Problems with QoS > 0

Describe your question

Hi, i recently created 2 c# application with the MqttNet nuget. All works perfectly, but I have some problems with the redelivery of the QoS 1 and 2 messages not delivered (client offline).

My client connection code is like this:

`static async void StartClient() { //private System.Diagnostics.EventLog Log;

        //IsoftMQTTClient settings = new IsoftMQTTClient();
        //settings.LoadSettings();
        //StartServer();
        EventLog Log1 = new EventLog();

        if (!EventLog.SourceExists("IsMQTTClient"))
            EventLog.CreateEventSource("IsMQTTClient", "IsMQTTClient");

        Log1.Source = "IsMQTTClient";
        Log1.Log = "IsMQTTClient";
        


        try {
            // Create a new MQTT client.
            var factory = new MqttFactory();
            var mqttClient = factory.CreateMqttClient();


            MqttClientOptions options;

            //Log1.WriteEntry("aaa " + GlobalVar.MQTT_CLIENT_CLEAN_SESSION.ToUpper());

            if (GlobalVar.MQTT_CLIENT_CLEAN_SESSION.ToUpper() == "S")
            {
                // Create TCP based options using the builder.
                options = (MqttClientOptions)new MqttClientOptionsBuilder()
                    .WithClientId(GlobalVar.MQTT_CLIENT_CLIENT_ID_WINDOWS_SERVICE)
                    .WithTcpServer(GlobalVar.MQTT_BROKER_HOST, Int32.Parse((GlobalVar.MQTT_BROKER_PORT))) // Port is optional
                    .WithCredentials(GlobalVar.MQTT_BROKER_USERNAME, GlobalVar.MQTT_BROKER_PASSWORD)
                    .WithCommunicationTimeout(new TimeSpan(0, 1, 0))
                    //.WithTls()
                    .WithCleanSession()
                    .Build();
            }
            else
            {
                options = (MqttClientOptions)new MqttClientOptionsBuilder()
                    .WithClientId(GlobalVar.MQTT_CLIENT_CLIENT_ID_WINDOWS_SERVICE)
                    .WithTcpServer(GlobalVar.MQTT_BROKER_HOST, Int32.Parse((GlobalVar.MQTT_BROKER_PORT))) // Port is optional
                    .WithCredentials(GlobalVar.MQTT_BROKER_USERNAME, GlobalVar.MQTT_BROKER_PASSWORD)
                    .WithCommunicationTimeout(new TimeSpan(0, 1, 0))
                    .WithCleanSession(false)
                    //.WithTls()
                    .Build();
            }

            //Log1.WriteEntry(options.CleanSession.ToString());

            await mqttClient.ConnectAsync(options, CancellationToken.None); // Since 3.0.5 with CancellationToken
            Log1.WriteEntry("### CONNECTED TO BROKER ###");
            //await mqttClient.SubscribeAsync(new MqttTopicFilterBuilder().WithTopic("#").Build());
            //Log1.WriteEntry("### SUBSCRIBED TO ALL TOPICS ###");
            SubscribeToTopics(GlobalVar.MQTT_CLIENT_TOPIC_SUBSCRIPTION, mqttClient, options);
            //while (true)
            //{
            await PoolMessagesAsync(mqttClient, options);
            //}


            //Console.ReadKey();
        } catch (Exception ex) { Log1.WriteEntry("Errore: " + ex.ToString()); }
        }`

inside SubscribeToTopics() i’m subscribing to all topics available, and while client is connected i recive every message the broker recives await mqttClient.SubscribeAsync(new MqttTopicFilterBuilder().WithTopic("#").Build()); Log1.WriteEntry("### SUBSCRIBED TO ALL TOPICS ###");

My Broker is hosted like this: `static async void StartServer() { var factory = new MqttFactory();

        // Configure MQTT server.
        var optionsBuilder = new MqttServerOptionsBuilder()
            .WithConnectionValidator(c =>
            {
                if (c.ClientId.Length < 1)
                {
                    c.ReasonCode = MqttConnectReasonCode.ClientIdentifierNotValid;
                    return;
                }

                System.Diagnostics.EventLog Log1;

                Log1 = new EventLog();

                if (!EventLog.SourceExists("IsMQTTBroker"))
                    EventLog.CreateEventSource("IsMQTTBroker", "IsMQTTBroker");

                Log1.Source = "IsMQTTBroker";
                Log1.Log = "IsMQTTBroker";

                //Log1.WriteEntry(GlobalVar.MQTT_BROKER_HOST);
                //Log1.WriteEntry(GlobalVar.MQTT_BROKER_PORT);
                //Log1.WriteEntry(GlobalVar.MQTT_BROKER_USERNAME);
                //Log1.WriteEntry(GlobalVar.MQTT_BROKER_PASSWORD);
                //Log1.WriteEntry(GlobalVar.MQTT_CLIENT_CLIENT_ID_WINDOWS_SERVICE);
                //
                //Log1.WriteEntry("c Username " +c.Username);
                //Log1.WriteEntry("c Password " + c.Password);
                //Log1.WriteEntry("Int32.Parse((GlobalVar.MQTT_BROKER_PORT)) " + Int32.Parse((GlobalVar.MQTT_BROKER_PORT)).ToString());


                if (c.Username != GlobalVar.MQTT_BROKER_USERNAME)
                {
                    c.ReasonCode = MqttConnectReasonCode.BadUserNameOrPassword;
                    return;
                }

                if (c.Password != GlobalVar.MQTT_BROKER_PASSWORD)
                {
                    c.ReasonCode = MqttConnectReasonCode.BadUserNameOrPassword;
                    return;
                }

                c.ReasonCode = MqttConnectReasonCode.Success;
            })
            .WithConnectionBacklog(100)
            .WithDefaultEndpointPort(Int32.Parse((GlobalVar.MQTT_BROKER_PORT)))
            .WithPersistentSessions();

        var mqttServer = new MqttFactory().CreateMqttServer();
        await mqttServer.StartAsync(optionsBuilder.Build());

        Console.WriteLine("Press any key to exit.");
        Console.ReadLine();
        //await mqttServer.StopAsync();
    }`

when i stop my client, send some messages with QoS 1 or 2 and start my client again those messages are vanished. I have a static and unique ClientID, and the client is always started with “.WithCleanSession(false)”. Any idea on what i’m missing to manage those messages recived while offline?

Thanks

Best regards, Andrea

Which project is your question related to?

• Client
• Server

[davemcdermid]

Sorry I can’t help further, I’m really not an expert here. I found http://mqtt-explorer.com/ useful for visualising what was happening, and Wireshark for digging into what was really being sent & received. Not sure if that’s helpful for you.

[dkavicki]

fwiw I had the same issue until I did .WithSessionExpiryInterval(9999) Then it worked for me. (with the ManagedClient) However, I’ve noticed that my test Mqttnet server would send the message every time (and not just once) whenever I start and connect the client again