title: GCM Token validation
body: <p>I am little bit confused in validating the GCM token. I am working in cross platform application using Sencha framework and my server side is in Java. I have a query regarding how to validate the registration ID (GCM token)? Is there any specific API to validate the GCM token? Can you guide me how to handle this, either in client side or server side? I have already did registration part in server side, where user can register their GCM token in database. Now I need to validate this registration token.</p>
  
  <p>Is unregistering the application every 2 weeks a good approach ?</p>