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 bddc74b..d71848b 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/floodlightlistener/NetworkGraphPublisher.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/floodlightlistener/NetworkGraphPublisher.java
@@ -41,30 +41,38 @@
 
 import com.google.common.net.InetAddresses;
 
+/**
+ * The NetworkGraphPublisher subscribes to topology network events from the
+ * discovery modules. These events are reformatted and relayed to the topology
+ * part of the network graph
+ *
+ */
 public class NetworkGraphPublisher implements /*IOFSwitchListener,*/
-												IOFSwitchPortListener,
-												ILinkDiscoveryListener,
-												IFloodlightModule,
-												IOnosDeviceListener {
-	private static final Logger log = LoggerFactory.getLogger(NetworkGraphPublisher.class);
+                                    IOFSwitchPortListener,
+                                    ILinkDiscoveryListener,
+                                    IFloodlightModule,
+                                    IOnosDeviceListener {
+    private static final Logger log =
+            LoggerFactory.getLogger(NetworkGraphPublisher.class);
 
-	private IFloodlightProviderService floodlightProvider;
-	private ILinkDiscoveryService linkDiscovery;
-	private IControllerRegistryService registryService;
-	private INetworkGraphService networkGraphService;
+    private IFloodlightProviderService floodlightProvider;
+    private ILinkDiscoveryService linkDiscovery;
+    private IControllerRegistryService registryService;
+    private INetworkGraphService networkGraphService;
 
-	private IOnosDeviceService onosDeviceService;
+    private IOnosDeviceService onosDeviceService;
 
-	private NetworkGraph networkGraph;
-	private NetworkGraphDiscoveryInterface networkGraphDiscoveryInterface;
+    private NetworkGraph networkGraph;
+    private NetworkGraphDiscoveryInterface networkGraphDiscoveryInterface;
 
-	private static final String ENABLE_CLEANUP_PROPERTY = "EnableCleanup";
-	private boolean cleanupEnabled = true;
-	private static final int CLEANUP_TASK_INTERVAL = 60; // in seconds
-	private SingletonTask cleanupTask;
+    private static final String ENABLE_CLEANUP_PROPERTY = "EnableCleanup";
+    private boolean cleanupEnabled = true;
+    private static final int CLEANUP_TASK_INTERVAL = 60; // in seconds
+    private SingletonTask cleanupTask;
 
     /**
-     *  Cleanup and synch switch state from registry
+     * Cleanup old switches from the network graph. Old switches are those
+     * which have no controller in the registry.
      */
     private class SwitchCleanup implements ControlChangeCallback, Runnable {
         @Override
@@ -73,142 +81,158 @@
             Thread.currentThread().setName("SwitchCleanup@" + old);
 
             try {
-            	log.debug("Running cleanup thread");
+                if (log.isTraceEnabled()) {
+                    log.trace("Running cleanup thread");
+                }
                 switchCleanup();
-            }
-            catch (Exception e) {
-                log.error("Error in cleanup thread", e);
             } finally {
                 cleanupTask.reschedule(CLEANUP_TASK_INTERVAL,
-                                          TimeUnit.SECONDS);
+                        TimeUnit.SECONDS);
                 Thread.currentThread().setName(old);
             }
         }
 
+        /**
+         * First half of the switch cleanup operation. This method will attempt
+         * to get control of any switch it sees without a controller via the
+         * registry.
+         */
         private void switchCleanup() {
-        	Iterable<Switch> switches = networkGraph.getSwitches();
+            Iterable<Switch> switches = networkGraph.getSwitches();
 
-        	log.debug("Checking for inactive switches");
-        	// For each switch check if a controller exists in controller registry
-        	for (Switch sw: switches) {
-    			try {
-    				String controller =
-    						registryService.getControllerForSwitch(sw.getDpid());
-    				if (controller == null) {
-    					log.debug("Requesting control to set switch {} INACTIVE",
-    							HexString.toHexString(sw.getDpid()));
-    					registryService.requestControl(sw.getDpid(), this);
-    				}
-    			} catch (RegistryException e) {
-    				log.error("Caught RegistryException in cleanup thread", e);
-    			}
-    		}
+            if (log.isTraceEnabled()) {
+                log.trace("Checking for inactive switches");
+            }
+            // For each switch check if a controller exists in controller registry
+            for (Switch sw: switches) {
+                try {
+                    String controller =
+                            registryService.getControllerForSwitch(sw.getDpid());
+                    if (controller == null) {
+                        log.debug("Requesting control to set switch {} INACTIVE",
+                                HexString.toHexString(sw.getDpid()));
+                        registryService.requestControl(sw.getDpid(), this);
+                    }
+                } catch (RegistryException e) {
+                    log.error("Caught RegistryException in cleanup thread", e);
+                }
+            }
         }
 
