Add samples.

.github/workflows/ReleaseNotes.md

@@ -1,9 +0,0 @@
-* [Core] Fixed a memory leak in _AsyncSignal_ implementation (#1586, thanks to @mario-zelger).
-* [Core] Fixed an issue with bounds handling in _MqttBufferReader_ (#1593).
-* [Core] Performance improvements and reduced memory usage due to improved buffer copies (#1599, thanks to @xljiulang).
-* [Server] Fix not properly reset statistics (#1587, thanks to @damikun).
-* [Server] Now using an empty string as the sender client ID for injected application messages (#1583, thanks to @xljiulang).
-* [Server] Improved memory usage for ASP.NET connections (#1582, thanks to @xljiulang).
-* [Server] Improved memory usage and performance for ASP.NET integration (#1596, thanks to @xljiulang).
-* [Server] Add support for interception of will messages (#1613).
-* [Server] Fixed wrong topic filter detections (#1615, thanks to @logicaloud).

.github/workflows/ci.yml

@@ -3,7 +3,7 @@ name: CI
 on: [push, pull_request]
 
 env:
-  VERSION: "4.1.4.${{github.run_number}}"
+  VERSION: "4.1.0.${{github.run_number}}"
 
 jobs:
   build:
@@ -61,3 +61,7 @@ jobs:
       - name: Publish MyGet nugets
         if: ${{ github.event_name == 'push' }}
         run: dotnet nuget push **/*.nupkg -k ${{ secrets.MYGET_API_KEY }} -s https://www.myget.org/F/mqttnet/api/v3/index.json --skip-duplicate
+
+#      - name: Publish nugets
+#        if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/master' }}
+#        run: dotnet nuget push **/*.nupkg -k ${{ secrets.NUGET_API_KEY }} -s https://api.nuget.org/v3/index.json --skip-duplicate

MQTTnet.sln.DotSettings

@@ -210,7 +210,6 @@
         </Or>
       </Entry.Match>
         <Entry.SortBy>
-            <Access Order="Public Internal Protected Private" />
             <Name />
         </Entry.SortBy>
     </Entry>
@@ -240,14 +239,6 @@ See the LICENSE file in the project root for more information.</s:String>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002ECSharpPlaceAttributeOnSameLineMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002EMigrateBlankLinesAroundFieldToBlankLinesAroundProperty/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002EMigrateThisQualifierSettings/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/UserDictionary/Words/=CONNACK/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=PINGREQ/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/UserDictionary/Words/=PINGRESP/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/UserDictionary/Words/=PUBACK/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/UserDictionary/Words/=PUBCOMP/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/UserDictionary/Words/=PUBREC/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/UserDictionary/Words/=PUBREL/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/UserDictionary/Words/=SUBACK/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Tnet/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/UserDictionary/Words/=unsub/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=unsub/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>
-	<s:Boolean x:Key="/Default/UserDictionary/Words/=UNSUBACK/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>

README.md

@@ -4,7 +4,7 @@
 </p>
 
 [![NuGet Badge](https://buildstats.info/nuget/MQTTnet)](https://www.nuget.org/packages/MQTTnet)
-[![CI](https://github.com/dotnet/MQTTnet/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/dotnet/MQTTnet/actions/workflows/ci.yml)
+[![CI](https://github.com/dotnet/MQTTnet/actions/workflows/ci.yml/badge.svg)](https://github.com/dotnet/MQTTnet/actions/workflows/ci.yml)
 [![MyGet](https://img.shields.io/myget/mqttnet/v/mqttnet?color=orange&label=MyGet-Preview)](https://www.myget.org/feed/mqttnet/package/nuget/MQTTnet)
 ![Size](https://img.shields.io/github/repo-size/dotnet/MQTTnet.svg)
 [![Join the chat at https://gitter.im/MQTTnet/community](https://badges.gitter.im/MQTTnet/community.svg)](https://gitter.im/MQTTnet/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
@@ -12,7 +12,7 @@
 
 # MQTTnet
 
-MQTTnet is a high performance .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker) and supports the MQTT protocol up to version 5. It is compatible with mostly any supported .NET Framework version and CPU architecture.
+MQTTnet is a high performance .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker) and supports the MQTT protocol up to version 5.
 
 ## Features
 
@@ -50,6 +50,39 @@ MQTTnet is a high performance .NET library for MQTT based communication. It prov
 * A custom message interceptor can be added which allows transforming or extending every received application message
 * Validate subscriptions and deny subscribing of certain topics depending on requesting clients
 
+## Supported frameworks
+
+| Framwork           | Version     |
+| ------------------ | ----------- |
+|.NET                | 5.0+        |
+|.NET Framework      | 4.5.2+      |
+|.NET Standard       | 1.3+        |
+|.NET Core           | 1.1+        |
+|.NET Core App       | 1.1+        |
+| Mono               | 5.2+        |
+| UWP                | 10.0.10240+ |
+| Xamarin.Android    | 7.5+        |
+| Xamarin.iOS        | 10.14+      |
+| Blazor WebAssembly | 3.2.0+      |
+
+## References
+
+This library is used in the following projects:
+
+* Azure Functions MQTT Bindings, <https://github.com/keesschollaart81/CaseOnline.Azure.WebJobs.Extensions.Mqtt>)
+* HA4IoT (Open Source Home Automation system for .NET, <https://github.com/chkr1011/HA4IoT>)
+* MQTT Client Rx (Wrapper for Reactive Extensions, <https://github.com/1iveowl/MQTTClient.rx>)
+* MQTT Client Rx (Managed Client Wrapper for Reactive Extensions, <https://github.com/mmuecke/RxMQTTnet>)
+* MQTT Tester (MQTT client test app for [Android](https://play.google.com/store/apps/details?id=com.liveowl.mqtttester) and [iOS](https://itunes.apple.com/us/app/mqtt-tester/id1278621826?mt=8))
+* MQTTnet App (Cross platform client application for MQTT debugging, inspection etc., <https://github.com/chkr1011/MQTTnetApp>)
+* Wirehome.Core (Open Source Home Automation system for .NET Core, <https://github.com/chkr1011/Wirehome.Core>)
+* SparkplugNet (Sparkplug library for .Net, <https://github.com/SeppPenner/SparkplugNet>)
+* Silverback (Framework to build event-driven applications - support for MQTT, Kafka & RabbitMQ) <https://github.com/BEagle1984/silverback>
+
+Further projects using this project can be found under https://github.com/dotnet/MQTTnet/network/dependents.
+
+If you use this library and want to see your project here please create a pull request.
+
 ## Code of Conduct
 
 This project has adopted the code of conduct defined by the Contributor Covenant to clarify expected behavior in our community.

Samples/Client/Client_Connection_Samples.cs

@@ -10,7 +10,7 @@ using System.Security.Authentication;
 using MQTTnet.Client;
 using MQTTnet.Extensions.WebSocket4Net;
 using MQTTnet.Formatter;
-using MQTTnet.Samples.Helpers;
+using MQTTnet.Samples.Shared;
 
 namespace MQTTnet.Samples.Client;
 
@@ -134,17 +134,15 @@ public static class Client_Connection_Samples
         }
     }
 
-    public static async Task Connect_Client_Using_WebSocket4Net()
+    public static async Task Connect_Client_Using_WebSockets()
     {
         /*
          * This sample creates a simple MQTT client and connects to a public broker using a WebSocket connection.
-         * Instead of the .NET implementation of WebSockets the implementation from WebSocket4Net is used. It provides more
-         * encryption algorithms and supports more platforms.
          * 
          * This is a modified version of the sample _Connect_Client_! See other sample for more details.
          */
 
-        var mqttFactory = new MqttFactory().UseWebSocket4Net();
+        var mqttFactory = new MqttFactory();
 
         using (var mqttClient = mqttFactory.CreateMqttClient())
         {
@@ -158,15 +156,17 @@ public static class Client_Connection_Samples
         }
     }
     
-    public static async Task Connect_Client_Using_WebSockets()
+    public static async Task Connect_Client_Using_WebSocket4Net()
     {
         /*
          * This sample creates a simple MQTT client and connects to a public broker using a WebSocket connection.
+         * Instead of the .NET implementation of WebSockets the implementaion from WebSocket4Net is used. It provides more
+         * encryption algorithms and supports more platforms.
          * 
          * This is a modified version of the sample _Connect_Client_! See other sample for more details.
          */
 
-        var mqttFactory = new MqttFactory();
+        var mqttFactory = new MqttFactory().UseWebSocket4Net();
 
         using (var mqttClient = mqttFactory.CreateMqttClient())
         {
@@ -214,49 +214,6 @@ public static class Client_Connection_Samples
         }
     }
 
-    public static async Task Disconnect_Clean()
-    {
-        /*
-         * This sample disconnects from the server with sending a DISCONNECT packet.
-         * This way of disconnecting is treated as a clean disconnect which will not
-         * trigger sending the last will etc.
-         */
-
-        var mqttFactory = new MqttFactory();
-
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
-
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
-
-            // Calling _DisconnectAsync_ will send a DISCONNECT packet before closing the connection.
-            // Using a reason code requires MQTT version 5.0.0!
-            await mqttClient.DisconnectAsync(MqttClientDisconnectReason.ImplementationSpecificError);
-        }
-    }
-
-    public static async Task Disconnect_Non_Clean()
-    {
-        /*
-         * This sample disconnects from the server without sending a DISCONNECT packet.
-         * This way of disconnecting is treated as a non clean disconnect which will
-         * trigger sending the last will etc.
-         */
-
-        var mqttFactory = new MqttFactory();
-
-        var mqttClient = mqttFactory.CreateMqttClient();
-
-        var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
-
-        await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
-
-        // Calling _Dispose_ or use of a _using_ statement will close the transport connection
-        // without sending a DISCONNECT packet to the server.
-        mqttClient.Dispose();
-    }
-
     public static async Task Inspect_Certificate_Validation_Errors()
     {
         /*
@@ -364,12 +321,14 @@ public static class Client_Connection_Samples
                     {
                         try
                         {
-                            // This code will also do the very first connect! So no call to _ConnectAsync_ is required in the first place.
+                            // This code will also do the very first connect! So no call to _ConnectAsync_ is required
-                            if (!await mqttClient.TryPingAsync())
+                            // in the first place.
+                            if (!mqttClient.IsConnected)
                             {
                                 await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
                                 // Subscribe to topics when session is clean etc.
+
                                 Console.WriteLine("The MQTT client is connected.");
                             }
                         }

Samples/Client/Client_Publish_Samples.cs

@@ -40,53 +40,6 @@ public static class Client_Publish_Samples
 
             await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
 
-            await mqttClient.DisconnectAsync();
-            
-            Console.WriteLine("MQTT application message is published.");
-        }
-    }
-    
-    public static async Task Publish_Multiple_Application_Messages()
-    {
-        /*
-         * This sample pushes multiple simple application message including a topic and a payload.
-         *
-         * See sample _Publish_Application_Message_ for more details.
-         */
-
-        var mqttFactory = new MqttFactory();
-
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            var mqttClientOptions = new MqttClientOptionsBuilder()
-                .WithTcpServer("broker.hivemq.com")
-                .Build();
-
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
-
-            var applicationMessage = new MqttApplicationMessageBuilder()
-                .WithTopic("samples/temperature/living_room")
-                .WithPayload("19.5")
-                .Build();
-
-            await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
-            
-            applicationMessage = new MqttApplicationMessageBuilder()
-                .WithTopic("samples/temperature/living_room")
-                .WithPayload("20.0")
-                .Build();
-            
-            await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
-
-            applicationMessage = new MqttApplicationMessageBuilder()
-                .WithTopic("samples/temperature/living_room")
-                .WithPayload("21.0")
-                .Build();
-            
-            await mqttClient.PublishAsync(applicationMessage, CancellationToken.None);
-
-            await mqttClient.DisconnectAsync();
-            
             Console.WriteLine("MQTT application message is published.");
         }
     }

Samples/Client/Client_Subscribe_Samples.cs

@@ -7,9 +7,7 @@
 // ReSharper disable InconsistentNaming
 
 using MQTTnet.Client;
-using MQTTnet.Packets;
+using MQTTnet.Samples.Shared;
-using MQTTnet.Protocol;
-using MQTTnet.Samples.Helpers;
 
 namespace MQTTnet.Samples.Client;
 
@@ -25,7 +23,9 @@ public static class Client_Subscribe_Samples
 
         using (var mqttClient = mqttFactory.CreateMqttClient())
         {
-            var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
+            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
@@ -41,11 +41,7 @@ public static class Client_Subscribe_Samples
             await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
             var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder()
-                .WithTopicFilter(
+                .WithTopicFilter(f => { f.WithTopic("mqttnet/samples/topic/2"); })
-                    f =>
-                    {
-                        f.WithTopic("mqttnet/samples/topic/2");
-                    })
                 .Build();
 
             await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
@@ -57,95 +53,6 @@ public static class Client_Subscribe_Samples
         }
     }
 
-    public static async Task Send_Responses()
-    {
-        /*
-         * This sample subscribes to a topic and sends a response to the broker. This requires at least QoS level 1 to work!
-         */
-
-        var mqttFactory = new MqttFactory();
-
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            mqttClient.ApplicationMessageReceivedAsync += delegate(MqttApplicationMessageReceivedEventArgs args)
-            {
-                // 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!";
-
-                // User properties require MQTT v5!
-                args.ResponseUserProperties.Add(new MqttUserProperty("My", "Data"));
-
-                // Now the broker will resend the message again.
-                return Task.CompletedTask;
-            };
-
-            var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
-
-            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
-
-            var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder()
-                .WithTopicFilter(
-                    f =>
-                    {
-                        f.WithTopic("mqttnet/samples/topic/1");
-                    })
-                .Build();
-
-            var response = await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
-
-            Console.WriteLine("MQTT client subscribed to topic.");
-
-            // The response contains additional data sent by the server after subscribing.
-            response.DumpToConsole();
-        }
-    }
-
-    public static async Task Subscribe_Multiple_Topics()
-    {
-        /*
-         * This sample subscribes to several topics in a single request.
-         */
-
-        var mqttFactory = new MqttFactory();
-
-        using (var mqttClient = mqttFactory.CreateMqttClient())
-        {
-            var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
-
-            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()
-                .WithTopicFilter(
-                    f =>
-                    {
-                        f.WithTopic("mqttnet/samples/topic/1");
-                    })
-                .WithTopicFilter(
-                    f =>
-                    {
-                        f.WithTopic("mqttnet/samples/topic/2").WithNoLocal();
-                    })
-                .WithTopicFilter(
-                    f =>
-                    {
-                        f.WithTopic("mqttnet/samples/topic/3").WithRetainHandling(MqttRetainHandling.SendAtSubscribe);
-                    })
-                .Build();
-
-            var response = await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
-
-            Console.WriteLine("MQTT client subscribed to topics.");
-
-            // The response contains additional data sent by the server after subscribing.
-            response.DumpToConsole();
-        }
-    }
-
     public static async Task Subscribe_Topic()
     {
         /*
@@ -156,16 +63,14 @@ public static class Client_Subscribe_Samples
 
         using (var mqttClient = mqttFactory.CreateMqttClient())
         {
-            var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
+            var mqttClientOptions = new MqttClientOptionsBuilder()
+                .WithTcpServer("broker.hivemq.com")
+                .Build();
 
             await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
 
             var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder()
-                .WithTopicFilter(
+                .WithTopicFilter(f => { f.WithTopic("mqttnet/samples/topic/1"); })
-                    f =>
-                    {
-                        f.WithTopic("mqttnet/samples/topic/1");
-                    })
                 .Build();
 
             var response = await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);

Samples/Diagnostics/Logger_Samples.cs

@@ -8,6 +8,7 @@
 
 using System.Text;
 using MQTTnet.Diagnostics;
+using MQTTnet.Samples.Shared;
 
 namespace MQTTnet.Samples.Diagnostics;
 
@@ -22,9 +23,7 @@ public static class Logger_Samples
 
         var mqttFactory = new MqttFactory(new MyLogger());
 
-        var mqttClientOptions = mqttFactory.CreateClientOptionsBuilder()
+        var mqttClientOptions = mqttFactory.CreateClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
-            .WithTcpServer("broker.hivemq.com")
-            .Build();
 
         using (var mqttClient = mqttFactory.CreateMqttClient())
         {
@@ -32,13 +31,31 @@ public static class Logger_Samples
 
             Console.WriteLine("MQTT client is connected.");
 
-            var mqttClientDisconnectOptions = mqttFactory.CreateClientDisconnectOptionsBuilder()
+            var mqttClientDisconnectOptions = mqttFactory.CreateClientDisconnectOptionsBuilder().Build();
-                .Build();
 
             await mqttClient.DisconnectAsync(mqttClientDisconnectOptions, CancellationToken.None);
         }
     }
 
+    public static async Task Log_To_Console()
+    {
+        /*
+       * This sample covers the creation of a custom logger which is used to log to the console.
+       */
+
+        var mqttFactory = new MqttFactory(new ConsoleLogger());
+
+        var mqttClientOptions = mqttFactory.CreateClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
+
+        using (var mqttClient = mqttFactory.CreateMqttClient())
+        {
+            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+
+            Console.WriteLine("MQTT client is connected. Press any key to exit.");
+            Console.ReadKey(true);
+        }
+    }
+
     public static async Task Use_Event_Logger()
     {
         /*
@@ -64,9 +81,7 @@ public static class Logger_Samples
 
         var mqttFactory = new MqttFactory(mqttEventLogger);
 
-        var mqttClientOptions = mqttFactory.CreateClientOptionsBuilder()
+        var mqttClientOptions = mqttFactory.CreateClientOptionsBuilder().WithTcpServer("broker.hivemq.com").Build();
-            .WithTcpServer("broker.hivemq.com")
-            .Build();
 
         using (var mqttClient = mqttFactory.CreateMqttClient())
         {
@@ -74,8 +89,7 @@ public static class Logger_Samples
 
             Console.WriteLine("MQTT client is connected.");
 
-            var mqttClientDisconnectOptions = mqttFactory.CreateClientDisconnectOptionsBuilder()
+            var mqttClientDisconnectOptions = mqttFactory.CreateClientDisconnectOptionsBuilder().Build();
-                .Build();
 
             await mqttClient.DisconnectAsync(mqttClientDisconnectOptions, CancellationToken.None);
         }
@@ -83,7 +97,7 @@ public static class Logger_Samples
 
     sealed class MyLogger : IMqttNetLogger
     {
-        public bool IsEnabled { get; set; } = true;
+        public bool IsEnabled { get; } = true;
 
         public void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception)
         {

Samples/MQTTnet.Samples.csproj

@@ -9,10 +9,12 @@
         <DisableImplicitAspNetCoreAnalyzers>true</DisableImplicitAspNetCoreAnalyzers>
         <EnableNETAnalyzers>false</EnableNETAnalyzers>
         <EnforceCodeStyleInBuild>false</EnforceCodeStyleInBuild>
-        <NoWarn>1591;NETSDK1138</NoWarn>
+        <NoWarn>1591</NoWarn>
     </PropertyGroup>
 
     <ItemGroup>
+        <PackageReference Include="Microsoft.CodeAnalysis.Compilers" Version="4.0.1" />
+        <PackageReference Include="Microsoft.Net.Compilers" Version="4.0.1" />
 
         <ProjectReference Include="..\Source\MQTTnet.AspnetCore\MQTTnet.AspNetCore.csproj" />
         <ProjectReference Include="..\Source\MQTTnet.Extensions.ManagedClient\MQTTnet.Extensions.ManagedClient.csproj" />

Samples/Program.cs

@@ -8,6 +8,7 @@ Console.WriteLine("Welcome to MQTTnet samples!");
 Console.WriteLine();
 
 var sampleClasses = Assembly.GetExecutingAssembly().GetExportedTypes().OrderBy(c => c.Name).ToList();
+sampleClasses.RemoveAll(c => c.Namespace.Contains(".Shared"));
 
 var index = 0;
 foreach (var sampleClass in sampleClasses)

Samples/Server/Server_Intercepting_Samples.cs

@@ -1,47 +0,0 @@
-// 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
-// ReSharper disable EmptyConstructor
-// ReSharper disable MemberCanBeMadeStatic.Local
-
-using MQTTnet.Internal;
-using MQTTnet.Server;
-
-namespace MQTTnet.Samples.Server;
-
-public static class Server_Intercepting_Samples
-{
-    public static async Task Intercept_Application_Messages()
-    {
-        /*
-         * This sample starts a simple MQTT server which manipulate all processed application messages.
-         * Please see _Server_Simple_Samples_ for more details on how to start a server.
-         */
-
-        var mqttFactory = new MqttFactory();
-        var mqttServerOptions = new MqttServerOptionsBuilder().WithDefaultEndpoint().Build();
-
-        using (var mqttServer = mqttFactory.CreateMqttServer(mqttServerOptions))
-        {
-            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";
-
-                return CompletedTask.Instance;
-            };
-
-            await mqttServer.StartAsync();
-
-            Console.WriteLine("Press Enter to exit.");
-            Console.ReadLine();
-            await mqttServer.StopAsync();
-        }
-    }
-}

Samples/Server/Server_Simple_Samples.cs

@@ -6,8 +6,8 @@
 // ReSharper disable UnusedMember.Global
 // ReSharper disable InconsistentNaming
 
-using MQTTnet.Diagnostics;
 using MQTTnet.Protocol;
+using MQTTnet.Samples.Shared;
 using MQTTnet.Server;
 
 namespace MQTTnet.Samples.Server;
@@ -170,50 +170,4 @@ public static class Server_Simple_Samples
         await server.StartAsync();
         return server;
     }
-
-    class ConsoleLogger : IMqttNetLogger
-    {
-        readonly object _consoleSyncRoot = new();
-
-        public bool IsEnabled => true;
-
-        public void Publish(MqttNetLogLevel logLevel, string source, string message, object[]? parameters, Exception? exception)
-        {
-            var foregroundColor = ConsoleColor.White;
-            switch (logLevel)
-            {
-                case MqttNetLogLevel.Verbose:
-                    foregroundColor = ConsoleColor.White;
-                    break;
-
-                case MqttNetLogLevel.Info:
-                    foregroundColor = ConsoleColor.Green;
-                    break;
-
-                case MqttNetLogLevel.Warning:
-                    foregroundColor = ConsoleColor.DarkYellow;
-                    break;
-
-                case MqttNetLogLevel.Error:
-                    foregroundColor = ConsoleColor.Red;
-                    break;
-            }
-
-            if (parameters?.Length > 0)
-            {
-                message = string.Format(message, parameters);
-            }
-
-            lock (_consoleSyncRoot)
-            {
-                Console.ForegroundColor = foregroundColor;
-                Console.WriteLine(message);
-
-                if (exception != null)
-                {
-                    Console.WriteLine(exception);
-                }
-            }
-        }
-    }
 }

Samples/Shared/ConsoleLogger.cs

@@ -0,0 +1,53 @@
+// 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.
+
+using MQTTnet.Diagnostics;
+
+namespace MQTTnet.Samples.Shared;
+
+public sealed class ConsoleLogger : IMqttNetLogger
+{
+    readonly object _consoleSyncRoot = new();
+
+    public bool IsEnabled => true;
+
+    public void Publish(MqttNetLogLevel logLevel, string source, string message, object[]? parameters, Exception? exception)
+    {
+        var foregroundColor = ConsoleColor.White;
+        switch (logLevel)
+        {
+            case MqttNetLogLevel.Verbose:
+                foregroundColor = ConsoleColor.White;
+                break;
+
+            case MqttNetLogLevel.Info:
+                foregroundColor = ConsoleColor.Green;
+                break;
+
+            case MqttNetLogLevel.Warning:
+                foregroundColor = ConsoleColor.DarkYellow;
+                break;
+
+            case MqttNetLogLevel.Error:
+                foregroundColor = ConsoleColor.Red;
+                break;
+        }
+
+        if (parameters?.Length > 0)
+        {
+            message = string.Format(message, parameters);
+        }
+
+        lock (_consoleSyncRoot)
+        {
+            Console.ForegroundColor = foregroundColor;
+            Console.WriteLine(message);
+
+            if (exception != null)
+            {
+                Console.WriteLine(exception);
+            }
+        }
+    }
+}

Samples/Shared/ObjectExtensions.cs

@@ -4,7 +4,7 @@
 
 using System.Text.Json;
 
-namespace MQTTnet.Samples.Helpers;
+namespace MQTTnet.Samples.Shared;
 
 internal static class ObjectExtensions
 {

Source/MQTTnet.AspNetCore.Tests/MQTTnet.AspNetCore.Tests.csproj

@@ -12,6 +12,8 @@
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.2.0" />
         <PackageReference Include="MSTest.TestAdapter" Version="2.2.10" />
         <PackageReference Include="MSTest.TestFramework" Version="2.2.10" />
+        <PackageReference Include="Microsoft.CodeAnalysis.Compilers" Version="4.0.1" />
+        <PackageReference Include="Microsoft.Net.Compilers" Version="4.0.1" />
     </ItemGroup>
 
     <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp3.1' ">

Source/MQTTnet.AspNetCore.Tests/Mockups/ConnectionContextMockup.cs

@@ -0,0 +1,26 @@
+// 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.
+
+using System.Collections.Generic;
+using System.IO.Pipelines;
+using Microsoft.AspNetCore.Connections;
+using Microsoft.AspNetCore.Http.Features;
+
+namespace MQTTnet.AspNetCore.Tests.Mockups
+{
+    public class ConnectionContextMockup : ConnectionContext
+    {
+        public override string ConnectionId { get; set; }
+
+        public override IFeatureCollection Features { get; }
+
+        public override IDictionary<object, object> Items { get; set; }
+        public override IDuplexPipe Transport { get; set; }
+
+        public ConnectionContextMockup()
+        {
+            //Transport = new DefaultConnectionContext
+        }
+    }
+}

Source/MQTTnet.AspNetCore.Tests/Mockups/ConnectionHandlerMockup.cs

@@ -2,24 +2,20 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
-using System.Threading.Tasks;
 using Microsoft.AspNetCore.Connections;
 using MQTTnet.Adapter;
-using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
 using MQTTnet.Server;
+using System;
+using System.Threading.Tasks;
+using MQTTnet.Diagnostics;
 
 namespace MQTTnet.AspNetCore.Tests.Mockups
 {
-    public sealed class ConnectionHandlerMockup : IMqttServerAdapter
+    public class ConnectionHandlerMockup: IMqttServerAdapter
     {
-        public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
         public TaskCompletionSource<MqttConnectionContext> Context { get; } = new TaskCompletionSource<MqttConnectionContext>();
-
+        public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
-        public void Dispose()
-        {
-        }
 
         public async Task OnConnectedAsync(ConnectionContext connection)
         {
@@ -46,5 +42,9 @@ namespace MQTTnet.AspNetCore.Tests.Mockups
         {
             return Task.CompletedTask;
         }
+
+        public void Dispose()
+        {
+        }
     }
 }

Source/MQTTnet.AspNetCore.Tests/Mockups/DuplexPipeMockup.cs

@@ -6,7 +6,7 @@ using System.IO.Pipelines;
 
 namespace MQTTnet.AspNetCore.Tests.Mockups
 {
-    public sealed class DuplexPipeMockup : IDuplexPipe
+    public class DuplexPipeMockup : IDuplexPipe
     {
         public DuplexPipeMockup()
         {
@@ -20,8 +20,9 @@ namespace MQTTnet.AspNetCore.Tests.Mockups
 
