Added a messaging service implementation on top of IOLoop. Added ability to easily switch between netty and io loop (default is netty)

Change-Id: Id9af0756bf0a542f832f3611b486b2ac680b91e4
diff --git a/core/api/src/main/java/org/onosproject/store/cluster/messaging/Endpoint.java b/core/api/src/main/java/org/onosproject/store/cluster/messaging/Endpoint.java
new file mode 100644
index 0000000..2ac50df
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/store/cluster/messaging/Endpoint.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright 2014-2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.store.cluster.messaging;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.util.Objects;
+
+import org.onlab.packet.IpAddress;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * Representation of a TCP/UDP communication end point.
+ */
+public final class Endpoint {
+
+    private final int port;
+    private final IpAddress ip;
+
+    public Endpoint(IpAddress host, int port) {
+        this.ip = checkNotNull(host);
+        this.port = port;
+    }
+
+    public IpAddress host() {
+        return ip;
+    }
+
+    public int port() {
+        return port;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("ip", ip)
+                .add("port", port)
+                .toString();
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(ip, port);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        Endpoint that = (Endpoint) obj;
+        return Objects.equals(this.port, that.port) &&
+               Objects.equals(this.ip, that.ip);
+    }
+}