-		@Override
-		public void controlChanged(long dpid, boolean hasControl) {
-			if (hasControl) {
-				log.debug("Got control to set switch {} INACTIVE", HexString.toHexString(dpid));
+        /**
+         * Second half of the switch cleanup operation. If the registry grants
+         * control of a switch, we can be sure no other instance is writing
+         * this switch to the network graph, so we can remove it now.
+         * @param dpid the dpid of the switch we requested control for
+         * @param hasControl whether we got control or not
+         */
+        @Override
+        public void controlChanged(long dpid, boolean hasControl) {
+            if (hasControl) {
+                log.debug("Got control to set switch {} INACTIVE",
+                        HexString.toHexString(dpid));
 
-				SwitchEvent switchEvent = new SwitchEvent(dpid);
-				networkGraphDiscoveryInterface.removeSwitchDiscoveryEvent(switchEvent);
-			    registryService.releaseControl(dpid);
-			}
-		}
+                SwitchEvent switchEvent = new SwitchEvent(dpid);
+                networkGraphDiscoveryInterface.
+                        removeSwitchDiscoveryEvent(switchEvent);
+                registryService.releaseControl(dpid);
+            }
+        }
     }
 
-	@Override
-	public void linkDiscoveryUpdate(LDUpdate update) {
-		LinkEvent linkEvent = new LinkEvent(update.getSrc(),
-				(long)update.getSrcPort(), update.getDst(),
-				(long)update.getDstPort());
+    @Override
+    public void linkDiscoveryUpdate(LDUpdate update) {
+        LinkEvent linkEvent = new LinkEvent(update.getSrc(),
+                (long) update.getSrcPort(), update.getDst(),
+                (long) update.getDstPort());
 
-		switch (update.getOperation()) {
-		case LINK_ADDED:
-			networkGraphDiscoveryInterface.putLinkDiscoveryEvent(linkEvent);
-			break;
-		case LINK_UPDATED:
-			// We don't use the LINK_UPDATED event (unsure what it means)
-			break;
-		case LINK_REMOVED:
-			networkGraphDiscoveryInterface.removeLinkDiscoveryEvent(linkEvent);
-			break;
-		default:
-			break;
-		}
-	}
+        switch (update.getOperation()) {
+        case LINK_ADDED:
+            networkGraphDiscoveryInterface.putLinkDiscoveryEvent(linkEvent);
+            break;
+        case LINK_UPDATED:
+            // We don't use the LINK_UPDATED event (unsure what it means)
+            break;
+        case LINK_REMOVED:
+            networkGraphDiscoveryInterface.removeLinkDiscoveryEvent(linkEvent);
+            break;
+        default:
+            break;
+        }
+    }
 
-	@Override
-	public void switchPortAdded(Long switchId, OFPhysicalPort port) {
-		PortEvent portEvent = new PortEvent(switchId, (long)port.getPortNumber());
-		networkGraphDiscoveryInterface.putPortDiscoveryEvent(portEvent);
-		linkDiscovery.RemoveFromSuppressLLDPs(switchId, port.getPortNumber());
-	}
+    @Override
+    public void switchPortAdded(Long switchId, OFPhysicalPort port) {
+        PortEvent portEvent = new PortEvent(switchId, (long) port.getPortNumber());
+        networkGraphDiscoveryInterface.putPortDiscoveryEvent(portEvent);
+        linkDiscovery.RemoveFromSuppressLLDPs(switchId, port.getPortNumber());
+    }
 
-	@Override
-	public void switchPortRemoved(Long switchId, OFPhysicalPort port) {
-		PortEvent portEvent = new PortEvent(switchId, (long)port.getPortNumber());
-		networkGraphDiscoveryInterface.removePortDiscoveryEvent(portEvent);
-	}
+    @Override
+    public void switchPortRemoved(Long switchId, OFPhysicalPort port) {
+        PortEvent portEvent = new PortEvent(switchId, (long) port.getPortNumber());
+        networkGraphDiscoveryInterface.removePortDiscoveryEvent(portEvent);
+    }
 
-	@Override
-	public void addedSwitch(IOFSwitch sw) {
-		// TODO Not very robust
-		if (!registryService.hasControl(sw.getId())) {
-			return;
-		}
+    @Override
+    public void addedSwitch(IOFSwitch sw) {
+        // TODO Not very robust
+        if (!registryService.hasControl(sw.getId())) {
+            return;
+        }
 
-		SwitchEvent switchEvent = new SwitchEvent(sw.getId());
+        SwitchEvent switchEvent = new SwitchEvent(sw.getId());
 