         PipeWriter IDuplexPipe.Output => Send.Writer;
 
-        public Pipe Receive { get; } 
 
-        public Pipe Send { get; }
+        public Pipe Receive { get; set; } 
+
+        public Pipe Send { get; set; }
     }
 }

Source/MQTTnet.AspNetCore.Tests/Mockups/LimitedMemoryPool.cs

@@ -6,7 +6,7 @@ using System.Buffers;
 
 namespace MQTTnet.AspNetCore.Tests.Mockups
 {
-    public sealed class LimitedMemoryPool : MemoryPool<byte>
+    public class LimitedMemoryPool : MemoryPool<byte>
     {
         protected override void Dispose(bool disposing)
         {

Source/MQTTnet.AspNetCore.Tests/Mockups/MemoryOwner.cs

@@ -7,9 +7,9 @@ using System.Buffers;
 
 namespace MQTTnet.AspNetCore.Tests.Mockups
 {
-    public sealed class MemoryOwner : IMemoryOwner<byte>
+    public class MemoryOwner : IMemoryOwner<byte>
     {
-        readonly byte[] _raw;
+        private readonly byte[] _raw;
 
         public MemoryOwner(int size)
         {
@@ -27,11 +27,11 @@ namespace MQTTnet.AspNetCore.Tests.Mockups
             Memory = _raw;
         }
 
-        public Memory<byte> Memory { get; }
-
         public void Dispose()
         {
             ArrayPool<byte>.Shared.Return(_raw);
         }
+
+        public Memory<byte> Memory { get; }
     }
 }

Source/MQTTnet.AspNetCore.Tests/MqttConnectionContextTest.cs

@@ -2,29 +2,44 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
-using System.Net;
-using System.Threading;
-using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Connections;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+using System;
+using System.Net;
+using System.Threading;
+using System.Threading.Tasks;
 using MQTTnet.Adapter;
 using MQTTnet.AspNetCore.Tests.Mockups;
-using MQTTnet.Client;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
 using MQTTnet.Packets;
+using MQTTnet.Client;
 using MQTTnet.Protocol;
-using MQTTnet.Tests.Helpers;
+using MQTTnet.Tests.Extensions;
 
 namespace MQTTnet.AspNetCore.Tests
 {
     [TestClass]
     public class MqttConnectionContextTest
     {
+        [TestMethod]
+        public async Task TestReceivePacketAsyncThrowsWhenReaderCompleted()
+        {
+            var serializer = new MqttPacketFormatterAdapter(MqttProtocolVersion.V311, new MqttBufferWriter(4096, 65535));
+            var pipe = new DuplexPipeMockup();
+            var connection = new DefaultConnectionContext();
+            connection.Transport = pipe;
+            var ctx = new MqttConnectionContext(serializer, connection);
+
+            pipe.Receive.Writer.Complete();
+
+            await Assert.ThrowsExceptionAsync<MqttCommunicationException>(() => ctx.ReceivePacketAsync(CancellationToken.None));
+        }
+
         [TestMethod]
         public async Task TestCorruptedConnectPacket()
         {
@@ -35,42 +50,12 @@ namespace MQTTnet.AspNetCore.Tests
             connection.Transport = pipe;
             var ctx = new MqttConnectionContext(serializer, connection);
             
-            await pipe.Receive.Writer.WriteAsync(writer.AddMqttHeader(MqttControlPacketType.Connect, Array.Empty<byte>()));
+            await pipe.Receive.Writer.WriteAsync(writer.AddMqttHeader(MqttControlPacketType.Connect, new byte[0]));
 
             await Assert.ThrowsExceptionAsync<MqttProtocolViolationException>(() => ctx.ReceivePacketAsync(CancellationToken.None));
 
             // the first exception should complete the pipes so if someone tries to use the connection after that it should throw immidiatly
-            await Assert.ThrowsExceptionAsync<InvalidOperationException>(() => ctx.ReceivePacketAsync(CancellationToken.None));
+            await Assert.ThrowsExceptionAsync<InvalidOperationException>(() =>  ctx.ReceivePacketAsync(CancellationToken.None));
-        }
-
-        [TestMethod]
-        public async Task TestEndpoint()
-        {
-            var mockup = new ConnectionHandlerMockup();
-
-
-            using (var host = new WebHostBuilder().UseKestrel(kestrel => kestrel.ListenLocalhost(1883, listener => listener.Use((ctx, next) => mockup.OnConnectedAsync(ctx))))
-                       .UseStartup<Startup>()
-                       .ConfigureServices(
-                           (hostContext, services) =>
-                           {
-                               services.AddHostedMqttServer(o => o.WithoutDefaultEndpoint());
-                               services.AddSingleton<IMqttServerAdapter>(mockup);
-                           })
-                       .Build())
-
-            using (var client = new MqttFactory().CreateMqttClient())
-            {
-                host.Start();
-                await client.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("localhost").Build(), CancellationToken.None);
-
-                var ctx = await mockup.Context.Task;
-#if NETCOREAPP3_1
-                var ep = IPEndPoint.Parse(ctx.Endpoint);
-                Assert.IsNotNull(ep);
-#endif
-                Assert.IsNotNull(ctx);
-            }
         }
 
         // COMMENTED OUT DUE TO DEAD LOCK? OR VERY VERY SLOW PERFORMANCE ON LOCAL DEV MACHINE. TEST WAS STILL RUNNING AFTER SEVERAL MINUTES!
@@ -109,25 +94,43 @@ namespace MQTTnet.AspNetCore.Tests
             Assert.IsTrue(readResult.Buffer.Length > 20000);
         }
 
-        [TestMethod]
+        private class Startup 
-        public async Task TestReceivePacketAsyncThrowsWhenReaderCompleted()
-        {
-            var serializer = new MqttPacketFormatterAdapter(MqttProtocolVersion.V311, new MqttBufferWriter(4096, 65535));
-            var pipe = new DuplexPipeMockup();
-            var connection = new DefaultConnectionContext();
-            connection.Transport = pipe;
-            var ctx = new MqttConnectionContext(serializer, connection);
-
-            pipe.Receive.Writer.Complete();
-
-            await Assert.ThrowsExceptionAsync<MqttCommunicationException>(() => ctx.ReceivePacketAsync(CancellationToken.None));
-        }
-
-        class Startup
         {
             public void Configure(IApplicationBuilder app)
             { 
             }
         }
+
+        [TestMethod]
+        public async Task TestEndpoint()
+        {
+            var mockup = new ConnectionHandlerMockup();
+
+
+            using (var host = new WebHostBuilder()
+                .UseKestrel(kestrel => kestrel.ListenLocalhost(1883, listener => listener.Use((ctx, next) => mockup.OnConnectedAsync(ctx))))
+                .UseStartup<Startup>()
+                .ConfigureServices((hostContext, services) =>
+                {
+                    services.AddHostedMqttServer(o => o.WithoutDefaultEndpoint());
+                    services.AddSingleton<IMqttServerAdapter>(mockup);
+                })
+                .Build())
+                
+            using (var client = new MqttFactory().CreateMqttClient())
+            {
+                host.Start();
+                await client.ConnectAsync(new MqttClientOptionsBuilder()
+                    .WithTcpServer("localhost")
+                    .Build(), CancellationToken.None);
+
+                var ctx = await mockup.Context.Task;
+#if NETCOREAPP3_1
+                var ep = IPEndPoint.Parse(ctx.Endpoint);
+                Assert.IsNotNull(ep);
+#endif
+                Assert.IsNotNull(ctx);
+            }               
+        }
     }
 }

Source/MQTTnet.AspNetCore.Tests/ReaderExtensionsTest.cs

@@ -12,7 +12,7 @@ using MQTTnet.Packets;
 namespace MQTTnet.AspNetCore.Tests
 {
     [TestClass]
-    public sealed class ReaderExtensionsTest
+    public class ReaderExtensionsTest
     {
         [TestMethod]
         public void TestTryDeserialize()

Source/MQTTnet.AspTestApp/MQTTnet.AspTestApp.csproj

@@ -8,15 +8,17 @@
         <DisableImplicitAspNetCoreAnalyzers>true</DisableImplicitAspNetCoreAnalyzers>
         <EnableNETAnalyzers>false</EnableNETAnalyzers>
         <EnforceCodeStyleInBuild>false</EnforceCodeStyleInBuild>
-        <NoWarn>1591;NETSDK1138</NoWarn>
     </PropertyGroup>
 
     <ItemGroup>
-        <ProjectReference Include="..\..\Source\MQTTnet.AspnetCore\MQTTnet.AspNetCore.csproj" />
+        <ProjectReference Include="..\..\Source\MQTTnet.AspnetCore\MQTTnet.AspNetCore.csproj"/>
+
+        <PackageReference Include="Microsoft.CodeAnalysis.Compilers" Version="4.0.1" />
+        <PackageReference Include="Microsoft.Net.Compilers" Version="4.0.1" />
     </ItemGroup>
 
     <ItemGroup>
-        <Folder Include="wwwroot\" />
+        <Folder Include="wwwroot\"/>
     </ItemGroup>
 
 </Project>

Source/MQTTnet.AspnetCore/MQTTnet.AspNetCore.csproj

@@ -32,8 +32,7 @@
         <DisableImplicitAspNetCoreAnalyzers>true</DisableImplicitAspNetCoreAnalyzers>
         <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
         <GenerateDocumentationFile>true</GenerateDocumentationFile>
-        <NoWarn>1591;NETSDK1138</NoWarn>
+        <NoWarn>1591</NoWarn>
-        <LangVersion>7.3</LangVersion>
     </PropertyGroup>
 
     <ItemGroup>

Source/MQTTnet.AspnetCore/MqttConnectionContext.cs

@@ -2,27 +2,24 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
-using System.IO.Pipelines;
-using System.Net;
-using System.Security.Cryptography.X509Certificates;
-using System.Threading;
-using System.Threading.Tasks;
 using Microsoft.AspNetCore.Connections;
 using Microsoft.AspNetCore.Http.Connections.Features;
-using Microsoft.AspNetCore.Http.Features;
 using MQTTnet.Adapter;
 using MQTTnet.AspNetCore.Client.Tcp;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
-using MQTTnet.Internal;
 using MQTTnet.Packets;
+using System;
+using System.IO.Pipelines;
+using System.Security.Cryptography.X509Certificates;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Internal;
 
 namespace MQTTnet.AspNetCore
 {
     public sealed class MqttConnectionContext : IMqttChannelAdapter
     {
-        readonly ConnectionContext _connection;
         readonly AsyncLock _writerLock = new AsyncLock();
         
         PipeReader _input;
@@ -31,30 +28,12 @@ namespace MQTTnet.AspNetCore
         public MqttConnectionContext(MqttPacketFormatterAdapter packetFormatterAdapter, ConnectionContext connection)
         {
             PacketFormatterAdapter = packetFormatterAdapter ?? throw new ArgumentNullException(nameof(packetFormatterAdapter));
-            _connection = connection ?? throw new ArgumentNullException(nameof(connection));
+            Connection = connection ?? throw new ArgumentNullException(nameof(connection));
 
-            _input = connection.Transport.Input;
+            if (Connection.Transport != null)
-            _output = connection.Transport.Output;
-        }
-
-        public long BytesReceived { get; private set; }
-
-        public long BytesSent { get; private set; }
-
-        public X509Certificate2 ClientCertificate
-        {
-            get
             {
-                // mqtt over tcp
+                _input = Connection.Transport.Input;
-                var tlsFeature = _connection.Features.Get<ITlsConnectionFeature>();
+                _output = Connection.Transport.Output;
-                if (tlsFeature != null)
-                {
-                    return tlsFeature.ClientCertificate;
-                }
-
-                // mqtt over websocket
-                var httpFeature = _connection.Features.Get<IHttpContextFeature>();
-                return httpFeature?.HttpContext?.Connection.ClientCertificate;
             }
         }
 
@@ -62,59 +41,47 @@ namespace MQTTnet.AspNetCore
         {
             get
             {
-                // mqtt over tcp 
+#if NETCOREAPP3_1
-#if NETCOREAPP3_1_OR_GREATER
+                if (Connection?.RemoteEndPoint != null)
-                if (_connection.RemoteEndPoint != null)
                 {
-                    return _connection.RemoteEndPoint.ToString();
+                    return Connection.RemoteEndPoint.ToString();
                 }
 #endif
-                // mqtt over websocket
+                var connection = Http?.HttpContext?.Connection;
-                var httpFeature = _connection.Features.Get<IHttpConnectionFeature>();
+                if (connection == null)
-                if (httpFeature?.RemoteIpAddress != null)
                 {
-                    return new IPEndPoint(httpFeature.RemoteIpAddress, httpFeature.RemotePort).ToString();
+                    return Connection.ConnectionId;
                 }
 
-                return null;
+                return $"{connection.RemoteIpAddress}:{connection.RemotePort}";
             }
         }
 
-        public bool IsReadingPacket { get; private set; }
+        public bool IsSecureConnection => Http?.HttpContext?.Request?.IsHttps ?? false;
 
-        public bool IsSecureConnection
+        public X509Certificate2 ClientCertificate => Http?.HttpContext?.Connection?.ClientCertificate;
-        {
-            get
-            {
-                // mqtt over tcp
-                var tlsFeature = _connection.Features.Get<ITlsConnectionFeature>();
-                if (tlsFeature != null)
-                {
-                    return true;
-                }
 
-                // mqtt over websocket
+        public ConnectionContext Connection { get; }
-                var httpFeature = _connection.Features.Get<IHttpContextFeature>();
-                if (httpFeature?.HttpContext != null)
-                {
-                    return httpFeature.HttpContext.Request.IsHttps;
-                }
-
-                return false;
-            }
-        }
         
         public MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
 
+        public long BytesSent { get; set; }
+
+        public long BytesReceived { get; set; }
+
+        public bool IsReadingPacket { get; private set; }
+
+        IHttpContextFeature Http => Connection.Features.Get<IHttpContextFeature>();
+
         public async Task ConnectAsync(CancellationToken cancellationToken)
         {
-            if (_connection is TcpConnection tcp && !tcp.IsConnected)
+            if (Connection is TcpConnection tcp && !tcp.IsConnected)
             {
                 await tcp.StartAsync().ConfigureAwait(false);
             }
 
-            _input = _connection.Transport.Input;
+            _input = Connection.Transport.Input;
-            _output = _connection.Transport.Output;
+            _output = Connection.Transport.Output;
         }
 
         public Task DisconnectAsync(CancellationToken cancellationToken)
@@ -125,19 +92,16 @@ namespace MQTTnet.AspNetCore
             return Task.CompletedTask;
         }
 
-        public void Dispose()
-        {
-            _writerLock.Dispose();
-        }
-
         public async Task<MqttPacket> ReceivePacketAsync(CancellationToken cancellationToken)
         {
+            var input = Connection.Transport.Input;
+
             try
             {
                 while (!cancellationToken.IsCancellationRequested)
                 {
                     ReadResult readResult;
-                    var readTask = _input.ReadAsync(cancellationToken);
+                    var readTask = input.ReadAsync(cancellationToken);
                     if (readTask.IsCompleted)
                     {
                         readResult = readTask.Result;
@@ -177,15 +141,15 @@ namespace MQTTnet.AspNetCore
                         // The buffer was sliced up to where it was consumed, so we can just advance to the start.
                         // We mark examined as buffer.End so that if we didn't receive a full frame, we'll wait for more data
                         // before yielding the read again.
-                        _input.AdvanceTo(consumed, observed);
+                        input.AdvanceTo(consumed, observed);
                     }
                 }
             }
-            catch (Exception exception)
+            catch (Exception e)
             {
                 // completing the channel makes sure that there is no more data read after a protocol error
-                _input?.Complete(exception);
+                _input?.Complete(e);
-                _output?.Complete(exception);
+                _output?.Complete(e);
                 throw;
             }
             finally
@@ -205,35 +169,25 @@ namespace MQTTnet.AspNetCore
 
         public async Task SendPacketAsync(MqttPacket packet, CancellationToken cancellationToken)
         {
-            using (await _writerLock.EnterAsync(cancellationToken).ConfigureAwait(false))
+            var formatter = PacketFormatterAdapter;
+            
+            using (await _writerLock.WaitAsync(cancellationToken).ConfigureAwait(false))
             {
-                try
+                var buffer = formatter.Encode(packet);
+                var msg = buffer.Join().AsMemory();
+                var output = _output;
+                var result = await output.WriteAsync(msg, cancellationToken).ConfigureAwait(false);
+                if (result.IsCompleted)
                 {
-                    var buffer = PacketFormatterAdapter.Encode(packet);
+                    BytesSent += msg.Length;
-
-                    WritePacketBuffer(_output, buffer);
-                    await _output.FlushAsync(cancellationToken).ConfigureAwait(false);
-
-                    BytesSent += buffer.Length;
-                }
-                finally
-                {
-                    PacketFormatterAdapter.Cleanup();
                 }
+
+                PacketFormatterAdapter.Cleanup();
             }
         }
 
-        static void WritePacketBuffer(PipeWriter output, MqttPacketBuffer buffer)
+        public void Dispose()
         {
-            // copy MqttPacketBuffer's Packet and Payload to the same buffer block of PipeWriter
-            // MqttPacket will be transmitted within the bounds of a WebSocket frame after PipeWriter.FlushAsync
-
-            var span = output.GetSpan(buffer.Length);
-
-            buffer.Packet.AsSpan().CopyTo(span);
-            buffer.Payload.AsSpan().CopyTo(span.Slice(buffer.Packet.Count));
-
-            output.Advance(buffer.Length);
         }
     }
 }

Source/MQTTnet.AspnetCore/ReaderExtensions.cs

@@ -2,14 +2,12 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
+using System.Buffers;
 using MQTTnet.Adapter;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
 using MQTTnet.Packets;
-using System;
-using System.Buffers;
-using System.Linq;
-using System.Runtime.InteropServices;
 
 namespace MQTTnet.AspNetCore
 {
@@ -35,22 +33,22 @@ namespace MQTTnet.AspNetCore
                 return false;
             }
 
-            if (!TryReadBodyLength(ref copy, out var headerLength, out var bodyLength))
+            var fixedHeader = copy.First.Span[0];
+            if (!TryReadBodyLength(ref copy, out int headerLength, out var bodyLength))
             {
                 return false;
             }
 
-            var fixedHeader = copy.First.Span[0];
-            copy = copy.Slice(headerLength);
             if (copy.Length < bodyLength)
             {
                 return false;
             }
 
             var bodySlice = copy.Slice(0, bodyLength);
-            var bodySegment = GetArraySegment(ref bodySlice); 
+            var buffer = bodySlice.GetMemory().ToArray();
+            
+            var receivedMqttPacket = new ReceivedMqttPacket(fixedHeader, new ArraySegment<byte>(buffer, 0, buffer.Length), buffer.Length + 2);
 
-            var receivedMqttPacket = new ReceivedMqttPacket(fixedHeader, bodySegment, headerLength + bodyLength);
             if (formatter.ProtocolVersion == MqttProtocolVersion.Unknown)
             {
                 formatter.DetectProtocolVersion(receivedMqttPacket);
@@ -63,41 +61,18 @@ namespace MQTTnet.AspNetCore
             return true;
         }
 
-        static ArraySegment<byte> GetArraySegment(ref ReadOnlySequence<byte> input)
+        static ReadOnlyMemory<byte> GetMemory(this in ReadOnlySequence<byte> input)
         {
-            if (input.IsSingleSegment && MemoryMarshal.TryGetArray(input.First, out var segment))
+            if (input.IsSingleSegment)
             {
-                return segment;
+                return input.First;
             }
 
             // Should be rare
-            var array = input.ToArray();
+            return input.ToArray();
-            return new ArraySegment<byte>(array);
         }
 
         static bool TryReadBodyLength(ref ReadOnlySequence<byte> input, out int headerLength, out int bodyLength)
-        {
-            var valueSequence = input.Slice(0, Math.Min(5, input.Length));
-            if (valueSequence.IsSingleSegment)
-            {
-                var valueSpan =
-#if NET5_0_OR_GREATER
-                    valueSequence.FirstSpan;
-#else
-                    valueSequence.First.Span;
-#endif
-                return TryReadBodyLength(valueSpan, out headerLength, out bodyLength);
-            }
-            else
-            {
-                Span<byte> valueSpan = stackalloc byte[8];
-                valueSequence.CopyTo(valueSpan);
-                valueSpan = valueSpan.Slice(0, (int)valueSequence.Length);
-                return TryReadBodyLength(valueSpan, out headerLength, out bodyLength);
-            }
-        }
-
-        static bool TryReadBodyLength(ReadOnlySpan<byte> span, out int headerLength, out int bodyLength)
         {
             // Alorithm taken from https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/errata01/os/mqtt-v3.1.1-errata01-os-complete.html.
             var multiplier = 1;
@@ -107,34 +82,32 @@ namespace MQTTnet.AspNetCore
             headerLength = 0;
             bodyLength = 0;
             
+            var temp = input.Slice(0, Math.Min(5, input.Length)).GetMemory().Span;
+
             do
             {
-                if (index == span.Length)
+                if (index == temp.Length)
                 {
                     return false;
                 }
 
-                encodedByte = span[index];
+                encodedByte = temp[index];
                 index++;
 
                 value += (byte)(encodedByte & 127) * multiplier;
                 if (multiplier > 128 * 128 * 128)
                 {
-                    ThrowProtocolViolationException(span, index);
+                    throw new MqttProtocolViolationException($"Remaining length is invalid (Data={string.Join(",", temp.Slice(1, index).ToArray())}).");
                 }
 
                 multiplier *= 128;
             } while ((encodedByte & 128) != 0);
 
+            input = input.Slice(index);
+
             headerLength = index;
             bodyLength = value;
             return true;
         }
-
-
-        static void ThrowProtocolViolationException(ReadOnlySpan<byte> valueSpan, int index)
-        {
-            throw new MqttProtocolViolationException($"Remaining length is invalid (Data={string.Join(",", valueSpan.Slice(1, index).ToArray())}).");
-        }
     }
 }

Source/MQTTnet.Benchmarks/AsyncLockBenchmark.cs

@@ -1,66 +0,0 @@
-// 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.
-
-using System;
-using System.Threading;
-using System.Threading.Tasks;
-using BenchmarkDotNet.Attributes;
-using BenchmarkDotNet.Jobs;
-using MQTTnet.Internal;
-
-namespace MQTTnet.Benchmarks
-{
-    [SimpleJob(RuntimeMoniker.Net60)]
-    [MemoryDiagnoser]
-    public class AsyncLockBenchmark : BaseBenchmark
-    {
-        [Benchmark]
-        public async Task Synchronize_100_Tasks()
-        {
-            const int tasksCount = 100;
-
-            var tasks = new Task[tasksCount];
-            var asyncLock = new AsyncLock();
-            var globalI = 0;
-
-            for (var i = 0; i < tasksCount; i++)
-            {
-                tasks[i] = Task.Run(
-                    async () =>
-                    {
-                        using (await asyncLock.EnterAsync().ConfigureAwait(false))
-                        {
-                            var localI = globalI;
-                            await Task.Delay(5).ConfigureAwait(false); // Increase the chance for wrong data.
-                            localI++;
-                            globalI = localI;
-                        }
-                    });
-            }
-
-            await Task.WhenAll(tasks).ConfigureAwait(false);
-
-            if (globalI != tasksCount)
-            {
-                throw new Exception($"Code is broken ({globalI})!");
-            }
-        }
-        
-        [Benchmark]
-        public async Task Wait_100_000_Times()
-        {
-            var asyncLock = new AsyncLock();
-
-            using (var cancellationToken = new CancellationTokenSource())
-            {
-                for (var i = 0; i < 100000; i++)
-                {
-                    using (await asyncLock.EnterAsync(cancellationToken.Token).ConfigureAwait(false))
-                    {
-                    }
-                }
-            }
-        }
-    }
-}

Source/MQTTnet.Benchmarks/BaseBenchmark.cs

@@ -1,7 +1,3 @@
-// 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.
-
 namespace MQTTnet.Benchmarks
 {
     public abstract class BaseBenchmark

Source/MQTTnet.Benchmarks/ChannelAdapterBenchmark.cs

@@ -2,51 +2,26 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using BenchmarkDotNet.Attributes;
+using MQTTnet.Adapter;
+using MQTTnet.Internal;
+using MQTTnet.Packets;
 using System;
 using System.IO;
 using System.Threading;
-using BenchmarkDotNet.Attributes;
-using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
-using MQTTnet.Packets;
 using MQTTnet.Tests.Mockups;
 
 namespace MQTTnet.Benchmarks
 {
     [MemoryDiagnoser]
-    public sealed class ChannelAdapterBenchmark : BaseBenchmark
+    public sealed class ChannelAdapterBenchmark
     {
         MqttChannelAdapter _channelAdapter;
         int _iterations;
-        MqttPublishPacket _packet;
         MemoryStream _stream;
-
+        MqttPublishPacket _packet;
-        [Benchmark]
-        public void Receive_10000_Messages()
-        {
-            _stream.Position = 0;
-
-            for (var i = 0; i < 10000; i++)
-            {
-                _channelAdapter.ReceivePacketAsync(CancellationToken.None).GetAwaiter().GetResult();
-            }
-
-            _stream.Position = 0;
-        }
-
-        [Benchmark]
-        public void Send_10000_Messages()
-        {
-            _stream.Position = 0;
-
-            for (var i = 0; i < 10000; i++)
-            {
-                _channelAdapter.SendPacketAsync(_packet, CancellationToken.None).GetAwaiter().GetResult();
-            }
-
-            _stream.Position = 0;
-        }
 
         [GlobalSetup]
         public void Setup()
@@ -76,6 +51,32 @@ namespace MQTTnet.Benchmarks
             _channelAdapter = new MqttChannelAdapter(channel, serializer, null, new MqttNetEventLogger());
         }
 
+        [Benchmark]
+        public void Receive_10000_Messages()
+        {
+            _stream.Position = 0;
+
+            for (var i = 0; i < 10000; i++)
+            {
+                _channelAdapter.ReceivePacketAsync(CancellationToken.None).GetAwaiter().GetResult();
+            }
+
+            _stream.Position = 0;
+        }
+
+        [Benchmark]
+        public void Send_10000_Messages()
+        {
+            _stream.Position = 0;
+
+            for (var i = 0; i < 10000; i++)
+            {
+                _channelAdapter.SendPacketAsync(_packet, CancellationToken.None).GetAwaiter().GetResult();
+            }
+
+            _stream.Position = 0;
+        }
+
         static byte[] Join(params ArraySegment<byte>[] chunks)
         {
             var buffer = new MemoryStream();

Source/MQTTnet.Benchmarks/Configurations/AllowNonOptimized.cs

@@ -0,0 +1,22 @@
+// 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.
+
+using BenchmarkDotNet.Jobs;
+using BenchmarkDotNet.Validators;
+
+namespace MQTTnet.Benchmarks.Configurations
+{
+    /// <summary>
+    /// this options may be used to run benchmarks in debugmode and attach a performance profiler
+    /// https://benchmarkdotnet.org/Configs/Configs.htm
+    /// </summary>
+    public class AllowNonOptimized : BaseConfig
+    {
+        public AllowNonOptimized()
+        {
+            AddValidator(JitOptimizationsValidator.DontFailOnError); // ALLOW NON-OPTIMIZED DLLS
+            AddJob(Job.InProcess);
+        }
+    }
+}

