The classes autobahn.websocket.WebSocketServerProtocol and autobahn.websocket.WebSocketServerFactory are the base classes you derive from to implement WebSocket servers.
To create your actual server, you need a factory with the protocol attribute set to your protocol.
You may either use autobahn.websocket.WebSocketServerFactory directly and without modification or you can derive from that class when you want to extend it’s behavior i.e. with state that is available for all client connections.
Usually, you implement your WebSocket server by creating a protocol that derives from autobahn.websocket.WebSocketServerProtocol.
This class in turn derives from autobahn.websocket.WebSocketProtocol, which is where you find all the callbacks and methods.