
@@ -64,13 +64,9 @@
 
 	// Process the request
 	if (flowPath != null) {
-	    FlowPath addedFlowPath =
-		flowService.addAndMaintainShortestPathFlow(flowPath);
-	    if (addedFlowPath == null) {
-		result = new FlowId();		// Error: Return empty Flow Id
-	    } else {
-		result = addedFlowPath.flowId();
-	    }
+	    FlowId addedFlowId = flowService.addFlow(flowPath);
+	    if (addedFlowId != null)
+		result = addedFlowId;
 	}
 
         return result;
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/FlowWebRoutable.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/FlowWebRoutable.java
index 81d26dd..c358263 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/FlowWebRoutable.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/FlowWebRoutable.java
@@ -20,8 +20,6 @@
         router.attach("/add-shortest-path/json", AddShortestPathFlowResource.class);
         router.attach("/delete/{flow-id}/json", DeleteFlowResource.class);
         router.attach("/get/{flow-id}/json", GetFlowByIdResource.class);
-        router.attach("/getall-by-installer-id/{installer-id}/{src-dpid}/{src-port}/{dst-dpid}/{dst-port}/json", GetAllFlowsByInstallerIdResource.class);
-        router.attach("/getall-by-endpoints/{src-dpid}/{src-port}/{dst-dpid}/{dst-port}/json", GetAllFlowsByEndpointsResource.class);
         router.attach("/getall/json", GetAllFlowsResource.class);
         router.attach("/getsummary/{flow-id}/{max-flows}/json", GetSummaryFlowsResource.class);
         return router;
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/GetAllFlowsByEndpointsResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/GetAllFlowsByEndpointsResource.java
deleted file mode 100644
index 1ac98c0..0000000
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/GetAllFlowsByEndpointsResource.java
+++ /dev/null
@@ -1,75 +0,0 @@
-package net.onrc.onos.ofcontroller.flowmanager.web;
-
-import java.util.ArrayList;
-
-import net.onrc.onos.ofcontroller.flowmanager.IFlowService;
-import net.onrc.onos.ofcontroller.util.DataPathEndpoints;
-import net.onrc.onos.ofcontroller.util.Dpid;
-import net.onrc.onos.ofcontroller.util.FlowPath;
-import net.onrc.onos.ofcontroller.util.Port;
-import net.onrc.onos.ofcontroller.util.SwitchPort;
-
-import org.restlet.resource.Get;
-import org.restlet.resource.ServerResource;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-/**
- * Flow Manager REST API implementation: Get all Flow state for given
- * source and destination switches and ports.
- *
- * The "{src-dpid}" request attribute value is the source DPID of the flows to
- * get.
- * The "{src-port}" request attribute value is the source port of the flows to
- * get.
- * The "{dst-dpid}" request attribute value is the destination DPID of the
- * flows to get.
- * The "{dst-port}" request attribute value is the destination port of the
- * flows to get.
- *
- *   GET /wm/flow/getall-by-endpoints/{src-dpid}/{src-port}/{dst-dpid}/{dst-port}/json"
- */
-public class GetAllFlowsByEndpointsResource extends ServerResource {
-    protected final static Logger log = LoggerFactory.getLogger(GetAllFlowsByEndpointsResource.class);
-
-    /**
-     * Implement the API.
-     *
-     * @return the collection of Flow states if any found, otherwise null.
-     */
-    @Get("json")
-    public ArrayList<FlowPath> retrieve() {
-	ArrayList<FlowPath> result = null;
-
-        IFlowService flowService =
-                (IFlowService)getContext().getAttributes().
-                get(IFlowService.class.getCanonicalName());
-
-        if (flowService == null) {
-	    log.debug("ONOS Flow Service not found");
-            return result;
-	}
-
-	// Extract the arguments
-        String srcDpidStr = (String) getRequestAttributes().get("src-dpid");
-        String srcPortStr = (String) getRequestAttributes().get("src-port");
-        String dstDpidStr = (String) getRequestAttributes().get("dst-dpid");
-        String dstPortStr = (String) getRequestAttributes().get("dst-port");
-
-	log.debug("Get All Flows Endpoints: " + srcDpidStr + "--" +
-		  srcPortStr + "--" + dstDpidStr + "--" + dstPortStr);
-
-	Dpid srcDpid = new Dpid(srcDpidStr);
-	Port srcPort = new Port(Short.parseShort(srcPortStr));
-	Dpid dstDpid = new Dpid(dstDpidStr);
-	Port dstPort = new Port(Short.parseShort(dstPortStr));
-	SwitchPort srcSwitchPort = new SwitchPort(srcDpid, srcPort);
-	SwitchPort dstSwitchPort = new SwitchPort(dstDpid, dstPort);
-	DataPathEndpoints dataPathEndpoints =
-	    new DataPathEndpoints(srcSwitchPort, dstSwitchPort);
-
-	result = flowService.getAllFlows(dataPathEndpoints);
-
-        return result;
-    }
-}
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/GetAllFlowsByInstallerIdResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/GetAllFlowsByInstallerIdResource.java
deleted file mode 100644
index 870548e..0000000
--- a/src/main/java/net/onrc/onos/ofcontroller/flowmanager/web/GetAllFlowsByInstallerIdResource.java
+++ /dev/null
@@ -1,82 +0,0 @@
-package net.onrc.onos.ofcontroller.flowmanager.web;
-
-import java.util.ArrayList;
-
-import net.onrc.onos.ofcontroller.flowmanager.IFlowService;
-import net.onrc.onos.ofcontroller.util.CallerId;
-import net.onrc.onos.ofcontroller.util.DataPathEndpoints;
-import net.onrc.onos.ofcontroller.util.Dpid;
-import net.onrc.onos.ofcontroller.util.FlowPath;
-import net.onrc.onos.ofcontroller.util.Port;
-import net.onrc.onos.ofcontroller.util.SwitchPort;
-
-import org.restlet.resource.Get;
-import org.restlet.resource.ServerResource;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-/**
- * Flow Manager REST API implementation: Get all Flow state for a given
- * Installer ID and given source and destination switches and ports.
- *
- * The "{installer-id}" request attribute value is the Installer ID of the
- * flows to get.
- * The "{src-dpid}" request attribute value is the source DPID of the flows to
- * get.
- * The "{src-port}" request attribute value is the source port of the flows to
- * get.
- * The "{dst-dpid}" request attribute value is the destination DPID of the
- * flows to get.
- * The "{dst-port}" request attribute value is the destination port of the
- * flows to get.
- *
- *   GET /wm/flow/getall-by-installer-id/{installer-id}/{src-dpid}/{src-port}/{dst-dpid}/{dst-port}/json"
- */
-public class GetAllFlowsByInstallerIdResource extends ServerResource {
-    protected final static Logger log = LoggerFactory.getLogger(GetAllFlowsByInstallerIdResource.class);
-
-    /**
-     * Implement the API.
-     *
-     * @return the collection of Flow states if any found, otherwise null.
-     */
-    @Get("json")
-    public ArrayList<FlowPath> retrieve() {
-	ArrayList<FlowPath> result = null;
-
-        IFlowService flowService =
-                (IFlowService)getContext().getAttributes().
-                get(IFlowService.class.getCanonicalName());
-
-        if (flowService == null) {
-	    log.debug("ONOS Flow Service not found");
-            return result;
-	}
-
-	// Extract the arguments
-        String installerIdStr = (String) getRequestAttributes().get("installer-id");
-        String srcDpidStr = (String) getRequestAttributes().get("src-dpid");
-        String srcPortStr = (String) getRequestAttributes().get("src-port");
-        String dstDpidStr = (String) getRequestAttributes().get("dst-dpid");
-        String dstPortStr = (String) getRequestAttributes().get("dst-port");
-
-	log.debug("Get All Flow By Installer: " + installerIdStr +
-		  " Endpoints: " +
-		  srcDpidStr + "--" + srcPortStr + "--" +
-		  dstDpidStr + "--" + dstPortStr);
-
-	CallerId installerId = new CallerId(installerIdStr);
-	Dpid srcDpid = new Dpid(srcDpidStr);
-	Port srcPort = new Port(Short.parseShort(srcPortStr));
-	Dpid dstDpid = new Dpid(dstDpidStr);
-	Port dstPort = new Port(Short.parseShort(dstPortStr));
-	SwitchPort srcSwitchPort = new SwitchPort(srcDpid, srcPort);
-	SwitchPort dstSwitchPort = new SwitchPort(dstDpid, dstPort);
-	DataPathEndpoints dataPathEndpoints =
-	    new DataPathEndpoints(srcSwitchPort, dstSwitchPort);
-
-	result = flowService.getAllFlows(installerId, dataPathEndpoints);
-
-        return result;
-    }
-}
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/FlowPusher.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/FlowPusher.java
index 8f2469b..c3c7107 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/FlowPusher.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/FlowPusher.java
@@ -3,9 +3,11 @@
 import java.io.IOException;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -27,8 +29,7 @@
 import net.floodlightcontroller.threadpool.IThreadPoolService;
 import net.floodlightcontroller.util.MACAddress;
 import net.floodlightcontroller.util.OFMessageDamper;
-import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowEntry;
-import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowPath;
+import net.onrc.onos.ofcontroller.flowmanager.IFlowService;
 import net.onrc.onos.ofcontroller.util.FlowEntryAction;
 import net.onrc.onos.ofcontroller.util.FlowEntryAction.*;
 import net.onrc.onos.ofcontroller.util.FlowEntry;
@@ -36,8 +37,8 @@
 import net.onrc.onos.ofcontroller.util.FlowEntryId;
 import net.onrc.onos.ofcontroller.util.FlowEntryMatch;
 import net.onrc.onos.ofcontroller.util.FlowEntryUserState;
-import net.onrc.onos.ofcontroller.util.FlowPath;
 import net.onrc.onos.ofcontroller.util.IPv4Net;
+import net.onrc.onos.ofcontroller.util.Pair;
 import net.onrc.onos.ofcontroller.util.Port;
 