Source/MQTTnet.Benchmarks/Configurations/BaseConfig.cs

@@ -0,0 +1,19 @@
+// 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.
+
+using BenchmarkDotNet.Configs;
+using System.Linq;
+
+namespace MQTTnet.Benchmarks.Configurations
+{
+    public class BaseConfig : ManualConfig
+    {
+        public BaseConfig()
+        {
+            AddLogger(DefaultConfig.Instance.GetLoggers().ToArray()); // manual config has no loggers by default
+            AddExporter(DefaultConfig.Instance.GetExporters().ToArray()); // manual config has no exporters by default
+            AddColumnProvider(DefaultConfig.Instance.GetColumnProviders().ToArray()); // manual config has no columns by default
+        }
+    }
+}

Source/MQTTnet.Benchmarks/Configurations/RuntimeCompareConfig.cs

@@ -0,0 +1,19 @@
+// 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.
+
+using BenchmarkDotNet.Environments;
+using BenchmarkDotNet.Jobs;
+using BenchmarkDotNet.Toolchains.CsProj;
+
+namespace MQTTnet.Benchmarks.Configurations
+{
+    public class RuntimeCompareConfig : BaseConfig
+    {
+        public RuntimeCompareConfig()
+        {
+            AddJob(Job.Default.WithRuntime(ClrRuntime.Net48));
+            AddJob(Job.Default.WithRuntime(CoreRuntime.Core50).WithToolchain(CsProjCoreToolchain.NetCoreApp50));
+        }
+    }
+}

Source/MQTTnet.Benchmarks/LoggerBenchmark.cs

@@ -11,7 +11,7 @@ namespace MQTTnet.Benchmarks
     [SimpleJob(RuntimeMoniker.Net60)]
     [RPlotExporter]
     [MemoryDiagnoser]
-    public class LoggerBenchmark : BaseBenchmark
+    public class LoggerBenchmark
     {
         MqttNetNullLogger _nullLogger;
         MqttNetSourceLogger _sourceNullLogger;

Source/MQTTnet.Benchmarks/MQTTnet.Benchmarks.csproj

@@ -1,23 +1,25 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
         <OutputType>Exe</OutputType>
         <DebugType>Full</DebugType>
-        <TargetFrameworks>net6.0</TargetFrameworks>
+        <TargetFrameworks>net5.0;net6.0</TargetFrameworks>
         <LangVersion>7.2</LangVersion>
         <IsPackable>false</IsPackable>
         <EnableNETAnalyzers>false</EnableNETAnalyzers>
         <EnforceCodeStyleInBuild>false</EnforceCodeStyleInBuild>
         <DisableImplicitAspNetCoreAnalyzers>true</DisableImplicitAspNetCoreAnalyzers>
-        <NoWarn>1591;NETSDK1138</NoWarn>
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="BenchmarkDotNet" Version="0.13.2" />
+        <PackageReference Include="BenchmarkDotNet" Version="0.13.1" />
         <PackageReference Include="Microsoft.AspNetCore" Version="2.2.0" />
     </ItemGroup>
 
+    <ItemGroup Condition="'$(TargetFramework)' != 'net5.0'">
+        <PackageReference Include="System.IO.Pipelines" Version="4.7.2" />
+    </ItemGroup>
+
     <ItemGroup Condition="'$(TargetFramework)' == 'net5.0'">
         <PackageReference Include="System.IO.Pipelines" Version="5.0.0" />
     </ItemGroup>
@@ -28,6 +30,9 @@
 
     <ItemGroup>
         <ProjectReference Include="..\..\Source\MQTTnet.AspnetCore\MQTTnet.AspNetCore.csproj" />
+
+        <PackageReference Include="Microsoft.CodeAnalysis.Compilers" Version="4.0.1" />
+        <PackageReference Include="Microsoft.Net.Compilers" Version="4.0.1" />
         <ProjectReference Include="..\MQTTnet.Tests\MQTTnet.Tests.csproj" />
     </ItemGroup>
 

Source/MQTTnet.Benchmarks/MemoryCopyBenchmark.cs

@@ -1,40 +0,0 @@
-using BenchmarkDotNet.Attributes;
-using BenchmarkDotNet.Jobs;
-using System;
-
-
-namespace MQTTnet.Benchmarks
-{
-    [SimpleJob(RuntimeMoniker.Net60)]
-    [RPlotExporter, RankColumn]
-    [MemoryDiagnoser]
-    public class MemoryCopyBenchmark
-    {
-        const int max_length = 1024 * 8;
-        private byte[] source;
-        private byte[] target;
-
-        [Params(64 - 1, 128 - 1, 256 - 1, 512 - 1, 1024 - 1, 2048 - 1, 5096 - 1)]
-        public int Length { get; set; }
-
-        [GlobalSetup]
-        public void Setup()
-        {
-            source = new byte[max_length];
-            target = new byte[max_length];
-        }
-
-        [Benchmark(Baseline = true)]
-        public void Array_Copy()
-        {
-            Array.Copy(source, 0, target, 0, Length);
-        }
-
-        [Benchmark]
-        public void Memory_Copy()
-        {
-            MQTTnet.Internal.MqttMemoryHelper.Copy(source, 0, target, 0, Length);
-        }
-
-    }
-}

Source/MQTTnet.Benchmarks/MessageDeliveryBenchmark.cs

@@ -1,8 +1,5 @@
-// 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.
-
 using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Jobs;
 using MQTTnet.Client;
 using MQTTnet.Server;
 using System;
@@ -11,10 +8,14 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 
+
 namespace MQTTnet.Benchmarks
 {
+    /// <summary>
+    /// Create a number of topics, publish, subscribe, and wait for response
+    /// </summary>
     [MemoryDiagnoser]
-    public class MessageDeliveryBenchmark : BaseBenchmark
+    public class MessageDeliveryBenchmark
     {
         List<MqttApplicationMessage> _topicPublishMessages;
 

Source/MQTTnet.Benchmarks/MessageProcessingBenchmark.cs

@@ -12,7 +12,7 @@ namespace MQTTnet.Benchmarks
     [SimpleJob(RuntimeMoniker.Net60)]
     [RPlotExporter, RankColumn]
     [MemoryDiagnoser]
-    public class MessageProcessingBenchmark : BaseBenchmark
+    public class MessageProcessingBenchmark
     {
         MqttServer _mqttServer;
         IMqttClient _mqttClient;

Source/MQTTnet.Benchmarks/MessageProcessingMqttConnectionContextBenchmark.cs

@@ -15,7 +15,7 @@ namespace MQTTnet.Benchmarks
 {
     [SimpleJob(RuntimeMoniker.Net60)]
     [MemoryDiagnoser]
-    public class MessageProcessingMqttConnectionContextBenchmark : BaseBenchmark
+    public class MessageProcessingMqttConnectionContextBenchmark
     {
         IWebHost _host;
         IMqttClient _mqttClient;

Source/MQTTnet.Benchmarks/MqttBufferReaderBenchmark.cs

@@ -1,43 +0,0 @@
-// 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.
-
-using System;
-using System.Text;
-using BenchmarkDotNet.Attributes;
-using BenchmarkDotNet.Jobs;
-using MQTTnet.Formatter;
-
-namespace MQTTnet.Benchmarks
-{
-    [SimpleJob(RuntimeMoniker.Net60)]
-    [MemoryDiagnoser]
-    public class MqttBufferReaderBenchmark
-    {
-        byte[] _buffer;
-        int _bufferLength;
-
-        [GlobalSetup]
-        public void GlobalSetup()
-        {
-            var writer = new MqttBufferWriter(1024, 1024);
-            writer.WriteString("hgfjkdfkjlghfdjghdfljkdfhgdlkjfshgsldkfjghsdflkjghdsflkjhrstiuoghlkfjbhnfbutghjoiöjhklötnbhtroliöuhbjntluiobkjzbhtdrlskbhtruhjkfthgbkftgjhgfiklhotriuöhbjtrsioöbtrsötrhträhtrühjtriüoätrhjtsrölbktrbnhtrulöbionhströloubinströoliubhnsöotrunbtöroisntröointröioujhgötiohjgötorshjnbgtöorihbnjtröoihbjntröobntröoibntrjhötrohjbtröoihntröoibnrtoiöbtrjnboöitrhjtnriohötrhjtöroihjtroöihjtroösibntsroönbotöirsbntöoihjntröoihntroöbtrboöitrnhoöitrhjntröoishbnjtröosbhtröbntriohjtröoijtöoitbjöotibjnhöotirhbjntroöibhnjrtoöibnhtroöibnhtörsbnhtöoirbnhtöroibntoörhjnbträöbtrbträbtrbtirbätrsibohjntrsöiobthnjiohjsrtoib");
-
-            _buffer = writer.GetBuffer();
-            _bufferLength = writer.Length;
-        }
-
-        [Benchmark]
-        public void Use_Span()
-        {
-            var span = _buffer.AsSpan(0, _bufferLength);
-            Encoding.UTF8.GetString(span);
-        }
-        
-        [Benchmark]
-        public void Use_Encoding()
-        {
-            Encoding.UTF8.GetString(_buffer, 0, _bufferLength);
-        }
-    }
-}

Source/MQTTnet.Benchmarks/MqttPacketReaderWriterBenchmark.cs

@@ -1,10 +1,7 @@
-// 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.
-
 using System;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
+using MQTTnet.AspNetCore;
 using MQTTnet.Formatter;
 using MQTTnet.Tests.Mockups;
 
@@ -12,7 +9,7 @@ namespace MQTTnet.Benchmarks
 {
     [SimpleJob(RuntimeMoniker.Net60)]
     [MemoryDiagnoser]
-    public class MqttPacketReaderWriterBenchmark : BaseBenchmark
+    public class MqttPacketReaderWriterBenchmark
     {
         readonly byte[] _demoPayload = new byte[1024];
         

Source/MQTTnet.Benchmarks/MqttTcpChannelBenchmark.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using BenchmarkDotNet.Attributes;
 using MQTTnet.Channel;
 using MQTTnet.Implementations;
@@ -17,7 +16,7 @@ namespace MQTTnet.Benchmarks
 {
     [SimpleJob(RuntimeMoniker.Net60)]
     [MemoryDiagnoser]
-    public class MqttTcpChannelBenchmark : BaseBenchmark
+    public sealed class MqttTcpChannelBenchmark
     {
         MqttServer _mqttServer;
         IMqttChannel _serverChannel;
@@ -71,8 +70,8 @@ namespace MQTTnet.Benchmarks
 
             while (read < expected)
             {
-                var readResult = await _clientChannel.ReadAsync(new byte[size], 0, size, CancellationToken.None).ConfigureAwait(false);
+                var readresult = await _clientChannel.ReadAsync(new byte[size], 0, size, CancellationToken.None).ConfigureAwait(false);
-                read += readResult;
+                read += readresult;
             }
         }
 
@@ -80,11 +79,9 @@ namespace MQTTnet.Benchmarks
         {
             await Task.Yield();
 
-            var buffer = new ArraySegment<byte>(new byte[size]);
-            
             for (var i = 0; i < iterations; i++)
             {
-                await _serverChannel.WriteAsync(buffer, true, CancellationToken.None).ConfigureAwait(false);
+                await _serverChannel.WriteAsync(new byte[size], 0, size, CancellationToken.None).ConfigureAwait(false);
             }
         }
     }

Source/MQTTnet.Benchmarks/Program.cs

@@ -3,140 +3,81 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.Collections.Generic;
-using System.Linq;
-using BenchmarkDotNet.Loggers;
 using BenchmarkDotNet.Running;
+using MQTTnet.Benchmarks.Configurations;
 using MQTTnet.Diagnostics;
 
 namespace MQTTnet.Benchmarks
 {
     public static class Program
     {
-        static int _selectedBenchmarkIndex;
+        public static void Main(string[] args)
-        static List<Type> _benchmarks;
-
-        public static void Main(string[] arguments)
         {
-            _benchmarks = CollectBenchmarks();
-            HandleArguments(arguments);
-
-            while (true)
-            {
-                RenderMenu();
-
-                var key = Console.ReadKey(true);
-
-                if (key.Key == ConsoleKey.DownArrow)
-                {
-                    _selectedBenchmarkIndex++;
-                    if (_selectedBenchmarkIndex > _benchmarks.Count - 1)
-                    {
-                        _selectedBenchmarkIndex = 0;
-                    }
-                }
-                else if (key.Key == ConsoleKey.UpArrow)
-                {
-                    _selectedBenchmarkIndex--;
-                    if (_selectedBenchmarkIndex < 0)
-                    {
-                        _selectedBenchmarkIndex = _benchmarks.Count - 1;
-                    }
-                }
-                else if (key.Key == ConsoleKey.Escape)
-                {
-                    Environment.Exit(0);
-                }
-                else if (key.Key == ConsoleKey.Enter)
-                {
-                    break;
-                }
-            }
-
-            BenchmarkRunner.Run(_benchmarks[_selectedBenchmarkIndex]);
-
-            Console.ForegroundColor = ConsoleColor.Yellow;
-            Console.WriteLine("Press any key to exit");
-            Console.ReadLine();
-        }
-
-        static List<Type> CollectBenchmarks()
-        {
-            var benchmarks = new List<Type>();
-
-            var types = typeof(Program).Assembly.GetExportedTypes();
-            foreach (var type in types)
-            {
-                if (typeof(BaseBenchmark).IsAssignableFrom(type))
-                {
-                    if (type != typeof(BaseBenchmark))
-                    {
-                        benchmarks.Add(type);        
-                    }
-                }
-            }
-
-            return benchmarks.OrderBy(b => b.Name).ToList();
-        }
-
-        static void HandleArguments(string[] arguments)
-        {
-            if (arguments.Length == 0)
-            {
-                return;
-            }
-
-            // Allow for preselection to avoid developer frustration.
-            
-            if (int.TryParse(arguments[0], out var benchmarkIndex))
-            {
-                _selectedBenchmarkIndex = benchmarkIndex;
-                return;
-            }
-
-            _selectedBenchmarkIndex = _benchmarks.FindIndex(b => b.Name.Equals(arguments[0]));
-
-            if (_selectedBenchmarkIndex < 0)
-            {
-                _selectedBenchmarkIndex = 0;
-            }
-
-            if (_selectedBenchmarkIndex > _benchmarks.Count - 1)
-            {
-                _selectedBenchmarkIndex = _benchmarks.Count - 1;
-            }
-        }
-
-        static void RenderMenu()
-        {
-            Console.Clear();
-
             Console.WriteLine($"MQTTnet - Benchmarks ({TargetFrameworkProvider.TargetFramework})");
-            Console.WriteLine("-----------------------------------------------");
+            Console.WriteLine("--------------------------------------------------------");
-            Console.ForegroundColor = ConsoleColor.Yellow;
+            Console.WriteLine("1 = MessageProcessingBenchmark");
-            Console.WriteLine("Press arrow keys for benchmark selection");
+            Console.WriteLine("2 = SerializerBenchmark");
-            Console.WriteLine("Press Enter for benchmark execution");
+            Console.WriteLine("3 = LoggerBenchmark");
-            Console.WriteLine("Press Esc for exit");
+            Console.WriteLine("4 = TopicFilterComparerBenchmark");
-            Console.ForegroundColor = ConsoleColor.White;
+            Console.WriteLine("5 = ChannelAdapterBenchmark");
-            Console.WriteLine();
+            Console.WriteLine("6 = MqttTcpChannelBenchmark");
+            Console.WriteLine("7 = TcpPipesBenchmark");
+            Console.WriteLine("8 = MessageProcessingMqttConnectionContextBenchmark");
+            Console.WriteLine("9 = ServerProcessingBenchmark");
+            Console.WriteLine("a = MqttPacketReaderWriterBenchmark");
+            Console.WriteLine("b = RoundtripBenchmark");
+            Console.WriteLine("c = SubscribeBenchmark");
+            Console.WriteLine("d = UnsubscribeBenchmark");
+            Console.WriteLine("e = MessageDeliveryBenchmark");
 
-            for (var index = 0; index < _benchmarks.Count; index++)
+            var pressedKey = Console.ReadKey(true);
+            switch (pressedKey.KeyChar)
             {
-                var benchmark = _benchmarks[index];
+                case '1':
-
+                    BenchmarkRunner.Run<MessageProcessingBenchmark>();
-                if (_selectedBenchmarkIndex == index)
+                    break;
-                {
+                case '2':
-                    Console.Write("-> ");
+                    BenchmarkRunner.Run<SerializerBenchmark>();
-                }
+                    break;
-                else
+                case '3':
-                {
+                    BenchmarkRunner.Run<LoggerBenchmark>();
-                    Console.Write("   ");
+                    break;
-                }
+                case '4':
-
+                    BenchmarkRunner.Run<TopicFilterComparerBenchmark>();
-                Console.WriteLine(benchmark.Name);
+                    break;
+                case '5':
+                    BenchmarkRunner.Run<ChannelAdapterBenchmark>();
+                    break;
+                case '6':
+                    BenchmarkRunner.Run<MqttTcpChannelBenchmark>();
+                    break;
+                case '7':
+                    BenchmarkRunner.Run<TcpPipesBenchmark>();
+                    break;
+                case '8':
+                    BenchmarkRunner.Run<MessageProcessingMqttConnectionContextBenchmark>(new RuntimeCompareConfig());
+                    break;
+                case '9':
+                    BenchmarkRunner.Run<ServerProcessingBenchmark>();
+                    break;
+                case 'a':
+                    BenchmarkRunner.Run(typeof(MqttPacketReaderWriterBenchmark));
+                    break;
+                case 'b':
+                    BenchmarkRunner.Run<RoundtripProcessingBenchmark>();
+                    break;
+                case 'c':
+                    BenchmarkRunner.Run<SubscribeBenchmark>();
+                    break;
+                case 'd':
+                    BenchmarkRunner.Run<UnsubscribeBenchmark>();
+                    break;
+                case 'e':
+                    BenchmarkRunner.Run<MessageDeliveryBenchmark>();
+                    break;
             }
 
-            Console.WriteLine();
+            Console.ReadLine();
         }
     }
 }

Source/MQTTnet.Benchmarks/ReaderExtensionsBenchmark.cs

@@ -1,240 +0,0 @@
-using BenchmarkDotNet.Attributes;
-using BenchmarkDotNet.Jobs;
-using MQTTnet.Adapter;
-using MQTTnet.AspNetCore;
-using MQTTnet.Exceptions;
-using MQTTnet.Formatter;
-using MQTTnet.Packets;
-using System;
-using System.Buffers;
-using System.IO;
-using System.IO.Pipelines;
-using System.Linq;
-using System.Threading.Tasks;
-
-namespace MQTTnet.Benchmarks
-{
-    [SimpleJob(RuntimeMoniker.Net60)]
-    [RPlotExporter, RankColumn]
-    [MemoryDiagnoser]
-    public class ReaderExtensionsBenchmark
-    {
-        MqttPacketFormatterAdapter mqttPacketFormatter;
-        MemoryStream stream;
-
-        [GlobalSetup]
-        public void GlobalSetup()
-        {
-            mqttPacketFormatter = new MqttPacketFormatterAdapter(MqttProtocolVersion.V311, new MqttBufferWriter(4096, 65535));
-            var mqttMessage = new MqttApplicationMessageBuilder()
-            .WithTopic("topic")
-            .WithPayload(new byte[10 * 1024])
-            .Build();
-
-            var packet = MqttPacketFactories.Publish.Create(mqttMessage);
-
-            var buffer = mqttPacketFormatter.Encode(packet);
-            stream = new MemoryStream();
-            stream.Write(buffer.Packet);
-            stream.Write(buffer.Payload);
-            mqttPacketFormatter.Cleanup();
-        }
-
-        [Benchmark(Baseline = true)]
-        public async Task Before()
-        {
-            stream.Position = 0;
-            var input = PipeReader.Create(stream);
-
-            while (true)
-            {
-                ReadResult readResult;
-                var readTask = input.ReadAsync();
-                if (readTask.IsCompleted)
-                {
-                    readResult = readTask.Result;
-                }
-                else
-                {
-                    readResult = await readTask.ConfigureAwait(false);
-                }
-
-                var buffer = readResult.Buffer;
-
-                var consumed = buffer.Start;
-                var observed = buffer.Start;
-
-                try
-                {
-                    if (!buffer.IsEmpty)
-                    {
-                        if (ReaderExtensions_Before.TryDecode(mqttPacketFormatter, buffer, out var packet, out consumed, out observed, out var received))
-                        {
-                            break;
-                        }
-                    }
-                    else if (readResult.IsCompleted)
-                    {
-                        throw new MqttCommunicationException("Connection Aborted");
-                    }
-                }
-                finally
-                {
-                    // The buffer was sliced up to where it was consumed, so we can just advance to the start.
-                    // We mark examined as buffer.End so that if we didn't receive a full frame, we'll wait for more data
-                    // before yielding the read again.
-                    input.AdvanceTo(consumed, observed);
-                }
-            }
-        }
-
-        [Benchmark]
-        public async Task After()
-        {
-            stream.Position = 0;
-            var input = PipeReader.Create(stream);
-
-            while (true)
-            {
-                ReadResult readResult;
-                var readTask = input.ReadAsync();
-                if (readTask.IsCompleted)
-                {
-                    readResult = readTask.Result;
-                }
-                else
-                {
-                    readResult = await readTask.ConfigureAwait(false);
-                }
-
-                var buffer = readResult.Buffer;
-
-                var consumed = buffer.Start;
-                var observed = buffer.Start;
-
-                try
-                {
-                    if (!buffer.IsEmpty)
-                    {
-                        if (ReaderExtensions.TryDecode(mqttPacketFormatter, buffer, out var packet, out consumed, out observed, out var received))
-                        {
-                            break;
-                        }
-                    }
-                    else if (readResult.IsCompleted)
-                    {
-                        throw new MqttCommunicationException("Connection Aborted");
-                    }
-                }
-                finally
-                {
-                    // The buffer was sliced up to where it was consumed, so we can just advance to the start.
-                    // We mark examined as buffer.End so that if we didn't receive a full frame, we'll wait for more data
-                    // before yielding the read again.
-                    input.AdvanceTo(consumed, observed);
-                }
-            }
-        }
-
-        public static class ReaderExtensions_Before
-        {
-            public static bool TryDecode(MqttPacketFormatterAdapter formatter,
-                in ReadOnlySequence<byte> input,
-                out MqttPacket packet,
-                out SequencePosition consumed,
-                out SequencePosition observed,
-                out int bytesRead)
-            {
-                if (formatter == null) throw new ArgumentNullException(nameof(formatter));
-
-                packet = null;
-                consumed = input.Start;
-                observed = input.End;
-                bytesRead = 0;
-                var copy = input;
-
-                if (copy.Length < 2)
-                {
-                    return false;
-                }
-
-                var fixedHeader = copy.First.Span[0];
-                if (!TryReadBodyLength(ref copy, out int headerLength, out var bodyLength))
-                {
-                    return false;
-                }
-
-                if (copy.Length < bodyLength)
-                {
-                    return false;
-                }
-
-                var bodySlice = copy.Slice(0, bodyLength);
-                var buffer = GetMemory(bodySlice).ToArray();
-
-                var receivedMqttPacket = new ReceivedMqttPacket(fixedHeader, new ArraySegment<byte>(buffer, 0, buffer.Length), buffer.Length + 2);
-
-                if (formatter.ProtocolVersion == MqttProtocolVersion.Unknown)
-                {
-                    formatter.DetectProtocolVersion(receivedMqttPacket);
-                }
-
-                packet = formatter.Decode(receivedMqttPacket);
-                consumed = bodySlice.End;
-                observed = bodySlice.End;
-                bytesRead = headerLength + bodyLength;
-                return true;
-            }
-
-            static ReadOnlyMemory<byte> GetMemory(in ReadOnlySequence<byte> input)
-            {
-                if (input.IsSingleSegment)
-                {
-                    return input.First;
-                }
-
-                // Should be rare
-                return input.ToArray();
-            }
-
-            static bool TryReadBodyLength(ref ReadOnlySequence<byte> input, out int headerLength, out int bodyLength)
-            {
-                // Alorithm taken from https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/errata01/os/mqtt-v3.1.1-errata01-os-complete.html.
-                var multiplier = 1;
-                var value = 0;
-                byte encodedByte;
-                var index = 1;
-                headerLength = 0;
-                bodyLength = 0;
-
-                var temp = GetMemory(input.Slice(0, Math.Min(5, input.Length))).Span;
-
-                do
-                {
-                    if (index == temp.Length)
-                    {
-                        return false;
-                    }
-
-                    encodedByte = temp[index];
-                    index++;
-
-                    value += (byte)(encodedByte & 127) * multiplier;
-                    if (multiplier > 128 * 128 * 128)
-                    {
-                        throw new MqttProtocolViolationException($"Remaining length is invalid (Data={string.Join(",", temp.Slice(1, index).ToArray())}).");
-                    }
-
-                    multiplier *= 128;
-                } while ((encodedByte & 128) != 0);
-
-                input = input.Slice(index);
-
-                headerLength = index;
-                bodyLength = value;
-                return true;
-            }
-        }
-
-    }
-}

Source/MQTTnet.Benchmarks/RoundtripProcessingBenchmark.cs

@@ -8,7 +8,7 @@ namespace MQTTnet.Benchmarks
     [SimpleJob(RuntimeMoniker.Net60)]
     [RPlotExporter, RankColumn]
     [MemoryDiagnoser]
-    public class RoundtripProcessingBenchmark : BaseBenchmark
+    public class RoundtripProcessingBenchmark
     {
         [GlobalSetup]
         public void GlobalSetup()

Source/MQTTnet.Benchmarks/SerializerBenchmark.cs

@@ -104,7 +104,7 @@ namespace MQTTnet.Benchmarks
                 return Task.FromResult(count);
             }
 
-            public Task WriteAsync(ArraySegment<byte> buffer, bool isEndOfPacket, CancellationToken cancellationToken)
+            public Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
             {
                 throw new NotSupportedException();
             }

Source/MQTTnet.Benchmarks/ServerProcessingBenchmark.cs

@@ -1,7 +1,3 @@
-// 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.
-
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
 using MQTTnet.Tests.Mockups;
@@ -12,7 +8,7 @@ namespace MQTTnet.Benchmarks
     [SimpleJob(RuntimeMoniker.Net60)]
     [RPlotExporter, RankColumn]
     [MemoryDiagnoser]
-    public class ServerProcessingBenchmark : BaseBenchmark
+    public class ServerProcessingBenchmark
     {
         [GlobalSetup]
         public void GlobalSetup()

Source/MQTTnet.Benchmarks/SubscribeBenchmark.cs

@@ -1,7 +1,3 @@
-// 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.
-
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
 using MQTTnet.Client;
@@ -12,7 +8,7 @@ using System.Linq;
 namespace MQTTnet.Benchmarks
 {
     [MemoryDiagnoser]
-    public class SubscribeBenchmark : BaseBenchmark
+    public class SubscribeBenchmark
     {
         MqttServer _mqttServer;
         IMqttClient _mqttClient;

Source/MQTTnet.Benchmarks/TcpPipesBenchmark.cs

@@ -15,7 +15,7 @@ namespace MQTTnet.Benchmarks
 {
     [SimpleJob(RuntimeMoniker.Net60)]
     [MemoryDiagnoser]
-    public class TcpPipesBenchmark : BaseBenchmark
+    public class TcpPipesBenchmark
     {
         IDuplexPipe _client;
         IDuplexPipe _server;

