Implementing a IM platform in Java

Question

If creating an IM platform in Java, which would be a better way to implement communications between the clients and server? I was thinking either RMI or just a socket connection...

Advice please,

Thanks

Answer 1

I would use straight socket connection, using a well known protocol such as XMPP. You can use a library (like smack) to avoid implementing the whole protocol yourself.

The main advantage of XMPP over RMI or your self-made protocol is that is a well established protocol used for exactly that purpose: IM.

Some chat services already using XMPP include Google Chat (GTALK) and Facebook.

Answer 2

I already did this using Smack API, using XMPP protocol.

Answer 3

CometD has been specifically designed for use cases such as Chatrooms. Differently from other protocols, it works over HTTP port 80, which means (nearly) no hassles with Firewalls.

Listen to a recent podcast with Greg Wilkins about the project, which goes into some details of issues with implementing Chatrooms and how it gets handled by CometD.

I believe there is a Java client for CometD if you need to have client on both sides of conversation (normally frontend is JavaScript).