anchor.diff:          var kioskIds = data[0];
           var signId = data[1];
           if (kioskIds.isEmpty) {
  -          for (var kioskID = 1; kioskID < nextKioskId; kioskID++) {
  -            signIdsForKioskIds[kioskID] = signId;
  +          for (var kioskId = 1; kioskId < nextKioskId; kioskId++) {
  +            signIdsForKioskIds[kioskId] = signId;
  +            notify(subscribers[kioskId], signId);
             }
           } else {
             for (var kioskId in kioskIds) {
               signIdsForKioskIds[kioskId] = signId;
  +            notify(subscribers[kioskId], signId);
             }
           }
  -        print('$signIdsForKioskIds');
           // reply with the Empty() message
           replyTo.send(Empty());
           break;
         case Command.get_sign_id_for_kiosk_id:
           var reply = GetSignIdResponse();
  -		var signId = signIdsForKioskIds[data.kioskId];
  +        var signId = signIdsForKioskIds[data.kioskId];
           if (signId != null) {
  -			reply.signId = signId;		
  -		}
  +          reply.signId = signId;
  +        }
           replyTo.send(reply);
           break;
         case Command.get_sign_ids_for_kiosk_id:
  +        if (subscribers[data.kioskId] == null) {
  +          subscribers[data.kioskId] = List<SendPort>();
  +        }
  +        subscribers[data.kioskId].add(replyTo);
  +        var reply = GetSignIdResponse();
  +        var signId = signIdsForKioskIds[data.kioskId];
  +        if (signId != null) {
  +          reply.signId = signId;
  +        }
  +        replyTo.send(reply);
           break;
         default:
           replyTo.send(data);
  
positive.code:   var signIdsForKioskIds = <int, int>{};
    var nextKioskId = 1;
    var nextSignId = 1;
  
    // create receive port and send it to the listener
    var port = new ReceivePort();
  
negative.code:     dataManagerSendPort
          .send([Command.get_sign_ids_for_kiosk_id, request, response.sendPort]);
      await for (var value in response) {
        yield value;
      }
  	print('lost connection');
    }
  }
  
  