protected function execute()
    {
        if ($this->url === null) {
            throw new CurlException('You have to provide an URL for the CurlRequest');
        }

        $ch = curl_init($this->url);
        curl_setopt_array($ch, $this->options);

        $this->content = curl_exec($ch);
        $this->infos   = curl_getinfo($ch);
        $this->error   = curl_error($ch);

        curl_close($ch);

        return $this->content;
    }