Websocket server using Jetty/Cometd

So I just wrote up a Websocket server using CometD/Bayeux. It’s a ridiculously simple app – but went quite a long way in helping to understand the nitty gritties with putting up a Websocket server and CometD/Bayeux. Thought that I’ll put it up for reference – should help in getting a leg up on getting started with CometD.

The sample’s up on github at https://github.com/raghur/rest-websocket-sample

Here’s how to go about running it:

1. clone the repo above
2. run mvn jetty:run
3. Now browse to http://localhost:8080 to see the front page

4. There are two parts to the app

   1. A RESTful API at http://localhost:8080/user/{name} – hypothetical user info – get retrieves a user, put creates a user and delete obviously deletes the user.
   2. The websocket server at localhost:8080/cometd has a broadcast channel at /useractivity which receives events whenever a user is added/deleted. The main page at http://localhost:8080 has a websocket client that updates the page with the user name whenever a user is added or removed.

And here’s the nuts and bolts:

1. BayeuxInitializer – initializes the Bayeux Service and the EventBroadcaster. Puts the EventBroadcaster in the servlet context from where the RESTful service can pick it up to broadcast.
2. EventBroadcaster – creates a broadcast channel in the ctor. Provides APIs to publish messages on this channel.
3. HelloService – basic echo service taken from Maven archetype
4. MyResource – the RESTful resource which responds to GET/PUT/DELETE – nothing major here. If a user is added or deleted, then it pushes a message on the broadcast channel by getting the EventBroadcaster instance from the servlet context.

It’s about as simple as you can get (beyond a Hello world or a chat example). Specifically, I wanted a sample where back end changes can be pushed to clients.

Yahoo! mail fixed for Firefox 3 beta 2

Used to get an error on opening Yahoo mail beta in Firefox 3 beta 2 – and had to switch to the plain ‘ole yahoo mail. Here’s the bug report

Was pleasantly surprised today morning to see that Yahoo! mail beta now works properly in FF3b2. Thanks!