Refactor code.

Update python runtime for MQTTnet.Server.
Update README.md
2026-10-15 00:15:15 +08:00 · 2020-04-10 10:53:17 +02:00 · 2020-04-08 22:01:20 +02:00 · 2020-04-07 12:22:16 +02:00 · 2020-04-05 15:43:16 +02:00 · 2020-04-04 23:36:58 +02:00
201 changed files with 5153 additions and 2039 deletions
@@ -0,0 +1,46 @@
+---
+name: Bug report
+about: Create a report to help us improve.
+title: ''
+labels: 'bug'
+assignees: ''
+
+---
+
+### Describe the bug
+A clear and concise description of what the bug is.
+
+### Which project is your bug related to?
+<!-- Remove the items which don't apply from the following list -->
+- Client
+- ManagedClient
+- MQTTnet.Server standalone
+- Server
+- Generic
+
+### To Reproduce
+Steps to reproduce the behavior:
+1. Using this version of MQTTnet '...'.
+2. Run this code '....'.
+3. With these arguments '....'.
+4. See error.
+
+### Expected behavior
+A clear and concise description of what you expected to happen.
+
+### Screenshots
+If applicable, add screenshots to help explain your problem.
+
+### Additional context / logging
+Add any other context about the problem here.
+Include debugging or logging information here:
+
+```batch
+\\ Put your logging output here.
+```
+### Code example
+ Please provide full code examples below where possible to make it easier for the developers to check your issues.
+ 
+```csharp
+\\ Put your code here.
+```
@@ -0,0 +1,19 @@
+---
+name: Custom issue template
+about: Do you have a question related to the project? Use this template.
+title: ''
+labels: 'question'
+assignees: ''
+
+---
+
+### Describe your question
+A clear and concise description of what you want to know.
+
+### Which project is your question related to?
+<!-- Remove the items which don't apply from the following list -->
+- Client
+- ManagedClient
+- MQTTnet.Server standalone
+- Server
+- Generic
@@ -0,0 +1,29 @@
+---
+name: Feature request
+about: Suggest an idea for this project.
+title: ''
+labels: 'feature-request'
+assignees: ''
+
+---
+
+### Describe the feature request
+Is your feature request related to a problem? Please describe.
+A clear and concise description of what the problem is. Example. I'm am trying to do [...] but [...]
+
+### Which project is your feature request related to?
+<!-- Remove the items which don't apply from the following list -->
+- Client
+- ManagedClient
+- MQTTnet.Server standalone
+- Server
+- Generic
+
+### Describe the solution you'd like
+A clear and concise description of what you want to happen.
+
+### Describe alternatives you've considered
+A clear and concise description of any alternative solutions or features you've considered.
+
+### Additional context
+Add any other context or screenshots about the feature request here.
@@ -292,3 +292,5 @@ __pycache__/
 *.map

 /Tests/MQTTnet.TestApp.NetCore/RetainedMessages.json
+
+Build/NuGet/
@@ -8,18 +8,19 @@
    <license type="file">LICENSE</license>
    <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
    <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
+    <icon>images\Logo_128x128.png</icon>
    <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.Http.Connections" version="1.0.3"  />
-      <dependency id="Microsoft.AspNetCore.WebSockets" version="2.1.1" />
-      <dependency id="Microsoft.Extensions.Hosting.Abstractions" version="2.1.1" />
+      <dependency id="Microsoft.AspNetCore.Connections.Abstractions" version="3.1.3" />
+      <dependency id="Microsoft.AspNetCore.Http.Connections" version="1.1.0"  />
+      <dependency id="Microsoft.AspNetCore.WebSockets" version="2.2.1" />
+      <dependency id="Microsoft.Extensions.Hosting.Abstractions" version="3.1.3" />
    </dependencies>
  </metadata>

@@ -27,6 +28,9 @@
    <!-- License -->
    <file src="..\LICENSE" />

+    <!-- Images -->
+    <file src="..\Images\Logo_128x128.png" target="images\" />
+
    <!-- .NET Standard 2.0 -->
    <file src="..\Source\MQTTnet.AspNetCore\bin\Release\netstandard2.0\MQTTnet.AspNetCore.*" target="lib\netstandard2.0\"/>
  </files>
@@ -8,10 +8,11 @@
    <license type="file">LICENSE</license>
    <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
    <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
+    <icon>images\Logo_128x128.png</icon>
    <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" />
@@ -22,6 +23,9 @@
    <!-- License -->
    <file src="..\LICENSE" />

+    <!-- Images -->
+    <file src="..\Images\Logo_128x128.png" target="images\" />
+
    <!-- .NET Standard 1.3 -->
    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard1.3\MQTTnet.Extensions.ManagedClient.*" target="lib\netstandard1.3\"/>

@@ -8,10 +8,11 @@
    <license type="file">LICENSE</license>
    <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
    <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
+    <icon>images\Logo_128x128.png</icon>
    <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" />
@@ -22,6 +23,9 @@
    <!-- License -->
    <file src="..\LICENSE" />

+    <!-- Images -->
+    <file src="..\Images\Logo_128x128.png" target="images\" />
+
    <!-- .NET Standard 1.3 -->
    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard1.3\MQTTnet.Extensions.Rpc.*" target="lib\netstandard1.3\"/>

@@ -8,10 +8,11 @@
    <license type="file">LICENSE</license>
    <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
    <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
+    <icon>images\Logo_128x128.png</icon>
    <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" />
@@ -22,6 +23,9 @@
    <!-- License -->
    <file src="..\LICENSE" />

+    <!-- Images -->
+    <file src="..\Images\Logo_128x128.png" target="images\" />
+
    <!-- .NET Standard 1.3 -->
    <file src="..\Source\MQTTnet.Extensions.WebSocket4Net\bin\Release\netstandard1.3\MQTTnet.Extensions.WebSocket4Net.*" target="lib\netstandard1.3\"/>

@@ -8,10 +8,11 @@
    <license type="file">LICENSE</license>
    <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
    <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
+    <icon>images\Logo_128x128.png</icon>
    <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">
@@ -33,6 +34,9 @@
    <!-- License -->
    <file src="..\LICENSE" />

+    <!-- Images -->
+    <file src="..\Images\Logo_128x128.png" target="images\" />
+
    <!-- .NET Standard 1.3 -->
    <file src="..\Source\MQTTnet\bin\Release\netstandard1.3\MQTTnet.*" target="lib\netstandard1.3\"/>

@@ -8,27 +8,32 @@
    <license type="file">LICENSE</license>
    <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
    <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
+    <icon>images\Logo_128x128.png</icon>
    <requireLicenseAcceptance>false</requireLicenseAcceptance>
    <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>
-* [Core] Fixed issues in MQTTv5 message encoding and decoding.
-* [Core] Added extension method to allow usage of _WebSocket4Net_ in clients to fix issues with AWS and Xamarin.
-* [Core] Fixed usage of wrong data type for passwords (string -> byte[]).
-* [Core] Fixed an _ObjectDisposedException_ when sending data using a WebSocket channel.
-* [Core] Performance optimizations.
-* [Client] Added support for extended authentication exchange.
-* [Client] Exposed MQTTv5 CONNACK values to client.
-* [Client] Added _MqttClientSubscribeOptionsBuilder_.
-* [Client] The disconnected handler is now executed in a new task to prevent deadlocks when reconnecting etc. (thanks to @lizziebeans).
-* [Client] Converted option _DualMode_ into nullable boolean to preserve original value and avoid exceptions in IPv4 only networks (thanks to @lavaflo).
-* [Server] Exposed _ClientCertificateRequired_ and _CheckCertificateRevocation_ at TLS options.
-* [Server] Exposed client certificate at client connection validator.
-* [Server] The subscription interceptor now supports altering the entire topic filter.
-* [Server] Exposed more properties to the connection validator context.
-* [MQTTnet.Server] Added authentication support via Python script file.
-* [MQTTnet.Server] Migrated the result of connection validations to _ReasonCode_ (MQTTv5) instead of _ReturnCode_ (MQTTv3 only) (BREAKING CHANGE!).
+* [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).
+* [Client] Support PublishAsync with QoS 1 and QoS 2 from within an ApplicationMessageReceivedHandler (#648, #587, thanks to @PSanetra).
+* [Client] Fixed MqttCommunicationTimedOutExceptions, caused by a long running ApplicationMessageReceivedHandler, which blocked MQTT packets from being processed (#829, thanks to @PSanetra).
+* [ManagedClient] Added builder class for MqttClientUnsubscribeOptions (thanks to @dominikviererbe).
+* [ManagedClient] Added support for persisted sessions (thansk to @PMExtra).
+* [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.
+* [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 interceptor for unsubscriptions.
    </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">
@@ -44,7 +49,7 @@
        <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>
@@ -53,6 +58,9 @@
    <!-- License -->
    <file src="..\LICENSE" />

+    <!-- Images -->
+    <file src="..\Images\Logo_128x128.png" target="images\" />
+
    <!-- .NET Standard 1.3 -->
    <file src="..\Source\MQTTnet\bin\Release\netstandard1.3\MQTTnet.*" target="lib\netstandard1.3\"/>
    
@@ -70,4 +78,4 @@

    <!-- Everything above .NET Framework 4.6.1 will use the binaries from 4.6.1. -->
  </files>
-</package>
+</package>
@@ -12,6 +12,17 @@ Write-Host "Nuget version    = $nugetVersion"
 Write-Host "MSBuild path     = $msbuild"
 Write-Host

+Invoke-WebRequest -Uri "https://dist.nuget.org/win-x86-commandline/latest/nuget.exe" -OutFile "nuget.exe"
+
+.\nuget.exe restore ..\MQTTnet.sln
+
+# Build and execute tests
+&$msbuild ..\Tests\MQTTnet.Core.Tests\MQTTnet.Tests.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netcoreapp3.1" /verbosity:m
+&$msbuild ..\Tests\MQTTnet.AspNetCore.Tests\MQTTnet.AspNetCore.Tests.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netcoreapp3.1" /verbosity:m
+
+vstest.console.exe ..\Tests\MQTTnet.Core.Tests\bin\Release\netcoreapp3.1\MQTTnet.Tests.dll
+vstest.console.exe ..\Tests\MQTTnet.AspNetCore.Tests\bin\Release\netcoreapp3.1\MQTTnet.AspNetCore.Tests.dll
+
 # Build the core library
 &$msbuild ..\Source\MQTTnet\MQTTnet.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net452" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet\MQTTnet.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net461" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
@@ -43,56 +54,8 @@ Write-Host
 &$msbuild ..\Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="uap10.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"

-####################################################################
-
-# Build MQTTnet.Server Portable
-&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion
-
-$source = "..\Source\MQTTnet.Server\bin\Release\netcoreapp2.2\publish"
-$destination = "..\Source\MQTTnet.Server\bin\MQTTnet.Server-Portable-v$nugetVersion.zip"
-If(Test-path $destination) {Remove-item $destination}
- Add-Type -assembly "system.io.compression.filesystem"
-[io.compression.zipfile]::CreateFromDirectory($source, $destination) 
-
-####################################################################
-
-# Build MQTTnet.Server Linux-x64
-&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion --self-contained --runtime linux-x64 
-
-$source = "..\Source\MQTTnet.Server\bin\Release\netcoreapp2.2\linux-x64\publish"
-$destination = "..\Source\MQTTnet.Server\bin\MQTTnet.Server-Linux-x64-v$nugetVersion.zip"
-If(Test-path $destination) {Remove-item $destination}
- Add-Type -assembly "system.io.compression.filesystem"
-[io.compression.zipfile]::CreateFromDirectory($source, $destination) 
-
-####################################################################
-
-# Build MQTTnet.Server Linux-ARM
-&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion --self-contained --runtime linux-arm 
-
-$source = "..\Source\MQTTnet.Server\bin\Release\netcoreapp2.2\linux-ARM\publish"
-$destination = "..\Source\MQTTnet.Server\bin\MQTTnet.Server-Linux-ARM-v$nugetVersion.zip"
-If(Test-path $destination) {Remove-item $destination}
- Add-Type -assembly "system.io.compression.filesystem"
-[io.compression.zipfile]::CreateFromDirectory($source, $destination) 
-
-####################################################################
-
-# Build MQTTnet.Server Windows-x64
-&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion --self-contained --runtime win-x64
-
-$source = "..\Source\MQTTnet.Server\bin\Release\netcoreapp2.2\win-x64\publish"
-$destination = "..\Source\MQTTnet.Server\bin\MQTTnet.Server-Windows-x64-v$nugetVersion.zip"
-If(Test-path $destination) {Remove-item $destination}
- Add-Type -assembly "system.io.compression.filesystem"
-[io.compression.zipfile]::CreateFromDirectory($source, $destination) 
-
-####################################################################
-
 # Create NuGet packages.

-Invoke-WebRequest -Uri "https://dist.nuget.org/win-x86-commandline/latest/nuget.exe" -OutFile "nuget.exe"
-
 Remove-Item .\NuGet -Force -Recurse -ErrorAction SilentlyContinue

 Copy-Item MQTTnet.AspNetCore.nuspec -Destination MQTTnet.AspNetCore.nuspec.old -Force
@@ -105,16 +68,62 @@ Copy-Item MQTTnet.Extensions.WebSocket4Net.nuspec -Destination MQTTnet.Extension
 (Get-Content MQTTnet.Extensions.WebSocket4Net.nuspec) -replace '\$nugetVersion', $nugetVersion | Set-Content MQTTnet.Extensions.WebSocket4Net.nuspec

 New-Item -ItemType Directory -Force -Path .\NuGet
-.\nuget.exe pack MQTTnet.nuspec -Verbosity detailed -Symbols -OutputDir "NuGet" -Version $nugetVersion
-.\nuget.exe pack MQTTnet.NETStandard.nuspec -Verbosity detailed -Symbols -OutputDir "NuGet" -Version $nugetVersion
-.\nuget.exe pack MQTTnet.AspNetCore.nuspec -Verbosity detailed -Symbols -OutputDir "NuGet" -Version $nugetVersion
-.\nuget.exe pack MQTTnet.Extensions.Rpc.nuspec -Verbosity detailed -Symbols -OutputDir "NuGet" -Version $nugetVersion
-.\nuget.exe pack MQTTnet.Extensions.ManagedClient.nuspec -Verbosity detailed -Symbols -OutputDir "NuGet" -Version $nugetVersion
-.\nuget.exe pack MQTTnet.Extensions.WebSocket4Net.nuspec -Verbosity detailed -Symbols -OutputDir "NuGet" -Version $nugetVersion
+.\nuget.exe pack MQTTnet.nuspec -Verbosity detailed -Symbols -SymbolPackageFormat snupkg -OutputDir "NuGet" -Version $nugetVersion
+.\nuget.exe pack MQTTnet.NETStandard.nuspec -Verbosity detailed -Symbols -SymbolPackageFormat snupkg -OutputDir "NuGet" -Version $nugetVersion
+.\nuget.exe pack MQTTnet.AspNetCore.nuspec -Verbosity detailed -Symbols -SymbolPackageFormat snupkg -OutputDir "NuGet" -Version $nugetVersion
+.\nuget.exe pack MQTTnet.Extensions.Rpc.nuspec -Verbosity detailed -Symbols -SymbolPackageFormat snupkg -OutputDir "NuGet" -Version $nugetVersion
+.\nuget.exe pack MQTTnet.Extensions.ManagedClient.nuspec -Verbosity detailed -Symbols -SymbolPackageFormat snupkg -OutputDir "NuGet" -Version $nugetVersion
+.\nuget.exe pack MQTTnet.Extensions.WebSocket4Net.nuspec -Verbosity detailed -Symbols -SymbolPackageFormat snupkg -OutputDir "NuGet" -Version $nugetVersion

 Move-Item MQTTnet.AspNetCore.nuspec.old -Destination MQTTnet.AspNetCore.nuspec -Force
 Move-Item MQTTnet.Extensions.Rpc.nuspec.old -Destination MQTTnet.Extensions.Rpc.nuspec -Force
 Move-Item MQTTnet.Extensions.ManagedClient.nuspec.old -Destination MQTTnet.Extensions.ManagedClient.nuspec -Force
 Move-Item MQTTnet.Extensions.WebSocket4Net.nuspec.old -Destination MQTTnet.Extensions.WebSocket4Net.nuspec -Force

