Subscription query request message
With either package in the BlackBerry® Push Service, you can request information about the status of a subscriber. The subscription query is an extension to the PAP standard, and it is available to all content providers who use the BlackBerry Push Service.
With a <subscriptionquery-message> request, you can explicitly poll the BlackBerry Push Service database to identify which BlackBerry devices are no longer subscribed. You can then deactivate those subscriptions in your database. When you remove or deactivate those subscriptions, you shorten your push cycle and then you can push more messages before reaching your push quota.
In order to understand the results of a subscription query, you need to understand how the BlackBerry Push Service responds when a BlackBerry device user no longer has your client application, either because the user removed the application without cancelling the subscription, or changed BlackBerry devices.
After you send a push message with confirmed reliability, the following events happen for each addressed BlackBerry device without your application. The BlackBerry device notifies the BlackBerry Push Service that the application is not running. The BlackBerry Push Service generates an error and removes the subscription from the list that the BlackBerry Push Service maintains. The BlackBerry Push Service no longer sends data to the device. If the BlackBerry Push Service did send the data, the device user would be charged for the data even though the BlackBerry device had discarded the data because the intended application is not there.
After the BlackBerry Push Service removes the subscription in its records, any subsequent push messages cause the BlackBerry Push Service to remove the PIN (if necessary) from the request. For content providers with the BlackBerry Push Plus package, if you send a status query for a PIN without a client application, the BlackBerry Push Service sends an error back to you.
All content providers can use a subscription query request to query the status of up to 10,000 PINs. The BlackBerry Push Service returns the status for each PIN so that you can process it accordingly. You can request a specific status (active or suspended), and the BlackBerry Push Service returns a list of PINs that have that status. You should deactivate any PINs that the BlackBerry Push Service does not record as active or suspended.