Chat Sever using WebSocket in GlassFish 4 (TOTD #207)

A canonical example of using WebSocket is a chat server. This TipOf The Day (TOTD) will share the code for building exactly that!

The complete code in this TOTD can be downloaded here and runs on GlassFish 4 b77.

Here is the code for the Chat Server built as a WebSocket endpoint:

@WebSocketEndpoint("/websocket")
public class ChatEndpoint {
 private static final Set<Session> peers = Collections.synchronizedSet(new HashSet<Session>());

 @WebSocketOpen
 public void onOpen(Session peer) {
 peers.add(peer);
 }

 @WebSocketClose
 public void onClose(Session peer) {
 peers.remove(peer);
 }

 @WebSocketMessage
 public void message(String message, Session client) throws IOException, EncodeException {
 for (Session peer : peers) {
 peer.getRemote().sendObject(message);
 }
 }
}

In this code:

• Lifecycle callbacks manage the coordinates of the connecting clients
• message method receives all the messages sent by the client and then transmits to all the connected clients.
  

Simple, isn't it ?

You can use a trivial JavaScript to exchange messages between two browsers. A chat session between two Chrome and Firefox is shown below:



Download the source code and run it in GlassFish 4 b77.