Source/MQTTnet.Benchmarks/TopicFilterComparerBenchmark.cs

@@ -11,7 +11,7 @@ namespace MQTTnet.Benchmarks
     [SimpleJob(RuntimeMoniker.Net60)]
     [RPlotExporter]
     [MemoryDiagnoser]
-    public class TopicFilterComparerBenchmark : BaseBenchmark
+    public class TopicFilterComparerBenchmark
     {
         static readonly char[] TopicLevelSeparator = { '/' };
 

Source/MQTTnet.Benchmarks/TopicGenerator.cs

@@ -1,30 +1,31 @@
 using System;
 using System.Collections.Generic;
+using System.Text;
 
 namespace MQTTnet.Benchmarks
 {
     public class TopicGenerator
     {
         public static void Generate(
-            int numPublishers,
+           int numPublishers, int numTopicsPerPublisher,
-            int numTopicsPerPublisher,
+           out Dictionary<string, List<string>> topicsByPublisher,
-            out Dictionary<string, List<string>> topicsByPublisher,
+           out Dictionary<string, List<string>> singleWildcardTopicsByPublisher,
-            out Dictionary<string, List<string>> singleWildcardTopicsByPublisher,
+           out Dictionary<string, List<string>> multiWildcardTopicsByPublisher
-            out Dictionary<string, List<string>> multiWildcardTopicsByPublisher)
+           )
         {
             topicsByPublisher = new Dictionary<string, List<string>>();
             singleWildcardTopicsByPublisher = new Dictionary<string, List<string>>();
             multiWildcardTopicsByPublisher = new Dictionary<string, List<string>>();
 
             // Find some reasonable distribution across three topic levels
-            var topicsPerLevel = (int)Math.Pow(numTopicsPerPublisher, 1.0 / 3.0);
+            var topicsPerLevel = (int)Math.Pow(numTopicsPerPublisher, (1.0 / 3.0));
             if (topicsPerLevel <= 0)
             {
                 topicsPerLevel = 1;
             }
 
-            var numLevel1Topics = topicsPerLevel;
+            int numLevel1Topics = topicsPerLevel;
-            var numLevel2Topics = topicsPerLevel;
+            int numLevel2Topics = topicsPerLevel;
 
             var maxNumLevel3Topics = 1 + (int)((double)numTopicsPerPublisher / numLevel1Topics / numLevel2Topics);
             if (maxNumLevel3Topics <= 0)
@@ -34,7 +35,7 @@ namespace MQTTnet.Benchmarks
 
             for (var p = 0; p < numPublishers; ++p)
             {
-                var publisherTopicCount = 0;
+                int publisherTopicCount = 0;
                 var publisherName = "pub" + p;
                 for (var l1 = 0; l1 < numLevel1Topics; ++l1)
                 {
@@ -43,22 +44,19 @@ namespace MQTTnet.Benchmarks
                         for (var l3 = 0; l3 < maxNumLevel3Topics; ++l3)
                         {
                             if (publisherTopicCount >= numTopicsPerPublisher)
-                            {
                                 break;
-                            }
 
-                            var topic = $"{publisherName}/building{l1 + 1}/level{l2 + 1}/sensor{l3 + 1}";
+                            var topic = string.Format("{0}/building{1}/level{2}/sensor{3}", publisherName, l1 + 1, l2 + 1, l3 + 1);
                             AddPublisherTopic(publisherName, topic, topicsByPublisher);
 
                             if (l2 == 0)
                             {
-                                var singleWildcardTopic = $"{publisherName}/building{l1 + 1}/+/sensor{l3 + 1}";
+                                var singleWildcardTopic = string.Format("{0}/building{1}/+/sensor{2}", publisherName, l1 + 1, l3 + 1);
                                 AddPublisherTopic(publisherName, singleWildcardTopic, singleWildcardTopicsByPublisher);
                             }
-
+                            if ((l1 == 0) && (l3 == 0))
-                            if (l1 == 0 && l3 == 0)
                             {
-                                var multiWildcardTopic = $"{publisherName}/+/level{l2 + 1}/+";
+                                var multiWildcardTopic = string.Format("{0}/+/level{1}/+", publisherName, l2 + 1);
                                 AddPublisherTopic(publisherName, multiWildcardTopic, multiWildcardTopicsByPublisher);
                             }
 
@@ -77,7 +75,6 @@ namespace MQTTnet.Benchmarks
                 topicList = new List<string>();
                 topicsByPublisher.Add(publisherName, topicList);
             }
-
             topicList.Add(topic);
         }
     }

Source/MQTTnet.Benchmarks/UnsubscribeBenchmark.cs

@@ -1,7 +1,3 @@
-// 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.
-
 using BenchmarkDotNet.Attributes;
 using MQTTnet.Client;
 using MQTTnet.Server;
@@ -11,7 +7,7 @@ using System.Linq;
 namespace MQTTnet.Benchmarks
 {
     [MemoryDiagnoser]
-    public class UnsubscribeBenchmark : BaseBenchmark 
+    public class UnsubscribeBenchmark
     {
         MqttServer _mqttServer;
         IMqttClient _mqttClient;

Source/MQTTnet.Benchmarks/packages.config

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="BenchmarkDotNet" version="0.10.14" targetFramework="net462" />
+  <package id="BenchmarkDotNet.Core" version="0.10.14" targetFramework="net462" />
+  <package id="BenchmarkDotNet.Toolchains.Roslyn" version="0.10.14" targetFramework="net462" />
+  <package id="Microsoft.CodeAnalysis.Analyzers" version="1.1.0" targetFramework="net462" />
+  <package id="Microsoft.CodeAnalysis.Common" version="2.6.1" targetFramework="net462" />
+  <package id="Microsoft.CodeAnalysis.CSharp" version="2.6.1" targetFramework="net462" />
+  <package id="Microsoft.DotNet.InternalAbstractions" version="1.0.0" targetFramework="net462" />
+  <package id="Microsoft.DotNet.PlatformAbstractions" version="1.1.1" targetFramework="net462" />
+  <package id="Microsoft.Win32.Registry" version="4.3.0" targetFramework="net462" />
+  <package id="System.AppContext" version="4.3.0" targetFramework="net462" />
+  <package id="System.Collections" version="4.3.0" targetFramework="net462" />
+  <package id="System.Collections.Concurrent" version="4.3.0" targetFramework="net462" />
+  <package id="System.Collections.Immutable" version="1.3.1" targetFramework="net462" />
+  <package id="System.Console" version="4.3.0" targetFramework="net462" />
+  <package id="System.Diagnostics.Debug" version="4.3.0" targetFramework="net462" />
+  <package id="System.Diagnostics.FileVersionInfo" version="4.3.0" targetFramework="net462" />
+  <package id="System.Diagnostics.StackTrace" version="4.3.0" targetFramework="net462" />
+  <package id="System.Diagnostics.Tools" version="4.3.0" targetFramework="net462" />
+  <package id="System.Dynamic.Runtime" version="4.3.0" targetFramework="net462" />
+  <package id="System.Globalization" version="4.3.0" targetFramework="net462" />
+  <package id="System.IO.Compression" version="4.3.0" targetFramework="net462" />
+  <package id="System.IO.FileSystem" version="4.3.0" targetFramework="net462" />
+  <package id="System.IO.FileSystem.Primitives" version="4.3.0" targetFramework="net462" />
+  <package id="System.Linq" version="4.3.0" targetFramework="net462" />
+  <package id="System.Linq.Expressions" version="4.3.0" targetFramework="net462" />
+  <package id="System.Reflection" version="4.3.0" targetFramework="net462" />
+  <package id="System.Reflection.Metadata" version="1.4.2" targetFramework="net462" />
+  <package id="System.Resources.ResourceManager" version="4.3.0" targetFramework="net462" />
+  <package id="System.Runtime" version="4.3.0" targetFramework="net462" />
+  <package id="System.Runtime.Extensions" version="4.3.0" targetFramework="net462" />
+  <package id="System.Runtime.InteropServices" version="4.3.0" targetFramework="net462" />
+  <package id="System.Runtime.Numerics" version="4.3.0" targetFramework="net462" />
+  <package id="System.Security.Cryptography.Algorithms" version="4.3.0" targetFramework="net462" />
+  <package id="System.Security.Cryptography.Encoding" version="4.3.0" targetFramework="net462" />
+  <package id="System.Security.Cryptography.Primitives" version="4.3.0" targetFramework="net462" />
+  <package id="System.Security.Cryptography.X509Certificates" version="4.3.0" targetFramework="net462" />
+  <package id="System.Text.Encoding" version="4.3.0" targetFramework="net462" />
+  <package id="System.Text.Encoding.CodePages" version="4.3.0" targetFramework="net462" />
+  <package id="System.Text.Encoding.Extensions" version="4.3.0" targetFramework="net462" />
+  <package id="System.Threading" version="4.3.0" targetFramework="net462" />
+  <package id="System.Threading.Tasks" version="4.3.0" targetFramework="net462" />
+  <package id="System.Threading.Tasks.Extensions" version="4.3.0" targetFramework="net462" />
+  <package id="System.Threading.Tasks.Parallel" version="4.3.0" targetFramework="net462" />
+  <package id="System.Threading.Thread" version="4.3.0" targetFramework="net462" />
+  <package id="System.ValueTuple" version="4.3.0" targetFramework="net462" />
+  <package id="System.Xml.ReaderWriter" version="4.3.0" targetFramework="net462" />
+  <package id="System.Xml.XDocument" version="4.3.0" targetFramework="net462" />
+  <package id="System.Xml.XmlDocument" version="4.3.0" targetFramework="net462" />
+  <package id="System.Xml.XmlSerializer" version="4.3.0" targetFramework="net462" />
+  <package id="System.Xml.XPath" version="4.3.0" targetFramework="net462" />
+  <package id="System.Xml.XPath.XDocument" version="4.3.0" targetFramework="net462" />
+</packages>

Source/MQTTnet.Extensions.ManagedClient/IManagedMqttClient.cs

@@ -43,7 +43,7 @@ namespace MQTTnet.Extensions.ManagedClient
         
         Task StartAsync(ManagedMqttClientOptions options);
         
-        Task StopAsync(bool cleanDisconnect = true);
+        Task StopAsync();
         
         Task SubscribeAsync(ICollection<MqttTopicFilter> topicFilters);
         

Source/MQTTnet.Extensions.ManagedClient/MQTTnet.Extensions.ManagedClient.csproj

@@ -33,7 +33,7 @@
         <PackageReleaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</PackageReleaseNotes>
         <DisableImplicitAspNetCoreAnalyzers>true</DisableImplicitAspNetCoreAnalyzers>
         <GenerateDocumentationFile>true</GenerateDocumentationFile>
-        <NoWarn>1591;NETSDK1138</NoWarn>
+        <NoWarn>1591</NoWarn>
     </PropertyGroup>
 
     <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0'">

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs

@@ -62,7 +62,6 @@ namespace MQTTnet.Extensions.ManagedClient
         CancellationTokenSource _publishingCancellationToken;
 
         ManagedMqttClientStorageManager _storageManager;
-        bool _isCleanDisconnect;
 
         public ManagedMqttClient(IMqttClient mqttClient, IMqttNetLogger logger)
         {
@@ -161,14 +160,14 @@ namespace MQTTnet.Extensions.ManagedClient
                 throw new InvalidOperationException("call StartAsync before publishing messages");
             }
 
-            MqttTopicValidator.ThrowIfInvalid(applicationMessage.ApplicationMessage);
+            MqttTopicValidator.ThrowIfInvalid(applicationMessage.ApplicationMessage.Topic);
 
             ManagedMqttApplicationMessage removedMessage = null;
             ApplicationMessageSkippedEventArgs applicationMessageSkippedEventArgs = null;
 
             try
             {
-                using (await _messageQueueLock.EnterAsync().ConfigureAwait(false))
+                using (await _messageQueueLock.WaitAsync(CancellationToken.None).ConfigureAwait(false))
                 {
                     if (_messageQueue.Count >= Options.MaxPendingMessages)
                     {
@@ -256,12 +255,10 @@ namespace MQTTnet.Extensions.ManagedClient
             _logger.Info("Started");
         }
 
-        public async Task StopAsync(bool cleanDisconnect = true)
+        public async Task StopAsync()
         {
             ThrowIfDisposed();
 
-            _isCleanDisconnect = cleanDisconnect;
-            
             StopPublishing();
             StopMaintainingConnection();
 
@@ -299,7 +296,7 @@ namespace MQTTnet.Extensions.ManagedClient
 
             _subscriptionsQueuedSignal.Release();
 
-            return CompletedTask.Instance;
+            return Task.FromResult(0);
         }
 
         public Task UnsubscribeAsync(ICollection<string> topics)
@@ -322,7 +319,7 @@ namespace MQTTnet.Extensions.ManagedClient
 
             _subscriptionsQueuedSignal.Release();
 
-            return CompletedTask.Instance;
+            return Task.FromResult(0);
         }
 
         protected override void Dispose(bool disposing)
@@ -385,12 +382,9 @@ namespace MQTTnet.Extensions.ManagedClient
                 {
                     try
                     {
-                        if (_isCleanDisconnect)
+                        using (var disconnectTimeout = new CancellationTokenSource(Options.ClientOptions.Timeout))
                         {
-                            using (var disconnectTimeout = new CancellationTokenSource(Options.ClientOptions.Timeout))
+                            await InternalClient.DisconnectAsync(new MqttClientDisconnectOptions(), disconnectTimeout.Token).ConfigureAwait(false);
-                            {
-                                await InternalClient.DisconnectAsync(new MqttClientDisconnectOptions(), disconnectTimeout.Token).ConfigureAwait(false);
-                            }
                         }
                     }
                     catch (OperationCanceledException)
@@ -699,7 +693,7 @@ namespace MQTTnet.Extensions.ManagedClient
             {
                 await InternalClient.PublishAsync(message.ApplicationMessage).ConfigureAwait(false);
 
-                using (await _messageQueueLock.EnterAsync().ConfigureAwait(false)) //lock to avoid conflict with this.PublishAsync
+                using (await _messageQueueLock.WaitAsync(CancellationToken.None).ConfigureAwait(false)) //lock to avoid conflict with this.PublishAsync
                 {
                     // While publishing this message, this.PublishAsync could have booted this
                     // message off the queue to make room for another (when using a cap
@@ -730,7 +724,7 @@ namespace MQTTnet.Extensions.ManagedClient
                     //contradict the expected behavior of QoS 1 and 2, that's also true
                     //for the usage of a message queue cap, so it's still consistent
                     //with prior behavior in that way.
-                    using (await _messageQueueLock.EnterAsync().ConfigureAwait(false)) //lock to avoid conflict with this.PublishAsync
+                    using (await _messageQueueLock.WaitAsync(CancellationToken.None).ConfigureAwait(false)) //lock to avoid conflict with this.PublishAsync
                     {
                         _messageQueue.RemoveFirst(i => i.Id.Equals(message.Id));
 

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClientStorageManager.cs

@@ -34,7 +34,7 @@ namespace MQTTnet.Extensions.ManagedClient
         {
             if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
 
-            using (await _messagesLock.EnterAsync().ConfigureAwait(false))
+            using (await _messagesLock.WaitAsync(CancellationToken.None).ConfigureAwait(false))
             {
                 _messages.Add(applicationMessage);
                 await SaveAsync().ConfigureAwait(false);
@@ -45,7 +45,7 @@ namespace MQTTnet.Extensions.ManagedClient
         {
             if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
 
-            using (await _messagesLock.EnterAsync().ConfigureAwait(false))
+            using (await _messagesLock.WaitAsync(CancellationToken.None).ConfigureAwait(false))
             {
                 var index = _messages.IndexOf(applicationMessage);
                 if (index == -1)

Source/MQTTnet.Extensions.Rpc/MQTTnet.Extensions.Rpc.csproj

@@ -33,8 +33,7 @@
         <PackageReleaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</PackageReleaseNotes>
         <DisableImplicitAspNetCoreAnalyzers>true</DisableImplicitAspNetCoreAnalyzers>
         <GenerateDocumentationFile>true</GenerateDocumentationFile>
-        <NoWarn>1591;NETSDK1138</NoWarn>
+        <NoWarn>1591</NoWarn>
-        <LangVersion>7.3</LangVersion>
     </PropertyGroup>
 
     <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0'">

Source/MQTTnet.Extensions.Rpc/MqttFactoryExtensions.cs

@@ -11,12 +11,10 @@ namespace MQTTnet.Extensions.Rpc
     {
         public static IMqttRpcClient CreateMqttRpcClient(this MqttFactory factory, IMqttClient mqttClient)
         {
-            return factory.CreateMqttRpcClient(
+            return factory.CreateMqttRpcClient(mqttClient, new MqttRpcClientOptions
-                mqttClient,
+            {
-                new MqttRpcClientOptions
+                TopicGenerationStrategy = new DefaultMqttRpcClientTopicGenerationStrategy()
-                {
+            });
-                    TopicGenerationStrategy = new DefaultMqttRpcClientTopicGenerationStrategy()
-                });
         }
 
         public static IMqttRpcClient CreateMqttRpcClient(this MqttFactory _, IMqttClient mqttClient, MqttRpcClientOptions rpcClientOptions)

Source/MQTTnet.Extensions.Rpc/MqttRpcClient.cs

@@ -2,24 +2,23 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using MQTTnet.Client;
+using MQTTnet.Exceptions;
+using MQTTnet.Protocol;
 using System;
 using System.Collections.Concurrent;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Client;
+using MQTTnet.Implementations;
-using MQTTnet.Exceptions;
-using MQTTnet.Internal;
-using MQTTnet.Protocol;
 
 namespace MQTTnet.Extensions.Rpc
 {
     public sealed class MqttRpcClient : IMqttRpcClient
     {
+        readonly ConcurrentDictionary<string, TaskCompletionSource<byte[]>> _waitingCalls = new ConcurrentDictionary<string, TaskCompletionSource<byte[]>>();
         readonly IMqttClient _mqttClient;
         readonly MqttRpcClientOptions _options;
         
-        readonly ConcurrentDictionary<string, AsyncTaskCompletionSource<byte[]>> _waitingCalls = new ConcurrentDictionary<string, AsyncTaskCompletionSource<byte[]>>();
-        
         public MqttRpcClient(IMqttClient mqttClient, MqttRpcClientOptions options)
         {
             _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
@@ -28,18 +27,6 @@ namespace MQTTnet.Extensions.Rpc
             _mqttClient.ApplicationMessageReceivedAsync += HandleApplicationMessageReceivedAsync;
         }
 
-        public void Dispose()
-        {
-            _mqttClient.ApplicationMessageReceivedAsync -= HandleApplicationMessageReceivedAsync;
-
-            foreach (var tcs in _waitingCalls)
-            {
-                tcs.Value.TrySetCanceled();
-            }
-
-            _waitingCalls.Clear();
-        }
-
         public async Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
         {
             using (var timeoutToken = new CancellationTokenSource(timeout))
@@ -62,13 +49,15 @@ namespace MQTTnet.Extensions.Rpc
 
         public async Task<byte[]> ExecuteAsync(string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, CancellationToken cancellationToken = default)
         {
-            if (methodName == null)
+            if (methodName == null) throw new ArgumentNullException(nameof(methodName));
-            {
-                throw new ArgumentNullException(nameof(methodName));
-            }
             
-            var context = new TopicGenerationContext(_mqttClient, _options, methodName, qualityOfServiceLevel);
+            var topicNames = _options.TopicGenerationStrategy.CreateRpcTopics(new TopicGenerationContext
-            var topicNames = _options.TopicGenerationStrategy.CreateRpcTopics(context);
+            {
+                MethodName = methodName,
+                QualityOfServiceLevel = qualityOfServiceLevel,
+                MqttClient = _mqttClient,
+                Options = _options
+            });
 
             var requestTopic = topicNames.RequestTopic;
             var responseTopic = topicNames.ResponseTopic;
@@ -83,7 +72,8 @@ namespace MQTTnet.Extensions.Rpc
                 throw new MqttProtocolViolationException("RPC response topic is empty.");
             }
 
-            var requestMessage = new MqttApplicationMessageBuilder().WithTopic(requestTopic)
+            var requestMessage = new MqttApplicationMessageBuilder()
+                .WithTopic(requestTopic)
                 .WithPayload(payload)
                 .WithQualityOfServiceLevel(qualityOfServiceLevel)
                 .WithResponseTopic(responseTopic)
@@ -91,23 +81,25 @@ namespace MQTTnet.Extensions.Rpc
 
             try
             {
-                var awaitable = new AsyncTaskCompletionSource<byte[]>();
+#if NET452
+                var awaitable = new TaskCompletionSource<byte[]>();
+#else
+                var awaitable = new TaskCompletionSource<byte[]>(TaskCreationOptions.RunContinuationsAsynchronously);
+#endif
 
                 if (!_waitingCalls.TryAdd(responseTopic, awaitable))
                 {
                     throw new InvalidOperationException();
                 }
 
-                var subscribeOptions = new MqttClientSubscribeOptionsBuilder().WithTopicFilter(responseTopic, qualityOfServiceLevel).Build();
+                var subscribeOptions = new MqttClientSubscribeOptionsBuilder()
+                    .WithTopicFilter(responseTopic, qualityOfServiceLevel)
+                    .Build();
 
                 await _mqttClient.SubscribeAsync(subscribeOptions, cancellationToken).ConfigureAwait(false);
                 await _mqttClient.PublishAsync(requestMessage, cancellationToken).ConfigureAwait(false);
 
-                using (cancellationToken.Register(
+                using (cancellationToken.Register(() => { awaitable.TrySetCanceled(); }))
-                           () =>
-                           {
-                               awaitable.TrySetCanceled();
-                           }))
                 {
                     return await awaitable.Task.ConfigureAwait(false);
                 }
@@ -116,7 +108,7 @@ namespace MQTTnet.Extensions.Rpc
             {
                 _waitingCalls.TryRemove(responseTopic, out _);
                 
-                await _mqttClient.UnsubscribeAsync(responseTopic, CancellationToken.None).ConfigureAwait(false);
+                await _mqttClient.UnsubscribeAsync(responseTopic).ConfigureAwait(false);
             }
         }
 
@@ -124,15 +116,31 @@ namespace MQTTnet.Extensions.Rpc
         {
             if (!_waitingCalls.TryRemove(eventArgs.ApplicationMessage.Topic, out var awaitable))
             {
-                return CompletedTask.Instance;
+                return PlatformAbstractionLayer.CompletedTask;
             }
 
+#if NET452
+            Task.Run(() => awaitable.TrySetResult(eventArgs.ApplicationMessage.Payload));
+#else
             awaitable.TrySetResult(eventArgs.ApplicationMessage.Payload);
+#endif
 
             // Set this message to handled to that other code can avoid execution etc.
             eventArgs.IsHandled = true;
 
-            return CompletedTask.Instance;
+            return PlatformAbstractionLayer.CompletedTask;
+        }
+
+        public void Dispose()
+        {
+            _mqttClient.ApplicationMessageReceivedAsync -= HandleApplicationMessageReceivedAsync;
+
+            foreach (var tcs in _waitingCalls)
+            {
+                tcs.Value.TrySetCanceled();
+            }
+
+            _waitingCalls.Clear();
         }
     }
 }

Source/MQTTnet.Extensions.Rpc/Options/MqttRpcClientOptionsBuilder.cs

@@ -10,6 +10,13 @@ namespace MQTTnet.Extensions.Rpc
     {
         IMqttRpcClientTopicGenerationStrategy _topicGenerationStrategy = new DefaultMqttRpcClientTopicGenerationStrategy();
 
+        public MqttRpcClientOptionsBuilder WithTopicGenerationStrategy(IMqttRpcClientTopicGenerationStrategy value)
+        {
+            _topicGenerationStrategy = value ?? throw new ArgumentNullException(nameof(value));
+
+            return this;
+        }
+
         public MqttRpcClientOptions Build()
         {
             return new MqttRpcClientOptions
@@ -17,12 +24,5 @@ namespace MQTTnet.Extensions.Rpc
                 TopicGenerationStrategy = _topicGenerationStrategy
             };
         }
-
-        public MqttRpcClientOptionsBuilder WithTopicGenerationStrategy(IMqttRpcClientTopicGenerationStrategy value)
-        {
-            _topicGenerationStrategy = value ?? throw new ArgumentNullException(nameof(value));
-
-            return this;
-        }
     }
 }

Source/MQTTnet.Extensions.Rpc/Options/TopicGeneration/DefaultMqttRpcClientTopicGenerationStrategy.cs

@@ -10,11 +10,6 @@ namespace MQTTnet.Extensions.Rpc
     {
         public MqttRpcTopicPair CreateRpcTopics(TopicGenerationContext context)
         {
-            if (context == null)
-            {
-                throw new ArgumentNullException(nameof(context));
-            }
-
             if (context.MethodName.Contains("/") || context.MethodName.Contains("+") || context.MethodName.Contains("#"))
             {
                 throw new ArgumentException("The method name cannot contain /, + or #.");

Source/MQTTnet.Extensions.Rpc/Options/TopicGeneration/TopicGenerationContext.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using MQTTnet.Client;
 using MQTTnet.Protocol;
 
@@ -10,29 +9,20 @@ namespace MQTTnet.Extensions.Rpc
 {
     public sealed class TopicGenerationContext
     {
-        public TopicGenerationContext(IMqttClient mqttClient, MqttRpcClientOptions options, string methodName, MqttQualityOfServiceLevel qualityOfServiceLevel)
+        public string MethodName { get; set; }
-        {
-            MethodName = methodName ?? throw new ArgumentNullException(nameof(methodName));
-            QualityOfServiceLevel = qualityOfServiceLevel;
-            MqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
-            Options = options ?? throw new ArgumentNullException(nameof(options));
-        }
-
-        public string MethodName { get; }
-
-        public IMqttClient MqttClient { get; }
-
-        public MqttRpcClientOptions Options { get; }
 
         /// <summary>
-        ///     Gets or sets the quality of service level.
+        /// Gets or sets the quality of service level.
-        ///     The Quality of Service (QoS) level is an agreement between the sender of a message and the receiver of a message
+        /// The Quality of Service (QoS) level is an agreement between the sender of a message and the receiver of a message that defines the guarantee of delivery for a specific message.
-        ///     that defines the guarantee of delivery for a specific message.
+        /// There are 3 QoS levels in MQTT:
-        ///     There are 3 QoS levels in MQTT:
+        /// - At most once  (0): Message gets delivered no time, once or multiple times.
-        ///     - At most once  (0): Message gets delivered no time, once or multiple times.
+        /// - At least once (1): Message gets delivered at least once (one time or more often).
-        ///     - At least once (1): Message gets delivered at least once (one time or more often).
+        /// - Exactly once  (2): Message gets delivered exactly once (It's ensured that the message only comes once).
-        ///     - Exactly once  (2): Message gets delivered exactly once (It's ensured that the message only comes once).
         /// </summary>
-        public MqttQualityOfServiceLevel QualityOfServiceLevel { get; }
+        public MqttQualityOfServiceLevel QualityOfServiceLevel { get; set; }
+
+        public IMqttClient MqttClient { get; set; }
+
+        public MqttRpcClientOptions Options { get; set; }
     }
 }

