Sessions does not persist for build in Publish method

[drmagice]

Sessions does not persist for build in Publish method

[DrmagicE]

This should not happen. To preserve the session or not depends on the CleanSession setting of the client. Make sure the reconnected client has the same clientID as before, and also keep CleanSession setting to be false.

I run the following code with the latest version(master branch):

func main() {
	s := gmqtt.DefaultServer()
	// listener
	ln, err := net.Listen("tcp", ":1883")
	if err != nil {
		log.Fatalln(err.Error())
		return
	}
	s.AddTCPListenner(ln)
	ws := &gmqtt.WsServer{
		Server: &http.Server{Addr: ":8080"},
	}
	s.AddWebSocketServer(ws)

	// plugin
	s.AddPlugins(management.New(":9090", nil))

	log.Println("started...")
	s.Run()
	signalCh := make(chan os.Signal, 1)

	go func() {
		for {
			<-time.After(2 * time.Second)
			s.Publish("topic1", []byte("payload"), 0, false)
		}
	}()

	signal.Notify(signalCh, os.Interrupt, syscall.SIGTERM)
	<-signalCh
	s.Stop(context.Background())
	log.Println("stopped")

}

and use the following MQTT client tool to test your problem.
https://www.eclipse.org/paho/components/tool/

In my test case, the client will receive the message when it reconnects.

[DrmagicE]

By the way, there is no client in gmqtt server. The Publish method is not a client, it just sends the Publish Packet into a channel and then checks whether there is any matched subscription and delivery the message to matched clients. If any matched client is disconnected and the CleanSession setting is false(which means that the session will be preserved by gmqtt), the message will be delivered when the client reconnect with the same clientID and CleanSession = false setting .

[sh0umik]

Solved this problem with Client Side CleanSession set to false. When the clients connects and if the sessions is preserved then I got the message. Thx.

I have few more questions..

Is there anyway to persists all the client sessions ? How do I approach to ReSchedule Message Queue if I restart the gmqtt server ?

I am thinking about an use case in notifications.

What should be the best approach for that ? Can you guide or share a little bit documentation on implementing my own sessions.go with any key value store like redis instead of container/list package ?

[DrmagicE]

According to MQTT protocol, the CleanSession flag is on the client side, so the only way to preserve all sessions is to set the CleanSession flag for all clients.

But you can call Subscribe method in onConnected hook method to resume the subscription for the client. Notice that resuming subscription is not the same as resuming a session, because in MQTT protocol, the session is more than subscriptions.

What do you mean ReSchedule Message Queue when restart the gmqtt server?

Gmqtt does not support k/v store for session, it needs a FIFO queue to get better performance.

[DrmagicE]

Also i am using a plugin approach to re schedule the message from db with the publish method if the gmqtt server gets restarts. I am using the build in publish method for that.

If you want to publish message when a client connected, using Publish method in onConnected hook should work.

[DrmagicE]

Closed. Feel free to reopen it if you have any further questions.

[sh0umik]

No further questions. I have figured out a way to solve my problem using hooks. Thx for the suggestions.