Squashed commit of the following:

commit e9604083c5374bf5eac889e82cf54bb0b22ef763
Author: Naoki Shiota <n-shiota@onlab.us>
Date:   Wed Oct 23 11:51:00 2013 -0700

    Refactored NetworkGraphPublisher and related modules to be ready for implementing event notification.
diff --git a/src/main/java/net/onrc/onos/ofcontroller/core/ILinkStorage.java b/src/main/java/net/onrc/onos/ofcontroller/core/ILinkStorage.java
index ce2379b..483fbda 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/core/ILinkStorage.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/core/ILinkStorage.java
@@ -15,26 +15,27 @@
 	/*
 	 * Generic operation method
 	 */
-	public void update(Link link, LinkInfo linkinfo, DM_OPERATION op);
+	public boolean update(Link link, LinkInfo linkinfo, DM_OPERATION op);
 	
 	/*
      * Link creation
      */
-	public void addLink(Link link);
-	public void addLinks(List<Link> links);
+	public boolean addLink(Link link);
+	public boolean addLink(Link link, LinkInfo linfo);
+	public boolean addLinks(List<Link> links);
 	
 	/*
 	 * Link deletion
 	 */
-	public void deleteLink(Link link);
-	public void deleteLinks(List<Link> links);
+	public boolean deleteLink(Link link);
+	public boolean deleteLinks(List<Link> links);
 
 	/*
 	 * Utility method to delete links associated with dpid and port 
 	 * If only dpid is used, All links associated for switch are removed
 	 * Useful for port up/down and also switch join/remove events
 	 */ 
-	public void deleteLinksOnPort(Long dpid, short port);
+	public boolean deleteLinksOnPort(Long dpid, short port);
 
 	/*
 	 * Get Links from Storage