Source/MQTTnet.Extensions.WebSocket4Net/MQTTnet.Extensions.WebSocket4Net.csproj

@@ -33,8 +33,7 @@
         <PackageReleaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</PackageReleaseNotes>
         <DisableImplicitAspNetCoreAnalyzers>true</DisableImplicitAspNetCoreAnalyzers>
         <GenerateDocumentationFile>true</GenerateDocumentationFile>
-        <NoWarn>1591;NETSDK1138</NoWarn>
+        <NoWarn>1591</NoWarn>
-        <LangVersion>7.3</LangVersion>
     </PropertyGroup>
 
     <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0'">

Source/MQTTnet.Extensions.WebSocket4Net/MqttFactoryExtensions.cs

@@ -10,10 +10,7 @@ namespace MQTTnet.Extensions.WebSocket4Net
     {
         public static MqttFactory UseWebSocket4Net(this MqttFactory mqttFactory)
         {
-            if (mqttFactory == null)
+            if (mqttFactory == null) throw new ArgumentNullException(nameof(mqttFactory));
-            {
-                throw new ArgumentNullException(nameof(mqttFactory));
-            }
 
             return mqttFactory.UseClientAdapterFactory(new WebSocket4NetMqttClientAdapterFactory());
         }

Source/MQTTnet.Extensions.WebSocket4Net/WebSocket4NetMqttChannel.cs

@@ -5,7 +5,6 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.Linq;
 using System.Net;
 using System.Security.Authentication;
@@ -15,17 +14,16 @@ using System.Threading.Tasks;
 using MQTTnet.Channel;
 using MQTTnet.Client;
 using MQTTnet.Exceptions;
-using MQTTnet.Internal;
 using SuperSocket.ClientEngine;
 using WebSocket4Net;
-using DataReceivedEventArgs = WebSocket4Net.DataReceivedEventArgs;
 
 namespace MQTTnet.Extensions.WebSocket4Net
 {
     public sealed class WebSocket4NetMqttChannel : IMqttChannel
     {
-        readonly MqttClientOptions _clientOptions;
         readonly BlockingCollection<byte> _receiveBuffer = new BlockingCollection<byte>();
+
+        readonly MqttClientOptions _clientOptions;
         readonly MqttClientWebSocketOptions _webSocketOptions;
 
         WebSocket _webSocket;
@@ -36,13 +34,13 @@ namespace MQTTnet.Extensions.WebSocket4Net
             _webSocketOptions = webSocketOptions ?? throw new ArgumentNullException(nameof(webSocketOptions));
         }
 
-        public X509Certificate2 ClientCertificate { get; }
-
         public string Endpoint => _webSocketOptions.Uri;
 
         public bool IsSecureConnection { get; private set; }
 
-        public Task ConnectAsync(CancellationToken cancellationToken)
+        public X509Certificate2 ClientCertificate { get; }
+
+        public async Task ConnectAsync(CancellationToken cancellationToken)
         {
             var uri = _webSocketOptions.Uri;
             if (!uri.StartsWith("ws://", StringComparison.OrdinalIgnoreCase) && !uri.StartsWith("wss://", StringComparison.OrdinalIgnoreCase))
@@ -57,12 +55,10 @@ namespace MQTTnet.Extensions.WebSocket4Net
                 }
             }
 
-            IsSecureConnection = uri.StartsWith("wss://", StringComparison.OrdinalIgnoreCase);
+#if NET48 || NETCOREAPP3_1 || NET5 || NET6
-
+            var sslProtocols = _webSocketOptions?.TlsOptions?.SslProtocol ?? SslProtocols.Tls12 | SslProtocols.Tls13;
-#if NET48 || NETCOREAPP3_0_OR_GREATER
-            var sslProtocols = _webSocketOptions.TlsOptions?.SslProtocol ?? SslProtocols.Tls12 | SslProtocols.Tls13;
 #else
-            var sslProtocols = _webSocketOptions.TlsOptions?.SslProtocol ?? SslProtocols.Tls12 | (SslProtocols)0x00003000 /*Tls13*/;
+            var sslProtocols = _webSocketOptions?.TlsOptions?.SslProtocol ?? SslProtocols.Tls12 | (SslProtocols)0x00003000 /*Tls13*/;
 #endif
 
             var subProtocol = _webSocketOptions.SubProtocols.FirstOrDefault() ?? string.Empty;
@@ -93,7 +89,7 @@ namespace MQTTnet.Extensions.WebSocket4Net
             var receiveBufferSize = 0;
 
             var certificates = new X509CertificateCollection();
-            if (_webSocketOptions.TlsOptions?.Certificates != null)
+            if (_webSocketOptions?.TlsOptions?.Certificates != null)
             {
                 foreach (var certificate in _webSocketOptions.TlsOptions.Certificates)
                 {
@@ -110,13 +106,15 @@ namespace MQTTnet.Extensions.WebSocket4Net
                 NoDelay = true,
                 Security =
                 {
-                    AllowUnstrustedCertificate = _webSocketOptions.TlsOptions?.AllowUntrustedCertificates == true,
+                    AllowUnstrustedCertificate = _webSocketOptions?.TlsOptions?.AllowUntrustedCertificates == true,
-                    AllowCertificateChainErrors = _webSocketOptions.TlsOptions?.IgnoreCertificateChainErrors == true,
+                    AllowCertificateChainErrors = _webSocketOptions?.TlsOptions?.IgnoreCertificateChainErrors == true,
                     Certificates = certificates
                 }
             };
 
-            return ConnectInternalAsync(cancellationToken);
+            await ConnectInternalAsync(cancellationToken).ConfigureAwait(false);
+            
+            IsSecureConnection = uri.StartsWith("wss://", StringComparison.OrdinalIgnoreCase);
         }
 
         public Task DisconnectAsync(CancellationToken cancellationToken)
@@ -126,20 +124,7 @@ namespace MQTTnet.Extensions.WebSocket4Net
                 _webSocket.Close();
             }
             
-            return CompletedTask.Instance;
+            return Task.FromResult(0);
-        }
-
-        public void Dispose()
-        {
-            if (_webSocket == null)
-            {
-                return;
-            }
-
-            _webSocket.DataReceived -= OnDataReceived;
-            _webSocket.Error -= OnError;
-            _webSocket.Dispose();
-            _webSocket = null;
         }
 
         public Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
@@ -169,10 +154,36 @@ namespace MQTTnet.Extensions.WebSocket4Net
             return Task.FromResult(readBytes);
         }
 
-        public Task WriteAsync(ArraySegment<byte> buffer, bool isEndOfPacket, CancellationToken cancellationToken)
+        public Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
         {
-            _webSocket.Send(buffer.Array, buffer.Offset, buffer.Count);
+            _webSocket.Send(buffer, offset, count);
-            return CompletedTask.Instance;
+            return Task.FromResult(0);
+        }
+
+        public void Dispose()
+        {
+            if (_webSocket == null)
+            {
+                return;
+            }
+
+            _webSocket.DataReceived -= OnDataReceived;
+            _webSocket.Error -= OnError;
+            _webSocket.Dispose();
+            _webSocket = null;
+        }
+
+        static void OnError(object sender, ErrorEventArgs e)
+        {
+            System.Diagnostics.Debug.Write(e.Exception.ToString());
+        }
+
+        void OnDataReceived(object sender, DataReceivedEventArgs e)
+        {
+            foreach (var @byte in e.Data)
+            {
+                _receiveBuffer.Add(@byte);
+            }
         }
 
         async Task ConnectInternalAsync(CancellationToken cancellationToken)
@@ -180,45 +191,39 @@ namespace MQTTnet.Extensions.WebSocket4Net
             _webSocket.Error += OnError;
             _webSocket.DataReceived += OnDataReceived;
 
-            var promise = new AsyncTaskCompletionSource<bool>();
+            var taskCompletionSource = new TaskCompletionSource<Exception>();
 
             void ErrorHandler(object sender, ErrorEventArgs e)
             {
-                promise.TrySetException(e.Exception);
+                taskCompletionSource.TrySetResult(e.Exception);
             }
 
-            void OpenedHandler(object sender, EventArgs e)
+            void SuccessHandler(object sender, EventArgs e)
             {
-                promise.TrySetResult(true);
+                taskCompletionSource.TrySetResult(null);
-            }
-
-            void ClosedHandler(object sender, EventArgs e)
-            {
-                promise.TrySetException(new MqttCommunicationException("Connection closed."));
             }
 
             try
             {
-                _webSocket.Opened += OpenedHandler;
+                _webSocket.Opened += SuccessHandler;
-                _webSocket.Closed += ClosedHandler;
                 _webSocket.Error += ErrorHandler;
 
-                using (var timeout = new CancellationTokenSource(_clientOptions.Timeout))
+#pragma warning disable AsyncFixer02 // Long-running or blocking operations inside an async method
-                using (var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(timeout.Token, cancellationToken))
+                _webSocket.Open();
+#pragma warning restore AsyncFixer02 // Long-running or blocking operations inside an async method
+
+                using (var timeoutCts = new CancellationTokenSource(_clientOptions.Timeout))
+                using (var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(timeoutCts.Token, cancellationToken))
                 {
-                    using (linkedCts.Token.Register(() => promise.TrySetCanceled()))
+                    using (linkedCts.Token.Register(() => taskCompletionSource.TrySetCanceled()))
                     {
                         try
                         {
-                            // OpenAsync does basically the same but without support for a cancellation token.
+                            await taskCompletionSource.Task.ConfigureAwait(false);
-                            // So we do it on our own!
-                            _webSocket.Open();
-
-                            await promise.Task.ConfigureAwait(false);
                         }
                         catch (Exception exception)
                         {
-                            var timeoutReached = timeout.IsCancellationRequested && !cancellationToken.IsCancellationRequested;
+                            var timeoutReached = timeoutCts.IsCancellationRequested && !cancellationToken.IsCancellationRequested;
                             if (timeoutReached)
                             {
                                 throw new MqttCommunicationTimedOutException(exception);
@@ -245,23 +250,9 @@ namespace MQTTnet.Extensions.WebSocket4Net
             }
             finally
             {
-                _webSocket.Opened -= OpenedHandler;
+                _webSocket.Opened -= SuccessHandler;
-                _webSocket.Closed -= ClosedHandler;
                 _webSocket.Error -= ErrorHandler;
             }
         }
-
-        void OnDataReceived(object sender, DataReceivedEventArgs e)
-        {
-            foreach (var @byte in e.Data)
-            {
-                _receiveBuffer.Add(@byte);
-            }
-        }
-
-        static void OnError(object sender, ErrorEventArgs e)
-        {
-            Debug.Write(e.Exception.ToString());
-        }
     }
 }

Source/MQTTnet.Extensions.WebSocket4Net/WebSocket4NetMqttClientAdapterFactory.cs

@@ -2,12 +2,12 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using MQTTnet.Adapter;
-using MQTTnet.Client;
-using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
 using MQTTnet.Implementations;
+using System;
+using MQTTnet.Client;
+using MQTTnet.Diagnostics;
 
 namespace MQTTnet.Extensions.WebSocket4Net
 {
@@ -15,10 +15,7 @@ namespace MQTTnet.Extensions.WebSocket4Net
     {
         public IMqttChannelAdapter CreateClientAdapter(MqttClientOptions options, MqttPacketInspector packetInspector, IMqttNetLogger logger)
         {
-            if (options == null)
+            if (options == null) throw new ArgumentNullException(nameof(options));
-            {
-                throw new ArgumentNullException(nameof(options));
-            }
 
             switch (options.ChannelOptions)
             {
@@ -26,7 +23,7 @@ namespace MQTTnet.Extensions.WebSocket4Net
                 {
                     return new MqttChannelAdapter(
                         new MqttTcpChannel(options),
-                        new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttBufferWriter(options.WriterBufferSize, options.WriterBufferSizeMax)),
+                        new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttBufferWriter(4096, 65535)),
                         packetInspector,
                         logger);
                 }
@@ -35,15 +32,15 @@ namespace MQTTnet.Extensions.WebSocket4Net
                 {
                     return new MqttChannelAdapter(
                         new WebSocket4NetMqttChannel(options, webSocketOptions),
-                        new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttBufferWriter(options.WriterBufferSize, options.WriterBufferSizeMax)),
+                        new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttBufferWriter(4068, 65535)), 
                         packetInspector,
                         logger);
                 }
 
                 default:
-                {
+                    {
-                    throw new NotSupportedException();
+                        throw new NotSupportedException();
-                }
+                    }
             }
         }
     }

Source/MQTTnet.TestApp/AsyncLockTest.cs

@@ -1,28 +0,0 @@
-// 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.
-
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Internal;
-
-namespace MQTTnet.TestApp
-{
-    public sealed class AsyncLockTest
-    {
-        public async Task Run()
-        {
-            var asyncLock = new AsyncLock();
-
-            using (var cancellationToken = new CancellationTokenSource())
-            {
-                for (var i = 0; i < 100000; i++)
-                {
-                    using (await asyncLock.EnterAsync(cancellationToken.Token).ConfigureAwait(false))
-                    {
-                    }
-                } 
-            }
-        }
-    }
-}

Source/MQTTnet.TestApp/ClientTest.cs

@@ -7,7 +7,7 @@ using System;
 using System.Text;
 using System.Threading.Tasks;
 using MQTTnet.Diagnostics;
-using MQTTnet.Internal;
+using MQTTnet.Implementations;
 using MQTTnet.Protocol;
 
 namespace MQTTnet.TestApp
@@ -40,7 +40,7 @@ namespace MQTTnet.TestApp
                     Console.WriteLine($"+ Retain = {e.ApplicationMessage.Retain}");
                     Console.WriteLine();
                     
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 client.ConnectedAsync += async e =>

Source/MQTTnet.TestApp/MQTTnet.TestApp.csproj

@@ -9,11 +9,12 @@
         <EnableNETAnalyzers>false</EnableNETAnalyzers>
         <EnforceCodeStyleInBuild>false</EnforceCodeStyleInBuild>
         <DisableImplicitAspNetCoreAnalyzers>true</DisableImplicitAspNetCoreAnalyzers>
-        <NoWarn>1591;NETSDK1138</NoWarn>
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="Newtonsoft.Json" Version="13.0.2" />
+        <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
+        <PackageReference Include="Microsoft.CodeAnalysis.Compilers" Version="4.0.1" />
+        <PackageReference Include="Microsoft.Net.Compilers" Version="4.0.1" />
     </ItemGroup>
 
     <ItemGroup>

Source/MQTTnet.TestApp/ManagedClientTest.cs

@@ -9,7 +9,7 @@ using Newtonsoft.Json;
 using System.Collections.Generic;
 using MQTTnet.Client;
 using MQTTnet.Extensions.ManagedClient;
-using MQTTnet.Internal;
+using MQTTnet.Implementations;
 using MQTTnet.Protocol;
 
 namespace MQTTnet.TestApp
@@ -42,7 +42,7 @@ namespace MQTTnet.TestApp
                 managedClient.ApplicationMessageReceivedAsync += e =>
                 {
                     Console.WriteLine(">> RECEIVED: " + e.ApplicationMessage.Topic);
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await managedClient.StartAsync(options);
@@ -85,7 +85,7 @@ namespace MQTTnet.TestApp
             public Task SaveQueuedMessagesAsync(IList<ManagedMqttApplicationMessage> messages)
             {
                 File.WriteAllText(Filename, JsonConvert.SerializeObject(messages));
-                return CompletedTask.Instance;
+                return Task.FromResult(0);
             }
 
             public Task<IList<ManagedMqttApplicationMessage>> LoadQueuedMessagesAsync()

Source/MQTTnet.TestApp/MessageThroughputTest.cs

@@ -5,7 +5,6 @@ using System;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Linq;
-using MQTTnet.Internal;
 
 namespace MQTTnet.TestApp
 {
@@ -125,7 +124,7 @@ namespace MQTTnet.TestApp
             {
                 _cancellationTokenSource.Cancel();
             }
-            return CompletedTask.Instance;
+            return Implementations.PlatformAbstractionLayer.CompletedTask;
         }
 
         public async Task Cleanup()

Source/MQTTnet.TestApp/Program.cs

@@ -28,7 +28,6 @@ namespace MQTTnet.TestApp
             Console.WriteLine("c = Start QoS 0 benchmark");
             Console.WriteLine("d = Start server with logging");
             Console.WriteLine("e = Start Message Throughput Test");
-            Console.WriteLine("f = Start AsyncLock Test");
 
             var pressedKey = Console.ReadKey(true);
             if (pressedKey.KeyChar == '1')
@@ -89,10 +88,6 @@ namespace MQTTnet.TestApp
             {
                 Task.Run(new MessageThroughputTest().Run);
             }
-            else if (pressedKey.KeyChar == 'f')
-            {
-                Task.Run(new AsyncLockTest().Run);
-            }
 
             Thread.Sleep(Timeout.Infinite);
         }

Source/MQTTnet.TestApp/PublicBrokerTest.cs

@@ -2,14 +2,13 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using MQTTnet.Client;
 using System;
 using System.Security.Authentication;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Client;
-using MQTTnet.Extensions.WebSocket4Net;
 using MQTTnet.Formatter;
-using MQTTnet.Internal;
+using MQTTnet.Implementations;
 using MQTTnet.Protocol;
 
 namespace MQTTnet.TestApp
@@ -18,6 +17,10 @@ namespace MQTTnet.TestApp
     {
         public static async Task RunAsync()
         {
+            // MqttNetConsoleLogger.ForwardToConsole();
+
+            // For most of these connections to work, set output target to Net5.0.            
+
 #if NET5_0_OR_GREATER
             // TLS13 is only available in Net5.0
             var unsafeTls13 = new MqttClientOptionsBuilderTlsParameters
@@ -28,6 +31,7 @@ namespace MQTTnet.TestApp
                 CertificateValidationHandler = w => true
             };
 #endif
+
             // Also defining TLS12 for servers that don't seem no to support TLS13.
             var unsafeTls12 = new MqttClientOptionsBuilderTlsParameters
             {
@@ -38,37 +42,33 @@ namespace MQTTnet.TestApp
             };
 
             // mqtt.eclipseprojects.io
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("mqtt.eclipseprojects.io TCP",
-                "mqtt.eclipseprojects.io TCP",
+                    new MqttClientOptionsBuilder().WithTcpServer("mqtt.eclipseprojects.io", 1883)
-                new MqttClientOptionsBuilder().WithTcpServer("mqtt.eclipseprojects.io", 1883).WithProtocolVersion(MqttProtocolVersion.V311).Build());
+                        .WithProtocolVersion(MqttProtocolVersion.V311).Build());
 
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("mqtt.eclipseprojects.io WS",
-                "mqtt.eclipseprojects.io WS",
+                new MqttClientOptionsBuilder().WithWebSocketServer("mqtt.eclipseprojects.io:80/mqtt")
-                new MqttClientOptionsBuilder().WithWebSocketServer("mqtt.eclipseprojects.io:80/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).Build());
+                    .WithProtocolVersion(MqttProtocolVersion.V311).Build());
 
 #if NET5_0_OR_GREATER
             await ExecuteTestAsync("mqtt.eclipseprojects.io WS TLS13",
                 new MqttClientOptionsBuilder().WithWebSocketServer("mqtt.eclipseprojects.io:443/mqtt")
                     .WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls13).Build());
-            
-            await ExecuteTestAsync("mqtt.eclipseprojects.io WS TLS13 (WebSocket4Net)",
-                new MqttClientOptionsBuilder().WithWebSocketServer("mqtt.eclipseprojects.io:443/mqtt")
-                    .WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls13).Build(),
-                    true);
 #endif
 
             // test.mosquitto.org
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("test.mosquitto.org TCP",
-                "test.mosquitto.org TCP",
+                new MqttClientOptionsBuilder().WithTcpServer("test.mosquitto.org", 1883)
-                new MqttClientOptionsBuilder().WithTcpServer("test.mosquitto.org", 1883).WithProtocolVersion(MqttProtocolVersion.V311).Build());
+                    .WithProtocolVersion(MqttProtocolVersion.V311).Build());
 
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("test.mosquitto.org TCP - Authenticated",
-                "test.mosquitto.org TCP - Authenticated",
+                new MqttClientOptionsBuilder().WithTcpServer("test.mosquitto.org", 1884)
-                new MqttClientOptionsBuilder().WithTcpServer("test.mosquitto.org", 1884).WithCredentials("rw", "readwrite").WithProtocolVersion(MqttProtocolVersion.V311).Build());
+                    .WithCredentials("rw", "readwrite")
+                    .WithProtocolVersion(MqttProtocolVersion.V311).Build());
 
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("test.mosquitto.org TCP TLS12",
-                "test.mosquitto.org TCP TLS12",
+                new MqttClientOptionsBuilder().WithTcpServer("test.mosquitto.org", 8883)
-                new MqttClientOptionsBuilder().WithTcpServer("test.mosquitto.org", 8883).WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build());
+                    .WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build());
 
 #if NET5_0_OR_GREATER
             await ExecuteTestAsync("test.mosquitto.org TCP TLS13",
@@ -76,40 +76,27 @@ namespace MQTTnet.TestApp
                     .WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls13).Build());
 #endif
 
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("test.mosquitto.org TCP TLS12 - Authenticated",
-                "test.mosquitto.org TCP TLS12 - Authenticated",
                 new MqttClientOptionsBuilder().WithTcpServer("test.mosquitto.org", 8885)
                     .WithCredentials("rw", "readwrite")
-                    .WithProtocolVersion(MqttProtocolVersion.V311)
+                    .WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build());
-                    .WithTls(unsafeTls12)
-                    .Build());
 
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("test.mosquitto.org WS",
-                "test.mosquitto.org WS",
+                new MqttClientOptionsBuilder().WithWebSocketServer("test.mosquitto.org:8080/mqtt")
-                new MqttClientOptionsBuilder().WithWebSocketServer("test.mosquitto.org:8080/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).Build());
+                    .WithProtocolVersion(MqttProtocolVersion.V311).Build());
 
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("test.mosquitto.org WS TLS12",
-                "test.mosquitto.org WS (WebSocket4Net)",
+                new MqttClientOptionsBuilder().WithWebSocketServer("test.mosquitto.org:8081/mqtt")
-                new MqttClientOptionsBuilder().WithWebSocketServer("test.mosquitto.org:8080/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).Build(),
+                    .WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build());
-                true);
-
-            await ExecuteTestAsync(
-                "test.mosquitto.org WS TLS12",
-                new MqttClientOptionsBuilder().WithWebSocketServer("test.mosquitto.org:8081/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build());
-
-            // await ExecuteTestAsync(
-            //     "test.mosquitto.org WS TLS12 (WebSocket4Net)",
-            //     new MqttClientOptionsBuilder().WithWebSocketServer("test.mosquitto.org:8081/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build(),
-            //     true);
 
             // broker.emqx.io
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("broker.emqx.io TCP",
-                "broker.emqx.io TCP",
+                new MqttClientOptionsBuilder().WithTcpServer("broker.emqx.io", 1883)
-                new MqttClientOptionsBuilder().WithTcpServer("broker.emqx.io", 1883).WithProtocolVersion(MqttProtocolVersion.V311).Build());
+                     .WithProtocolVersion(MqttProtocolVersion.V311).Build());
 
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("broker.emqx.io TCP TLS12",
-                "broker.emqx.io TCP TLS12",
+                new MqttClientOptionsBuilder().WithTcpServer("broker.emqx.io", 8883)
-                new MqttClientOptionsBuilder().WithTcpServer("broker.emqx.io", 8883).WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build());
+                    .WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build());
 
 #if NET5_0_OR_GREATER
             await ExecuteTestAsync("broker.emqx.io TCP TLS13",
@@ -117,37 +104,23 @@ namespace MQTTnet.TestApp
                     .WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls13).Build());
 #endif
 
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("broker.emqx.io WS",
-                "broker.emqx.io WS",
+                new MqttClientOptionsBuilder().WithWebSocketServer("broker.emqx.io:8083/mqtt")
-                new MqttClientOptionsBuilder().WithWebSocketServer("broker.emqx.io:8083/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).Build());
+                    .WithProtocolVersion(MqttProtocolVersion.V311).Build());
 
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("broker.emqx.io WS TLS12",
-                "broker.emqx.io WS (WebSocket4Net)",
+                new MqttClientOptionsBuilder().WithWebSocketServer("broker.emqx.io:8084/mqtt")
-                new MqttClientOptionsBuilder().WithWebSocketServer("broker.emqx.io:8084/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).Build(),
+                    .WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build());
-                true);
 
-            await ExecuteTestAsync(
-                "broker.emqx.io WS TLS12",
-                new MqttClientOptionsBuilder().WithWebSocketServer("broker.emqx.io:8084/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build());
-
-            await ExecuteTestAsync(
-                "broker.emqx.io WS TLS12 (WebSocket4Net)",
-                new MqttClientOptionsBuilder().WithWebSocketServer("broker.emqx.io:8084/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).WithTls(unsafeTls12).Build(),
-                true);
 
             // broker.hivemq.com
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("broker.hivemq.com TCP",
-                "broker.hivemq.com TCP",
+                new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com", 1883)
-                new MqttClientOptionsBuilder().WithTcpServer("broker.hivemq.com", 1883).WithProtocolVersion(MqttProtocolVersion.V311).Build());
+                    .WithProtocolVersion(MqttProtocolVersion.V311).Build());
 
-            await ExecuteTestAsync(
+            await ExecuteTestAsync("broker.hivemq.com WS",
-                "broker.hivemq.com WS",
+                new MqttClientOptionsBuilder().WithWebSocketServer("broker.hivemq.com:8000/mqtt")
-                new MqttClientOptionsBuilder().WithWebSocketServer("broker.hivemq.com:8000/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).Build());
+                    .WithProtocolVersion(MqttProtocolVersion.V311).Build());
-
-            await ExecuteTestAsync(
-                "broker.hivemq.com WS (WebSocket4Net)",
-                new MqttClientOptionsBuilder().WithWebSocketServer("broker.hivemq.com:8000/mqtt").WithProtocolVersion(MqttProtocolVersion.V311).Build(),
-                true);
 
             // mqtt.swifitch.cz: Does not seem to operate any more
 
@@ -157,43 +130,36 @@ namespace MQTTnet.TestApp
             Console.ReadLine();
         }
 
-        static async Task ExecuteTestAsync(string name, MqttClientOptions options, bool useWebSocket4Net = false)
+        static async Task ExecuteTestAsync(string name, MqttClientOptions options)
         {
             try
             {
                 Write("Testing '" + name + "'... ", ConsoleColor.Gray);
-
                 var factory = new MqttFactory();
-                if (useWebSocket4Net)
+                //factory.UseWebSocket4Net();
+                var client = factory.CreateMqttClient();
+                var topic = Guid.NewGuid().ToString();
+
+                MqttApplicationMessage receivedMessage = null;
+                client.ApplicationMessageReceivedAsync += e =>
                 {
-                    factory.UseWebSocket4Net();
+                    receivedMessage = e.ApplicationMessage;
+                    return PlatformAbstractionLayer.CompletedTask;
+                };
+
+                await client.ConnectAsync(options);
+                await client.SubscribeAsync(topic, MqttQualityOfServiceLevel.AtLeastOnce);
+                await client.PublishStringAsync(topic, "Hello_World", MqttQualityOfServiceLevel.AtLeastOnce);
+
+                SpinWait.SpinUntil(() => receivedMessage != null, 5000);
+
+                if (receivedMessage?.Topic != topic || receivedMessage?.ConvertPayloadToString() != "Hello_World")
+                {
+                    throw new Exception("Message invalid.");
                 }
 
