Background File Transfer problems

Question

I have this problem when using the Background File Transfer in WP7. It works perfectly when my application is running, but as soon as I click the Windows button, it stops(and resumes when I activate the application again.) Isn´t the purpose of Background File Transfer to run in the background, even when your application is deactivated? Does it have to be in a separate class(some sort of background agent class, separate from the main project?) Really frustrating, when I am doing all that the tutorial here says: http://msdn.microsoft.com/en-us/library/hh202959(v=vs.92).aspx.

Are there some "special" things I need to do to make sure it runs in the background, or some methods, maybe the ones I created by myself(to get the url etc.), that can not be accessed while deactivated? Can I not add to the queue while deactivated, maybe?

Thanks a lot for your time:)

EDIT: A little debugging tells me that the file in the queue is actually downloading. It gets finished, but it doesn´t fetch the next one until I reactivate the app. Can I not use my own methods, variables etc when doing this? Maybe I have an internal queue for, say, 20 items. How can I then populate the download queue(max 5) when this gets to zero?

EDIT2: In the sample from Microsoft, they say that you can add to the queue at a later time:

// Check to see if the maximum number of requests per app has been exceeded.
if (BackgroundTransferService.Requests.Count() >= 5)
{
// Note: Instead of showing a message to the user, you could store the
// requested file URI in isolated storage and add it to the queue later.
MessageBox.Show("The maximum number of background file transfer requests for this application has been exceeded. ");
return;
}

But it does not say if we can do this while in background or not. Since it is about background file transferring, they should have mentioned it, otherwise we should assume it can be done in the background, which seems not to be the case. But we can´t know that. Anyone who can confirm this 100%?

Answer 1

I have looked into this as well and it isn't possible (based on my research) to populate the queue after the max. 5 queued downloads have finished. I thought about using a background agent but BackgroundTransferRequest.Add is unavailable from background agents meaning the only way to queue more downloads is when your app is running (see Unsupported APIs for Background Agents for Windows Phone).

The only thing I can think of is using a background agent to send a toast notification letting the user know that the downloads have finished and that they should start the app to queue the next five downloads. This is less than ideal.