Device Anti-Entropy

- create Advertisement
- handler for Advertisement
- register handler, background thread to send advertisement

Change-Id: I99e8a7d68747970c34b3c25c6d0489769d251446
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/device/impl/GossipDeviceStoreMessageSubjects.java b/core/store/dist/src/main/java/org/onlab/onos/store/device/impl/GossipDeviceStoreMessageSubjects.java
index 5272182..3168368 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/device/impl/GossipDeviceStoreMessageSubjects.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/device/impl/GossipDeviceStoreMessageSubjects.java
@@ -2,6 +2,7 @@
 
 import org.onlab.onos.store.cluster.messaging.MessageSubject;
 
+// TODO: add prefix to assure uniqueness.
 /**
  * MessageSubjects used by GossipDeviceStore peer-peer communication.
  */
@@ -14,4 +15,8 @@
     public static final MessageSubject DEVICE_REMOVED = new MessageSubject("peer-device-removed");
     public static final MessageSubject PORT_UPDATE = new MessageSubject("peer-port-update");
     public static final MessageSubject PORT_STATUS_UPDATE = new MessageSubject("peer-port-status-update");
+
+    public static final MessageSubject DEVICE_ADVERTISE = new MessageSubject("peer-device-advertisements");
+    // to be used with 3-way anti-entropy process
+    public static final MessageSubject DEVICE_REQUEST = new MessageSubject("peer-device-request");
 }