public function getRealtimeData()
    {
        $this->validateViewId();

        $this->setMetrics('rt:activeUsers');

        $data = $this->service->data_realtime->get(
            $this->viewId,
            $this->getMetricsAsString(),
            $this->getOptions()
        );

        return $data->toSimpleObject()->totalsForAllResults;
    }