Hello,

thanks for your elaboration. However your solution seems not to work for me at all. I guess my explanation was a bit clumsy.

The client needs to:

• recover from a server-down
• recover from short connection losses to the server (seconds to minute)
• recover from long connection losses (minutes to days)

I have tried various things to get notified:

• DEFAULT_ERROR_SUBJECT
• TransportErrorHandler
• LogAdapter
• SessionExpirationListener

My observations are:

Case A: Server terminated.

1. TransportErrorHandler gets called, prints out error code 12152
2. CLIENT_ERROR_SUBJECT gets called
3. LogAdapter gets called

Case B: Link is down for a long time, no self implemented heartbeat system

1. Unsubscription events are fired on the server after some time
2. Client sees nothing at all

Case C: Link is down for a long time, self implemented heartbeat system (see bottom of this post for explanation)

1. Unsubscription events are fired on the server after some time
2. SessionExpiration on clients
3. LogAdapter is called

     When the links is back, on the server there are several messages:

08:30:15,589 ERROR [org.jboss.stdio.AbstractLoggingWriter] *** Message delivery failure ***
08:30:15,589 ERROR [org.jboss.stdio.AbstractLoggingWriter] Bus: org.jboss.errai.bus.server.ServerMessageBusImpl@6f14d6
08:30:15,589 ERROR [org.jboss.stdio.AbstractLoggingWriter] Message: ReplyTo=MonitoringService:RespondTo:47, ToSubject=MonitoringService
08:30:15,589 ERROR [org.jboss.stdio.AbstractLoggingWriter] errorMessage: Error calling remote service: MonitoringService
08:30:15,589 ERROR [org.jboss.stdio.AbstractLoggingWriter] exception: org.jboss.errai.bus.client.api.base.MessageDeliveryFailure: unable to deliver message: no queue available to send. (queue or session may have expired): (session id: bd142e35e85e1e0cee3ec8c09b5ddea1de4b3a385ab489935e312f7b7db9)
08:30:15,589 ERROR [org.jboss.stdio.AbstractLoggingWriter] disconnect: false
08:30:15,605 ERROR [org.jboss.stdio.AbstractLoggingWriter] org.jboss.errai.bus.server.QueueUnavailableException: no queue available to send. (queue or session may have expired): (session id: 2177edff95b06ca690ce64c4e5aa5f6db315dc9a7d349ecc9993bd7c334)

Case D: Links is down for a short time, self implemented heartbeat system

1. Heartbeats are restored, sessions are kept, everything is fine.

Heartbeats:

From my understanding, the bus has a heartbeat system that keeps the connection alive. These heartbeats are exchanged in the background as described here:

     http://docs.jboss.org/errai/2.1.0.Final/errai/reference/html/sid-5931263.html#sid-5931315_QueueSessions-Lifecycle

But this comment makes me unsecure:

     https://issues.jboss.org/browse/ERRAI-66

How is the heartbeat system working?

My self implemented heartbeat:

On Client:

Timer timer = new Timer() {
            
            @Override
            public void run() {
                logger.info("Heartbeat");
                MessageBuilder.createMessage()
                    .toSubject("MonitoringService")
                    .with(MessageParts.ReplyTo, "ClientEndpoint")
                    .defaultErrorHandling()
                    .repliesTo(new MessageCallback() {
                        
                        @Override
                        public void callback(Message message) {
                            logger.info("Heartbeat callback");
                        }
                    })
                    .sendNowWith(bus);
            }
        };
        timer.scheduleRepeating(5000);

On server:

@Service
public class MonitoringService implements MessageCallback {
    private static final Logger logger = Logger.getLogger(MonitoringService.class);
    
    @Override
    public void callback(Message message) {
        // TODO Auto-generated method stub
        logger.info("Monitoring service...");
        MessageBuilder.createConversation(message)
            .subjectProvided()
            .signalling()
            .defaultErrorHandling()
            .reply();
    }
}

On client log output: (No transport error)

Conclusion:

I guess i could use the self implemented heartbeat system to fulfill my requirements, i however thought that something similar was available inside Errai.

I don't quite understand why I only get SessionExpiration when I constantly talk to the server.

Additionally, the Heartbeat I described above should throw some error, doesn't it? I mean, the message does not get through. Is there a timeout available?

Regards,

Sven