Android : Stopping a Bonjour service left running after the parent process quit abrubtly

Issue

My app is essentially a background service that needs to occasionally register an NSD service (Bonjour service) for the purpose of enabling discovery of a socket server run by the main background service (aka run by the app).

If I am reading the Android Bonjour Service doc correctly, this is how you start the Bonjour service (abbreviated for conciseness):

mNsdManager = Context.getSystemService(Context.NSD_SERVICE);
mDiscoveryListener = new NsdManager.DiscoveryListener()
mNsdManager.discoverServices(
        SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, mDiscoveryListener);

...and this is how you stop it:

mNsdManager.unregisterService(mRegistrationListener);

Here the part I can't wrap my head around: if the main service goes down abruptly, any Bonjour service that was registered at the time of the crash keeps running even though it no longer has a purpose (the socket server it helps discover is no longer around).

I can't event cleanup the zombie Bonjour services when the main service is restarted because the mRegistrationListener the service was initially registered with is also no longer around.

I suspect I am taking the wrong approach: how do I make sure I don't leave a mess of zombie Bonjour services behind after the main service crashed?

Solution

Non-specific to Android Bonjour, you could try to handle the crash by setting up your service as is outlined in the answer here: Can I call a method before my application go to crash

If you can't set this up to make the unregisterService call, you should be able to set it up to use ActivityManager's API killBackgroundProcesses. This requires adding the permission to your manifest:

android.permission.KILL_BACKGROUND_PROCESSES

Answered By - Steve Seeger