Merge branch 'master' into feature-isconnected

Build/MQTTnet.AspNetCore.nuspec

@@ -11,15 +11,15 @@
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>This is a support library to integrate MQTTnet into AspNetCore.</description>
     <releaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</releaseNotes>
-    <copyright>Copyright Christian Kratky 2016-2019</copyright>
+    <copyright>Copyright Christian Kratky 2016-2020</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags>
     <dependencies>
       <dependency id="MQTTnet" version="$nugetVersion" />
 
-      <dependency id="Microsoft.AspNetCore.Connections.Abstractions" version="2.1.3" />
+      <dependency id="Microsoft.AspNetCore.Connections.Abstractions" version="3.1.3" />
-      <dependency id="Microsoft.AspNetCore.Http.Connections" version="1.0.3"  />
+      <dependency id="Microsoft.AspNetCore.Http.Connections" version="1.1.0"  />
-      <dependency id="Microsoft.AspNetCore.WebSockets" version="2.1.1" />
+      <dependency id="Microsoft.AspNetCore.WebSockets" version="2.2.1" />
-      <dependency id="Microsoft.Extensions.Hosting.Abstractions" version="2.1.1" />
+      <dependency id="Microsoft.Extensions.Hosting.Abstractions" version="3.1.3" />
     </dependencies>
   </metadata>
 

Build/MQTTnet.Extensions.ManagedClient.nuspec

@@ -11,7 +11,7 @@
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>This is an extension library which provides a managed MQTT client with additional features using MQTTnet.</description>
     <releaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</releaseNotes>
-    <copyright>Copyright Christian Kratky 2016-2019</copyright>
+    <copyright>Copyright Christian Kratky 2016-2020</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
     <dependencies>
       <dependency id="MQTTnet" version="$nugetVersion" />

Build/MQTTnet.Extensions.Rpc.nuspec

@@ -11,7 +11,7 @@
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>This is an extension library which allows executing synchronous device calls including a response using MQTTnet.</description>
     <releaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</releaseNotes>
-    <copyright>Copyright Christian Kratky 2016-2019</copyright>
+    <copyright>Copyright Christian Kratky 2016-2020</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
     <dependencies>
       <dependency id="MQTTnet" version="$nugetVersion" />

Build/MQTTnet.Extensions.WebSocket4Net.nuspec

@@ -11,7 +11,7 @@
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>This is an extension library which allows using _WebSocket4Net_ as transport for MQTTnet clients.</description>
     <releaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</releaseNotes>
-    <copyright>Copyright Christian Kratky 2016-2019</copyright>
+    <copyright>Copyright Christian Kratky 2016-2020</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
     <dependencies>
       <dependency id="MQTTnet" version="$nugetVersion" />

Build/MQTTnet.NETStandard.nuspec

@@ -11,7 +11,7 @@
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>This package contains the .NET Standard version of MQTTnet only.</description>
     <releaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</releaseNotes>
-    <copyright>Copyright Christian Kratky 2016-2019</copyright>
+    <copyright>Copyright Christian Kratky 2016-2020</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
     <dependencies>
       <group targetFramework="netstandard1.3">

Build/MQTTnet.nuspec

@@ -12,17 +12,23 @@
     <description>MQTTnet is a high performance .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker) and supports v3.1.0, v3.1.1 and v5.0.0 of the MQTT protocol.</description>
     <releaseNotes>
 * [All] Due to a merge issue not all changes are included in 3.0.8. All these changes are now included in this version.
+* [Core] Updated all nuget references.
+* [Core] Added MqttApplicationMessage.GetUserProperty() convenience method (thanks to @PMExtra).
+* [LowLevelMqttClient] Added low level MQTT client in order to provide more flexibility when using the MQTT protocol. This client requires detailed knowledge about the MQTT protocol.
+* [Client] Improve connection stability (thanks to @jltjohanlindqvist).
+* [Client] Support WithConnectionUri to configure client (thanks to @PMExtra).
 * [ManagedClient] Added builder class for MqttClientUnsubscribeOptions (thanks to @dominikviererbe).
 * [ManagedClient] Added support for persisted sessions (thansk to @PMExtra).
-* [Client] Improve connection stability (thanks to @jltjohanlindqvist).
 * [ManagedClient] Fixed a memory leak (thanks to @zawodskoj).
 * [ManagedClient] Improved internal subscription management (#569, thanks to @cstichlberger).
 * [ManagedClient] Refactored log messages (thanks to @cstichlberger).
 * [Server] Added support for assigned client IDs (MQTTv5 only) (thanks to @bcrosnier).
 * [Server] Added interceptor for unsubscriptions.
-* [MQTTnet.Server] Added interceptor for unsubscriptions.
+* [Server] Removed exceptions when user properties are set with MQTT protocol version 3.1
+* [Server] Added custom session items to the client status.
+* [Server] Added option to check whether the server is already started properly or not.
 * [MQTTnet.AspNetCore] improved compatibility with AspNetCore 3.1
-* [MQTTnet.Server] Added option to check whether the server is already started properly or not.
+* [MQTTnet.Server] Added interceptor for unsubscriptions.
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2020</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
@@ -40,7 +46,7 @@
         <dependency id="System.Net.WebSockets.Client" version="4.3.2" />
       </group>
       <group targetFramework="uap10.0">
-        <dependency id="Microsoft.NETCore.UniversalWindowsPlatform" version="6.2.8" />
+        <dependency id="Microsoft.NETCore.UniversalWindowsPlatform" version="6.2.10" />
       </group>
     </dependencies>
   </metadata>

MQTTnet.sln

@@ -53,6 +53,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Server", "Source\MQ
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Extensions.WebSocket4Net", "Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj", "{2BD01D53-4CA5-4142-BE8D-313876395E3E}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Apps", "Apps", "{A56E3128-1639-4F31-873A-325E14BB6295}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -270,7 +272,7 @@ Global
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{A7FF0C91-25DE-4BA6-B39E-F54E8DADF1CC} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
-		{FF1F72D6-9524-4422-9497-3CC0002216ED} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
+		{FF1F72D6-9524-4422-9497-3CC0002216ED} = {A56E3128-1639-4F31-873A-325E14BB6295}
 		{3587E506-55A2-4EB3-99C7-DC01E42D25D2} = {32A630A7-2598-41D7-B625-204CD906F5FB}
 		{3D283AAD-AAA8-4339-8394-52F80B6304DB} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
 		{C6FF8AEA-0855-41EC-A1F3-AC262225BAB9} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
@@ -279,7 +281,7 @@ Global
 		{998D04DD-7CB0-45F5-A393-E2495C16399E} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
 		{C400533A-8EBA-4F0B-BF4D-295C3708604B} = {12816BCC-AF9E-44A9-9AE5-C246AF2A0587}
 		{61B62223-F5D0-48E4-BBD6-2CBA9353CB5E} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
-		{5699FB8C-838C-4AB0-80A5-9CA809F9B65B} = {32A630A7-2598-41D7-B625-204CD906F5FB}
+		{5699FB8C-838C-4AB0-80A5-9CA809F9B65B} = {A56E3128-1639-4F31-873A-325E14BB6295}
 		{2BD01D53-4CA5-4142-BE8D-313876395E3E} = {12816BCC-AF9E-44A9-9AE5-C246AF2A0587}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution

Source/MQTTnet.AspnetCore/Client/MqttClientConnectionContextFactory.cs

@@ -1,17 +1,16 @@
-using System;
+using MQTTnet.Adapter;
-using System.Net;
-using MQTTnet.Adapter;
 using MQTTnet.AspNetCore.Client.Tcp;
-using MQTTnet.Client;
 using MQTTnet.Client.Options;
 using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
+using System;
+using System.Net;
 
 namespace MQTTnet.AspNetCore.Client
 {
     public class MqttClientConnectionContextFactory : IMqttClientAdapterFactory
     {
-        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetChildLogger logger)
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 

Source/MQTTnet.AspnetCore/Extensions/ServiceCollectionExtensions.cs

@@ -1,10 +1,10 @@
-using System;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
-using MQTTnet.Server;
 using MQTTnet.Implementations;
-using Microsoft.Extensions.DependencyInjection;
+using MQTTnet.Server;
+using System;
 
 namespace MQTTnet.AspNetCore
 {
@@ -23,7 +23,8 @@ namespace MQTTnet.AspNetCore
 
         public static IServiceCollection AddHostedMqttServer(this IServiceCollection services, Action<MqttServerOptionsBuilder> configure)
         {
-            services.AddSingleton<IMqttServerOptions>(s => {
+            services.AddSingleton<IMqttServerOptions>(s =>
+            {
                 var builder = new MqttServerOptionsBuilder();
                 configure(builder);
                 return builder.Build();
@@ -36,7 +37,8 @@ namespace MQTTnet.AspNetCore
 
         public static IServiceCollection AddHostedMqttServerWithServices(this IServiceCollection services, Action<AspNetMqttServerOptionsBuilder> configure)
         {
-            services.AddSingleton<IMqttServerOptions>(s => {
+            services.AddSingleton<IMqttServerOptions>(s =>
+            {
                 var builder = new AspNetMqttServerOptionsBuilder(s);
                 configure(builder);
                 return builder.Build();
@@ -60,10 +62,8 @@ namespace MQTTnet.AspNetCore
         private static IServiceCollection AddHostedMqttServer(this IServiceCollection services)
         {
             var logger = new MqttNetLogger();
-            var childLogger = logger.CreateChildLogger();
 
             services.AddSingleton<IMqttNetLogger>(logger);
-            services.AddSingleton(childLogger);
             services.AddSingleton<MqttHostedServer>();
             services.AddSingleton<IHostedService>(s => s.GetService<MqttHostedServer>());
             services.AddSingleton<IMqttServer>(s => s.GetService<MqttHostedServer>());

Source/MQTTnet.AspnetCore/MQTTnet.AspNetCore.csproj

@@ -21,10 +21,10 @@
   </ItemGroup>
     
   <ItemGroup Condition="'$(TargetFramework)' != 'netcoreapp3.1'">
-    <PackageReference Include="Microsoft.AspNetCore.Connections.Abstractions" Version="2.1.3" />
+    <PackageReference Include="Microsoft.AspNetCore.Connections.Abstractions" Version="3.1.3" />
-    <PackageReference Include="Microsoft.AspNetCore.Http.Connections" Version="1.0.3" />
+    <PackageReference Include="Microsoft.AspNetCore.Http.Connections" Version="1.1.0" />
-    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.1.1" />
+    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.2.1" />
-    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="2.1.1" />
+    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="3.1.3" />
   </ItemGroup>
 
   <ItemGroup>

Source/MQTTnet.AspnetCore/MqttWebSocketServerAdapter.cs

@@ -1,20 +1,20 @@
-using System;
+using Microsoft.AspNetCore.Http;
-using System.Net.WebSockets;
-using System.Threading.Tasks;
-using Microsoft.AspNetCore.Http;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
 using MQTTnet.Implementations;
 using MQTTnet.Server;
+using System;
+using System.Net.WebSockets;
+using System.Threading.Tasks;
 
 namespace MQTTnet.AspNetCore
 {
     public class MqttWebSocketServerAdapter : IMqttServerAdapter
     {
-        private readonly IMqttNetChildLogger _logger;
+        private readonly IMqttNetLogger _logger;
 
-        public MqttWebSocketServerAdapter(IMqttNetChildLogger logger)
+        public MqttWebSocketServerAdapter(IMqttNetLogger logger)
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs

@@ -1,9 +1,4 @@
-using System;
+using MQTTnet.Client;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Client;
 using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
 using MQTTnet.Client.Publishing;
@@ -13,6 +8,11 @@ using MQTTnet.Exceptions;
 using MQTTnet.Internal;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Extensions.ManagedClient
 {
@@ -33,7 +33,7 @@ namespace MQTTnet.Extensions.ManagedClient
         private readonly SemaphoreSlim _subscriptionsQueuedSignal = new SemaphoreSlim(0);
 
         private readonly IMqttClient _mqttClient;
-        private readonly IMqttNetChildLogger _logger;
+        private readonly IMqttNetLogger _logger;
 
         private readonly AsyncLock _messageQueueLock = new AsyncLock();
 
@@ -43,7 +43,7 @@ namespace MQTTnet.Extensions.ManagedClient
 
         private ManagedMqttClientStorageManager _storageManager;
 
-        public ManagedMqttClient(IMqttClient mqttClient, IMqttNetChildLogger logger)
+        public ManagedMqttClient(IMqttClient mqttClient, IMqttNetLogger logger)
         {
             _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
 

Source/MQTTnet.Extensions.ManagedClient/MqttFactoryExtensions.cs

@@ -1,5 +1,5 @@
-using System;
+using MQTTnet.Diagnostics;
-using MQTTnet.Diagnostics;
+using System;
 
 namespace MQTTnet.Extensions.ManagedClient
 {
@@ -9,7 +9,7 @@ namespace MQTTnet.Extensions.ManagedClient
         {
             if (factory == null) throw new ArgumentNullException(nameof(factory));
 
-            return new ManagedMqttClient(factory.CreateMqttClient(), factory.DefaultLogger.CreateChildLogger());
+            return new ManagedMqttClient(factory.CreateMqttClient(), factory.DefaultLogger);
         }
 
         public static IManagedMqttClient CreateManagedMqttClient(this IMqttFactory factory, IMqttNetLogger logger)
@@ -17,7 +17,7 @@ namespace MQTTnet.Extensions.ManagedClient
             if (factory == null) throw new ArgumentNullException(nameof(factory));
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
-            return new ManagedMqttClient(factory.CreateMqttClient(logger), logger.CreateChildLogger());
+            return new ManagedMqttClient(factory.CreateMqttClient(logger), logger);
         }
     }
 }

Source/MQTTnet.Extensions.WebSocket4Net/WebSocket4NetMqttClientAdapterFactory.cs

@@ -1,15 +1,15 @@
-using System;
+using MQTTnet.Adapter;
-using MQTTnet.Adapter;
 using MQTTnet.Client.Options;
 using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
 using MQTTnet.Implementations;
+using System;
 
 namespace MQTTnet.Extensions.WebSocket4Net
 {
     public class WebSocket4NetMqttClientAdapterFactory : IMqttClientAdapterFactory
     {
-        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetChildLogger logger)
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
             if (logger == null) throw new ArgumentNullException(nameof(logger));
@@ -17,19 +17,19 @@ namespace MQTTnet.Extensions.WebSocket4Net
             switch (options.ChannelOptions)
             {
                 case MqttClientTcpOptions _:
-                {
+                    {
-                    return new MqttChannelAdapter(new MqttTcpChannel(options), new MqttPacketFormatterAdapter(options.ProtocolVersion), logger);
+                        return new MqttChannelAdapter(new MqttTcpChannel(options), new MqttPacketFormatterAdapter(options.ProtocolVersion), logger);
-                }
+                    }
 
                 case MqttClientWebSocketOptions webSocketOptions:
-                {
+                    {
-                    return new MqttChannelAdapter(new WebSocket4NetMqttChannel(options, webSocketOptions), new MqttPacketFormatterAdapter(options.ProtocolVersion), logger);
+                        return new MqttChannelAdapter(new WebSocket4NetMqttChannel(options, webSocketOptions), new MqttPacketFormatterAdapter(options.ProtocolVersion), logger);
-                }
+                    }
 
                 default:
-                {
+                    {
-                    throw new NotSupportedException();
+                        throw new NotSupportedException();
-                }
+                    }
             }
         }
     }

Source/MQTTnet.Server/Logging/MqttNetChildLoggerWrapper.cs

@@ -1,43 +1,43 @@
-using System;
+//using MQTTnet.Diagnostics;
-using MQTTnet.Diagnostics;
+//using System;
 
-namespace MQTTnet.Server.Logging
+//namespace MQTTnet.Server.Logging
-{
+//{
-    public class MqttNetChildLoggerWrapper : IMqttNetChildLogger
+//    public class MqttNetChildLoggerWrapper : IMqttNetChildLogger
-    {
+//    {
-        private readonly MqttNetLoggerWrapper _logger;
+//        private readonly MqttNetLoggerWrapper _logger;
-        private readonly string _source;
+//        private readonly string _source;
 
-        public MqttNetChildLoggerWrapper(string source, MqttNetLoggerWrapper logger)
+//        public MqttNetChildLoggerWrapper(string source, MqttNetLoggerWrapper logger)
-        {
+//        {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+//            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
 
-            _source = source;
+//            _source = source;
-        }
+//        }
 
-        public IMqttNetChildLogger CreateChildLogger(string source = null)
+//        public IMqttNetLogger CreateChildLogger(string source = null)
-        {
+//        {
-            return _logger.CreateChildLogger(source);
+//            return _logger.CreateChildLogger(source);
-        }
+//        }
 
-        public void Verbose(string message, params object[] parameters)
+//        public void Verbose(string message, params object[] parameters)
-        {
+//        {
-            _logger.Publish(MqttNetLogLevel.Verbose, _source, message, parameters, null);
+//            _logger.Publish(MqttNetLogLevel.Verbose, _source, message, parameters, null);
-        }
+//        }
 
-        public void Info(string message, params object[] parameters)
+//        public void Info(string message, params object[] parameters)
-        {
+//        {
-            _logger.Publish(MqttNetLogLevel.Info, _source, message, parameters, null);
+//            _logger.Publish(MqttNetLogLevel.Info, _source, message, parameters, null);
-        }
+//        }
 
-        public void Warning(Exception exception, string message, params object[] parameters)
+//        public void Warning(Exception exception, string message, params object[] parameters)
-        {
+//        {
-            _logger.Publish(MqttNetLogLevel.Warning, _source, message, parameters, exception);
+//            _logger.Publish(MqttNetLogLevel.Warning, _source, message, parameters, exception);
-        }
+//        }
 
-        public void Error(Exception exception, string message, params object[] parameters)
+//        public void Error(Exception exception, string message, params object[] parameters)
-        {
+//        {
-            _logger.Publish(MqttNetLogLevel.Error, _source, message, parameters, exception);
+//            _logger.Publish(MqttNetLogLevel.Error, _source, message, parameters, exception);
-        }
+//        }
-    }
+//    }
-}
+//}

Source/MQTTnet.Server/Logging/MqttNetLoggerWrapper.cs

@@ -1,13 +1,13 @@
-using System;
+using Microsoft.Extensions.Logging;
-using System.Threading;
-using Microsoft.Extensions.Logging;
 using MQTTnet.Diagnostics;
+using System;
+using System.Threading;
 
 namespace MQTTnet.Server.Logging
 {
     public class MqttNetLoggerWrapper : IMqttNetLogger
     {
-        private readonly ILogger<MqttServer> _logger;
+        readonly ILogger<MqttServer> _logger;
 
         public MqttNetLoggerWrapper(ILogger<MqttServer> logger)
         {
@@ -16,25 +16,39 @@ namespace MQTTnet.Server.Logging
 
         public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
-        public IMqttNetChildLogger CreateChildLogger(string source = null)
+        public IMqttNetLogger CreateChildLogger(string source)
         {
-            return new MqttNetChildLoggerWrapper(source, this);
+            return new MqttNetLogger(source);
         }
 
