diff --git a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/INetworkGraphService.java b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/INetworkGraphService.java
index 318c0f7..5d94f65 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/INetworkGraphService.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/INetworkGraphService.java
@@ -11,11 +11,14 @@
 	 * @return
 	 */
     public NetworkGraph getNetworkGraph();
-    
+
+    public void registerNetworkGraphListener(INetworkGraphListener listener);
+    public void deregisterNetworkGraphListener(INetworkGraphListener listener);
+
     /**
      * Allows a module to get a reference to the southbound interface to
      * the network graph.
-     * TODO Figure out how to hide the southbound interface from 
+     * TODO Figure out how to hide the southbound interface from
      * applications/modules that shouldn't touch it
      * @return
      */