public function publish_http_stream($channel, $http_stream, $id = null, $prev_id = null)
    {
        if (is_string($http_stream)) {
            $http_stream = new HttpStreamFormat($http_stream);
        }
        $item = new \PubControl\Item($http_stream, $id, $prev_id);
        parent::publish($channel, $item);
    }