def stopService(self):
        """
        Gracefully stop the service.

        Returns:
            defer.Deferred: a Deferred which is triggered when the service has
                finished shutting down.
        """
        self._service.factory.stopTrying()
        yield self._service.factory.stopFactory()
        yield service.MultiService.stopService(self)
Gracefully stop the service.

        Returns:
            defer.Deferred: a Deferred which is triggered when the service has
                finished shutting down.