-        public void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception)
+        public void Publish(MqttNetLogLevel level, string source, string message, object[] parameters, Exception exception)
         {
-            var convertedLogLevel = ConvertLogLevel(logLevel);
+            var convertedLogLevel = ConvertLogLevel(level);
             _logger.Log(convertedLogLevel, exception, message, parameters);
 
             var logMessagePublishedEvent = LogMessagePublished;
             if (logMessagePublishedEvent != null)
             {
-                var logMessage = new MqttNetLogMessage(null, DateTime.UtcNow, Thread.CurrentThread.ManagedThreadId, source, logLevel, message, exception);
+                var logMessage = new MqttNetLogMessage
+                {
+                    Timestamp = DateTime.UtcNow,
+                    ThreadId = Thread.CurrentThread.ManagedThreadId,
+                    Source = source,
+                    Level = level,
+                    Message = message,
+                    Exception = exception
+                };
+
                 logMessagePublishedEvent.Invoke(this, new MqttNetLogMessagePublishedEventArgs(logMessage));
             }
         }
 
-        private static LogLevel ConvertLogLevel(MqttNetLogLevel logLevel)
+        public void Publish(MqttNetLogLevel logLevel, string message, object[] parameters, Exception exception)
+        {
+            Publish(logLevel, null, message, parameters, exception);
+        }
+
+        static LogLevel ConvertLogLevel(MqttNetLogLevel logLevel)
         {
             switch (logLevel)
             {

Source/MQTTnet.Server/MQTTnet.Server.csproj

@@ -45,8 +45,10 @@
   <ItemGroup>
     <PackageReference Include="IronPython" Version="2.7.9" />
     <PackageReference Include="IronPython.StdLib" Version="2.7.9" />
-    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerGen" Version="5.0.0-rc2" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.1.3" />
-    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="5.0.0-rc2" />
+    <PackageReference Include="MSTest.TestAdapter" Version="2.1.1" />
+    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerGen" Version="5.3.1" />
+    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="5.3.1" />
   </ItemGroup>
 
   <ItemGroup>

Source/MQTTnet.Server/Mqtt/MqttServerService.cs

@@ -1,11 +1,4 @@
-using System;
+using IronPython.Runtime;
-using System.Collections.Generic;
-using System.Linq;
-using System.Net.WebSockets;
-using System.Security.Authentication;
-using System.Text;
-using System.Threading.Tasks;
-using IronPython.Runtime;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Logging;
 using MQTTnet.Adapter;
@@ -16,6 +9,13 @@ using MQTTnet.Protocol;
 using MQTTnet.Server.Configuration;
 using MQTTnet.Server.Scripting;
 using MQTTnet.Server.Status;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.WebSockets;
+using System.Security.Authentication;
+using System.Text;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Server.Mqtt
 {
@@ -65,11 +65,11 @@ namespace MQTTnet.Server.Mqtt
             _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
 
-            _webSocketServerAdapter = new MqttWebSocketServerAdapter(mqttFactory.Logger.CreateChildLogger());
+            _webSocketServerAdapter = new MqttWebSocketServerAdapter(mqttFactory.Logger);
 
             var adapters = new List<IMqttServerAdapter>
             {
-                new MqttTcpServerAdapter(mqttFactory.Logger.CreateChildLogger())
+                new MqttTcpServerAdapter(mqttFactory.Logger)
                 {
                     TreatSocketOpeningErrorAsWarning = true // Opening other ports than for HTTP is not allows in Azure App Services.
                 },

Source/MQTTnet/Adapter/IMqttClientAdapterFactory.cs

@@ -5,6 +5,6 @@ namespace MQTTnet.Adapter
 {
     public interface IMqttClientAdapterFactory
     {
-        IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetChildLogger logger);
+        IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger);
     }
 }

Source/MQTTnet/Adapter/MqttChannelAdapter.cs

@@ -14,12 +14,12 @@ using System.Threading.Tasks;
 
 namespace MQTTnet.Adapter
 {
-    public class MqttChannelAdapter : Disposable, IMqttChannelAdapter
+    public sealed class MqttChannelAdapter : Disposable, IMqttChannelAdapter
     {
         const uint ErrorOperationAborted = 0x800703E3;
         const int ReadBufferSize = 4096;  // TODO: Move buffer size to config
 
-        readonly IMqttNetChildLogger _logger;
+        readonly IMqttNetLogger _logger;
         readonly IMqttChannel _channel;
         readonly MqttPacketReader _packetReader;
 
@@ -30,7 +30,7 @@ namespace MQTTnet.Adapter
         long _bytesReceived;
         long _bytesSent;
 
-        public MqttChannelAdapter(IMqttChannel channel, MqttPacketFormatterAdapter packetFormatterAdapter, IMqttNetChildLogger logger)
+        public MqttChannelAdapter(IMqttChannel channel, MqttPacketFormatterAdapter packetFormatterAdapter, IMqttNetLogger logger)
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 

Source/MQTTnet/Client/MqttClient.cs

@@ -1,7 +1,3 @@
-using System;
-using System.Diagnostics;
-using System.Threading;
-using System.Threading.Tasks;
 using MQTTnet.Adapter;
 using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
@@ -17,6 +13,10 @@ using MQTTnet.Internal;
 using MQTTnet.PacketDispatcher;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
+using System;
+using System.Diagnostics;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Client
 {
@@ -29,7 +29,7 @@ namespace MQTTnet.Client
         private readonly object _disconnectLock = new object();
 
         private readonly IMqttClientAdapterFactory _adapterFactory;
-        private readonly IMqttNetChildLogger _logger;
+        private readonly IMqttNetLogger _logger;
 
         private CancellationTokenSource _backgroundCancellationTokenSource;
         private Task _packetReceiverTask;

Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs

@@ -1,19 +1,19 @@
-using System;
+using MQTTnet.Client.ExtendedAuthenticationExchange;
+using MQTTnet.Formatter;
+using System;
 using System.Linq;
 using System.Text;
-using MQTTnet.Client.ExtendedAuthenticationExchange;
-using MQTTnet.Formatter;
 
 namespace MQTTnet.Client.Options
 {
     public class MqttClientOptionsBuilder
     {
-        private readonly MqttClientOptions _options = new MqttClientOptions();
+        readonly MqttClientOptions _options = new MqttClientOptions();
 
-        private MqttClientTcpOptions _tcpOptions;
+        MqttClientTcpOptions _tcpOptions;
-        private MqttClientWebSocketOptions _webSocketOptions;
+        MqttClientWebSocketOptions _webSocketOptions;
-        private MqttClientOptionsBuilderTlsParameters _tlsParameters;
+        MqttClientOptionsBuilderTlsParameters _tlsParameters;
-        private MqttClientWebSocketProxyOptions _proxyOptions;
+        MqttClientWebSocketProxyOptions _proxyOptions;
 
         public MqttClientOptionsBuilder WithProtocolVersion(MqttProtocolVersion value)
         {

Source/MQTTnet/Diagnostics/IMqttNetChildLogger.cs

@@ -1,17 +0,0 @@
-using System;
-
-namespace MQTTnet.Diagnostics
-{
-    public interface IMqttNetChildLogger
-    {
-        IMqttNetChildLogger CreateChildLogger(string source = null);
-
-        void Verbose(string message, params object[] parameters);
-
-        void Info(string message, params object[] parameters);
-
-        void Warning(Exception exception, string message, params object[] parameters);
-
-        void Error(Exception exception, string message, params object[] parameters);
-    }
-}

Source/MQTTnet/Diagnostics/IMqttNetLogger.cs

@@ -6,8 +6,8 @@ namespace MQTTnet.Diagnostics
     {
         event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
-        IMqttNetChildLogger CreateChildLogger(string source = null);
+        IMqttNetLogger CreateChildLogger(string source);
 
-        void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception);
+        void Publish(MqttNetLogLevel logLevel, string message, object[] parameters, Exception exception);
     }
 }

Source/MQTTnet/Diagnostics/MqttNetChildLogger.cs

@@ -1,51 +0,0 @@
-using System;
-
-namespace MQTTnet.Diagnostics
-{
-    public class MqttNetChildLogger : IMqttNetChildLogger
-    {
-        private readonly IMqttNetLogger _logger;
-        private readonly string _source;
-
-        public MqttNetChildLogger(IMqttNetLogger logger, string source)
-        {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
-            _source = source;
-        }
-
-        public IMqttNetChildLogger CreateChildLogger(string source)
-        {
-            string childSource;
-            if (!string.IsNullOrEmpty(_source))
-            {
-                childSource = _source + "." + source;
-            }
-            else
-            {
-                childSource = source;
-            }
-
-            return new MqttNetChildLogger(_logger, childSource);
-        }
-
-        public void Verbose(string message, params object[] parameters)
-        {
-            _logger.Publish(MqttNetLogLevel.Verbose, _source, message, parameters, null);
-        }
-
-        public void Info(string message, params object[] parameters)
-        {
-            _logger.Publish(MqttNetLogLevel.Info, _source, message, parameters, null);
-        }
-
-        public void Warning(Exception exception, string message, params object[] parameters)
-        {
-            _logger.Publish(MqttNetLogLevel.Warning, _source, message, parameters, exception);
-        }
-
-        public void Error(Exception exception, string message, params object[] parameters)
-        {
-            _logger.Publish(MqttNetLogLevel.Error, _source, message, parameters, exception);
-        }
-    }
-}

Source/MQTTnet/Diagnostics/MqttNetLogMessage.cs

@@ -4,30 +4,19 @@ namespace MQTTnet.Diagnostics
 {
     public class MqttNetLogMessage
     {
-        public MqttNetLogMessage(string logId, DateTime timestamp, int threadId, string source, MqttNetLogLevel level, string message, Exception exception)
+        public string LogId { get; set; }
-        {
-            LogId = logId;
-            Timestamp = timestamp;
-            ThreadId = threadId;
-            Source = source;
-            Level = level;
-            Message = message;
-            Exception = exception;
-        }
 
-        public string LogId { get; }
+        public DateTime Timestamp { get; set; }
 
-        public DateTime Timestamp { get; }
+        public int ThreadId { get; set; }
 
-        public int ThreadId { get; }
+        public string Source { get; set; }
 
-        public string Source { get; }
+        public MqttNetLogLevel Level { get; set; }
 
-        public MqttNetLogLevel Level { get; }
+        public string Message { get; set; }
 
-        public string Message { get; }
+        public Exception Exception { get; set; }
-
-        public Exception Exception { get; }
 
         public override string ToString()
         {

Source/MQTTnet/Diagnostics/MqttNetLogMessagePublishedEventArgs.cs

@@ -6,9 +6,14 @@ namespace MQTTnet.Diagnostics
     {
         public MqttNetLogMessagePublishedEventArgs(MqttNetLogMessage logMessage)
         {
+            LogMessage = logMessage ?? throw new ArgumentNullException(nameof(logMessage));
+
             TraceMessage = logMessage ?? throw new ArgumentNullException(nameof(logMessage));
         }
 
+        [Obsolete("Use new proeprty LogMessage instead.")]
         public MqttNetLogMessage TraceMessage { get; }
+
+        public MqttNetLogMessage LogMessage { get; }
     }
 }

Source/MQTTnet/Diagnostics/MqttNetLogger.cs

@@ -4,26 +4,51 @@ namespace MQTTnet.Diagnostics
 {
     public class MqttNetLogger : IMqttNetLogger
     {
-        private readonly string _logId;
+        readonly string _logId;
+        readonly string _source;
 
-        public MqttNetLogger(string logId = null)
+        readonly MqttNetLogger _parentLogger;
+
+        public MqttNetLogger(string source, string logId)
         {
+            _source = source;
+            _logId = logId;
+        }
+
+        public MqttNetLogger()
+        {
+        }
+
+        public MqttNetLogger(string logId)
+        {
+            _logId = logId;
+        }
+
+        MqttNetLogger(MqttNetLogger parentLogger, string logId, string source)
+        {
+            _parentLogger = parentLogger ?? throw new ArgumentNullException(nameof(parentLogger));
+            _source = source ?? throw new ArgumentNullException(nameof(source));
+
             _logId = logId;
         }
 
         public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
-        public IMqttNetChildLogger CreateChildLogger(string source = null)
+        // TODO: Consider creating a LoggerFactory which will allow creating loggers. The logger factory will
+        // be the only place which has the published event.
+        public IMqttNetLogger CreateChildLogger(string source)
         {
-            return new MqttNetChildLogger(this, source);
+            if (source is null) throw new ArgumentNullException(nameof(source));
+
+            return new MqttNetLogger(this, _logId, source);
         }
 
-        public void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception)
+        public void Publish(MqttNetLogLevel level, string message, object[] parameters, Exception exception)
         {
             var hasLocalListeners = LogMessagePublished != null;
             var hasGlobalListeners = MqttNetGlobalLogger.HasListeners;
 
-            if (!hasLocalListeners && !hasGlobalListeners)
+            if (!hasLocalListeners && !hasGlobalListeners && _parentLogger == null)
             {
                 return;
             }
@@ -40,17 +65,35 @@ namespace MQTTnet.Diagnostics
                 }
             }
 
-            var traceMessage = new MqttNetLogMessage(_logId, DateTime.UtcNow, Environment.CurrentManagedThreadId, source, logLevel, message, exception);
+            var logMessage = new MqttNetLogMessage
+            {
+                LogId = _logId,
+                Timestamp = DateTime.UtcNow,
+                Source = _source,
+                ThreadId = Environment.CurrentManagedThreadId,
+                Level = level,
+                Message = message,
+                Exception = exception
+            };
 
             if (hasGlobalListeners)
             {
-                MqttNetGlobalLogger.Publish(traceMessage);
+                MqttNetGlobalLogger.Publish(logMessage);
             }
 
             if (hasLocalListeners)
             {
-                LogMessagePublished?.Invoke(this, new MqttNetLogMessagePublishedEventArgs(traceMessage));
+                LogMessagePublished?.Invoke(this, new MqttNetLogMessagePublishedEventArgs(logMessage));
             }
+
+            _parentLogger?.Publish(logMessage);
+        }
+
+        void Publish(MqttNetLogMessage logMessage)
+        {
+            LogMessagePublished?.Invoke(this, new MqttNetLogMessagePublishedEventArgs(logMessage));
+
+            _parentLogger?.Publish(logMessage);
         }
     }
 }

Source/MQTTnet/Diagnostics/MqttNetLoggerExtensions.cs

@@ -0,0 +1,35 @@
+using System;
+
+namespace MQTTnet.Diagnostics
+{
+    public static class MqttNetLoggerExtensions
+    {
+        public static void Verbose(this IMqttNetLogger logger, string message, params object[] parameters)
+        {
+            if (logger is null) throw new ArgumentNullException(nameof(logger));
+
+            logger.Publish(MqttNetLogLevel.Verbose, message, parameters, null);
+        }
+
+        public static void Info(this IMqttNetLogger logger, string message, params object[] parameters)
+        {
+            if (logger is null) throw new ArgumentNullException(nameof(logger));
+
+            logger.Publish(MqttNetLogLevel.Info, message, parameters, null);
+        }
+
+        public static void Warning(this IMqttNetLogger logger, Exception exception, string message, params object[] parameters)
+        {
+            if (logger is null) throw new ArgumentNullException(nameof(logger));
+
+            logger.Publish(MqttNetLogLevel.Warning, message, parameters, exception);
+        }
+
+        public static void Error(this IMqttNetLogger logger, Exception exception, string message, params object[] parameters)
+        {
+            if (logger is null) throw new ArgumentNullException(nameof(logger));
+
+            logger.Publish(MqttNetLogLevel.Error, message, parameters, exception);
+        }
+    }
+}

Source/MQTTnet/Diagnostics/TargetFrameworkProvider.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Diagnostics
 {
-    public static class TargetFrameworkInfoProvider
+    public static class TargetFrameworkProvider
     {
         public static string TargetFramework
         {

Source/MQTTnet/Extensions/MqttClientOptionsBuilderExtension.cs

@@ -0,0 +1,48 @@
+using System;
+using System.Linq;
+using MQTTnet.Client.Options;
+
+namespace MQTTnet.Extensions
+{
+    public static class MqttClientOptionsBuilderExtension
+    {
+        public static MqttClientOptionsBuilder WithConnectionUri(this MqttClientOptionsBuilder builder, Uri uri)
+        {
+            var port = uri.IsDefaultPort ? null : (int?) uri.Port;
+            switch (uri.Scheme.ToLower())
+            {
+                case "tcp":
+                case "mqtt":
+                    builder.WithTcpServer(uri.Host, port);
+                    break;
+
+                case "mqtts":
+                    builder.WithTcpServer(uri.Host, port).WithTls();
+                    break;
+
+                case "ws":
+                case "wss":
+                    builder.WithWebSocketServer(uri.ToString());
+                    break;
+
+                default:
+                    throw new ArgumentException("Unexpected scheme in uri.");
+            }
+            
+            if (!string.IsNullOrEmpty(uri.UserInfo))
+            {
+                var userInfo = uri.UserInfo.Split(':');
+                var username = userInfo[0];
+                var password = userInfo.Length > 1 ? userInfo[1] : "";
+                builder.WithCredentials(username, password);
+            }
+
+            return builder;
+        }
+
+        public static MqttClientOptionsBuilder WithConnectionUri(this MqttClientOptionsBuilder builder, string uri)
+        {
+            return WithConnectionUri(builder, new Uri(uri, UriKind.Absolute));
+        }
+    }
+}

Source/MQTTnet/Extensions/UserPropertyExtension.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Linq;
+
+namespace MQTTnet.Extensions
+{
+    public static class UserPropertyExtension
+    {
+        public static string GetUserProperty(this MqttApplicationMessage message, string propertyName, StringComparison comparisonType = StringComparison.Ordinal)
+        {
+            if (message == null) throw new ArgumentNullException(nameof(message));
+            if (propertyName == null) throw new ArgumentNullException(nameof(propertyName));
+
+            return message.UserProperties?.SingleOrDefault(up => up.Name.Equals(propertyName, comparisonType))?.Value;
+        }
+    }
+}

Source/MQTTnet/Formatter/V3/MqttV310DataConverter.cs

@@ -20,11 +20,6 @@ namespace MQTTnet.Formatter.V3
         {
             if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
 
-            if (applicationMessage.UserProperties?.Any() == true)
-            {
-                throw new MqttProtocolViolationException("User properties are not supported in MQTT version 3.");
-            }
-
             return new MqttPublishPacket
             {
                 Topic = applicationMessage.Topic,
@@ -171,11 +166,6 @@ namespace MQTTnet.Formatter.V3
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 
-            if (options.UserProperties?.Any() == true)
-            {
-                throw new MqttProtocolViolationException("User properties are not supported in MQTT version 3.");
-            }
-
             var subscribePacket = new MqttSubscribePacket();
             subscribePacket.TopicFilters.AddRange(options.TopicFilters);
             
@@ -186,11 +176,6 @@ namespace MQTTnet.Formatter.V3
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 
-            if (options.UserProperties?.Any() == true)
-            {
-                throw new MqttProtocolViolationException("User properties are not supported in MQTT version 3.");
-            }
-
             var unsubscribePacket = new MqttUnsubscribePacket();
             unsubscribePacket.TopicFilters.AddRange(options.TopicFilters);
 