-                using (var client = factory.CreateMqttClient())
+                await client.UnsubscribeAsync(topic);
-                {
+                await client.DisconnectAsync();
-                    MqttApplicationMessage receivedMessage = null;
-                    client.ApplicationMessageReceivedAsync += e =>
-                    {
-                        receivedMessage = e.ApplicationMessage;
-                        return CompletedTask.Instance;
-                    };
-
-                    await client.ConnectAsync(options).ConfigureAwait(false);
-
-                    var topic = Guid.NewGuid().ToString();
-                    await client.SubscribeAsync(topic, MqttQualityOfServiceLevel.AtLeastOnce).ConfigureAwait(false);
-                    await client.PublishStringAsync(topic, "Hello_World", MqttQualityOfServiceLevel.AtLeastOnce).ConfigureAwait(false);
-
-                    SpinWait.SpinUntil(() => receivedMessage != null, 5000);
-
-                    if (receivedMessage?.Topic != topic || receivedMessage?.ConvertPayloadToString() != "Hello_World")
-                    {
-                        throw new Exception("Message invalid.");
-                    }
-
-                    await client.UnsubscribeAsync(topic).ConfigureAwait(false);
-                    await client.DisconnectAsync().ConfigureAwait(false);
-                }
 
                 Write("[OK]\n", ConsoleColor.Green);
             }
@@ -208,5 +174,6 @@ namespace MQTTnet.TestApp
             Console.ForegroundColor = color;
             Console.Write(message);
         }
+
     }
 }

Source/MQTTnet.TestApp/ServerTest.cs

@@ -4,11 +4,13 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Text;
 using System.Threading.Tasks;
 using MQTTnet.Diagnostics;
-using MQTTnet.Internal;
+using MQTTnet.Extensions.ManagedClient;
+using MQTTnet.Implementations;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
 using Newtonsoft.Json;
@@ -67,13 +69,13 @@ namespace MQTTnet.TestApp
                     }
 
                     File.WriteAllText(Filename, JsonConvert.SerializeObject(e.StoredRetainedMessages));
-                    return CompletedTask.Instance;
+                    return Task.FromResult(0);
                 };
                 
                 mqttServer.RetainedMessagesClearedAsync += e =>
                 {
                     File.Delete(Filename);
-                    return CompletedTask.Instance;
+                    return Task.FromResult(0);
                 };
                 
                 mqttServer.LoadingRetainedMessageAsync += e =>
@@ -91,7 +93,7 @@ namespace MQTTnet.TestApp
 
                     e.LoadedRetainedMessages = retainedMessages;
 
-                    return CompletedTask.Instance;
+                    return Task.FromResult(0);
                 };
 
                 mqttServer.InterceptingPublishAsync += e =>
@@ -109,7 +111,7 @@ namespace MQTTnet.TestApp
                         e.CloseConnection = true;
                     }
 
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
                 
                 mqttServer.ValidatingConnectionAsync += e =>
@@ -122,7 +124,7 @@ namespace MQTTnet.TestApp
                         }
                     }
 
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 mqttServer.InterceptingSubscriptionAsync += e =>
@@ -138,7 +140,7 @@ namespace MQTTnet.TestApp
                         e.CloseConnection = true;
                     }
 
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
                 
                 mqttServer.InterceptingPublishAsync += e =>
@@ -147,7 +149,7 @@ namespace MQTTnet.TestApp
                         $"'{e.ClientId}' reported '{e.ApplicationMessage.Topic}' > '{Encoding.UTF8.GetString(e.ApplicationMessage.Payload ?? new byte[0])}'",
                         ConsoleColor.Magenta);
                     
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 //options.ApplicationMessageInterceptor = c =>
@@ -175,7 +177,7 @@ namespace MQTTnet.TestApp
                 mqttServer.ClientConnectedAsync += e =>
                 {
                     Console.Write("Client disconnected event fired.");
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await mqttServer.StartAsync();

Source/MQTTnet.Tests/Client/LowLevelMqttClient_Tests.cs

@@ -80,8 +80,6 @@ namespace MQTTnet.Tests.Client
         {
             using (var testEnvironment = CreateTestEnvironment())
             {
-                testEnvironment.IgnoreServerLogErrors = true;
-
                 testEnvironment.ServerPort = 8364;
                 var server = await testEnvironment.StartServer();
 
@@ -118,8 +116,6 @@ namespace MQTTnet.Tests.Client
         {
             using (var testEnvironment = CreateTestEnvironment())
             {
-                testEnvironment.IgnoreServerLogErrors = true;
-
                 var server = await testEnvironment.StartServer();
 
                 using (var lowLevelClient = testEnvironment.CreateLowLevelClient())

Source/MQTTnet.Tests/Client/ManagedMqttClient_Tests.cs

@@ -11,78 +11,18 @@ using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
 using MQTTnet.Diagnostics;
 using MQTTnet.Extensions.ManagedClient;
-using MQTTnet.Formatter;
+using MQTTnet.Implementations;
 using MQTTnet.Internal;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
 using MQTTnet.Tests.Mockups;
+using MqttClient = MQTTnet.Client.MqttClient;
 
 namespace MQTTnet.Tests.Client
 {
     [TestClass]
     public sealed class ManagedMqttClient_Tests : BaseTestClass
     {
-        [TestMethod]
-        public async Task Receive_While_Not_Cleanly_Disconnected()
-        {
-            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
-            {
-                await testEnvironment.StartServer(o => o.WithPersistentSessions());
-
-                var senderClient = await testEnvironment.ConnectClient();
-
-                // Prepare managed client.
-                var managedClient = testEnvironment.Factory.CreateManagedMqttClient();
-                await managedClient.SubscribeAsync("#");
-                var receivedMessages = testEnvironment.CreateApplicationMessageHandler(managedClient);
-                
-                var managedClientOptions = new ManagedMqttClientOptions
-                {
-                    ClientOptions = testEnvironment.Factory.CreateClientOptionsBuilder()
-                        .WithTcpServer("127.0.0.1", testEnvironment.ServerPort)
-                        .WithClientId(nameof(Receive_While_Not_Cleanly_Disconnected) + "_managed")
-                        .WithCleanSession(false)
-                        .Build()
-                };
-
-                await managedClient.StartAsync(managedClientOptions);
-                await LongTestDelay();
-                await LongTestDelay();
-                
-                // Send test data.
-                await senderClient.PublishStringAsync("topic1");
-                await LongTestDelay();
-                await LongTestDelay();
-                
-                receivedMessages.AssertReceivedCountEquals(1);
-
-                // Stop the managed client but keep session at server (not clean disconnect required).
-                await managedClient.StopAsync(false);
-                await LongTestDelay();
-                
-                // Send new messages in the meantime.
-                await senderClient.PublishStringAsync("topic2", qualityOfServiceLevel: MqttQualityOfServiceLevel.ExactlyOnce);
-                await LongTestDelay();
-                
-                // Start the managed client, it should receive the new message.
-                await managedClient.StartAsync(managedClientOptions);
-                await LongTestDelay();
-                
-                receivedMessages.AssertReceivedCountEquals(2);
-                
-                // Stop and start again, no new message should be received.
-                for (var i = 0; i < 3; i++)
-                {
-                    await managedClient.StopAsync(false);
-                    await LongTestDelay();
-                    await managedClient.StartAsync(managedClientOptions);
-                    await LongTestDelay();
-                }
-
-                receivedMessages.AssertReceivedCountEquals(2);
-            }
-        }
-
         [TestMethod]
         public async Task Connect_To_Invalid_Server()
         {
@@ -95,10 +35,11 @@ namespace MQTTnet.Tests.Client
                 var managedClient = testEnvironment.Factory.CreateManagedMqttClient(mqttClient);
 
                 ConnectingFailedEventArgs connectingFailedEventArgs = null;
+
                 managedClient.ConnectingFailedAsync += args =>
                 {
                     connectingFailedEventArgs = args;
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await managedClient.StartAsync(
@@ -176,7 +117,7 @@ namespace MQTTnet.Tests.Client
                 receivingClient.ApplicationMessageReceivedAsync += e =>
                 {
                     Interlocked.Increment(ref receivedMessagesCount);
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await receivingClient.SubscribeAsync("My/last/will");
@@ -331,10 +272,16 @@ namespace MQTTnet.Tests.Client
                 await testEnvironment.StartServer().ConfigureAwait(false);
 
                 var sendingClient = await testEnvironment.ConnectClient().ConfigureAwait(false);
-                await sendingClient.PublishStringAsync("topic", "A", retain: true);
+                await sendingClient.PublishAsync(
+                    new MqttApplicationMessage
+                    {
+                        Topic = "topic",
+                        Payload = new byte[] { 1 },
+                        Retain = true
+                    });
 
                 // Wait a bit for the retained message to be available
-                await LongTestDelay();
+                await Task.Delay(1000);
 
                 await sendingClient.DisconnectAsync();
 
@@ -343,26 +290,28 @@ namespace MQTTnet.Tests.Client
                 var clientOptions = new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort);
 
                 var receivedManagedMessages = new List<MqttApplicationMessage>();
-                
+                var managedClient = new ManagedMqttClient(testEnvironment.CreateClient(), new MqttNetEventLogger());
-                var managedClient = testEnvironment.Factory.CreateManagedMqttClient(testEnvironment.CreateClient());
                 managedClient.ApplicationMessageReceivedAsync += e =>
                 {
                     receivedManagedMessages.Add(e.ApplicationMessage);
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await managedClient.SubscribeAsync("topic");
 
-                await managedClient.StartAsync(new ManagedMqttClientOptionsBuilder().WithClientOptions(clientOptions).WithAutoReconnectDelay(TimeSpan.FromSeconds(0.5)).Build());
+                await managedClient.StartAsync(new ManagedMqttClientOptionsBuilder().WithClientOptions(clientOptions).WithAutoReconnectDelay(TimeSpan.FromSeconds(1)).Build());
-                await LongTestDelay();
+
+                await Task.Delay(1000);
 
                 Assert.AreEqual(1, receivedManagedMessages.Count);
 
                 await managedClient.StopAsync();
-                await LongTestDelay();
 
-                await managedClient.StartAsync(new ManagedMqttClientOptionsBuilder().WithClientOptions(clientOptions).WithAutoReconnectDelay(TimeSpan.FromSeconds(0.5)).Build());
+                await Task.Delay(500);
-                await LongTestDelay();
+
+                await managedClient.StartAsync(new ManagedMqttClientOptionsBuilder().WithClientOptions(clientOptions).WithAutoReconnectDelay(TimeSpan.FromSeconds(1)).Build());
+
+                await Task.Delay(1000);
 
                 // After reconnect and then some delay, the retained message must not be received,
                 // showing that the subscriptions were cleared
@@ -370,8 +319,7 @@ namespace MQTTnet.Tests.Client
 
                 // Make sure that it gets received after subscribing again.
                 await managedClient.SubscribeAsync("topic");
-                await LongTestDelay();
+                await Task.Delay(500);
-                
                 Assert.AreEqual(2, receivedManagedMessages.Count);
             }
         }
@@ -480,7 +428,7 @@ namespace MQTTnet.Tests.Client
             managedClient.ConnectedAsync += e =>
             {
                 connected.TrySetResult(true);
-                return CompletedTask.Instance;
+                return PlatformAbstractionLayer.CompletedTask;
             };
 
             return connected.Task;
@@ -509,7 +457,7 @@ namespace MQTTnet.Tests.Client
                     result.TrySetResult(receivedMessages);
                 }
 
-                return CompletedTask.Instance;
+                return PlatformAbstractionLayer.CompletedTask;
             };
 
             return result.Task;
@@ -538,7 +486,7 @@ namespace MQTTnet.Tests.Client
         public Task SaveQueuedMessagesAsync(IList<ManagedMqttApplicationMessage> messages)
         {
             _messages = messages;
-            return CompletedTask.Instance;
+            return Task.FromResult(0);
         }
     }
 }

Source/MQTTnet.Tests/Client/MqttClient_Tests.cs

@@ -14,17 +14,15 @@ using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
-using MQTTnet.Internal;
+using MQTTnet.Implementations;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
 using MQTTnet.Tests.Mockups;
 
-// ReSharper disable InconsistentNaming
-
 namespace MQTTnet.Tests.Client
 {
     [TestClass]
-    public sealed class MqttClient_Tests : BaseTestClass
+    public sealed class Client_Tests : BaseTestClass
     {
         [DataTestMethod]
         [DataRow(MqttQualityOfServiceLevel.ExactlyOnce)]
@@ -58,7 +56,7 @@ namespace MQTTnet.Tests.Client
                     }
 
                     _ = InvokeInternal();
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 var publishes = Task.WhenAll(publisher.PublishStringAsync("a", null, qos), publisher.PublishStringAsync("b", null, qos));
@@ -109,7 +107,7 @@ namespace MQTTnet.Tests.Client
                     client.DisconnectedAsync += args =>
                     {
                         disconnectHandlerCalled = true;
-                        return CompletedTask.Instance;
+                        return PlatformAbstractionLayer.CompletedTask;
                     };
 
                     await client.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("1.2.3.4").Build());
@@ -123,7 +121,7 @@ namespace MQTTnet.Tests.Client
                     //Assert.IsInstanceOfType(exception.InnerException, typeof(SocketException));
                 }
 
-                await LongTestDelay(); // disconnected handler is called async
+                await Task.Delay(100); // disconnected handler is called async
                 Assert.IsTrue(disconnectHandlerCalled);
             }
         }
@@ -138,7 +136,7 @@ namespace MQTTnet.Tests.Client
                 client.DisconnectedAsync += e =>
                 {
                     ex = e.Exception;
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 try
@@ -147,7 +145,6 @@ namespace MQTTnet.Tests.Client
                 }
                 catch
                 {
-                    // Ignore errors.
                 }
 
                 await Task.Delay(500);
@@ -170,7 +167,7 @@ namespace MQTTnet.Tests.Client
                 server.InterceptingPublishAsync += c =>
                 {
                     i++;
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await client.SendAsync(
@@ -211,7 +208,7 @@ namespace MQTTnet.Tests.Client
                 client.DisconnectedAsync += e =>
                 {
                     handlerFired = true;
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await server.StopAsync();
@@ -242,10 +239,10 @@ namespace MQTTnet.Tests.Client
 
                 for (var i = 0; i < 98; i++)
                 {
-                    Assert.IsFalse(clients[i].TryPingAsync().GetAwaiter().GetResult(), $"clients[{i}] is not connected");
+                    Assert.IsFalse(clients[i].IsConnected, $"clients[{i}] is not connected");
                 }
 
-                Assert.IsTrue(clients[99].TryPingAsync().GetAwaiter().GetResult());
+                Assert.IsTrue(clients[99].IsConnected);
 
                 Assert.AreEqual(1, clientStatus.Count);
                 Assert.AreEqual(1, sessionStatus.Count);
@@ -255,7 +252,7 @@ namespace MQTTnet.Tests.Client
                 receiveClient.ApplicationMessageReceivedAsync += e =>
                 {
                     receivedPayload = e.ApplicationMessage.ConvertPayloadToString();
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await receiveClient.SubscribeAsync("x");
@@ -313,7 +310,7 @@ namespace MQTTnet.Tests.Client
                 receiver.ApplicationMessageReceivedAsync += e =>
                 {
                     receivedMessage = e.ApplicationMessage;
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await sender.PublishAsync(message.Build(), CancellationToken.None);
@@ -335,7 +332,7 @@ namespace MQTTnet.Tests.Client
 
                 var client = await testEnvironment.ConnectClient();
 
-                Assert.IsTrue(client.TryPingAsync().GetAwaiter().GetResult());
+                Assert.IsTrue(client.IsConnected);
             }
         }
 
@@ -346,11 +343,11 @@ namespace MQTTnet.Tests.Client
             {
                 await testEnvironment.StartServer();
                 var client = await testEnvironment.ConnectClient();
-                Assert.IsTrue(client.TryPingAsync().GetAwaiter().GetResult());
+                Assert.IsTrue(client.IsConnected);
 
                 await client.DisconnectAsync();
 
-                Assert.IsFalse(client.TryPingAsync().GetAwaiter().GetResult());
+                Assert.IsFalse(client.IsConnected);
             }
         }
 
@@ -456,7 +453,7 @@ namespace MQTTnet.Tests.Client
                         receivedValues.Add(value);
                     }
 
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 }
 
                 client1.ApplicationMessageReceivedAsync += Handler1;
@@ -534,7 +531,7 @@ namespace MQTTnet.Tests.Client
                 client2.ApplicationMessageReceivedAsync += e =>
                 {
                     client2TopicResults.Add(Encoding.UTF8.GetString(e.ApplicationMessage.Payload));
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await client2.SubscribeAsync(client2Topic);
@@ -569,7 +566,7 @@ namespace MQTTnet.Tests.Client
                         receivedMessages.Add(e.ApplicationMessage);
                     }
 
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await client1.SubscribeAsync("a");
@@ -594,17 +591,17 @@ namespace MQTTnet.Tests.Client
                 var client = await testEnvironment.ConnectClient();
 
                 await Task.Delay(500);
-                Assert.IsTrue(await client.TryPingAsync());
+                Assert.IsTrue(client.IsConnected);
 
                 await server.StopAsync();
                 await Task.Delay(500);
-                Assert.IsFalse(await client.TryPingAsync());
+                Assert.IsFalse(client.IsConnected);
 
                 await server.StartAsync();
                 await Task.Delay(500);
 
                 await client.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).Build());
-                Assert.IsTrue(await client.TryPingAsync());
+                Assert.IsTrue(client.IsConnected);
             }
         }
 
@@ -640,7 +637,6 @@ namespace MQTTnet.Tests.Client
                 }
                 catch
                 {
-                    // Ignore errors.
                 }
 
                 SpinWait.SpinUntil(() => tries >= maxTries, 10000);
@@ -660,11 +656,11 @@ namespace MQTTnet.Tests.Client
                 var client = await testEnvironment.ConnectClient();
 
                 await Task.Delay(500);
-                Assert.IsTrue(client.TryPingAsync().GetAwaiter().GetResult());
+                Assert.IsTrue(client.IsConnected);
 
                 await server.StopAsync();
                 await Task.Delay(500);
-                Assert.IsFalse(client.TryPingAsync().GetAwaiter().GetResult());
+                Assert.IsFalse(client.IsConnected);
 
                 for (var i = 0; i < 5; i++)
                 {
@@ -675,7 +671,6 @@ namespace MQTTnet.Tests.Client
                     }
                     catch
                     {
-                        // Ignore errors.
                     }
                 }
 
@@ -683,7 +678,7 @@ namespace MQTTnet.Tests.Client
                 await Task.Delay(500);
 
                 await client.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).Build());
-                await client.PingAsync();
+                Assert.IsTrue(client.IsConnected);
             }
         }
 
@@ -728,7 +723,7 @@ namespace MQTTnet.Tests.Client
                         replies.Add(eventArgs.ApplicationMessage.Topic);
                     }
 
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 }
 
                 client2.ApplicationMessageReceivedAsync += Handler2;
@@ -766,7 +761,7 @@ namespace MQTTnet.Tests.Client
                         replyReceived = true;
                     }
 
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 client2.ApplicationMessageReceivedAsync += async e =>
@@ -817,7 +812,7 @@ namespace MQTTnet.Tests.Client
                         replyReceived = true;
                     }
 
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await client.PublishStringAsync("request", null, MqttQualityOfServiceLevel.AtLeastOnce);
@@ -833,14 +828,14 @@ namespace MQTTnet.Tests.Client
         {
             using (var testEnvironment = new TestEnvironment(TestContext))
             {
-                await testEnvironment.StartServer();
+                var server = await testEnvironment.StartServer();
                 var client = await testEnvironment.ConnectClient();
 
-                Assert.IsTrue(client.TryPingAsync().GetAwaiter().GetResult());
+                Assert.IsTrue(client.IsConnected);
                 client.DisconnectedAsync += e =>
                 {
                     Assert.IsTrue(e.ClientWasConnected);
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await client.DisconnectAsync();
@@ -856,11 +851,11 @@ namespace MQTTnet.Tests.Client
                 var server = await testEnvironment.StartServer();
                 var client = await testEnvironment.ConnectClient();
 
-                Assert.IsTrue(client.TryPingAsync().GetAwaiter().GetResult());
+                Assert.IsTrue(client.IsConnected);
                 client.DisconnectedAsync += e =>
                 {
                     Assert.IsTrue(e.ClientWasConnected);
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await server.StopAsync();
@@ -897,7 +892,7 @@ namespace MQTTnet.Tests.Client
                         receivedMessages.Add(e.ApplicationMessage);
                     }
 
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await client.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("localhost", testEnvironment.ServerPort).Build());
@@ -922,14 +917,14 @@ namespace MQTTnet.Tests.Client
                 client1.DisconnectedAsync += c =>
                 {
                     disconnectedFired = true;
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 var messageReceived = false;
                 client1.ApplicationMessageReceivedAsync += e =>
                 {
                     messageReceived = true;
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await client1.SubscribeAsync(new MqttTopicFilterBuilder().WithTopic("topic1").WithExactlyOnceQoS().Build());
@@ -946,7 +941,7 @@ namespace MQTTnet.Tests.Client
                 await Task.Delay(500);
 
                 Assert.IsTrue(messageReceived);
-                Assert.IsTrue(client1.TryPingAsync().GetAwaiter().GetResult());
+                Assert.IsTrue(client1.IsConnected);
                 Assert.IsFalse(disconnectedFired);
             }
         }

Source/MQTTnet.Tests/Diagnostics/PacketInspection_Tests.cs

@@ -7,7 +7,7 @@ using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Internal;
+using MQTTnet.Implementations;
 
 namespace MQTTnet.Tests.Diagnostics
 {
@@ -33,7 +33,7 @@ namespace MQTTnet.Tests.Diagnostics
                     mqttClient.InspectPackage += eventArgs =>
                     {
                         packets.Add(eventArgs.Direction + ":" + Convert.ToBase64String(eventArgs.Buffer));
-                        return CompletedTask.Instance;
+                        return PlatformAbstractionLayer.CompletedTask;
                     };
                 
                     await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);

Source/MQTTnet.Tests/Extensions/MqttPacketWriterExtensions.cs

@@ -5,7 +5,7 @@
 using MQTTnet.Formatter;
 using MQTTnet.Protocol;
 
-namespace MQTTnet.Tests.Helpers
+namespace MQTTnet.Tests.Extensions
 {
     public static class MqttPacketWriterExtensions
     {

Source/MQTTnet.Tests/Extensions/WebSocket4Net_Tests.cs

@@ -1,51 +0,0 @@
-// 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.
-
-using System;
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Client;
-using MQTTnet.Exceptions;
-using MQTTnet.Extensions.WebSocket4Net;
-using MQTTnet.Tests.Helpers;
-
-namespace MQTTnet.Tests.Extensions
-{
-    [TestClass]
-    public sealed class WebSocket4Net_Tests
-    {
-        [TestMethod]
-        [ExpectedException(typeof(MqttCommunicationException))]
-        public async Task Connect_Failed_With_Invalid_Server()
-        {
-            var factory = new MqttFactory().UseWebSocket4Net();
-
-            using (var client = factory.CreateMqttClient())
-            {
-                var options = new MqttClientOptionsBuilder().WithWebSocketServer("ws://a.b/mqtt").WithTimeout(TimeSpan.FromSeconds(2)).Build();
-                await client.ConnectAsync(options).ConfigureAwait(false);
-            }
-        }
-
-        [TestMethod]
-        public void Use_Correct_Adapter()
-        {
-            // Should not throw exception
-            var factory = new MqttFactory().UseWebSocket4Net();
-            using (var client = factory.CreateMqttClient())
-            {
-                var adapterFactory = client.GetFieldValue("_adapterFactory");
-
-                Assert.IsInstanceOfType(adapterFactory, typeof(WebSocket4NetMqttClientAdapterFactory));
-            }
-        }
-
-        [TestMethod]
-        public void Use_WebSocket4Net()
-        {
-            // Should not throw exception
-            new MqttFactory().UseWebSocket4Net();
-        }
-    }
-}

Source/MQTTnet.Tests/Factory/MqttFactory_Tests.cs

@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Diagnostics;
 using MQTTnet.Extensions.ManagedClient;
-using MQTTnet.Internal;
+using MQTTnet.Implementations;
 using MQTTnet.Server;
 
 namespace MQTTnet.Tests.Factory
@@ -56,7 +56,7 @@ namespace MQTTnet.Tests.Factory
                 managedClient.ConnectingFailedAsync += e =>
                 {
                     tcs.TrySetResult(null);
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
                 
                 await Task.WhenAny(Task.Delay(managedClient.Options.ClientOptions.Timeout), tcs.Task);

