Last Will Not Working

[Rob-Hamilton]

Describe your question

I am unable to get the Last Will and Testament working. Any help or guidance would be greatly appreciated.

Which project is your question related to?

• Client

For my test I am using:

• Mosquito Broker Port 1883.
• MQTT Explorer to watch the topic messages.
• Visual Studio C# with Frameworks v4.8
• MQTTnet.4.3.7.1207

I modified this example

• I placed the example code in a Windows Form in a button click event.
• I commented out the unsubscribe & disconnect code.
• Ran the test project and used Task Manager to Kill it.
• MQTT Explorer does not seem to get the LWT.

CODE:

using MQTTnet;
using MQTTnet.Client;
using MQTTnet.Formatter;
using MQTTnet.Protocol;
using System;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp6
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private async void Button1_Click(object sender, EventArgs e)
        {
            var broker = "LocalHost";
            var port = 1883;
            var clientId = Guid.NewGuid().ToString();
            var topic = "csharp/mqtt";

            // Create a MQTT client factory
            var factory = new MqttFactory();

            // Create a MQTT client instance
            IMqttClient mqttClient = factory.CreateMqttClient();

            // Create MQTT client options
            MqttClientOptions options = new MqttClientOptionsBuilder()
                .WithTcpServer(broker, port) // MQTT broker address and port
                .WithClientId(clientId)
                .WithCleanSession()

                .WithKeepAlivePeriod(new TimeSpan(0, 0, 30))
                .WithProtocolVersion(MqttProtocolVersion.V500)
                .WithCleanSession(true)

                .WithWillPayload("My Last Will")
                .WithWillQualityOfServiceLevel(MQTTnet.Protocol.MqttQualityOfServiceLevel.AtLeastOnce)
                .WithWillResponseTopic("csharp/LW")
                .WithWillRetain(true)

                .Build();

            // Connect to MQTT broker
            MqttClientConnectResult connectResult = await mqttClient.ConnectAsync(options);

            if (connectResult.ResultCode == MqttClientConnectResultCode.Success)
            {
                Console.WriteLine("Connected to MQTT broker successfully.");

                // Subscribe to a topic
                await mqttClient.SubscribeAsync(topic);

                // Callback function when a message is received
                mqttClient.ApplicationMessageReceivedAsync += ee =>
                {
                    //Console.WriteLine($"Received message: {Encoding.UTF8.GetString(ee.ApplicationMessage.PayloadSegment)}");
                    return Task.CompletedTask;
                };

                // Publish a message 10 times
                for (var i = 0; i < 100; i++)
                {
                    MqttApplicationMessage message = new MqttApplicationMessageBuilder()
                        .WithTopic(topic)
                        .WithPayload($"Hello, MQTT! Message number {i}")
                        .WithQualityOfServiceLevel(MqttQualityOfServiceLevel.AtLeastOnce)
                        .WithRetainFlag()
                        .Build();

                    await mqttClient.PublishAsync(message);
                    await Task.Delay(1000); // Wait for 1 second
                }

                //// Unsubscribe and disconnect
                //await mqttClient.UnsubscribeAsync(topic);
                //await mqttClient.DisconnectAsync();
            }
            else
            {
                Console.WriteLine($"Failed to connect to MQTT broker: {connectResult.ResultCode}");
            }

        }

    }
}