public function getService($type)
    {
        if (!isset($this->services[$type])) {
            if (!file_exists(__DIR__ . '/' . $type . '/Service.php')) {
                throw new InvalidServiceTypeException('No service for type ' . $type);
            }
            $classname = __NAMESPACE__ . '\\' . $type . '\Service';
            $this->services[$type] = new $classname($this);
        }
        return $this->services[$type];
    }