 /**
@@ -54,6 +55,7 @@
  */
 public class FlowPusher implements IFlowPusherService, IOFMessageListener {
     private final static Logger log = LoggerFactory.getLogger(FlowPusher.class);
+    protected volatile IFlowService flowManager;
 
     // NOTE: Below are moved from FlowManager.
     // TODO: Values copied from elsewhere (class LearningSwitch).
@@ -157,7 +159,7 @@
 					// wait for message pushed to queue
 					mutex.acquire();
 				} catch (InterruptedException e) {
-					e.printStackTrace();
+					// not an error
 					log.debug("FlowPusherThread is interrupted");
 					return;
 				}
@@ -224,7 +226,7 @@
 					OFMessage msg = queue.poll();
 					try {
 						messageDamper.write(sw, msg, context);
-						log.debug("Pusher sends message : {}", msg);
+//						log.debug("Pusher sends message : {}", msg);
 						size += msg.getLength();
 					} catch (IOException e) {
 						e.printStackTrace();
@@ -270,6 +272,7 @@
 		this.threadPool = modContext.getServiceImpl(IThreadPoolService.class);
 		IFloodlightProviderService flservice = modContext.getServiceImpl(IFloodlightProviderService.class);
 		flservice.addOFMessageListener(OFType.BARRIER_REPLY, this);
+		flowManager = modContext.getServiceImpl(IFlowService.class);
 		
 		if (damper != null) {
 			messageDamper = damper;
@@ -327,6 +330,13 @@
 		synchronized (queue) {
 			if (queue.state == QueueState.SUSPENDED) {
 				queue.state = QueueState.READY;
+				
+				// Latch down if queue is not empty
+				FlowPusherThread thread = getProcess(sw);
+				if (! queue.isEmpty() &&
+						thread.mutex.availablePermits() == 0) {
+					thread.mutex.release();
+				}
 				return true;
 			}
 			return false;
@@ -430,7 +440,7 @@
 		
 		synchronized (queue) {
 			queue.add(msg);
-			log.debug("Message is pushed : {}", msg);
+//			log.debug("Message is pushed : {}", msg);
 		}
 		
 		if (proc.mutex.availablePermits() == 0) {
@@ -439,314 +449,46 @@
 
 		return true;
 	}
-	
+
 	@Override
-	public boolean add(IOFSwitch sw, IFlowPath flowObj, IFlowEntry flowEntryObj) {
-		log.debug("sending : {}, {}", sw, flowObj);
-		String flowEntryIdStr = flowEntryObj.getFlowEntryId();
-		if (flowEntryIdStr == null)
-		    return false;
-		FlowEntryId flowEntryId = new FlowEntryId(flowEntryIdStr);
-		String userState = flowEntryObj.getUserState();
-		if (userState == null)
-		    return false;
+	public void pushFlowEntries(
+		Collection<Pair<IOFSwitch, FlowEntry>> entries) {
 
-		//
-		// Create the Open Flow Flow Modification Entry to push
-		//
-		OFFlowMod fm = (OFFlowMod)factory.getMessage(OFType.FLOW_MOD);
-		long cookie = flowEntryId.value();
+		List<Pair<IOFSwitch, FlowEntry>> pushedEntries =
+			new LinkedList<Pair<IOFSwitch, FlowEntry>>();
 
