public function receiveMeta($metaData, $source)
    {
        $this->streamingSource = $source;
        $this->newMeta = $this->metaData = $metaData;
        $func = Util::get($this->params, '{meta}', null);
        if (is_callable($func)) {
            $this->newMeta = $func($metaData);
        }
    }