-Remove-Item "nuget.exe" -Force -Recurse -ErrorAction SilentlyContinue
+Remove-Item "nuget.exe" -Force -Recurse -ErrorAction SilentlyContinue
+
+####################################################################
+
+# Build MQTTnet.Server Portable
+&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion
+
+$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\publish"
+$destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Portable-v$nugetVersion.zip"
+If(Test-path $destination) {Remove-item $destination}
+ Add-Type -assembly "system.io.compression.filesystem"
+[io.compression.zipfile]::CreateFromDirectory($source, $destination) 
+
+####################################################################
+
+# Build MQTTnet.Server Linux-x64
+&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion --self-contained --runtime linux-x64 
+
+$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\linux-x64\publish"
+$destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Linux-x64-v$nugetVersion.zip"
+If(Test-path $destination) {Remove-item $destination}
+ Add-Type -assembly "system.io.compression.filesystem"
+[io.compression.zipfile]::CreateFromDirectory($source, $destination) 
+
+####################################################################
+
+# Build MQTTnet.Server Linux-ARM
+&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion --self-contained --runtime linux-arm 
+
+$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\linux-ARM\publish"
+$destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Linux-ARM-v$nugetVersion.zip"
+If(Test-path $destination) {Remove-item $destination}
+ Add-Type -assembly "system.io.compression.filesystem"
+[io.compression.zipfile]::CreateFromDirectory($source, $destination) 
+
+####################################################################
+
+# Build MQTTnet.Server Windows-x64
+&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion --self-contained --runtime win-x64
+
+$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\win-x64\publish"
+$destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Windows-x64-v$nugetVersion.zip"
+If(Test-path $destination) {Remove-item $destination}
+ Add-Type -assembly "system.io.compression.filesystem"
+[io.compression.zipfile]::CreateFromDirectory($source, $destination) 
+
+####################################################################
@@ -7,7 +7,7 @@ foreach ($file in $files)
 {
 	Write-Host "Uploading: " $file

-	.\nuget.exe push $file.Fullname $apiKey -NoSymbols -Source https://api.nuget.org/v3/index.json
+	.\nuget.exe push $file.Fullname $apiKey -Source https://api.nuget.org/v3/index.json
 }

 Remove-Item "nuget.exe" -Force -Recurse -ErrorAction SilentlyContinue
@@ -1,9 +1,9 @@
 # Import codeSigningKey.pfx
 In order to import the key for code signing on a new developer machine use the following command within the VS developer command line:

-> sn –i codeSigningKey.pfx VS_KEY_EFCA4C5B6DFD4B4F
+sn –i .\codeSigningKey.pfx VS_KEY_62CA73019ED23333

 The container name may be different.

 # Check if the assembly has a strong name
-> sn -vf MQTTnet.dll
+sn -vf MQTTnet.dll
@@ -0,0 +1,239 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="210mm"
+   height="297mm"
+   viewBox="0 0 210 297"
+   version="1.1"
+   id="svg8"
+   inkscape:version="0.92.4 (5da689c313, 2019-01-14)"
+   sodipodi:docname="MQTT.svg">
+  <defs
+     id="defs2">
+    <filter
+       inkscape:label="Blur Double"
+       inkscape:menu="Blurs"
+       inkscape:menu-tooltip="Overlays two copies with different blur amounts and modifiable blend and composite"
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+         stdDeviation="5"
+         result="fbSourceGraphic"
+         id="feGaussianBlur3793" />
+      <feGaussianBlur
+         stdDeviation="0.01"
+         in="SourceGraphic"
+         result="result1"
+         id="feGaussianBlur3795" />
+      <feComposite
+         in2="result1"
+         operator="arithmetic"
+         in="fbSourceGraphic"
+         k2="0.5"
+         k3="0.5"
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+      <feBlend
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+         mode="normal"
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+         id="feBlend3799" />
+    </filter>
+  </defs>
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+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
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+     inkscape:pageshadow="2"
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+       style="fill:#ce0000;fill-opacity:0.60591131;stroke-width:2.26591563"
+       d="M 464.66602,532.89453 542.01562,669.92969 1595.373,1648.873 a 995.76487,866.17896 0 0 1 14.0293,-12.6835 995.76487,866.17896 0 0 1 23.6231,-17.4727 z"
+       id="rect3806-2"
+       inkscape:connector-curvature="0"
+       transform="scale(0.26458333)"
+       inkscape:export-xdpi="2.6500001"
+       inkscape:export-ydpi="2.6500001" />
+    <text
+       xml:space="preserve"
+       style="font-style:normal;font-weight:normal;font-size:10.58333302px;line-height:1.25;font-family:sans-serif;letter-spacing:0px;word-spacing:0px;fill:#000000;fill-opacity:1;stroke:none;stroke-width:0.26458332"
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+       inkscape:export-xdpi="2.6500001"
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+         sodipodi:role="line"
+         id="tspan3772"
+         x="102.34985"
+         y="320.75201"
+         style="font-size:141.1111145px;fill:#ffffff;stroke-width:0.26458332">MQTT</tspan></text>
+    <ellipse
+       ry="33.94323"
+       rx="39.021355"
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+       cx="124.47787"
+       id="ellipse3768"
+       style="fill:#d40000;stroke-width:0.06901014"
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+       inkscape:export-ydpi="2.6500001" />
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+       style="fill:#d40000;stroke-width:0.06901014"
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+       inkscape:export-ydpi="2.6500001" />
+    <text
+       id="text3778"
+       y="474.73837"
+       x="194.57605"
+       style="font-style:normal;font-weight:normal;font-size:10.58333302px;line-height:1.25;font-family:sans-serif;letter-spacing:0px;word-spacing:0px;fill:#000000;fill-opacity:1;stroke:none;stroke-width:0.26458332"
+       xml:space="preserve"
+       inkscape:export-xdpi="2.6500001"
+       inkscape:export-ydpi="2.6500001"><tspan
+         style="font-size:141.1111145px;fill:#ffffff;stroke-width:0.26458332"
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+         id="tspan3776"
+         sodipodi:role="line">net</tspan></text>
+    <rect
+       ry="50"
+       rx="50"
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+       inkscape:connector-curvature="0"
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+         style="font-weight:bold;font-size:141.1111145px;fill:#ffffff;stroke-width:0.26458332"
+         y="329.30466"
+         x="-639.42944"
+         id="tspan4654"
+         sodipodi:role="line">MQTT</tspan></text>
+    <text
+       xml:space="preserve"
+       style="font-style:normal;font-weight:normal;font-size:10.58333302px;line-height:1.25;font-family:sans-serif;letter-spacing:0px;word-spacing:0px;fill:#000000;fill-opacity:1;stroke:none;stroke-width:0.26458332"
+       x="-550.90747"
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+         x="-550.90747"
+         y="482.23267"
+         style="font-weight:bold;font-size:141.1111145px;fill:#ffffff;stroke-width:0.26458332">net</tspan></text>
+  </g>
+</svg>
@@ -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
@@ -1,5 +1,5 @@
 <p align="center">
-<img src="https://github.com/chkr1011/MQTTnet/blob/master/Images/Logo_128x128.png?raw=true" width="128">
+<img src="https://github.com/chkr1011/MQTTnet/blob/master/Images/icon_det_256.png?raw=true" width="196">
 <br/>
 <br/>
 </p>
@@ -7,8 +7,8 @@
 [![NuGet Badge](https://buildstats.info/nuget/MQTTnet)](https://www.nuget.org/packages/MQTTnet)
 [![Build status](https://ci.appveyor.com/api/projects/status/ycit86voxfevm2aa/branch/master?svg=true)](https://ci.appveyor.com/project/chkr1011/mqttnet)
 [![BCH compliance](https://bettercodehub.com/edge/badge/chkr1011/MQTTnet?branch=master)](https://bettercodehub.com/)
-[![OpenCollective](https://opencollective.com/mqttnet/backers/badge.svg)](https://opencollective.com/mqttnet) 
-[![OpenCollective](https://opencollective.com/mqttnet/sponsors/badge.svg)](https://opencollective.com/mqttnet) [![Join the chat at https://gitter.im/MQTTnet/community](https://badges.gitter.im/MQTTnet/community.svg)](https://gitter.im/MQTTnet/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Join the chat at https://gitter.im/MQTTnet/community](https://badges.gitter.im/MQTTnet/community.svg)](https://gitter.im/MQTTnet/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://raw.githubusercontent.com/chkr1011/MQTTnet/master/LICENSE)

 # MQTTnet

@@ -92,8 +92,6 @@ Please find examples and the documentation at the Wiki of this repository (<http
 If you want to contribute to this project just create a pull request. But only pull requests which are matching the code style of this library will be accepted. Before creating a pull request please have a look at the library to get an overview of the required style.
 Also additions and updates in the Wiki are welcome.

-**This project, like all projects requires time and money.  If you feel compelled to support the development team, you can do so through Open Collective (https://opencollective.com/mqttnet)**.
-
 ## References

 This library is used in the following projects:
@@ -104,6 +102,8 @@ This library is used in the following projects:
 * MQTT Tester (MQTT client test app for [Android](https://play.google.com/store/apps/details?id=com.liveowl.mqtttester) and [iOS](https://itunes.apple.com/us/app/mqtt-tester/id1278621826?mt=8))
 * Wirehome.Core (Open Source Home Automation system for .NET Core, <https://github.com/chkr1011/Wirehome.Core>)

+Further projects using this project can be found under https://github.com/chkr1011/MQTTnet/network/dependents.
+
 If you use this library and want to see your project here please create a pull request.

 ## License
@@ -1,17 +1,16 @@
-using System;
-using System.Net;
-using MQTTnet.Adapter;
+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));

@@ -1,13 +1,13 @@
-using System;
+using Microsoft.AspNetCore.Connections;
+using Microsoft.AspNetCore.Http.Features;
+using MQTTnet.Exceptions;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.IO.Pipelines;
 using System.Net;
 using System.Net.Sockets;
 using System.Threading.Tasks;
-using Microsoft.AspNetCore.Connections;
-using Microsoft.AspNetCore.Http.Features;
-using MQTTnet.Exceptions;

 namespace MQTTnet.AspNetCore.Client.Tcp
 {
@@ -40,8 +40,11 @@ namespace MQTTnet.AspNetCore.Client.Tcp
            _sender = new SocketSender(_socket, PipeScheduler.ThreadPool);
            _receiver = new SocketReceiver(_socket, PipeScheduler.ThreadPool);
        }
-
-        public Task DisposeAsync()
+#if NETCOREAPP3_1
+        public override ValueTask DisposeAsync()
+#else
+        public new Task DisposeAsync()
+#endif
        {
            IsConnected = false;

@@ -50,8 +53,15 @@ namespace MQTTnet.AspNetCore.Client.Tcp

            _socket?.Dispose();

+#if NETCOREAPP3_1
+
+            return base.DisposeAsync();
+        }
+#else
+
            return Task.CompletedTask;
        }
+#endif

        public async Task StartAsync()
        {
@@ -1,14 +1,13 @@
 using System;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.DependencyInjection;
-using System.Linq;
 using MQTTnet.Server;
-using System.Collections.Generic;

 namespace MQTTnet.AspNetCore
 {
    public static class ApplicationBuilderExtensions
    {
+        [Obsolete("This class is obsolete and will be removed in a future version. The recommended alternative is to use MapMqtt inside Microsoft.AspNetCore.Builder.UseEndpoints(...).")]
        public static IApplicationBuilder UseMqttEndpoint(this IApplicationBuilder app, string path = "/mqtt")
        {
            app.UseWebSockets();
@@ -24,7 +23,7 @@ namespace MQTTnet.AspNetCore

                if (context.Request.Headers.TryGetValue("Sec-WebSocket-Protocol", out var requestedSubProtocolValues))
                {
-                    subProtocol = SelectSubProtocol(requestedSubProtocolValues);
+                    subProtocol = MqttSubProtocolSelector.SelectSubProtocol(requestedSubProtocolValues);
                }

                var adapter = app.ApplicationServices.GetRequiredService<MqttWebSocketServerAdapter>();
@@ -37,14 +36,6 @@ namespace MQTTnet.AspNetCore
            return app;
        }

-        public static string SelectSubProtocol(IList<string> requestedSubProtocolValues)
-        {
-            // Order the protocols to also match "mqtt", "mqttv-3.1", "mqttv-3.11" etc.
-            return requestedSubProtocolValues
-                .OrderByDescending(p => p.Length)
-                .FirstOrDefault(p => p.ToLower().StartsWith("mqtt"));
-        }
-
        public static IApplicationBuilder UseMqttServer(this IApplicationBuilder app, Action<IMqttServer> configure)
        {
            var server = app.ApplicationServices.GetRequiredService<IMqttServer>();
@@ -0,0 +1,20 @@
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.Connections;
+using System;
+
+namespace MQTTnet.AspNetCore
+{
+    public static class ConnectionRouteBuilderExtensions
+    {
+#if NETCOREAPP3_1
+        [Obsolete("This class is obsolete and will be removed in a future version. The recommended alternative is to use MapMqtt inside Microsoft.AspNetCore.Builder.UseEndpoints(...).")]
+#endif
+        public static void MapMqtt(this ConnectionsRouteBuilder connection, PathString path)
+        {
+            connection.MapConnectionHandler<MqttConnectionHandler>(path, options =>
+            {
+                options.WebSockets.SubProtocolSelector = MqttSubProtocolSelector.SelectSubProtocol;
+            });
+        }
+    }
+}
@@ -0,0 +1,21 @@
+
+#if NETCOREAPP3_1
+
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Routing;
+
+namespace MQTTnet.AspNetCore
+{
+    public static class EndpointRouterExtensions
+    {
+        public static void MapMqtt(this IEndpointRouteBuilder endpoints, string pattern) 
+        {
+            endpoints.MapConnectionHandler<MqttConnectionHandler>(pattern, options =>
+            {
+                options.WebSockets.SubProtocolSelector = MqttSubProtocolSelector.SelectSubProtocol;
+            });
+        }
+    }
+}
+
+#endif
@@ -80,7 +80,7 @@ namespace MQTTnet.AspNetCore
            headerLength = 0;
            bodyLength = 0;
            
-            var temp = input.Slice(0, Math.Min(5, input.Length)).GetMemory();
+            var temp = input.Slice(0, Math.Min(5, input.Length)).GetMemory().Span;

            do
            {
@@ -88,7 +88,7 @@ namespace MQTTnet.AspNetCore
                {
                    return false;
                }
-                encodedByte = temp.Span[index];
+                encodedByte = temp[index];
                index++;

                value += (byte)(encodedByte & 127) * multiplier;
@@ -1,10 +1,10 @@
-using System;
-using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
-using MQTTnet.Server;
 using MQTTnet.Implementations;
+using MQTTnet.Server;
+using System;

 namespace MQTTnet.AspNetCore
 {
@@ -13,7 +13,7 @@ namespace MQTTnet.AspNetCore
        public static IServiceCollection AddHostedMqttServer(this IServiceCollection services, IMqttServerOptions options)
        {
            if (options == null) throw new ArgumentNullException(nameof(options));
-            
+
            services.AddSingleton(options);

            services.AddHostedMqttServer();
@@ -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();
@@ -60,14 +62,12 @@ 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>());
-            
+
            return services;
        }

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;netcoreapp2.1</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netcoreapp2.1;netcoreapp3.1</TargetFrameworks>
    <Product />
    <Company />
    <Authors />
@@ -14,11 +14,17 @@
    <DefineConstants>RELEASE;NETSTANDARD2_0</DefineConstants>
  </PropertyGroup>

-  <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.Connections.Abstractions" Version="2.1.3" />
-    <PackageReference Include="Microsoft.AspNetCore.Http.Connections" Version="1.0.3" />
-    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.1.1" />
-    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="2.1.1" />
+  <ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp3.1'">
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
+
+    <PackageReference Include="System.IO.Pipelines" Version="4.7.1" />
+  </ItemGroup>
+    
+  <ItemGroup Condition="'$(TargetFramework)' != 'netcoreapp3.1'">
+    <PackageReference Include="Microsoft.AspNetCore.Connections.Abstractions" Version="3.1.3" />
+    <PackageReference Include="Microsoft.AspNetCore.Http.Connections" Version="1.1.0" />
+    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.2.1" />
+    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="3.1.3" />
  </ItemGroup>