Source/MQTTnet/Implementations/CrossPlatformSocket.cs

@@ -0,0 +1,229 @@
+using System;
+using System.Net;
+using System.Net.Sockets;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Implementations
+{
+    public sealed class CrossPlatformSocket : IDisposable
+    {
+        readonly Socket _socket;
+
+        public CrossPlatformSocket(AddressFamily addressFamily)
+        {
+            _socket = new Socket(addressFamily, SocketType.Stream, ProtocolType.Tcp);
+        }
+
+        public CrossPlatformSocket()
+        {
+            // Having this contructor is important because avoiding the address family as parameter
+            // will make use of dual mode in the .net framework.
+            _socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
+        }
+
+        public CrossPlatformSocket(Socket socket)
+        {
+            _socket = socket ?? throw new ArgumentNullException(nameof(socket));
+        }
+
+        public bool NoDelay
+        {
+            get
+            {
+                return (int)_socket.GetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay) > 0;
+            }
+
+            set
+            {
+                _socket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, value ? 1 : 0);
+            }
+        }
+
+        public bool DualMode
+        {
+            get
+            {
+                return _socket.DualMode;
+            }
+
+            set
+            {
+                _socket.DualMode = value;
+            }
+        }
+
+        public int ReceiveBufferSize
+        {
+            get
+            {
+                return _socket.ReceiveBufferSize;
+            }
+
+            set
+            {
+                _socket.ReceiveBufferSize = value;
+            }
+        }
+
+        public int SendBufferSize
+        {
+            get
+            {
+                return _socket.SendBufferSize;
+            }
+
+            set
+            {
+                _socket.SendBufferSize = value;
+            }
+        }
+
+        public EndPoint RemoteEndPoint
+        {
+            get
+            {
+                return _socket.RemoteEndPoint;
+            }
+        }
+
+        public bool ReuseAddress
+        {
+            get
+            {
+                return (int)_socket.GetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress) != 0;
+            }
+
+            set
+            {
+                _socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, value ? 1 : 0);
+            }
+        }
+
+        public async Task<CrossPlatformSocket> AcceptAsync()
+        {
+            try
+            {
+#if NET452 || NET461
+                var clientSocket = await Task.Factory.FromAsync(_socket.BeginAccept, _socket.EndAccept, null).ConfigureAwait(false);
+                return new CrossPlatformSocket(clientSocket);
+#else
+                var clientSocket = await _socket.AcceptAsync().ConfigureAwait(false);
+                return new CrossPlatformSocket(clientSocket);
+#endif
+            }
+            catch (ObjectDisposedException)
+            {
+                // This will happen when _socket.EndAccept gets called by Task library but the socket is already disposed.
+                return null;
+            }
+        }
+
+        public void Bind(EndPoint localEndPoint)
+        {
+            if (localEndPoint is null) throw new ArgumentNullException(nameof(localEndPoint));
+
+            _socket.Bind(localEndPoint);
+        }
+
+        public void Listen(int connectionBacklog)
+        {
+            _socket.Listen(connectionBacklog);
+        }
+
+        public async Task ConnectAsync(string host, int port, CancellationToken cancellationToken)
+        {
+            if (host is null) throw new ArgumentNullException(nameof(host));
+
+            try
+            {
+                // Workaround for: workaround for https://github.com/dotnet/corefx/issues/24430
+                using (cancellationToken.Register(() => _socket.Dispose()))
+                {
+                    cancellationToken.ThrowIfCancellationRequested();
+
+#if NET452 || NET461
+                    await Task.Factory.FromAsync(_socket.BeginConnect, _socket.EndConnect, host, port, null).ConfigureAwait(false);
+#else
+                    await _socket.ConnectAsync(host, port).ConfigureAwait(false);
+#endif
+                }
+            }
+            catch (ObjectDisposedException)
+            {
+                // This will happen when _socket.EndConnect gets called by Task library but the socket is already disposed.
+            }
+        }
+
+        public async Task SendAsync(ArraySegment<byte> buffer, SocketFlags socketFlags)
+        {
+            try
+            {
+#if NET452 || NET461
+                await Task.Factory.FromAsync(SocketWrapper.BeginSend, _socket.EndSend, new SocketWrapper(_socket, buffer, socketFlags)).ConfigureAwait(false);
+#else
+                await _socket.SendAsync(buffer, socketFlags).ConfigureAwait(false);
+#endif
+            }
+            catch (ObjectDisposedException)
+            {
+                // This will happen when _socket.EndConnect gets called by Task library but the socket is already disposed.
+            }
+        }
+
+        public async Task<int> ReceiveAsync(ArraySegment<byte> buffer, SocketFlags socketFlags)
+        {
+            try
+            {
+#if NET452 || NET461
+                return await Task.Factory.FromAsync(SocketWrapper.BeginReceive, _socket.EndReceive, new SocketWrapper(_socket, buffer, socketFlags)).ConfigureAwait(false);
+#else
+                return await _socket.ReceiveAsync(buffer, socketFlags).ConfigureAwait(false);
+#endif
+            }
+            catch (ObjectDisposedException)
+            {
+                // This will happen when _socket.EndReceive gets called by Task library but the socket is already disposed.
+                return -1;
+            }
+        }
+
+        public NetworkStream GetStream()
+        {
+            return new NetworkStream(_socket, true);
+        }
+
+        public void Dispose()
+        {
+            _socket?.Dispose();
+        }
+
+#if NET452 || NET461
+        class SocketWrapper
+        {
+            readonly Socket _socket;
+            readonly ArraySegment<byte> _buffer;
+            readonly SocketFlags _socketFlags;
+
+            public SocketWrapper(Socket socket, ArraySegment<byte> buffer, SocketFlags socketFlags)
+            {
+                _socket = socket;
+                _buffer = buffer;
+                _socketFlags = socketFlags;
+            }
+
+            public static IAsyncResult BeginSend(AsyncCallback callback, object state)
+            {
+                var socketWrapper = (SocketWrapper)state;
+                return socketWrapper._socket.BeginSend(socketWrapper._buffer.Array, socketWrapper._buffer.Offset, socketWrapper._buffer.Count, socketWrapper._socketFlags, callback, state);
+            }
+
+            public static IAsyncResult BeginReceive(AsyncCallback callback, object state)
+            {
+                var socketWrapper = (SocketWrapper)state;
+                return socketWrapper._socket.BeginReceive(socketWrapper._buffer.Array, socketWrapper._buffer.Offset, socketWrapper._buffer.Count, socketWrapper._socketFlags, callback, state);
+            }
+        }
+#endif
+    }
+}

Source/MQTTnet/Implementations/MqttClientAdapterFactory.cs

@@ -1,14 +1,14 @@
-using System;
+using MQTTnet.Adapter;
-using MQTTnet.Adapter;
 using MQTTnet.Client.Options;
 using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
+using System;
 
 namespace MQTTnet.Implementations
 {
     public class MqttClientAdapterFactory : IMqttClientAdapterFactory
     {
-        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetChildLogger logger)
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 

Source/MQTTnet/Implementations/MqttTcpChannel.cs

@@ -46,15 +46,15 @@ namespace MQTTnet.Implementations
 
         public async Task ConnectAsync(CancellationToken cancellationToken)
         {
-            Socket socket;
+            CrossPlatformSocket socket;
 
             if (_options.AddressFamily == AddressFamily.Unspecified)
             {
-                socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
+                socket = new CrossPlatformSocket();
             }
             else
             {
-                socket = new Socket(_options.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
+                socket = new CrossPlatformSocket(_options.AddressFamily);
             }
 
             socket.ReceiveBufferSize = _options.BufferSize;
@@ -69,20 +69,24 @@ namespace MQTTnet.Implementations
                 socket.DualMode = _options.DualMode.Value;
             }
 
-            // Workaround for: workaround for https://github.com/dotnet/corefx/issues/24430
+            await socket.ConnectAsync(_options.Server, _options.GetPort(), cancellationToken).ConfigureAwait(false);
-            using (cancellationToken.Register(() => socket.Dispose()))
-            {
-                await PlatformAbstractionLayer.ConnectAsync(socket, _options.Server, _options.GetPort()).ConfigureAwait(false);
-            }
 
-            var networkStream = new NetworkStream(socket, true);
+            var networkStream = socket.GetStream();
 
             if (_options.TlsOptions.UseTls)
             {
                 var sslStream = new SslStream(networkStream, false, InternalUserCertificateValidationCallback);
-                _stream = sslStream;
+                try
+                {
+                    await sslStream.AuthenticateAsClientAsync(_options.Server, LoadCertificates(), _options.TlsOptions.SslProtocol, !_options.TlsOptions.IgnoreCertificateRevocationErrors).ConfigureAwait(false);
+                }
+                catch
+                {
+                    sslStream.Dispose();
+                    throw;
+                }
 
-                await sslStream.AuthenticateAsClientAsync(_options.Server, LoadCertificates(), _options.TlsOptions.SslProtocol, !_options.TlsOptions.IgnoreCertificateRevocationErrors).ConfigureAwait(false);
+                _stream = sslStream;
             }
             else
             {
@@ -107,17 +111,14 @@ namespace MQTTnet.Implementations
                 // Workaround for: https://github.com/dotnet/corefx/issues/24430
                 using (cancellationToken.Register(Dispose))
                 {
-                    if (cancellationToken.IsCancellationRequested)
+                    cancellationToken.ThrowIfCancellationRequested();
-                    {
-                        return 0;
-                    }
 
                     return await _stream.ReadAsync(buffer, offset, count, cancellationToken).ConfigureAwait(false);
                 }
             }
             catch (ObjectDisposedException)
             {
-                return 0;
+                return -1;
             }
             catch (IOException exception)
             {
@@ -139,10 +140,7 @@ namespace MQTTnet.Implementations
                 // Workaround for: https://github.com/dotnet/corefx/issues/24430
                 using (cancellationToken.Register(Dispose))
                 {
-                    if (cancellationToken.IsCancellationRequested)
+                    cancellationToken.ThrowIfCancellationRequested();
-                    {
-                        return;
-                    }
 
                     await _stream.WriteAsync(buffer, offset, count, cancellationToken).ConfigureAwait(false);
                 }

Source/MQTTnet/Implementations/MqttTcpServerAdapter.Uwp.cs

@@ -11,14 +11,14 @@ using System.Threading.Tasks;
 
 namespace MQTTnet.Implementations
 {
-    public class MqttTcpServerAdapter : IMqttServerAdapter
+    public sealed class MqttTcpServerAdapter : IMqttServerAdapter
     {
-        private readonly IMqttNetChildLogger _logger;
+        readonly IMqttNetLogger _logger;
 
-        private IMqttServerOptions _options;
+        IMqttServerOptions _options;
-        private StreamSocketListener _listener;
+        StreamSocketListener _listener;
 
-        public MqttTcpServerAdapter(IMqttNetChildLogger logger)
+        public MqttTcpServerAdapter(IMqttNetLogger logger)
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
@@ -68,7 +68,7 @@ namespace MQTTnet.Implementations
             _listener = null;
         }
 
-        private async void OnConnectionReceivedAsync(StreamSocketListener sender, StreamSocketListenerConnectionReceivedEventArgs args)
+        async void OnConnectionReceivedAsync(StreamSocketListener sender, StreamSocketListenerConnectionReceivedEventArgs args)
         {
             try
             {

Source/MQTTnet/Implementations/MqttTcpServerAdapter.cs

@@ -1,4 +1,8 @@
 #if !WINDOWS_UWP
+using MQTTnet.Adapter;
+using MQTTnet.Diagnostics;
+using MQTTnet.Internal;
+using MQTTnet.Server;
 using System;
 using System.Collections.Generic;
 using System.Net;
@@ -6,21 +10,17 @@ using System.Net.Sockets;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Adapter;
-using MQTTnet.Diagnostics;
-using MQTTnet.Internal;
-using MQTTnet.Server;
 
 namespace MQTTnet.Implementations
 {
-    public class MqttTcpServerAdapter : Disposable, IMqttServerAdapter
+    public sealed class MqttTcpServerAdapter : Disposable, IMqttServerAdapter
     {
-        private readonly List<MqttTcpServerListener> _listeners = new List<MqttTcpServerListener>();
+        readonly List<MqttTcpServerListener> _listeners = new List<MqttTcpServerListener>();
-        private readonly IMqttNetChildLogger _logger;
+        readonly IMqttNetLogger _logger;
 
-        private CancellationTokenSource _cancellationTokenSource;
+        CancellationTokenSource _cancellationTokenSource;
 
-        public MqttTcpServerAdapter(IMqttNetChildLogger logger)
+        public MqttTcpServerAdapter(IMqttNetLogger logger)
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
@@ -77,7 +77,17 @@ namespace MQTTnet.Implementations
             return Task.FromResult(0);
         }
 
-        private void Cleanup()
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                Cleanup();
+            }
+
+            base.Dispose(disposing);
+        }
+
+        void Cleanup()
         {
             _cancellationTokenSource?.Cancel(false);
             _cancellationTokenSource?.Dispose();
@@ -91,16 +101,7 @@ namespace MQTTnet.Implementations
             _listeners.Clear();
         }
 
-        protected override void Dispose(bool disposing)
+        void RegisterListeners(MqttServerTcpEndpointBaseOptions options, X509Certificate2 tlsCertificate, CancellationToken cancellationToken)
-        {
-            if (disposing)
-            {
-                Cleanup();
-            }
-            base.Dispose(disposing);
-        }
-
-        private void RegisterListeners(MqttServerTcpEndpointBaseOptions options, X509Certificate2 tlsCertificate, CancellationToken cancellationToken)
         {
             if (!options.BoundInterNetworkAddress.Equals(IPAddress.None))
             {

Source/MQTTnet/Implementations/MqttTcpServerListener.cs

@@ -1,4 +1,9 @@
 #if !WINDOWS_UWP
+using MQTTnet.Adapter;
+using MQTTnet.Diagnostics;
+using MQTTnet.Formatter;
+using MQTTnet.Internal;
+using MQTTnet.Server;
 using System;
 using System.IO;
 using System.Net;
@@ -7,30 +12,25 @@ using System.Net.Sockets;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Adapter;
-using MQTTnet.Diagnostics;
-using MQTTnet.Formatter;
-using MQTTnet.Internal;
-using MQTTnet.Server;
 
 namespace MQTTnet.Implementations
 {
-    public class MqttTcpServerListener : IDisposable
+    public sealed class MqttTcpServerListener : IDisposable
     {
-        private readonly IMqttNetChildLogger _logger;
+        readonly IMqttNetLogger _logger;
-        private readonly AddressFamily _addressFamily;
+        readonly AddressFamily _addressFamily;
-        private readonly MqttServerTcpEndpointBaseOptions _options;
+        readonly MqttServerTcpEndpointBaseOptions _options;
-        private readonly MqttServerTlsTcpEndpointOptions _tlsOptions;
+        readonly MqttServerTlsTcpEndpointOptions _tlsOptions;
-        private readonly X509Certificate2 _tlsCertificate;
+        readonly X509Certificate2 _tlsCertificate;
 
-        private Socket _socket;
+        private CrossPlatformSocket _socket;
         private IPEndPoint _localEndPoint;
 
         public MqttTcpServerListener(
             AddressFamily addressFamily,
             MqttServerTcpEndpointBaseOptions options,
             X509Certificate2 tlsCertificate,
-            IMqttNetChildLogger logger)
+            IMqttNetLogger logger)
         {
             _addressFamily = addressFamily;
             _options = options;
@@ -59,18 +59,18 @@ namespace MQTTnet.Implementations
 
                 _logger.Info($"Starting TCP listener for {_localEndPoint} TLS={_tlsCertificate != null}.");
 
-                _socket = new Socket(_addressFamily, SocketType.Stream, ProtocolType.Tcp);
+                _socket = new CrossPlatformSocket(_addressFamily);
 
                 // Usage of socket options is described here: https://docs.microsoft.com/en-us/dotnet/api/system.net.sockets.socket.setsocketoption?view=netcore-2.2
 
                 if (_options.ReuseAddress)
                 {
-                    _socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
+                    _socket.ReuseAddress = true;
                 }
 
                 if (_options.NoDelay)
                 {
-                    _socket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, true);
+                    _socket.NoDelay = true;
                 }
 
                 _socket.Bind(_localEndPoint);
@@ -87,7 +87,7 @@ namespace MQTTnet.Implementations
                     throw;
                 }
 
-                _logger.Warning(exception,"Error while creating listener socket for local end point '{0}'.", _localEndPoint);
+                _logger.Warning(exception, "Error while creating listener socket for local end point '{0}'.", _localEndPoint);
                 return false;
             }
         }
@@ -101,13 +101,13 @@ namespace MQTTnet.Implementations
 #endif
         }
 
-        private async Task AcceptClientConnectionsAsync(CancellationToken cancellationToken)
+        async Task AcceptClientConnectionsAsync(CancellationToken cancellationToken)
         {
             while (!cancellationToken.IsCancellationRequested)
             {
                 try
                 {
-                    var clientSocket = await PlatformAbstractionLayer.AcceptAsync(_socket).ConfigureAwait(false);
+                    var clientSocket = await _socket.AcceptAsync().ConfigureAwait(false);
                     if (clientSocket == null)
                     {
                         continue;
@@ -135,7 +135,7 @@ namespace MQTTnet.Implementations
             }
         }
 
-        private async Task TryHandleClientConnectionAsync(Socket clientSocket)
+        async Task TryHandleClientConnectionAsync(CrossPlatformSocket clientSocket)
         {
             Stream stream = null;
             string remoteEndPoint = null;
@@ -151,7 +151,7 @@ namespace MQTTnet.Implementations
 
                 clientSocket.NoDelay = _options.NoDelay;
 
-                stream = new NetworkStream(clientSocket, true);
+                stream = clientSocket.GetStream();
 
                 X509Certificate2 clientCertificate = null;
 

