HijackIfPossible calls Hijack() on the given http.ResponseWriter if it implements http.Hijacker interface, which is required for net/http/httputil/reverseproxy to handle connection upgrade/switching protocol.

NewDurableConnection creates a new websocket connection, that passes incoming messages to the given message channel.

NewDurableSendingConnection creates a new websocket connection that can only send messages to the endpoint it connects to.

ErrConnectionNotEstablished is returned by methods that need a connection but no connection is already created.

ManagedConnection represents a websocket connection.