MQTTStudy/MQTTSample/MqttPublisherApp/Program.cs

using MQTTnet.Server;
using MQTTnet;
using MQTTnet.Client;
using System.Text;

namespace MqttPublisherApp
{
    internal class Program
    {
        private static string CLIENT_ID = "PublisherClient";
        private static string SERVER_IP = "localhost";
        private static readonly int PORT = 1883;
        private static readonly string TOPIC = "home/kitchen/temperature";

        static async Task Main(string[] args)
        {
            var mqttFactory = new MqttFactory();
            var mqttClient = mqttFactory.CreateMqttClient();

            var options = new MqttClientOptionsBuilder()
                .WithClientId(CLIENT_ID)
                .WithTcpServer(SERVER_IP, PORT)
                .Build();

            await mqttClient.ConnectAsync(options);
            while (true)
            {
                Console.WriteLine("Enter a message to publish: ");
                var message = Console.ReadLine();

                var mqttMessage = new MqttApplicationMessageBuilder()
                    .WithTopic(TOPIC)
                    .WithPayload(Encoding.UTF8.GetBytes(message))
                    .WithQualityOfServiceLevel(MQTTnet.Protocol.MqttQualityOfServiceLevel.AtLeastOnce)
                    .Build();

                await mqttClient.PublishAsync(mqttMessage);
                Console.WriteLine($"Message '{message}' published.");
            }
        }
    }
}