Source/MQTTnet/Implementations/PlatformAbstractionLayer.cs

@@ -1,94 +1,9 @@
-using System;
+using System.Threading.Tasks;
-using System.Net;
-using System.Net.Sockets;
-using System.Threading.Tasks;
 
 namespace MQTTnet.Implementations
 {
     public static class PlatformAbstractionLayer
     {
-        // TODO: Consider creating primitives like "MqttNetSocket" which will wrap all required methods and do the platform stuff.
-        public static async Task<Socket> AcceptAsync(Socket socket)
-        {
-#if NET452 || NET461
-            try
-            {
-                return await Task.Factory.FromAsync(socket.BeginAccept, socket.EndAccept, null).ConfigureAwait(false);
-            }
-            catch (ObjectDisposedException)
-            {
-                return null;
-            }
-#else
-            return await socket.AcceptAsync().ConfigureAwait(false);
-#endif
-        }
-
-
-        public static Task ConnectAsync(Socket socket, IPAddress ip, int port)
-        {
-#if NET452 || NET461
-            return Task.Factory.FromAsync(socket.BeginConnect, socket.EndConnect, ip, port, null);
-#else
-            return socket.ConnectAsync(ip, port);
-#endif
-        }
-
-        public static Task ConnectAsync(Socket socket, string host, int port)
-        {
-#if NET452 || NET461
-            return Task.Factory.FromAsync(socket.BeginConnect, socket.EndConnect, host, port, null);
-#else
-            return socket.ConnectAsync(host, port);
-#endif
-        }
-
-#if NET452 || NET461
-        public class SocketWrapper 
-        {
-            private readonly Socket _socket;
-            private readonly ArraySegment<byte> _buffer;
-            private readonly SocketFlags _socketFlags;
-
-            public SocketWrapper(Socket socket, ArraySegment<byte> buffer, SocketFlags socketFlags)
-            {
-                _socket = socket;
-                _buffer = buffer;
-                _socketFlags = socketFlags;
-            }
-
-            public static IAsyncResult BeginSend(AsyncCallback callback, object state)
-            {
-                var real = (SocketWrapper)state;
-                return real._socket.BeginSend(real._buffer.Array, real._buffer.Offset, real._buffer.Count, real._socketFlags, callback, state);
-            }
-
-            public static IAsyncResult BeginReceive(AsyncCallback callback, object state)
-            {
-                var real = (SocketWrapper)state;
-                return real._socket.BeginReceive(real._buffer.Array, real._buffer.Offset, real._buffer.Count, real._socketFlags, callback, state);
-            }
-        }
-#endif
-
-        public static Task SendAsync(Socket socket, ArraySegment<byte> buffer, SocketFlags socketFlags)
-        {
-#if NET452 || NET461            
-            return Task.Factory.FromAsync(SocketWrapper.BeginSend, socket.EndSend, new SocketWrapper(socket, buffer, socketFlags));
-#else
-            return socket.SendAsync(buffer, socketFlags);
-#endif
-        }
-
-        public static Task<int> ReceiveAsync(Socket socket, ArraySegment<byte> buffer, SocketFlags socketFlags)
-        {
-#if NET452 || NET461
-            return Task.Factory.FromAsync(SocketWrapper.BeginReceive, socket.EndReceive, new SocketWrapper(socket, buffer, socketFlags));
-#else
-            return socket.ReceiveAsync(buffer, socketFlags);
-#endif
-        }
-
         public static Task CompletedTask
         {
             get

Source/MQTTnet/Internal/TaskExtensions.cs

@@ -1,11 +1,11 @@
-using System.Threading.Tasks;
+using MQTTnet.Diagnostics;
-using MQTTnet.Diagnostics;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Internal
 {
     public static class TaskExtensions
     {
-        public static void Forget(this Task task, IMqttNetChildLogger logger)
+        public static void Forget(this Task task, IMqttNetLogger logger)
         {
             task?.ContinueWith(t =>
                 {

Source/MQTTnet/LowLevelClient/ILowLevelMqttClient.cs

@@ -0,0 +1,19 @@
+using MQTTnet.Client.Options;
+using MQTTnet.Packets;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.LowLevelClient
+{
+    public interface ILowLevelMqttClient : IDisposable
+    {
+        Task ConnectAsync(IMqttClientOptions options, CancellationToken cancellationToken);
+
+        Task DisconnectAsync(CancellationToken cancellationToken);
+
+        Task SendAsync(MqttBasePacket packet, CancellationToken cancellationToken);
+
+        Task<MqttBasePacket> ReceiveAsync(CancellationToken cancellationToken);
+    }
+}

Source/MQTTnet/LowLevelClient/LowLevelMqttClient.cs

@@ -0,0 +1,128 @@
+using MQTTnet.Adapter;
+using MQTTnet.Client.Options;
+using MQTTnet.Diagnostics;
+using MQTTnet.Packets;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.LowLevelClient
+{
+    public sealed class LowLevelMqttClient : ILowLevelMqttClient
+    {
+        readonly IMqttNetLogger _logger;
+        readonly IMqttClientAdapterFactory _clientAdapterFactory;
+
+        IMqttChannelAdapter _adapter;
+        IMqttClientOptions _options;
+
+        public LowLevelMqttClient(IMqttClientAdapterFactory clientAdapterFactory, IMqttNetLogger logger)
+        {
+            if (clientAdapterFactory is null) throw new ArgumentNullException(nameof(clientAdapterFactory));
+            if (logger is null) throw new ArgumentNullException(nameof(logger));
+
+            _clientAdapterFactory = clientAdapterFactory;
+            _logger = logger.CreateChildLogger(nameof(LowLevelMqttClient));
+        }
+
+        bool IsConnected => _adapter != null;
+
+        public async Task ConnectAsync(IMqttClientOptions options, CancellationToken cancellationToken)
+        {
+            if (options is null) throw new ArgumentNullException(nameof(options));
+
+            if (_adapter != null)
+            {
+                throw new InvalidOperationException("Low level MQTT client is already connected. Disconnect first before connecting again.");
+            }
+
+            var newAdapter = _clientAdapterFactory.CreateClientAdapter(options, _logger);
+
+            try
+            {
+                _logger.Verbose($"Trying to connect with server '{options.ChannelOptions}' (Timeout={options.CommunicationTimeout}).");
+                await newAdapter.ConnectAsync(options.CommunicationTimeout, cancellationToken).ConfigureAwait(false);
+                _logger.Verbose("Connection with server established.");
+
+                _options = options;
+            }
+            catch (Exception)
+            {
+                _adapter.Dispose();
+                throw;
+            }
+
+            _adapter = newAdapter;
+        }
+
+        public async Task DisconnectAsync(CancellationToken cancellationToken)
+        {
+            if (_adapter == null)
+            {
+                return;
+            }
+
+            await SafeDisconnect(cancellationToken).ConfigureAwait(false);
+            _adapter = null;
+        }
+
+        public async Task SendAsync(MqttBasePacket packet, CancellationToken cancellationToken)
+        {
+            if (packet is null) throw new ArgumentNullException(nameof(packet));
+
+            if (_adapter == null)
+            {
+                throw new InvalidOperationException("Low level MQTT client is not connected.");
+            }
+
+            try
+            {
+                await _adapter.SendPacketAsync(packet, _options.CommunicationTimeout, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                await SafeDisconnect(cancellationToken).ConfigureAwait(false);
+                throw;
+            }
+        }
+
+        public async Task<MqttBasePacket> ReceiveAsync(CancellationToken cancellationToken)
+        {
+            if (_adapter == null)
+            {
+                throw new InvalidOperationException("Low level MQTT client is not connected.");
+            }
+
+            try
+            {
+                return await _adapter.ReceivePacketAsync(_options.CommunicationTimeout, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                await SafeDisconnect(cancellationToken).ConfigureAwait(false);
+                throw;
+            }
+        }
+
+        public void Dispose()
+        {
+            _adapter?.Dispose();
+        }
+
+        async Task SafeDisconnect(CancellationToken cancellationToken)
+        {
+            try
+            {
+                await _adapter.DisconnectAsync(_options.CommunicationTimeout, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception exception)
+            {
+                _logger.Error(exception, "Error while disconnecting.");
+            }
+            finally
+            {
+                _adapter.Dispose();
+            }
+        }
+    }
+}

Source/MQTTnet/MQTTnet.csproj

@@ -64,7 +64,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NETCore.UniversalWindowsPlatform" Version="6.2.9" />
+    <PackageReference Include="Microsoft.NETCore.UniversalWindowsPlatform" Version="6.2.10" />
   </ItemGroup>
   
 </Project>

Source/MQTTnet/MqttFactory.cs

@@ -1,16 +1,17 @@
-using System;
+using MQTTnet.Adapter;
-using System.Collections.Generic;
-using MQTTnet.Adapter;
 using MQTTnet.Client;
 using MQTTnet.Diagnostics;
 using MQTTnet.Implementations;
+using MQTTnet.LowLevelClient;
 using MQTTnet.Server;
+using System;
+using System.Collections.Generic;
 
 namespace MQTTnet
 {
-    public class MqttFactory : IMqttFactory
+    public sealed class MqttFactory : IMqttFactory
     {
-        private IMqttClientAdapterFactory _clientAdapterFactory = new MqttClientAdapterFactory();
+        IMqttClientAdapterFactory _clientAdapterFactory = new MqttClientAdapterFactory();
 
         public MqttFactory() : this(new MqttNetLogger())
         {
@@ -29,6 +30,33 @@ namespace MQTTnet
             return this;
         }
 
+        public ILowLevelMqttClient CreateLowLevelMqttClient()
+        {
+            return CreateLowLevelMqttClient(DefaultLogger);
+        }
+
+        public ILowLevelMqttClient CreateLowLevelMqttClient(IMqttNetLogger logger)
+        {
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
+            return new LowLevelMqttClient(_clientAdapterFactory, logger);
+        }
+
+        public ILowLevelMqttClient CreateLowLevelMqttClient(IMqttClientAdapterFactory clientAdapterFactory)
+        {
+            if (clientAdapterFactory == null) throw new ArgumentNullException(nameof(clientAdapterFactory));
+
+            return new LowLevelMqttClient(_clientAdapterFactory, DefaultLogger);
+        }
+
+        public ILowLevelMqttClient CreateLowLevelMqttClient(IMqttNetLogger logger, IMqttClientAdapterFactory clientAdapterFactoryy)
+        {
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            if (clientAdapterFactoryy == null) throw new ArgumentNullException(nameof(clientAdapterFactoryy));
+
+            return new LowLevelMqttClient(_clientAdapterFactory, logger);
+        }
+
         public IMqttClient CreateMqttClient()
         {
             return CreateMqttClient(DefaultLogger);
@@ -65,7 +93,7 @@ namespace MQTTnet
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
-            return CreateMqttServer(new List<IMqttServerAdapter> { new MqttTcpServerAdapter(logger.CreateChildLogger()) }, logger);
+            return CreateMqttServer(new List<IMqttServerAdapter> { new MqttTcpServerAdapter(logger) }, logger);
         }
 
         public IMqttServer CreateMqttServer(IEnumerable<IMqttServerAdapter> serverAdapters, IMqttNetLogger logger)
@@ -73,14 +101,14 @@ namespace MQTTnet
             if (serverAdapters == null) throw new ArgumentNullException(nameof(serverAdapters));
             if (logger == null) throw new ArgumentNullException(nameof(logger));
 
-            return new MqttServer(serverAdapters, logger.CreateChildLogger());
+            return new MqttServer(serverAdapters, logger);
         }
 
         public IMqttServer CreateMqttServer(IEnumerable<IMqttServerAdapter> serverAdapters)
         {
             if (serverAdapters == null) throw new ArgumentNullException(nameof(serverAdapters));
 
-            return new MqttServer(serverAdapters, DefaultLogger.CreateChildLogger());
+            return new MqttServer(serverAdapters, DefaultLogger);
         }
     }
 }

Source/MQTTnet/Server/IMqttRetainedMessagesManager.cs

@@ -1,12 +1,12 @@
-using System.Collections.Generic;
+using MQTTnet.Diagnostics;
+using System.Collections.Generic;
 using System.Threading.Tasks;
-using MQTTnet.Diagnostics;
 
 namespace MQTTnet.Server
 {
     public interface IMqttRetainedMessagesManager
     {
-        Task Start(IMqttServerOptions options, IMqttNetChildLogger logger);
+        Task Start(IMqttServerOptions options, IMqttNetLogger logger);
 
         Task LoadMessagesAsync();
 

Source/MQTTnet/Server/MqttClientConnection.cs

@@ -3,6 +3,7 @@ using MQTTnet.Client;
 using MQTTnet.Diagnostics;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
+using MQTTnet.Implementations;
 using MQTTnet.Internal;
 using MQTTnet.PacketDispatcher;
 using MQTTnet.Packets;
@@ -15,32 +16,34 @@ using System.Threading.Tasks;
 
 namespace MQTTnet.Server
 {
-    public class MqttClientConnection : IDisposable
+    public sealed class MqttClientConnection : IDisposable
     {
-        private readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
+        readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
-        private readonly MqttPacketDispatcher _packetDispatcher = new MqttPacketDispatcher();
+        readonly MqttPacketDispatcher _packetDispatcher = new MqttPacketDispatcher();
-        private readonly CancellationTokenSource _cancellationToken = new CancellationTokenSource();
+        readonly CancellationTokenSource _cancellationToken = new CancellationTokenSource();
 
-        private readonly IMqttRetainedMessagesManager _retainedMessagesManager;
+        readonly IMqttRetainedMessagesManager _retainedMessagesManager;
-        private readonly MqttClientKeepAliveMonitor _keepAliveMonitor;
+        readonly MqttClientKeepAliveMonitor _keepAliveMonitor;
-        private readonly MqttClientSessionsManager _sessionsManager;
+        readonly MqttClientSessionsManager _sessionsManager;
 
-        private readonly IMqttNetChildLogger _logger;
+        readonly IMqttNetLogger _logger;
-        private readonly IMqttServerOptions _serverOptions;
+        readonly IMqttServerOptions _serverOptions;
 
-        private readonly IMqttChannelAdapter _channelAdapter;
+        readonly IMqttChannelAdapter _channelAdapter;
-        private readonly IMqttDataConverter _dataConverter;
+        readonly IMqttDataConverter _dataConverter;
-        private readonly string _endpoint;
+        readonly string _endpoint;
-        private readonly DateTime _connectedTimestamp;
+        readonly DateTime _connectedTimestamp;
 
-        private Task<MqttClientDisconnectType> _packageReceiverTask;
+        Task<MqttClientDisconnectType> _packageReceiverTask;
-        private DateTime _lastPacketReceivedTimestamp;
+        DateTime _lastPacketReceivedTimestamp;
-        private DateTime _lastNonKeepAlivePacketReceivedTimestamp;
+        DateTime _lastNonKeepAlivePacketReceivedTimestamp;
 
-        private long _receivedPacketsCount;
+        long _receivedPacketsCount;
-        private long _sentPacketsCount = 1; // Start with 1 because the CONNECT packet is not counted anywhere.
+        long _sentPacketsCount = 1; // Start with 1 because the CONNECT packet is not counted anywhere.
-        private long _receivedApplicationMessagesCount;
+        long _receivedApplicationMessagesCount;
-        private long _sentApplicationMessagesCount;
+        long _sentApplicationMessagesCount;
+
+        bool _isTakeover;
 
         public MqttClientConnection(
             MqttConnectPacket connectPacket,
@@ -49,7 +52,7 @@ namespace MQTTnet.Server
             IMqttServerOptions serverOptions,
             MqttClientSessionsManager sessionsManager,
             IMqttRetainedMessagesManager retainedMessagesManager,
-            IMqttNetChildLogger logger)
+            IMqttNetLogger logger)
         {
             Session = session ?? throw new ArgumentNullException(nameof(session));
             _serverOptions = serverOptions ?? throw new ArgumentNullException(nameof(serverOptions));
@@ -64,7 +67,7 @@ namespace MQTTnet.Server
             if (logger == null) throw new ArgumentNullException(nameof(logger));
             _logger = logger.CreateChildLogger(nameof(MqttClientConnection));
 
-            _keepAliveMonitor = new MqttClientKeepAliveMonitor(ConnectPacket.ClientId, StopAsync, _logger);
+            _keepAliveMonitor = new MqttClientKeepAliveMonitor(ConnectPacket.ClientId, () => StopAsync(), _logger);
 
             _connectedTimestamp = DateTime.UtcNow;
             _lastPacketReceivedTimestamp = _connectedTimestamp;
@@ -77,15 +80,21 @@ namespace MQTTnet.Server
 
         public MqttClientSession Session { get; }
 
-        public async Task StopAsync()
+        public bool IsFinalized { get; set; }
+
+        public Task StopAsync(bool isTakeover = false)
         {
+            _isTakeover = isTakeover;
+
             StopInternal();
 
             var task = _packageReceiverTask;
             if (task != null)
             {
-                await task.ConfigureAwait(false);
+                return task;
             }
+
+            return PlatformAbstractionLayer.CompletedTask;
         }
 
         public void ResetStatistics()
@@ -124,7 +133,7 @@ namespace MQTTnet.Server
             return _packageReceiverTask;
         }
 
-        private async Task<MqttClientDisconnectType> RunInternalAsync(MqttConnectionValidatorContext connectionValidatorContext)
+        async Task<MqttClientDisconnectType> RunInternalAsync(MqttConnectionValidatorContext connectionValidatorContext)
         {
             var disconnectType = MqttClientDisconnectType.NotClean;
             try
@@ -243,20 +252,25 @@ namespace MQTTnet.Server
                 _channelAdapter.ReadingPacketStartedCallback = null;
                 _channelAdapter.ReadingPacketCompletedCallback = null;
 
-                _logger.Info("Client '{0}': Session stopped.", ClientId);
+                _logger.Info("Client '{0}': Connection stopped.", ClientId);
 
                 _packageReceiverTask = null;
             }
 
+            if (_isTakeover)
+            {
+                return MqttClientDisconnectType.Takeover;
+            }
+
             return disconnectType;
         }
 
-        private void StopInternal()
+        void StopInternal()
         {
             _cancellationToken.Cancel(false);
         }
 
-        private async Task EnqueueSubscribedRetainedMessagesAsync(ICollection<TopicFilter> topicFilters)
+        async Task EnqueueSubscribedRetainedMessagesAsync(ICollection<TopicFilter> topicFilters)
         {
             var retainedMessages = await _retainedMessagesManager.GetSubscribedMessagesAsync(topicFilters).ConfigureAwait(false);
             foreach (var applicationMessage in retainedMessages)
@@ -265,7 +279,7 @@ namespace MQTTnet.Server
             }
         }
 
-        private async Task HandleIncomingSubscribePacketAsync(MqttSubscribePacket subscribePacket)
+        async Task HandleIncomingSubscribePacketAsync(MqttSubscribePacket subscribePacket)
         {
             // TODO: Let the channel adapter create the packet.
             var subscribeResult = await Session.SubscriptionsManager.SubscribeAsync(subscribePacket, ConnectPacket).ConfigureAwait(false);
@@ -281,14 +295,14 @@ namespace MQTTnet.Server
             await EnqueueSubscribedRetainedMessagesAsync(subscribePacket.TopicFilters).ConfigureAwait(false);
         }
 
-        private async Task HandleIncomingUnsubscribePacketAsync(MqttUnsubscribePacket unsubscribePacket)
+        async Task HandleIncomingUnsubscribePacketAsync(MqttUnsubscribePacket unsubscribePacket)
         {
             // TODO: Let the channel adapter create the packet.
             var unsubscribeResult = await Session.SubscriptionsManager.UnsubscribeAsync(unsubscribePacket).ConfigureAwait(false);
             await SendAsync(unsubscribeResult).ConfigureAwait(false);
         }
 
-        private Task HandleIncomingPublishPacketAsync(MqttPublishPacket publishPacket)
+        Task HandleIncomingPublishPacketAsync(MqttPublishPacket publishPacket)
         {
             Interlocked.Increment(ref _sentApplicationMessagesCount);
 
@@ -313,16 +327,16 @@ namespace MQTTnet.Server
             }
         }
 
-        private Task HandleIncomingPublishPacketWithQoS0Async(MqttPublishPacket publishPacket)
+        Task HandleIncomingPublishPacketWithQoS0Async(MqttPublishPacket publishPacket)
         {
             var applicationMessage = _dataConverter.CreateApplicationMessage(publishPacket);
 
