Use latest language features (#2176)

* Make use of language features line AsyncDispose, init etc.

* Fix build errors

* Improve Unit Tests

* Improve Unit Tests

* Improve Unit Tests

* Update samples

* Remove obsolete benchmarks

* Code cleanup

* Improve unit tests

* Improve Unit Tests

* Fix Unit Tests

* Improve Unit Tests

* Improve Unit Tests

* Restore unit tests

* Exclude load tests from unit tests

Samples/Client/Client_Connection_Samples.cs

@@ -413,7 +413,7 @@ m/XriWr/Cq4h/JfB7NTsezVslgkBaoU=
             if (e.ClientWasConnected)
             {
                 // Use the current options as the new options.
-                await mqttClient.ConnectAsync(mqttClient.Options);
+                await mqttClient.ConnectAsync(mqttClientOptions);
             }
         };
 

Samples/Client/Client_Publish_Samples.cs

@@ -23,25 +23,23 @@ public static class Client_Publish_Samples
 
         var mqttFactory = new MqttClientFactory();
 
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            var mqttClientOptions = new MqttClientOptionsBuilder()
-                .WithTcpServer("broker.hivemq.com")
-                .Build();
+        using var mqttClient = mqttFactory.CreateMqttClient();
+        var mqttClientOptions = new MqttClientOptionsBuilder()
+            .WithTcpServer("broker.hivemq.com")
+            .Build();
 
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+        await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
-            var applicationMessage = new MqttApplicationMessageBuilder()
-                .WithTopic("samples/temperature/living_room")
-                .WithPayload("19.5")
-                .Build();
+        var applicationMessage = new MqttApplicationMessageBuilder()
+            .WithTopic("samples/temperature/living_room")
+            .WithPayload("19.5")
+            .Build();
 
-            await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
+        await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
 
-            await mqttClient.DisconnectAsync();
+        await mqttClient.DisconnectAsync();
 
-            Console.WriteLine("MQTT application message is published.");
-        }
+        Console.WriteLine("MQTT application message is published.");
     }
 
     public static async Task Publish_Multiple_Application_Messages()
@@ -54,38 +52,36 @@ public static class Client_Publish_Samples
 
         var mqttFactory = new MqttClientFactory();
 
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            var mqttClientOptions = new MqttClientOptionsBuilder()
-                .WithTcpServer("broker.hivemq.com")
-                .Build();
+        using var mqttClient = mqttFactory.CreateMqttClient();
+        var mqttClientOptions = new MqttClientOptionsBuilder()
+            .WithTcpServer("broker.hivemq.com")
+            .Build();
 
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+        await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
-            var applicationMessage = new MqttApplicationMessageBuilder()
-                .WithTopic("samples/temperature/living_room")
-                .WithPayload("19.5")
-                .Build();
+        var applicationMessage = new MqttApplicationMessageBuilder()
+            .WithTopic("samples/temperature/living_room")
+            .WithPayload("19.5")
+            .Build();
 
-            await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
+        await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
 
-            applicationMessage = new MqttApplicationMessageBuilder()
-                .WithTopic("samples/temperature/living_room")
-                .WithPayload("20.0")
-                .Build();
+        applicationMessage = new MqttApplicationMessageBuilder()
+            .WithTopic("samples/temperature/living_room")
+            .WithPayload("20.0")
+            .Build();
 
-            await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
+        await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
 
-            applicationMessage = new MqttApplicationMessageBuilder()
-                .WithTopic("samples/temperature/living_room")
-                .WithPayload("21.0")
-                .Build();
+        applicationMessage = new MqttApplicationMessageBuilder()
+            .WithTopic("samples/temperature/living_room")
+            .WithPayload("21.0")
+            .Build();
 
-            await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
+        await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
 
-            await mqttClient.DisconnectAsync();
+        await mqttClient.DisconnectAsync();
 
-            Console.WriteLine("MQTT application message is published.");
-        }
+        Console.WriteLine("MQTT application message is published.");
     }
 }

Samples/Client/Client_Subscribe_Samples.cs

@@ -26,32 +26,30 @@ public static class Client_Subscribe_Samples
 
         var mqttFactory = new MqttClientFactory();
 
