Best way to create a service that doesn't die.(like WhatsApp or Facebook)

Question

I have tried till now - start sticky - alarm to restart service - on task removed start the service - use job service (has latency and executes task slow)

Is there a proper method to make an infallible background service like the popular apps?

Answer 1

Creating a background service that "does not die" is not possible in android.

You can create a service and take certain measures to have it running as much as possible, but the OS will kill it at times and your service will not be running until the OS decides to restart it (in case it is a sticky service).

Things you can do:

• Make the service sticky, so that it will be restarted by the OS after the OS kills it. It is impossible to predict when it will be restarted. It can be almost instant, it can take seconds, minutes, hours, or more.
• Start the service when you open the app.
• Start the service when the app is upgraded, using the MY_PACKAGE_REPLACED broadcast.
• Start the service when the device is (re)booted, using the BOOT_COMPLETED and REBOOT broadcasts.
• Override onTaskRemoved in the service, to schedule a restart of the service in case the user swipes away your app from the list of recent apps.
• Use FCM to periodically send messages to the app with an instruction to start the service in case it is not running anymore.

You can never have a 100% uptime, but this will get you close.

Answer 2

A background service, if not visible by the user will always be killed earlier or later by the Android system. It is the way memory management work.

If you really need to make a service continously run, you need to show a permanent notification to the user (like when you are using a radio app or a music player app).

What whatsapp and facebook probably do is to wake up the app remotely with any sort of messaging such as Firebase Cloud Messaging (ex-Google Cloud Messaging) or using Broadcast Receiver on certains events... But it surely isn't en ever going on service.

Read this part of Android documentation to better understand this: Service Process Lifecycle.

As you can see, to give priority to your service process you will need to start it in foreground and pass it an Ongoing Notification using startForeground(int id, Notification notification). Use setOngoing(true) in your NotificationBuilder to set a Notification as an Ongoing one: setOngoing(boolean b) doc.

Finally you usually want to add action in your Ongoing Notification (such as Player controls or the possibility to close the notification and hence your service when memory will be collected)

Here a full sample code:

    Notification notification = new NotificationCompat.Builder(this)
        .setContentTitle(getString(R.string.notification_title))
        .setContentText(getString(R.string.notification_text))
        .setSmallIcon(R.drawable.ic_small_icon)
        .setColor(getResources().getColor(R.color.colorAccent))
        .setContentIntent(pendingIntent)
        .setOngoing(true)
        //.addAction(android.R.drawable.close_service,"Close", closeServiceIntent)
        .build();
    startForeground(Constants.NOTIFICATION_ID, notification);