Does anybody know of any free implementations or libraries for multiplayer online game lobbies (such as those at funorb.com or yahoo games)? I had a bit of a Google but couldn't find much.
Alternatively, any advice for the engineering of such a system would be welcome.
My advice is find yourself a good NIO framework or roll your own. Start with NIO sockets so you don't have to rewrite it later. :)
NIO doesn't have sockets as far as I can see. Nor support for Object input/output. I don't see the advantage in this situation.
"NIO doesn't have sockets as far as I can see."
It does: SocketChannel
"I don't see the advantage in this situation."
Just depends how many connections you plan to have at once? With blocking sockets it requires a thread per connection. With Non-blocking sockets you only need one (or a few) threads to handle all connections. If it's under a hundred connections, then you probably don't need it. :)
How would you get a SocketChannel by accept()ing incoming connections?
I personally found this tutorial helpful:
Rox Java NIO Tutorial
Thanks for the info, but I'm not expecting more than a few tens of simultaneous connections.