Adding missing files under onlab-netty
diff --git a/utils/netty/src/main/java/org/onlab/netty/MessagingService.java b/utils/netty/src/main/java/org/onlab/netty/MessagingService.java
new file mode 100644
index 0000000..ebad442
--- /dev/null
+++ b/utils/netty/src/main/java/org/onlab/netty/MessagingService.java
@@ -0,0 +1,41 @@
+package org.onlab.netty;
+
+import java.io.IOException;
+
+/**
+ * Interface for low level messaging primitives.
+ */
+public interface MessagingService {
+ /**
+ * Sends a message asynchronously to the specified communication end point.
+ * The message is specified using the type and payload.
+ * @param ep end point to send the message to.
+ * @param type type of message.
+ * @param payload message payload.
+ * @throws IOException
+ */
+ public void sendAsync(Endpoint ep, String type, Object payload) throws IOException;
+
+ /**
+ * Sends a message synchronously and waits for a response.
+ * @param ep end point to send the message to.
+ * @param type type of message.
+ * @param payload message payload.
+ * @return a response future
+ * @throws IOException
+ */
+ public <T> Response<T> sendAndReceive(Endpoint ep, String type, Object payload) throws IOException;
+
+ /**
+ * Registers a new message handler for message type.
+ * @param type message type.
+ * @param handler message handler
+ */
+ public void registerHandler(String type, MessageHandler handler);
+
+ /**
+ * Unregister current handler, if one exists for message type.
+ * @param type message type
+ */
+ public void unregisterHandler(String type);
+}