  <ItemGroup>
@@ -162,11 +162,12 @@ namespace MQTTnet.AspNetCore
                var buffer = formatter.Encode(packet);
                var msg = buffer.AsMemory();
                var output = _output;
-                msg.CopyTo(output.GetMemory(msg.Length));
-                BytesSent += msg.Length;
+                var result = await output.WriteAsync(msg, cancellationToken).ConfigureAwait(false);
+                if (result.IsCompleted)
+                {
+                    BytesSent += msg.Length;
+                }
                PacketFormatterAdapter.FreeBuffer();
-                output.Advance(msg.Length);
-                await output.FlushAsync().ConfigureAwait(false);
            }
            finally
            {
@@ -21,7 +21,8 @@ namespace MQTTnet.AspNetCore

        public Task StartAsync(CancellationToken cancellationToken)
        {
-            return StartAsync(_options);
+            _ = StartAsync(_options);
+            return Task.CompletedTask;
        }

        public Task StopAsync(CancellationToken cancellationToken)
@@ -0,0 +1,16 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace MQTTnet.AspNetCore
+{
+    public static class MqttSubProtocolSelector
+    {
+        public static string SelectSubProtocol(IList<string> requestedSubProtocolValues)
+        {
+            // Order the protocols to also match "mqtt", "mqttv-3.1", "mqttv-3.11" etc.
+            return requestedSubProtocolValues
+                .OrderByDescending(p => p.Length)
+                .FirstOrDefault(p => p.ToLower().StartsWith("mqtt"));
+        }
+    }
+}
@@ -1,20 +1,20 @@
-using System;
-using System.Net.WebSockets;
-using System.Threading.Tasks;
-using Microsoft.AspNetCore.Http;
+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));

@@ -38,7 +38,7 @@ namespace MQTTnet.AspNetCore
            if (webSocket == null) throw new ArgumentNullException(nameof(webSocket));

            var endpoint = $"{httpContext.Connection.RemoteIpAddress}:{httpContext.Connection.RemotePort}";
-            
+
            var clientCertificate = await httpContext.Connection.GetClientCertificateAsync().ConfigureAwait(false);
            try
            {
@@ -64,7 +64,6 @@ namespace MQTTnet.AspNetCore

            GrowIfNeeded(propertyWriter.Length);
            Write(propertyWriter.GetBuffer(), 0, propertyWriter.Length);
-            Commit(propertyWriter.Length);
        }

        public void Write(byte[] payload, int start, int length)
@@ -1,9 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Client;
+using MQTTnet.Client;
 using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
 using MQTTnet.Client.Publishing;
@@ -13,17 +8,34 @@ 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
 {
-    public class ManagedMqttClient : IManagedMqttClient
+    public class ManagedMqttClient : Disposable, IManagedMqttClient
    {
        private readonly BlockingQueue<ManagedMqttApplicationMessage> _messageQueue = new BlockingQueue<ManagedMqttApplicationMessage>();
+
+        /// <summary>
+        /// The subscriptions are managed in 2 separate buckets:
+        /// <see cref="_subscriptions"/> and <see cref="_unsubscriptions"/> are processed during normal operation
+        /// and are moved to the <see cref="_reconnectSubscriptions"/> when they get processed. They can be accessed by
+        /// any thread and are therefore mutex'ed. <see cref="_reconnectSubscriptions"/> get sent to the broker
+        ///  at reconnect and are solely owned by <see cref="MaintainConnectionAsync"/>.
+        /// </summary>
+        private readonly Dictionary<string, MqttQualityOfServiceLevel> _reconnectSubscriptions = new Dictionary<string, MqttQualityOfServiceLevel>();
        private readonly Dictionary<string, MqttQualityOfServiceLevel> _subscriptions = new Dictionary<string, MqttQualityOfServiceLevel>();
        private readonly HashSet<string> _unsubscriptions = new HashSet<string>();
+        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();

        private CancellationTokenSource _connectionCancellationToken;
        private CancellationTokenSource _publishingCancellationToken;
@@ -31,10 +43,7 @@ namespace MQTTnet.Extensions.ManagedClient

        private ManagedMqttClientStorageManager _storageManager;

-        private bool _disposed;
-        private bool _subscriptionsNotPushed;
-
-        public ManagedMqttClient(IMqttClient mqttClient, IMqttNetChildLogger logger)
+        public ManagedMqttClient(IMqttClient mqttClient, IMqttNetLogger logger)
        {
            _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));

@@ -80,10 +89,6 @@ namespace MQTTnet.Extensions.ManagedClient
            if (options == null) throw new ArgumentNullException(nameof(options));
            if (options.ClientOptions == null) throw new ArgumentException("The client options are not set.", nameof(options));

-            if (!options.ClientOptions.CleanSession)
-            {
-                throw new NotSupportedException("The managed client does not support existing sessions.");
-            }

            if (!_maintainConnectionTask?.IsCompleted ?? false) throw new InvalidOperationException("The managed client is already started.");

@@ -139,6 +144,7 @@ namespace MQTTnet.Extensions.ManagedClient
            ThrowIfDisposed();

            if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
+            if (Options == null) throw new InvalidOperationException("call StartAsync before publishing messages");

            MqttTopicValidator.ThrowIfInvalid(applicationMessage.ApplicationMessage.Topic);

@@ -147,7 +153,7 @@ namespace MQTTnet.Extensions.ManagedClient

            try
            {
-                lock (_messageQueue)
+                using (await _messageQueueLock.WaitAsync(CancellationToken.None).ConfigureAwait(false))
                {
                    if (_messageQueue.Count >= Options.MaxPendingMessages)
                    {
@@ -167,6 +173,16 @@ namespace MQTTnet.Extensions.ManagedClient
                    }

                    _messageQueue.Enqueue(applicationMessage);
+
+                    if (_storageManager != null)
+                    {
+                        if (removedMessage != null)
+                        {
+                            await _storageManager.RemoveAsync(removedMessage).ConfigureAwait(false);
+                        }
+
+                        await _storageManager.AddAsync(applicationMessage).ConfigureAwait(false);
+                    }
                }
            }
            finally
@@ -181,16 +197,6 @@ namespace MQTTnet.Extensions.ManagedClient
                }

            }
-            
-            if (_storageManager != null)
-            {
-                if (removedMessage != null)
-                {
-                    await _storageManager.RemoveAsync(removedMessage).ConfigureAwait(false);
-                }
-
-                await _storageManager.AddAsync(applicationMessage).ConfigureAwait(false);
-            }
        }

        public Task SubscribeAsync(IEnumerable<TopicFilter> topicFilters)
@@ -204,9 +210,10 @@ namespace MQTTnet.Extensions.ManagedClient
                foreach (var topicFilter in topicFilters)
                {
                    _subscriptions[topicFilter.Topic] = topicFilter.QualityOfServiceLevel;
-                    _subscriptionsNotPushed = true;
+                    _unsubscriptions.Remove(topicFilter.Topic);
                }
            }
+            _subscriptionsQueuedSignal.Release();

            return Task.FromResult(0);
        }
@@ -221,44 +228,34 @@ namespace MQTTnet.Extensions.ManagedClient
            {
                foreach (var topic in topics)
                {
-                    if (_subscriptions.Remove(topic))
-                    {
-                        _unsubscriptions.Add(topic);
-                        _subscriptionsNotPushed = true;
-                    }
+                    _subscriptions.Remove(topic);
+                    _unsubscriptions.Add(topic);
                }
            }
+            _subscriptionsQueuedSignal.Release();

            return Task.FromResult(0);
        }

-        public void Dispose()
+        protected override void Dispose(bool disposing)
        {
-            if (_disposed)
+            if (disposing)
            {
-                return;
-            }
-
-            _disposed = true;
-
-            StopPublishing();
-            StopMaintainingConnection();
-
-            if (_maintainConnectionTask != null)
-            {
-                Task.WaitAny(_maintainConnectionTask);
-                _maintainConnectionTask = null;
-            }
-
-            _mqttClient.Dispose();
-        }
-
-        private void ThrowIfDisposed()
-        {
-            if (_disposed)
-            {
-                throw new ObjectDisposedException(nameof(ManagedMqttClient));
+                StopPublishing();
+                StopMaintainingConnection();
+
+                if (_maintainConnectionTask != null)
+                {
+                    _maintainConnectionTask.GetAwaiter().GetResult();
+                    _maintainConnectionTask = null;
+                }
+
+                _messageQueue.Dispose();
+                _messageQueueLock.Dispose();
+                _mqttClient.Dispose();
+                _subscriptionsQueuedSignal.Dispose();
            }
+            base.Dispose(disposing);
        }

        private async Task MaintainConnectionAsync(CancellationToken cancellationToken)
@@ -275,11 +272,11 @@ namespace MQTTnet.Extensions.ManagedClient
            }
            catch (Exception exception)
            {
-                _logger.Error(exception, "Unhandled exception while maintaining connection.");
+                _logger.Error(exception, "Error exception while maintaining connection.");
            }
            finally
            {
-                if (!_disposed)
+                if (!IsDisposed)
                {
                    try
                    {
@@ -292,6 +289,12 @@ namespace MQTTnet.Extensions.ManagedClient

                    _logger.Info("Stopped");
                }
+                _reconnectSubscriptions.Clear();
+                lock (_subscriptions)
+                {
+                    _subscriptions.Clear();
+                    _unsubscriptions.Clear();
+                }
            }
        }

@@ -307,16 +310,22 @@ namespace MQTTnet.Extensions.ManagedClient
                    return;
                }

-                if (connectionState == ReconnectionResult.Reconnected || _subscriptionsNotPushed)
+                if (connectionState == ReconnectionResult.Reconnected)
+                {
+                    await PublishReconnectSubscriptionsAsync().ConfigureAwait(false);
+                    StartPublishing();
+                    return;
+                }
+
+                if (connectionState == ReconnectionResult.Recovered)
                {
-                    await SynchronizeSubscriptionsAsync().ConfigureAwait(false);
                    StartPublishing();
                    return;
                }

                if (connectionState == ReconnectionResult.StillConnected)
                {
-                    await Task.Delay(Options.ConnectionCheckInterval, cancellationToken).ConfigureAwait(false);
+                    await PublishSubscriptionsAsync(Options.ConnectionCheckInterval, cancellationToken).ConfigureAwait(false);
                }
            }
            catch (OperationCanceledException)
@@ -324,11 +333,11 @@ namespace MQTTnet.Extensions.ManagedClient
            }
            catch (MqttCommunicationException exception)
            {
-                _logger.Warning(exception, "Communication exception while maintaining connection.");
+                _logger.Warning(exception, "Communication error while maintaining connection.");
            }
            catch (Exception exception)
            {
-                _logger.Error(exception, "Unhandled exception while maintaining connection.");
+                _logger.Error(exception, "Error exception while maintaining connection.");
            }
        }

@@ -346,7 +355,7 @@ namespace MQTTnet.Extensions.ManagedClient
                    // of the messages, the DropOldestQueuedMessage strategy would
                    // be unable to know which message is actually the oldest and would
                    // instead drop the first item in the queue.
-                    var message = _messageQueue.PeekAndWait();
+                    var message = _messageQueue.PeekAndWait(cancellationToken);
                    if (message == null)
                    {
                        continue;
@@ -362,7 +371,7 @@ namespace MQTTnet.Extensions.ManagedClient
            }
            catch (Exception exception)
            {
-                _logger.Error(exception, "Unhandled exception while publishing queued application messages.");
+                _logger.Error(exception, "Error while publishing queued application messages.");
            }
            finally
            {
@@ -377,7 +386,7 @@ namespace MQTTnet.Extensions.ManagedClient
            {
                await _mqttClient.PublishAsync(message.ApplicationMessage).ConfigureAwait(false);

-                lock (_messageQueue) //lock to avoid conflict with this.PublishAsync
+                using (await _messageQueueLock.WaitAsync(CancellationToken.None).ConfigureAwait(false)) //lock to avoid conflict with this.PublishAsync
                {
                    // While publishing this message, this.PublishAsync could have booted this
                    // message off the queue to make room for another (when using a cap
@@ -386,11 +395,11 @@ namespace MQTTnet.Extensions.ManagedClient
                    // it from the queue.  If not, that means this.PublishAsync has already
                    // removed it, in which case we don't want to do anything.
                    _messageQueue.RemoveFirst(i => i.Id.Equals(message.Id));
-                }

-                if (_storageManager != null)
-                {
-                    await _storageManager.RemoveAsync(message).ConfigureAwait(false);
+                    if (_storageManager != null)
+                    {
+                        await _storageManager.RemoveAsync(message).ConfigureAwait(false);
+                    }
                }
            }
            catch (MqttCommunicationException exception)
@@ -408,21 +417,21 @@ namespace MQTTnet.Extensions.ManagedClient
                    //contradict the expected behavior of QoS 1 and 2, that's also true
                    //for the usage of a message queue cap, so it's still consistent
                    //with prior behavior in that way.
-                    lock (_messageQueue) //lock to avoid conflict with this.PublishAsync
+                    using (await _messageQueueLock.WaitAsync(CancellationToken.None).ConfigureAwait(false)) //lock to avoid conflict with this.PublishAsync
                    {
                        _messageQueue.RemoveFirst(i => i.Id.Equals(message.Id));
-                    }

-                    if (_storageManager != null)
-                    {
-                        await _storageManager.RemoveAsync(message).ConfigureAwait(false);
+                        if (_storageManager != null)
+                        {
+                            await _storageManager.RemoveAsync(message).ConfigureAwait(false);
+                        }
                    }
                }
            }
            catch (Exception exception)
            {
                transmitException = exception;
-                _logger.Error(exception, $"Unhandled exception while publishing application message ({message.Id}).");
+                _logger.Error(exception, $"Error while publishing application message ({message.Id}).");
            }
            finally
            {
@@ -435,50 +444,84 @@ namespace MQTTnet.Extensions.ManagedClient
            }
        }

-        private async Task SynchronizeSubscriptionsAsync()
+        private async Task PublishSubscriptionsAsync(TimeSpan timeout, CancellationToken cancellationToken)
        {
-            _logger.Info("Synchronizing subscriptions");
-
-            List<TopicFilter> subscriptions;
-            HashSet<string> unsubscriptions;
-
-            lock (_subscriptions)
+            var endTime = DateTime.UtcNow + timeout;
+            while (await _subscriptionsQueuedSignal.WaitAsync(GetRemainingTime(endTime), cancellationToken).ConfigureAwait(false))
            {
-                subscriptions = _subscriptions.Select(i => new TopicFilter { Topic = i.Key, QualityOfServiceLevel = i.Value }).ToList();
+                List<TopicFilter> subscriptions;
+                HashSet<string> unsubscriptions;

-                unsubscriptions = new HashSet<string>(_unsubscriptions);
-                _unsubscriptions.Clear();
+                lock (_subscriptions)
+                {
+                    subscriptions = _subscriptions.Select(i => new TopicFilter { Topic = i.Key, QualityOfServiceLevel = i.Value }).ToList();
+                    _subscriptions.Clear();
+                    unsubscriptions = new HashSet<string>(_unsubscriptions);
+                    _unsubscriptions.Clear();
+                }

-                _subscriptionsNotPushed = false;
+                if (!subscriptions.Any() && !unsubscriptions.Any())
+                {
+                    continue;
+                }
+
+                _logger.Verbose($"Publishing subscriptions ({subscriptions.Count} subscriptions and {unsubscriptions.Count} unsubscriptions)");
+
+                foreach (var unsubscription in unsubscriptions)
+                {
+                    _reconnectSubscriptions.Remove(unsubscription);
+                }
+
+                foreach (var subscription in subscriptions)
+                {
+                    _reconnectSubscriptions[subscription.Topic] = subscription.QualityOfServiceLevel;
+                }
+
+                try
+                {
+                    if (unsubscriptions.Any())
+                    {
+                        await _mqttClient.UnsubscribeAsync(unsubscriptions.ToArray()).ConfigureAwait(false);
+                    }
+
+                    if (subscriptions.Any())
+                    {
+                        await _mqttClient.SubscribeAsync(subscriptions.ToArray()).ConfigureAwait(false);
+                    }
+                }
+                catch (Exception exception)
+                {
+                    await HandleSubscriptionExceptionAsync(exception).ConfigureAwait(false);
+                }
            }
+        }

