public static function FormatRequestData(array $data, $outputType)
 {
     $requestData = "";
     switch ($outputType) {
         case "xml":
             $requestData = urlencode('<?xml version="1.0" encoding="UTF-8"?><request>' . XmlHelper::array2xml($data) . '</request>');
             break;
         case "json":
             $requestData = json_encode($data);
             break;
     }
     return $requestData;
 }