code: def handle_invocation(self, message):
          
          req_id = message.request_id
          reg_id = message.registration_id
          if reg_id in self._registered_calls:
              handler = self._registered_calls[reg_id][REGISTERED_CALL_CALLBACK]
              invoke = WampInvokeWrapper(self,handler,message)
              invoke.start()
          else:
              error_uri = self.get_full_uri('error.unknown.uri')
              self.send_message(ERROR(
                  request_code = WAMP_INVOCATION,
                  request_id = req_id,
                  details = {},
                  error =error_uri
              ))
docs: Passes the invocation request to the appropriate
              callback.