Android background Services, Alarms and preserving object reference after application restart

Question

I'm developing a little Android app, that needs to run a background process, used to start a remote connection periodically (for example, to check if there is new data on the server). This process obviously needs to work also if the application activity is not running at the moment.

As I can see in documentation, there are two types of approach to develop a scheduled background process in Android, working also when the application is closed.

• Services
• Alarms

The first one is not so good for my requirementes, because it can be killed by OS in case of low memory, so it is useless for me. startForeground() is not so good because I want the process is silent.

Alarm is ok, because it can't be killed by the OS, so it can work indefinitely. But... If I schedule an Intent with the AlarmManager, how can I preserve a reference to the Intent, surviving at application restart?

For example, if I want to cancel, or reschedule the Alarm, I need the reference to the initial Intent to cancel it thorugh the "AlarmManager.cancel(Intent i)" method. But if the application was restarted by the user, how can I obtain a reference to the initial Intent that was used to start the alarm?

Is there another way to stop an alarm if the launching application was restarted?

Answer 1

about alarms, you can cancel using the intent characteristics, so you don't need a reference to the original intent. In any case, the alarms mechanism still need you to run something on a service.

In any case, you missed another possible solution: SyncAdapter. Its purpose is to sync with servers, but you can do whatever you wish in the code, and it's unlikely the OS will kill it, as opposed to the other solutions you've mentioned.

Sadly even now it lacks on documentation and samples, but I think it can fulfill your needs. Here's what I've found

Answer 2

yes, note that cancel is looking for a PendingIntent, not an Intent per se.

so

PendingIntent pendingIntent = PendingIntent.getBroadcast(this, R.string.some_string, new Intent(this, InitialIntent.class), 0);
AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
alarmManager.cancel(pendingIntent);

gets you where you want to be.

note that I'm not getString'ing that string, that's becasue I want a unique Id/request code for this intent that I'm not going to screw up copypasting; I reference the same number when creating the alarm in InititalIntent.

Answer 3

This question was just answered, here:

How can I get the context of other activity?

Just cancel the intent you scheduled

Answer 4

Your best bet would be to make use to push notification (via GCM), whenever something new is available on the server. I am working on similar application where data can be pushed from one side (producers) and needs to be pushed to the consumer apps.

You need to look at BroadcastReceiver and GCM specific communication model. Hope this helps