-        using (var mqttClient = mqttFactory.CreateMqttClient())
+        using var mqttClient = mqttFactory.CreateMqttClient();
+        var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
+
+        // Setup message handling before connecting so that queued messages
+        // are also handled properly. When there is no event handler attached all
+        // received messages get lost.
+        mqttClient.ApplicationMessageReceivedAsync += e =>
         {
-            var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
+            Console.WriteLine("Received application message.");
+            e.DumpToConsole();
 
-            // Setup message handling before connecting so that queued messages
-            // are also handled properly. When there is no event handler attached all
-            // received messages get lost.
-            mqttClient.ApplicationMessageReceivedAsync += e =>
-            {
-                Console.WriteLine("Received application message.");
-                e.DumpToConsole();
+            return Task.CompletedTask;
+        };
 
-                return Task.CompletedTask;
-            };
+        await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+        var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder().WithTopicTemplate(sampleTemplate.WithParameter("id", "2")).Build();
 
-            var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder().WithTopicTemplate(sampleTemplate.WithParameter("id", "2")).Build();
+        await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
 
-            await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
+        Console.WriteLine("MQTT client subscribed to topic.");
 
-            Console.WriteLine("MQTT client subscribed to topic.");
-
-            Console.WriteLine("Press enter to exit.");
-            Console.ReadLine();
-        }
+        Console.WriteLine("Press enter to exit.");
+        Console.ReadLine();
     }
 
     public static async Task Send_Responses()
@@ -62,36 +60,34 @@ public static class Client_Subscribe_Samples
 
         var mqttFactory = new MqttClientFactory();
 
-        using (var mqttClient = mqttFactory.CreateMqttClient())
+        using var mqttClient = mqttFactory.CreateMqttClient();
+        mqttClient.ApplicationMessageReceivedAsync += delegate(MqttApplicationMessageReceivedEventArgs args)
         {
-            mqttClient.ApplicationMessageReceivedAsync += delegate(MqttApplicationMessageReceivedEventArgs args)
-            {
-                // Do some work with the message...
+            // Do some work with the message...
 
-                // Now respond to the broker with a reason code other than success.
-                args.ReasonCode = MqttApplicationMessageReceivedReasonCode.ImplementationSpecificError;
-                args.ResponseReasonString = "That did not work!";
+            // Now respond to the broker with a reason code other than success.
+            args.ReasonCode = MqttApplicationMessageReceivedReasonCode.ImplementationSpecificError;
+            args.ResponseReasonString = "That did not work!";
 
-                // User properties require MQTT v5!
-                args.ResponseUserProperties.Add(new MqttUserProperty("My", "Data"));
+            // User properties require MQTT v5!
+            args.ResponseUserProperties.Add(new MqttUserProperty("My", "Data"));
 
-                // Now the broker will resend the message again.
-                return Task.CompletedTask;
-            };
+            // Now the broker will resend the message again.
+            return Task.CompletedTask;
+        };
 
-            var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
+        var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
 
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+        await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
-            var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder().WithTopicTemplate(sampleTemplate.WithParameter("id", "1")).Build();
+        var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder().WithTopicTemplate(sampleTemplate.WithParameter("id", "1")).Build();
 
-            var response = await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
+        var response = await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
 
-            Console.WriteLine("MQTT client subscribed to topic.");
+        Console.WriteLine("MQTT client subscribed to topic.");
 
-            // The response contains additional data sent by the server after subscribing.
-            response.DumpToConsole();
-        }
+        // The response contains additional data sent by the server after subscribing.
+        response.DumpToConsole();
     }
 
     public static async Task Subscribe_Multiple_Topics()
@@ -102,27 +98,25 @@ public static class Client_Subscribe_Samples
 
         var mqttFactory = new MqttClientFactory();
 
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
+        using var mqttClient = mqttFactory.CreateMqttClient();
+        var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
 
