private function _blockUntilAsyncFinish(AsynchronousOperationResult $requestInfo)
    {
        $status = null;

        do {
            sleep(5);
            $result = $this->_proxy->getOperationStatus($requestInfo);
            $status = $result->getStatus();
        } while (OperationStatus::IN_PROGRESS == $status);

        if (OperationStatus::SUCCEEDED != $status) {
            throw $result->getError();
        }
    }