public function getWriterByName($fp, $writerName)
    {
        $method = 'get' . $writerName;
        if(method_exists($this->getWriterFactory(), $method)) {
            return $this->getWriterFactory()->$method($fp);
        } else {
            throw new \InvalidArgumentException('writer not found: ' . $writerName);
        }
    }