             _sessionsManager.DispatchApplicationMessage(applicationMessage, this);
 
-            return Task.FromResult(0);
+            return PlatformAbstractionLayer.CompletedTask;
         }
 
-        private Task HandleIncomingPublishPacketWithQoS1Async(MqttPublishPacket publishPacket)
+        Task HandleIncomingPublishPacketWithQoS1Async(MqttPublishPacket publishPacket)
         {
             var applicationMessage = _dataConverter.CreateApplicationMessage(publishPacket);
             _sessionsManager.DispatchApplicationMessage(applicationMessage, this);
@@ -331,7 +345,7 @@ namespace MQTTnet.Server
             return SendAsync(pubAckPacket);
         }
 
-        private Task HandleIncomingPublishPacketWithQoS2Async(MqttPublishPacket publishPacket)
+        Task HandleIncomingPublishPacketWithQoS2Async(MqttPublishPacket publishPacket)
         {
             var applicationMessage = _dataConverter.CreateApplicationMessage(publishPacket);
             _sessionsManager.DispatchApplicationMessage(applicationMessage, this);
@@ -345,7 +359,7 @@ namespace MQTTnet.Server
             return SendAsync(pubRecPacket);
         }
 
-        private async Task SendPendingPacketsAsync(CancellationToken cancellationToken)
+        async Task SendPendingPacketsAsync(CancellationToken cancellationToken)
         {
             MqttQueuedApplicationMessage queuedApplicationMessage = null;
             MqttPublishPacket publishPacket = null;
@@ -422,9 +436,6 @@ namespace MQTTnet.Server
                     }
 
                     _logger.Verbose("Queued application message sent (ClientId: {0}).", ClientId);
-
-                    // TODO:
-                    //Interlocked.Increment(ref _sentPacketsCount);
                 }
             }
             catch (Exception exception)
@@ -459,7 +470,7 @@ namespace MQTTnet.Server
             }
         }
 
-        private async Task SendAsync(MqttBasePacket packet)
+        async Task SendAsync(MqttBasePacket packet)
         {
             await _channelAdapter.SendPacketAsync(packet, _serverOptions.DefaultCommunicationTimeout, _cancellationToken.Token).ConfigureAwait(false);
 
@@ -471,12 +482,12 @@ namespace MQTTnet.Server
             }
         }
 
-        private void OnAdapterReadingPacketCompleted()
+        void OnAdapterReadingPacketCompleted()
         {
             _keepAliveMonitor?.Resume();
         }
 
-        private void OnAdapterReadingPacketStarted()
+        void OnAdapterReadingPacketStarted()
         {
             _keepAliveMonitor?.Pause();
         }

Source/MQTTnet/Server/MqttClientKeepAliveMonitor.cs

@@ -1,23 +1,23 @@
-using System;
+using MQTTnet.Diagnostics;
+using MQTTnet.Internal;
+using System;
 using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Diagnostics;
-using MQTTnet.Internal;
 
 namespace MQTTnet.Server
 {
     public class MqttClientKeepAliveMonitor
     {
-        private readonly Stopwatch _lastPacketReceivedTracker = new Stopwatch();
+        readonly Stopwatch _lastPacketReceivedTracker = new Stopwatch();
 
-        private readonly string _clientId;
+        readonly string _clientId;
-        private readonly Func<Task> _keepAliveElapsedCallback;
+        readonly Func<Task> _keepAliveElapsedCallback;
-        private readonly IMqttNetChildLogger _logger;
+        readonly IMqttNetLogger _logger;
 
-        private bool _isPaused;
+        bool _isPaused;
 
-        public MqttClientKeepAliveMonitor(string clientId, Func<Task> keepAliveElapsedCallback, IMqttNetChildLogger logger)
+        public MqttClientKeepAliveMonitor(string clientId, Func<Task> keepAliveElapsedCallback, IMqttNetLogger logger)
         {
             _clientId = clientId ?? throw new ArgumentNullException(nameof(clientId));
             _keepAliveElapsedCallback = keepAliveElapsedCallback ?? throw new ArgumentNullException(nameof(keepAliveElapsedCallback));
@@ -51,7 +51,7 @@ namespace MQTTnet.Server
             _lastPacketReceivedTracker.Restart();
         }
 
-        private async Task RunAsync(int keepAlivePeriod, CancellationToken cancellationToken)
+        async Task RunAsync(int keepAlivePeriod, CancellationToken cancellationToken)
         {
             try
             {

Source/MQTTnet/Server/MqttClientSession.cs

@@ -1,18 +1,18 @@
-using System;
+using MQTTnet.Diagnostics;
+using MQTTnet.Server.Status;
+using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
-using MQTTnet.Diagnostics;
-using MQTTnet.Server.Status;
 
 namespace MQTTnet.Server
 {
     public class MqttClientSession
     {
-        private readonly IMqttNetChildLogger _logger;
+        readonly IMqttNetLogger _logger;
 
-        private readonly DateTime _createdTimestamp = DateTime.UtcNow;
+        readonly DateTime _createdTimestamp = DateTime.UtcNow;
 
-        public MqttClientSession(string clientId, IDictionary<object, object> items, MqttServerEventDispatcher eventDispatcher, IMqttServerOptions serverOptions, IMqttNetChildLogger logger)
+        public MqttClientSession(string clientId, IDictionary<object, object> items, MqttServerEventDispatcher eventDispatcher, IMqttServerOptions serverOptions, IMqttNetLogger logger)
         {
             ClientId = clientId ?? throw new ArgumentNullException(nameof(clientId));
             Items = items ?? throw new ArgumentNullException(nameof(items));
@@ -73,6 +73,7 @@ namespace MQTTnet.Server
             status.ClientId = ClientId;
             status.CreatedTimestamp = _createdTimestamp;
             status.PendingApplicationMessagesCount = ApplicationMessagesQueue.Count;
+            status.Items = Items;
         }
     }
 }

Source/MQTTnet/Server/MqttClientSessionsManager.cs

@@ -16,26 +16,26 @@ namespace MQTTnet.Server
 {
     public class MqttClientSessionsManager : Disposable
     {
-        private readonly AsyncQueue<MqttEnqueuedApplicationMessage> _messageQueue = new AsyncQueue<MqttEnqueuedApplicationMessage>();
+        readonly AsyncQueue<MqttEnqueuedApplicationMessage> _messageQueue = new AsyncQueue<MqttEnqueuedApplicationMessage>();
 
-        private readonly SemaphoreSlim _createConnectionGate = new SemaphoreSlim(1, 1);
+        readonly AsyncLock _createConnectionGate = new AsyncLock();
-        private readonly ConcurrentDictionary<string, MqttClientConnection> _connections = new ConcurrentDictionary<string, MqttClientConnection>();
+        readonly ConcurrentDictionary<string, MqttClientConnection> _connections = new ConcurrentDictionary<string, MqttClientConnection>();
-        private readonly ConcurrentDictionary<string, MqttClientSession> _sessions = new ConcurrentDictionary<string, MqttClientSession>();
+        readonly ConcurrentDictionary<string, MqttClientSession> _sessions = new ConcurrentDictionary<string, MqttClientSession>();
-        private readonly IDictionary<object, object> _serverSessionItems = new ConcurrentDictionary<object, object>();
+        readonly IDictionary<object, object> _serverSessionItems = new ConcurrentDictionary<object, object>();
 
-        private readonly CancellationToken _cancellationToken;
+        readonly CancellationToken _cancellationToken;
-        private readonly MqttServerEventDispatcher _eventDispatcher;
+        readonly MqttServerEventDispatcher _eventDispatcher;
 
-        private readonly IMqttRetainedMessagesManager _retainedMessagesManager;
+        readonly IMqttRetainedMessagesManager _retainedMessagesManager;
-        private readonly IMqttServerOptions _options;
+        readonly IMqttServerOptions _options;
-        private readonly IMqttNetChildLogger _logger;
+        readonly IMqttNetLogger _logger;
 
         public MqttClientSessionsManager(
             IMqttServerOptions options,
             IMqttRetainedMessagesManager retainedMessagesManager,
             CancellationToken cancellationToken,
             MqttServerEventDispatcher eventDispatcher,
-            IMqttNetChildLogger logger)
+            IMqttNetLogger logger)
         {
             _cancellationToken = cancellationToken;
 
@@ -60,9 +60,11 @@ namespace MQTTnet.Server
             }
         }
 
-        public Task HandleClientAsync(IMqttChannelAdapter clientAdapter)
+        public Task HandleClientConnectionAsync(IMqttChannelAdapter clientAdapter)
         {
-            return HandleClientAsync(clientAdapter, _cancellationToken);
+            if (clientAdapter is null) throw new ArgumentNullException(nameof(clientAdapter));
+
+            return HandleClientConnectionAsync(clientAdapter, _cancellationToken);
         }
 
         public Task<IList<IMqttClientStatus>> GetClientStatusAsync()
@@ -155,7 +157,7 @@ namespace MQTTnet.Server
             base.Dispose(disposing);
         }
 
-        private async Task TryProcessQueuedApplicationMessagesAsync(CancellationToken cancellationToken)
+        async Task TryProcessQueuedApplicationMessagesAsync(CancellationToken cancellationToken)
         {
             while (!cancellationToken.IsCancellationRequested)
             {
@@ -173,7 +175,7 @@ namespace MQTTnet.Server
             }
         }
 
-        private async Task TryProcessNextQueuedApplicationMessageAsync(CancellationToken cancellationToken)
+        async Task TryProcessNextQueuedApplicationMessageAsync(CancellationToken cancellationToken)
         {
             try
             {
@@ -207,7 +209,7 @@ namespace MQTTnet.Server
                     applicationMessage = interceptorContext.ApplicationMessage;
                 }
 
-                await _eventDispatcher.HandleApplicationMessageReceivedAsync(sender?.ClientId, applicationMessage).ConfigureAwait(false);
+                await _eventDispatcher.SafeNotifyApplicationMessageReceivedAsync(sender?.ClientId, applicationMessage).ConfigureAwait(false);
 
                 if (applicationMessage.Retain)
                 {
@@ -231,14 +233,14 @@ namespace MQTTnet.Server
             }
         }
 
-        private async Task HandleClientAsync(IMqttChannelAdapter channelAdapter, CancellationToken cancellationToken)
+        async Task HandleClientConnectionAsync(IMqttChannelAdapter channelAdapter, CancellationToken cancellationToken)
         {
             var disconnectType = MqttClientDisconnectType.NotClean;
             string clientId = null;
-            var clientWasConnected = true;
+            var clientWasAuthorized = false;
-
-            MqttConnectPacket connectPacket = null;
 
+            MqttConnectPacket connectPacket;
+            MqttClientConnection clientConnection = null;
             try
             {
                 try
@@ -259,11 +261,8 @@ namespace MQTTnet.Server
 
                 var connectionValidatorContext = await ValidateConnectionAsync(connectPacket, channelAdapter).ConfigureAwait(false);
 
-                clientId = connectPacket.ClientId;
-
                 if (connectionValidatorContext.ReasonCode != MqttConnectReasonCode.Success)
                 {
-                    clientWasConnected = false;
                     // Send failure response here without preparing a session. The result for a successful connect
                     // will be sent from the session itself.
                     var connAckPacket = channelAdapter.PacketFormatterAdapter.DataConverter.CreateConnAckPacket(connectionValidatorContext);
@@ -272,11 +271,13 @@ namespace MQTTnet.Server
                     return;
                 }
 
-                var connection = await CreateConnectionAsync(connectPacket, connectionValidatorContext, channelAdapter).ConfigureAwait(false);
+                clientWasAuthorized = true;
+                clientId = connectPacket.ClientId;
+                clientConnection = await CreateClientConnectionAsync(connectPacket, connectionValidatorContext, channelAdapter).ConfigureAwait(false);
 
-                await _eventDispatcher.HandleClientConnectedAsync(clientId).ConfigureAwait(false);
+                await _eventDispatcher.SafeNotifyClientConnectedAsync(clientId).ConfigureAwait(false);
 
-                disconnectType = await connection.RunAsync(connectionValidatorContext).ConfigureAwait(false);
+                disconnectType = await clientConnection.RunAsync(connectionValidatorContext).ConfigureAwait(false);
             }
             catch (OperationCanceledException)
             {
@@ -287,8 +288,10 @@ namespace MQTTnet.Server
             }
             finally
             {
-                if (clientWasConnected)
+                if (clientWasAuthorized && disconnectType != MqttClientDisconnectType.Takeover)
                 {
+                    // Only cleanup if the client was authorized. If not it will remove the existing connection, session etc.
+                    // This allows to kill connections and sessions from known client IDs.
                     if (clientId != null)
                     {
                         _connections.TryRemove(clientId, out _);
@@ -298,18 +301,23 @@ namespace MQTTnet.Server
                             await DeleteSessionAsync(clientId).ConfigureAwait(false);
                         }
                     }
+                }
 
-                    await TryCleanupChannelAsync(channelAdapter).ConfigureAwait(false);
+                await SafeCleanupChannelAsync(channelAdapter).ConfigureAwait(false);
 
-                    if (clientId != null)
+                if (clientWasAuthorized && clientId != null)
-                    {
+                {
-                        await _eventDispatcher.TryHandleClientDisconnectedAsync(clientId, disconnectType).ConfigureAwait(false);
+                    await _eventDispatcher.SafeNotifyClientDisconnectedAsync(clientId, disconnectType).ConfigureAwait(false);
-                    }
+                }
+
+                if (clientConnection != null)
+                {
+                    clientConnection.IsFinalized = true;
                 }
             }
         }
 
-        private async Task<MqttConnectionValidatorContext> ValidateConnectionAsync(MqttConnectPacket connectPacket, IMqttChannelAdapter channelAdapter)
+        async Task<MqttConnectionValidatorContext> ValidateConnectionAsync(MqttConnectPacket connectPacket, IMqttChannelAdapter channelAdapter)
         {
             var context = new MqttConnectionValidatorContext(connectPacket, channelAdapter, new ConcurrentDictionary<object, object>());
 
@@ -337,17 +345,22 @@ namespace MQTTnet.Server
             return context;
         }
 
-        private async Task<MqttClientConnection> CreateConnectionAsync(MqttConnectPacket connectPacket, MqttConnectionValidatorContext connectionValidatorContext, IMqttChannelAdapter channelAdapter)
+        async Task<MqttClientConnection> CreateClientConnectionAsync(MqttConnectPacket connectPacket, MqttConnectionValidatorContext connectionValidatorContext, IMqttChannelAdapter channelAdapter)
         {
-            await _createConnectionGate.WaitAsync(_cancellationToken).ConfigureAwait(false);
+            using (await _createConnectionGate.WaitAsync(_cancellationToken).ConfigureAwait(false))
-            try
             {
                 var isSessionPresent = _sessions.TryGetValue(connectPacket.ClientId, out var session);
 
                 var isConnectionPresent = _connections.TryGetValue(connectPacket.ClientId, out var existingConnection);
                 if (isConnectionPresent)
                 {
-                    await existingConnection.StopAsync().ConfigureAwait(false);
+                    await existingConnection.StopAsync(true);
+
+                    // TODO: This fixes a race condition with unit test Same_Client_Id_Connect_Disconnect_Event_Order.
+                    // It is not clear where the issue is coming from. The connected event is fired BEFORE the disconnected
+                    // event. This is wrong. It seems that the finally block in HandleClientAsync must be finished before we
+                    // can continue here. Maybe there is a better way to do this.
+                    SpinWait.SpinUntil(() => existingConnection.IsFinalized, TimeSpan.FromSeconds(10));
                 }
 
                 if (isSessionPresent)
@@ -377,13 +390,9 @@ namespace MQTTnet.Server
 
                 return connection;
             }
-            finally
-            {
-                _createConnectionGate.Release();
-            }
         }
 
-        private async Task<MqttApplicationMessageInterceptorContext> InterceptApplicationMessageAsync(MqttClientConnection senderConnection, MqttApplicationMessage applicationMessage)
+        async Task<MqttApplicationMessageInterceptorContext> InterceptApplicationMessageAsync(MqttClientConnection senderConnection, MqttApplicationMessage applicationMessage)
         {
             var interceptor = _options.ApplicationMessageInterceptor;
             if (interceptor == null)
@@ -411,7 +420,7 @@ namespace MQTTnet.Server
             return interceptorContext;
         }
 
-        private async Task TryCleanupChannelAsync(IMqttChannelAdapter channelAdapter)
+        async Task SafeCleanupChannelAsync(IMqttChannelAdapter channelAdapter)
         {
             try
             {

Source/MQTTnet/Server/MqttClientSubscriptionsManager.cs

@@ -1,9 +1,9 @@
-using System;
+using MQTTnet.Packets;
+using MQTTnet.Protocol;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
-using MQTTnet.Packets;
-using MQTTnet.Protocol;
 
 namespace MQTTnet.Server
 {
@@ -67,7 +67,7 @@ namespace MQTTnet.Server
                         _subscriptions[finalTopicFilter.Topic] = finalTopicFilter;
                     }
 
-                    await _eventDispatcher.HandleClientSubscribedTopicAsync(_clientSession.ClientId, finalTopicFilter).ConfigureAwait(false);
+                    await _eventDispatcher.SafeNotifyClientSubscribedTopicAsync(_clientSession.ClientId, finalTopicFilter).ConfigureAwait(false);
                 }
             }
 
@@ -83,7 +83,7 @@ namespace MQTTnet.Server
                 var interceptorContext = await InterceptSubscribeAsync(topicFilter).ConfigureAwait(false);
                 if (!interceptorContext.AcceptSubscription)
                 {
-                   continue;
+                    continue;
                 }
 
                 if (interceptorContext.AcceptSubscription)
@@ -93,7 +93,7 @@ namespace MQTTnet.Server
                         _subscriptions[topicFilter.Topic] = topicFilter;
                     }
 
-                    await _eventDispatcher.HandleClientSubscribedTopicAsync(_clientSession.ClientId, topicFilter).ConfigureAwait(false);
+                    await _eventDispatcher.SafeNotifyClientSubscribedTopicAsync(_clientSession.ClientId, topicFilter).ConfigureAwait(false);
                 }
             }
         }
@@ -131,7 +131,7 @@ namespace MQTTnet.Server
 
             foreach (var topicFilter in unsubscribePacket.TopicFilters)
             {
-                await _eventDispatcher.HandleClientUnsubscribedTopicAsync(_clientSession.ClientId, topicFilter).ConfigureAwait(false);
+                await _eventDispatcher.SafeNotifyClientUnsubscribedTopicAsync(_clientSession.ClientId, topicFilter).ConfigureAwait(false);
             }
 
             return unsubAckPacket;

Source/MQTTnet/Server/MqttRetainedMessagesManager.cs

@@ -1,10 +1,10 @@
-using System;
+using MQTTnet.Diagnostics;
+using MQTTnet.Implementations;
+using MQTTnet.Internal;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
-using MQTTnet.Diagnostics;
-using MQTTnet.Implementations;
-using MQTTnet.Internal;
 
 namespace MQTTnet.Server
 {
@@ -14,10 +14,10 @@ namespace MQTTnet.Server
         private readonly AsyncLock _messagesLock = new AsyncLock();
         private readonly Dictionary<string, MqttApplicationMessage> _messages = new Dictionary<string, MqttApplicationMessage>();
 
