CODEWITHSUNDEEP
android
WorkerThread
WorkerThread

Reputation: 2213

Android long-duration socket listener

My company has, in essence, undertaken a project to replace some of its pagers with stock smartphones running Android. As long as they are signed in, the device should be listening on a particular socket to receive "pages" from a server. My naive implementation was to create a foreground service that 1) kicked off a listening thread, and 2) holds a PARTIAL_WAKE_LOCK.

This works fine unless the device has a long period of inactivity, 1+ hours. Then, it appears that the OS shuts down my app's process, understandably believing it to be not in use.

I completely understand their reasons for doing so, but I'm wondering if I can somehow get around this restriction. Are there ways to signal Android that my process really is important enough to keep alive/the device awake? I learned both Java and the Android API for this project, so there are plenty of areas where my knowledge is incomplete.

Failing that, given the description of my business needs, how would you suggest implementing this functionality? While the user is signed in to our custom app, the device should always be listening.

Thanks to everyone for reading this question.

Upvotes: 1

Views: 1318

Answers (2)

Squonk
Squonk

Reputation: 48871

What you describe sounds like a job for Android Cloud to Device Messaging Framework.

It's currently not completely open but there is a signup link on that page. I signed up and was accepted within 20 minutes of my application. Worth a look IMO.

Upvotes: 0

hackbod
hackbod

Reputation: 91331

The OS won't kill your process if you are using Service.startForground(). This is what things like music playback use, and you wouldn't want those to be killed after some amount of time.

That said, for this kind of thing you generally wouldn't need to make your service foreground -- when the system does kill your process because it has been sitting around or needs the memory, it still knows the service wants to remaining running so will restart the service shortly after that. This is how Google's own services work, they have one .apk that has a background service running that keeps a network connection open to a Google service which reports back when interesting things should be done like sync new e-mail, retrieve and deliver a C2DM Intent, etc.

Also you should not hold a wake lock during all of that time. You will kill the battery, especially on some devices like those with Samsung's Hummingbird processor. The right way to do this is to just leave the socket open and let the device fall asleep. If data is delivered to the socket, the CPU will wake up to deliver that data and at that point you should acquire a partial wake lock just for the time you need to read and process the data.

Upvotes: 4

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