-            if (!subscriptions.Any() && !unsubscriptions.Any())
-            {
-                return;
-            }
+        private async Task PublishReconnectSubscriptionsAsync()
+        {
+            _logger.Info("Publishing subscriptions at reconnect");

            try
            {
-                if (unsubscriptions.Any())
-                {
-                    await _mqttClient.UnsubscribeAsync(unsubscriptions.ToArray()).ConfigureAwait(false);
-                }
-
-                if (subscriptions.Any())
+                if (_reconnectSubscriptions.Any())
                {
+                    var subscriptions = _reconnectSubscriptions.Select(i => new TopicFilter { Topic = i.Key, QualityOfServiceLevel = i.Value });
                    await _mqttClient.SubscribeAsync(subscriptions.ToArray()).ConfigureAwait(false);
                }
            }
            catch (Exception exception)
            {
-                _logger.Warning(exception, "Synchronizing subscriptions failed.");
-                _subscriptionsNotPushed = true;
+                await HandleSubscriptionExceptionAsync(exception).ConfigureAwait(false);
+            }
+        }

-                var synchronizingSubscriptionsFailedHandler = SynchronizingSubscriptionsFailedHandler;
-                if (SynchronizingSubscriptionsFailedHandler != null)
-                {
-                    await synchronizingSubscriptionsFailedHandler.HandleSynchronizingSubscriptionsFailedAsync(new ManagedProcessFailedEventArgs(exception)).ConfigureAwait(false);
-                }
+        private async Task HandleSubscriptionExceptionAsync(Exception exception)
+        {
+            _logger.Warning(exception, "Synchronizing subscriptions failed.");
+
+            var synchronizingSubscriptionsFailedHandler = SynchronizingSubscriptionsFailedHandler;
+            if (SynchronizingSubscriptionsFailedHandler != null)
+            {
+                await synchronizingSubscriptionsFailedHandler.HandleSynchronizingSubscriptionsFailedAsync(new ManagedProcessFailedEventArgs(exception)).ConfigureAwait(false);
            }
        }

@@ -491,8 +534,8 @@ namespace MQTTnet.Extensions.ManagedClient

            try
            {
-                await _mqttClient.ConnectAsync(Options.ClientOptions).ConfigureAwait(false);
-                return ReconnectionResult.Reconnected;
+                var result = await _mqttClient.ConnectAsync(Options.ClientOptions).ConfigureAwait(false);
+                return result.IsSessionPresent ? ReconnectionResult.Recovered : ReconnectionResult.Reconnected;
            }
            catch (Exception exception)
            {
@@ -505,7 +548,7 @@ namespace MQTTnet.Extensions.ManagedClient
                return ReconnectionResult.NotConnected;
            }
        }
-        
+
        private void StartPublishing()
        {
            if (_publishingCancellationToken != null)
@@ -532,5 +575,11 @@ namespace MQTTnet.Extensions.ManagedClient
            _connectionCancellationToken?.Dispose();
            _connectionCancellationToken = null;
        }
+
+        private TimeSpan GetRemainingTime(DateTime endTime)
+        {
+            var remainingTime = endTime - DateTime.UtcNow;
+            return remainingTime < TimeSpan.Zero ? TimeSpan.Zero : remainingTime;
+        }
    }
-}
+}
@@ -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);
        }
    }
 }
@@ -4,6 +4,7 @@
    {
        StillConnected,
        Reconnected,
+        Recovered,
        NotConnected
    }
 }
@@ -1,23 +1,32 @@
-using System;
+using MQTTnet.Client;
+using MQTTnet.Exceptions;
+using MQTTnet.Extensions.Rpc.Options;
+using MQTTnet.Extensions.Rpc.Options.TopicGeneration;
+using MQTTnet.Protocol;
+using System;
 using System.Collections.Concurrent;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Client;
-using MQTTnet.Exceptions;
-using MQTTnet.Protocol;

 namespace MQTTnet.Extensions.Rpc
 {
-    public class MqttRpcClient : IDisposable
+    public sealed class MqttRpcClient : IDisposable
    {
        private readonly ConcurrentDictionary<string, TaskCompletionSource<byte[]>> _waitingCalls = new ConcurrentDictionary<string, TaskCompletionSource<byte[]>>();
        private readonly IMqttClient _mqttClient;
+        private readonly IMqttRpcClientOptions _options;
        private readonly RpcAwareApplicationMessageReceivedHandler _applicationMessageReceivedHandler;

-        public MqttRpcClient(IMqttClient mqttClient)
+        [Obsolete("Use MqttRpcClient(IMqttClient mqttClient, IMqttRpcClientOptions options).")]
+        public MqttRpcClient(IMqttClient mqttClient) : this(mqttClient, new MqttRpcClientOptions())
+        {
+        }
+
+        public MqttRpcClient(IMqttClient mqttClient, IMqttRpcClientOptions options)
        {
            _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
+            _options = options ?? throw new ArgumentNullException(nameof(options));

            _applicationMessageReceivedHandler = new RpcAwareApplicationMessageReceivedHandler(
                mqttClient.ApplicationMessageReceivedHandler,
@@ -55,8 +64,26 @@ namespace MQTTnet.Extensions.Rpc
                throw new InvalidOperationException("The application message received handler was modified.");
            }

-            var requestTopic = $"MQTTnet.RPC/{Guid.NewGuid():N}/{methodName}";
-            var responseTopic = requestTopic + "/response";
+            var topicNames = _options.TopicGenerationStrategy.CreateRpcTopics(new TopicGenerationContext
+            {
+                MethodName = methodName,
+                QualityOfServiceLevel = qualityOfServiceLevel,
+                MqttClient = _mqttClient,
+                Options = _options
+            });
+
+            var requestTopic = topicNames.RequestTopic;
+            var responseTopic = topicNames.ResponseTopic;
+
+            if (string.IsNullOrWhiteSpace(requestTopic))
+            {
+                throw new MqttProtocolViolationException("RPC request topic is empty.");
+            }
+
+            if (string.IsNullOrWhiteSpace(responseTopic))
+            {
+                throw new MqttProtocolViolationException("RPC response topic is empty.");
+            }

            var requestMessage = new MqttApplicationMessageBuilder()
                .WithTopic(requestTopic)
@@ -74,7 +101,7 @@ namespace MQTTnet.Extensions.Rpc

                await _mqttClient.SubscribeAsync(responseTopic, qualityOfServiceLevel).ConfigureAwait(false);
                await _mqttClient.PublishAsync(requestMessage).ConfigureAwait(false);
-                
+
                using (var timeoutCts = new CancellationTokenSource(timeout))
                using (var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, timeoutCts.Token))
                {
@@ -0,0 +1,9 @@
+using MQTTnet.Extensions.Rpc.Options.TopicGeneration;
+
+namespace MQTTnet.Extensions.Rpc.Options
+{
+    public interface IMqttRpcClientOptions
+    {
+        IMqttRpcClientTopicGenerationStrategy TopicGenerationStrategy { get; set; }
+    }
+}
@@ -0,0 +1,9 @@
+using MQTTnet.Extensions.Rpc.Options.TopicGeneration;
+
+namespace MQTTnet.Extensions.Rpc.Options
+{
+    public class MqttRpcClientOptions : IMqttRpcClientOptions
+    {
+        public IMqttRpcClientTopicGenerationStrategy TopicGenerationStrategy { get; set; } = new DefaultMqttRpcClientTopicGenerationStrategy();
+    }
+}
@@ -0,0 +1,25 @@
+using MQTTnet.Extensions.Rpc.Options.TopicGeneration;
+using System;
+
+namespace MQTTnet.Extensions.Rpc.Options
+{
+    public class MqttRpcClientOptionsBuilder
+    {
+        IMqttRpcClientTopicGenerationStrategy _topicGenerationStrategy = new DefaultMqttRpcClientTopicGenerationStrategy();
+
+        public MqttRpcClientOptionsBuilder WithTopicGenerationStrategy(IMqttRpcClientTopicGenerationStrategy value)
+        {
+            _topicGenerationStrategy = value ?? throw new ArgumentNullException(nameof(value));
+
+            return this;
+        }
+
+        public IMqttRpcClientOptions Build()
+        {
+            return new MqttRpcClientOptions
+            {
+                TopicGenerationStrategy = _topicGenerationStrategy
+            };
+        }
+    }
+}
@@ -0,0 +1,9 @@
+namespace MQTTnet.Extensions.Rpc.Options
+{
+    public class MqttRpcTopicPair
+    {
+        public string RequestTopic { get; set; }
+
+        public string ResponseTopic { get; set; }
+    }
+}
@@ -0,0 +1,20 @@
+using MQTTnet.Extensions.Rpc.Options.TopicGeneration;
+using System;
+
+namespace MQTTnet.Extensions.Rpc.Options
+{
+    public class DefaultMqttRpcClientTopicGenerationStrategy : IMqttRpcClientTopicGenerationStrategy
+    {
+        public MqttRpcTopicPair CreateRpcTopics(TopicGenerationContext context)
+        {
+            var requestTopic = $"MQTTnet.RPC/{Guid.NewGuid():N}/{context.MethodName}";
+            var responseTopic = requestTopic + "/response";
+
+            return new MqttRpcTopicPair
+            {
+                RequestTopic = requestTopic,
+                ResponseTopic = responseTopic
+            };
+        }
+    }
+}
@@ -0,0 +1,7 @@
+namespace MQTTnet.Extensions.Rpc.Options.TopicGeneration
+{
+    public interface IMqttRpcClientTopicGenerationStrategy
+    {
+        MqttRpcTopicPair CreateRpcTopics(TopicGenerationContext context);
+    }
+}
@@ -0,0 +1,16 @@
+using MQTTnet.Client;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Extensions.Rpc.Options.TopicGeneration
+{
+    public class TopicGenerationContext
+    {
+        public string MethodName { get; set; }
+
+        public MqttQualityOfServiceLevel QualityOfServiceLevel { get; set; }
+
+        public IMqttClient MqttClient { get; set; }
+
+        public IMqttRpcClientOptions Options { get; set; }
+    }
+}
@@ -85,7 +85,12 @@ namespace MQTTnet.Extensions.WebSocket4Net
            {
                foreach (var certificate in _webSocketOptions.TlsOptions.Certificates)
                {
+#if WINDOWS_UWP
                    certificates.Add(new X509Certificate(certificate));
+#else
+                    certificates.Add(certificate);
+#endif
+                    
                }
            }

@@ -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();
+                    }
            }
        }
    }
@@ -0,0 +1,35 @@
+using System.IO;
+
+namespace MQTTnet.Server.Configuration
+{
+    public class CertificateSettingsModel
+    {
+        /// <summary>
+        /// Path to certificate.
+        /// </summary>
+        public string Path { get; set; }
+        
+        /// <summary>
+        /// Password of certificate.
+        /// </summary>
+        public string Password { get; set; }
+
+        /// <summary>
+        /// Read certificate file.
+        /// </summary>
+        public byte[] ReadCertificate()
+        {
+            if (string.IsNullOrEmpty(Path) || string.IsNullOrWhiteSpace(Path))
+            {
+                throw new FileNotFoundException("No path set");
+            }
+
+            if (!File.Exists(Path))
+            {
+                throw new FileNotFoundException($"Could not find Certificate in path: {Path}");
+            }
+
+            return File.ReadAllBytes(Path);
+        }
+    }
+}
@@ -9,9 +9,9 @@ namespace MQTTnet.Server.Configuration
    public class TcpEndPointModel
    {
        /// <summary>
-        /// Path to Certificate
+        /// Certificate settings.
        /// </summary>
-        public string CertificatePath { get; set; }
+        public CertificateSettingsModel Certificate { get; set; }

        /// <summary>
        /// Enabled / Disable
@@ -33,25 +33,6 @@ namespace MQTTnet.Server.Configuration
        /// </summary>
        public int Port { get; set; } = 1883;

-        /// <summary>
-        /// Read Certificate file
-        /// </summary>
-        /// <returns></returns>
-        public byte[] ReadCertificate()
-        {
-            if (string.IsNullOrEmpty(CertificatePath) || string.IsNullOrWhiteSpace(CertificatePath))
-            {
-                throw new FileNotFoundException("No path set");
-            }
-
-            if (!File.Exists(CertificatePath))
-            {
-                throw new FileNotFoundException($"Could not find Certificate in path: {CertificatePath}");
-            }
-
-            return File.ReadAllBytes(CertificatePath);
-        }
-
        /// <summary>
        /// Read IPv4
        /// </summary>
@@ -13,7 +13,7 @@ namespace MQTTnet.Server.Controllers
 {
    [Authorize]
    [ApiController]
-    public class ClientsController : ControllerBase
+    public class ClientsController : Controller
    {
        private readonly MqttServerService _mqttServerService;

@@ -0,0 +1,51 @@
+using System;
+using System.IO;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using MQTTnet.Protocol;
+using MQTTnet.Server.Mqtt;
+
+namespace MQTTnet.Server.Controllers
+{
+    [Authorize]
+    [ApiController]
+    public class MessagesController : Controller
+    {
+        private readonly MqttServerService _mqttServerService;
+
+        public MessagesController(MqttServerService mqttServerService)
+        {
+            _mqttServerService = mqttServerService ?? throw new ArgumentNullException(nameof(mqttServerService));
+        }
+
+        [Route("api/v1/messages")]
+        [HttpPost]
+        public async Task<ActionResult> PostMessage(MqttApplicationMessage message)
+        {
+            await _mqttServerService.PublishAsync(message);
+            return Ok();
+        }
+
+        [Route("api/v1/messages/{*topic}")]
+        [HttpPost]
+        public async Task<ActionResult> PostMessage(string topic, int qosLevel = 0)
+        {
+            byte[] payload;
+
+            using (var memoryStream = new MemoryStream())
+            {
+                await HttpContext.Request.Body.CopyToAsync(memoryStream);
+                payload = memoryStream.ToArray();
+            }
+
+            var message = new MqttApplicationMessageBuilder()
+                .WithTopic(topic)
+                .WithPayload(payload)
+                .WithQualityOfServiceLevel((MqttQualityOfServiceLevel)qosLevel)
+                .Build();
+
+            return await PostMessage(message);
+        }
+    }
+}
@@ -12,7 +12,7 @@ namespace MQTTnet.Server.Controllers
 {
    [Authorize]
    [ApiController]
-    public class RetainedApplicationMessagesController : ControllerBase
+    public class RetainedApplicationMessagesController : Controller
    {
        private readonly MqttServerService _mqttServerService;

@@ -0,0 +1,18 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using System.Reflection;
+
+namespace MQTTnet.Server.Controllers
+{
+    [Authorize]
+    [ApiController]
+    public class ServerController : Controller
+    {
+        [Route("api/v1/server/version")]
+        [HttpGet]
+        public ActionResult<string> GetVersion()
+        {
+            return Assembly.GetExecutingAssembly().GetCustomAttribute<AssemblyInformationalVersionAttribute>().InformationalVersion;
+        }
+    }
+}
@@ -13,7 +13,7 @@ namespace MQTTnet.Server.Controllers
 {
    [Authorize]
    [ApiController]
-    public class SessionsController : ControllerBase
+    public class SessionsController : Controller
    {
        private readonly MqttServerService _mqttServerService;

@@ -1,43 +1,43 @@
-using System;
-using MQTTnet.Diagnostics;
+//using MQTTnet.Diagnostics;
+//using System;

-namespace MQTTnet.Server.Logging
-{
-    public class MqttNetChildLoggerWrapper : IMqttNetChildLogger
-    {
-        private readonly MqttNetLoggerWrapper _logger;
-        private readonly string _source;
+//namespace MQTTnet.Server.Logging
+//{
+//    public class MqttNetChildLoggerWrapper : IMqttNetChildLogger
+//    {
+//        private readonly MqttNetLoggerWrapper _logger;
+//        private readonly string _source;