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+        await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
-            // Create the subscribe options including several topics with different options.
-            // It is also possible to all of these topics using a dedicated call of _SubscribeAsync_ per topic.
-            var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder()
-                .WithTopicTemplate(sampleTemplate.WithParameter("id", "1"))
-                .WithTopicTemplate(sampleTemplate.WithParameter("id", "2"), noLocal: true)
-                .WithTopicTemplate(sampleTemplate.WithParameter("id", "3"), retainHandling: MqttRetainHandling.SendAtSubscribe)
-                .Build();
+        // Create the subscribe options including several topics with different options.
+        // It is also possible to all of these topics using a dedicated call of _SubscribeAsync_ per topic.
+        var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder()
+            .WithTopicTemplate(sampleTemplate.WithParameter("id", "1"))
+            .WithTopicTemplate(sampleTemplate.WithParameter("id", "2"), noLocal: true)
+            .WithTopicTemplate(sampleTemplate.WithParameter("id", "3"), retainHandling: MqttRetainHandling.SendAtSubscribe)
+            .Build();
 
-            var response = await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
+        var response = await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
 
-            Console.WriteLine("MQTT client subscribed to topics.");
+        Console.WriteLine("MQTT client subscribed to topics.");
 
-            // The response contains additional data sent by the server after subscribing.
-            response.DumpToConsole();
-        }
+        // The response contains additional data sent by the server after subscribing.
+        response.DumpToConsole();
     }
 
     public static async Task Subscribe_Topic()
@@ -133,21 +127,19 @@ public static class Client_Subscribe_Samples
 
         var mqttFactory = new MqttClientFactory();
 
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
+        using var mqttClient = mqttFactory.CreateMqttClient();
+        var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
 
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+        await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
-            var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder().WithTopicTemplate(sampleTemplate.WithParameter("id", "1")).Build();
+        var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder().WithTopicTemplate(sampleTemplate.WithParameter("id", "1")).Build();
 
-            var response = await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
+        var response = await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
 
-            Console.WriteLine("MQTT client subscribed to topic.");
+        Console.WriteLine("MQTT client subscribed to topic.");
 
-            // The response contains additional data sent by the server after subscribing.
-            response.DumpToConsole();
-        }
+        // The response contains additional data sent by the server after subscribing.
+        response.DumpToConsole();
     }
 
     static void ConcurrentProcessingDisableAutoAcknowledge(CancellationToken shutdownToken, IMqttClient mqttClient)

Samples/Diagnostics/Logger_Samples.cs

@@ -26,17 +26,15 @@ public static class Logger_Samples
             .WithTcpServer("broker.hivemq.com")
             .Build();
 
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+        using var mqttClient = mqttFactory.CreateMqttClient();
+        await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
-            Console.WriteLine("MQTT client is connected.");
+        Console.WriteLine("MQTT client is connected.");
 
-            var mqttClientDisconnectOptions = mqttFactory.CreateClientDisconnectOptionsBuilder()
-                .Build();
+        var mqttClientDisconnectOptions = mqttFactory.CreateClientDisconnectOptionsBuilder()
+            .Build();
 
-            await mqttClient.DisconnectAsync(mqttClientDisconnectOptions, CancellationToken.None);
-        }
+        await mqttClient.DisconnectAsync(mqttClientDisconnectOptions, CancellationToken.None);
     }
 
     public static async Task Use_Event_Logger()
@@ -50,7 +48,7 @@ public static class Logger_Samples
         // The logger ID is optional but can be set do distinguish different logger instances.
         var mqttEventLogger = new MqttNetEventLogger("MyCustomLogger");
 
-        mqttEventLogger.LogMessagePublished += (sender, args) =>
+        mqttEventLogger.LogMessagePublished += (_, args) =>
         {
             var output = new StringBuilder();
             output.AppendLine($">> [{args.LogMessage.Timestamp:O}] [{args.LogMessage.ThreadId}] [{args.LogMessage.Source}] [{args.LogMessage.Level}]: {args.LogMessage.Message}");
@@ -68,17 +66,15 @@ public static class Logger_Samples
             .WithTcpServer("broker.hivemq.com")
             .Build();
 
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+        using var mqttClient = mqttFactory.CreateMqttClient();
+        await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
-            Console.WriteLine("MQTT client is connected.");
+        Console.WriteLine("MQTT client is connected.");
 
-            var mqttClientDisconnectOptions = mqttFactory.CreateClientDisconnectOptionsBuilder()
-                .Build();
+        var mqttClientDisconnectOptions = mqttFactory.CreateClientDisconnectOptionsBuilder()
+            .Build();
 
