protected function _loadRequestMethod()
    {
        if($this->_requestMethod !== NULL) return;

        if(!key_exists('REQUEST_METHOD', $_SERVER)) {
            throw new Exception("Request method unknown");
        }

        $method = strtoupper($_SERVER['REQUEST_METHOD']);

        if (in_array($method, array('GET', 'POST', 'PUT', 'DELETE', 'PATCH'))) {
            $this->_requestMethod = $method;
        } else {
            throw new Exception("Request method ($method) invalid");
        }
    }