-		short flowModCommand = OFFlowMod.OFPFC_ADD;
-		if (userState.equals("FE_USER_ADD")) {
-		    flowModCommand = OFFlowMod.OFPFC_ADD;
-		} else if (userState.equals("FE_USER_MODIFY")) {
-		    flowModCommand = OFFlowMod.OFPFC_MODIFY_STRICT;
-		} else if (userState.equals("FE_USER_DELETE")) {
-		    flowModCommand = OFFlowMod.OFPFC_DELETE_STRICT;
-		} else {
-		    // Unknown user state. Ignore the entry
-		    log.debug("Flow Entry ignored (FlowEntryId = {}): unknown user state {}",
-			      flowEntryId.toString(), userState);
-		    return false;
+		for (Pair<IOFSwitch, FlowEntry> entry : entries) {
+			if (add(entry.first, entry.second)) {
+				pushedEntries.add(entry);
+			}
 		}
 
 		//
-		// Fetch the match conditions.
+		// TODO: We should use the OpenFlow Barrier mechanism
+		// to check for errors, and update the SwitchState
+		// for a flow entry after the Barrier message is
+		// is received.
+		// Only after inform the Flow Manager that the entry is pushed.
 		//
-		// NOTE: The Flow matching conditions common for all Flow Entries are
-		// used ONLY if a Flow Entry does NOT have the corresponding matching
-		// condition set.
-		//
-		OFMatch match = new OFMatch();
-		match.setWildcards(OFMatch.OFPFW_ALL);
-
-		// Match the Incoming Port
-		Short matchInPort = flowEntryObj.getMatchInPort();
-		if (matchInPort != null) {
-		    match.setInputPort(matchInPort);
-		    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_IN_PORT);
-		}
-
-		// Match the Source MAC address
-		String matchSrcMac = flowEntryObj.getMatchSrcMac();
-		if (matchSrcMac == null)
-		    matchSrcMac = flowObj.getMatchSrcMac();
-		if (matchSrcMac != null) {
-		    match.setDataLayerSource(matchSrcMac);
-		    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_SRC);
-		}
-
-		// Match the Destination MAC address
-		String matchDstMac = flowEntryObj.getMatchDstMac();
-		if (matchDstMac == null)
-		    matchDstMac = flowObj.getMatchDstMac();
-		if (matchDstMac != null) {
-		    match.setDataLayerDestination(matchDstMac);
-		    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_DST);
-		}
-
-		// Match the Ethernet Frame Type
-		Short matchEthernetFrameType = flowEntryObj.getMatchEthernetFrameType();
-		if (matchEthernetFrameType == null)
-		    matchEthernetFrameType = flowObj.getMatchEthernetFrameType();
-		if (matchEthernetFrameType != null) {
-		    match.setDataLayerType(matchEthernetFrameType);
-		    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_TYPE);
-		}
-
-		// Match the VLAN ID
-		Short matchVlanId = flowEntryObj.getMatchVlanId();
-		if (matchVlanId == null)
-		    matchVlanId = flowObj.getMatchVlanId();
-		if (matchVlanId != null) {
-		    match.setDataLayerVirtualLan(matchVlanId);
-		    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_VLAN);
-		}
-
-		// Match the VLAN priority
-		Byte matchVlanPriority = flowEntryObj.getMatchVlanPriority();
-		if (matchVlanPriority == null)
-		    matchVlanPriority = flowObj.getMatchVlanPriority();
-		if (matchVlanPriority != null) {
-		    match.setDataLayerVirtualLanPriorityCodePoint(matchVlanPriority);
-		    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_DL_VLAN_PCP);
-		}
-
-		// Match the Source IPv4 Network prefix
-		String matchSrcIPv4Net = flowEntryObj.getMatchSrcIPv4Net();
-		if (matchSrcIPv4Net == null)
-		    matchSrcIPv4Net = flowObj.getMatchSrcIPv4Net();
-		if (matchSrcIPv4Net != null) {
-		    match.setFromCIDR(matchSrcIPv4Net, OFMatch.STR_NW_SRC);
-		}
-
-		// Match the Destination IPv4 Network prefix
-		String matchDstIPv4Net = flowEntryObj.getMatchDstIPv4Net();
-		if (matchDstIPv4Net == null)
-		    matchDstIPv4Net = flowObj.getMatchDstIPv4Net();
-		if (matchDstIPv4Net != null) {
-		    match.setFromCIDR(matchDstIPv4Net, OFMatch.STR_NW_DST);
-		}
-
-		// Match the IP protocol
-		Byte matchIpProto = flowEntryObj.getMatchIpProto();
-		if (matchIpProto == null)
-		    matchIpProto = flowObj.getMatchIpProto();
-		if (matchIpProto != null) {
-		    match.setNetworkProtocol(matchIpProto);
-		    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_NW_PROTO);
-		}
-
-		// Match the IP ToS (DSCP field, 6 bits)
-		Byte matchIpToS = flowEntryObj.getMatchIpToS();
-		if (matchIpToS == null)
-		    matchIpToS = flowObj.getMatchIpToS();
-		if (matchIpToS != null) {
-		    match.setNetworkTypeOfService(matchIpToS);
-		    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_NW_TOS);
-		}
-
-		// Match the Source TCP/UDP port
-		Short matchSrcTcpUdpPort = flowEntryObj.getMatchSrcTcpUdpPort();
-		if (matchSrcTcpUdpPort == null)
-		    matchSrcTcpUdpPort = flowObj.getMatchSrcTcpUdpPort();
-		if (matchSrcTcpUdpPort != null) {
-		    match.setTransportSource(matchSrcTcpUdpPort);
-		    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_TP_SRC);
-		}
-
-		// Match the Destination TCP/UDP port
-		Short matchDstTcpUdpPort = flowEntryObj.getMatchDstTcpUdpPort();
-		if (matchDstTcpUdpPort == null)
-		    matchDstTcpUdpPort = flowObj.getMatchDstTcpUdpPort();
-		if (matchDstTcpUdpPort != null) {
-		    match.setTransportDestination(matchDstTcpUdpPort);
-		    match.setWildcards(match.getWildcards() & ~OFMatch.OFPFW_TP_DST);
-		}
-
-		//
-		// Fetch the actions
-		//
-		Short actionOutputPort = null;
-		List<OFAction> openFlowActions = new ArrayList<OFAction>();
-		int actionsLen = 0;
-		FlowEntryActions flowEntryActions = null;
-		String actionsStr = flowEntryObj.getActions();
-		if (actionsStr != null)
-		    flowEntryActions = new FlowEntryActions(actionsStr);
-		else
-		    flowEntryActions = new FlowEntryActions();
-		for (FlowEntryAction action : flowEntryActions.actions()) {
-		    ActionOutput actionOutput = action.actionOutput();
-		    ActionSetVlanId actionSetVlanId = action.actionSetVlanId();
-		    ActionSetVlanPriority actionSetVlanPriority = action.actionSetVlanPriority();
-		    ActionStripVlan actionStripVlan = action.actionStripVlan();
-		    ActionSetEthernetAddr actionSetEthernetSrcAddr = action.actionSetEthernetSrcAddr();
