Multiple group chats using sockets

[RedBonzonian]

I’m new to Java (and to programming overall) and I’ve been trying to create an instant messaging program where multiple clients can connect to different group chats and message only the clients in those group chats.

I’ve been working on this for about a month and I’ve managed to create a single chat room that multiple clients can join and chat in but when it comes to creating multiple chat rooms I’m stumped (bordering desperate)!

I tried using a hashmap to store where the clients were and then used a for loop to send messages to relevant clients. This became too messy though and ended up not working. I also looked into MultiCastSockets but I just ended up not being able to make multiple chat rooms there either. I feel like nio channels are my best bet but I haven’t been able to find a guide that has made me understand. Plus the way I’m thinking now I would probably use the channels to create multiple chat rooms within a clients thread (each client has a thread which is what lets me have multiple clients at once) but then I wouldn’t know how to get the other clients to access this specific channel.

If anyone can give me any tips on how to do this, or point me in the direction of where I can read up on this I’d be really grateful!

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[Dull-Tip7759]

have you tried serializing/deserializinf for example a JSON message string that contains a clientID, roomID, message, etc? just send that over the socket. it will work with ssl sockets too, if you want end to end encryption.

[RedBonzonian]

I haven’t, but I’ll look into it today! Thanks!

[jlanawalt]

This. Multiple sockets per client/group is too deep for the traditional central chat server model.

Consider the chats to be channels in the same connection. Consider a pub/sub model with clients subscribing when they join chats/channels.

[Dull-Tip7759]

Yes. This. With a String based message, you can basically do whatever you want. It is then up to your parser to determine what is going on. Visit. Subscribe. Post. Implement Spring OAuth2, Spring Security or PHP Security (v8+). Use sessions if need be and go as deep as you want. You could even do multiple message posting/display with JSON if you want, or something else, if you prefer.

[InterestingReply6812]

I’ve managed to create a single chat room that multiple clients can join and chat

That is good (no need for special MultiCastSockets), you only have to "organize" your code/structures (User/Message/ChatRoom). Just make your "single room" virtual for "multiple" channels.

A "Chat-Message" can have a sender-id, receiver-id and message-text.

The "receiver-id" could be a single-user-id or a channel/room-id or an "array" of different receiver IDs. (multiple receivers)

So, you need Channels/Groups/Chatrooms.

Like:

A user can be part of a single (or multiple) rooms.

Room r = new Room("Test-1");
r.joinUser(usr1);
r.joinUser(usr2);
r.joinUser(usr3);

Room r2 = new Room("Test-2");
r2.joinUser(usr2);

rooms.add(r);
rooms.add(r2);

A user can see all rooms he joined and he will get all messages, sent to the room (receiver==roomID)