Callback

src/main/java/com/google/code/gossip/event/GossipState.java

@@ -0,0 +1,10 @@
+package com.google.code.gossip.event;
+
+public enum GossipState {
+  UP("up"), DOWN("down");
+  private String state;
+  
+  private GossipState(String state){
+    this.state = state;
+  }
+}