-            await mqttClient.DisconnectAsync(mqttClientDisconnectOptions, CancellationToken.None);
-        }
+        await mqttClient.DisconnectAsync(mqttClientDisconnectOptions, CancellationToken.None);
     }
 
     sealed class MyLogger : IMqttNetLogger

Samples/Diagnostics/PackageInspection_Samples.cs

@@ -20,23 +20,21 @@ public static class PackageInspection_Samples
 
         var mqttFactory = new MqttClientFactory();
 
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            var mqttClientOptions = mqttFactory.CreateClientOptionsBuilder()
-                .WithTcpServer("broker.hivemq.com")
-                .Build();
+        using var mqttClient = mqttFactory.CreateMqttClient();
+        var mqttClientOptions = mqttFactory.CreateClientOptionsBuilder()
+            .WithTcpServer("broker.hivemq.com")
+            .Build();
 
-            mqttClient.InspectPacketAsync += OnInspectPacket;
+        mqttClient.InspectPacketAsync += OnInspectPacket;
 
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+        await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
-            Console.WriteLine("MQTT client is connected.");
+        Console.WriteLine("MQTT client is connected.");
 
-            var mqttClientDisconnectOptions = mqttFactory.CreateClientDisconnectOptionsBuilder()
-                .Build();
+        var mqttClientDisconnectOptions = mqttFactory.CreateClientDisconnectOptionsBuilder()
+            .Build();
 
-            await mqttClient.DisconnectAsync(mqttClientDisconnectOptions, CancellationToken.None);
-        }
+        await mqttClient.DisconnectAsync(mqttClientDisconnectOptions, CancellationToken.None);
     }
 
     static Task OnInspectPacket(InspectMqttPacketEventArgs eventArgs)

Samples/RpcClient/RpcClient_Samples.cs

@@ -26,23 +26,21 @@ public static class RpcClient_Samples
         // The RPC client is an addon for the existing client. So we need a regular client
         // which is wrapped later.
 
-        using (var mqttClient = mqttFactory.CreateMqttClient())
+        using var mqttClient = mqttFactory.CreateMqttClient();
+        var mqttClientOptions = new MqttClientOptionsBuilder()
+            .WithTcpServer("broker.hivemq.com")
+            .Build();
+
+        await mqttClient.ConnectAsync(mqttClientOptions);
+
+        using (var mqttRpcClient = mqttFactory.CreateMqttRpcClient(mqttClient))
         {
-            var mqttClientOptions = new MqttClientOptionsBuilder()
-                .WithTcpServer("broker.hivemq.com")
-                .Build();
-
-            await mqttClient.ConnectAsync(mqttClientOptions);
-
-            using (var mqttRpcClient = mqttFactory.CreateMqttRpcClient(mqttClient))
-            {
-                // Access to a fully featured application message is not supported for RPC calls!
-                // The method will throw an exception when the response was not received in time.
-                await mqttRpcClient.ExecuteAsync(TimeSpan.FromSeconds(2), "ping", "", MqttQualityOfServiceLevel.AtMostOnce);
-            }
-
-            Console.WriteLine("The RPC call was successful.");
+            // Access to a fully featured application message is not supported for RPC calls!
+            // The method will throw an exception when the response was not received in time.
+            await mqttRpcClient.ExecuteAsync(TimeSpan.FromSeconds(2), "ping", "", MqttQualityOfServiceLevel.AtMostOnce);
         }
+
+        Console.WriteLine("The RPC call was successful.");
     }
 
     /*

Samples/Server/Server_Diagnostics_Samples.cs

@@ -25,28 +25,26 @@ public static class Server_Diagnostics_Samples
         var mqttServerFactory = new MqttServerFactory();
         var mqttServerOptions = new MqttServerOptionsBuilder().WithDefaultEndpoint().Build();
 
-        using (var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions))
+        using var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions);
+        // Attach the event handler.
+        mqttServer.ClientAcknowledgedPublishPacketAsync += e =>
         {
-            // Attach the event handler.
-            mqttServer.ClientAcknowledgedPublishPacketAsync += e =>
-            {
-                Console.WriteLine($"Client '{e.ClientId}' acknowledged packet {e.PublishPacket.PacketIdentifier} with topic '{e.PublishPacket.Topic}'");
+            Console.WriteLine($"Client '{e.ClientId}' acknowledged packet {e.PublishPacket.PacketIdentifier} with topic '{e.PublishPacket.Topic}'");
 
