public function getActionDescription($controllerClassName, $actionName) {

        if (!class_exists($controllerClassName) || !method_exists($controllerClassName, $actionName)) {
            throw new ActionNotFoundException('Unknown '.$controllerClassName.'@'.$actionName);
        }

        $reflector = new \ReflectionMethod($controllerClassName, $actionName);
        return new ActionDescription($reflector);
    }