-		    ActionSetEthernetAddr actionSetEthernetDstAddr = action.actionSetEthernetDstAddr();
-		    ActionSetIPv4Addr actionSetIPv4SrcAddr = action.actionSetIPv4SrcAddr();
-		    ActionSetIPv4Addr actionSetIPv4DstAddr = action.actionSetIPv4DstAddr();
-		    ActionSetIpToS actionSetIpToS = action.actionSetIpToS();
-		    ActionSetTcpUdpPort actionSetTcpUdpSrcPort = action.actionSetTcpUdpSrcPort();
-		    ActionSetTcpUdpPort actionSetTcpUdpDstPort = action.actionSetTcpUdpDstPort();
-		    ActionEnqueue actionEnqueue = action.actionEnqueue();
-
-		    if (actionOutput != null) {
-				actionOutputPort = actionOutput.port().value();
-				// XXX: The max length is hard-coded for now
-				OFActionOutput ofa =
-				    new OFActionOutput(actionOutput.port().value(),
-						       (short)0xffff);
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-
-		    if (actionSetVlanId != null) {
-				OFActionVirtualLanIdentifier ofa =
-				    new OFActionVirtualLanIdentifier(actionSetVlanId.vlanId());
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-
-		    if (actionSetVlanPriority != null) {
-				OFActionVirtualLanPriorityCodePoint ofa =
-				    new OFActionVirtualLanPriorityCodePoint(actionSetVlanPriority.vlanPriority());
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-
-		    if (actionStripVlan != null) {
-				if (actionStripVlan.stripVlan() == true) {
-				    OFActionStripVirtualLan ofa = new OFActionStripVirtualLan();
-				    openFlowActions.add(ofa);
-				    actionsLen += ofa.getLength();
-				}
-		    }
-
-		    if (actionSetEthernetSrcAddr != null) {
-				OFActionDataLayerSource ofa = 
-				    new OFActionDataLayerSource(actionSetEthernetSrcAddr.addr().toBytes());
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-
-		    if (actionSetEthernetDstAddr != null) {
-				OFActionDataLayerDestination ofa =
-				    new OFActionDataLayerDestination(actionSetEthernetDstAddr.addr().toBytes());
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-
-		    if (actionSetIPv4SrcAddr != null) {
-				OFActionNetworkLayerSource ofa =
-				    new OFActionNetworkLayerSource(actionSetIPv4SrcAddr.addr().value());
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-
-		    if (actionSetIPv4DstAddr != null) {
-				OFActionNetworkLayerDestination ofa =
-				    new OFActionNetworkLayerDestination(actionSetIPv4DstAddr.addr().value());
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-
-		    if (actionSetIpToS != null) {
-				OFActionNetworkTypeOfService ofa =
-				    new OFActionNetworkTypeOfService(actionSetIpToS.ipToS());
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-
-		    if (actionSetTcpUdpSrcPort != null) {
-				OFActionTransportLayerSource ofa =
-				    new OFActionTransportLayerSource(actionSetTcpUdpSrcPort.port());
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-
-		    if (actionSetTcpUdpDstPort != null) {
-				OFActionTransportLayerDestination ofa =
-				    new OFActionTransportLayerDestination(actionSetTcpUdpDstPort.port());
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-
-		    if (actionEnqueue != null) {
-				OFActionEnqueue ofa =
-				    new OFActionEnqueue(actionEnqueue.port().value(),
-							actionEnqueue.queueId());
-				openFlowActions.add(ofa);
-				actionsLen += ofa.getLength();
-		    }
-		}
-
-		fm.setIdleTimeout(FLOWMOD_DEFAULT_IDLE_TIMEOUT)
-		    .setHardTimeout(FLOWMOD_DEFAULT_HARD_TIMEOUT)
-		    .setPriority(PRIORITY_DEFAULT)
-		    .setBufferId(OFPacketOut.BUFFER_ID_NONE)
-		    .setCookie(cookie)
-		    .setCommand(flowModCommand)
-		    .setMatch(match)
-		    .setActions(openFlowActions)
-		    .setLengthU(OFFlowMod.MINIMUM_LENGTH + actionsLen);
-		fm.setOutPort(OFPort.OFPP_NONE.getValue());
-		if ((flowModCommand == OFFlowMod.OFPFC_DELETE) ||
-		    (flowModCommand == OFFlowMod.OFPFC_DELETE_STRICT)) {
-		    if (actionOutputPort != null)
-			fm.setOutPort(actionOutputPort);
-		}
-
-		//
-		// TODO: Set the following flag
-		// fm.setFlags(OFFlowMod.OFPFF_SEND_FLOW_REM);
-		// See method ForwardingBase::pushRoute()
-		//
-
-		//
-		// Write the message to the switch
-		//
-		log.debug("MEASUREMENT: Installing flow entry " + userState +
-			  " into switch DPID: " +
-			  sw.getStringId() +
-			  " flowEntryId: " + flowEntryId.toString() +
-			  " srcMac: " + matchSrcMac + " dstMac: " + matchDstMac +
-			  " inPort: " + matchInPort + " outPort: " + actionOutputPort
-			  );
-		add(sw,fm);
-	    //
-	    // TODO: We should use the OpenFlow Barrier mechanism
-	    // to check for errors, and update the SwitchState
-	    // for a flow entry after the Barrier message is
-	    // is received.
-	    //
-	    flowEntryObj.setSwitchState("FE_SWITCH_UPDATED");
-
-		return true;
+		flowManager.flowEntriesPushedToSwitch(pushedEntries);
 	}
-	
+
 	@Override
-	public boolean add(IOFSwitch sw, FlowPath flowPath, FlowEntry flowEntry) {
+	public void pushFlowEntry(IOFSwitch sw, FlowEntry flowEntry) {
+	    Collection<Pair<IOFSwitch, FlowEntry>> entries = 
+		new LinkedList<Pair<IOFSwitch, FlowEntry>>();
+
+	    entries.add(new Pair<IOFSwitch, FlowEntry>(sw, flowEntry));
+	    pushFlowEntries(entries);
+	}
+
+	/**
+	 * Create a message from FlowEntry and add it to the queue of the switch.
+	 * @param sw Switch to which message is pushed.
+	 * @param flowEntry FlowEntry object used for creating message.
+	 * @return true if message is successfully added to a queue.
+	 */
+	private boolean add(IOFSwitch sw, FlowEntry flowEntry) {
 		//
 		// Create the OpenFlow Flow Modification Entry to push
 		//
@@ -1003,24 +745,14 @@
 		//
 		// Write the message to the switch
 		//
-		log.debug("MEASUREMENT: Installing flow entry "
+		log.debug("Installing flow entry "
 				+ flowEntry.flowEntryUserState() + " into switch DPID: "
 				+ sw.getStringId() + " flowEntryId: "
 				+ flowEntry.flowEntryId().toString() + " srcMac: "
 				+ matchSrcMac + " dstMac: " + matchDstMac + " inPort: "
 				+ matchInPort + " outPort: " + actionOutputPort);
 		
