Maybe I don't understand yet some of the Android concepts, but answering the following questions may help me a lot:

In my Android app, I need to get data from a web service each x seconds in background (application must seem to not be running).

* May I use Android Services? <http://developer.android.com/reference/android/app/Service.html>

When the data from the web service is the one I am expecting, I do need to show an Android Notification.

* How can then load my Application in a concrete activity?
* How can I ensure the background "service" will keep running even if it crashes? This is, how do I restart that background part or "service" of my application?