This is a realtime chat built with Go
First, we have the hub running on a separate goroutine which is the central place that manages different channels and contains a map of rooms. The hub has a Register and an Unregister channel to register/unregister clients, and a Broadcast channel that receives a message and broadcasts it out to all the other clients in the same room.
A room is initially empty. Only when a client hits the /ws/joinRoom endpoint, that will create a new client object in the room and it will be registered through the hub's Register channel.
Each client has a writeMessage and a readMessage method. readMessage reads the message through the client's websocket connection and send the message to the Broadcast channel in the hub, which will then broadcast the message out to every client in the same room. The writeMessage method in each of those clients will write the message to its websocket connection, which will be handled on the frontend side to display the messages accordingly.