protected function processRequest($method, $uri, $params = null, $body = null)
    {
        $methodString = $this->getMethod($method);

        if (method_exists($this, $methodString)) {
            return $this->$methodString($method, $uri, $params, $body);
        } else {
            throw new InvalidRequestMethodException("request method '{$method}' not implemented");
        }
    }