diff --git a/src/main/java/net/onrc/onos/core/topology/NetworkGraphDatastore.java b/src/main/java/net/onrc/onos/core/topology/NetworkGraphDatastore.java
index 8488297..488915f 100644
--- a/src/main/java/net/onrc/onos/core/topology/NetworkGraphDatastore.java
+++ b/src/main/java/net/onrc/onos/core/topology/NetworkGraphDatastore.java
@@ -26,203 +26,202 @@
  * mutate the graph. This class will maintain the invariants of the network
  * graph. The southbound discovery modules will use this interface to update
  * the network graph as they learn about the state of the network.
- *
+ * <p/>
  * Modification to the Network Map by this module will:
  * 1. Writes to Cluster-wide DataStore.
  * 2. Update ONOS instance In-memory Network Map.
  * 3. Send-out Notification. (TBD)
- *    (XXX: To update other instances In-memory Network Map,
- *          notification should be triggered here.
- *          But if we want to aggregate notification to minimize notification,
- *          It might be better for the caller to trigger notification.)
- *
+ * (XXX: To update other instances In-memory Network Map,
+ * notification should be triggered here.
+ * But if we want to aggregate notification to minimize notification,
+ * It might be better for the caller to trigger notification.)
  */
 public class NetworkGraphDatastore {
-	private static final Logger log = LoggerFactory.getLogger(NetworkGraphDatastore.class);
+    private static final Logger log = LoggerFactory.getLogger(NetworkGraphDatastore.class);
 
-	/**
-	 * Add a switch to the database.
-	 *
-	 * @param sw the switch to add.
-	 * @param portEvents the corresponding switch ports to add.
-	 * @return true on success, otherwise false.
-	 */
-	public boolean addSwitch(SwitchEvent sw,
-				 Collection<PortEvent> portEvents) {
-		log.debug("Adding switch {}", sw);
-		ArrayList<WriteOp> groupOp = new ArrayList<>();
+    /**
+     * Add a switch to the database.
+     *
+     * @param sw         the switch to add.
+     * @param portEvents the corresponding switch ports to add.
+     * @return true on success, otherwise false.
+     */
+    public boolean addSwitch(SwitchEvent sw,
+                             Collection<PortEvent> portEvents) {
+        log.debug("Adding switch {}", sw);
+        ArrayList<WriteOp> groupOp = new ArrayList<>();
 
-		KVSwitch rcSwitch = new KVSwitch(sw.getDpid());
-		rcSwitch.setStatus(KVSwitch.STATUS.ACTIVE);
+        KVSwitch rcSwitch = new KVSwitch(sw.getDpid());
+        rcSwitch.setStatus(KVSwitch.STATUS.ACTIVE);
 
-		IKVClient client = DataStoreClient.getClient();
+        IKVClient client = DataStoreClient.getClient();
 
-		// XXX Is ForceCreating Switch on DB OK here?
-		// If ForceCreating, who ever is calling this method needs
-		// to assure that DPID is unique cluster-wide, etc.
-		groupOp.add(rcSwitch.forceCreateOp(client));
+        // XXX Is ForceCreating Switch on DB OK here?
+        // If ForceCreating, who ever is calling this method needs
+        // to assure that DPID is unique cluster-wide, etc.
+        groupOp.add(rcSwitch.forceCreateOp(client));
 
-		for (PortEvent portEvent : portEvents) {
-			KVPort rcPort = new KVPort(sw.getDpid(), portEvent.getNumber());
-			rcPort.setStatus(KVPort.STATUS.ACTIVE);
+        for (PortEvent portEvent : portEvents) {
+            KVPort rcPort = new KVPort(sw.getDpid(), portEvent.getNumber());
+            rcPort.setStatus(KVPort.STATUS.ACTIVE);
 
-			groupOp.add(rcPort.forceCreateOp(client));
-		}
+            groupOp.add(rcPort.forceCreateOp(client));
+        }
 
-		boolean failed = KVObject.multiWrite(groupOp);
+        boolean failed = KVObject.multiWrite(groupOp);
 
-		if (failed) {
-		    log.error("Adding Switch {} and its ports failed.", sw.getDpid());
-		    for (WriteOp op : groupOp) {
-			log.debug("Operation:{} for {} - Result:{}", op.getOp(), op.getObject(), op.getStatus() );
+        if (failed) {
+            log.error("Adding Switch {} and its ports failed.", sw.getDpid());
+            for (WriteOp op : groupOp) {
+                log.debug("Operation:{} for {} - Result:{}", op.getOp(), op.getObject(), op.getStatus());
 
