BroadcastMessage send broadcast message to channel and record stats.

HandleWebSocketCommand used to register command and handler.

InitWebSocket start websocket.

ServeWs handles websocket requests from the peer.

ConfigMessage used to send configuration.

PrivateMessage means message is 1 to 1.

PublicMessage means broadcast message.

Hub maintains the set of active connections and broadcasts messages to the connections.

WebsocketConnection is an middleman between the websocket connection and the hub.

MsgType is the type of different message.

WebsocketHandlerFunc define the func to handle websocket.