-                // It is also possible to read additional data from the client response. This requires casting the response packet.
-                var qos1AcknowledgePacket = e.AcknowledgePacket as MqttPubAckPacket;
-                Console.WriteLine($"QoS 1 reason code: {qos1AcknowledgePacket?.ReasonCode}");
+            // It is also possible to read additional data from the client response. This requires casting the response packet.
+            var qos1AcknowledgePacket = e.AcknowledgePacket as MqttPubAckPacket;
+            Console.WriteLine($"QoS 1 reason code: {qos1AcknowledgePacket?.ReasonCode}");
 
-                var qos2AcknowledgePacket = e.AcknowledgePacket as MqttPubCompPacket;
-                Console.WriteLine($"QoS 2 reason code: {qos1AcknowledgePacket?.ReasonCode}");
-                return CompletedTask.Instance;
-            };
+            var qos2AcknowledgePacket = e.AcknowledgePacket as MqttPubCompPacket;
+            Console.WriteLine($"QoS 2 reason code: {qos2AcknowledgePacket?.ReasonCode}");
+            return CompletedTask.Instance;
+        };
 
-            await mqttServer.StartAsync();
+        await mqttServer.StartAsync();
 
-            Console.WriteLine("Press Enter to exit.");
-            Console.ReadLine();
+        Console.WriteLine("Press Enter to exit.");
+        Console.ReadLine();
 
-            await mqttServer.StopAsync();
-        }
+        await mqttServer.StopAsync();
     }
 }

Samples/Server/Server_Intercepting_Samples.cs

@@ -25,23 +25,21 @@ public static class Server_Intercepting_Samples
         var mqttServerFactory = new MqttServerFactory();
         var mqttServerOptions = new MqttServerOptionsBuilder().WithDefaultEndpoint().Build();
 
-        using (var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions))
+        using var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions);
+        mqttServer.InterceptingPublishAsync += args =>
         {
-            mqttServer.InterceptingPublishAsync += args =>
-            {
-                // Here we only change the topic of the received application message.
-                // but also changing the payload etc. is required. Changing the QoS after
-                // transmitting is not supported and makes no sense at all.
-                args.ApplicationMessage.Topic += "/manipulated";
+            // Here we only change the topic of the received application message.
+            // but also changing the payload etc. is required. Changing the QoS after
+            // transmitting is not supported and makes no sense at all.
+            args.ApplicationMessage.Topic += "/manipulated";
 
-                return CompletedTask.Instance;
-            };
+            return CompletedTask.Instance;
+        };
 
-            await mqttServer.StartAsync();
+        await mqttServer.StartAsync();
 
-            Console.WriteLine("Press Enter to exit.");
-            Console.ReadLine();
-            await mqttServer.StopAsync();
-        }
+        Console.WriteLine("Press Enter to exit.");
+        Console.ReadLine();
+        await mqttServer.StopAsync();
     }
 }

Samples/Server/Server_Retained_Messages_Samples.cs

@@ -29,64 +29,62 @@ public static class Server_Retained_Messages_Samples
         // Due to security reasons the "default" endpoint (which is unencrypted) is not enabled by default!
         var mqttServerOptions = mqttServerFactory.CreateServerOptionsBuilder().WithDefaultEndpoint().Build();
 
-        using (var server = mqttServerFactory.CreateMqttServer(mqttServerOptions))
+        using var server = mqttServerFactory.CreateMqttServer(mqttServerOptions);
+        // Make sure that the server will load the retained messages.
+        server.LoadingRetainedMessageAsync += async eventArgs =>
         {
-            // Make sure that the server will load the retained messages.
-            server.LoadingRetainedMessageAsync += async eventArgs =>
+            try
             {
-                try
-                {
-                    var models = await JsonSerializer.DeserializeAsync<List<MqttRetainedMessageModel>>(File.OpenRead(storePath)) ?? new List<MqttRetainedMessageModel>();
-                    var retainedMessages = models.Select(m => m.ToApplicationMessage()).ToList();
+                var models = await JsonSerializer.DeserializeAsync<List<MqttRetainedMessageModel>>(File.OpenRead(storePath)) ?? new List<MqttRetainedMessageModel>();
+                var retainedMessages = models.Select(m => m.ToApplicationMessage()).ToList();
 
