protected function writeLog($operation, $info_to_log)
    {
        $serverName = php_uname('n');

        if (isset($_SERVER['SERVER_NAME'])) {
            $serverName = $_SERVER['SERVER_NAME'];
        }

        $fh = fopen($this->mpay24Sdk->getMpay24LogPath(), 'a+') or die("can't open file");
        $MessageDate = date("Y-m-d H:i:s");
        $Message     = $MessageDate . " " . $serverName . " Mpay24 : ";
        $result      = $Message . "$operation : $info_to_log\n";
        fwrite($fh, $result);
        fclose($fh);
    }