-		//
-		// TODO: We should use the OpenFlow Barrier mechanism
-		// to check for errors, and update the SwitchState
-		// for a flow entry after the Barrier message is
-		// is received.
-		//
-		// TODO: The FlowEntry Object in Titan should be set
-		// to FE_SWITCH_UPDATED.
-		//
-		
-		return add(sw,fm);
+		return add(sw, fm);
 	}
 	
 	@Override
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/FlowSynchronizer.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/FlowSynchronizer.java
index c62bd5d..351df84 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/FlowSynchronizer.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/FlowSynchronizer.java
@@ -26,7 +26,9 @@
 import net.onrc.onos.graph.GraphDBManager;
 import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowEntry;
 import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.ISwitchObject;
+import net.onrc.onos.ofcontroller.flowmanager.FlowDatabaseOperation;
 import net.onrc.onos.ofcontroller.util.Dpid;
+import net.onrc.onos.ofcontroller.util.FlowEntry;
 import net.onrc.onos.ofcontroller.util.FlowEntryId;
 
 /**
@@ -237,7 +239,15 @@
 		return;
 	    }
 
-	    pusher.add(sw, iFlowEntry.getFlow(), iFlowEntry);
+	    FlowEntry flowEntry =
+		FlowDatabaseOperation.extractFlowEntry(iFlowEntry);
+	    if (flowEntry == null) {
+		log.error("Cannot add flow entry {} to sw {} : flow entry cannot be extracted",
+			  flowEntryId, sw.getId());
+		return;
+	    }
+
+	    pusher.pushFlowEntry(sw, flowEntry);
 	}
 	
 	/**
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/IFlowPusherService.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/IFlowPusherService.java
index 20a6249..6bf20d9 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/IFlowPusherService.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/IFlowPusherService.java
@@ -1,15 +1,15 @@
 package net.onrc.onos.ofcontroller.flowprogrammer;
 
+import java.util.Collection;
+
 import org.openflow.protocol.OFBarrierReply;
 import org.openflow.protocol.OFMessage;
 
 import net.floodlightcontroller.core.IOFSwitch;
 import net.floodlightcontroller.core.internal.OFMessageFuture;
 import net.floodlightcontroller.core.module.IFloodlightService;
-import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowEntry;
-import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowPath;
 import net.onrc.onos.ofcontroller.util.FlowEntry;
-import net.onrc.onos.ofcontroller.util.FlowPath;
+import net.onrc.onos.ofcontroller.util.Pair;
 
 /**
  * FlowPusherService is a service to send message to switches in proper rate.
@@ -50,6 +50,9 @@
 	
 	/**
 	 * Add a message to the queue of the switch.
+	 *
+	 * Note: Notification is NOT delivered for the pushed message.
+	 *
 	 * @param sw Switch to which message is pushed.
 	 * @param msg Message object to be added.
 	 * @return true if message is successfully added to a queue.
@@ -57,22 +60,28 @@
 	boolean add(IOFSwitch sw, OFMessage msg);
 
 	/**
-	 * Create a message from FlowEntry and add it to the queue of the switch.
+	 * Push a collection of Flow Entries to the corresponding switches.
+	 *
+	 * Note: Notification is delivered for the Flow Entries that
+	 * are pushed successfully.
+	 *
+	 * @param entries the collection of <IOFSwitch, FlowEntry> pairs
+	 * to push.
+	 */
+	void pushFlowEntries(Collection<Pair<IOFSwitch, FlowEntry>> entries);
+
+	/**
+	 * Create a message from FlowEntry and add it to the queue of the
+	 * switch.
+	 *
+	 * Note: Notification is delivered for the Flow Entries that
+	 * are pushed successfully.
+	 *
 	 * @param sw Switch to which message is pushed.
-	 * @param flowPath FlowPath object used for creating message.
 	 * @param flowEntry FlowEntry object used for creating message.
 	 * @return true if message is successfully added to a queue.
 	 */
-	boolean add(IOFSwitch sw, FlowPath flowPath, FlowEntry flowEntry);
-
-	/**
-	 * Create a message from IFlowEntry and add it to the queue of the switch.
-	 * @param sw Switch to which message is pushed.
-	 * @param flowObj IFlowPath object used for creating message.
-	 * @param flowEntryObj IFlowEntry object used for creating message.
-	 * @return true if message is successfully added to a queue.
-	 */
-	boolean add(IOFSwitch sw, IFlowPath flowObj, IFlowEntry flowEntryObj);
+	void pushFlowEntry(IOFSwitch sw, FlowEntry flowEntry);
 