-		List<PortEvent> portEvents = new ArrayList<PortEvent>();
-		for (OFPhysicalPort port : sw.getPorts()) {
-			portEvents.add(new PortEvent(sw.getId(), (long)port.getPortNumber()));
-		}
-		networkGraphDiscoveryInterface
-		    .putSwitchDiscoveryEvent(switchEvent, portEvents);
+        List<PortEvent> portEvents = new ArrayList<PortEvent>();
+        for (OFPhysicalPort port : sw.getPorts()) {
+            portEvents.add(new PortEvent(sw.getId(), (long) port.getPortNumber()));
+        }
+        networkGraphDiscoveryInterface
+        .putSwitchDiscoveryEvent(switchEvent, portEvents);
 
-	    for (OFPhysicalPort port : sw.getPorts()) {
-			// Allow links to be discovered on this port now that it's
-			// in the database
-			linkDiscovery.RemoveFromSuppressLLDPs(sw.getId(), port.getPortNumber());
-	    }
-	}
+        for (OFPhysicalPort port : sw.getPorts()) {
+            // Allow links to be discovered on this port now that it's
+            // in the database
+            linkDiscovery.RemoveFromSuppressLLDPs(sw.getId(), port.getPortNumber());
+        }
+    }
 
-	@Override
-	public void removedSwitch(IOFSwitch sw) {
-		// We don't use this event - switch remove is done by cleanup thread
-	}
+    @Override
+    public void removedSwitch(IOFSwitch sw) {
+        // We don't use this event - switch remove is done by cleanup thread
+    }
 
-	@Override
-	public void switchPortChanged(Long switchId) {
-		// We don't use this event
-	}
+    @Override
+    public void switchPortChanged(Long switchId) {
+        // We don't use this event
+    }
 
-	@Override
-	public String getName() {
-		// TODO Auto-generated method stub
-		return null;
-	}
+    @Override
+    public String getName() {
+        // TODO Auto-generated method stub
+        return null;
+    }
 
-	/* *****************
-	 * IFloodlightModule
-	 * *****************/
+    /* *****************
+     * IFloodlightModule
+     * *****************/
 
-	@Override
-	public Collection<Class<? extends IFloodlightService>> getModuleServices() {
-		return null;
-	}
+    @Override
+    public Collection<Class<? extends IFloodlightService>> getModuleServices() {
+        return null;
+    }
 
-	@Override
-	public Map<Class<? extends IFloodlightService>, IFloodlightService>
-			getServiceImpls() {
-		return null;
-	}
+    @Override
+    public Map<Class<? extends IFloodlightService>, IFloodlightService>
+    getServiceImpls() {
+        return null;
+    }
 
-	@Override
-	public Collection<Class<? extends IFloodlightService>> getModuleDependencies() {
-		Collection<Class<? extends IFloodlightService>> l =
-	            new ArrayList<Class<? extends IFloodlightService>>();
+    @Override
+    public Collection<Class<? extends IFloodlightService>>
+                getModuleDependencies() {
+        Collection<Class<? extends IFloodlightService>> l =
+                new ArrayList<Class<? extends IFloodlightService>>();
         l.add(IFloodlightProviderService.class);
         l.add(ILinkDiscoveryService.class);
         l.add(IThreadPoolService.class);
@@ -216,71 +240,73 @@
         l.add(INetworkGraphService.class);
         l.add(IOnosDeviceService.class);
         return l;
-	}
+    }
 
-	@Override
-	public void init(FloodlightModuleContext context)
-			throws FloodlightModuleException {
-		floodlightProvider = context.getServiceImpl(IFloodlightProviderService.class);
-		linkDiscovery = context.getServiceImpl(ILinkDiscoveryService.class);
-		registryService = context.getServiceImpl(IControllerRegistryService.class);
-		onosDeviceService = context.getServiceImpl(IOnosDeviceService.class);
+    @Override
+    public void init(FloodlightModuleContext context)
+            throws FloodlightModuleException {
+        floodlightProvider = context.getServiceImpl(IFloodlightProviderService.class);
+        linkDiscovery = context.getServiceImpl(ILinkDiscoveryService.class);
+        registryService = context.getServiceImpl(IControllerRegistryService.class);
+        onosDeviceService = context.getServiceImpl(IOnosDeviceService.class);
 
-		networkGraphService = context.getServiceImpl(INetworkGraphService.class);
-	}
+        networkGraphService = context.getServiceImpl(INetworkGraphService.class);
+    }
 
