title: How to implement a informming messages in application like kivy?
body: <p>In facebook and some messaging apps, when we have messages from somebody we get the message "received message".</p>
  
  <p>This tells us every time when we have received message.</p>
  
  <p>(I'll develop this app in android with kivy)</p>
  
  <p>Question is=</p>
  
  <ol>
  <li><p>How can a application notice when received a message? Is the process is running even its closed? or is it still running while its window is closed</p></li>
  <li><p>What kind of Kivy API will help to implement it?</p></li>
  </ol>