Set an expiration date for Win8 periodic tile notifications and renew the notification channel

Question

I am (still) working on a WIn8-UI-App (previously called Metro...) and I implemented Periodic Tile Updates. (Also with your help, see this post.)

I have two follow-up questions:

1. How can I set an expiration date for periodic tiles? As written in the documentation I have to provide a X-WNS-Expires header of the notification's HTTP response message. The message is the XML-(tile)-file. How can I add the expiration date (example)?

2. While I was reading a couple tutorials and the documentation, I read that the notification service (the abonnement which renews the tiles) never expires. In a sample code (by MS) I read that it expires after 30 days and I should renew it whenever the app is launched and that I should consider using a background task. What is right now and what should I do for my app that might get only used once every two months (but the notification tiles have to be on the whole time)?

Thank you for your help!

Answer 1

The endpoint that you specify for the periodic notification needs to serve the XML content and set the X-WNS-Expires header (and perhaps X-WNS-Tag). If, for example, you're using Windows Azure blob storage or Amazon S3 to host the template XML and sending that URI to startPeriodicUpdate, then you don't have the opportunity to set those headers. You'll need to set up a lightweight service that passes through the XML content and sets the headers appropriately.

The 30-days refers to a push notification channel, not the periodic notification registration, which is just a URI that's polled on whatever interval you specify. That URI will be checked until you call stopPeriodicUpdate; see Periodic Notification Overview:

Polling continues until you explicitly stop it or your app is uninstalled. Otherwise, Windows will continue to poll for updates to your tile or badge even if your app is never launched again.

Lastly, the Guidelines and checklist for periodic notifications does recommend:

Call the StartPeriodicUpdate or StartPeriodicUpdateBatch method each time your app is launched or brought into focus. This ensures that the tile content will be updated each time the user launches or switches to the app.