-	@Override
-	public void startUp(FloodlightModuleContext context) {
-		floodlightProvider.addOFSwitchListener(this);
-		linkDiscovery.addListener(this);
-		onosDeviceService.addOnosDeviceListener(this);
+    @Override
+    public void startUp(FloodlightModuleContext context) {
+        floodlightProvider.addOFSwitchListener(this);
+        linkDiscovery.addListener(this);
+        onosDeviceService.addOnosDeviceListener(this);
 
-		networkGraph = networkGraphService.getNetworkGraph();
-		networkGraphDiscoveryInterface =
-				networkGraphService.getNetworkGraphDiscoveryInterface();
+        networkGraph = networkGraphService.getNetworkGraph();
+        networkGraphDiscoveryInterface =
+                networkGraphService.getNetworkGraphDiscoveryInterface();
 
-		// Run the cleanup thread
-		String enableCleanup =
-				context.getConfigParams(this).get(ENABLE_CLEANUP_PROPERTY);
-		if (enableCleanup != null && enableCleanup.toLowerCase().equals("false")) {
-			cleanupEnabled = false;
-		}
+        // Run the cleanup thread
+        String enableCleanup =
+                context.getConfigParams(this).get(ENABLE_CLEANUP_PROPERTY);
+        if (enableCleanup != null
+                && enableCleanup.equalsIgnoreCase("false")) {
+            cleanupEnabled = false;
+        }
 
-		log.debug("Cleanup thread is {}enabled", (cleanupEnabled)? "" : "not ");
+        log.debug("Cleanup thread is {}enabled", (cleanupEnabled) ? "" : "not ");
 
-		if (cleanupEnabled) {
-			IThreadPoolService threadPool =
-					context.getServiceImpl(IThreadPoolService.class);
-			cleanupTask = new SingletonTask(threadPool.getScheduledExecutor(),
-					new SwitchCleanup());
-			// Run the cleanup task immediately on startup
-			cleanupTask.reschedule(0, TimeUnit.SECONDS);
-		}
-	}
+        if (cleanupEnabled) {
+            IThreadPoolService threadPool =
+                    context.getServiceImpl(IThreadPoolService.class);
+            cleanupTask = new SingletonTask(threadPool.getScheduledExecutor(),
+                    new SwitchCleanup());
+            // Run the cleanup task immediately on startup
+            cleanupTask.reschedule(0, TimeUnit.SECONDS);
+        }
+    }
 
-	@Override
-	public void onosDeviceAdded(OnosDevice device) {
-		log.debug("Called onosDeviceAdded mac {}", device.getMacAddress());
+    @Override
+    public void onosDeviceAdded(OnosDevice device) {
+        log.debug("Called onosDeviceAdded mac {}", device.getMacAddress());
 
-		SwitchPort sp = new SwitchPort(device.getSwitchDPID(), (long)device.getSwitchPort());
-		List<SwitchPort> spLists = new ArrayList<SwitchPort>();
-		spLists.add(sp);
-		DeviceEvent event = new DeviceEvent(device.getMacAddress());
-		event.setAttachmentPoints(spLists);
-		event.setLastSeenTime(device.getLastSeenTimestamp().getTime());
-		if(device.getIpv4Address() != null) {
-			InetAddress ip = InetAddresses.fromInteger(device.getIpv4Address());
-			event.addIpAddress(ip);
-		}
-		// Does not use vlan info now.
+        SwitchPort sp = new SwitchPort(device.getSwitchDPID(),
+                (long) device.getSwitchPort());
+        List<SwitchPort> spLists = new ArrayList<SwitchPort>();
+        spLists.add(sp);
+        DeviceEvent event = new DeviceEvent(device.getMacAddress());
+        event.setAttachmentPoints(spLists);
+        event.setLastSeenTime(device.getLastSeenTimestamp().getTime());
+        if (device.getIpv4Address() != null) {
+            InetAddress ip = InetAddresses.fromInteger(device.getIpv4Address());
+            event.addIpAddress(ip);
+        }
+        // Does not use vlan info now.
 
-		networkGraphDiscoveryInterface.putDeviceDiscoveryEvent(event);
-	}
+        networkGraphDiscoveryInterface.putDeviceDiscoveryEvent(event);
+    }
 
-	@Override
-	public void onosDeviceRemoved(OnosDevice device) {
-		log.debug("Called onosDeviceRemoved");
-		DeviceEvent event = new DeviceEvent(device.getMacAddress());
-		networkGraphDiscoveryInterface.removeDeviceDiscoveryEvent(event);
-	}
+    @Override
+    public void onosDeviceRemoved(OnosDevice device) {
+        log.debug("Called onosDeviceRemoved");
+        DeviceEvent event = new DeviceEvent(device.getMacAddress());
+        networkGraphDiscoveryInterface.removeDeviceDiscoveryEvent(event);
+    }
 }