Implementing a chat server as a WebService

Question

I have a school project in which I have to implement a chat application, whose server will be a java web service.

The problem is that I've always thought of a web service as a way of calling remote functions, and I have no idea how to keep a "session" active on the web service, nor how to keep track of all the people currently in chat, rooms etc.

Answer 1

To the best of my knowledge, a chat server is supposed to know its clients after an initial connection, and send every client message to all clients. This definitely calls for some sort of session maintenance. I think the right way to do this is as follows:

1. Client calls web service 'handshake' and provides some minimal identification details.
2. Server returns an acknowledgment that includes a unique client identifier.
3. Client calls web service 'message' and sends a new message, together with its identifier.
4. Server identifies client by the identifier, distributes message to all clients.

I'm not really sure how the message distribution should work, as web services are essentially a pull-service and not push. Perhaps the client should expose its own web service for the server to call.

Hope this helps,

Yuval =8-)

Answer 2

You could consider implementing a COMET solution. This will effectively give you push communication, thus eliminating latency, a VERY nice feature for a chat application.

If you want to go for the gold, consider implementing more advanced features:

• spell check
• URLs/email addresses converted to links automatically
• separate chat rooms
• moderator functions (terminate chat, kick user)
• event info like "User is typing..."
• statuses (available, busy, away...)
• avatars
• ...