This is an exercise in building a Java server and using the HTTP protocol for client-server communication.
If you want to download it and see how it works, you can simply clone the seed repository.
The seed is 2 in 1: A Java webserver that hosts a page from which you can download the chat client, and a Java chatserver, which listens for http requests from the chat clients, connects, and responds (redistributes) messages back to the appropriate online clients, until a close command is sent, which maked the server close the connection with that client.
This client-server interaction happens via a custom protocol which builds on top of the HTTP protocol. You can observe this protocol in the file 'ProtocolStrings'.
Run the 2 .bat files to start the web and chat server. Before doing so, remember to change the IP to "localhost".