-        public MqttNetChildLoggerWrapper(string source, MqttNetLoggerWrapper logger)
-        {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+//        public MqttNetChildLoggerWrapper(string source, MqttNetLoggerWrapper logger)
+//        {
+//            _logger = logger ?? throw new ArgumentNullException(nameof(logger));

-            _source = source;
-        }
+//            _source = source;
+//        }

-        public IMqttNetChildLogger CreateChildLogger(string source = null)
-        {
-            return _logger.CreateChildLogger(source);
-        }
+//        public IMqttNetLogger CreateChildLogger(string source = null)
+//        {
+//            return _logger.CreateChildLogger(source);
+//        }

-        public void Verbose(string message, params object[] parameters)
-        {
-            _logger.Publish(MqttNetLogLevel.Verbose, _source, message, parameters, null);
-        }
+//        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 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 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);
-        }
-    }
-}
+//        public void Error(Exception exception, string message, params object[] parameters)
+//        {
+//            _logger.Publish(MqttNetLogLevel.Error, _source, message, parameters, exception);
+//        }
+//    }
+//}
@@ -1,13 +1,13 @@
-using System;
-using System.Threading;
-using Microsoft.Extensions.Logging;
+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)
            {
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
    <AssemblyName>MQTTnet.Server</AssemblyName>
    <RootNamespace>MQTTnet.Server</RootNamespace>
@@ -43,14 +43,12 @@
  </ItemGroup>

  <ItemGroup>
-    <PackageReference Include="IronPython" Version="2.7.9" />
-    <PackageReference Include="IronPython.StdLib" Version="2.7.9" />
-    <PackageReference Include="Microsoft.AspNetCore.App" />
-    <PackageReference Include="Microsoft.AspNetCore.Razor.Design" Version="2.2.0" PrivateAssets="All" />
-    <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="2.2.0" />
-    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.2.1" />
-    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerGen" Version="5.0.0-rc2" />
-    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="5.0.0-rc2" />
+    <PackageReference Include="IronPython" Version="2.7.10-candidate1" />
+    <PackageReference Include="IronPython.StdLib" Version="2.7.10-candidate1" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.1.3" />
+    <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>
@@ -22,14 +22,18 @@ namespace MQTTnet.Server.Mqtt
        {
            try
            {
+                // This might be not set when a message was published by the server instead of a client.
+                context.SessionItems.TryGetValue(MqttServerConnectionValidator.WrappedSessionItemsKey, out var sessionItems);
+
                var pythonContext = new PythonDictionary
                {
+                    { "client_id", context.ClientId },
+                    { "session_items", sessionItems },
+                    { "retain", context.ApplicationMessage.Retain },
                    { "accept_publish", context.AcceptPublish },
                    { "close_connection", context.CloseConnection },
-                    { "client_id", context.ClientId },
                    { "topic", context.ApplicationMessage.Topic },
-                    { "qos", (int)context.ApplicationMessage.QualityOfServiceLevel },
-                    { "retain", context.ApplicationMessage.Retain }
+                    { "qos", (int)context.ApplicationMessage.QualityOfServiceLevel }
                };
                
                _pythonScriptHostService.InvokeOptionalFunction("on_intercept_application_message", pythonContext);
@@ -47,4 +51,4 @@ namespace MQTTnet.Server.Mqtt
            return Task.CompletedTask;
        }
    }
-}
+}
@@ -9,6 +9,8 @@ namespace MQTTnet.Server.Mqtt
 {
    public class MqttServerConnectionValidator : IMqttServerConnectionValidator
    {
+        public const string WrappedSessionItemsKey = "WRAPPED_ITEMS";
+
        private readonly PythonScriptHostService _pythonScriptHostService;
        private readonly ILogger _logger;

@@ -22,6 +24,8 @@ namespace MQTTnet.Server.Mqtt
        {
            try
            {
+                var sessionItems = new PythonDictionary();
+
                var pythonContext = new PythonDictionary
                {
                    { "endpoint", context.Endpoint },
@@ -33,6 +37,7 @@ namespace MQTTnet.Server.Mqtt
                    { "clean_session", context.CleanSession},
                    { "authentication_method", context.AuthenticationMethod},
                    { "authentication_data", new Bytes(context.AuthenticationData ?? new byte[0]) },
+                    { "session_items", sessionItems },

                    { "result", PythonConvert.Pythonfy(context.ReasonCode) }
                };
@@ -40,6 +45,8 @@ namespace MQTTnet.Server.Mqtt
                _pythonScriptHostService.InvokeOptionalFunction("on_validate_client_connection", pythonContext);

                context.ReasonCode = PythonConvert.ParseEnum<MqttConnectReasonCode>((string)pythonContext["result"]);
+
+                context.SessionItems[WrappedSessionItemsKey] = sessionItems;
            }
            catch (Exception exception)
            {
@@ -1,11 +1,4 @@
-using System;
-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 IronPython.Runtime;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Logging;
 using MQTTnet.Adapter;
@@ -16,25 +9,33 @@ 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
 {
    public class MqttServerService
    {
-        private readonly ILogger<MqttServerService> _logger;
+        readonly ILogger<MqttServerService> _logger;

-        private readonly MqttSettingsModel _settings;
-        private readonly MqttApplicationMessageInterceptor _mqttApplicationMessageInterceptor;
-        private readonly MqttServerStorage _mqttServerStorage;
-        private readonly MqttClientConnectedHandler _mqttClientConnectedHandler;
-        private readonly MqttClientDisconnectedHandler _mqttClientDisconnectedHandler;
-        private readonly MqttClientSubscribedTopicHandler _mqttClientSubscribedTopicHandler;
-        private readonly MqttClientUnsubscribedTopicHandler _mqttClientUnsubscribedTopicHandler;
-        private readonly MqttServerConnectionValidator _mqttConnectionValidator;
-        private readonly IMqttServer _mqttServer;
-        private readonly MqttSubscriptionInterceptor _mqttSubscriptionInterceptor;
-        private readonly PythonScriptHostService _pythonScriptHostService;
-        private readonly MqttWebSocketServerAdapter _webSocketServerAdapter;
+        readonly MqttSettingsModel _settings;
+        readonly MqttApplicationMessageInterceptor _mqttApplicationMessageInterceptor;
+        readonly MqttServerStorage _mqttServerStorage;
+        readonly MqttClientConnectedHandler _mqttClientConnectedHandler;
+        readonly MqttClientDisconnectedHandler _mqttClientDisconnectedHandler;
+        readonly MqttClientSubscribedTopicHandler _mqttClientSubscribedTopicHandler;
+        readonly MqttClientUnsubscribedTopicHandler _mqttClientUnsubscribedTopicHandler;
+        readonly MqttServerConnectionValidator _mqttConnectionValidator;
+        readonly IMqttServer _mqttServer;
+        readonly MqttSubscriptionInterceptor _mqttSubscriptionInterceptor;
+        readonly MqttUnsubscriptionInterceptor _mqttUnsubscriptionInterceptor;
+        readonly PythonScriptHostService _pythonScriptHostService;
+        readonly MqttWebSocketServerAdapter _webSocketServerAdapter;

        public MqttServerService(
            MqttSettingsModel mqttSettings,
@@ -45,9 +46,10 @@ namespace MQTTnet.Server.Mqtt
            MqttClientUnsubscribedTopicHandler mqttClientUnsubscribedTopicHandler,
            MqttServerConnectionValidator mqttConnectionValidator,
            MqttSubscriptionInterceptor mqttSubscriptionInterceptor,
+            MqttUnsubscriptionInterceptor mqttUnsubscriptionInterceptor,
            MqttApplicationMessageInterceptor mqttApplicationMessageInterceptor,
            MqttServerStorage mqttServerStorage,
-            PythonScriptHostService pythonScriptHostService,            
+            PythonScriptHostService pythonScriptHostService,
            ILogger<MqttServerService> logger)
        {
            _settings = mqttSettings ?? throw new ArgumentNullException(nameof(mqttSettings));
@@ -57,16 +59,17 @@ namespace MQTTnet.Server.Mqtt
            _mqttClientUnsubscribedTopicHandler = mqttClientUnsubscribedTopicHandler ?? throw new ArgumentNullException(nameof(mqttClientUnsubscribedTopicHandler));
            _mqttConnectionValidator = mqttConnectionValidator ?? throw new ArgumentNullException(nameof(mqttConnectionValidator));
            _mqttSubscriptionInterceptor = mqttSubscriptionInterceptor ?? throw new ArgumentNullException(nameof(mqttSubscriptionInterceptor));
+            _mqttUnsubscriptionInterceptor = mqttUnsubscriptionInterceptor ?? throw new ArgumentNullException(nameof(mqttUnsubscriptionInterceptor));
            _mqttApplicationMessageInterceptor = mqttApplicationMessageInterceptor ?? throw new ArgumentNullException(nameof(mqttApplicationMessageInterceptor));
            _mqttServerStorage = mqttServerStorage ?? throw new ArgumentNullException(nameof(mqttServerStorage));
            _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.
                },
@@ -124,7 +127,7 @@ namespace MQTTnet.Server.Mqtt
            return _mqttServer.PublishAsync(applicationMessage);
        }

-        private void Publish(PythonDictionary parameters)
+        void Publish(PythonDictionary parameters)
        {
            try
            {
@@ -170,7 +173,7 @@ namespace MQTTnet.Server.Mqtt
            }
        }

-        private IMqttServerOptions CreateMqttServerOptions()
+        IMqttServerOptions CreateMqttServerOptions()
        {
            var options = new MqttServerOptionsBuilder()
                .WithMaxPendingMessagesPerClient(_settings.MaxPendingMessagesPerClient)
@@ -178,8 +181,9 @@ namespace MQTTnet.Server.Mqtt
                .WithConnectionValidator(_mqttConnectionValidator)
                .WithApplicationMessageInterceptor(_mqttApplicationMessageInterceptor)
                .WithSubscriptionInterceptor(_mqttSubscriptionInterceptor)
+                .WithUnsubscriptionInterceptor(_mqttUnsubscriptionInterceptor)
                .WithStorage(_mqttServerStorage);
-            
+
            // Configure unencrypted connections
            if (_settings.TcpEndPoint.Enabled)
            {
@@ -210,8 +214,22 @@ namespace MQTTnet.Server.Mqtt
            {
                options
                    .WithEncryptedEndpoint()
-                    .WithEncryptionSslProtocol(SslProtocols.Tls12)
-                    .WithEncryptionCertificate(_settings.EncryptedTcpEndPoint.ReadCertificate());
+                    .WithEncryptionSslProtocol(SslProtocols.Tls12);
+
+                if (!string.IsNullOrEmpty(_settings.EncryptedTcpEndPoint?.Certificate?.Path))
+                {
+                    IMqttServerCertificateCredentials certificateCredentials = null;
+
+                    if (!string.IsNullOrEmpty(_settings.EncryptedTcpEndPoint?.Certificate?.Password))
+                    {
+                        certificateCredentials = new MqttServerCertificateCredentials
+                        {
+                            Password = _settings.EncryptedTcpEndPoint.Certificate.Password
+                        };
+                    }
+
+                    options.WithEncryptionCertificate(_settings.EncryptedTcpEndPoint.Certificate.ReadCertificate(), certificateCredentials);
+                }

                if (_settings.EncryptedTcpEndPoint.TryReadIPv4(out var address4))
                {
@@ -21,14 +21,16 @@ namespace MQTTnet.Server.Mqtt
        {
            try
            {
+                var sessionItems = (PythonDictionary)context.SessionItems[MqttServerConnectionValidator.WrappedSessionItemsKey];
+
                var pythonContext = new PythonDictionary
                {
-                    { "accept_subscription", context.AcceptSubscription },
-                    { "close_connection", context.CloseConnection },
-
                    { "client_id", context.ClientId },
+                    { "session_items", sessionItems },
                    { "topic", context.TopicFilter.Topic },
-                    { "qos", (int)context.TopicFilter.QualityOfServiceLevel }
+                    { "qos", (int)context.TopicFilter.QualityOfServiceLevel },
+                    { "accept_subscription", context.AcceptSubscription },
+                    { "close_connection", context.CloseConnection }
                };

                _pythonScriptHostService.InvokeOptionalFunction("on_intercept_subscription", pythonContext);
@@ -0,0 +1,48 @@
+using System;
+using System.Threading.Tasks;
+using IronPython.Runtime;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Server.Scripting;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class MqttUnsubscriptionInterceptor : IMqttServerUnsubscriptionInterceptor
+    {
+        private readonly PythonScriptHostService _pythonScriptHostService;
+        private readonly ILogger _logger;
+
+        public MqttUnsubscriptionInterceptor(PythonScriptHostService pythonScriptHostService, ILogger<MqttUnsubscriptionInterceptor> logger)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public Task InterceptUnsubscriptionAsync(MqttUnsubscriptionInterceptorContext context)
+        {
+            try
+            {
+                var sessionItems = (PythonDictionary)context.SessionItems[MqttServerConnectionValidator.WrappedSessionItemsKey];
+
+                var pythonContext = new PythonDictionary
+                {
+                    { "client_id", context.ClientId },
+                    { "session_items", sessionItems },
+                    { "topic", context.Topic },
+                    { "accept_unsubscription", context.AcceptUnsubscription },
+                    { "close_connection", context.CloseConnection }
+                };
+
+                _pythonScriptHostService.InvokeOptionalFunction("on_intercept_unsubscription", pythonContext);
+
+                context.AcceptUnsubscription = (bool)pythonContext["accept_unsubscription"];
+                context.CloseConnection = (bool)pythonContext["close_connection"];
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Error while intercepting unsubscription.");
+            }
+
+            return Task.CompletedTask;
+        }
+    }
+}
@@ -1,8 +1,8 @@
-using System;
-using System.Reflection;
-using Microsoft.AspNetCore;
-using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.Hosting;
 using MQTTnet.Server.Web;
+using System;
+using System.Reflection;

 namespace MQTTnet.Server
 {
@@ -14,7 +14,15 @@ namespace MQTTnet.Server
            {
                PrintLogo();

-                WebHost.CreateDefaultBuilder(args).UseStartup<Startup>().Build().Run();
+                Host.CreateDefaultBuilder(args)
+                    .ConfigureWebHostDefaults(webBuilder =>
+                    {
+                        webBuilder.ConfigureKestrel(serverOptions =>
+                        {
+                        })
+                        .UseStartup<Startup>();
+
+                    }).Build().Run();

                return 0;
            }
@@ -25,7 +33,7 @@ namespace MQTTnet.Server
            }
        }

-        private static void PrintLogo()
+        static void PrintLogo()
        {
            Console.ResetColor();
            Console.ForegroundColor = ConsoleColor.Red;
@@ -46,9 +54,7 @@ namespace MQTTnet.Server
            Console.WriteLine();
            Console.ForegroundColor = ConsoleColor.White;
            Console.WriteLine("The official MQTT server implementation of MQTTnet");
-            Console.WriteLine("Copyright (c) 2017-2019 The MQTTnet Team");
-
-            Console.ForegroundColor = ConsoleColor.Blue;
+            Console.WriteLine("Copyright (c) 2017-2020 The MQTTnet Team");
            Console.WriteLine(@"https://github.com/chkr1011/MQTTnet");

