title: Invite and share app data between android devices
body: <p>I´m trying to develop my first Android app. It´s basically a score counter. My idea is to add a functionality like other apps like Wunderlist:</p>
  
  <p>1) User A and user B have the app installed in their devices.</p>
  
  <p>2) User A create a game score with two players (stored in xml format).</p>
  
  <p>3) User A sends an invitation to user B to share this game score (maybe using its google account).</p>
  
  <p>4) User B receives the invitation/notification and accept it.</p>
  
  <p>5) Both users share the score, they can change it, and the score is updated in both devices every time it´s changed, so that both users have the same score.</p>
  
  <p>6) If the score is deleted, the app send a notification to delete it in the other device.</p>
  
  <p>In Wunderlist app, for example, you can create a list and invite someone to share the list. There is a lot of Android apps, like production apps, that share information this way.</p>
  
  <p>¿How can I implement this?</p>
  
  <p>Thanks in advance.</p>