A scenario for the connection would be adding storage to connection for example to save associated data... WebSocket is used for communication and a json based

A scenario for the connection would be adding storage to connection for example to save associated data... WebSocket is used for communication and a json based protocol is used by default, but to save bandwidth, the protocol can be exchanged (i.e. there is an example using bson to transmit data instead). So the protocol on top of websockets is interchangeable.