$options = array('indent' => '     ', 'addDecl' => false, "defaultTagName" => "user_message", XML_SERIALIZER_OPTION_RETURN_RESULT => true);
                    $serializer = new XML_Serializer($options);
                    Rest::sendResponse(200, $serializer->serialize($userMessageArray), 'application/xml');
                }
            }
        } else {
            Rest::sendResponse(204);
        }
        break;
    case 'post':
        try {
            $message = new Message();
            $data_message = $http->getRequestVars();
            $messageObject = initObject($data_message, $message, true);
            if (!emptyObject($messageObject)) {
                $userMapper = new UserMapper();
                if ($userMapper->sendMessage($messageObject)) {
                    Rest::sendResponse(200);
                }
            } else {
                throw new InvalidArgumentException('Need arguments to POST data !');
            }
        } catch (InvalidArgumentException $e) {
            print $e->getMessage();
            exit;
        }
        break;
    default:
        Rest::sendResponse(501);
        break;
}