Source/MQTTnet.Tests/Formatter/MqttBufferReader_Tests.cs

@@ -1,310 +0,0 @@
-// 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.
-
-using System;
-using System.Collections.Generic;
-using System.IO;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Exceptions;
-using MQTTnet.Formatter;
-
-namespace MQTTnet.Tests.Formatter
-{
-    [TestClass]
-    public sealed class MqttBufferReader_Tests
-    {
-        [TestMethod]
-        [ExpectedException(typeof(MqttProtocolViolationException), "Expected at least 4 bytes but there are only 3 bytes")]
-        public void Fire_Exception_If_Not_Enough_Data()
-        {
-            var buffer = new byte[] { 0, 1, 2 };
-
-            var reader = new MqttBufferReader();
-
-            reader.SetBuffer(buffer, 0, 3);
-
-            // 1 byte is missing.
-            reader.ReadFourByteInteger();
-        }
-
-        [TestMethod]
-        [ExpectedException(typeof(MqttProtocolViolationException), "Expected at least 4 bytes but there are only 3 bytes")]
-        public void Fire_Exception_If_Not_Enough_Data_With_Longer_Buffer()
-        {
-            var buffer = new byte[] { 0, 1, 2, 3, 4, 5, 6 };
-
-            var reader = new MqttBufferReader();
-
-            reader.SetBuffer(buffer, 0, 3);
-
-            // 1 byte is missing.
-            reader.ReadFourByteInteger();
-        }
-
-        [TestMethod]
-        public void Is_EndOfStream_Without_Buffer()
-        {
-            var reader = new MqttBufferReader();
-
-            Assert.IsTrue(reader.EndOfStream);
-            Assert.AreEqual(0, reader.BytesLeft);
-        }
-
-        [TestMethod]
-        public void Read_Remaining_Data_From_Larger_Buffer()
-        {
-            var buffer = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
-
-            var reader = new MqttBufferReader();
-
-            // The used buffer contains more data than used!
-            reader.SetBuffer(buffer, 0, 5);
-
-            // This should only read 5 bytes even if more data is in the buffer
-            // due to custom bounds.
-            var remainingData = reader.ReadRemainingData();
-
-            Assert.IsTrue(reader.EndOfStream);
-            Assert.AreEqual(0, reader.BytesLeft);
-            Assert.AreEqual(5, remainingData.Length);
-        }
-
-        [TestMethod]
-        public void Read_Various_Positions_and_Offsets()
-        {
-            const int NumBufferElements = 1000;
-            const int NumTestSequences = 10000;
-
-            const string TestString = "The quick brown fox jumps over the lazy dog.";
-
-            var rndSeed = Environment.TickCount;
-            // rndSeed = ...; // assign random seed here if there is an error so that it can be repeated
-            var rnd = new Random(rndSeed);
-            // rndSeed is printed when an assert fails
-
-            var bufferElements = new List<ElementReference>();
-
-            byte[] elementBuffer;
-
-            // Fill a buffer with strings or numbers in big endian format
-            using (var ms = new MemoryStream())
-            {
-                using (var bw = new BinaryWriter(ms))
-                {
-                    var bufferOffset = 0;
-
-                    for (var i = 0; i < NumBufferElements; i++)
-                    {
-                        var nextElementType = (ElementReference.BufferElementType)rnd.Next(ElementReference.NumBufferElementTypes);
-
-                        byte[] elementBytes = null;
-                        uint elementNumberValue = 0; // all element number values fit into uint
-                        string elementStringValue = null;
-                        var elementSize = 0;
-
-                        var alreadyBigEndian = false;
-                        switch (nextElementType)
-                        {
-                            case ElementReference.BufferElementType.Byte:
-                                var byteValue = (byte)i;
-                                elementNumberValue = byteValue;
-                                elementSize = sizeof(byte);
-                                elementBytes = new byte[1] { byteValue };
-                                alreadyBigEndian = true; // nothing to swap
-                                break;
-                            case ElementReference.BufferElementType.TwoByteInt:
-                                var ushortValue = (ushort)i;
-                                elementNumberValue = ushortValue;
-                                elementSize = sizeof(ushort);
-                                elementBytes = BitConverter.GetBytes(ushortValue);
-                                break;
-                            case ElementReference.BufferElementType.FourByteInt:
-                                var uintValue = (uint)i;
-                                elementNumberValue = uintValue;
-                                elementSize = sizeof(uint);
-                                elementBytes = BitConverter.GetBytes(uintValue);
-                                break;
-                            case ElementReference.BufferElementType.VariableSizeInt:
-                            {
-                                elementNumberValue = (uint)i;
-                                var writer = new MqttBufferWriter(4, 4);
-                                writer.WriteVariableByteInteger(elementNumberValue);
-                                elementSize = writer.Length;
-                                elementBytes = new byte[elementSize];
-                                var buffer = writer.GetBuffer();
-                                Array.Copy(buffer, elementBytes, elementSize);
-                                alreadyBigEndian = true; // nothing to swap
-                            }
-                                break;
-                            case ElementReference.BufferElementType.String:
-                            {
-                                var stringLen = rnd.Next(TestString.Length);
-                                elementStringValue = TestString.Substring(0, stringLen); // could be empty
-                                var writer = new MqttBufferWriter(stringLen + 1, stringLen + 1);
-                                writer.WriteString(elementStringValue);
-                                elementSize = writer.Length;
-                                elementBytes = new byte[elementSize];
-                                var buffer = writer.GetBuffer();
-                                Array.Copy(buffer, elementBytes, elementSize);
-                                alreadyBigEndian = true; // nothing to swap
-                            }
-                                break;
-                        }
-
-                        if (BitConverter.IsLittleEndian && !alreadyBigEndian)
-                        {
-                            Array.Reverse(elementBytes);
-                        }
-
-                        bw.Write(elementBytes);
-                        bufferElements.Add(new ElementReference(nextElementType, elementSize, elementNumberValue, elementStringValue, bufferOffset));
-                        bufferOffset += elementSize;
-                    }
-
-                    elementBuffer = ms.ToArray();
-                }
-            }
-
-            for (var i = 0; i < NumTestSequences; i++)
-            {
-                var firstElementIndex = rnd.Next(NumBufferElements - 1);
-                // segmentElementIndex will be < NumBufferElements - 1, which means there is at least one byte left for segment element count
-                var elementCount = rnd.Next(NumBufferElements - firstElementIndex) + 1;
-                var lastElementIndex = firstElementIndex + elementCount - 1;
-                // Use element index to get buffer offsets
-                var lastElement = bufferElements[lastElementIndex];
-                var segmentStartPosition = bufferElements[firstElementIndex].BufferOffset;
-                var segmentEndPosition = lastElement.BufferOffset + lastElement.Size;
-                var segmentLength = segmentEndPosition - segmentStartPosition;
-
-                var reader = new MqttBufferReader();
-                reader.SetBuffer(elementBuffer, segmentStartPosition, segmentLength);
-
-                // read all elements in the buffer segment; values should be as expected              
-                for (var n = 0; n < elementCount; n++)
-                {
-                    var element = bufferElements[firstElementIndex + n];
-                    uint elementNumberValue = 0;
-                    string elementStringValue = null;
-
-                    var expectedPosition = element.BufferOffset - segmentStartPosition;
-                    Assert.AreEqual(expectedPosition, reader.Position);
-
-                    switch (element.Type)
-                    {
-                        case ElementReference.BufferElementType.Byte:
-                        {
-                            elementNumberValue = reader.ReadByte();
-                        }
-                            break;
-                        case ElementReference.BufferElementType.TwoByteInt:
-                        {
-                            elementNumberValue = reader.ReadTwoByteInteger();
-                        }
-                            break;
-                        case ElementReference.BufferElementType.FourByteInt:
-                        {
-                            elementNumberValue = reader.ReadFourByteInteger();
-                        }
-                            break;
-                        case ElementReference.BufferElementType.VariableSizeInt:
-                        {
-                            elementNumberValue = reader.ReadVariableByteInteger();
-                        }
-                            break;
-                        case ElementReference.BufferElementType.String:
-                        {
-                            elementStringValue = reader.ReadString();
-                        }
-                            break;
-                    }
-
-                    if (elementStringValue != null)
-                    {
-                        Assert.AreEqual(elementStringValue, element.StringValue, $"'{elementStringValue}' not equal '{element.StringValue}' with random seed {rndSeed}.");
-                    }
-                    else
-                    {
-                        Assert.AreEqual(elementNumberValue, element.NumberValue, $"{elementNumberValue} not equal {element.NumberValue} with random seed {rndSeed}.");
-                    }
-                }
-
-                // confirm end of stream
-                Assert.AreEqual(0, reader.BytesLeft, "BytesLeft not zero as expected with random seed " + rndSeed);
-                Assert.IsTrue(reader.EndOfStream, "Not end of stream as expected with random seed " + rndSeed);
-            }
-        }
-
-        [TestMethod]
-        public void Report_Correct_Length_For_Full_Buffer()
-        {
-            var buffer = new byte[] { 5, 6, 7, 8, 9 };
-
-            var reader = new MqttBufferReader();
-            reader.SetBuffer(buffer, 0, 5);
-
-            Assert.IsFalse(reader.EndOfStream);
-            Assert.AreEqual(5, reader.BytesLeft);
-        }
-
-        [TestMethod]
-        public void Report_Correct_Length_For_Partial_End_Buffer()
-        {
-            var buffer = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
-
-            var reader = new MqttBufferReader();
-
-            // The used buffer contains more data than used!
-            reader.SetBuffer(buffer, 5, 5);
-
-            Assert.IsFalse(reader.EndOfStream);
-            Assert.AreEqual(5, reader.BytesLeft);
-        }
-
-        [TestMethod]
-        public void Report_Correct_Length_For_Partial_Start_Buffer()
-        {
-            var buffer = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
-
-            var reader = new MqttBufferReader();
-
-            // The used buffer contains more data than used!
-            reader.SetBuffer(buffer, 0, 5);
-
-            Assert.IsFalse(reader.EndOfStream);
-            Assert.AreEqual(5, reader.BytesLeft);
-        }
-
-
-        // Helper class to build up a reference to elements of various types in a buffer
-        class ElementReference
-        {
-            public enum BufferElementType
-            {
-                Byte,
-                TwoByteInt,
-                FourByteInt,
-                VariableSizeInt,
-                String
-            }
-
-            public const int NumBufferElementTypes = 5;
-
-            public ElementReference(BufferElementType type, int size, uint numberValue, string stringValue, int bufferOffset)
-            {
-                Type = type;
-                Size = size;
-                NumberValue = numberValue;
-                StringValue = stringValue;
-                BufferOffset = bufferOffset;
-            }
-
-            public int BufferOffset { get; }
-            public uint NumberValue { get; }
-            public int Size { get; }
-            public string StringValue { get; }
-            public BufferElementType Type { get; }
-        }
-    }
-}

Source/MQTTnet.Tests/Formatter/MqttPacketSerialization_V3_Binary_Tests.cs

@@ -13,12 +13,13 @@ using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
+using MQTTnet.Internal;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
-using MQTTnet.Tests.Helpers;
+using MQTTnet.Tests.Extensions;
 using MQTTnet.Tests.Mockups;
 
-namespace MQTTnet.Tests.Formatter
+namespace MQTTnet.Tests
 {
     [TestClass]
     public sealed class MqttPacketSerialization_V3_Binary_Tests

Source/MQTTnet.Tests/Formatter/MqttPacketSerialization_V3_Tests.cs

@@ -10,7 +10,7 @@ using MQTTnet.Formatter;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
 
-namespace MQTTnet.Tests.Formatter
+namespace MQTTnet.Tests
 {
     [TestClass]
     public sealed class MqttPacketSerialization_V3_Tests

Source/MQTTnet.Tests/Formatter/MqttPacketSerialization_V5_Tests.cs

@@ -9,7 +9,7 @@ using MQTTnet.Formatter;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
 
-namespace MQTTnet.Tests.Formatter
+namespace MQTTnet.Tests
 {
     [TestClass]
     public sealed class MqttPacketSerialization_V5_Tests

Source/MQTTnet.Tests/Helpers/MqttClientExtensions.cs

@@ -1,23 +0,0 @@
-// 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.
-
-using System;
-using MQTTnet.Client;
-using MQTTnet.Tests.Mockups;
-
-namespace MQTTnet.Tests.Helpers
-{
-    public static class MqttClientExtensions
-    {
-        public static TestApplicationMessageReceivedHandler TrackReceivedMessages(this IMqttClient client)
-        {
-            if (client == null)
-            {
-                throw new ArgumentNullException(nameof(client));
-            }
-
-            return new TestApplicationMessageReceivedHandler(client);
-        }
-    }
-}

Source/MQTTnet.Tests/Helpers/ReflectionExtensions.cs

@@ -1,28 +0,0 @@
-// 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.
-
-using System;
-using System.Reflection;
-
-namespace MQTTnet.Tests.Helpers
-{
-    public static class ReflectionExtensions
-    {
-        public static object GetFieldValue(this object source, string fieldName)
-        {
-            if (source == null)
-            {
-                throw new ArgumentNullException(nameof(source));
-            }
-
-            var field = source.GetType().GetField(fieldName, BindingFlags.Instance | BindingFlags.NonPublic);
-            if (field == null)
-            {
-                throw new ArgumentException($"Field {fieldName} not found.");
-            }
-            
-            return field.GetValue(source);
-        }
-    }
-}

Source/MQTTnet.Tests/Internal/AsyncEvent_Tests.cs

@@ -6,6 +6,7 @@ using System;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Implementations;
 using MQTTnet.Internal;
 
 namespace MQTTnet.Tests.Internal
@@ -15,28 +16,6 @@ namespace MQTTnet.Tests.Internal
     {
         int _testEventAsyncCount;
 
-        [TestMethod]
-        public async Task Attach_and_Detach_Sync_And_Async_EventHandler()
-        {
-            var testClass = new TestClass();
-
-            testClass.TestEventAsync += OnTestEventAsync;
-            testClass.TestEvent += OnTestEvent;
-
-            await testClass.FireEventAsync(EventArgs.Empty);
-            Assert.AreEqual(2, _testEventAsyncCount);
-
-            testClass.TestEvent -= OnTestEvent;
-
-            await testClass.FireEventAsync(EventArgs.Empty);
-            Assert.AreEqual(3, _testEventAsyncCount);
-
-            testClass.TestEventAsync -= OnTestEventAsync;
-
-            await testClass.FireEventAsync(EventArgs.Empty);
-            Assert.AreEqual(3, _testEventAsyncCount);
-        }
-
         [TestMethod]
         public async Task Attach_EventHandler()
         {
@@ -49,19 +28,6 @@ namespace MQTTnet.Tests.Internal
             Assert.AreEqual(1, _testEventAsyncCount);
         }
 
-        [TestMethod]
-        public async Task Attach_Sync_And_Async_EventHandler()
-        {
-            var testClass = new TestClass();
-
-            testClass.TestEventAsync += OnTestEventAsync;
-            testClass.TestEvent += OnTestEvent;
-
-            await testClass.FireEventAsync(EventArgs.Empty);
-
-            Assert.AreEqual(2, _testEventAsyncCount);
-        }
-
         [TestMethod]
         public async Task Detach_EventHandler()
         {
@@ -75,62 +41,22 @@ namespace MQTTnet.Tests.Internal
             Assert.AreEqual(0, _testEventAsyncCount);
         }
 
-        [TestMethod]
-        public void Has_Handlers()
-        {
-            var testClass = new TestClass();
-            testClass.TestEventAsync += OnTestEventAsync;
-
-            Assert.AreEqual(true, testClass.HasTestHandlers);
-        }
-
-        [TestMethod]
-        public void No_Handlers()
-        {
-            var testClass = new TestClass();
-
-            Assert.AreEqual(false, testClass.HasTestHandlers);
-        }
-
-        [TestMethod]
-        public void Remove_Handlers()
-        {
-            var testClass = new TestClass();
-            testClass.TestEventAsync += OnTestEventAsync;
-            testClass.TestEventAsync -= OnTestEventAsync;
-
-            Assert.AreEqual(false, testClass.HasTestHandlers);
-        }
-
-        void OnTestEvent(EventArgs arg)
-        {
-            Interlocked.Increment(ref _testEventAsyncCount);
-        }
-
         Task OnTestEventAsync(EventArgs arg)
         {
             Interlocked.Increment(ref _testEventAsyncCount);
-            return CompletedTask.Instance;
+            return PlatformAbstractionLayer.CompletedTask;
         }
 
         sealed class TestClass
         {
             readonly AsyncEvent<EventArgs> _testEvent = new AsyncEvent<EventArgs>();
 
-            public event Action<EventArgs> TestEvent
-            {
-                add => _testEvent.AddHandler(value);
-                remove => _testEvent.RemoveHandler(value);
-            }
-
             public event Func<EventArgs, Task> TestEventAsync
             {
                 add => _testEvent.AddHandler(value);
                 remove => _testEvent.RemoveHandler(value);
             }
 
-            public bool HasTestHandlers => _testEvent.HasHandlers;
-
             public Task FireEventAsync(EventArgs eventArgs)
             {
                 return _testEvent.InvokeAsync(eventArgs);

Source/MQTTnet.Tests/Internal/AsyncLock_Tests.cs

@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
@@ -12,186 +11,8 @@ using MQTTnet.Internal;
 namespace MQTTnet.Tests.Internal
 {
     [TestClass]
-    public sealed class AsyncLock_Tests
+    public class AsyncLock_Tests
     {
-        [TestMethod]
-        public async Task Cancellation_Of_Awaiter()
-        {
-            var @lock = new AsyncLock();
-
-            // This call will not yet "release" the lock due to missing _using_.
-            var releaser = await @lock.EnterAsync().ConfigureAwait(false);
-
-            var counter = 0;
-
-            Debug.WriteLine("Prepared locked lock.");
-
-            _ = Task.Run(
-                async () =>
-                {
-                    // SHOULD GET TIMEOUT!
-                    using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(1)))
-                    {
-                        using (await @lock.EnterAsync(timeout.Token))
-                        {
-                            Debug.WriteLine("Task 1 incremented");
-                            counter++;
-                        }
-                    }
-                });
-
-            _ = Task.Run(
-                async () =>
-                {
-                    // SHOULD GET TIMEOUT!
-                    using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(2)))
-                    {
-                        using (await @lock.EnterAsync(timeout.Token))
-                        {
-                            Debug.WriteLine("Task 2 incremented");
-                            counter++;
-                        }
-                    }
-                });
-
-            _ = Task.Run(
-                async () =>
-                {
-                    // SHOULD GET TIMEOUT!
-                    using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(3)))
-                    {
-                        using (await @lock.EnterAsync(timeout.Token))
-                        {
-                            Debug.WriteLine("Task 3 incremented");
-                            counter++;
-                        }
-                    }
-                });
-
-            _ = Task.Run(
-                async () =>
-                {
-                    using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(4)))
-                    {
-                        using (await @lock.EnterAsync(timeout.Token))
-                        {
-                            Debug.WriteLine("Task 4 incremented");
-                            counter++;
-                        }
-                    }
-                });
-
-            _ = Task.Run(
-                async () =>
-                {
-                    using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(5)))
-                    {
-                        using (await @lock.EnterAsync(timeout.Token))
-                        {
-                            Debug.WriteLine("Task 5 incremented");
-                            counter++;
-                        }
-                    }
-                });
-
-            _ = Task.Run(
-                async () =>
-                {
-                    using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(6)))
-                    {
-                        using (await @lock.EnterAsync(timeout.Token))
-                        {
-                            Debug.WriteLine("Task 6 incremented");
-                            counter++;
-                        }
-                    }
-                });
-
-            Debug.WriteLine("Delay before release...");
-            await Task.Delay(TimeSpan.FromSeconds(3.1));
-            releaser.Dispose();
-
-            Debug.WriteLine("Wait for all tasks...");
-            await Task.Delay(TimeSpan.FromSeconds(6.1));
-
-            Assert.AreEqual(3, counter);
-        }
-
-        [TestMethod]
-        public void Lock_Parallel_Tasks()
-        {
-            const int taskCount = 50;
-            
-            var @lock = new AsyncLock();
-            
-            var tasks = new Task[taskCount];
-            var globalI = 0;
-            for (var i = 0; i < taskCount; i++)
-            {
-#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
-                tasks[i] = Task.Run(
-                    async () =>
-                    {
-                        using (await @lock.EnterAsync())
-                        {
-                            var localI = globalI;
-                            await Task.Delay(5); // Increase the chance for wrong data.
-                            localI++;
-                            globalI = localI;
-                        }
-                    });
-#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
-            }
-
-            Task.WaitAll(tasks);
-            Assert.AreEqual(taskCount, globalI);
-        }
-
-        [TestMethod]
-        public void Lock_10_Parallel_Tasks_With_Dispose_Doesnt_Lockup()
-        {
-            const int ThreadsCount = 10;
-
-            var threads = new Task[ThreadsCount];
-            var @lock = new AsyncLock();
-            var globalI = 0;
-            for (var i = 0; i < ThreadsCount; i++)
-            {
-#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
-                threads[i] = Task.Run(
-                        async () =>
-                        {
-                            using (await @lock.EnterAsync())
-                            {
-                                var localI = globalI;
-                                await Task.Delay(10); // Increase the chance for wrong data.
-                                localI++;
-                                globalI = localI;
-                            }
-                        })
-                    .ContinueWith(
-                        x =>
-                        {
-                            if (globalI == 5)
-                            {
-                                @lock.Dispose();
-                                @lock = new AsyncLock();
-                            }
-
-                            if (x.Exception != null)
-                            {
-                                Debug.WriteLine(x.Exception.GetBaseException().GetType().Name);
-                            }
-                        });
-#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
-            }
-
-            Task.WaitAll(threads);
-
-            // Expect only 6 because the others are failing due to disposal (if (globalI == 5)).
-            Assert.AreEqual(6, globalI);
-        }
-
         [TestMethod]
         public async Task Lock_Serial_Calls()
         {
@@ -200,7 +21,7 @@ namespace MQTTnet.Tests.Internal
             var @lock = new AsyncLock();
             for (var i = 0; i < 100; i++)
             {
-                using (await @lock.EnterAsync().ConfigureAwait(false))
+                using (await @lock.WaitAsync(CancellationToken.None).ConfigureAwait(false))
                 {
                     sum++;
                 }
@@ -216,76 +37,66 @@ namespace MQTTnet.Tests.Internal
             var @lock = new AsyncLock();
 
             // This call will never "release" the lock due to missing _using_.
-            await @lock.EnterAsync().ConfigureAwait(false);
+            await @lock.WaitAsync(CancellationToken.None).ConfigureAwait(false);
 
             using (var cts = new CancellationTokenSource(TimeSpan.FromSeconds(3)))
             {
-                await @lock.EnterAsync(cts.Token).ConfigureAwait(false);
+                await @lock.WaitAsync(cts.Token).ConfigureAwait(false);
             }
         }
 
-        [TestMethod]
+        //[TestMethod]
-        public async Task Test_Cancellation_With_Later_Access()
+        //public async Task Test_Cancellation_With_Later_Access()
-        {
+        //{
-            var asyncLock = new AsyncLock();
+        //    var @lock = new AsyncLock();
 
-            var releaser = await asyncLock.EnterAsync().ConfigureAwait(false);
+        //    var releaser = await @lock.WaitAsync().ConfigureAwait(false);
 
-            try
+        //    try
-            {
+        //    {
-                using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(3)))
+        //        using (var cts = new CancellationTokenSource(TimeSpan.FromSeconds(3)))
-                {
+        //        {
-                    await asyncLock.EnterAsync(timeout.Token).ConfigureAwait(false);
+        //            await @lock.WaitAsync(cts.Token).ConfigureAwait(false);
-                }
+        //        }
+        //    }
+        //    catch (OperationCanceledException)
+        //    {
+        //    }
             
-                Assert.Fail("Exception should be thrown!");
+        //    releaser.Dispose();
-            }
-            catch (OperationCanceledException)
-            {
-            }
 
-            releaser.Dispose();
+        //    using (await @lock.WaitAsync().ConfigureAwait(false))
-
+        //    {
-            using (await asyncLock.EnterAsync(CancellationToken.None).ConfigureAwait(false))
+        //        // When the method finished, the thread got access.
-            {
+        //    }
-                // When the method finished, the thread got access.
+        //}
-            }
-        }
 
         [TestMethod]
-        public async Task Use_After_Cancellation()
+        public void Lock_10_Parallel_Tasks()
         {
+            const int ThreadsCount = 10;
+
+            var threads = new Task[ThreadsCount];
             var @lock = new AsyncLock();
-
+            var globalI = 0;
-            // This call will not yet "release" the lock due to missing _using_.
+            for (var i = 0; i < ThreadsCount; i++)
-            var releaser = await @lock.EnterAsync().ConfigureAwait(false);
-
-            try
             {
-                using (var cts = new CancellationTokenSource(TimeSpan.FromSeconds(3)))
+#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
+                threads[i] = Task.Run(async () =>
                 {
-                    await @lock.EnterAsync(cts.Token).ConfigureAwait(false);
+                    using (var releaser = await @lock.WaitAsync(CancellationToken.None))
-                }
+                    {
-            }
+                        var localI = globalI;
-            catch (OperationCanceledException)
+                        await Task.Delay(10); // Increase the chance for wrong data.
-            {
+                        localI++;
-                // Expected exception!
+                        globalI = localI;
+                    }
+                });
+#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
             }
 
-            releaser.Dispose();
+            Task.WaitAll(threads);
-
+            Assert.AreEqual(ThreadsCount, globalI);
-            // Regular usage after cancellation.
-            using (await @lock.EnterAsync().ConfigureAwait(false))
-            {
-            }
-
-            using (await @lock.EnterAsync().ConfigureAwait(false))
-            {
-            }
-
-            using (await @lock.EnterAsync().ConfigureAwait(false))
-            {
-            }
         }
     }
 }

Source/MQTTnet.Tests/Internal/AsyncSignal_Tests.cs

@@ -1,128 +0,0 @@
-// 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.
-
-using System;
-using System.Diagnostics;
-using System.Threading;
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Internal;
-
-namespace MQTTnet.Tests.Internal
-{
-    [TestClass]
-    public sealed class AsyncSignal_Tests
-    {
-        [TestMethod]
-        [ExpectedException(typeof(TaskCanceledException))]
-        public async Task Cancel_If_No_Signal()
-        {
-            var asyncSignal = new AsyncSignal();
-
-            using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(2)))
-            {
-                await asyncSignal.WaitAsync(timeout.Token);
-
-                Assert.Fail("There is no signal. So we must fail here!");
-            }
-        }
-
-        [TestMethod]
-        [ExpectedException(typeof(ObjectDisposedException))]
-        public async Task Dispose_Properly()
-        {
-            var asyncSignal = new AsyncSignal();
-
-            // The timeout will not be reached but another task will kill the async signal.
-            using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(999)))
-            {
-                _ = Task.Run(
-                    async () =>
-                    {
-                        await Task.Delay(2000, CancellationToken.None);
-                        asyncSignal.Dispose();
-                    },
-                    CancellationToken.None);
-
-                await asyncSignal.WaitAsync(timeout.Token);
-
-                Assert.Fail("There is no signal. So we must fail here!");
-            }
-        }
-
-        [TestMethod]
-        public async Task Reset_Signal()
-        {
-            var asyncSignal = new AsyncSignal();
-
-            // WaitAsync should fail because no signal is available.
-            for (var i = 0; i < 10; i++)
-            {
-                try
-                {
-                    using (var timeout = new CancellationTokenSource(TimeSpan.FromMilliseconds(100)))
-                    {
-                        await asyncSignal.WaitAsync(timeout.Token);
-                    }
-                    
-                    Assert.Fail("This must fail because the signal is not yet set.");
-                }
-                catch (OperationCanceledException)
-                {
-                }
-                
-                asyncSignal.Set();
-                
-                // WaitAsync should return directly because the signal is available.
-                await asyncSignal.WaitAsync();
-            }
-        }
-
-        [TestMethod]
-        public async Task Signal()
-        {
-            var asyncSignal = new AsyncSignal();
-
-            // The timeout will not be reached but another task will kill the async signal.
-            using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(3)))
-            {
-                var stopwatch = Stopwatch.StartNew();
-
-                _ = Task.Run(
-                    async () =>
-                    {
-                        await Task.Delay(1000, CancellationToken.None);
-                        asyncSignal.Set();
-                    },
-                    CancellationToken.None);
-
-                await asyncSignal.WaitAsync(timeout.Token);
-
-                stopwatch.Stop();
-
-                Assert.IsTrue(stopwatch.ElapsedMilliseconds > 900);
-            }
-        }
-
-        [TestMethod]
-        [ExpectedException(typeof(InvalidOperationException))]
-        public async Task Fail_For_Two_Waiters()
-        {
-            var asyncSignal = new AsyncSignal();
-
-            // This thread will wait properly because it is the first waiter.
-            _ = Task.Run(
-                async () =>
-                {
-                    await asyncSignal.WaitAsync();
-                },
-                CancellationToken.None);
-
-            await Task.Delay(1000);
-            
-            // Now the current thread must fail because there is already a waiter.
-            await asyncSignal.WaitAsync();
-        }
-    }
-}

Source/MQTTnet.Tests/Internal/MqttPacketBusItem_Tests.cs

@@ -1,43 +0,0 @@
-// 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.
-
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Internal;
-using MQTTnet.Packets;
-
-namespace MQTTnet.Tests.Internal
-{
-    [TestClass]
-    public sealed class MqttPacketBusItem_Tests
-    {
-        [TestMethod]
-        public void Fire_Completed_Event()
-        {
-            var eventFired = false;
-
-            var item = new MqttPacketBusItem(new MqttPublishPacket());
-            item.Completed += (_, __) =>
-            {
-                eventFired = true;
-            };
-
-            item.Complete();
-
-            Assert.IsTrue(eventFired);
-        }
-
-        [TestMethod]
-        [ExpectedException(typeof(TaskCanceledException))]
-        public async Task Wait_Packet_Bus_Item_After_Already_Canceled()
-        {
-            var item = new MqttPacketBusItem(new MqttPublishPacket());
-
-            // Finish the item before the actual 
-            item.Cancel();
-
-            await item.WaitAsync();
-        }
-    }
-}

