Attaches a service for hosting
        :param http_service: A HTTPService instance

def attach_http_service(cls, http_service: HTTPService):
        """ Attaches a service for hosting
        :param http_service: A HTTPService instance
        """
        if cls._http_service is None:
            cls._http_service = http_service
            cls._set_bus(http_service)
        else:
            warnings.warn('HTTP service is already attached')