/**
  * Register this account/device pair within the server.
  *
  * @return whether the registration succeeded or not.
  */
 static boolean register(final Context context, final String regId) {
   Log.i(TAG, "registering device (regId = " + regId + ")");
   String serverUrl = SERVER_URL + "/register";
   Map<String, String> params = new HashMap<String, String>();
   params.put("regId", regId);
   long backoff = BACKOFF_MILLI_SECONDS + random.nextInt(1000);
   // Once GCM returns a registration id, we need to register it in the
   // demo server. As the server might be down, we will retry it a couple
   // times.
   for (int i = 1; i <= MAX_ATTEMPTS; i++) {
     Log.d(TAG, "Attempt #" + i + " to register");
     try {
       // displayMessage(context, context.getString(
       //       R.string.server_registering, i, MAX_ATTEMPTS));
       post(serverUrl, params);
       GCMRegistrar.setRegisteredOnServer(context, true);
       String message = "null"; // context.getString(R.string.server_registered);
       CommonUtilities.displayMessage(context, message);
       return true;
     } catch (IOException e) {
       // Here we are simplifying and retrying on any error; in a real
       // application, it should retry only on unrecoverable errors
       // (like HTTP error code 503).
       Log.e(TAG, "Failed to register on attempt " + i, e);
       if (i == MAX_ATTEMPTS) {
         break;
       }
       try {
         Log.d(TAG, "Sleeping for " + backoff + " ms before retry");
         Thread.sleep(backoff);
       } catch (InterruptedException e1) {
         // Activity finished before we complete - exit.
         Log.d(TAG, "Thread interrupted: abort remaining retries!");
         Thread.currentThread().interrupt();
         return false;
       }
       // increase back off exponentially
       backoff *= 2;
     }
   }
   String message = "null"; // context.getString(R.string.server_register_error, MAX_ATTEMPTS);
   CommonUtilities.displayMessage(context, message);
   return false;
 }
 /** Unregister this account/device pair within the server. */
 static void unregister(final Context context, final String regId) {
   Log.i(TAG, "unregistering device (regId = " + regId + ")");
   String serverUrl = SERVER_URL + "/unregister";
   Map<String, String> params = new HashMap<String, String>();
   params.put("regId", regId);
   try {
     post(serverUrl, params);
     GCMRegistrar.setRegisteredOnServer(context, false);
     String message = "null"; // context.getString(R.string.server_unregistered);
     CommonUtilities.displayMessage(context, message);
   } catch (IOException e) {
     // At this point the device is unregistered from GCM, but still
     // registered in the server.
     // We could try to unregister again, but it is not necessary:
     // if the server tries to send a message to the device, it will get
     // a "NotRegistered" error message and should unregister the device.
     String message =
         "null"; // context.getString(R.string.server_unregister_error, e.getMessage());
     CommonUtilities.displayMessage(context, message);
   }
 }