            Console.ForegroundColor = ConsoleColor.White;
@@ -1,14 +1,14 @@
-using System;
+using Microsoft.Extensions.Logging;
+using System;
 using System.Collections.Generic;
-using Microsoft.Extensions.Logging;

 namespace MQTTnet.Server.Scripting.DataSharing
 {
    public class DataSharingService
    {
-        private readonly Dictionary<string, object> _storage = new Dictionary<string, object>();
-        private readonly PythonScriptHostService _pythonScriptHostService;
-        private readonly ILogger<DataSharingService> _logger;
+        readonly Dictionary<string, object> _storage = new Dictionary<string, object>();
+        readonly PythonScriptHostService _pythonScriptHostService;
+        readonly ILogger<DataSharingService> _logger;

        public DataSharingService(PythonScriptHostService pythonScriptHostService, ILogger<DataSharingService> logger)
        {
@@ -1,14 +1,14 @@
-using System;
+using Microsoft.Extensions.Logging;
+using System;
 using System.IO;
 using System.Text;
-using Microsoft.Extensions.Logging;

 namespace MQTTnet.Server.Scripting
 {
    public class PythonIOStream : Stream
    {
-        private readonly ILogger _logger;
-        private readonly Encoding _encoder = Encoding.UTF8;
+        readonly ILogger _logger;
+        readonly Encoding _encoder = Encoding.UTF8;

        public PythonIOStream(ILogger<PythonIOStream> logger)
        {
@@ -1,4 +1,8 @@
-using System;
+using Microsoft.Extensions.Logging;
+using Microsoft.Scripting;
+using Microsoft.Scripting.Hosting;
+using MQTTnet.Server.Configuration;
+using System;
 using System.Collections.Generic;
 using System.Dynamic;
 using System.IO;
@@ -6,22 +10,18 @@ using System.Linq;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.Extensions.Logging;
-using Microsoft.Scripting;
-using Microsoft.Scripting.Hosting;
-using MQTTnet.Server.Configuration;

 namespace MQTTnet.Server.Scripting
 {
    public class PythonScriptHostService
    {
-        private readonly IDictionary<string, object> _proxyObjects = new ExpandoObject();
-        private readonly List<PythonScriptInstance> _scriptInstances = new List<PythonScriptInstance>();
-        private readonly string _scriptsPath;
-        private readonly ScriptingSettingsModel _scriptingSettings;
-        private readonly ILogger<PythonScriptHostService> _logger;
-        private readonly ScriptEngine _scriptEngine;
-        
+        readonly IDictionary<string, object> _proxyObjects = new ExpandoObject();
+        readonly List<PythonScriptInstance> _scriptInstances = new List<PythonScriptInstance>();
+        readonly string _scriptsPath;
+        readonly ScriptingSettingsModel _scriptingSettings;
+        readonly ILogger<PythonScriptHostService> _logger;
+        readonly ScriptEngine _scriptEngine;
+
        public PythonScriptHostService(ScriptingSettingsModel scriptingSettings, PythonIOStream pythonIOStream, ILogger<PythonScriptHostService> logger)
        {
            _scriptingSettings = scriptingSettings ?? throw new ArgumentNullException(nameof(scriptingSettings));
@@ -139,7 +139,7 @@ namespace MQTTnet.Server.Scripting
            }
        }

-        private async Task TryInitializeScriptAsync(string path)
+        async Task TryInitializeScriptAsync(string path)
        {
            var uid = new FileInfo(path).Name.Replace(".py", string.Empty, StringComparison.OrdinalIgnoreCase);

@@ -155,7 +155,7 @@ namespace MQTTnet.Server.Scripting
                {
                    _scriptInstances.Add(scriptInstance);
                }
-                
+
                _logger.LogInformation($"Initialized script '{uid}'.");
            }
            catch (Exception exception)
@@ -164,7 +164,7 @@ namespace MQTTnet.Server.Scripting
            }
        }

-        private PythonScriptInstance CreateScriptInstance(string uid, string path, string code)
+        PythonScriptInstance CreateScriptInstance(string uid, string path, string code)
        {
            var scriptScope = _scriptEngine.CreateScope();

@@ -173,11 +173,11 @@ namespace MQTTnet.Server.Scripting

            scriptScope.SetVariable("mqtt_net_server", _proxyObjects);
            compiledCode.Execute(scriptScope);
-            
+
            return new PythonScriptInstance(uid, path, scriptScope);
        }

-        private void AddSearchPaths(ScriptEngine scriptEngine)
+        void AddSearchPaths(ScriptEngine scriptEngine)
        {
            if (_scriptingSettings.IncludePaths?.Any() != true)
            {
@@ -1,12 +1,12 @@
-using System;
-using IronPython.Runtime;
+using IronPython.Runtime;
 using Microsoft.Scripting.Hosting;
+using System;

 namespace MQTTnet.Server.Scripting
 {
    public class PythonScriptInstance
    {
-        private readonly ScriptScope _scriptScope;
+        readonly ScriptScope _scriptScope;

        public PythonScriptInstance(string uid, string path, ScriptScope scriptScope)
        {
@@ -1,10 +1,5 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Net;
-using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
@@ -16,7 +11,12 @@ using MQTTnet.Server.Logging;
 using MQTTnet.Server.Mqtt;
 using MQTTnet.Server.Scripting;
 using MQTTnet.Server.Scripting.DataSharing;
+using Newtonsoft.Json.Converters;
 using Swashbuckle.AspNetCore.SwaggerUI;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;

 namespace MQTTnet.Server.Web
 {
@@ -35,33 +35,27 @@ namespace MQTTnet.Server.Web

        public void Configure(
            IApplicationBuilder application,
-            IHostingEnvironment environment,
            MqttServerService mqttServerService,
            PythonScriptHostService pythonScriptHostService,
            DataSharingService dataSharingService,
            MqttSettingsModel mqttSettings)
        {
-            if (environment.IsDevelopment())
-            {
-                application.UseDeveloperExceptionPage();
-            }
-            else
-            {
-                application.UseHsts();
-            }
-
+            application.UseHsts();
+            application.UseRouting();
            application.UseCors(x => x
                .AllowAnyOrigin()
                .AllowAnyMethod()
-                .AllowAnyHeader()
-                .AllowCredentials());
+                .AllowAnyHeader());

            application.UseAuthentication();
+            application.UseAuthorization();

            application.UseStaticFiles();

-            application.UseHttpsRedirection();
-            application.UseMvc();
+            application.UseEndpoints(endpoints =>
+            {
+                endpoints.MapControllers();
+            });

            ConfigureWebSocketEndpoint(application, mqttServerService, mqttSettings);

@@ -87,11 +81,14 @@ namespace MQTTnet.Server.Web
        {
            services.AddCors();

+
+            services.AddControllers();
+
            services.AddMvc()
-                .SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
-                .AddJsonOptions(options =>
+                .SetCompatibilityVersion(CompatibilityVersion.Version_3_0)
+                .AddNewtonsoftJson(o =>
                {
-                    options.SerializerSettings.Converters.Add(new Newtonsoft.Json.Converters.StringEnumConverter());
+                    o.SerializerSettings.Converters.Add(new StringEnumConverter());
                });

            ReadMqttSettings(services);
@@ -111,12 +108,11 @@ namespace MQTTnet.Server.Web
            services.AddSingleton<MqttClientUnsubscribedTopicHandler>();
            services.AddSingleton<MqttServerConnectionValidator>();
            services.AddSingleton<MqttSubscriptionInterceptor>();
+            services.AddSingleton<MqttUnsubscriptionInterceptor>();
            services.AddSingleton<MqttApplicationMessageInterceptor>();

            services.AddSwaggerGen(c =>
            {
-                c.DescribeAllEnumsAsStrings();
-                
                var securityScheme = new OpenApiSecurityScheme
                {
                    Scheme = "Basic",
@@ -156,7 +152,7 @@ namespace MQTTnet.Server.Web
                .AddCookie();
        }

-        private void ReadMqttSettings(IServiceCollection services)
+        void ReadMqttSettings(IServiceCollection services)
        {
            var mqttSettings = new MqttSettingsModel();
            Configuration.Bind("MQTT", mqttSettings);
@@ -167,7 +163,7 @@ namespace MQTTnet.Server.Web
            services.AddSingleton(scriptingSettings);
        }

-        private static void ConfigureWebSocketEndpoint(
+        static void ConfigureWebSocketEndpoint(
            IApplicationBuilder application,
            MqttServerService mqttServerService,
            MqttSettingsModel mqttSettings)
@@ -27,7 +27,10 @@
            "IPv4": "*",
            "IPv6": "*",
            "Port": 8883,
-            "CertificatePath": "/absolute/path/to/pfx"
+            "Certificate": {
+                "Path": "/absolute/path/to/pfx",
+                "Password": ""
+            }
        },
        "WebSocketEndPoint": {
            "Enabled": true,
@@ -49,11 +52,7 @@
    },
    "Scripting": {
        "ScriptsPath": "Scripts",
-        "IncludePaths": [
-            "Lib",
-            "/usr/lib/python2.7",
-            "C:\\Python27\\Lib"
-        ]
+        "IncludePaths": []
    },
    "Logging": {
        "LogLevel": {
@@ -63,4 +62,4 @@
        }
    },
    "AllowedHosts": "*"
-}
+}
@@ -1,12 +0,0 @@
-{
-  "version": "1.0.0",
-  "name": "mqtt.test",
-  "private": true,
-  "devDependencies": {},
-  "dependencies": {
-    "@types/node": "^8.0.46",
-    "mqtt": "^2.15.1",
-    "systemjs": "^0.20.19",
-    "typescript": "^2.3.4"
-  }
-}
@@ -5,6 +5,6 @@ namespace MQTTnet.Adapter
 {
    public interface IMqttClientAdapterFactory
    {
-        IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetChildLogger logger);
+        IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetLogger logger);
    }
 }
@@ -1,3 +1,9 @@
+using MQTTnet.Channel;
+using MQTTnet.Diagnostics;
+using MQTTnet.Exceptions;
+using MQTTnet.Formatter;
+using MQTTnet.Internal;
+using MQTTnet.Packets;
 using System;
 using System.IO;
 using System.Net.Sockets;
@@ -5,34 +11,26 @@ using System.Runtime.InteropServices;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Channel;
-using MQTTnet.Diagnostics;
-using MQTTnet.Exceptions;
-using MQTTnet.Formatter;
-using MQTTnet.Internal;
-using MQTTnet.Packets;

 namespace MQTTnet.Adapter
 {
-    public class MqttChannelAdapter : IMqttChannelAdapter
+    public sealed class MqttChannelAdapter : Disposable, IMqttChannelAdapter
    {
-        private const uint ErrorOperationAborted = 0x800703E3;
-        private const int ReadBufferSize = 4096;  // TODO: Move buffer size to config
+        const uint ErrorOperationAborted = 0x800703E3;
+        const int ReadBufferSize = 4096;  // TODO: Move buffer size to config

-        private readonly SemaphoreSlim _writerSemaphore = new SemaphoreSlim(1, 1);
+        readonly IMqttNetLogger _logger;
+        readonly IMqttChannel _channel;
+        readonly MqttPacketReader _packetReader;

-        private readonly IMqttNetChildLogger _logger;
-        private readonly IMqttChannel _channel;
-        private readonly MqttPacketReader _packetReader;
+        readonly byte[] _fixedHeaderBuffer = new byte[2];

-        private readonly byte[] _fixedHeaderBuffer = new byte[2];
+        SemaphoreSlim _writerSemaphore = new SemaphoreSlim(1, 1);

-        private bool _isDisposed;
+        long _bytesReceived;
+        long _bytesSent;

-        private long _bytesReceived;
-        private 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));

@@ -57,7 +55,7 @@ namespace MQTTnet.Adapter

        public Action ReadingPacketStartedCallback { get; set; }
        public Action ReadingPacketCompletedCallback { get; set; }
-            
+
        public async Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
        {
            ThrowIfDisposed();
@@ -145,7 +143,7 @@ namespace MQTTnet.Adapter
            }
            finally
            {
-                _writerSemaphore.Release();
+                _writerSemaphore?.Release();
            }
        }

@@ -209,7 +207,20 @@ namespace MQTTnet.Adapter
            Interlocked.Exchange(ref _bytesSent, 0L);
        }

-        private async Task<ReceivedMqttPacket> ReceiveAsync(CancellationToken cancellationToken)
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                _channel?.Dispose();
+
+                _writerSemaphore?.Dispose();
+                _writerSemaphore = null;
+            }
+
+            base.Dispose(disposing);
+        }
+
+        async Task<ReceivedMqttPacket> ReceiveAsync(CancellationToken cancellationToken)
        {
            var readFixedHeaderResult = await _packetReader.ReadFixedHeaderAsync(_fixedHeaderBuffer, cancellationToken).ConfigureAwait(false);

@@ -269,29 +280,14 @@ namespace MQTTnet.Adapter
            }
        }

-        public void Dispose()
-        {
-            _isDisposed = true;
-
-            _channel?.Dispose();
-        }
-
-        private void ThrowIfDisposed()
-        {
-            if (_isDisposed)
-            {
-                throw new ObjectDisposedException(nameof(MqttChannelAdapter));
-            }
-        }
-
-        private static bool IsWrappedException(Exception exception)
+        static bool IsWrappedException(Exception exception)
        {
            return exception is OperationCanceledException ||
                   exception is MqttCommunicationTimedOutException ||
                   exception is MqttCommunicationException;
        }

-        private static void WrapException(Exception exception)
+        static void WrapException(Exception exception)
        {
            if (exception is IOException && exception.InnerException is SocketException innerException)
            {
@@ -5,12 +5,13 @@ namespace MQTTnet.Adapter
 {
    public class MqttConnectingFailedException : MqttCommunicationException
    {
-        public MqttConnectingFailedException(MqttClientConnectResultCode resultCode)
-            : base($"Connecting with MQTT server failed ({resultCode.ToString()}).")
+        public MqttConnectingFailedException(MqttClientAuthenticateResult result)
+            : base($"Connecting with MQTT server failed ({result.ResultCode.ToString()}).")
        {
-            ResultCode = resultCode;
+            Result = result;
        }

-        public MqttClientConnectResultCode ResultCode { get; }
+        public MqttClientAuthenticateResult Result { get; }
+        public MqttClientConnectResultCode ResultCode => Result.ResultCode;
    }
 }
@@ -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;
@@ -17,26 +13,34 @@ 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
 {
-    public class MqttClient : IMqttClient
+    public class MqttClient : Disposable, IMqttClient
    {
-        private readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
-        private readonly MqttPacketDispatcher _packetDispatcher = new MqttPacketDispatcher();
-        private readonly Stopwatch _sendTracker = new Stopwatch();
-        private readonly object _disconnectLock = new object();
+        readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
+        readonly MqttPacketDispatcher _packetDispatcher = new MqttPacketDispatcher();
+        readonly Stopwatch _sendTracker = new Stopwatch();
+        readonly Stopwatch _receiveTracker = new Stopwatch();
+        readonly object _disconnectLock = new object();

-        private readonly IMqttClientAdapterFactory _adapterFactory;
-        private readonly IMqttNetChildLogger _logger;
+        readonly IMqttClientAdapterFactory _adapterFactory;
+        readonly IMqttNetLogger _logger;

-        private CancellationTokenSource _backgroundCancellationTokenSource;
-        private Task _packetReceiverTask;
-        private Task _keepAlivePacketsSenderTask;
+        CancellationTokenSource _backgroundCancellationTokenSource;
+        Task _packetReceiverTask;
+        Task _keepAlivePacketsSenderTask;
+        Task _publishPacketReceiverTask;

-        private IMqttChannelAdapter _adapter;
-        private bool _cleanDisconnectInitiated;
-        private long _disconnectGate;
+        AsyncQueue<MqttPublishPacket> _publishPacketReceiverQueue;
+
+        IMqttChannelAdapter _adapter;
+        bool _cleanDisconnectInitiated;
+        long _disconnectGate;

        public MqttClient(IMqttClientAdapterFactory channelFactory, IMqttNetLogger logger)
        {
@@ -63,6 +67,8 @@ namespace MQTTnet.Client

            ThrowIfConnected("It is not allowed to connect with a server after the connection is established.");

+            ThrowIfDisposed();
+
            MqttClientAuthenticateResult authenticateResult = null;

            try
@@ -79,15 +85,22 @@ namespace MQTTnet.Client
                var adapter = _adapterFactory.CreateClientAdapter(options, _logger);
                _adapter = adapter;

-                _logger.Verbose($"Trying to connect with server '{options.ChannelOptions}' (Timeout={options.CommunicationTimeout}).");
-                await _adapter.ConnectAsync(options.CommunicationTimeout, cancellationToken).ConfigureAwait(false);
-                _logger.Verbose("Connection with server established.");
+                using (var combined = CancellationTokenSource.CreateLinkedTokenSource(backgroundCancellationToken, cancellationToken))
+                {
+                    _logger.Verbose($"Trying to connect with server '{options.ChannelOptions}' (Timeout={options.CommunicationTimeout}).");
+                    await _adapter.ConnectAsync(options.CommunicationTimeout, combined.Token).ConfigureAwait(false);
+                    _logger.Verbose("Connection with server established.");

