Services & Broadcast receivers

We're only going to look at a small subset of this topic: Intent Services.

We'll create an Intent Service as described here. The service overview has a little too much information.
Then our activity (which has to be in the same project as the service) will call one function of the service with a parameter or two.
Once the service is done its work - it will send a response back via an Broadcast Intent
- Which means we'll need to register to receive those in our activity. We'll create an IntentFilter and a BroadcastReceiver in Java and register them with LocalBroadcastManager.getInstance(this).registerReceiver().
- And since our activity may not be running at this point - we'll use a Notification to show that we got the message.

Reading incoming SMS

We can send a fake SMS to an emulator using telnet and receive it using a BroadcastReceiver. Follow this tutorial.