Gostaria de receber notificações por push quando meu aplicativo estiver aberto, mas estiver em segundo plano. Por enquanto, alterei a demonstração do Estimote e meu aplicativo me envia uma notificação quando meu aplicativo está em primeiro plano, o que não é muito útil. Coloco aqui meu código da classe NotifyDemoActivity, que é chamado assim que abro o aplicativo

public class NotifyDemoActivity extends Activity {
  private static final String TAG = NotifyDemoActivity.class.getSimpleName();
  private static final int NOTIFICATION_ID = 123;
  private BeaconManager beaconManager;
  private NotificationManager notificationManager;
  private Region region;
  private long[] mVibratePattern = { 0, 200, 200, 300 };

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.notify_demo);
    getActionBar().setDisplayHomeAsUpEnabled(true);

    beacon.getMinor());
    region = new Region("rid", null, null, null);
    notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    beaconManager = new BeaconManager(this);

    beaconManager.setBackgroundScanPeriod(TimeUnit.SECONDS.toMillis(1), 0);

    beaconManager.setMonitoringListener(new MonitoringListener() {
      @Override
      public void onEnteredRegion(Region region, List<Beacon> beacons) {
        postNotification("Entered region");
      }

      @Override
      public void onExitedRegion(Region region) {
        postNotification("Exited region");
      }
    });
  }

  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getItemId() == android.R.id.home) {
      finish();
      return true;
    }
    return super.onOptionsItemSelected(item);
  }

  @Override
  protected void onResume() {
    super.onResume();
    notificationManager.cancel(NOTIFICATION_ID);
    beaconManager.connect(new BeaconManager.ServiceReadyCallback() {
      @Override
      public void onServiceReady() {
        try {
          beaconManager.startMonitoring(region);
        } catch (RemoteException e) {
          Log.d(TAG, "Error while starting monitoring");
        }
      }
    });
  }

  @Override
  protected void onDestroy() {
    notificationManager.cancel(NOTIFICATION_ID);
    beaconManager.disconnect();
    super.onDestroy();
  }

  private void postNotification(String msg) {
    Intent notifyIntent = new Intent(NotifyDemoActivity.this, NotifyDemoActivity.class);
    notifyIntent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
    PendingIntent pendingIntent = PendingIntent.getActivities(
      NotifyDemoActivity.this,
      0,
      new Intent[]{notifyIntent},
      PendingIntent.FLAG_UPDATE_CURRENT);
    Notification notification = new Notification.Builder(NotifyDemoActivity.this)
    .setSmallIcon(R.drawable.beacon_gray)
    .setContentTitle("Notify Demo")
    .setContentText(msg)
    .setAutoCancel(true)
    .setContentIntent(pendingIntent)
    .setVibrate(mVibratePattern)
    .build();
    notification.defaults |= Notification.DEFAULT_SOUND;
    notification.defaults |= Notification.DEFAULT_LIGHTS;
    notificationManager.notify(NOTIFICATION_ID, notification);

    TextView statusTextView = (TextView) findViewById(R.id.status);
    statusTextView.setText(msg);
  }
}