 	/**
 	 * Set sending rate to a switch.
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/DoInterruptResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/DoInterruptResource.java
new file mode 100644
index 0000000..3c2920d
--- /dev/null
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/DoInterruptResource.java
@@ -0,0 +1,44 @@
+package net.onrc.onos.ofcontroller.flowprogrammer.web;
+
+import net.floodlightcontroller.core.IOFSwitch;
+
+import org.openflow.util.HexString;
+import org.restlet.resource.Get;
+
+/**
+ * FlowProgrammer REST API implementation: Interrupt synchronization to a switch.
+ *
+ *   GET /wm/fprog/synchronizer/interrupt/{dpid}/json"
+ */
+public class DoInterruptResource extends SynchronizerResource {
+
+    /**
+     * Implement the API.
+     *
+     * @return true if succeeded, false if failed.
+     */
+    @Get("json")
+    public boolean retrieve() {
+    	if (! init()) {
+    		return false;
+    	}
+    	
+    	long dpid;
+    	try {
+    		dpid = HexString.toLong((String)getRequestAttributes().get("dpid"));
+    	} catch (NumberFormatException e) {
+    		log.error("Invalid number format");
+    		return false;
+    	}
+
+    	IOFSwitch sw = provider.getSwitches().get(dpid);
+    	if (sw == null) {
+    		log.error("Invalid dpid");
+    		return false;
+    	}
+    	
+    	synchronizer.interrupt(sw);
+    	
+    	return true;
+    }
+}
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/DoSynchronizeResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/DoSynchronizeResource.java
new file mode 100644
index 0000000..dc8d431
--- /dev/null
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/DoSynchronizeResource.java
@@ -0,0 +1,44 @@
+package net.onrc.onos.ofcontroller.flowprogrammer.web;
+
+import net.floodlightcontroller.core.IOFSwitch;
+
+import org.openflow.util.HexString;
+import org.restlet.resource.Get;
+
+/**
+ * FlowProgrammer REST API implementation: Begin synchronization to a switch.
+ *
+ *   GET /wm/fprog/synchronizer/sync/{dpid}/json"
+ */
+public class DoSynchronizeResource extends SynchronizerResource {
+    /**
+     * Implement the API.
+     *
+     * @return true if succeeded, false if failed.
+     */
+    @Get("json")
+    public boolean retrieve() {
+    	if (! init()) {
+    		return false;
+    	}
+    	
+    	long dpid;
+    	try {
+    		dpid = HexString.toLong((String)getRequestAttributes().get("dpid"));
+    	} catch (NumberFormatException e) {
+    		log.error("Invalid number format");
+    		return false;
+    	}
+
+    	IOFSwitch sw = provider.getSwitches().get(dpid);
+    	if (sw == null) {
+    		log.error("Invalid dpid");
+    		return false;
+    	}
+    	
+    	synchronizer.synchronize(sw);
+    	
+    	return true;
+    }
+
+}
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/FlowProgrammerWebRoutable.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/FlowProgrammerWebRoutable.java
index 21e5bfb..22450f7 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/FlowProgrammerWebRoutable.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/FlowProgrammerWebRoutable.java
@@ -11,10 +11,12 @@
 	@Override
 	public Restlet getRestlet(Context context) {
 		Router router = new Router(context);
-		router.attach("/setrate/{dpid}/{rate}/json", SetPushRateResource.class);
-		router.attach("/suspend/{dpid}/json", SuspendPusherResource.class);
-		router.attach("/resume/{dpid}/json", ResumePusherResource.class);
-		router.attach("/barrier/{dpid}/json", SendBarrierResource.class);
+		router.attach("/pusher/setrate/{dpid}/{rate}/json", SetPushRateResource.class);
+		router.attach("/pusher/suspend/{dpid}/json", SuspendPusherResource.class);
+		router.attach("/pusher/resume/{dpid}/json", ResumePusherResource.class);
+		router.attach("/pusher/barrier/{dpid}/json", SendBarrierResource.class);
+		router.attach("/synchronizer/sync/{dpid}/json", DoSynchronizeResource.class);
+		router.attach("/synchronizer/interrupt/{dpid}/json", DoInterruptResource.class);
 		return router;
 	}
 
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/ResumePusherResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/ResumePusherResource.java
index ca1ec00..dcbe3e9 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/ResumePusherResource.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/ResumePusherResource.java
@@ -8,7 +8,7 @@
 /**
  * FlowProgrammer REST API implementation: Resume sending message to switch.
  *
- *   GET /wm/fprog/resume/{dpid}/json"
+ *   GET /wm/fprog/pusher/resume/{dpid}/json"
  */
 public class ResumePusherResource extends PusherResource {
     /**
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SendBarrierResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SendBarrierResource.java
index 9c348ff..33b666a 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SendBarrierResource.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SendBarrierResource.java
@@ -9,7 +9,7 @@
 /**
  * FlowProgrammer REST API implementation: Send barrier message to switch.
  *
- *   GET /wm/fprog/barrier/{dpid}/json"
+ *   GET /wm/fprog/pusher/barrier/{dpid}/json"
  */
 public class SendBarrierResource extends PusherResource {
     /**
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SetPushRateResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SetPushRateResource.java
index 08a728e..9431d65 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SetPushRateResource.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SetPushRateResource.java
@@ -8,7 +8,7 @@
 /**
  * FlowProgrammer REST API implementation: Set sending rate to the switch.
  *
- *   GET /wm/fprog/setrate/{dpid}/{rate}/json"
+ *   GET /wm/fprog/pusher/setrate/{dpid}/{rate}/json"
  */
 public class SetPushRateResource extends PusherResource {
 
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SuspendPusherResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SuspendPusherResource.java
index 39d245b..1a5266b 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SuspendPusherResource.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SuspendPusherResource.java
@@ -10,7 +10,7 @@
 /**
  * FlowProgrammer REST API implementation: Suspend sending message to switch.
  *
- *   GET /wm/fprog/suspend/{dpid}/json"
+ *   GET /wm/fprog/pusher/suspend/{dpid}/json"
  */
 public class SuspendPusherResource extends PusherResource {
 
diff --git a/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SynchronizerResource.java b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SynchronizerResource.java
new file mode 100644
index 0000000..12bf8f3
--- /dev/null
+++ b/src/main/java/net/onrc/onos/ofcontroller/flowprogrammer/web/SynchronizerResource.java
@@ -0,0 +1,35 @@
+package net.onrc.onos.ofcontroller.flowprogrammer.web;
+
+import net.floodlightcontroller.core.IFloodlightProviderService;
+import net.onrc.onos.ofcontroller.flowprogrammer.IFlowSyncService;
+
+import org.restlet.resource.ServerResource;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class SynchronizerResource extends ServerResource {
+    protected final static Logger log = LoggerFactory.getLogger(SynchronizerResource.class);
+    
+    protected IFloodlightProviderService provider;
+    protected IFlowSyncService synchronizer;
+
+    protected boolean init() {
+    	provider = (IFloodlightProviderService)
+    			getContext().getAttributes().
+    			get(IFloodlightProviderService.class.getCanonicalName());
+    	if (provider == null) {
+		    log.debug("ONOS FloodlightProvider not found");
+		    return false;
+		}
+    	
+    	synchronizer = (IFlowSyncService)
+    			getContext().getAttributes().
+    			get(IFlowSyncService.class.getCanonicalName());
+    	if (synchronizer == null) {
+		    log.debug("ONOS FlowSyncService not found");
+		    return false;
+		}
+    	
+    	return true;
+    }
+}
diff --git a/src/main/java/net/onrc/onos/ofcontroller/forwarding/Forwarding.java b/src/main/java/net/onrc/onos/ofcontroller/forwarding/Forwarding.java
index e5144ab..05de13e 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/forwarding/Forwarding.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/forwarding/Forwarding.java
@@ -1,6 +1,9 @@
 package net.onrc.onos.ofcontroller.forwarding;
 