-			// If we changed the operation from ForceCreate to
-			// Conditional operation (Create/Update) then we should retry here.
-		    }
-		}
-		return !failed;
-	}
+                // If we changed the operation from ForceCreate to
+                // Conditional operation (Create/Update) then we should retry here.
+            }
+        }
+        return !failed;
+    }
 
-	/**
-	 * Update a switch as inactive in the database.
-	 *
-	 * @param sw the switch to update.
-	 * @param portEvents the corresponding switch ports to update.
-	 * @return true on success, otherwise false.
-	 */
-	public boolean deactivateSwitch(SwitchEvent sw,
-					Collection<PortEvent> portEvents) {
-		log.debug("Deactivating switch {}", sw);
-		KVSwitch rcSwitch = new KVSwitch(sw.getDpid());
+    /**
+     * Update a switch as inactive in the database.
+     *
+     * @param sw         the switch to update.
+     * @param portEvents the corresponding switch ports to update.
+     * @return true on success, otherwise false.
+     */
+    public boolean deactivateSwitch(SwitchEvent sw,
+                                    Collection<PortEvent> portEvents) {
+        log.debug("Deactivating switch {}", sw);
+        KVSwitch rcSwitch = new KVSwitch(sw.getDpid());
 
-		IKVClient client = DataStoreClient.getClient();
+        IKVClient client = DataStoreClient.getClient();
 
-		List<WriteOp> groupOp = new ArrayList<>();
-		rcSwitch.setStatus(KVSwitch.STATUS.INACTIVE);
+        List<WriteOp> groupOp = new ArrayList<>();
+        rcSwitch.setStatus(KVSwitch.STATUS.INACTIVE);
 
-		groupOp.add(rcSwitch.forceCreateOp(client));
+        groupOp.add(rcSwitch.forceCreateOp(client));
 
-		for (PortEvent portEvent : portEvents) {
-			KVPort rcPort = new KVPort(sw.getDpid(), portEvent.getNumber());
-			rcPort.setStatus(KVPort.STATUS.INACTIVE);
+        for (PortEvent portEvent : portEvents) {
+            KVPort rcPort = new KVPort(sw.getDpid(), portEvent.getNumber());
+            rcPort.setStatus(KVPort.STATUS.INACTIVE);
 
-			groupOp.add(rcPort.forceCreateOp(client));
-		}
+            groupOp.add(rcPort.forceCreateOp(client));
+        }
 
-		boolean failed = KVObject.multiWrite(groupOp);
+        boolean failed = KVObject.multiWrite(groupOp);
 
-		return !failed;
-	}
+        return !failed;
+    }
 
-	/**
-	 * Add a port to the database.
-	 *
-	 * @param port the port to add.
-	 * @return true on success, otherwise false.
-	 */
-	public boolean addPort(PortEvent port) {
-		log.debug("Adding port {}", port);
+    /**
+     * Add a port to the database.
+     *
+     * @param port the port to add.
+     * @return true on success, otherwise false.
+     */
+    public boolean addPort(PortEvent port) {
+        log.debug("Adding port {}", port);
 
-		KVPort rcPort = new KVPort(port.getDpid(), port.getNumber());
-		rcPort.setStatus(KVPort.STATUS.ACTIVE);
-		rcPort.forceCreate();
-		// TODO add description into KVPort
-		//rcPort.setDescription(port.getDescription());
+        KVPort rcPort = new KVPort(port.getDpid(), port.getNumber());
+        rcPort.setStatus(KVPort.STATUS.ACTIVE);
+        rcPort.forceCreate();
+        // TODO add description into KVPort
+        //rcPort.setDescription(port.getDescription());
 
-		return true;
-	}
+        return true;
+    }
 
-	/**
-	 * Update a port as inactive in the database.
-	 *
-	 * @param port the port to update.
-	 * @return true on success, otherwise false.
-	 */
-	public boolean deactivatePort(PortEvent port) {
-		log.debug("Deactivating port {}", port);
+    /**
+     * Update a port as inactive in the database.
+     *
+     * @param port the port to update.
+     * @return true on success, otherwise false.
+     */
+    public boolean deactivatePort(PortEvent port) {
+        log.debug("Deactivating port {}", port);
 
-		KVPort rcPort = new KVPort(port.getDpid(), port.getNumber());
-		rcPort.setStatus(STATUS.INACTIVE);
+        KVPort rcPort = new KVPort(port.getDpid(), port.getNumber());
+        rcPort.setStatus(STATUS.INACTIVE);
 
-		rcPort.forceCreate();
+        rcPort.forceCreate();
 
-		return true;
-	}
+        return true;
+    }
 
-	/**
-	 * Add a link to the database.
-	 *
-	 * @param link the link to add.
-	 * @return true on success, otherwise false.
-	 */
-	public boolean addLink(LinkEvent link) {
-		log.debug("Adding link {}", link);
+    /**
+     * Add a link to the database.
+     *
+     * @param link the link to add.
+     * @return true on success, otherwise false.
+     */
+    public boolean addLink(LinkEvent link) {
+        log.debug("Adding link {}", link);
 
