is it possible to make an alarm or countdown timer app?

I'm a complete noob when it comes to WP7. From what I know of it, in WP7 you wouldn't be able to make an alarm clock app. As in, start app, set alarm for an hour from now, close app, app launches and rings alarm after an hour is up.

Is this not possible in WP7? Or is there some way of doing it that I'm not aware of? I have seen a workaround for a stopwatch using tombstoning, but that doesn't seem like it would work here开发者_运维百科.

With Windows Phone 7 [for 3rd party developers] it's not possible to write an application that runs in the background on the phone. (This was a deliberate decision with regards to maintaining performance and battery life - not a limitation of the OS which is fully multi-tasking.)

If you really want the user to be notified of something at a specific time, regardless of whether your application is running you'll need to have this monitored from a process on an external server and then send a [toast] notification to the user at the appropriate time.

Learn more about push notifications at http://msdn.microsoft.com/en-us/library/ff402537(VS.92).aspx