title: Keep notification service in background like stackoverflow app
body: <p>I have a service, which monitors a server for changes.</p>
  
  <p>When I open the app and just press my home button to leave it, all works fine.</p>
  
  <p>But when I kill the app from the "recent apps" view, I don't get any notifications anymore.</p>
  
  <p>I know that there is way, to use <a href="https://developer.android.com/reference/android/app/Service.html#startForeground(int,%20android.app.Notification)" rel="nofollow">startForeground</a>. But then I have to display a notification.</p>
  
  <p>But how does the stackoverflow app work? There is no notification, no entry in the android account manager or anywhere else. But without starting it and without keeping it in the recent view, I get notifications for new answers. </p>
  
  <p>How does it work?</p>