MQTTnet/Samples/ManagedClient/Managed_Client_Simple_Samples.cs

using MQTTnet.Client;
using MQTTnet.Extensions.ManagedClient;

namespace MQTTnet.Samples.ManagedClient;

public sealed class Managed_Client_Simple_Samples
{
    public static async Task Connect_Client()
    {
        /*
         * This sample creates a simple managed MQTT client and connects to a public broker.
         *
         * The managed client extends the existing _MqttClient_. It adds the following features.
         * - Reconnecting when connection is lost.
         * - Storing pending messages in an internal queue so that an enqueue is possible while the client remains not connected.
         */
        
        var mqttFactory = new MqttFactory();

        using (var managedMqttClient = mqttFactory.CreateManagedMqttClient())
        {
            var mqttClientOptions = new MqttClientOptionsBuilder()
                .WithTcpServer("broker.hivemq.com")
                .Build();

            var managedMqttClientOptions = new ManagedMqttClientOptionsBuilder()
                .WithClientOptions(mqttClientOptions)
                .Build();

            await managedMqttClient.StartAsync(managedMqttClientOptions);

            // The application message is not sent. It is stored in an internal queue and
            // will be sent when the client is connected.
            await managedMqttClient.EnqueueAsync("Topic", "Payload");

            Console.WriteLine("The managed MQTT client is connected.");
            
            // Wait until the queue is fully processed.
            SpinWait.SpinUntil(() => managedMqttClient.PendingApplicationMessagesCount == 0, 10000);
            
            Console.WriteLine($"Pending messages = {managedMqttClient.PendingApplicationMessagesCount}");
        }
    }
}