-                    eventArgs.LoadedRetainedMessages = retainedMessages;
-                    Console.WriteLine("Retained messages loaded.");
-                }
-                catch (FileNotFoundException)
-                {
-                    // Ignore because nothing is stored yet.
-                    Console.WriteLine("No retained messages stored yet.");
-                }
-                catch (Exception exception)
-                {
-                    Console.WriteLine(exception);
-                }
-            };
-
-            // Make sure to persist the changed retained messages.
-            server.RetainedMessageChangedAsync += async eventArgs =>
+                eventArgs.LoadedRetainedMessages = retainedMessages;
+                Console.WriteLine("Retained messages loaded.");
+            }
+            catch (FileNotFoundException)
             {
-                try
-                {
-                    // This sample uses the property _StoredRetainedMessages_ which will contain all(!) retained messages.
-                    // The event args also contain the affected retained message (property ChangedRetainedMessage). This can be
-                    // used to write all retained messages to dedicated files etc. Then all files must be loaded and a full list
-                    // of retained messages must be provided in the loaded event.
-
-                    var models = eventArgs.StoredRetainedMessages.Select(MqttRetainedMessageModel.Create);
-
-                    var buffer = JsonSerializer.SerializeToUtf8Bytes(models);
-                    await File.WriteAllBytesAsync(storePath, buffer);
-                    Console.WriteLine("Retained messages saved.");
-                }
-                catch (Exception exception)
-                {
-                    Console.WriteLine(exception);
-                }
-            };
-
-            // Make sure to clear the retained messages when they are all deleted via API.
-            server.RetainedMessagesClearedAsync += _ =>
+                // Ignore because nothing is stored yet.
+                Console.WriteLine("No retained messages stored yet.");
+            }
+            catch (Exception exception)
             {
-                File.Delete(storePath);
-                return Task.CompletedTask;
-            };
+                Console.WriteLine(exception);
+            }
+        };
 
-            await server.StartAsync();
+        // Make sure to persist the changed retained messages.
+        server.RetainedMessageChangedAsync += async eventArgs =>
+        {
+            try
+            {
+                // This sample uses the property _StoredRetainedMessages_ which will contain all(!) retained messages.
+                // The event args also contain the affected retained message (property ChangedRetainedMessage). This can be
+                // used to write all retained messages to dedicated files etc. Then all files must be loaded and a full list
+                // of retained messages must be provided in the loaded event.
 
-            Console.WriteLine("Press Enter to exit.");
-            Console.ReadLine();
-        }
+                var models = eventArgs.StoredRetainedMessages.Select(MqttRetainedMessageModel.Create);
+
+                var buffer = JsonSerializer.SerializeToUtf8Bytes(models);
+                await File.WriteAllBytesAsync(storePath, buffer);
+                Console.WriteLine("Retained messages saved.");
+            }
+            catch (Exception exception)
+            {
+                Console.WriteLine(exception);
+            }
+        };
+
+        // Make sure to clear the retained messages when they are all deleted via API.
+        server.RetainedMessagesClearedAsync += _ =>
+        {
+            File.Delete(storePath);
+            return Task.CompletedTask;
+        };
+
+        await server.StartAsync();
+
+        Console.WriteLine("Press Enter to exit.");
+        Console.ReadLine();
     }
 
     sealed class MqttRetainedMessageModel

Samples/Server/Server_Simple_Samples.cs

@@ -22,17 +22,15 @@ public static class Server_Simple_Samples
          * See _Run_Minimal_Server_ for more information.
          */
 
-        using (var mqttServer = await StartMqttServer())
-        {
-            // Let the client connect.
-            await Task.Delay(TimeSpan.FromSeconds(5));
+        using var mqttServer = await StartMqttServer();
+        // Let the client connect.
+        await Task.Delay(TimeSpan.FromSeconds(5));
 
