Android BroadcastReceiver

http://www.techrepublic.com/blog/app-builder/an-android-coders-introduction-to-broadcast-receivers/1173
http://www.9android.net/broadcast-receiver/
http://www.grokkingandroid.com/android-tutorial-broadcastreceiver/
http://www.edureka.in/blog/android-tutorials-broadcast-receivers/