Source/MQTTnet.Tests/Internal/MqttPacketBus_Tests.cs

@@ -14,6 +14,49 @@ namespace MQTTnet.Tests.Internal
     [TestClass]
     public sealed class MqttPacketBus_Tests
     {
+        [TestMethod]
+        [ExpectedException(typeof(OperationCanceledException))]
+        public async Task Wait_With_Empty_Bus()
+        {
+            var bus = new MqttPacketBus();
+
+            using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(1)))
+            {
+                await bus.DequeueItemAsync(timeout.Token);
+            }
+        }
+        
+        [TestMethod]
+        public async Task Fill_From_Different_Task()
+        {
+            const int MessageCount = 500;
+
+            var delayRandom = new Random();
+            
+            var bus = new MqttPacketBus();
+
+            _ = Task.Run(
+                () =>
+                {
+                    for (int i = 0; i < MessageCount; i++)
+                    {
+                        bus.EnqueueItem(new MqttPacketBusItem(MqttPingReqPacket.Instance), MqttPacketBusPartition.Health);
+                        
+                        Thread.Sleep(delayRandom.Next(0, 10));
+                    }
+                });
+            
+            for (var i = 0; i < MessageCount; i++)
+            {
+                using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(10)))
+                {
+                    await bus.DequeueItemAsync(timeout.Token);
+                }    
+            }
+            
+            Assert.AreEqual(0, bus.TotalItemsCount);
+        }
+        
         [TestMethod]
         public void Alternate_Priorities()
         {
@@ -46,42 +89,6 @@ namespace MQTTnet.Tests.Internal
             Assert.AreEqual(0, bus.TotalItemsCount);
         }
         
-        [TestMethod]
-        public void Await_Single_Packet()
-        {
-            var bus = new MqttPacketBus();
-
-            var delivered = false;
-
-            var item1 = new MqttPacketBusItem(new MqttPublishPacket());
-            var item2 = new MqttPacketBusItem(new MqttPublishPacket());
-
-            var item3 = new MqttPacketBusItem(new MqttPublishPacket());
-            item3.Completed += (_, __) =>
-            {
-                delivered = true;
-            };
-
-            bus.EnqueueItem(item1, MqttPacketBusPartition.Data);
-            bus.EnqueueItem(item2, MqttPacketBusPartition.Data);
-            bus.EnqueueItem(item3, MqttPacketBusPartition.Data);
-
-            Assert.IsFalse(delivered);
-
-            bus.DequeueItemAsync(CancellationToken.None).Result.Complete();
-
-            Assert.IsFalse(delivered);
-
-            bus.DequeueItemAsync(CancellationToken.None).Result.Complete();
-
-            Assert.IsFalse(delivered);
-
-            bus.DequeueItemAsync(CancellationToken.None).Result.Complete();
-
-            // The third packet has the event attached.
-            Assert.IsTrue(delivered);
-        }
-
         [TestMethod]
         public void Export_Packets_Without_Dequeue()
         {
@@ -106,46 +113,39 @@ namespace MQTTnet.Tests.Internal
         }
         
         [TestMethod]
-        public async Task Fill_From_Different_Task()
+        public void Await_Single_Packet()
-        {
-            const int MessageCount = 500;
-
-            var delayRandom = new Random();
-
-            var bus = new MqttPacketBus();
-
-            _ = Task.Run(
-                () =>
-                {
-                    for (var i = 0; i < MessageCount; i++)
-                    {
-                        bus.EnqueueItem(new MqttPacketBusItem(MqttPingReqPacket.Instance), MqttPacketBusPartition.Health);
-
-                        Thread.Sleep(delayRandom.Next(0, 10));
-                    }
-                });
-
-            for (var i = 0; i < MessageCount; i++)
-            {
-                using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(10)))
-                {
-                    await bus.DequeueItemAsync(timeout.Token);
-                }
-            }
-
-            Assert.AreEqual(0, bus.TotalItemsCount);
-        }
-
-        [TestMethod]
-        [ExpectedException(typeof(TaskCanceledException))]
-        public async Task Wait_With_Empty_Bus()
         {
             var bus = new MqttPacketBus();
 
-            using (var timeout = new CancellationTokenSource(TimeSpan.FromSeconds(1)))
+            var delivered = false;
+
+            var item1 = new MqttPacketBusItem(new MqttPublishPacket());
+            var item2 = new MqttPacketBusItem(new MqttPublishPacket());
+            
+            var item3 = new MqttPacketBusItem(new MqttPublishPacket());
+            item3.Delivered += (_, __) =>
             {
-                await bus.DequeueItemAsync(timeout.Token);
+                delivered = true;
-            }
+            };
+            
+            bus.EnqueueItem(item1, MqttPacketBusPartition.Data);
+            bus.EnqueueItem(item2, MqttPacketBusPartition.Data);
+            bus.EnqueueItem(item3, MqttPacketBusPartition.Data);
+            
+            Assert.IsFalse(delivered);
+
+            bus.DequeueItemAsync(CancellationToken.None).Result.MarkAsDelivered();
+            
+            Assert.IsFalse(delivered);
+            
+            bus.DequeueItemAsync(CancellationToken.None).Result.MarkAsDelivered();
+            
+            Assert.IsFalse(delivered);
+            
+            bus.DequeueItemAsync(CancellationToken.None).Result.MarkAsDelivered();
+            
+            // The third packet has the event attached.
+            Assert.IsTrue(delivered);
         }
     }
 }

Source/MQTTnet.Tests/MQTTnet.Tests.csproj

@@ -1,26 +1,27 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFrameworks>net452;net461;net48;netcoreapp3.1;net6.0</TargetFrameworks>
+        <TargetFrameworks>net452;net461;netcoreapp3.1;net6.0</TargetFrameworks>
         <IsPackable>false</IsPackable>
         <LangVersion>7.3</LangVersion>
         <EnableNETAnalyzers>false</EnableNETAnalyzers>
         <EnforceCodeStyleInBuild>false</EnforceCodeStyleInBuild>
         <DisableImplicitAspNetCoreAnalyzers>true</DisableImplicitAspNetCoreAnalyzers>
-        <NoWarn>1591;NETSDK1138</NoWarn>
     </PropertyGroup>
 
     <ItemGroup>
         <PackageReference Include="MSTest.TestAdapter" Version="2.2.10" />
         <PackageReference Include="MSTest.TestFramework" Version="2.2.10" />
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.2.0" />
+
+        <PackageReference Include="Microsoft.CodeAnalysis.Compilers" Version="4.0.1" />
+        <PackageReference Include="Microsoft.Net.Compilers" Version="4.0.1" />
     </ItemGroup>
 
     <ItemGroup>
         <ProjectReference Include="..\..\Source\MQTTnet.Extensions.ManagedClient\MQTTnet.Extensions.ManagedClient.csproj" />
         <ProjectReference Include="..\..\Source\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.csproj" />
         <ProjectReference Include="..\..\Source\MQTTnet\MQTTnet.csproj" />
-        <ProjectReference Include="..\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj" />
     </ItemGroup>
 
 </Project>

Source/MQTTnet.Tests/MQTTv5/Client_Tests.cs

@@ -8,9 +8,10 @@ using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
 using MQTTnet.Formatter;
-using MQTTnet.Internal;
+using MQTTnet.Implementations;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
+using MQTTnet.Tests.Mockups;
 
 namespace MQTTnet.Tests.MQTTv5
 {
@@ -42,7 +43,7 @@ namespace MQTTnet.Tests.MQTTv5
                 client.ApplicationMessageReceivedAsync += e =>
                 {
                     receivedMessage = e.ApplicationMessage;
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 await client.PublishAsync(new MqttApplicationMessageBuilder()
@@ -154,7 +155,7 @@ namespace MQTTnet.Tests.MQTTv5
                 var result = await client.PublishStringAsync("a", "b", MqttQualityOfServiceLevel.AtLeastOnce);
                 await client.DisconnectAsync();
 
-                Assert.AreEqual(MqttClientPublishReasonCode.NoMatchingSubscribers, result.ReasonCode);
+                Assert.AreEqual(MqttClientPublishReasonCode.Success, result.ReasonCode);
             }
         }
 
@@ -169,7 +170,7 @@ namespace MQTTnet.Tests.MQTTv5
                 var result = await client.PublishStringAsync("a", "b", MqttQualityOfServiceLevel.ExactlyOnce);
                 await client.DisconnectAsync();
 
-                Assert.AreEqual(MqttClientPublishReasonCode.NoMatchingSubscribers, result.ReasonCode);
+                Assert.AreEqual(MqttClientPublishReasonCode.Success, result.ReasonCode);
             }
         }
 
@@ -244,7 +245,7 @@ namespace MQTTnet.Tests.MQTTv5
                 receiver.ApplicationMessageReceivedAsync += e =>
                 {
                     receivedMessage = e.ApplicationMessage;
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 var sender = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithProtocolVersion(MqttProtocolVersion.V500));

Source/MQTTnet.Tests/MQTTv5/Server_Tests.cs

@@ -8,7 +8,7 @@ using MQTTnet.Formatter;
 using MQTTnet.Tests.Mockups;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Internal;
+using MQTTnet.Implementations;
 using MQTTnet.Protocol;
 
 namespace MQTTnet.Tests.MQTTv5
@@ -31,15 +31,15 @@ namespace MQTTnet.Tests.MQTTv5
                 c1.ApplicationMessageReceivedAsync += e =>
                 {
                     Interlocked.Increment(ref receivedMessagesCount);
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
                 
                 await c1.SubscribeAsync(new MqttTopicFilterBuilder().WithTopic("#").Build());
 
                 var c2 = await testEnvironment.ConnectClient(clientOptions);
-                c2.Dispose(); // Dispose will not send a DISCONNECT packet first so the will message must be sent.
+                c2.Dispose(); // Dispose will not send a DISCONNECT pattern first so the will message must be sent.
 
-                await LongTestDelay();
+                await Task.Delay(1000);
 
                 Assert.AreEqual(1, receivedMessagesCount);
             }
@@ -171,53 +171,11 @@ namespace MQTTnet.Tests.MQTTv5
                 // Session should be present
 
                 Assert.IsTrue(!result3.IsSessionPresent, "Session is present when it should not");
+
             }
         }
 
-        [TestMethod]
+        MqttClientOptions CreateClientOptions(TestEnvironment testEnvironment, string clientId, bool cleanSession, uint sessionExpiryInterval)
-        public async Task Disconnect_with_Reason()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                var disconnectReason = MqttClientDisconnectReason.UnspecifiedError;
-
-                string testClientId = null;
-
-                await testEnvironment.StartServer();
-
-                testEnvironment.Server.ClientConnectedAsync += e =>
-                {
-                    testClientId = e.ClientId;
-                    return CompletedTask.Instance;
-                };
-
-                var client = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithProtocolVersion(MqttProtocolVersion.V500));
-
-                client.DisconnectedAsync += e =>
-                {
-                    disconnectReason = e.Reason;
-                    return CompletedTask.Instance;
-                };
-
-                await LongTestDelay();
-
-                // Test client should be connected now
-
-                Assert.IsTrue(testClientId != null);
-
-                // Have the server disconnect the client with AdministrativeAction reason
-
-                await testEnvironment.Server.DisconnectClientAsync(testClientId, MqttDisconnectReasonCode.AdministrativeAction);
-
-                await LongTestDelay();
-
-                // The reason should be returned to the client in the DISCONNECT packet
-
-                Assert.AreEqual(MqttClientDisconnectReason.AdministrativeAction, disconnectReason);
-            }
-        }
-
-        static MqttClientOptions CreateClientOptions(TestEnvironment testEnvironment, string clientId, bool cleanSession, uint sessionExpiryInterval)
         {
             return testEnvironment.Factory.CreateClientOptionsBuilder()
                 .WithProtocolVersion(MqttProtocolVersion.V500)

Source/MQTTnet.Tests/Mockups/MemoryMqttChannel.cs

@@ -2,13 +2,11 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.IO;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Channel;
-using MQTTnet.Internal;
 
 namespace MQTTnet.Tests.Mockups
 {
@@ -34,12 +32,12 @@ namespace MQTTnet.Tests.Mockups
 
         public Task ConnectAsync(CancellationToken cancellationToken)
         {
-            return CompletedTask.Instance;
+            return Task.FromResult(0);
         }
 
         public Task DisconnectAsync(CancellationToken cancellationToken)
         {
-            return CompletedTask.Instance;
+            return Task.FromResult(0);
         }
 
         public Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
@@ -47,9 +45,9 @@ namespace MQTTnet.Tests.Mockups
             return _stream.ReadAsync(buffer, offset, count, cancellationToken);
         }
 
-        public Task WriteAsync(ArraySegment<byte> buffer, bool isEndOfPacket, CancellationToken cancellationToken)
+        public Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
         {
-            return _stream.WriteAsync(buffer.Array, buffer.Offset, buffer.Count, cancellationToken);
+            return _stream.WriteAsync(buffer, offset, count, cancellationToken);
         }
 
         public void Dispose()

Source/MQTTnet.Tests/Mockups/TestApplicationMessageReceivedHandler.cs

@@ -2,14 +2,12 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Text;
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
-using MQTTnet.Internal;
+using MQTTnet.Implementations;
 
 namespace MQTTnet.Tests.Mockups
 {
@@ -19,23 +17,7 @@ namespace MQTTnet.Tests.Mockups
 
         public TestApplicationMessageReceivedHandler(IMqttClient mqttClient)
         {
-            if (mqttClient == null)
+            mqttClient.ApplicationMessageReceivedAsync += MqttClientOnApplicationMessageReceivedAsync;
-            {
-                throw new ArgumentNullException(nameof(mqttClient));
-            }
-
-            mqttClient.ApplicationMessageReceivedAsync += OnApplicationMessageReceivedAsync;
-        }
-
-        public int Count
-        {
-            get
-            {
-                lock (_receivedEventArgs)
-                {
-                    return _receivedEventArgs.Count;
-                }
-            }
         }
 
         public List<MqttApplicationMessageReceivedEventArgs> ReceivedEventArgs
@@ -57,32 +39,14 @@ namespace MQTTnet.Tests.Mockups
             }
         }
 
-        public string GeneratePayloadSequence()
+        Task MqttClientOnApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
-        {
-            var sequence = new StringBuilder();
-
-            lock (_receivedEventArgs)
-            {
-                foreach (var receivedEventArg in _receivedEventArgs)
-                {
-                    var payload = receivedEventArg.ApplicationMessage.ConvertPayloadToString();
-
-                    // An empty payload is not part of the sequence!
-                    sequence.Append(payload);
-                }
-            }
-
-            return sequence.ToString();
-        }
-
-        Task OnApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
         {
             lock (_receivedEventArgs)
             {
                 _receivedEventArgs.Add(eventArgs);
             }
 
-            return CompletedTask.Instance;
+            return PlatformAbstractionLayer.CompletedTask;
         }
     }
 }

Source/MQTTnet.Tests/Mockups/TestEnvironment.cs

@@ -11,10 +11,9 @@ using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
 using MQTTnet.Diagnostics;
-using MQTTnet.Extensions.ManagedClient;
 using MQTTnet.Extensions.Rpc;
 using MQTTnet.Formatter;
-using MQTTnet.Internal;
+using MQTTnet.Implementations;
 using MQTTnet.LowLevelClient;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
@@ -200,16 +199,6 @@ namespace MQTTnet.Tests.Mockups
             return new TestApplicationMessageReceivedHandler(mqttClient);
         }
 
-        public TestApplicationMessageReceivedHandler CreateApplicationMessageHandler(IManagedMqttClient managedClient)
-        {
-            if (managedClient == null)
-            {
-                throw new ArgumentNullException(nameof(managedClient));
-            }
-
-            return new TestApplicationMessageReceivedHandler(managedClient.InternalClient);
-        }
-
         public IMqttClient CreateClient()
         {
             lock (_clients)
@@ -231,7 +220,7 @@ namespace MQTTnet.Tests.Mockups
                         }
                     }
 
-                    return CompletedTask.Instance;
+                    return PlatformAbstractionLayer.CompletedTask;
                 };
 
                 return client;
@@ -272,7 +261,7 @@ namespace MQTTnet.Tests.Mockups
                     }
                 }
 
-                return CompletedTask.Instance;
+                return PlatformAbstractionLayer.CompletedTask;
             };
 
             return Server;

Source/MQTTnet.Tests/Protocol_Tests.cs

@@ -8,7 +8,7 @@ using MQTTnet.Formatter;
 namespace MQTTnet.Tests
 {
     [TestClass]
-    public sealed class Protocol_Tests
+    public class Protocol_Tests
     {
         [TestMethod]
         public void Encode_Four_Byte_Integer()
@@ -30,26 +30,5 @@ namespace MQTTnet.Tests
                 writer.Reset(0);
             }
         }
-
-        [TestMethod]
-        public void Encode_Two_Byte_Integer()
-        {
-            var writer = new MqttBufferWriter(2, 2);
-
-            for (ushort value = 0; value < ushort.MaxValue; value++)
-            {
-                writer.WriteTwoByteInteger(value);
-
-                var buffer = writer.GetBuffer();
-
-                var reader = new MqttBufferReader();
-                reader.SetBuffer(buffer, 0, writer.Length);
-                var checkValue = reader.ReadTwoByteInteger();
-
-                Assert.AreEqual(value, checkValue);
-
-                writer.Reset(0);
-            }
-        }
     }
 }

Source/MQTTnet.Tests/RPC_Tests.cs

@@ -6,93 +6,67 @@ using System;
 using System.Text;
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Tests.Mockups;
 using MQTTnet.Client;
 using MQTTnet.Exceptions;
 using MQTTnet.Extensions.Rpc;
-using MQTTnet.Formatter;
-using MQTTnet.Internal;
 using MQTTnet.Protocol;
-using MQTTnet.Tests.Mockups;
+using MQTTnet.Formatter;
+using MQTTnet.Implementations;
 
-namespace MQTTnet.Tests.Extensions
+namespace MQTTnet.Tests
 {
     [TestClass]
-    public sealed class Rpc_Tests : BaseTestClass
+    public sealed class RPC_Tests : BaseTestClass
     {
-        [TestMethod]
-        public async Task Execute_Success_MQTT_V5_Mixed_Clients()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                await testEnvironment.StartServer();
-                var responseSender = await testEnvironment.ConnectClient();
-                await responseSender.SubscribeAsync("MQTTnet.RPC/+/ping");
-
-                responseSender.ApplicationMessageReceivedAsync += async e =>
-                {
-                    Assert.IsNull(e.ApplicationMessage.ResponseTopic);
-                    await responseSender.PublishStringAsync(e.ApplicationMessage.Topic + "/response", "pong");
-                };
-
-                var requestSender = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithProtocolVersion(MqttProtocolVersion.V500));
-
-                using (var rpcClient = new MqttRpcClient(requestSender, new MqttRpcClientOptionsBuilder().Build()))
-                {
-                    var response = await rpcClient.ExecuteAsync(TimeSpan.FromSeconds(5), "ping", "", MqttQualityOfServiceLevel.AtMostOnce);
-
-                    Assert.AreEqual("pong", Encoding.UTF8.GetString(response));
-                }
-            }
-        }
-
         [TestMethod]
         public Task Execute_Success_With_QoS_0()
         {
             return Execute_Success(MqttQualityOfServiceLevel.AtMostOnce, MqttProtocolVersion.V311);
         }
 
-        [TestMethod]
-        public Task Execute_Success_With_QoS_0_MQTT_V5()
-        {
-            return Execute_Success(MqttQualityOfServiceLevel.AtMostOnce, MqttProtocolVersion.V500);
-        }
-
-        [TestMethod]
-        public Task Execute_Success_With_QoS_0_MQTT_V5_Use_ResponseTopic()
-        {
-            return Execute_Success_MQTT_V5(MqttQualityOfServiceLevel.AtMostOnce);
-        }
-
         [TestMethod]
         public Task Execute_Success_With_QoS_1()
         {
             return Execute_Success(MqttQualityOfServiceLevel.AtLeastOnce, MqttProtocolVersion.V311);
         }
 
-        [TestMethod]
-        public Task Execute_Success_With_QoS_1_MQTT_V5()
-        {
-            return Execute_Success(MqttQualityOfServiceLevel.AtLeastOnce, MqttProtocolVersion.V500);
-        }
-
-        [TestMethod]
-        public Task Execute_Success_With_QoS_1_MQTT_V5_Use_ResponseTopic()
-        {
-            return Execute_Success_MQTT_V5(MqttQualityOfServiceLevel.AtLeastOnce);
-        }
-
         [TestMethod]
         public Task Execute_Success_With_QoS_2()
         {
             return Execute_Success(MqttQualityOfServiceLevel.ExactlyOnce, MqttProtocolVersion.V311);
         }
 
+        [TestMethod]
+        public Task Execute_Success_With_QoS_0_MQTT_V5()
+        {
+            return Execute_Success(MqttQualityOfServiceLevel.AtMostOnce, MqttProtocolVersion.V500);
+        }
+
+        [TestMethod]
+        public Task Execute_Success_With_QoS_1_MQTT_V5()
+        {
+            return Execute_Success(MqttQualityOfServiceLevel.AtLeastOnce, MqttProtocolVersion.V500);
+        }
+
         [TestMethod]
         public Task Execute_Success_With_QoS_2_MQTT_V5()
         {
             return Execute_Success(MqttQualityOfServiceLevel.ExactlyOnce, MqttProtocolVersion.V500);
         }
 
+        [TestMethod]
+        public Task Execute_Success_With_QoS_0_MQTT_V5_Use_ResponseTopic()
+        {
+            return Execute_Success_MQTT_V5(MqttQualityOfServiceLevel.AtMostOnce);
+        }
+
+        [TestMethod]
+        public Task Execute_Success_With_QoS_1_MQTT_V5_Use_ResponseTopic()
+        {
+            return Execute_Success_MQTT_V5(MqttQualityOfServiceLevel.AtLeastOnce);
+        }
+
         [TestMethod]
         public Task Execute_Success_With_QoS_2_MQTT_V5_Use_ResponseTopic()
         {
@@ -115,31 +89,6 @@ namespace MQTTnet.Tests.Extensions
             }
         }
 
-        [TestMethod]
-        [ExpectedException(typeof(MqttCommunicationTimedOutException))]
-        public async Task Execute_Timeout_MQTT_V5_Mixed_Clients()
-        {
-            using (var testEnvironment = new TestEnvironment(TestContext))
-            {
-                await testEnvironment.StartServer();
-                var responseSender = await testEnvironment.ConnectClient();
-                await responseSender.SubscribeAsync("MQTTnet.RPC/+/ping");
-
-                responseSender.ApplicationMessageReceivedAsync += async e =>
-                {
-                    Assert.IsNull(e.ApplicationMessage.ResponseTopic);
-                    await CompletedTask.Instance;
-                };
-
-                var requestSender = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithProtocolVersion(MqttProtocolVersion.V500));
-
-                using (var rpcClient = new MqttRpcClient(requestSender, new MqttRpcClientOptionsBuilder().Build()))
-                {
-                    var response = await rpcClient.ExecuteAsync(TimeSpan.FromSeconds(2), "ping", "", MqttQualityOfServiceLevel.AtMostOnce);
-                }
-            }
-        }
-
         [TestMethod]
         [ExpectedException(typeof(MqttCommunicationTimedOutException))]
         public async Task Execute_With_Custom_Topic_Names()
@@ -148,24 +97,14 @@ namespace MQTTnet.Tests.Extensions
             {
                 await testEnvironment.StartServer();
 
+                var requestSender = await testEnvironment.ConnectClient();
+
                 var rpcClient = await testEnvironment.ConnectRpcClient(new MqttRpcClientOptionsBuilder().WithTopicGenerationStrategy(new TestTopicStrategy()).Build());
 
                 await rpcClient.ExecuteAsync(TimeSpan.FromSeconds(2), "ping", "", MqttQualityOfServiceLevel.AtMostOnce);
             }
         }
 
-        [TestMethod]
-        public void Use_Factory()
-        {
-            var factory = new MqttFactory();
-            using (var client = factory.CreateMqttClient())
-            {
-                var rpcClient = factory.CreateMqttRpcClient(client);
-
-                Assert.IsNotNull(rpcClient);
-            }
-        }
-
         async Task Execute_Success(MqttQualityOfServiceLevel qosLevel, MqttProtocolVersion protocolVersion)
         {
             using (var testEnvironment = CreateTestEnvironment())
@@ -211,6 +150,57 @@ namespace MQTTnet.Tests.Extensions
             }
         }
 
+        [TestMethod]
+        public async Task Execute_Success_MQTT_V5_Mixed_Clients()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                await testEnvironment.StartServer();
+                var responseSender = await testEnvironment.ConnectClient();
+                await responseSender.SubscribeAsync("MQTTnet.RPC/+/ping", MqttQualityOfServiceLevel.AtMostOnce);
+
+                responseSender.ApplicationMessageReceivedAsync += async e =>
+                {
+                    Assert.IsNull(e.ApplicationMessage.ResponseTopic);
+                    await responseSender.PublishStringAsync(e.ApplicationMessage.Topic + "/response", "pong");
+                };
+
+                var requestSender = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithProtocolVersion(MqttProtocolVersion.V500));
+
+                using (var rpcClient = new MqttRpcClient(requestSender, new MqttRpcClientOptionsBuilder().Build()))
+                {
+                    var response = await rpcClient.ExecuteAsync(TimeSpan.FromSeconds(5), "ping", "", MqttQualityOfServiceLevel.AtMostOnce);
+
+                    Assert.AreEqual("pong", Encoding.UTF8.GetString(response));
+                }
+            }
+        }
+
+        [TestMethod]
+        [ExpectedException(typeof(MqttCommunicationTimedOutException))]
+        public async Task Execute_Timeout_MQTT_V5_Mixed_Clients()
+        {
+            using (var testEnvironment = new TestEnvironment(TestContext))
+            {
+                await testEnvironment.StartServer();
+                var responseSender = await testEnvironment.ConnectClient();
+                await responseSender.SubscribeAsync("MQTTnet.RPC/+/ping", MqttQualityOfServiceLevel.AtMostOnce);
+
+                responseSender.ApplicationMessageReceivedAsync += async e =>
+                {
+                    Assert.IsNull(e.ApplicationMessage.ResponseTopic);
+                    await PlatformAbstractionLayer.CompletedTask;
+                };
+
+                var requestSender = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithProtocolVersion(MqttProtocolVersion.V500));
+
+                using (var rpcClient = new MqttRpcClient(requestSender, new MqttRpcClientOptionsBuilder().Build()))
+                {
+                    var response = await rpcClient.ExecuteAsync(TimeSpan.FromSeconds(2), "ping", "", MqttQualityOfServiceLevel.AtMostOnce);
+                }
+            }
+        }
+
         class TestTopicStrategy : IMqttRpcClientTopicGenerationStrategy
         {
             public MqttRpcTopicPair CreateRpcTopics(TopicGenerationContext context)