-        private IMqttNetChildLogger _logger;
+        private IMqttNetLogger _logger;
         private IMqttServerOptions _options;
 
-        public Task Start(IMqttServerOptions options, IMqttNetChildLogger logger)
+        public Task Start(IMqttServerOptions options, IMqttNetLogger logger)
         {
             if (logger == null) throw new ArgumentNullException(nameof(logger));
             _logger = logger.CreateChildLogger(nameof(MqttRetainedMessagesManager));

Source/MQTTnet/Server/MqttServer.cs

@@ -1,15 +1,15 @@
-using System;
+using MQTTnet.Adapter;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Adapter;
 using MQTTnet.Client.Publishing;
 using MQTTnet.Client.Receiving;
 using MQTTnet.Diagnostics;
 using MQTTnet.Exceptions;
 using MQTTnet.Protocol;
 using MQTTnet.Server.Status;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Server
 {
@@ -17,13 +17,13 @@ namespace MQTTnet.Server
     {
         private readonly MqttServerEventDispatcher _eventDispatcher;
         private readonly ICollection<IMqttServerAdapter> _adapters;
-        private readonly IMqttNetChildLogger _logger;
+        private readonly IMqttNetLogger _logger;
 
         private MqttClientSessionsManager _clientSessionsManager;
         private IMqttRetainedMessagesManager _retainedMessagesManager;
         private CancellationTokenSource _cancellationTokenSource;
 
-        public MqttServer(IEnumerable<IMqttServerAdapter> adapters, IMqttNetChildLogger logger)
+        public MqttServer(IEnumerable<IMqttServerAdapter> adapters, IMqttNetLogger logger)
         {
             if (adapters == null) throw new ArgumentNullException(nameof(adapters));
             _adapters = adapters.ToList();
@@ -194,7 +194,7 @@ namespace MQTTnet.Server
 
         private Task OnHandleClient(IMqttChannelAdapter channelAdapter)
         {
-            return _clientSessionsManager.HandleClientAsync(channelAdapter);
+            return _clientSessionsManager.HandleClientConnectionAsync(channelAdapter);
         }
     }
 }

Source/MQTTnet/Server/MqttServerEventDispatcher.cs

@@ -1,15 +1,15 @@
-using System;
+using MQTTnet.Client.Receiving;
-using System.Threading.Tasks;
-using MQTTnet.Client.Receiving;
 using MQTTnet.Diagnostics;
+using System;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Server
 {
     public class MqttServerEventDispatcher
     {
-        private readonly IMqttNetChildLogger _logger;
+        readonly IMqttNetLogger _logger;
 
-        public MqttServerEventDispatcher(IMqttNetChildLogger logger)
+        public MqttServerEventDispatcher(IMqttNetLogger logger)
         {
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
         }
@@ -24,18 +24,25 @@ namespace MQTTnet.Server
 
         public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler { get; set; }
 
-        public Task HandleClientConnectedAsync(string clientId)
+        public async Task SafeNotifyClientConnectedAsync(string clientId)
         {
-            var handler = ClientConnectedHandler;
+            try
-            if (handler == null)
             {
-                return Task.FromResult(0);
+                var handler = ClientConnectedHandler;
-            }
+                if (handler == null)
+                {
+                    return;
+                }
 
-            return handler.HandleClientConnectedAsync(new MqttServerClientConnectedEventArgs(clientId));
+                await handler.HandleClientConnectedAsync(new MqttServerClientConnectedEventArgs(clientId)).ConfigureAwait(false);
+            }
+            catch (Exception exception)
+            {
+                _logger.Error(exception, "Error while handling custom 'ClientConnected' event.");
+            }
         }
 
-        public async Task TryHandleClientDisconnectedAsync(string clientId, MqttClientDisconnectType disconnectType)
+        public async Task SafeNotifyClientDisconnectedAsync(string clientId, MqttClientDisconnectType disconnectType)
         {
             try
             {
@@ -49,41 +56,62 @@ namespace MQTTnet.Server
             }
             catch (Exception exception)
             {
-                _logger.Error(exception, "Error while handling 'ClientDisconnected' event.");
+                _logger.Error(exception, "Error while handling custom 'ClientDisconnected' event.");
             }
         }
 
-        public Task HandleClientSubscribedTopicAsync(string clientId, TopicFilter topicFilter)
+        public async Task SafeNotifyClientSubscribedTopicAsync(string clientId, TopicFilter topicFilter)
         {
-            var handler = ClientSubscribedTopicHandler;
+            try
-            if (handler == null)
             {
-                return Task.FromResult(0);
+                var handler = ClientSubscribedTopicHandler;
-            }
+                if (handler == null)
+                {
+                    return;
+                }
 
-            return handler.HandleClientSubscribedTopicAsync(new MqttServerClientSubscribedTopicEventArgs(clientId, topicFilter));
+                await handler.HandleClientSubscribedTopicAsync(new MqttServerClientSubscribedTopicEventArgs(clientId, topicFilter)).ConfigureAwait(false);
+            }
+            catch (Exception exception)
+            {
+                _logger.Error(exception, "Error while handling custom 'ClientSubscribedTopic' event.");
+            }
         }
 
-        public Task HandleClientUnsubscribedTopicAsync(string clientId, string topicFilter)
+        public async Task SafeNotifyClientUnsubscribedTopicAsync(string clientId, string topicFilter)
         {
-            var handler = ClientUnsubscribedTopicHandler;
+            try
-            if (handler == null)
             {
-                return Task.FromResult(0);
+                var handler = ClientUnsubscribedTopicHandler;
-            }
+                if (handler == null)
+                {
+                    return;
+                }
 
-            return handler.HandleClientUnsubscribedTopicAsync(new MqttServerClientUnsubscribedTopicEventArgs(clientId, topicFilter));
+                await handler.HandleClientUnsubscribedTopicAsync(new MqttServerClientUnsubscribedTopicEventArgs(clientId, topicFilter)).ConfigureAwait(false);
+            }
+            catch (Exception exception)
+            {
+                _logger.Error(exception, "Error while handling custom 'ClientUnsubscribedTopic' event.");
+            }
         }
 
-        public Task HandleApplicationMessageReceivedAsync(string senderClientId, MqttApplicationMessage applicationMessage)
+        public async Task SafeNotifyApplicationMessageReceivedAsync(string senderClientId, MqttApplicationMessage applicationMessage)
         {
-            var handler = ApplicationMessageReceivedHandler;
+            try
-            if (handler == null)
             {
-                return Task.FromResult(0);
+                var handler = ApplicationMessageReceivedHandler;
-            }
+                if (handler == null)
+                {
+                    return;
+                }
 
-            return handler.HandleApplicationMessageReceivedAsync(new MqttApplicationMessageReceivedEventArgs(senderClientId, applicationMessage));
+                await handler.HandleApplicationMessageReceivedAsync(new MqttApplicationMessageReceivedEventArgs(senderClientId, applicationMessage)).ConfigureAwait(false); ;
+            }
+            catch (Exception exception)
+            {
+                _logger.Error(exception, "Error while handling custom 'ApplicationMessageReceived' event.");
+            }
         }
     }
 }

Source/MQTTnet/Server/Status/IMqttClientStatus.cs

@@ -1,6 +1,6 @@
-using System;
+using MQTTnet.Formatter;
+using System;
 using System.Threading.Tasks;
-using MQTTnet.Formatter;
 
 namespace MQTTnet.Server.Status
 {

Source/MQTTnet/Server/Status/IMqttSessionStatus.cs

@@ -1,12 +1,15 @@
-using System.Threading.Tasks;
+using System.Collections.Generic;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Server.Status
 {
     public interface IMqttSessionStatus
     {
-        string ClientId { get; set; }
+        string ClientId { get; }
 
-        long PendingApplicationMessagesCount { get; set; }
+        long PendingApplicationMessagesCount { get; }
+
+        IDictionary<object, object> Items { get; }
 
         Task ClearPendingApplicationMessagesAsync();
 

Source/MQTTnet/Server/Status/MqttClientStatus.cs

@@ -1,16 +1,16 @@
-using System;
+using MQTTnet.Formatter;
+using System;
 using System.Threading.Tasks;
-using MQTTnet.Formatter;
 
 namespace MQTTnet.Server.Status
 {
     public class MqttClientStatus : IMqttClientStatus
     {
-        private readonly MqttClientConnection _connection;
+        readonly MqttClientConnection _connection;
 
         public MqttClientStatus(MqttClientConnection connection)
         {
-            _connection = connection;
+            _connection = connection ?? throw new ArgumentNullException(nameof(connection));
         }
 
         public string ClientId { get; set; }

Source/MQTTnet/Server/Status/MqttSessionStatus.cs

@@ -1,12 +1,13 @@
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 
 namespace MQTTnet.Server.Status
 {
     public class MqttSessionStatus : IMqttSessionStatus
     {
-        private readonly MqttClientSession _session;
+        readonly MqttClientSession _session;
-        private readonly MqttClientSessionsManager _sessionsManager;
+        readonly MqttClientSessionsManager _sessionsManager;
 
         public MqttSessionStatus(MqttClientSession session, MqttClientSessionsManager sessionsManager)
         {
@@ -20,6 +21,8 @@ namespace MQTTnet.Server.Status
 
         public DateTime CreatedTimestamp { get; set; }
 
+        public IDictionary<object, object> Items { get; set; }
+
         public Task DeleteAsync()
         {
             return _sessionsManager.DeleteSessionAsync(ClientId);

Source/MQTTnet/TopicFilter.cs

@@ -2,6 +2,7 @@
 
 namespace MQTTnet
 {
+    // TODO: Consider renaming to "MqttTopicFilter"
     public class TopicFilter
     {
         public string Topic { get; set; }

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

@@ -6,9 +6,9 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.4.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.5.0" />
-    <PackageReference Include="MSTest.TestAdapter" Version="2.0.0" />
+    <PackageReference Include="MSTest.TestAdapter" Version="2.1.1" />
-    <PackageReference Include="MSTest.TestFramework" Version="2.0.0" />
+    <PackageReference Include="MSTest.TestFramework" Version="2.1.1" />
   </ItemGroup>
 
   <ItemGroup>

Tests/MQTTnet.Benchmarks/LoggerBenchmark.cs

@@ -10,13 +10,13 @@ namespace MQTTnet.Benchmarks
     public class LoggerBenchmark
     {
         private IMqttNetLogger _logger;
-        private IMqttNetChildLogger _childLogger;
+        private IMqttNetLogger _childLogger;
         private bool _useHandler;
 
         [GlobalSetup]
         public void Setup()
         {
-            _logger = new MqttNetLogger("1");
+            _logger = new MqttNetLogger();
             _childLogger = _logger.CreateChildLogger("child");
 
             MqttNetGlobalLogger.LogMessagePublished += OnLogMessagePublished;

Tests/MQTTnet.Benchmarks/MQTTnet.Benchmarks.csproj

@@ -10,8 +10,8 @@
 
   <ItemGroup>
     <PackageReference Include="BenchmarkDotNet" Version="0.12.0" />
-    <PackageReference Include="System.IO.Pipelines" Version="4.5.2" />
+    <PackageReference Include="System.IO.Pipelines" Version="4.7.1" />
-    <PackageReference Include="Microsoft.AspNetCore" Version="2.1.6" />
+    <PackageReference Include="Microsoft.AspNetCore" Version="2.2.0" />
   </ItemGroup>
 
   <ItemGroup>

Tests/MQTTnet.Benchmarks/MqttTcpChannelBenchmark.cs

@@ -1,11 +1,11 @@
 using BenchmarkDotNet.Attributes;
 using MQTTnet.Channel;
+using MQTTnet.Client.Options;
 using MQTTnet.Diagnostics;
 using MQTTnet.Implementations;
 using MQTTnet.Server;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Client.Options;
 
 namespace MQTTnet.Benchmarks
 {
@@ -20,7 +20,7 @@ namespace MQTTnet.Benchmarks
         public void Setup()
         {
             var factory = new MqttFactory();
-            var tcpServer = new MqttTcpServerAdapter(new MqttNetLogger().CreateChildLogger());
+            var tcpServer = new MqttTcpServerAdapter(new MqttNetLogger());
             tcpServer.ClientHandler += args =>
             {
                 _serverChannel =

Tests/MQTTnet.Benchmarks/Program.cs

@@ -9,7 +9,7 @@ namespace MQTTnet.Benchmarks
     {
         public static void Main(string[] args)
         {
-            Console.WriteLine($"MQTTnet - BenchmarkApp.{TargetFrameworkInfoProvider.TargetFramework}");
+            Console.WriteLine($"MQTTnet - BenchmarkApp.{TargetFrameworkProvider.TargetFramework}");
             Console.WriteLine("1 = MessageProcessingBenchmark");
             Console.WriteLine("2 = SerializerBenchmark");
             Console.WriteLine("3 = LoggerBenchmark");

Tests/MQTTnet.Core.Tests/CrossPlatformSocket_Tests.cs

@@ -0,0 +1,74 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Implementations;
+using System;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Tests
+{
+    [TestClass]
+    public class CrossPlatformSocket_Tests
+    {
+        [TestMethod]
+        public async Task Connect_Send_Receive()
+        {
+            var crossPlatformSocket = new CrossPlatformSocket();
+            await crossPlatformSocket.ConnectAsync("www.google.de", 80, CancellationToken.None);
+
+            var requestBuffer = Encoding.UTF8.GetBytes("GET / HTTP/1.1\r\nHost: www.google.de\r\n\r\n");
+            await crossPlatformSocket.SendAsync(new ArraySegment<byte>(requestBuffer), System.Net.Sockets.SocketFlags.None);
+
+            var buffer = new byte[1024];
+            var length = await crossPlatformSocket.ReceiveAsync(new ArraySegment<byte>(buffer), System.Net.Sockets.SocketFlags.None);
+            crossPlatformSocket.Dispose();
+
+            var responseText = Encoding.UTF8.GetString(buffer, 0, length);
+
+            Assert.IsTrue(responseText.Contains("HTTP/1.1 200 OK"));
+        }
+
+        [TestMethod]
+        public async Task Try_Connect_Invalid_Host()
+        {
+            var crossPlatformSocket = new CrossPlatformSocket();
+
+            var cancellationToken = new CancellationTokenSource(TimeSpan.FromSeconds(3));
+            cancellationToken.Token.Register(() => crossPlatformSocket.Dispose());
+
+            await crossPlatformSocket.ConnectAsync("www.google.de", 1234, CancellationToken.None);
+        }
+
+        //[TestMethod]
+        //public async Task Use_Disconnected_Socket()
+        //{
+        //    var crossPlatformSocket = new CrossPlatformSocket();
+
+        //    await crossPlatformSocket.ConnectAsync("www.google.de", 80);
+
+        //    var requestBuffer = Encoding.UTF8.GetBytes("GET /wrong_uri HTTP/1.1\r\nConnection: close\r\n\r\n");
+        //    await crossPlatformSocket.SendAsync(new ArraySegment<byte>(requestBuffer), System.Net.Sockets.SocketFlags.None);
+
+        //    var buffer = new byte[64000];
+        //    var length = await crossPlatformSocket.ReceiveAsync(new ArraySegment<byte>(buffer), System.Net.Sockets.SocketFlags.None);
+
+        //    await Task.Delay(500);
+
+        //    await crossPlatformSocket.SendAsync(new ArraySegment<byte>(requestBuffer), System.Net.Sockets.SocketFlags.None);
+        //}
+
+        [TestMethod]
+        public async Task Set_Options()
+        {
+            var crossPlatformSocket = new CrossPlatformSocket();
+
+            Assert.IsFalse(crossPlatformSocket.ReuseAddress);
+            crossPlatformSocket.ReuseAddress = true;
+            Assert.IsTrue(crossPlatformSocket.ReuseAddress);
+
+            Assert.IsFalse(crossPlatformSocket.NoDelay);
+            crossPlatformSocket.NoDelay = true;
+            Assert.IsTrue(crossPlatformSocket.NoDelay);
+        }
+    }
+}

Tests/MQTTnet.Core.Tests/LowLevelMqttClient_Tests.cs

@@ -0,0 +1,111 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Client.Options;
+using MQTTnet.LowLevelClient;
+using MQTTnet.Packets;
+using MQTTnet.Protocol;
+using MQTTnet.Tests.Mockups;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Tests
+{
+    [TestClass]
+    public class LowLevelMqttClient_Tests
+    {
+        public TestContext TestContext { get; set; }
+
+        [TestMethod]
+        public async Task Connect_And_Disconnect()
+        {
+            using (var testEnvironment = new TestEnvironment(TestContext))
+            {
+                var server = await testEnvironment.StartServerAsync();
+
+                var factory = new MqttFactory();
+                var lowLevelClient = factory.CreateLowLevelMqttClient();
+
+                await lowLevelClient.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).Build(), CancellationToken.None);
+
+                await lowLevelClient.DisconnectAsync(CancellationToken.None);
+            }
+        }
+
+        [TestMethod]
+        public async Task Authenticate()
+        {
+            using (var testEnvironment = new TestEnvironment(TestContext))
+            {
+                var server = await testEnvironment.StartServerAsync();
+
+                var factory = new MqttFactory();
+                var lowLevelClient = factory.CreateLowLevelMqttClient();
+
+                await lowLevelClient.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).Build(), CancellationToken.None);
+
+                var receivedPacket = await Authenticate(lowLevelClient).ConfigureAwait(false);
+
+                await lowLevelClient.DisconnectAsync(CancellationToken.None).ConfigureAwait(false);
+
+                Assert.IsNotNull(receivedPacket);
+                Assert.AreEqual(MqttConnectReturnCode.ConnectionAccepted, receivedPacket.ReturnCode);
+            }
+        }
+
+        [TestMethod]
+        public async Task Subscribe()
+        {
+            using (var testEnvironment = new TestEnvironment(TestContext))
+            {
+                var server = await testEnvironment.StartServerAsync();
+
+                var factory = new MqttFactory();
+                var lowLevelClient = factory.CreateLowLevelMqttClient();
+
+                await lowLevelClient.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).Build(), CancellationToken.None);
+
+                await Authenticate(lowLevelClient).ConfigureAwait(false);
+
+                var receivedPacket = await Subscribe(lowLevelClient, "a").ConfigureAwait(false);
+
+                await lowLevelClient.DisconnectAsync(CancellationToken.None).ConfigureAwait(false);
+
+                Assert.IsNotNull(receivedPacket);
+                Assert.AreEqual(MqttSubscribeReturnCode.SuccessMaximumQoS0, receivedPacket.ReturnCodes[0]);
+            }
+        }
+
+        async Task<MqttConnAckPacket> Authenticate(ILowLevelMqttClient client)
+        {
+            await client.SendAsync(new MqttConnectPacket()
+            {
+                CleanSession = true,
+                ClientId = TestContext.TestName,
+                Username = "user",
+                Password = Encoding.UTF8.GetBytes("pass")
+            },
+            CancellationToken.None).ConfigureAwait(false);
+
+            return await client.ReceiveAsync(CancellationToken.None).ConfigureAwait(false) as MqttConnAckPacket;
+        }
+
+        async Task<MqttSubAckPacket> Subscribe(ILowLevelMqttClient client, string topic)
+        {
+            await client.SendAsync(new MqttSubscribePacket
+            {
+                PacketIdentifier = 1,
+                TopicFilters = new List<TopicFilter>
+                {
+                    new TopicFilter
+                    {
+                        Topic = topic
+                    }
+                }
+            },
+            CancellationToken.None).ConfigureAwait(false);
+
+            return await client.ReceiveAsync(CancellationToken.None).ConfigureAwait(false) as MqttSubAckPacket;
+        }
+    }
+}