+import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Iterator;
+import java.util.List;
 
 import net.floodlightcontroller.core.FloodlightContext;
 import net.floodlightcontroller.core.IFloodlightProviderService;
@@ -29,7 +32,11 @@
 
 import org.openflow.protocol.OFMessage;
 import org.openflow.protocol.OFPacketIn;
+import org.openflow.protocol.OFPacketOut;
+import org.openflow.protocol.OFPort;
 import org.openflow.protocol.OFType;
+import org.openflow.protocol.action.OFAction;
+import org.openflow.protocol.action.OFActionOutput;
 import org.openflow.util.HexString;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -127,6 +134,8 @@
 		ISwitchObject switchObject = portObject.getSwitch();
 		long destinationDpid = HexString.toLong(switchObject.getDPID());
 		
+		// TODO SwitchPort, Dpid and Port should probably be immutable
+		// (also, are Dpid and Port are even necessary?)
 		SwitchPort srcSwitchPort = new SwitchPort(
 				new Dpid(sw.getId()), new Port(pi.getInPort())); 
 		SwitchPort dstSwitchPort = new SwitchPort(
@@ -139,7 +148,31 @@
 				dstSwitchPort, dstMacAddress)) {
 			log.debug("Not adding flow because it already exists");
 			
-			// Don't do anything if the flow already exists
+			// TODO check reverse flow as well
+			
+			DataPath shortestPath = 
+					topologyService.getDatabaseShortestPath(srcSwitchPort, dstSwitchPort);
+			
+			if (shortestPath == null || shortestPath.flowEntries().isEmpty()) {
+				log.warn("No path found between {} and {} - not handling packet",
+						srcSwitchPort, dstSwitchPort);
+				return;
+			}
+			
+			Port outPort = shortestPath.flowEntries().get(0).outPort();
+			forwardPacket(pi, sw, outPort.value());
+			return;
+		}
+		
+		// Calculate a shortest path before pushing flow mods.
+		// This will be used later by the packet-out processing, but it uses
+		// the database so will be slow, and we should do it before flow mods.
+		DataPath shortestPath = 
+				topologyService.getDatabaseShortestPath(srcSwitchPort, dstSwitchPort);
+		
+		if (shortestPath == null || shortestPath.flowEntries().isEmpty()) {
+			log.warn("No path found between {} and {} - not handling packet",
+					srcSwitchPort, dstSwitchPort);
 			return;
 		}
 		
@@ -151,21 +184,53 @@
 		dataPath.setSrcPort(srcSwitchPort);
 		dataPath.setDstPort(dstSwitchPort);
 		
-		FlowId flowId = new FlowId(flowService.getNextFlowEntryId());
+		CallerId callerId = new CallerId("Forwarding");
+		
+		//FlowId flowId = new FlowId(flowService.getNextFlowEntryId());
 		FlowPath flowPath = new FlowPath();
-		flowPath.setFlowId(flowId);
-		flowPath.setInstallerId(new CallerId("Forwarding"));
+		//flowPath.setFlowId(flowId);
+		flowPath.setInstallerId(callerId);
+
 		flowPath.setFlowPathType(FlowPathType.FP_TYPE_SHORTEST_PATH);
 		flowPath.setFlowPathUserState(FlowPathUserState.FP_USER_ADD);
 		flowPath.setFlowEntryMatch(new FlowEntryMatch());
 		flowPath.flowEntryMatch().enableSrcMac(srcMacAddress);
 		flowPath.flowEntryMatch().enableDstMac(dstMacAddress);
 		// For now just forward IPv4 packets. This prevents accidentally
-		// other stuff like ARP.
+		// forwarding other stuff like ARP.
 		flowPath.flowEntryMatch().enableEthernetFrameType(Ethernet.TYPE_IPv4);
 		flowPath.setDataPath(dataPath);
+			
+		FlowId flowId = flowService.addFlow(flowPath);
+		//flowService.addFlow(flowPath, flowId);
 		
-		flowService.addFlow(flowPath, flowId);
+		
+		DataPath reverseDataPath = new DataPath();
+		// Reverse the ports for the reverse path
+		reverseDataPath.setSrcPort(dstSwitchPort);
+		reverseDataPath.setDstPort(srcSwitchPort);
+		
+		//FlowId reverseFlowId = new FlowId(flowService.getNextFlowEntryId());
+		// TODO implement copy constructor for FlowPath
+		FlowPath reverseFlowPath = new FlowPath();
+		//reverseFlowPath.setFlowId(reverseFlowId);
+		reverseFlowPath.setInstallerId(callerId);
+		reverseFlowPath.setFlowPathType(FlowPathType.FP_TYPE_SHORTEST_PATH);
+		reverseFlowPath.setFlowPathUserState(FlowPathUserState.FP_USER_ADD);
+		reverseFlowPath.setFlowEntryMatch(new FlowEntryMatch());
+		// Reverse the MAC addresses for the reverse path
+		reverseFlowPath.flowEntryMatch().enableSrcMac(dstMacAddress);
+		reverseFlowPath.flowEntryMatch().enableDstMac(srcMacAddress);
+		reverseFlowPath.flowEntryMatch().enableEthernetFrameType(Ethernet.TYPE_IPv4);
+		reverseFlowPath.setDataPath(reverseDataPath);
+		reverseFlowPath.dataPath().srcPort().dpid().toString();
+		
+		// TODO what happens if no path exists?
+		//flowService.addFlow(reverseFlowPath, reverseFlowId);
+		FlowId reverseFlowId = flowService.addFlow(reverseFlowPath);
+		
+		Port outPort = shortestPath.flowEntries().get(0).outPort();
+		forwardPacket(pi, sw, outPort.value());
 	}
 	
 	private boolean flowExists(SwitchPort srcPort, MACAddress srcMac, 
@@ -194,4 +259,31 @@
 		return false;
 	}
 