-                _packetReceiverTask = Task.Run(() => TryReceivePacketsAsync(backgroundCancellationToken), backgroundCancellationToken);
+                    _publishPacketReceiverQueue = new AsyncQueue<MqttPublishPacket>();
+                    _publishPacketReceiverTask = Task.Run(() => ProcessReceivedPublishPackets(backgroundCancellationToken), backgroundCancellationToken);

-                authenticateResult = await AuthenticateAsync(adapter, options.WillMessage, cancellationToken).ConfigureAwait(false);
+                    _packetReceiverTask = Task.Run(() => TryReceivePacketsAsync(backgroundCancellationToken), backgroundCancellationToken);
+
+                    authenticateResult = await AuthenticateAsync(adapter, options.WillMessage, combined.Token).ConfigureAwait(false);
+                }

                _sendTracker.Restart();
+                _receiveTracker.Restart();

                if (Options.KeepAlivePeriod != TimeSpan.Zero)
                {
@@ -121,6 +134,10 @@ namespace MQTTnet.Client

        public async Task DisconnectAsync(MqttClientDisconnectOptions options, CancellationToken cancellationToken)
        {
+            if (options is null) throw new ArgumentNullException(nameof(options));
+
+            ThrowIfDisposed();
+
            try
            {
                _cleanDisconnectInitiated = true;
@@ -144,12 +161,15 @@ namespace MQTTnet.Client
        {
            if (data == null) throw new ArgumentNullException(nameof(data));

+            ThrowIfDisposed();
+            ThrowIfNotConnected();
+
            return SendAsync(new MqttAuthPacket
            {
                Properties = new MqttAuthPacketProperties
                {
                    // This must always be equal to the value from the CONNECT packet. So we use it here to ensure that.
-                    AuthenticationMethod = Options.AuthenticationMethod, 
+                    AuthenticationMethod = Options.AuthenticationMethod,
                    AuthenticationData = data.AuthenticationData,
                    ReasonString = data.ReasonString,
                    UserProperties = data.UserProperties
@@ -161,6 +181,7 @@ namespace MQTTnet.Client
        {
            if (options == null) throw new ArgumentNullException(nameof(options));

+            ThrowIfDisposed();
            ThrowIfNotConnected();

            var subscribePacket = _adapter.PacketFormatterAdapter.DataConverter.CreateSubscribePacket(options);
@@ -174,6 +195,7 @@ namespace MQTTnet.Client
        {
            if (options == null) throw new ArgumentNullException(nameof(options));

+            ThrowIfDisposed();
            ThrowIfNotConnected();

            var unsubscribePacket = _adapter.PacketFormatterAdapter.DataConverter.CreateUnsubscribePacket(options);
@@ -189,6 +211,7 @@ namespace MQTTnet.Client

            MqttTopicValidator.ThrowIfInvalid(applicationMessage.Topic);

+            ThrowIfDisposed();
            ThrowIfNotConnected();

            var publishPacket = _adapter.PacketFormatterAdapter.DataConverter.CreatePublishPacket(applicationMessage);
@@ -214,17 +237,32 @@ namespace MQTTnet.Client
            }
        }

-        public void Dispose()
+        void Cleanup()
        {
            _backgroundCancellationTokenSource?.Cancel(false);
            _backgroundCancellationTokenSource?.Dispose();
            _backgroundCancellationTokenSource = null;

+            _publishPacketReceiverQueue?.Dispose();
+            _publishPacketReceiverQueue = null;
+
            _adapter?.Dispose();
-            _adapter = null;
        }

-        private async Task<MqttClientAuthenticateResult> AuthenticateAsync(IMqttChannelAdapter channelAdapter, MqttApplicationMessage willApplicationMessage, CancellationToken cancellationToken)
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                Cleanup();
+
+                DisconnectedHandler = null;
+            }
+
+            base.Dispose(disposing);
+        }
+
+        async Task<MqttClientAuthenticateResult> AuthenticateAsync(IMqttChannelAdapter channelAdapter, MqttApplicationMessage willApplicationMessage, CancellationToken cancellationToken)
        {
            var connectPacket = channelAdapter.PacketFormatterAdapter.DataConverter.CreateConnectPacket(
                willApplicationMessage,
@@ -235,7 +273,7 @@ namespace MQTTnet.Client

            if (result.ResultCode != MqttClientConnectResultCode.Success)
            {
-                throw new MqttConnectingFailedException(result.ResultCode);
+                throw new MqttConnectingFailedException(result);
            }

            _logger.Verbose("Authenticated MQTT connection with server established.");
@@ -243,22 +281,21 @@ namespace MQTTnet.Client
            return result;
        }

-        private void ThrowIfNotConnected()
+        void ThrowIfNotConnected()
        {
            if (!IsConnected || Interlocked.Read(ref _disconnectGate) == 1) throw new MqttCommunicationException("The client is not connected.");
        }

-        private void ThrowIfConnected(string message)
+        void ThrowIfConnected(string message)
        {
            if (IsConnected) throw new MqttProtocolViolationException(message);
        }

-        private async Task DisconnectInternalAsync(Task sender, Exception exception, MqttClientAuthenticateResult authenticateResult)
+        async Task DisconnectInternalAsync(Task sender, Exception exception, MqttClientAuthenticateResult authenticateResult)
        {
            var clientWasConnected = IsConnected;

-            InitiateDisconnect();
-
+            TryInitiateDisconnect();
            IsConnected = false;

            try
@@ -269,18 +306,30 @@ namespace MQTTnet.Client
                    await _adapter.DisconnectAsync(Options.CommunicationTimeout, CancellationToken.None).ConfigureAwait(false);
                }

-                await WaitForTaskAsync(_packetReceiverTask, sender).ConfigureAwait(false);
-                await WaitForTaskAsync(_keepAlivePacketsSenderTask, sender).ConfigureAwait(false);
-
                _logger.Verbose("Disconnected from adapter.");
            }
            catch (Exception adapterException)
            {
                _logger.Warning(adapterException, "Error while disconnecting from adapter.");
            }
+
+            try
+            {
+                var receiverTask = WaitForTaskAsync(_packetReceiverTask, sender);
+                var publishPacketReceiverTask = WaitForTaskAsync(_publishPacketReceiverTask, sender);
+                var keepAliveTask = WaitForTaskAsync(_keepAlivePacketsSenderTask, sender);
+
+                await Task.WhenAll(receiverTask, publishPacketReceiverTask, keepAliveTask).ConfigureAwait(false);
+
+                _publishPacketReceiverQueue.Dispose();
+            }
+            catch (Exception e)
+            {
+                _logger.Warning(e, "Error while waiting for internal tasks.");
+            }
            finally
            {
-                Dispose();
+                Cleanup();
                _cleanDisconnectInitiated = false;

                _logger.Info("Disconnected.");
@@ -295,7 +344,7 @@ namespace MQTTnet.Client
            }
        }

-        private void InitiateDisconnect()
+        void TryInitiateDisconnect()
        {
            lock (_disconnectLock)
            {
@@ -327,7 +376,7 @@ namespace MQTTnet.Client
            return _adapter.SendPacketAsync(packet, Options.CommunicationTimeout, cancellationToken);
        }

-        private async Task<TResponsePacket> SendAndReceiveAsync<TResponsePacket>(MqttBasePacket requestPacket, CancellationToken cancellationToken) where TResponsePacket : MqttBasePacket
+        async Task<TResponsePacket> SendAndReceiveAsync<TResponsePacket>(MqttBasePacket requestPacket, CancellationToken cancellationToken) where TResponsePacket : MqttBasePacket
        {
            cancellationToken.ThrowIfCancellationRequested();

@@ -344,17 +393,32 @@ namespace MQTTnet.Client
                try
                {
                    await _adapter.SendPacketAsync(requestPacket, Options.CommunicationTimeout, cancellationToken).ConfigureAwait(false);
-                    return await packetAwaiter.WaitOneAsync(Options.CommunicationTimeout).ConfigureAwait(false);
                }
-                catch (MqttCommunicationTimedOutException)
+                catch (Exception e)
                {
-                    _logger.Warning(null, "Timeout while waiting for packet of type '{0}'.", typeof(TResponsePacket).Name);
+                    _logger.Warning(e, "Error when sending packet of type '{0}'.", typeof(TResponsePacket).Name);
+                    packetAwaiter.Cancel();
+                }
+
+                try
+                {
+                    var response = await packetAwaiter.WaitOneAsync(Options.CommunicationTimeout).ConfigureAwait(false);
+                    _receiveTracker.Restart();
+                    return response;
+                }
+                catch (Exception exception)
+                {
+                    if (exception is MqttCommunicationTimedOutException)
+                    {
+                        _logger.Warning(null, "Timeout while waiting for packet of type '{0}'.", typeof(TResponsePacket).Name);
+                    }
+
                    throw;
                }
            }
        }

-        private async Task TrySendKeepAliveMessagesAsync(CancellationToken cancellationToken)
+        async Task TrySendKeepAliveMessagesAsync(CancellationToken cancellationToken)
        {
            try
            {
@@ -369,14 +433,14 @@ namespace MQTTnet.Client
                        keepAliveSendInterval = Options.KeepAliveSendInterval.Value;
                    }

-                    var waitTime = keepAliveSendInterval - _sendTracker.Elapsed;
-                    if (waitTime <= TimeSpan.Zero)
+                    var waitTimeSend = keepAliveSendInterval - _sendTracker.Elapsed;
+                    var waitTimeReceive = keepAliveSendInterval - _receiveTracker.Elapsed;
+                    if (waitTimeSend <= TimeSpan.Zero || waitTimeReceive <= TimeSpan.Zero)
                    {
                        await SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket(), cancellationToken).ConfigureAwait(false);
-                        waitTime = keepAliveSendInterval;
                    }

-                    await Task.Delay(waitTime, cancellationToken).ConfigureAwait(false);
+                    await Task.Delay(keepAliveSendInterval, cancellationToken).ConfigureAwait(false);
                }
            }
            catch (Exception exception)
@@ -391,11 +455,11 @@ namespace MQTTnet.Client
                }
                else if (exception is MqttCommunicationException)
                {
-                    _logger.Warning(exception, "MQTT communication exception while sending/receiving keep alive packets.");
+                    _logger.Warning(exception, "Communication error while sending/receiving keep alive packets.");
                }
                else
                {
-                    _logger.Error(exception, "Unhandled exception while sending/receiving keep alive packets.");
+                    _logger.Error(exception, "Error exception while sending/receiving keep alive packets.");
                }

                if (!DisconnectIsPending())
@@ -409,7 +473,7 @@ namespace MQTTnet.Client
            }
        }

-        private async Task TryReceivePacketsAsync(CancellationToken cancellationToken)
+        async Task TryReceivePacketsAsync(CancellationToken cancellationToken)
        {
            try
            {
@@ -449,11 +513,11 @@ namespace MQTTnet.Client
                }
                else if (exception is MqttCommunicationException)
                {
-                    _logger.Warning(exception, "MQTT communication exception while receiving packets.");
+                    _logger.Warning(exception, "Communication error while receiving packets.");
                }
                else
                {
-                    _logger.Error(exception, "Unhandled exception while receiving packets.");
+                    _logger.Error(exception, "Error while receiving packets.");
                }

                _packetDispatcher.Dispatch(exception);
@@ -469,13 +533,15 @@ namespace MQTTnet.Client
            }
        }

-        private async Task TryProcessReceivedPacketAsync(MqttBasePacket packet, CancellationToken cancellationToken)
+        async Task TryProcessReceivedPacketAsync(MqttBasePacket packet, CancellationToken cancellationToken)
        {
            try
            {
+                _receiveTracker.Restart();
+
                if (packet is MqttPublishPacket publishPacket)
                {
-                    await TryProcessReceivedPublishPacketAsync(publishPacket, cancellationToken).ConfigureAwait(false);
+                    EnqueueReceivedPublishPacket(publishPacket);
                }
                else if (packet is MqttPubRelPacket pubRelPacket)
                {
@@ -521,11 +587,11 @@ namespace MQTTnet.Client
                }
                else if (exception is MqttCommunicationException)
                {
-                    _logger.Warning(exception, "MQTT communication exception while receiving packets.");
+                    _logger.Warning(exception, "Communication error while receiving packets.");
                }
                else
                {
-                    _logger.Error(exception, "Unhandled exception while receiving packets.");
+                    _logger.Error(exception, "Error while receiving packets.");
                }

                _packetDispatcher.Dispatch(exception);
@@ -537,64 +603,88 @@ namespace MQTTnet.Client
            }
        }

-        private async Task TryProcessReceivedPublishPacketAsync(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
+        void EnqueueReceivedPublishPacket(MqttPublishPacket publishPacket)
        {
            try
            {
-                if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtMostOnce)
-                {
-                    await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false);
-                }
-                else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtLeastOnce)
-                {
-                    if (await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false))
-                    {
-                        await SendAsync(new MqttPubAckPacket
-                        {
-                            PacketIdentifier = publishPacket.PacketIdentifier,
-                            ReasonCode = MqttPubAckReasonCode.Success
-                        }, cancellationToken).ConfigureAwait(false);
-                    }
-                }
-                else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.ExactlyOnce)
-                {
-                    if (await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false))
-                    {
-                        var pubRecPacket = new MqttPubRecPacket
-                        {
-                            PacketIdentifier = publishPacket.PacketIdentifier,
-                            ReasonCode = MqttPubRecReasonCode.Success
-                        };
-
-                        await SendAsync(pubRecPacket, cancellationToken).ConfigureAwait(false);
-                    }                    
-                }
-                else
-                {
-                    throw new MqttProtocolViolationException("Received a not supported QoS level.");
-                }
+                _publishPacketReceiverQueue.Enqueue(publishPacket);
            }
            catch (Exception exception)
            {
-                _logger.Error(exception, "Unhandled exception while handling application message.");
+                _logger.Error(exception, "Error while enqueueing application message.");
            }
        }

-        private async Task<MqttClientPublishResult> PublishAtMostOnce(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
+        async Task ProcessReceivedPublishPackets(CancellationToken cancellationToken)
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                try
+                {
+                    var publishPacketDequeueResult = await _publishPacketReceiverQueue.TryDequeueAsync(cancellationToken);
+
+                    if (!publishPacketDequeueResult.IsSuccess)
+                    {
+                        return;
+                    }
+
+                    var publishPacket = publishPacketDequeueResult.Item;
+
+                    if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtMostOnce)
+                    {
+                        await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false);
+                    }
+                    else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtLeastOnce)
+                    {
+                        if (await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false))
+                        {
+                            await SendAsync(new MqttPubAckPacket
+                            {
+                                PacketIdentifier = publishPacket.PacketIdentifier,
+                                ReasonCode = MqttPubAckReasonCode.Success
+                            }, cancellationToken).ConfigureAwait(false);
+                        }
+                    }
+                    else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.ExactlyOnce)
+                    {
+                        if (await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false))
+                        {
+                            var pubRecPacket = new MqttPubRecPacket
+                            {
+                                PacketIdentifier = publishPacket.PacketIdentifier,
+                                ReasonCode = MqttPubRecReasonCode.Success
+                            };
+
+                            await SendAsync(pubRecPacket, cancellationToken).ConfigureAwait(false);
+                        }
+                    }
+                    else
+                    {
+                        throw new MqttProtocolViolationException("Received a not supported QoS level.");
+                    }
+                }
+                catch (Exception exception)
+                {
+                    _logger.Error(exception, "Error while handling application message.");
+                }
+            }
+        }
+
+        async Task<MqttClientPublishResult> PublishAtMostOnce(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
        {
            // No packet identifier is used for QoS 0 [3.3.2.2 Packet Identifier]
            await SendAsync(publishPacket, cancellationToken).ConfigureAwait(false);
            return _adapter.PacketFormatterAdapter.DataConverter.CreatePublishResult(null);
        }

-        private async Task<MqttClientPublishResult> PublishAtLeastOnceAsync(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
+        async Task<MqttClientPublishResult> PublishAtLeastOnceAsync(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
        {
            publishPacket.PacketIdentifier = _packetIdentifierProvider.GetNextPacketIdentifier();
            var response = await SendAndReceiveAsync<MqttPubAckPacket>(publishPacket, cancellationToken).ConfigureAwait(false);
            return _adapter.PacketFormatterAdapter.DataConverter.CreatePublishResult(response);
        }