-            // Now disconnect the client (if connected).
-            var affectedClient = (await mqttServer.GetClientsAsync()).FirstOrDefault(c => c.Id == "MyClient");
-            if (affectedClient != null)
-            {
-                await affectedClient.DisconnectAsync();
-            }
+        // Now disconnect the client (if connected).
+        var affectedClient = (await mqttServer.GetClientsAsync()).FirstOrDefault(c => c.Id == "MyClient");
+        if (affectedClient != null)
+        {
+            await affectedClient.DisconnectAsync();
         }
     }
 
@@ -44,18 +42,16 @@ public static class Server_Simple_Samples
          * See _Run_Minimal_Server_ for more information.
          */
 
-        using (var mqttServer = await StartMqttServer())
-        {
-            // Create a new message using the builder as usual.
-            var message = new MqttApplicationMessageBuilder().WithTopic("HelloWorld").WithPayload("Test").Build();
+        using var mqttServer = await StartMqttServer();
+        // Create a new message using the builder as usual.
+        var message = new MqttApplicationMessageBuilder().WithTopic("HelloWorld").WithPayload("Test").Build();
 
-            // Now inject the new message at the broker.
-            await mqttServer.InjectApplicationMessage(
-                new InjectedMqttApplicationMessage(message)
-                {
-                    SenderClientId = "SenderClientId"
-                });
-        }
+        // Now inject the new message at the broker.
+        await mqttServer.InjectApplicationMessage(
+            new InjectedMqttApplicationMessage(message)
+            {
+                SenderClientId = "SenderClientId"
+            });
     }
 
     public static async Task Run_Minimal_Server()
@@ -77,16 +73,14 @@ public static class Server_Simple_Samples
         //     .WithDefaultEndpointPort(1234)
         //     .Build();
 
-        using (var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions))
-        {
-            await mqttServer.StartAsync();
+        using var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions);
+        await mqttServer.StartAsync();
 
-            Console.WriteLine("Press Enter to exit.");
-            Console.ReadLine();
+        Console.WriteLine("Press Enter to exit.");
+        Console.ReadLine();
 
-            // Stop and dispose the MQTT server if it is no longer needed!
-            await mqttServer.StopAsync();
-        }
+        // Stop and dispose the MQTT server if it is no longer needed!
+        await mqttServer.StopAsync();
     }
 
     public static async Task Run_Server_With_Logging()
@@ -103,16 +97,14 @@ public static class Server_Simple_Samples
 
         var mqttServerOptions = new MqttServerOptionsBuilder().WithDefaultEndpoint().Build();
 
-        using (var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions))
-        {
-            await mqttServer.StartAsync();
+        using var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions);
+        await mqttServer.StartAsync();
 
-            Console.WriteLine("Press Enter to exit.");
-            Console.ReadLine();
+        Console.WriteLine("Press Enter to exit.");
+        Console.ReadLine();
 
-            // Stop and dispose the MQTT server if it is no longer needed!
-            await mqttServer.StopAsync();
-        }
+        // Stop and dispose the MQTT server if it is no longer needed!
+        await mqttServer.StopAsync();
     }
 
     public static async Task Validating_Connections()
@@ -127,37 +119,35 @@ public static class Server_Simple_Samples
 
         var mqttServerOptions = new MqttServerOptionsBuilder().WithDefaultEndpoint().Build();
 
-        using (var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions))
+        using var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions);
+        // Setup connection validation before starting the server so that there is
+        // no change to connect without valid credentials.
+        mqttServer.ValidatingConnectionAsync += e =>
         {
-            // Setup connection validation before starting the server so that there is
-            // no change to connect without valid credentials.
-            mqttServer.ValidatingConnectionAsync += e =>
+            if (e.ClientId != "ValidClientId")
             {
-                if (e.ClientId != "ValidClientId")
-                {
-                    e.ReasonCode = MqttConnectReasonCode.ClientIdentifierNotValid;
-                }
+                e.ReasonCode = MqttConnectReasonCode.ClientIdentifierNotValid;
+            }
 
-                if (e.UserName != "ValidUser")
-                {
-                    e.ReasonCode = MqttConnectReasonCode.BadUserNameOrPassword;
-                }
+            if (e.UserName != "ValidUser")
+            {
+                e.ReasonCode = MqttConnectReasonCode.BadUserNameOrPassword;
+            }
 
