Added rest API to look into the topology events map for debugging

Change-Id: I15f95fa7184bf6e087926c8cbc49db2dd6f65a5a
diff --git a/src/main/java/net/onrc/onos/datagrid/web/GetNGEventsResource.java b/src/main/java/net/onrc/onos/datagrid/web/GetNGEventsResource.java
new file mode 100644
index 0000000..20efa68
--- /dev/null
+++ b/src/main/java/net/onrc/onos/datagrid/web/GetNGEventsResource.java
@@ -0,0 +1,41 @@
+package net.onrc.onos.datagrid.web;
+
+import java.util.Collection;
+
+import net.onrc.onos.datagrid.IDatagridService;
+import net.onrc.onos.datagrid.IEventChannel;
+import net.onrc.onos.ofcontroller.networkgraph.TopologyEvent;
+import net.onrc.onos.ofcontroller.networkgraph.TopologyManager;
+
+import org.restlet.resource.Get;
+import org.restlet.resource.ServerResource;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class GetNGEventsResource extends ServerResource {
+
+	public static final Logger log = LoggerFactory.getLogger(GetNGEventsResource.class);
+	
+	@Get("json")
+	public String retrieve() {
+		IDatagridService datagridService = 
+				(IDatagridService) getContext().getAttributes().
+				get(IDatagridService.class.getCanonicalName());
+		
+		
+		log.debug("Get network graph events");
+		
+		IEventChannel<byte[], TopologyEvent> channel = datagridService.createChannel(TopologyManager.EVENT_CHANNEL_NAME, 
+				byte[].class, TopologyEvent.class);
+		
+		Collection<TopologyEvent> entries = channel.getAllEntries();
+		
+		String result = "";
+		for (TopologyEvent event : entries) {
+			result += event.toString() + "\n";
+		}
+		
+		return result;
+	}
+
+}