def _bind_service(package_name, cls_name, binder=Injected):
        """Bind service to application injector.

        :param package_name: service package
        :type package_name: str
        :param cls_name: service class
        :type cls_name: str
        :param binder: current application binder, injected
        :type binder: Binder
        """
        module = importlib.import_module(package_name)
        cls = getattr(module, cls_name)

        binder.bind(
            cls,
            to=binder.injector.create_object(cls),
            scope=singleton
        )
        logging.debug("Created {0} binding.".format(cls))