1862 Add subscribe and unsubscribe results event for Managed Mqtt Client. (#1894)

* See the issue #1862 Adding an event when ManagedMqttClient actually subscribe/unsubscribe to topics. This event has to be used in parallel with connected event to know the exact state. * Rename SubscriptionsResultAsync to SubscriptionsChangedAsync. * Rename internal field for event * Update ReleaseNotes.md --------- Co-authored-by: Pierre Dufrene <pierre.dufrene@se.com> Co-authored-by: Christian <6939810+chkr1011@users.noreply.github.com>
2026-10-16 01:03:01 +08:00 · 2024-03-02 09:58:42 +01:00
parent 1245d8299a
commit aabf180b23
5 changed files with 155 additions and 11 deletions
@@ -0,0 +1,87 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+// ReSharper disable UnusedType.Global
+// ReSharper disable UnusedMember.Global
+// ReSharper disable InconsistentNaming
+
+using MQTTnet.Client;
+using MQTTnet.Extensions.ManagedClient;
+
+namespace MQTTnet.Samples.ManagedClient;
+
+public sealed class Managed_Client_Subscribe_Samples
+{
+    public static async Task Connect_Client()
+    {
+        /*
+         * This sample creates a simple managed MQTT client and connects to a public broker, subscribe to a topic and verifies subscription result.
+         *
+         * 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();
+        var subscribed = false;
+
+        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($"Pending messages = {managedMqttClient.PendingApplicationMessagesCount}");
+
+            managedMqttClient.SubscriptionsChangedAsync += args => SubscriptionsResultAsync(args, subscribed);
+            await managedMqttClient.SubscribeAsync("Topic").ConfigureAwait(false);
+
+            SpinWait.SpinUntil(() => subscribed, 1000);
+            Console.WriteLine("Subscription properly done");
+        }
+    }
+
+    private static Task SubscriptionsResultAsync(SubscriptionsChangedEventArgs arg, bool subscribed)
+    {
+        foreach (var mqttClientSubscribeResult in arg.SubscribeResult)
+        {
+            Console.WriteLine($"Subscription reason {mqttClientSubscribeResult.ReasonString}");
+            foreach (var item in mqttClientSubscribeResult.Items)
+            {
+                Console.WriteLine($"For topic filter {item.TopicFilter}, result code: {item.ResultCode}");
+
+                if (item.TopicFilter.Topic == "Topic" && item.ResultCode == MqttClientSubscribeResultCode.GrantedQoS0 && !subscribed)
+                {
+                    subscribed = true;
+                }
+            }
+        }
+
+        foreach (var mqttClientUnsubscribeResult in arg.UnsubscribeResult)
+        {
+            Console.WriteLine($"Unsubscription reason {mqttClientUnsubscribeResult.ReasonString}");
+            foreach (var item in mqttClientUnsubscribeResult.Items)
+            {
+                Console.WriteLine($"For topic filter {item.TopicFilter}, result code: {item.ResultCode}");
+            }
+        }
+
+        return Task.CompletedTask;
+    }
+}