protected function getResourceParameter()
    {
        if (! $this->hasRequestParameter(self::RESOURCE_PARAMETER)) {
            throw new \common_exception_MissingParameter(self::RESOURCE_PARAMETER, __CLASS__);
        }

        $uri = $this->getRequestParameter(self::RESOURCE_PARAMETER);
        if (empty($uri) || !common_Utils::isUri($uri)) {
            throw new \common_exception_MissingParameter(self::RESOURCE_PARAMETER, __CLASS__);
        }

        return $this->getResource($uri);
    }