+	private void forwardPacket(OFPacketIn pi, IOFSwitch sw, short port) {
+		List<OFAction> actions = new ArrayList<OFAction>(1);
+		actions.add(new OFActionOutput(port));
+		
+		OFPacketOut po = new OFPacketOut();
+		po.setInPort(OFPort.OFPP_NONE)
+		.setInPort(pi.getInPort())
+		.setActions(actions)
+		.setActionsLength((short)OFActionOutput.MINIMUM_LENGTH)
+		.setLengthU(OFPacketOut.MINIMUM_LENGTH + OFActionOutput.MINIMUM_LENGTH);
+		
+		if (sw.getBuffers() == 0) {
+			po.setBufferId(OFPacketOut.BUFFER_ID_NONE)
+			.setPacketData(pi.getPacketData())
+			.setLengthU(po.getLengthU() + po.getPacketData().length);
+		}
+		else {
+			po.setBufferId(pi.getBufferId());
+		}
+		
+		try {
+			sw.write(po, null);
+			sw.flush();
+		} catch (IOException e) {
+			log.error("Error writing packet out to switch: {}", e);
+		}
+	}
 }
diff --git a/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ProxyArpManager.java b/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ProxyArpManager.java
index ec8065c..f6d8c9c 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ProxyArpManager.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ProxyArpManager.java
@@ -17,7 +17,6 @@
 import net.floodlightcontroller.core.IFloodlightProviderService;
 import net.floodlightcontroller.core.IOFMessageListener;
 import net.floodlightcontroller.core.IOFSwitch;
-import net.floodlightcontroller.devicemanager.IDevice;
 import net.floodlightcontroller.packet.ARP;
 import net.floodlightcontroller.packet.Ethernet;
 import net.floodlightcontroller.packet.IPv4;
@@ -35,6 +34,9 @@
 import net.onrc.onos.ofcontroller.core.internal.DeviceStorageImpl;
 import net.onrc.onos.ofcontroller.core.internal.TopoLinkServiceImpl;
 import net.onrc.onos.ofcontroller.core.internal.TopoSwitchServiceImpl;
+import net.onrc.onos.ofcontroller.util.Dpid;
+import net.onrc.onos.ofcontroller.util.Port;
+import net.onrc.onos.ofcontroller.util.SwitchPort;
 
 import org.openflow.protocol.OFMessage;
 import org.openflow.protocol.OFPacketIn;
@@ -246,21 +248,14 @@
 	public Command receive(
 			IOFSwitch sw, OFMessage msg, FloodlightContext cntx) {
 		
-		//if (msg.getType() != OFType.PACKET_IN){
-			//return Command.CONTINUE;
-		//}
-		log.debug("received packet");
-		
 		OFPacketIn pi = (OFPacketIn) msg;
 		
 		Ethernet eth = IFloodlightProviderService.bcStore.get(cntx, 
                 IFloodlightProviderService.CONTEXT_PI_PAYLOAD);
 		
 		if (eth.getEtherType() == Ethernet.TYPE_ARP){
-			log.debug("is arp");
 			ARP arp = (ARP) eth.getPayload();	
 			if (arp.getOpCode() == ARP.OP_REQUEST) {
-				log.debug("is request");
 				//TODO check what the DeviceManager does about propagating
 				//or swallowing ARPs. We want to go after DeviceManager in the
 				//chain but we really need it to CONTINUE ARP packets so we can
@@ -268,7 +263,6 @@
 				handleArpRequest(sw, pi, arp, eth);
 			}
 			else if (arp.getOpCode() == ARP.OP_REPLY) {
-				log.debug("is reply");
 				//handleArpReply(sw, pi, arp);
 			}
 		}
@@ -548,6 +542,8 @@
 	}
 	
 	private void broadcastArpRequestOutMyEdge(byte[] arpRequest) {
+		List<SwitchPort> switchPorts = new ArrayList<SwitchPort>();
+		
 		for (IOFSwitch sw : floodlightProvider.getSwitches().values()) {
 			
 			OFPacketOut po = new OFPacketOut();
@@ -565,6 +561,8 @@
 			
 			for (IPortObject portObject : ports) {
 				if (!portObject.getLinkedPorts().iterator().hasNext()) {
+					switchPorts.add(new SwitchPort(new Dpid(sw.getId()), 
+							new Port(portObject.getNumber())));
 					actions.add(new OFActionOutput(portObject.getNumber()));
 				}
 			}
@@ -583,6 +581,8 @@
 				log.error("Failure writing packet out to switch", e);
 			}
 		}
+		
+		log.debug("Broadcast ARP request for to: {}", switchPorts);
 	}
 	
 	private void sendArpRequestOutPort(byte[] arpRequest, long dpid, short port) {
@@ -722,13 +722,17 @@
 	
 	@Override
 	public void arpRequestNotification(ArpMessage arpMessage) {
-		log.debug("Received ARP notification from other instances");
+		//log.debug("Received ARP notification from other instances");
 		
 		switch (arpMessage.getType()){
 		case REQUEST:
+			log.debug("Received ARP request notification for {}", 
+					arpMessage.getAddress());
 			broadcastArpRequestOutMyEdge(arpMessage.getPacket());
 			break;
 		case REPLY:
+			log.debug("Received ARP reply notification for {}",
+					arpMessage.getAddress());
 			sendArpReplyToWaitingRequesters(arpMessage.getAddress());
 			break;
 		}
diff --git a/src/main/java/net/onrc/onos/ofcontroller/util/FlowPath.java b/src/main/java/net/onrc/onos/ofcontroller/util/FlowPath.java
index a720fc6..ab3edb1 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/util/FlowPath.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/util/FlowPath.java
@@ -6,6 +6,7 @@
 import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowEntry;
 import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowPath;
 
+import org.codehaus.jackson.annotate.JsonIgnore;
 import org.codehaus.jackson.annotate.JsonProperty;
 
 /**
@@ -210,6 +211,18 @@
     }
 
     /**
+     * Test whether the Flow ID is valid.
+     *
+     * @return true if the Flow ID is valid, otherwise false.
+     */
+    @JsonIgnore
+    public boolean isValidFlowId() {
+	if (this.flowId == null)
+	    return false;
+	return (this.flowId.isValid());
+    }
+
+    /**
      * Get the Caller ID of the flow path installer.
      *
      * @return the Caller ID of the flow path installer.
diff --git a/src/main/java/net/onrc/onos/ofcontroller/util/Pair.java b/src/main/java/net/onrc/onos/ofcontroller/util/Pair.java
new file mode 100644
index 0000000..2245758
--- /dev/null
+++ b/src/main/java/net/onrc/onos/ofcontroller/util/Pair.java
@@ -0,0 +1,20 @@
+package net.onrc.onos.ofcontroller.util;
+
+/**
+ * A generic class representing a pair of two values.
+ */
+public class Pair<F, S> {
+    public F first;		// The first value in the pair
+    public S second;		// The second value in the pair
+
+    /**
+     * Constructor for a pair of two values.
+     *
+     * @param first the first value in the pair.
+     * @param second the second value in the pair.
+     */
+    public Pair(F first, S second) {
+	this.first = first;
+	this.second = second;
+    }
+}