public function convertLocalFile($inputFile = '', $outputFilename = '', $outputFormat = '')
    {
        //check whether file is set or not
        if ($inputFile == '')
            throw new Exception('No file name specified');

        if ($outputFormat == '')
            throw new Exception('output format not specified');


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

        if (!file_exists($inputFile)) {
            throw new Exception('input file doesnt exist.');
        }


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

        $responseStream = Utils::uploadFileBinary($signedURI, $inputFile, 'xml');

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

        if ($v_output === '') {
            if ($outputFormat == 'html') {
                $saveFormat = 'zip';
            } else {
                $saveFormat = $outputFormat;
            }

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