-                if (e.Password != "SecretPassword")
-                {
-                    e.ReasonCode = MqttConnectReasonCode.BadUserNameOrPassword;
-                }
+            if (e.Password != "SecretPassword")
+            {
+                e.ReasonCode = MqttConnectReasonCode.BadUserNameOrPassword;
+            }
 
-                return Task.CompletedTask;
-            };
+            return Task.CompletedTask;
+        };
 
-            await mqttServer.StartAsync();
+        await mqttServer.StartAsync();
 
-            Console.WriteLine("Press Enter to exit.");
-            Console.ReadLine();
+        Console.WriteLine("Press Enter to exit.");
+        Console.ReadLine();
 
-            await mqttServer.StopAsync();
-        }
+        await mqttServer.StopAsync();
     }
 
     static async Task<MqttServer> StartMqttServer()

Samples/Server/Server_TLS_Samples.cs

@@ -31,16 +31,14 @@ public static class Server_TLS_Samples
 
         var mqttServerOptions = new MqttServerOptionsBuilder().WithEncryptionCertificate(certificate).WithEncryptedEndpoint().Build();
 
-        using (var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions))
-        {
-            await mqttServer.StartAsync();
+        using var mqttServer = mqttServerFactory.CreateMqttServer(mqttServerOptions);
+        await mqttServer.StartAsync();
 
-            Console.WriteLine("Press Enter to exit.");
-            Console.ReadLine();
+        Console.WriteLine("Press Enter to exit.");
+        Console.ReadLine();
 
-            // Stop and dispose the MQTT server if it is no longer needed!
-            await mqttServer.StopAsync();
-        }
+        // Stop and dispose the MQTT server if it is no longer needed!
+        await mqttServer.StopAsync();
     }
 
     static X509Certificate2 CreateSelfSignedCertificate(string oid)
@@ -50,26 +48,22 @@ public static class Server_TLS_Samples
         sanBuilder.AddIpAddress(IPAddress.IPv6Loopback);
         sanBuilder.AddDnsName("localhost");
 
-        using (var rsa = RSA.Create())
-        {
-            var certRequest = new CertificateRequest("CN=localhost", rsa, HashAlgorithmName.SHA512, RSASignaturePadding.Pkcs1);
+        using var rsa = RSA.Create();
+        var certRequest = new CertificateRequest("CN=localhost", rsa, HashAlgorithmName.SHA512, RSASignaturePadding.Pkcs1);
 
-            certRequest.CertificateExtensions.Add(
-                new X509KeyUsageExtension(X509KeyUsageFlags.DataEncipherment | X509KeyUsageFlags.KeyEncipherment | X509KeyUsageFlags.DigitalSignature, false));
+        certRequest.CertificateExtensions.Add(
+            new X509KeyUsageExtension(X509KeyUsageFlags.DataEncipherment | X509KeyUsageFlags.KeyEncipherment | X509KeyUsageFlags.DigitalSignature, false));
 
-            certRequest.CertificateExtensions.Add(new X509EnhancedKeyUsageExtension(new OidCollection { new(oid) }, false));
+        certRequest.CertificateExtensions.Add(new X509EnhancedKeyUsageExtension(new OidCollection { new(oid) }, false));
 
-            certRequest.CertificateExtensions.Add(sanBuilder.Build());
+        certRequest.CertificateExtensions.Add(sanBuilder.Build());
 
-            using (var certificate = certRequest.CreateSelfSigned(DateTimeOffset.Now.AddMinutes(-10), DateTimeOffset.Now.AddMinutes(10)))
-            {
-                var pfxCertificate = new X509Certificate2(
-                    certificate.Export(X509ContentType.Pfx),
-                    (string)null!,
-                    X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.Exportable);
+        using var certificate = certRequest.CreateSelfSigned(DateTimeOffset.Now.AddMinutes(-10), DateTimeOffset.Now.AddMinutes(10));
+        var pfxCertificate = new X509Certificate2(
+            certificate.Export(X509ContentType.Pfx),
+            (string)null!,
+            X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.Exportable);
 
-                return pfxCertificate;
-            }
-        }
+        return pfxCertificate;
     }
 }