-		KVLink rcLink = new KVLink(link.getSrc().getDpid(),
-					   link.getSrc().getNumber(),
-					   link.getDst().getDpid(),
-					   link.getDst().getNumber());
+        KVLink rcLink = new KVLink(link.getSrc().getDpid(),
+                link.getSrc().getNumber(),
+                link.getDst().getDpid(),
+                link.getDst().getNumber());
 
-		// XXX This method is called only by discovery,
-		// which means what we are trying to write currently is the truth
-		// so we can force write here
-		//
-		// TODO: We need to check for errors
-		rcLink.setStatus(KVLink.STATUS.ACTIVE);
-		rcLink.forceCreate();
+        // XXX This method is called only by discovery,
+        // which means what we are trying to write currently is the truth
+        // so we can force write here
+        //
+        // TODO: We need to check for errors
+        rcLink.setStatus(KVLink.STATUS.ACTIVE);
+        rcLink.forceCreate();
 
-		return true;					// Success
-	}
+        return true;                    // Success
+    }
 
-	public boolean removeLink(LinkEvent linkEvent) {
-		log.debug("Removing link {}", linkEvent);
+    public boolean removeLink(LinkEvent linkEvent) {
+        log.debug("Removing link {}", linkEvent);
 
-		KVLink rcLink = new KVLink(linkEvent.getSrc().getDpid(), linkEvent.getSrc().getNumber(),
-				linkEvent.getDst().getDpid(), linkEvent.getDst().getNumber());
-		rcLink.forceDelete();
+        KVLink rcLink = new KVLink(linkEvent.getSrc().getDpid(), linkEvent.getSrc().getNumber(),
+                linkEvent.getDst().getDpid(), linkEvent.getDst().getNumber());
+        rcLink.forceDelete();
 
-		return true;
-	}
+        return true;
+    }
 
-	/**
-	 * Add a device to the database.
-	 *
-	 * @param device the device to add.
-	 * @return true on success, otherwise false.
-	 */
-	public boolean addDevice(DeviceEvent device) {
-		log.debug("Adding device into DB. mac {}", device.getMac());
+    /**
+     * Add a device to the database.
+     *
+     * @param device the device to add.
+     * @return true on success, otherwise false.
+     */
+    public boolean addDevice(DeviceEvent device) {
+        log.debug("Adding device into DB. mac {}", device.getMac());
 
-		KVDevice rcDevice = new KVDevice(device.getMac().toBytes());
-		rcDevice.setLastSeenTime(device.getLastSeenTime());
-		
-		for(SwitchPort sp : device.getAttachmentPoints()) {
-			byte[] portId = KVPort.getPortID(sp.getDpid(), sp.getNumber());		
-			rcDevice.addPortId(portId);
-		}
-		
-		for(InetAddress addr : device.getIpAddresses()) {
-			//It assume only one ip on a device now.
-			rcDevice.setIp(InetAddresses.coerceToInteger(addr));	
-		}
+        KVDevice rcDevice = new KVDevice(device.getMac().toBytes());
+        rcDevice.setLastSeenTime(device.getLastSeenTime());
 
-		rcDevice.forceCreate();
-		
-		return true;
-	}
+        for (SwitchPort sp : device.getAttachmentPoints()) {
+            byte[] portId = KVPort.getPortID(sp.getDpid(), sp.getNumber());
+            rcDevice.addPortId(portId);
+        }
 
-	/**
-	 * Remove a device from the database.
-	 *
-	 * @param device the device to remove.
-	 * @return true on success, otherwise false.
-	 */
-	public boolean removeDevice(DeviceEvent device) {
-		log.debug("Removing device into DB. mac {}", device.getMac());
-		
-		KVDevice rcDevice = new KVDevice(device.getMac().toBytes());
-		rcDevice.forceDelete();
-		
-		return true;
-	}
+        for (InetAddress addr : device.getIpAddresses()) {
+            //It assume only one ip on a device now.
+            rcDevice.setIp(InetAddresses.coerceToInteger(addr));
+        }
+
+        rcDevice.forceCreate();
+
+        return true;
+    }
+
+    /**
+     * Remove a device from the database.
+     *
+     * @param device the device to remove.
+     * @return true on success, otherwise false.
+     */
+    public boolean removeDevice(DeviceEvent device) {
+        log.debug("Removing device into DB. mac {}", device.getMac());
+
+        KVDevice rcDevice = new KVDevice(device.getMac().toBytes());
+        rcDevice.forceDelete();
+
+        return true;
+    }
 }