public function forSubscription($subscriptionId)
    {
        $service = $this->getService();

        // events for a subscription
        $response = $service->request('subscriptions/' . $subscriptionId . '/events', 'GET', NULL, $this->getParams());

        $responseArray = $this->getResponseArray($response);

        if (!$this->isError()) {
            $this->_data = $this->_normalizeResponseArray($responseArray);
        } else {
            $this->_data = array();
        }

        return $this;
    }