public function convertByUrl($url = '', $format = '', $outputFilename = '')
    {
        //check whether file is set or not
        if ($url == '')
            throw new Exception('Url not specified');

        $strURI = Product::$baseProductUri . '/pdf/convert?url=' . $url . '&format=' . $format;

        $signedURI = Utils::sign($strURI);

        $responseStream = Utils::processCommand($signedURI, 'PUT', '', '');

        $v_output = Utils::validateOutput($responseStream);

        if ($v_output === '') {
            if ($this->saveFormat == 'html') {
                $saveFormat = 'zip';
            } else {
                $saveFormat = $this->saveFormat;
            }

            $outputPath = AsposeApp::$outPutLocation . Utils::getFileName($outputFilename) . '.' . $format;
            Utils::saveFile($responseStream, $outputPath);
            return $outputPath;
        } else {
            return $v_output;
        }
    }