I want to implement a real-time paintboard that is shared.

I'm going to work on a school project and I'm going to implement a paintboard that is shared with others in real time!

It's kind of similar to the game Catch Mind.

Multiple users can connect and draw on one paintboard (whiteboard) at the same time, load a photo file stored locally on that paintboard, and implement the ability to save the finished paintboard on the server. It's going to be implemented on the web.

I'm trying to work with either node.js or jsp as a developable language, but I'd appreciate it if you could give me keywords or hints about which language to implement and how to implement these functions