code: private int subscribeEventWithNotifd(DeviceProxy device,
                                     String attribute,
                                     int event,
                                     CallBack callback,
                                     int max_size,
                                     String[] filters,
                                     boolean stateless) throws DevFailed {
  
          int id;
          id = NotifdEventConsumer.getInstance().subscribe_event(device,
                  attribute, event, callback, max_size, filters, stateless);
          ApiUtil.printTrace(device.name() + "/" + attribute + "  connected to Notifd event system");
          return id;
      }
docs: ===============================================================