def METHOD_NAME(self, data, plugin=None):
    """
    Sends a message to the client.the
    :param data: message object
    :param plugin: routing ID (this endpoint's ID if not specified)
    :type  plugin: str
    """
    self.context.worker.send_to_upstream({
        'type': 'socket',
        'message': {
            'plugin': plugin or self.plugin,
            'data': data,
        },
    })