Tests/MQTTnet.Core.Tests/MQTTnet.Tests.csproj

@@ -6,9 +6,9 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="MSTest.TestAdapter" Version="2.0.0" />
+    <PackageReference Include="MSTest.TestAdapter" Version="2.1.1" />
-    <PackageReference Include="MSTest.TestFramework" Version="2.0.0" />
+    <PackageReference Include="MSTest.TestFramework" Version="2.1.1" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.4.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.5.0" />
   </ItemGroup>
 
   <ItemGroup>

Tests/MQTTnet.Core.Tests/ManagedMqttClient_Tests.cs

@@ -69,7 +69,7 @@ namespace MQTTnet.Tests
                     .WithTcpServer("localhost", testEnvironment.ServerPort)
                     .WithWillMessage(willMessage);
                 var dyingClient = testEnvironment.CreateClient();
-                var dyingManagedClient = new ManagedMqttClient(dyingClient, testEnvironment.ClientLogger.CreateChildLogger());
+                var dyingManagedClient = new ManagedMqttClient(dyingClient, testEnvironment.ClientLogger);
                 await dyingManagedClient.StartAsync(new ManagedMqttClientOptionsBuilder()
                     .WithClientOptions(clientOptions)
                     .Build());
@@ -96,7 +96,7 @@ namespace MQTTnet.Tests
 
                 var server = await testEnvironment.StartServerAsync();
 
-                var managedClient = new ManagedMqttClient(testEnvironment.CreateClient(), new MqttNetLogger().CreateChildLogger());
+                var managedClient = new ManagedMqttClient(testEnvironment.CreateClient(), new MqttNetLogger());
                 var clientOptions = new MqttClientOptionsBuilder()
                     .WithTcpServer("localhost", testEnvironment.ServerPort);
 
@@ -128,7 +128,7 @@ namespace MQTTnet.Tests
 
                 var server = await testEnvironment.StartServerAsync();
 
-                var managedClient = new ManagedMqttClient(testEnvironment.CreateClient(), new MqttNetLogger().CreateChildLogger());
+                var managedClient = new ManagedMqttClient(testEnvironment.CreateClient(), new MqttNetLogger());
                 var clientOptions = new MqttClientOptionsBuilder()
                     .WithTcpServer("localhost", testEnvironment.ServerPort);
                 var storage = new ManagedMqttClientTestStorage();
@@ -351,7 +351,7 @@ namespace MQTTnet.Tests
             managedOptions.ConnectionCheckInterval = connectionCheckInterval ?? TimeSpan.FromSeconds(0.1);
 
             var managedClient =
-              new ManagedMqttClient(underlyingClient ?? testEnvironment.CreateClient(), new MqttNetLogger().CreateChildLogger());
+              new ManagedMqttClient(underlyingClient ?? testEnvironment.CreateClient(), new MqttNetLogger());
 
             var connected = GetConnectedTask(managedClient);
 

Tests/MQTTnet.Core.Tests/Mockups/TestClientWrapper.cs

@@ -1,6 +1,4 @@
-using System.Threading;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
 using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
@@ -10,10 +8,12 @@ using MQTTnet.Client.Publishing;
 using MQTTnet.Client.Receiving;
 using MQTTnet.Client.Subscribing;
 using MQTTnet.Client.Unsubscribing;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Tests.Mockups
 {
-    public class TestClientWrapper : IMqttClient
+    public sealed class TestClientWrapper : IMqttClient
     {
         public TestClientWrapper(IMqttClient implementation, TestContext testContext)
         {
@@ -22,40 +22,42 @@ namespace MQTTnet.Tests.Mockups
         }
 
         public IMqttClient Implementation { get; }
+
         public TestContext TestContext { get; }
 
         public bool IsConnected => Implementation.IsConnected;
 
         public IMqttClientOptions Options => Implementation.Options;
 
-        public IMqttClientConnectedHandler ConnectedHandler { get => Implementation.ConnectedHandler; set => Implementation.ConnectedHandler = value; }
+        public IMqttClientConnectedHandler ConnectedHandler
-        public IMqttClientDisconnectedHandler DisconnectedHandler { get => Implementation.DisconnectedHandler; set => Implementation.DisconnectedHandler = value; }
+        {
-        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler { get => Implementation.ApplicationMessageReceivedHandler; set => Implementation.ApplicationMessageReceivedHandler = value; }
+            get => Implementation.ConnectedHandler;
+            set => Implementation.ConnectedHandler = value;
+        }
+
+        public IMqttClientDisconnectedHandler DisconnectedHandler
+        {
+            get => Implementation.DisconnectedHandler;
+            set => Implementation.DisconnectedHandler = value;
+        }
+
+        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler
+        {
+            get => Implementation.ApplicationMessageReceivedHandler;
+            set => Implementation.ApplicationMessageReceivedHandler = value;
+        }
 
         public Task<MqttClientAuthenticateResult> ConnectAsync(IMqttClientOptions options, CancellationToken cancellationToken)
         {
-            switch (options)
+            if (TestContext != null)
             {
-                case MqttClientOptionsBuilder builder:
+                var clientOptions = (MqttClientOptions)options;
-                    {
+
-                        var existingClientId = builder.Build().ClientId;
+                var existingClientId = clientOptions.ClientId;
-                        if (existingClientId != null && !existingClientId.StartsWith(TestContext.TestName))
+                if (existingClientId != null && !existingClientId.StartsWith(TestContext.TestName))
-                        {
+                {
-                            builder.WithClientId(TestContext.TestName + existingClientId);
+                    clientOptions.ClientId = TestContext.TestName + existingClientId;
-                        }
+                }
-                    }
-                    break;
-                case MqttClientOptions op:
-                    {
-                        var existingClientId = op.ClientId;
-                        if (existingClientId != null && !existingClientId.StartsWith(TestContext.TestName))
-                        {
-                            op.ClientId = TestContext.TestName + existingClientId;
-                        }
-                    }
-                    break;
-                default:
-                    break;
             }
 
             return Implementation.ConnectAsync(options, cancellationToken);
@@ -81,7 +83,7 @@ namespace MQTTnet.Tests.Mockups
             return Implementation.SendExtendedAuthenticationExchangeDataAsync(data, cancellationToken);
         }
 
-        public Task<Client.Subscribing.MqttClientSubscribeResult> SubscribeAsync(MqttClientSubscribeOptions options, CancellationToken cancellationToken)
+        public Task<MqttClientSubscribeResult> SubscribeAsync(MqttClientSubscribeOptions options, CancellationToken cancellationToken)
         {
             return Implementation.SubscribeAsync(options, cancellationToken);
         }

Tests/MQTTnet.Core.Tests/Mockups/TestEnvironment.cs

@@ -1,27 +1,27 @@
-using System;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
 using MQTTnet.Client.Options;
 using MQTTnet.Diagnostics;
 using MQTTnet.Internal;
 using MQTTnet.Server;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Tests.Mockups
 {
-    public class TestEnvironment : Disposable
+    public sealed class TestEnvironment : Disposable
     {
-        private readonly MqttFactory _mqttFactory = new MqttFactory();
+        readonly MqttFactory _mqttFactory = new MqttFactory();
-        private readonly List<IMqttClient> _clients = new List<IMqttClient>();
+        readonly List<IMqttClient> _clients = new List<IMqttClient>();
-        private readonly IMqttNetLogger _serverLogger = new MqttNetLogger("server");
+        readonly IMqttNetLogger _serverLogger = new MqttNetLogger("server");
-        private readonly IMqttNetLogger _clientLogger = new MqttNetLogger("client");
+        readonly IMqttNetLogger _clientLogger = new MqttNetLogger("client");
 
-        private readonly List<string> _serverErrors = new List<string>();
+        readonly List<string> _serverErrors = new List<string>();
-        private readonly List<string> _clientErrors = new List<string>();
+        readonly List<string> _clientErrors = new List<string>();
 
-        private readonly List<Exception> _exceptions = new List<Exception>();
+        readonly List<Exception> _exceptions = new List<Exception>();
 
         public IMqttServer Server { get; private set; }
 
@@ -37,36 +37,42 @@ namespace MQTTnet.Tests.Mockups
 
         public TestContext TestContext { get; }
 
+        public TestEnvironment() : this(null)
+        {
+        }
+
         public TestEnvironment(TestContext testContext)
         {
+            TestContext = testContext;
+
             _serverLogger.LogMessagePublished += (s, e) =>
             {
-                if (e.TraceMessage.Level == MqttNetLogLevel.Error)
+                if (e.LogMessage.Level == MqttNetLogLevel.Error)
                 {
                     lock (_serverErrors)
                     {
-                        _serverErrors.Add(e.TraceMessage.ToString());
+                        _serverErrors.Add(e.LogMessage.ToString());
                     }
                 }
             };
 
             _clientLogger.LogMessagePublished += (s, e) =>
             {
-                lock (_clientErrors)
+                if (e.LogMessage.Level == MqttNetLogLevel.Error)
                 {
-                    if (e.TraceMessage.Level == MqttNetLogLevel.Error)
+                    lock (_clientErrors)
                     {
-                        _clientErrors.Add(e.TraceMessage.ToString());
+                        _clientErrors.Add(e.LogMessage.ToString());
                     }
                 }
             };
-            TestContext = testContext;
         }
 
         public IMqttClient CreateClient()
         {
             var client = _mqttFactory.CreateMqttClient(_clientLogger);
             _clients.Add(client);
+
             return new TestClientWrapper(client, TestContext);
         }
 
@@ -90,15 +96,17 @@ namespace MQTTnet.Tests.Mockups
 
         public Task<IMqttClient> ConnectClientAsync()
         {
-            return ConnectClientAsync(new MqttClientOptionsBuilder() );
+            return ConnectClientAsync(new MqttClientOptionsBuilder());
         }
 
         public async Task<IMqttClient> ConnectClientAsync(MqttClientOptionsBuilder options)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 
+            options = options.WithTcpServer("localhost", ServerPort);
+
             var client = CreateClient();
-            await client.ConnectAsync(options.WithTcpServer("localhost", ServerPort).Build());
+            await client.ConnectAsync(options.Build());
 
             return client;
         }
@@ -150,6 +158,7 @@ namespace MQTTnet.Tests.Mockups
                     throw new Exception($"{_exceptions.Count} exceptions tracked.\r\n" + string.Join(Environment.NewLine, _exceptions));
                 }
             }
+
             base.Dispose(disposing);
         }
 

Tests/MQTTnet.Core.Tests/Mockups/TestLogger.cs

@@ -1,20 +1,15 @@
-using System;
+using MQTTnet.Diagnostics;
-using MQTTnet.Diagnostics;
+using System;
 
 namespace MQTTnet.Tests.Mockups
 {
-    public class TestLogger : IMqttNetLogger, IMqttNetChildLogger
+    public class TestLogger : IMqttNetLogger
     {
         public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
-        IMqttNetChildLogger IMqttNetLogger.CreateChildLogger(string source)
+        public IMqttNetLogger CreateChildLogger(string source)
         {
-            return new MqttNetChildLogger(this, source);
+            return new TestLogger();
-        }
-
-        IMqttNetChildLogger IMqttNetChildLogger.CreateChildLogger(string source)
-        {
-            return new MqttNetChildLogger(this, source);
         }
 
         public void Verbose(string message, params object[] parameters)
@@ -36,5 +31,10 @@ namespace MQTTnet.Tests.Mockups
         public void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception)
         {
         }
+
+        public void Publish(MqttNetLogLevel logLevel, string message, object[] parameters, Exception exception)
+        {
+            throw new NotImplementedException();
+        }
     }
 }

Tests/MQTTnet.Core.Tests/Mockups/TestMqttCommunicationAdapterFactory.cs

@@ -13,7 +13,7 @@ namespace MQTTnet.Tests.Mockups
             _adapter = adapter;
         }
 
-        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetChildLogger logger)
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger)
         {
             return _adapter;
         }

Tests/MQTTnet.Core.Tests/Mockups/TestServerWrapper.cs

@@ -1,16 +1,16 @@
-using System;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System.Collections.Generic;
-using System.Threading;
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client.Publishing;
 using MQTTnet.Client.Receiving;
 using MQTTnet.Server;
 using MQTTnet.Server.Status;
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Tests.Mockups
 {
-    public class TestServerWrapper : IMqttServer
+    public sealed class TestServerWrapper : IMqttServer
     {
         public TestServerWrapper(IMqttServer implementation, TestContext testContext, TestEnvironment testEnvironment)
         {
@@ -22,16 +22,50 @@ namespace MQTTnet.Tests.Mockups
         public IMqttServer Implementation { get; }
         public TestContext TestContext { get; }
         public TestEnvironment TestEnvironment { get; }
-        public IMqttServerStartedHandler StartedHandler { get => Implementation.StartedHandler; set => Implementation.StartedHandler = value; }
+
-        public IMqttServerStoppedHandler StoppedHandler { get => Implementation.StoppedHandler; set => Implementation.StoppedHandler = value; }
+        public IMqttServerStartedHandler StartedHandler
-        public IMqttServerClientConnectedHandler ClientConnectedHandler { get => Implementation.ClientConnectedHandler; set => Implementation.ClientConnectedHandler = value; }
+        {
-        public IMqttServerClientDisconnectedHandler ClientDisconnectedHandler { get => Implementation.ClientDisconnectedHandler; set => Implementation.ClientDisconnectedHandler = value; }
+            get => Implementation.StartedHandler;
-        public IMqttServerClientSubscribedTopicHandler ClientSubscribedTopicHandler { get => Implementation.ClientSubscribedTopicHandler; set => Implementation.ClientSubscribedTopicHandler = value; }
+            set => Implementation.StartedHandler = value;
-        public IMqttServerClientUnsubscribedTopicHandler ClientUnsubscribedTopicHandler { get => Implementation.ClientUnsubscribedTopicHandler; set => Implementation.ClientUnsubscribedTopicHandler = value; }
+        }
+
+        public IMqttServerStoppedHandler StoppedHandler
+        {
+            get => Implementation.StoppedHandler;
+            set => Implementation.StoppedHandler = value;
+        }
+
+        public IMqttServerClientConnectedHandler ClientConnectedHandler
+        {
+            get => Implementation.ClientConnectedHandler;
+            set => Implementation.ClientConnectedHandler = value;
+        }
+
+        public IMqttServerClientDisconnectedHandler ClientDisconnectedHandler
+        {
+            get => Implementation.ClientDisconnectedHandler;
+            set => Implementation.ClientDisconnectedHandler = value;
+        }
+
+        public IMqttServerClientSubscribedTopicHandler ClientSubscribedTopicHandler
+        {
+            get => Implementation.ClientSubscribedTopicHandler;
+            set => Implementation.ClientSubscribedTopicHandler = value;
+        }
+
+        public IMqttServerClientUnsubscribedTopicHandler ClientUnsubscribedTopicHandler
+        {
+            get => Implementation.ClientUnsubscribedTopicHandler;
+            set => Implementation.ClientUnsubscribedTopicHandler = value;
+        }
 
         public IMqttServerOptions Options => Implementation.Options;
 
-        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler { get => Implementation.ApplicationMessageReceivedHandler; set => Implementation.ApplicationMessageReceivedHandler = value; }
+        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler
+        {
+            get => Implementation.ApplicationMessageReceivedHandler;
+            set => Implementation.ApplicationMessageReceivedHandler = value;
+        }
 
         public Task ClearRetainedApplicationMessagesAsync()
         {
@@ -60,22 +94,14 @@ namespace MQTTnet.Tests.Mockups
 
         public Task StartAsync(IMqttServerOptions options)
         {
-            switch (options)
+            if (TestContext != null)
             {
-                case MqttServerOptionsBuilder builder:
+                var serverOptions = (MqttServerOptions)options;
-                    if (builder.Build().ConnectionValidator == null)
+
-                    {
+                if (serverOptions.ConnectionValidator == null)
-                        builder.WithConnectionValidator(ConnectionValidator);
+                {
-                    }
+                    serverOptions.ConnectionValidator = new MqttServerConnectionValidatorDelegate(ConnectionValidator);
-                    break;
+                }
-                case MqttServerOptions op:
-                    if (op.ConnectionValidator == null)
-                    {
-                        op.ConnectionValidator = new MqttServerConnectionValidatorDelegate(ConnectionValidator);
-                    }
-                    break;
-                default:
-                    break;
             }
 
             return Implementation.StartAsync(options);
@@ -85,7 +111,7 @@ namespace MQTTnet.Tests.Mockups
         {
             if (!ctx.ClientId.StartsWith(TestContext.TestName))
             {
-                TestEnvironment.TrackException(new InvalidOperationException($"invalid client connected '{ctx.ClientId}'"));
+                TestEnvironment.TrackException(new InvalidOperationException($"Invalid client ID used ({ctx.ClientId}). It must start with UnitTest name."));
                 ctx.ReasonCode = Protocol.MqttConnectReasonCode.ClientIdentifierNotValid;
             }
         }

Tests/MQTTnet.Core.Tests/MqttApplicationMessage_Tests.cs

@@ -0,0 +1,32 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Extensions;
+using MQTTnet.Packets;
+using System.Collections.Generic;
+
+namespace MQTTnet.Tests
+{
+    [TestClass]
+    public class MqttApplicationMessage_Tests
+    {
+        [TestMethod]
+        public void GetUserProperty_Test()
+        {
+            var message = new MqttApplicationMessage
+            {
+                UserProperties = new List<MqttUserProperty>
+                {
+                    new MqttUserProperty("foo", "bar"),
+                    new MqttUserProperty("value", "1011"),
+                    new MqttUserProperty("CASE", "insensitive")
+                }
+            };
+
+            Assert.AreEqual("bar", message.GetUserProperty("foo"));
+            //Assert.AreEqual(1011, message.GetUserProperty<int>("value"));
+            Assert.AreEqual(null, message.GetUserProperty("case"));
+            Assert.AreEqual(null, message.GetUserProperty("nonExists"));
+            //Assert.AreEqual(null, message.GetUserProperty<int?>("nonExists"));
+            //Assert.ThrowsException<InvalidOperationException>(() => message.GetUserProperty<int>("nonExists"));
+        }
+    }
+}

Tests/MQTTnet.Core.Tests/MqttClientOptionsBuilder_Tests.cs

@@ -0,0 +1,22 @@
+using System.Linq;
+using System.Text;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Client.Options;
+using MQTTnet.Extensions;
+
+namespace MQTTnet.Tests
+{
+    [TestClass]
+    public class MqttClientOptionsBuilder_Tests
+    {
+        [TestMethod]
+        public void WithConnectionUri_Credential_Test()
+        {
+            var options = new MqttClientOptionsBuilder()
+                .WithConnectionUri("mqtt://user:password@127.0.0.1")
+                .Build();
+            Assert.AreEqual("user", options.Credentials.Username);
+            Assert.IsTrue(Encoding.UTF8.GetBytes("password").SequenceEqual(options.Credentials.Password));
+        }
+    }
+}

