private function getChannelId()
 {
     if ($this->channel_id != "") {
         return $this->channel_id;
     }
     $token = $this->getCurrentClientToken();
     $webhooksSrvc = new WebhooksService($this->base_url, $token);
     $channel = new Channel("MIM", "application/json", 1);
     $rsp = null;
     try {
         $rsp = $webhooksSrvc->createNotificationChannel($channel);
         $this->channel_id = $rsp->getChannel()->getChannelId();
         return $this->channel_id;
     } catch (ServiceException $ex) {
         $exObjectParts = explode(":4", $ex->getMessage());
         $exObject = json_decode($exObjectParts[0]);
         if (isset($exObject->RequestError) && isset($exObject->RequestError->MessageId) && $exObject->RequestError->MessageId == "POL1001") {
             $this->channel_id = explode(":", $exObject->RequestError->Variables)[1];
             return $this->channel_id;
         }
         throw $ex;
     }
 }