-        private async Task<MqttClientPublishResult> PublishExactlyOnceAsync(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
+        async Task<MqttClientPublishResult> PublishExactlyOnceAsync(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
        {
            publishPacket.PacketIdentifier = _packetIdentifierProvider.GetNextPacketIdentifier();

@@ -611,7 +701,7 @@ namespace MQTTnet.Client
            return _adapter.PacketFormatterAdapter.DataConverter.CreatePublishResult(pubRecPacket, pubCompPacket);
        }

-        private async Task<bool> HandleReceivedApplicationMessageAsync(MqttPublishPacket publishPacket)
+        async Task<bool> HandleReceivedApplicationMessageAsync(MqttPublishPacket publishPacket)
        {
            var applicationMessage = _adapter.PacketFormatterAdapter.DataConverter.CreateApplicationMessage(publishPacket);

@@ -626,15 +716,25 @@ namespace MQTTnet.Client
            return true;
        }

-        private static async Task WaitForTaskAsync(Task task, Task sender)
+        async Task WaitForTaskAsync(Task task, Task sender)
        {
-            if (task == sender || task == null)
+            if (task == null)
            {
                return;
            }

-            if (task.IsCanceled || task.IsCompleted || task.IsFaulted)
+            if (task == sender)
            {
+                // Return here to avoid deadlocks, but first any eventual exception in the task
+                // must be handled to avoid not getting an unhandled task exception
+                if (!task.IsFaulted)
+                {
+                    return;
+                }
+
+                // By accessing the Exception property the exception is considered handled and will
+                // not result in an unhandled task exception later by the finalizer
+                _logger.Warning(task.Exception, "Error while waiting for background task.");
                return;
            }

@@ -647,9 +747,9 @@ namespace MQTTnet.Client
            }
        }

-        private bool DisconnectIsPending()
+        bool DisconnectIsPending()
        {
            return Interlocked.CompareExchange(ref _disconnectGate, 1, 0) != 0;
        }
    }
-}
+}
@@ -1,8 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Client.Connecting;
+using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
 using MQTTnet.Client.ExtendedAuthenticationExchange;
 using MQTTnet.Client.Options;
@@ -11,6 +7,10 @@ using MQTTnet.Client.Receiving;
 using MQTTnet.Client.Subscribing;
 using MQTTnet.Client.Unsubscribing;
 using MQTTnet.Protocol;
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;

 namespace MQTTnet.Client
 {
@@ -128,7 +128,7 @@ namespace MQTTnet.Client
        {
            if (client == null) throw new ArgumentNullException(nameof(client));

-            return client.DisconnectAsync(null);
+            return client.DisconnectAsync(new MqttClientDisconnectOptions());
        }

        public static Task<MqttClientSubscribeResult> SubscribeAsync(this IMqttClient client, params TopicFilter[] topicFilters)
@@ -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;
-        private MqttClientWebSocketOptions _webSocketOptions;
-        private MqttClientOptionsBuilderTlsParameters _tlsParameters;
-        private MqttClientWebSocketProxyOptions _proxyOptions;
+        MqttClientTcpOptions _tcpOptions;
+        MqttClientWebSocketOptions _webSocketOptions;
+        MqttClientOptionsBuilderTlsParameters _tlsParameters;
+        MqttClientWebSocketProxyOptions _proxyOptions;

        public MqttClientOptionsBuilder WithProtocolVersion(MqttProtocolVersion value)
        {
@@ -139,6 +139,13 @@ namespace MQTTnet.Client.Options
            return this;
        }

+        public MqttClientOptionsBuilder WithCredentials(IMqttClientCredentials credentials)
+        {
+            _options.Credentials = credentials;
+
+            return this;
+        }
+
        public MqttClientOptionsBuilder WithExtendedAuthenticationExchangeHandler(IMqttExtendedAuthenticationExchangeHandler handler)
        {
            _options.ExtendedAuthenticationExchangeHandler = handler;
@@ -249,7 +256,11 @@ namespace MQTTnet.Client.Options
                        UseTls = true,
                        SslProtocol = _tlsParameters.SslProtocol,
                        AllowUntrustedCertificates = _tlsParameters.AllowUntrustedCertificates,
+#if WINDOWS_UWP
                        Certificates = _tlsParameters.Certificates?.Select(c => c.ToArray()).ToList(),
+#else
+                        Certificates = _tlsParameters.Certificates?.ToList(),
+#endif
                        CertificateValidationCallback = _tlsParameters.CertificateValidationCallback,
                        IgnoreCertificateChainErrors = _tlsParameters.IgnoreCertificateChainErrors,
                        IgnoreCertificateRevocationErrors = _tlsParameters.IgnoreCertificateRevocationErrors
@@ -18,7 +18,12 @@ namespace MQTTnet.Client.Options

        public SslProtocols SslProtocol { get; set; } = SslProtocols.Tls12;

+#if WINDOWS_UWP
        public IEnumerable<IEnumerable<byte>> Certificates { get; set; }
+#else
+        public IEnumerable<X509Certificate> Certificates { get; set; }
+#endif
+        

        public bool AllowUntrustedCertificates { get; set; }

@@ -15,8 +15,11 @@ namespace MQTTnet.Client.Options
        public bool IgnoreCertificateChainErrors { get; set; }

        public bool AllowUntrustedCertificates { get; set; }
-
+#if WINDOWS_UWP
        public List<byte[]> Certificates { get; set; }
+#else
+        public List<X509Certificate> Certificates { get; set; }
+#endif

        public SslProtocols SslProtocol { get; set; } = SslProtocols.Tls12;

@@ -0,0 +1,59 @@
+using MQTTnet.Packets;
+using System;
+using System.Collections.Generic;
+
+namespace MQTTnet.Client.Unsubscribing
+{
+    public class MqttClientUnsubscribeOptionsBuilder
+    {
+        private readonly MqttClientUnsubscribeOptions _unsubscribeOptions = new MqttClientUnsubscribeOptions();
+
+        public MqttClientUnsubscribeOptionsBuilder WithUserProperty(string name, string value)
+        {
+            if (name is null) throw new ArgumentNullException(nameof(name));
+            if (value is null) throw new ArgumentNullException(nameof(value));
+
+            return WithUserProperty(new MqttUserProperty(name, value));
+        }
+
+        public MqttClientUnsubscribeOptionsBuilder WithUserProperty(MqttUserProperty userProperty)
+        {
+            if (userProperty is null) throw new ArgumentNullException(nameof(userProperty));
+
+            if (_unsubscribeOptions.UserProperties is null)
+            {
+                _unsubscribeOptions.UserProperties = new List<MqttUserProperty>();
+            }
+
+            _unsubscribeOptions.UserProperties.Add(userProperty);
+
+            return this;
+        }
+
+        public MqttClientUnsubscribeOptionsBuilder WithTopicFilter(string topic)
+        {
+            if (topic is null) throw new ArgumentNullException(nameof(topic));
+
+            if (_unsubscribeOptions.TopicFilters is null)
+            {
+                _unsubscribeOptions.TopicFilters = new List<string>();
+            }
+
+            _unsubscribeOptions.TopicFilters.Add(topic);
+
+            return this;
+        }
+
+        public MqttClientUnsubscribeOptionsBuilder WithTopicFilter(TopicFilter topicFilter)
+        {
+            if (topicFilter is null) throw new ArgumentNullException(nameof(topicFilter));
+
+            return WithTopicFilter(topicFilter.Topic);
+        }
+
+        public MqttClientUnsubscribeOptions Build()
+        {
+            return _unsubscribeOptions;
+        }
+    }
+}
@@ -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);
-    }
-}
@@ -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);
    }
 }
@@ -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);
-        }
-    }
-}
@@ -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)
-        {
-            LogId = logId;
-            Timestamp = timestamp;
-            ThreadId = threadId;
-            Source = source;
-            Level = level;
-            Message = message;
-            Exception = exception;
-        }
+        public string LogId { get; set; }

-        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; }
+        public Exception Exception { get; set; }

        public override string ToString()
        {
@@ -6,9 +6,16 @@ namespace MQTTnet.Diagnostics
    {
        public MqttNetLogMessagePublishedEventArgs(MqttNetLogMessage logMessage)
        {
+            LogMessage = logMessage ?? throw new ArgumentNullException(nameof(logMessage));
+
+#pragma warning disable CS0618 // Type or member is obsolete
            TraceMessage = logMessage ?? throw new ArgumentNullException(nameof(logMessage));
+#pragma warning restore CS0618 // Type or member is obsolete
        }

+        [Obsolete("Use new proeprty LogMessage instead.")]
        public MqttNetLogMessage TraceMessage { get; }
+
+        public MqttNetLogMessage LogMessage { get; }
    }
 }
@@ -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);
        }
    }
 }
@@ -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);
+        }
+    }
+}
@@ -1,6 +1,6 @@
 namespace MQTTnet.Diagnostics
 {
-    public static class TargetFrameworkInfoProvider
+    public static class TargetFrameworkProvider
    {
        public static string TargetFramework
        {
@@ -0,0 +1,21 @@
+using System;
+
+namespace MQTTnet.Exceptions
+{
+    public class MqttConfigurationException : Exception
+    {
+        protected MqttConfigurationException()
+        {
+        }
+
+        public MqttConfigurationException(Exception innerException)
+            : base(innerException.Message, innerException)
+        {
+        }
+
+        public MqttConfigurationException(string message)
+            : base(message)
+        {
+        }
+    }
+}
@@ -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));
+        }
+    }
+}
@@ -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;
+        }
+    }
+}
@@ -5,15 +5,25 @@
        int Length { get; }

        void WriteWithLengthPrefix(string value);
-        void Write(byte returnCode);
-        void WriteWithLengthPrefix(byte[] payload);
-        void Write(ushort keepAlivePeriod);
-        void Write(IMqttPacketWriter propertyWriter);
-        void WriteVariableLengthInteger(uint length);
-        void Write(byte[] payload, int v, int length);
-        void Reset(int v);
-        void Seek(int v);
+
+        void Write(byte value);
+
+        void WriteWithLengthPrefix(byte[] value);
+
+        void Write(ushort value);
+
+        void Write(IMqttPacketWriter value);
+
+        void WriteVariableLengthInteger(uint value);
+
+        void Write(byte[] value, int offset, int length);
+
+        void Reset(int length);
+
+        void Seek(int offset);
+
        void FreeBuffer();
+
        byte[] GetBuffer();
    }
 }
@@ -21,8 +21,6 @@ namespace MQTTnet.Formatter
        {
            // The MQTT fixed header contains 1 byte of flags and at least 1 byte for the remaining data length.
            // So in all cases at least 2 bytes must be read for a complete MQTT packet.
-            // async/await is used here because the next packet is received in a couple of minutes so the performance
-            // impact is acceptable according to a useless waiting thread.
            var buffer = fixedHeaderBuffer;
            var totalBytesRead = 0;

@@ -55,16 +53,7 @@ namespace MQTTnet.Formatter
                };
            }

-#if WINDOWS_UWP
-            // UWP will have a dead lock when calling this not async.
            var bodyLength = await ReadBodyLengthAsync(buffer[1], cancellationToken).ConfigureAwait(false);
-#else
-            // Here the async/await pattern is not used because the overhead of context switches
-            // is too big for reading 1 byte in a row. We expect that the remaining data was sent
-            // directly after the initial bytes. If the client disconnects just in this moment we
-            // will get an exception anyway.
-            var bodyLength = ReadBodyLength(buffer[1], cancellationToken);
-#endif

            if (!bodyLength.HasValue)
            {
@@ -81,49 +70,6 @@ namespace MQTTnet.Formatter
            };
        }

-#if !WINDOWS_UWP
-        private int? ReadBodyLength(byte initialEncodedByte, CancellationToken cancellationToken)
-        {
-            var offset = 0;
-            var multiplier = 128;
-            var value = initialEncodedByte & 127;
-            int encodedByte = initialEncodedByte;
-
-            while ((encodedByte & 128) != 0)
-            {
-                offset++;
-                if (offset > 3)
-                {
-                    throw new MqttProtocolViolationException("Remaining length is invalid.");
-                }
-
-                if (cancellationToken.IsCancellationRequested)
-                {
-                    return null;
-                }
-
-                var readCount = _channel.ReadAsync(_singleByteBuffer, 0, 1, cancellationToken).GetAwaiter().GetResult();
-
-                if (cancellationToken.IsCancellationRequested)
-                {
-                    return null;
-                }
-
-                if (readCount == 0)
-                {
-                    return null;
-                }
-
-                encodedByte = _singleByteBuffer[0];
-
-                value += (encodedByte & 127) * multiplier;
-                multiplier *= 128;
-            }
-
-            return value;
-        }
-#else
-
        private async Task<int?> ReadBodyLengthAsync(byte initialEncodedByte, CancellationToken cancellationToken)
        {
            var offset = 0;
@@ -164,6 +110,5 @@ namespace MQTTnet.Formatter

            return value;
        }
-#endif
    }
 }
@@ -1,6 +1,4 @@
-using System;
-using System.Linq;
-using MQTTnet.Client.Connecting;
+using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
 using MQTTnet.Client.Options;
 using MQTTnet.Client.Publishing;
@@ -10,6 +8,8 @@ using MQTTnet.Exceptions;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
+using System;
+using System.Linq;
 using MqttClientSubscribeResult = MQTTnet.Client.Subscribing.MqttClientSubscribeResult;

 namespace MQTTnet.Formatter.V3
@@ -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,
@@ -158,7 +153,7 @@ namespace MQTTnet.Formatter.V3
        {
            if (unsubscribePacket == null) throw new ArgumentNullException(nameof(unsubscribePacket));
            if (unsubAckPacket == null) throw new ArgumentNullException(nameof(unsubAckPacket));
-            
+
            var result = new MqttClientUnsubscribeResult();

            result.Items.AddRange(unsubscribePacket.TopicFilters.Select((t, i) =>
@@ -171,14 +166,9 @@ 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);
-            
+
            return subscribePacket;
        }

@@ -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);

@@ -199,9 +184,9 @@ namespace MQTTnet.Formatter.V3

        public MqttDisconnectPacket CreateDisconnectPacket(MqttClientDisconnectOptions options)
        {
-            if (options != null)
+            if (options.ReasonCode != MqttClientDisconnectReason.NormalDisconnection || options.ReasonString != null)
            {
-                throw new MqttProtocolViolationException("Reason codes for disconnect are only supported for MQTTv5.");
+                throw new MqttProtocolViolationException("Reason codes and reason string for disconnect are only supported for MQTTv5.");
            }

            return new MqttDisconnectPacket();
@@ -139,7 +139,7 @@ namespace MQTTnet.Formatter.V5
                ReasonCode = connectionValidatorContext.ReasonCode,
                Properties = new MqttConnAckPacketProperties
                {
-                    UserProperties = connectionValidatorContext.UserProperties,
+                    UserProperties = connectionValidatorContext.ResponseUserProperties,
                    AuthenticationMethod = connectionValidatorContext.AuthenticationMethod,
                    AuthenticationData = connectionValidatorContext.ResponseAuthenticationData,
                    AssignedClientIdentifier = connectionValidatorContext.AssignedClientIdentifier,
@@ -328,10 +328,7 @@ namespace MQTTnet.Formatter.V5
            {
                ThrowReasonCodeNotSetException();
            }
-
-            packetWriter.Write(packet.PacketIdentifier.Value);
-            packetWriter.Write((byte)packet.ReasonCode.Value);
-
+           
            var propertiesWriter = new MqttV500PropertiesWriter();
            if (packet.Properties != null)
            {
@@ -339,6 +336,8 @@ namespace MQTTnet.Formatter.V5
                propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
            }

+            packetWriter.Write(packet.PacketIdentifier.Value);
+
            if (packetWriter.Length > 0 || packet.ReasonCode.Value != MqttPubRecReasonCode.Success)
            {
                packetWriter.Write((byte)packet.ReasonCode.Value);
@@ -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
+    }
+}
@@ -1,17 +1,17 @@
-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));
-            
+
            switch (options.ChannelOptions)
            {
                case MqttClientTcpOptions _:
--- a/Show More
+++ b/Show More