Tests/MQTTnet.Core.Tests/MqttClient_Tests.cs

@@ -1,9 +1,3 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Net.Sockets;
-using System.Threading;
-using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
 using MQTTnet.Client.Connecting;
@@ -14,6 +8,12 @@ using MQTTnet.Exceptions;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
 using MQTTnet.Tests.Mockups;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Sockets;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Tests
 {
@@ -78,7 +78,7 @@ namespace MQTTnet.Tests
                     }
                 });
 
-                client2.UseApplicationMessageReceivedHandler(async c =>{ await client2.PublishAsync("reply", null, MqttQualityOfServiceLevel.AtLeastOnce); });
+                client2.UseApplicationMessageReceivedHandler(async c => { await client2.PublishAsync("reply", null, MqttQualityOfServiceLevel.AtLeastOnce); });
 
                 await client1.PublishAsync("request", null, MqttQualityOfServiceLevel.AtLeastOnce);
 
@@ -558,6 +558,8 @@ namespace MQTTnet.Tests
                     clients.Add(await testEnvironment.ConnectClientAsync(new MqttClientOptionsBuilder().WithClientId("a")));
                 }
 
+                await Task.Delay(500);
+
                 var clientStatus = await testEnvironment.Server.GetClientStatusAsync();
                 var sessionStatus = await testEnvironment.Server.GetSessionStatusAsync();
 
@@ -583,7 +585,7 @@ namespace MQTTnet.Tests
                 var sendClient = await testEnvironment.ConnectClientAsync();
                 await sendClient.PublishAsync("x", "1");
 
-                await Task.Delay(100);
+                await Task.Delay(250);
 
                 Assert.AreEqual("1", receivedPayload);
             }

Tests/MQTTnet.Core.Tests/MqttFactory_Tests.cs

@@ -18,13 +18,13 @@ namespace MQTTnet.Tests
             // This test compares
             // 1. correct logID
             var logId = "logId";
-            string invalidLogId = null;
+            var hasInvalidLogId = false;
 
             // 2. if the total log calls are the same for global and local
             //var globalLogCount = 0;
             var localLogCount = 0;
 
-            var logger = new MqttNetLogger(logId);
+            var logger = new MqttNetLogger(null, logId);
 
             // TODO: This is commented out because it is affected by other tests.
             //// we have a theoretical bug here if a concurrent test is also logging
@@ -42,9 +42,9 @@ namespace MQTTnet.Tests
 
             logger.LogMessagePublished += (s, e) =>
             {
-                if (e.TraceMessage.LogId != logId)
+                if (e.LogMessage.LogId != logId)
                 {
-                    invalidLogId = e.TraceMessage.LogId;
+                    hasInvalidLogId = true;
                 }
 
                 Interlocked.Increment(ref localLogCount);
@@ -72,7 +72,9 @@ namespace MQTTnet.Tests
                 //MqttNetGlobalLogger.LogMessagePublished -= globalLog;
             }
 
-            Assert.IsNull(invalidLogId);
+            await Task.Delay(500);
+
+            Assert.IsFalse(hasInvalidLogId);
             Assert.AreNotEqual(0, localLogCount);
         }
     }

Tests/MQTTnet.Core.Tests/MqttKeepAliveMonitor_Tests.cs

@@ -1,12 +1,12 @@
-using System;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System.Collections.Generic;
-using System.Threading;
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
 using MQTTnet.Server;
 using MQTTnet.Server.Status;
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Tests
 {
@@ -23,7 +23,7 @@ namespace MQTTnet.Tests
                     counter++;
                     return Task.CompletedTask;
                 },
-                new MqttNetLogger().CreateChildLogger());
+                new MqttNetLogger());
 
             Assert.AreEqual(0, counter);
 
@@ -46,7 +46,7 @@ namespace MQTTnet.Tests
                     counter++;
                     return Task.CompletedTask;
                 },
-                new MqttNetLogger().CreateChildLogger());
+                new MqttNetLogger());
 
             Assert.AreEqual(0, counter);
 

Tests/MQTTnet.Core.Tests/MqttNetLogger_Tests.cs

@@ -0,0 +1,67 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Diagnostics;
+
+namespace MQTTnet.Tests
+{
+    [TestClass]
+    public class MqttNetLogger_Tests
+    {
+        [TestMethod]
+        public void Root_Log_Messages()
+        {
+            var logger = new MqttNetLogger();
+
+            var logMessagesCount = 0;
+
+            logger.LogMessagePublished += (s, e) =>
+            {
+                logMessagesCount++;
+            };
+
+            logger.Verbose("Verbose");
+            logger.Info("Info");
+            logger.Warning(null, "Warning");
+            logger.Error(null, "Error");
+
+            Assert.AreEqual(4, logMessagesCount);
+        }
+
+        [TestMethod]
+        public void Bubbling_Log_Messages()
+        {
+            var logger = new MqttNetLogger();
+            var childLogger = logger.CreateChildLogger("Source1");
+
+            var logMessagesCount = 0;
+
+            logger.LogMessagePublished += (s, e) =>
+            {
+                logMessagesCount++;
+            };
+
+            childLogger.Verbose("Verbose");
+            childLogger.Info("Info");
+            childLogger.Warning(null, "Warning");
+            childLogger.Error(null, "Error");
+
+            Assert.AreEqual(4, logMessagesCount);
+        }
+
+        [TestMethod]
+        public void Set_Custom_Log_ID()
+        {
+            var logger = new MqttNetLogger(null, "logId");
+            var childLogger = logger.CreateChildLogger("Source1");
+
+            logger.LogMessagePublished += (s, e) =>
+            {
+                Assert.AreEqual("logId", e.LogMessage.LogId);
+            };
+
+            childLogger.Verbose("Verbose");
+            childLogger.Info("Info");
+            childLogger.Warning(null, "Warning");
+            childLogger.Error(null, "Error");
+        }
+    }
+}

Tests/MQTTnet.Core.Tests/MqttTcpChannel_Tests.cs

@@ -1,10 +1,10 @@
-using System;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Implementations;
+using System;
 using System.Net;
 using System.Net.Sockets;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Implementations;
 
 namespace MQTTnet.Tests
 {
@@ -15,7 +15,7 @@ namespace MQTTnet.Tests
         public async Task Dispose_Channel_While_Used()
         {
             var ct = new CancellationTokenSource();
-            var serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+            var serverSocket = new CrossPlatformSocket(AddressFamily.InterNetwork);
 
             try
             {
@@ -28,18 +28,18 @@ namespace MQTTnet.Tests
                 {
                     while (!ct.IsCancellationRequested)
                     {
-                        var client = await PlatformAbstractionLayer.AcceptAsync(serverSocket);
+                        var client = await serverSocket.AcceptAsync();
                         var data = new byte[] { 128 };
-                        await PlatformAbstractionLayer.SendAsync(client, new ArraySegment<byte>(data), SocketFlags.None);
+                        await client.SendAsync(new ArraySegment<byte>(data), SocketFlags.None);
                     }
                 }, ct.Token);
 
-                var clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+                var clientSocket = new CrossPlatformSocket(AddressFamily.InterNetwork);
-                await PlatformAbstractionLayer.ConnectAsync(clientSocket, IPAddress.Loopback, 50001);
+                await clientSocket.ConnectAsync("localhost", 50001, CancellationToken.None);
 
                 await Task.Delay(100, ct.Token);
 
-                var tcpChannel = new MqttTcpChannel(new NetworkStream(clientSocket, true), "test", null);
+                var tcpChannel = new MqttTcpChannel(clientSocket.GetStream(), "test", null);
 
                 var buffer = new byte[1];
                 await tcpChannel.ReadAsync(buffer, 0, 1, ct.Token);

Tests/MQTTnet.Core.Tests/Server_Tests.cs

@@ -904,14 +904,13 @@ namespace MQTTnet.Tests
 
                 await testEnvironment.StartServerAsync(serverOptions);
 
-
                 var connectingFailedException = await Assert.ThrowsExceptionAsync<MqttConnectingFailedException>(() => testEnvironment.ConnectClientAsync());
                 Assert.AreEqual(MqttClientConnectResultCode.NotAuthorized, connectingFailedException.ResultCode);
             }
         }
 
+        Dictionary<string, bool> _connected;
 
-        private Dictionary<string, bool> _connected;
         private void ConnectionValidationHandler(MqttConnectionValidatorContext eventArgs)
         {
             if (_connected.ContainsKey(eventArgs.ClientId))
@@ -919,6 +918,7 @@ namespace MQTTnet.Tests
                 eventArgs.ReasonCode = MqttConnectReasonCode.BadUserNameOrPassword;
                 return;
             }
+
             _connected[eventArgs.ClientId] = true;
             eventArgs.ReasonCode = MqttConnectReasonCode.Success;
             return;
@@ -1016,7 +1016,7 @@ namespace MQTTnet.Tests
         [TestMethod]
         public async Task Same_Client_Id_Connect_Disconnect_Event_Order()
         {
-            using (var testEnvironment = new TestEnvironment(TestContext))
+            using (var testEnvironment = new TestEnvironment())
             {
                 var server = await testEnvironment.StartServerAsync(new MqttServerOptionsBuilder());
 
@@ -1038,11 +1038,11 @@ namespace MQTTnet.Tests
                     }
                 });
 
-                var clientOptions = new MqttClientOptionsBuilder()
+                var clientOptionsBuilder = new MqttClientOptionsBuilder()
-                    .WithClientId("same_id");
+                    .WithClientId(Guid.NewGuid().ToString());
 
                 // c
-                var c1 = await testEnvironment.ConnectClientAsync(clientOptions);
+                var c1 = await testEnvironment.ConnectClientAsync(clientOptionsBuilder);
 
                 await Task.Delay(500);
 
@@ -1051,7 +1051,13 @@ namespace MQTTnet.Tests
 
                 // dc
                 // Connect client with same client ID. Should disconnect existing client.
-                var c2 = await testEnvironment.ConnectClientAsync(clientOptions);
+                var c2 = await testEnvironment.ConnectClientAsync(clientOptionsBuilder);
+
+                await Task.Delay(500);
+
+                flow = string.Join(string.Empty, events);
+
+                Assert.AreEqual("cdc", flow);
 
                 c2.UseApplicationMessageReceivedHandler(_ =>
                 {
@@ -1061,15 +1067,10 @@ namespace MQTTnet.Tests
                     }
                 });
 
-                c2.SubscribeAsync("topic").Wait();
+                await c2.SubscribeAsync("topic");
-
-                await Task.Delay(500);
-
-                flow = string.Join(string.Empty, events);
-                Assert.AreEqual("cdc", flow);
 
                 // r
-                c2.PublishAsync("topic").Wait();
+                await c2.PublishAsync("topic");
 
                 await Task.Delay(500);
 
@@ -1149,15 +1150,15 @@ namespace MQTTnet.Tests
             {
                 await testEnvironment.StartServerAsync(new MqttServerOptionsBuilder().WithDefaultCommunicationTimeout(TimeSpan.FromSeconds(1)));
 
-                var client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+                var client = new CrossPlatformSocket(AddressFamily.InterNetwork);
-                await PlatformAbstractionLayer.ConnectAsync(client, "localhost", testEnvironment.ServerPort);
+                await client.ConnectAsync("localhost", testEnvironment.ServerPort, CancellationToken.None);
 
                 // Don't send anything. The server should close the connection.
                 await Task.Delay(TimeSpan.FromSeconds(3));
 
                 try
                 {
-                    var receivedBytes = await PlatformAbstractionLayer.ReceiveAsync(client, new ArraySegment<byte>(new byte[10]), SocketFlags.Partial);
+                    var receivedBytes = await client.ReceiveAsync(new ArraySegment<byte>(new byte[10]), SocketFlags.Partial);
                     if (receivedBytes == 0)
                     {
                         return;
@@ -1180,17 +1181,17 @@ namespace MQTTnet.Tests
 
                 // Send an invalid packet and ensure that the server will close the connection and stay in a waiting state
                 // forever. This is security related.
-                var client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+                var client = new CrossPlatformSocket(AddressFamily.InterNetwork);
-                await PlatformAbstractionLayer.ConnectAsync(client, "localhost", testEnvironment.ServerPort);
+                await client.ConnectAsync("localhost", testEnvironment.ServerPort, CancellationToken.None);
 
                 var buffer = Encoding.UTF8.GetBytes("Garbage");
-                client.Send(buffer, buffer.Length, SocketFlags.None);
+                await client.SendAsync(new ArraySegment<byte>(buffer), SocketFlags.None);
 
                 await Task.Delay(TimeSpan.FromSeconds(3));
 
                 try
                 {
-                    var receivedBytes = await PlatformAbstractionLayer.ReceiveAsync(client, new ArraySegment<byte>(new byte[10]), SocketFlags.Partial);
+                    var receivedBytes = await client.ReceiveAsync(new ArraySegment<byte>(new byte[10]), SocketFlags.Partial);
                     if (receivedBytes == 0)
                     {
                         return;

Tests/MQTTnet.Core.Tests/Session_Tests.cs

@@ -1,10 +1,11 @@
-using System.Text;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
 using MQTTnet.Client.Subscribing;
 using MQTTnet.Server;
 using MQTTnet.Tests.Mockups;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
 
 namespace MQTTnet.Tests
 {
@@ -42,7 +43,7 @@ namespace MQTTnet.Tests
                 string receivedPayload = null;
 
                 var client = await testEnvironment.ConnectClientAsync();
-                client.UseApplicationMessageReceivedHandler(delegate(MqttApplicationMessageReceivedEventArgs args)
+                client.UseApplicationMessageReceivedHandler(delegate (MqttApplicationMessageReceivedEventArgs args)
                 {
                     receivedPayload = args.ApplicationMessage.ConvertPayloadToString();
                 });
@@ -59,5 +60,29 @@ namespace MQTTnet.Tests
                 Assert.AreEqual("Hello World", receivedPayload);
             }
         }
+
+        [TestMethod]
+        public async Task Get_Session_Items_In_Status()
+        {
+            using (var testEnvironment = new TestEnvironment(TestContext))
+            {
+                var serverOptions = new MqttServerOptionsBuilder()
+                    .WithConnectionValidator(delegate (MqttConnectionValidatorContext context)
+                    {
+                        // Don't validate anything. Just set some session items.
+                        context.SessionItems["can_subscribe_x"] = true;
+                        context.SessionItems["default_payload"] = "Hello World";
+                    });
+
+                await testEnvironment.StartServerAsync(serverOptions);
+
+                var client = await testEnvironment.ConnectClientAsync();
+
+                var sessionStatus = await testEnvironment.Server.GetSessionStatusAsync();
+                var session = sessionStatus.First();
+
+                Assert.AreEqual(true, session.Items["can_subscribe_x"]);
+            }
+        }
     }
 }

Tests/MQTTnet.TestApp.AspNetCore2/MQTTnet.TestApp.AspNetCore2.csproj

@@ -10,8 +10,8 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore" Version="2.1.6" />
+    <PackageReference Include="Microsoft.AspNetCore" Version="2.2.0" />
-    <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="2.1.1" />
+    <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="2.2.0" />
   </ItemGroup>
 
   <ItemGroup>

Tests/MQTTnet.TestApp.NetCore/Program.cs

@@ -17,7 +17,7 @@ namespace MQTTnet.TestApp.NetCore
     {
         public static void Main()
         {
-            Console.WriteLine($"MQTTnet - TestApp.{TargetFrameworkInfoProvider.TargetFramework}");
+            Console.WriteLine($"MQTTnet - TestApp.{TargetFrameworkProvider.TargetFramework}");
             Console.WriteLine("1 = Start client");
             Console.WriteLine("2 = Start server");
             Console.WriteLine("3 = Start performance test");

Tests/MQTTnet.TestApp.UniversalWindows/MQTTnet.TestApp.UniversalWindows.csproj

@@ -147,7 +147,7 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.NETCore.UniversalWindowsPlatform">
-      <Version>6.2.8</Version>
+      <Version>6.2.10</Version>
     </PackageReference>
     <PackageReference Include="Microsoft.Toolkit.Uwp.UI.Controls">
       <Version>4.0.0</Version>

Tests/MQTTnet.TestApp.UniversalWindows/MainPage.xaml.cs

@@ -1,12 +1,4 @@
-using System;
+using MQTTnet.Client;
-using System.Collections.Concurrent;
-using System.Collections.ObjectModel;
-using System.Text;
-using System.Threading.Tasks;
-using Windows.Security.Cryptography.Certificates;
-using Windows.UI.Core;
-using Windows.UI.Xaml;
-using MQTTnet.Client;
 using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
 using MQTTnet.Client.Options;
@@ -14,14 +6,22 @@ using MQTTnet.Diagnostics;
 using MQTTnet.Exceptions;
 using MQTTnet.Extensions.ManagedClient;
 using MQTTnet.Extensions.Rpc;
+using MQTTnet.Extensions.WebSocket4Net;
 using MQTTnet.Formatter;
 using MQTTnet.Implementations;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
 using MQTTnet.Server.Status;
+using System;
+using System.Collections.Concurrent;
+using System.Collections.ObjectModel;
+using System.Text;
+using System.Threading.Tasks;
+using Windows.Security.Cryptography.Certificates;
+using Windows.UI.Core;
+using Windows.UI.Xaml;
 using MqttClientConnectedEventArgs = MQTTnet.Client.Connecting.MqttClientConnectedEventArgs;
 using MqttClientDisconnectedEventArgs = MQTTnet.Client.Disconnecting.MqttClientDisconnectedEventArgs;
-using MQTTnet.Extensions.WebSocket4Net;
 
 namespace MQTTnet.TestApp.UniversalWindows
 {
@@ -198,16 +198,26 @@ namespace MQTTnet.TestApp.UniversalWindows
 
         private void OnDisconnected(MqttClientDisconnectedEventArgs e)
         {
-            _traceMessages.Enqueue(new MqttNetLogMessage("", DateTime.Now, -1,
+            _traceMessages.Enqueue(new MqttNetLogMessage
-                "", MqttNetLogLevel.Info, "! DISCONNECTED EVENT FIRED", null));
+            {
+                Timestamp = DateTime.UtcNow,
+                ThreadId = -1,
+                Level = MqttNetLogLevel.Info,
+                Message = "! DISCONNECTED EVENT FIRED",
+            });
 
             Task.Run(UpdateLogAsync);
         }
 
         private void OnConnected(MqttClientConnectedEventArgs e)
         {
-            _traceMessages.Enqueue(new MqttNetLogMessage("", DateTime.Now, -1,
+            _traceMessages.Enqueue(new MqttNetLogMessage
-                "", MqttNetLogLevel.Info, "! CONNECTED EVENT FIRED", null));
+            {
+                Timestamp = DateTime.UtcNow,
+                ThreadId = -1,
+                Level = MqttNetLogLevel.Info,
+                Message = "! CONNECTED EVENT FIRED",
+            });
 
             Task.Run(UpdateLogAsync);
         }