CM10228 Chat Application

Now that you know how to make clients and servers, and have them both threaded, the only thing left to do is to let the multiple clients interact with each other. This is actually reasonably simple, and is just pure Java. You already know all the networking and all the threading that you need to know to do this. And in fact, your clients from the previous section should be already capable of sending and receiving messages in this chat program (although you might want to add a prompt to distinguish between what you are typing and what came from the server).

Do this:

Task:

Create a server which accepts multiple client connections. When a message is received from a client, broadcast this message to all the other clients (and the sender if you wish).

If you have time, try one or more of these bonus objectives:

When a client connects, ask for their name. Now whenever a client sends a message, prefix their name to the message that is broadcast.

Can you deal with clients connecting and disconnecting mid-way through the conversation?

Come up with a protocol for your chat room. Make your server announce when people join or leave the conversation, using some identifier so everyone knows the message is from the server.

You might want to stop people abusing your chat room

Add a character limit to each message (prevent anything over this being sent, and warn the user from the server that it wasn't sent).

Disconnect users who try to send too many messages in a short time, or who keep trying to send messages that are too long.

In summary: you have learned how to spawn threads that go and do jobs at the same time as the one that spawned it. You have learned how to send simple messages over a network in a client-server model, using Socket and ServerSocket. You have also learned how to use threading to improve the client and the server of your application.

CM10228 / Programming Ib: Lab 2

Concurrency and Networking: Chat Application

Do this: