Merge branch 'develop'

Added dependents and MIT license badge to the readme.

Build/MQTTnet.AspNetCore.nuspec

@@ -17,6 +17,7 @@
       <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" />
     </dependencies>

Build/MQTTnet.Extensions.ManagedClient.nuspec

@@ -34,10 +34,9 @@
     <!-- .NET Framework -->
     <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\net452\MQTTnet.Extensions.ManagedClient.*" target="lib\net452\"/>
 
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\net461\"/>
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\net462\"/>
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\net470\"/>
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\net471\"/>
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\net472\"/>
+    <!-- .NET Framework 4.6.0 will use binaries from 4.5.2. -->
+    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\net461\MQTTnet.Extensions.Rpc.*" target="lib\net461\"/>
+
+    <!-- Everything above .NET Framework 4.6.1 will use the binaries from 4.6.1. -->
   </files>
 </package>

Build/MQTTnet.Extensions.Rpc.nuspec

@@ -34,10 +34,9 @@
     <!-- .NET Framework -->
     <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\net452\MQTTnet.Extensions.Rpc.*" target="lib\net452\"/>
 
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\net461\"/>
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\net462\"/>
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\net470\"/>
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\net471\"/>
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\net472\"/>
+    <!-- .NET Framework 4.6.0 will use binaries from 4.5.2. -->
+    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\net461\MQTTnet.Extensions.Rpc.*" target="lib\net461\"/>
+
+    <!-- Everything above .NET Framework 4.6.1 will use the binaries from 4.6.1. -->
   </files>
 </package>

Build/MQTTnet.Extensions.WebSocket4Net.nuspec

@@ -0,0 +1,42 @@
+<?xml version="1.0"?>
+<package >
+  <metadata>
+    <id>MQTTnet.Extensions.WebSocket4Net</id>
+    <version>0.0.0</version>
+    <authors>Christian Kratky</authors>
+    <owners>Christian Kratky</owners>
+    <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>
+    <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>
+    <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" />
+    </dependencies>
+  </metadata>
+
+  <files>
+    <!-- License -->
+    <file src="..\LICENSE" />
+
+    <!-- .NET Standard 1.3 -->
+    <file src="..\Source\MQTTnet.Extensions.WebSocket4Net\bin\Release\netstandard1.3\MQTTnet.Extensions.WebSocket4Net.*" target="lib\netstandard1.3\"/>
+
+    <!-- .NET Standard 2.0 -->
+    <file src="..\Source\MQTTnet.Extensions.WebSocket4Net\bin\Release\netstandard2.0\MQTTnet.Extensions.WebSocket4Net.*" target="lib\netstandard2.0\"/>
+
+    <!-- Universal Windows -->
+    <file src="..\Source\MQTTnet.Extensions.WebSocket4Net\bin\Release\uap10.0\MQTTnet.Extensions.WebSocket4Net.*" target="lib\uap10.0\"/>
+
+    <!-- .NET Framework -->
+    <file src="..\Source\MQTTnet.Extensions.WebSocket4Net\bin\Release\net452\MQTTnet.Extensions.WebSocket4Net.*" target="lib\net452\"/>
+
+    <!-- .NET Framework 4.6.0 will use binaries from 4.5.2. -->
+    <file src="..\Source\MQTTnet.Extensions.WebSocket4Net\bin\Release\net461\MQTTnet.Extensions.WebSocket4Net.*" target="lib\net461\"/>
+
+    <!-- Everything above .NET Framework 4.6.1 will use the binaries from 4.6.1. -->
+  </files>
+</package>

Build/MQTTnet.NETStandard.nuspec

@@ -9,7 +9,7 @@
     <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
     <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
     <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). This package contains the .NET Standard version of the library only.</description>
+    <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>
     <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> 

Build/MQTTnet.nuspec

@@ -9,37 +9,10 @@
     <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
     <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
     <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).</description>
+    <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] Added support for MQTTv5 packages.
-* [Core] Performance improvements.
-* [Core] Removed obsolete methods.
-* [Core] Fixed a memory leak when processing lots of messages (thanks to @tschanko)
-* [Core] Added more overloads for MQTT factory.
-* [Core] The client password is now hidden from the logs (replaced with **** if set).
-* [Core] Fixed a memory leak when using SSL connections (thanks to @biovoid). 
-* [Client] Added validation of topics before publishing.
-* [Client] Added new MQTTv5 features to options builder.
-* [Client] Added uniform API across all supported MQTT versions (BREAKING CHANGE!)
-* [Client] The client will now avoid sending an ACK if an exception has been thrown in message handler (thanks to @ramonsmits).
-* [Client] Fixed issues in QoS 2 handling which leads to message loss.
-* [Client] Replaced all events with proper async compatible handlers (BREAKING CHANGE!).
-* [Client] Added more configuration values to TCP endpoint options.
-* [ManagedClient] Replaced all events with proper async compatible handlers (BREAKING CHANGE!).
-* [ManagedClient] The log ID is now propagated to the internal client (thanks to @vbBerni).
-* [ManagedClient] Added validation of topics before publishing.
-* [ManagedClient] The internal MQTT client is now closed properly (thanks to @vbBerni).
-* [Server] Added support for MQTTv5 clients. The server will still return _success_ for all cases at the moment even if more granular codes are available.
-* [Server] Fixed issues in QoS 2 handling which leads to message loss.
-* [Server] Replaced all events with proper async compatible handlers (BREAKING CHANGE!).
-* [Server] The used logger instance is now propagated to the WebSocket server adapter.
-* [Server] Added the flag "IsSecureConnection" which is set to true when the connection is encrypted.
-* [Server] Fixed wrong will message behavior when stopping server (thanks to @JohBa)
-* [Server] Added validation of topics before publishing.
-* [Server] Added more configuration values to TCP endpoint options.
-* [MQTTnet Server] Added as first Alpha version of standalone cross platform MQTT server.
-
-* [Note] Due to MQTTv5 a lot of new classes were introduced. This required adding new namespaces as well. Most classes are backward compatible but new namespaces must be added.
+* [Core] Fixed wrong versions in nuget packages.
+* [Server] The TCP address is now reused when starting which should prevent "port in used" error when restarting.
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2019</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> 
@@ -59,10 +32,6 @@
       <group targetFramework="uap10.0">
         <dependency id="Microsoft.NETCore.UniversalWindowsPlatform" version="6.2.8" />
       </group>
-      <group targetFramework="net452">
-      </group>
-      <group targetFramework="net461">
-      </group>
     </dependencies>
   </metadata>
 
@@ -82,10 +51,9 @@
     <!-- .NET Framework -->
     <file src="..\Source\MQTTnet\bin\Release\net452\MQTTnet.*" target="lib\net452\"/>
 
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\net461\"/>
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\net462\"/>
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\net470\"/>
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\net471\"/>
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\net472\"/>
+    <!-- .NET Framework 4.6.0 will use binaries from 4.5.2. -->
+    <file src="..\Source\MQTTnet\bin\Release\net461\MQTTnet.*" target="lib\net461\"/>
+
+    <!-- Everything above .NET Framework 4.6.1 will use the binaries from 4.6.1. -->
   </files>
 </package>

Build/build.ps1

@@ -36,6 +36,17 @@ Write-Host
 &$msbuild ..\Source\MQTTnet.Extensions.ManagedClient\MQTTnet.Extensions.ManagedClient.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet.Extensions.ManagedClient\MQTTnet.Extensions.ManagedClient.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 the WebSocket4Net extension
+&$msbuild ..\Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net452" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
+&$msbuild ..\Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.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"
+&$msbuild ..\Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard1.3" /p:FileVersion=$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="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"
+
+# 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
@@ -44,6 +55,8 @@ Copy-Item MQTTnet.Extensions.Rpc.nuspec -Destination MQTTnet.Extensions.Rpc.nusp
 (Get-Content MQTTnet.Extensions.Rpc.nuspec) -replace '\$nugetVersion', $nugetVersion | Set-Content MQTTnet.Extensions.Rpc.nuspec
 Copy-Item MQTTnet.Extensions.ManagedClient.nuspec -Destination MQTTnet.Extensions.ManagedClient.nuspec.old -Force
 (Get-Content MQTTnet.Extensions.ManagedClient.nuspec) -replace '\$nugetVersion', $nugetVersion | Set-Content MQTTnet.Extensions.ManagedClient.nuspec
+Copy-Item MQTTnet.Extensions.WebSocket4Net.nuspec -Destination MQTTnet.Extensions.WebSocket4Net.nuspec.old -Force
+(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
@@ -51,7 +64,57 @@ New-Item -ItemType Directory -Force -Path .\NuGet
 .\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
 
 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.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
+
+####################################################################
+
+# 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) 
+
+####################################################################

Build/upload.ps1

@@ -1,9 +1,13 @@
 param([string]$apiKey)
 
+Invoke-WebRequest -Uri "https://dist.nuget.org/win-x86-commandline/latest/nuget.exe" -OutFile "nuget.exe"
+
 $files = Get-ChildItem -Path ".\NuGet" -Filter "*.nupkg"
 foreach ($file in $files)
 {
 	Write-Host "Uploading: " $file
 
 	.\nuget.exe push $file.Fullname $apiKey -NoSymbols -Source https://api.nuget.org/v3/index.json
-}
+}
+
+Remove-Item "nuget.exe" -Force -Recurse -ErrorAction SilentlyContinue

MQTTnet.noUWP.sln

@@ -47,6 +47,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Tests", "Tests\MQTT
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Server", "Source\MQTTnet.Server\MQTTnet.Server.csproj", "{DADEA836-5CC3-474C-A2D8-4D0F31118CD7}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Extensions.WebSocket4Net", "Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj", "{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -219,6 +221,22 @@ Global
 		{DADEA836-5CC3-474C-A2D8-4D0F31118CD7}.Release|x64.Build.0 = Release|Any CPU
 		{DADEA836-5CC3-474C-A2D8-4D0F31118CD7}.Release|x86.ActiveCfg = Release|Any CPU
 		{DADEA836-5CC3-474C-A2D8-4D0F31118CD7}.Release|x86.Build.0 = Release|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Debug|ARM.ActiveCfg = Debug|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Debug|ARM.Build.0 = Debug|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Debug|x64.Build.0 = Debug|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Debug|x86.Build.0 = Debug|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Release|ARM.ActiveCfg = Release|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Release|ARM.Build.0 = Release|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Release|x64.ActiveCfg = Release|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Release|x64.Build.0 = Release|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Release|x86.ActiveCfg = Release|Any CPU
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -234,6 +252,7 @@ Global
 		{61B62223-F5D0-48E4-BBD6-2CBA9353CB5E} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
 		{9C7106CA-96B8-4ABE-B3B4-9357AB8ACB41} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
 		{DADEA836-5CC3-474C-A2D8-4D0F31118CD7} = {32A630A7-2598-41D7-B625-204CD906F5FB}
+		{9AE2F8DA-4178-470B-B8C4-88BE1DAE7D5F} = {12816BCC-AF9E-44A9-9AE5-C246AF2A0587}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {07536672-5CBC-4BE3-ACE0-708A431A7894}

MQTTnet.sln

@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 16
-VisualStudioVersion = 16.0.28729.10
+VisualStudioVersion = 16.0.29009.5
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Tests", "Tests\MQTTnet.Core.Tests\MQTTnet.Tests.csproj", "{A7FF0C91-25DE-4BA6-B39E-F54E8DADF1CC}"
 EndProject
@@ -19,6 +19,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Build", "Build", "{67C28AC1
 		Build\MQTTnet.AspNetCore.nuspec = Build\MQTTnet.AspNetCore.nuspec
 		Build\MQTTnet.Extensions.ManagedClient.nuspec = Build\MQTTnet.Extensions.ManagedClient.nuspec
 		Build\MQTTnet.Extensions.Rpc.nuspec = Build\MQTTnet.Extensions.Rpc.nuspec
+		Build\MQTTnet.Extensions.WebSocket4Net.nuspec = Build\MQTTnet.Extensions.WebSocket4Net.nuspec
 		Build\MQTTnet.NETStandard.nuspec = Build\MQTTnet.NETStandard.nuspec
 		Build\MQTTnet.nuspec = Build\MQTTnet.nuspec
 		Build\upload.ps1 = Build\upload.ps1
@@ -50,6 +51,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.AspNetCore.Tests",
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Server", "Source\MQTTnet.Server\MQTTnet.Server.csproj", "{5699FB8C-838C-4AB0-80A5-9CA809F9B65B}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Extensions.WebSocket4Net", "Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj", "{2BD01D53-4CA5-4142-BE8D-313876395E3E}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -245,6 +248,22 @@ Global
 		{5699FB8C-838C-4AB0-80A5-9CA809F9B65B}.Release|x64.Build.0 = Release|Any CPU
 		{5699FB8C-838C-4AB0-80A5-9CA809F9B65B}.Release|x86.ActiveCfg = Release|Any CPU
 		{5699FB8C-838C-4AB0-80A5-9CA809F9B65B}.Release|x86.Build.0 = Release|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Debug|ARM.ActiveCfg = Debug|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Debug|ARM.Build.0 = Debug|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Debug|x64.Build.0 = Debug|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Debug|x86.Build.0 = Debug|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Release|Any CPU.Build.0 = Release|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Release|ARM.ActiveCfg = Release|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Release|ARM.Build.0 = Release|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Release|x64.ActiveCfg = Release|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Release|x64.Build.0 = Release|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Release|x86.ActiveCfg = Release|Any CPU
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -261,6 +280,7 @@ Global
 		{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}
+		{2BD01D53-4CA5-4142-BE8D-313876395E3E} = {12816BCC-AF9E-44A9-9AE5-C246AF2A0587}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {07536672-5CBC-4BE3-ACE0-708A431A7894}

README.md

@@ -8,7 +8,8 @@
 [![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)
+[![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)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://raw.githubusercontent.com/chkr1011/MQTTnet/master/LICENSE)
 
 # MQTTnet
 
@@ -26,7 +27,7 @@ MQTTnet is a high performance .NET library for MQTT based communication. It prov
 * Uniform API across all supported versions of the MQTT protocol
 * Interfaces included for mocking and testing
 * Access to internal trace messages
-* Unit tested (~150 tests)
+* Unit tested (~210 tests)
 * No external dependencies
 
 \* Tested on local machine (Intel i7 8700K) with MQTTnet client and server running in the same process using the TCP channel. The app for verification is part of this repository and stored in _/Tests/MQTTnet.TestApp.NetCore_.
@@ -104,6 +105,8 @@ 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

Source/MQTTnet.AspnetCore/ApplicationBuilderExtensions.cs

@@ -28,7 +28,7 @@ namespace MQTTnet.AspNetCore
                 }
 
                 var adapter = app.ApplicationServices.GetRequiredService<MqttWebSocketServerAdapter>();
-                using (var webSocket = await context.WebSockets.AcceptWebSocketAsync(subProtocol))
+                using (var webSocket = await context.WebSockets.AcceptWebSocketAsync(subProtocol).ConfigureAwait(false))
                 {
                     await adapter.RunWebSocketConnectionAsync(webSocket, context);
                 }

Source/MQTTnet.AspnetCore/Client/MqttClientConnectionContextFactory.cs

@@ -21,7 +21,10 @@ namespace MQTTnet.AspNetCore.Client
                     {
                         var endpoint = new DnsEndPoint(tcpOptions.Server, tcpOptions.GetPort());
                         var tcpConnection = new TcpConnection(endpoint);
-                        return new MqttConnectionContext(new MqttPacketFormatterAdapter(options.ProtocolVersion), tcpConnection);
+
+                        var writer = new SpanBasedMqttPacketWriter();
+                        var formatter = new MqttPacketFormatterAdapter(options.ProtocolVersion, writer);
+                        return new MqttConnectionContext(formatter, tcpConnection);
                     }
                 default:
                     {

Source/MQTTnet.AspnetCore/Client/Tcp/SocketSender.cs

@@ -5,6 +5,10 @@ using System.Diagnostics;
 using System.IO.Pipelines;
 using System.Net.Sockets;
 
+#if NETCOREAPP2_1
+using System.Runtime.InteropServices;
+#endif
+
 namespace MQTTnet.AspNetCore.Client.Tcp
 {
     public class SocketSender

Source/MQTTnet.AspnetCore/MQTTnet.AspNetCore.csproj

@@ -1,12 +1,13 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;netcoreapp2.1</TargetFrameworks>
     <Product />
     <Company />
     <Authors />
     <PackageId />
     <LangVersion>7.2</LangVersion>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
@@ -15,6 +16,7 @@
 
   <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>

Source/MQTTnet.AspnetCore/MqttConnectionContext.cs

@@ -1,13 +1,15 @@
 using Microsoft.AspNetCore.Connections;
+using Microsoft.AspNetCore.Http.Connections.Features;
 using MQTTnet.Adapter;
 using MQTTnet.AspNetCore.Client.Tcp;
 using MQTTnet.Exceptions;
+using MQTTnet.Formatter;
 using MQTTnet.Packets;
 using System;
 using System.IO.Pipelines;
+using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Formatter;
 
 namespace MQTTnet.AspNetCore
 {
@@ -17,36 +19,66 @@ namespace MQTTnet.AspNetCore
         {
             PacketFormatterAdapter = packetFormatterAdapter ?? throw new ArgumentNullException(nameof(packetFormatterAdapter));
             Connection = connection ?? throw new ArgumentNullException(nameof(connection));
+
+            if (Connection.Transport != null)
+            {
+                _input = Connection.Transport.Input;
+                _output = Connection.Transport.Output;
+            }
+            
+            _reader = new SpanBasedMqttPacketBodyReader();
         }
 
-        public string Endpoint => Connection.ConnectionId;
-        public bool IsSecureConnection => false; // TODO: Fix detection (WS vs. WSS).
+        private PipeReader _input;
+        private PipeWriter _output;
+        private readonly SpanBasedMqttPacketBodyReader _reader;
+
+        public string Endpoint
+        {
+            get
+            {
+                var connection = Http?.HttpContext?.Connection;
+                if (connection == null)
+                {
+                    return Connection.ConnectionId;
+                }
+
+                return $"{connection.RemoteIpAddress}:{connection.RemotePort}";
+            }
+        }
+
+        public bool IsSecureConnection => Http?.HttpContext?.Request?.IsHttps ?? false;
+
+        public X509Certificate2 ClientCertificate => Http?.HttpContext?.Connection?.ClientCertificate;
+
+        private IHttpContextFeature Http => Connection.Features.Get<IHttpContextFeature>();
 
         public ConnectionContext Connection { get; }
         public MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
 
-        public long BytesSent { get; } // TODO: Fix calculation.
-        public long BytesReceived { get; } // TODO: Fix calculation.
+        public long BytesSent { get; set; }
+        public long BytesReceived { get; set; }
 
         public Action ReadingPacketStartedCallback { get; set; }
         public Action ReadingPacketCompletedCallback { get; set; }
-        
+
         private readonly SemaphoreSlim _writerSemaphore = new SemaphoreSlim(1, 1);
 
-        public Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
+        public async Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
             if (Connection is TcpConnection tcp && !tcp.IsConnected)
             {
-                return tcp.StartAsync();
+                await tcp.StartAsync().ConfigureAwait(false);
             }
 
-            return Task.CompletedTask;
+            _input = Connection.Transport.Input;
+            _output = Connection.Transport.Output;
         }
 
         public Task DisconnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
-            Connection.Transport.Input.Complete();
-            Connection.Transport.Output.Complete();
+            _input?.Complete();
+            _output?.Complete();
 
             return Task.CompletedTask;
         }
@@ -79,8 +111,9 @@ namespace MQTTnet.AspNetCore
                     {
                         if (!buffer.IsEmpty)
                         {
-                            if (PacketFormatterAdapter.TryDecode(buffer, out var packet, out consumed, out observed))
+                            if (PacketFormatterAdapter.TryDecode(_reader, buffer, out var packet, out consumed, out observed, out var received))
                             {
+                                BytesReceived += received;
                                 return packet;
                             }
                             else
@@ -112,15 +145,28 @@ namespace MQTTnet.AspNetCore
             return null;
         }
 
+        public void ResetStatistics()
+        {
+            BytesReceived = 0;
+            BytesSent = 0;
+        }
+
         public async Task SendPacketAsync(MqttBasePacket packet, TimeSpan timeout, CancellationToken cancellationToken)
         {
-            var buffer = PacketFormatterAdapter.Encode(packet).AsMemory();
-            var output = Connection.Transport.Output;
+            var formatter = PacketFormatterAdapter;
+
 
             await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
             try
             {
-                await output.WriteAsync(buffer, cancellationToken).ConfigureAwait(false);
+                var buffer = formatter.Encode(packet);
+                var msg = buffer.AsMemory();
+                var output = _output;
+                msg.CopyTo(output.GetMemory(msg.Length));
+                BytesSent += msg.Length;
+                PacketFormatterAdapter.FreeBuffer();
+                output.Advance(msg.Length);
+                await output.FlushAsync().ConfigureAwait(false);
             }
             finally
             {

Source/MQTTnet.AspnetCore/MqttConnectionHandler.cs

@@ -10,7 +10,7 @@ namespace MQTTnet.AspNetCore
 {
     public class MqttConnectionHandler : ConnectionHandler, IMqttServerAdapter
     {
-        public Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
+        public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
 
         public override async Task OnConnectedAsync(ConnectionContext connection)
         {
@@ -21,12 +21,15 @@ namespace MQTTnet.AspNetCore
                 transferFormatFeature.ActiveFormat = TransferFormat.Binary;
             }
 
-            using (var adapter = new MqttConnectionContext(new MqttPacketFormatterAdapter(), connection))
+            var writer = new SpanBasedMqttPacketWriter();
+            var formatter = new MqttPacketFormatterAdapter(writer);
+            using (var adapter = new MqttConnectionContext(formatter, connection))
             {
-                var args = new MqttServerAdapterClientAcceptedEventArgs(adapter);
-                ClientAcceptedHandler?.Invoke(args);
-
-                await args.SessionTask.ConfigureAwait(false);
+                var clientHandler = ClientHandler;
+                if (clientHandler != null)
+                {
+                    await clientHandler(adapter).ConfigureAwait(false);
+                }
             }
         }
 

Source/MQTTnet.AspnetCore/MqttWebSocketServerAdapter.cs

@@ -21,7 +21,7 @@ namespace MQTTnet.AspNetCore
             _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
         }
 
-        public Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
+        public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
 
         public Task StartAsync(IMqttServerOptions options)
         {
@@ -40,18 +40,26 @@ namespace MQTTnet.AspNetCore
             var endpoint = $"{httpContext.Connection.RemoteIpAddress}:{httpContext.Connection.RemotePort}";
             
             var clientCertificate = await httpContext.Connection.GetClientCertificateAsync().ConfigureAwait(false);
-            var isSecureConnection = clientCertificate != null;
-            clientCertificate?.Dispose();
-
-            var channel = new MqttWebSocketChannel(webSocket, endpoint, isSecureConnection);
-            var channelAdapter = new MqttChannelAdapter(channel, new MqttPacketFormatterAdapter(), _logger.CreateChildLogger(nameof(MqttWebSocketServerAdapter)));
-
-            var eventArgs = new MqttServerAdapterClientAcceptedEventArgs(channelAdapter);
-            ClientAcceptedHandler?.Invoke(eventArgs);
-
-            if (eventArgs.SessionTask != null)
+            try
             {
-                await eventArgs.SessionTask.ConfigureAwait(false);
+                var isSecureConnection = clientCertificate != null;
+
+                var clientHandler = ClientHandler;
+                if (clientHandler != null)
+                {
+                    var writer = new SpanBasedMqttPacketWriter();
+                    var formatter = new MqttPacketFormatterAdapter(writer);
+                    var channel = new MqttWebSocketChannel(webSocket, endpoint, isSecureConnection, clientCertificate);
+
+                    using (var channelAdapter = new MqttChannelAdapter(channel, formatter, _logger.CreateChildLogger(nameof(MqttWebSocketServerAdapter))))
+                    {
+                        await clientHandler(channelAdapter).ConfigureAwait(false);
+                    }
+                }
+            }
+            finally
+            {
+                clientCertificate?.Dispose();
             }
         }
 

Source/MQTTnet.AspnetCore/ReaderExtensions.cs

@@ -9,13 +9,20 @@ namespace MQTTnet.AspNetCore
 {
     public static class ReaderExtensions
     {
-        public static bool TryDecode(this MqttPacketFormatterAdapter formatter, in ReadOnlySequence<byte> input, out MqttBasePacket packet, out SequencePosition consumed, out SequencePosition observed)
+        public static bool TryDecode(this MqttPacketFormatterAdapter formatter, 
+            SpanBasedMqttPacketBodyReader reader, 
+            in ReadOnlySequence<byte> input, 
+            out MqttBasePacket packet, 
+            out SequencePosition consumed, 
+            out SequencePosition observed,
+            out int bytesRead)
         {
             if (formatter == null) throw new ArgumentNullException(nameof(formatter));
 
             packet = null;
             consumed = input.Start;
             observed = input.End;
+            bytesRead = 0;
             var copy = input;
 
             if (copy.Length < 2)
@@ -24,7 +31,7 @@ namespace MQTTnet.AspNetCore
             }
 
             var fixedheader = copy.First.Span[0];
-            if (!TryReadBodyLength(ref copy, out var bodyLength))
+            if (!TryReadBodyLength(ref copy, out int headerLength, out var bodyLength))
             {
                 return false;
             }
@@ -35,34 +42,45 @@ namespace MQTTnet.AspNetCore
             }
 
             var bodySlice = copy.Slice(0, bodyLength);
-            var buffer = bodySlice.GetArray();
-            packet = formatter.Decode(new ReceivedMqttPacket(fixedheader, new MqttPacketBodyReader(buffer, 0, buffer.Length), buffer.Length + 2));
+            var buffer = bodySlice.GetMemory();
+            reader.SetBuffer(buffer);
+
+            var receivedMqttPacket = new ReceivedMqttPacket(fixedheader, reader, buffer.Length + 2);
+
+            if (formatter.ProtocolVersion == MqttProtocolVersion.Unknown)
+            {
+                formatter.DetectProtocolVersion(receivedMqttPacket);
+            }
+
+            packet = formatter.Decode(receivedMqttPacket);
             consumed = bodySlice.End;
             observed = bodySlice.End;
+            bytesRead = headerLength + bodyLength;
             return true;
         }
 
-        private static byte[] GetArray(this in ReadOnlySequence<byte> input)
+        private static ReadOnlyMemory<byte> GetMemory(this in ReadOnlySequence<byte> input)
         {
             if (input.IsSingleSegment)
             {
-                return input.First.Span.ToArray();
+                return input.First;
             }
 
             // Should be rare
             return input.ToArray();
         }
 
-        private static bool TryReadBodyLength(ref ReadOnlySequence<byte> input, out int result)
+        private static bool TryReadBodyLength(ref ReadOnlySequence<byte> input, out int headerLength, out int bodyLength)
         {
             // Alorithm taken from https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/errata01/os/mqtt-v3.1.1-errata01-os-complete.html.
             var multiplier = 1;
             var value = 0;
             byte encodedByte;
             var index = 1;
-            result = 0;
-
-            var temp = input.Slice(0, Math.Min(5, input.Length)).GetArray();
+            headerLength = 0;
+            bodyLength = 0;
+            
+            var temp = input.Slice(0, Math.Min(5, input.Length)).GetMemory();
 
             do
             {
@@ -70,13 +88,13 @@ namespace MQTTnet.AspNetCore
                 {
                     return false;
                 }
-                encodedByte = temp[index];
+                encodedByte = temp.Span[index];
                 index++;
 
                 value += (byte)(encodedByte & 127) * multiplier;
                 if (multiplier > 128 * 128 * 128)
                 {
-                    throw new MqttProtocolViolationException($"Remaining length is invalid (Data={string.Join(",", temp.AsSpan(1, index).ToArray())}).");
+                    throw new MqttProtocolViolationException($"Remaining length is invalid (Data={string.Join(",", temp.Slice(1, index).ToArray())}).");
                 }
 
                 multiplier *= 128;
@@ -84,7 +102,8 @@ namespace MQTTnet.AspNetCore
 
             input = input.Slice(index);
 
-            result = value;
+            headerLength = index;
+            bodyLength = value;
             return true;
         }
     }

Source/MQTTnet.AspnetCore/SpanBasedMqttPacketBodyReader.cs

@@ -0,0 +1,125 @@
+using MQTTnet.Exceptions;
+using MQTTnet.Formatter;
+using System;
+using System.Buffers.Binary;
+using System.Text;
+
+namespace MQTTnet.AspNetCore
+{
+    public class SpanBasedMqttPacketBodyReader : IMqttPacketBodyReader
+    {
+        private ReadOnlyMemory<byte> _buffer;
+
+        private int _offset;
+        
+        public void SetBuffer(ReadOnlyMemory<byte> buffer)
+        {
+            _buffer = buffer;
+            _offset = 0;
+        }
+
+        public int Length => _buffer.Length;
+
+        public bool EndOfStream => _buffer.Length.Equals(_offset);
+        
+        public int Offset => _offset;
+
+        public byte ReadByte()
+        {
+            return _buffer.Span[_offset++];
+        }
+
+        public byte[] ReadRemainingData()
+        {
+            return _buffer.Slice(_offset).ToArray();
+        }
+
+        public byte[] ReadWithLengthPrefix()
+        {
+            return ReadSegmentWithLengthPrefix().ToArray();
+        }
+
+        private ReadOnlySpan<byte> ReadSegmentWithLengthPrefix()
+        {
+            var span = _buffer.Span;
+            var length = BinaryPrimitives.ReadUInt16BigEndian(span.Slice(_offset));
+
+            var result = span.Slice(_offset+2, length);
+            _offset += 2 + length;
+            return result;
+        }
+        
+        public unsafe string ReadStringWithLengthPrefix()
+        {
+            var buffer = ReadSegmentWithLengthPrefix();
+            if (buffer.Length == 0)
+            {
+                return string.Empty;
+            }
+
+            fixed (byte* bytes = &buffer.GetPinnableReference())
+            {
+                var result = Encoding.UTF8.GetString(bytes, buffer.Length);
+                return result;
+            }
+        }
+
+        public ushort ReadTwoByteInteger()
+        {
+            var result = BinaryPrimitives.ReadUInt16BigEndian(_buffer.Span.Slice(_offset));
+            _offset += 2;
+            return result;
+        }
+
+        public uint ReadFourByteInteger()
+        {
+            var result = BinaryPrimitives.ReadUInt32BigEndian(_buffer.Span.Slice(_offset));
+            _offset += 4;
+            return result;
+        }
+
+        public uint ReadVariableLengthInteger()
+        {
+            var multiplier = 1;
+            var value = 0U;
+            byte encodedByte;
+
+            do
+            {
+                encodedByte = ReadByte();
+                value += (uint)((encodedByte & 127) * multiplier);
+
+                if (multiplier > 2097152)
+                {
+                    throw new MqttProtocolViolationException("Variable length integer is invalid.");
+                }
+
+                multiplier *= 128;
+            } while ((encodedByte & 128) != 0);
+
+            return value;
+        }
+
+        public bool ReadBoolean()
+        {
+            var buffer = ReadByte();
+
+            if (buffer == 0)
+            {
+                return false;
+            }
+
+            if (buffer == 1)
+            {
+                return true;
+            }
+
+            throw new MqttProtocolViolationException("Boolean values can be 0 or 1 only.");
+        }
+
+        public void Seek(int position)
+        {
+            _offset = position;
+        }
+    }
+}

Source/MQTTnet.AspnetCore/SpanBasedMqttPacketWriter.cs

@@ -0,0 +1,146 @@
+using MQTTnet.Formatter;
+using System;
+using System.Buffers;
+using System.Buffers.Binary;
+using System.Text;
+
+namespace MQTTnet.AspNetCore
+{
+    public class SpanBasedMqttPacketWriter : IMqttPacketWriter
+    {
+        private readonly ArrayPool<byte> _pool;
+
+        public SpanBasedMqttPacketWriter()
+        {
+            _pool = ArrayPool<byte>.Create();
+            
+        }
+
+        private byte[] _buffer;
+        private int _position;
+
+        public int Length { get; set; }
+
+        public void FreeBuffer()
+        {
+            _pool.Return(_buffer);
+        }
+
+        public byte[] GetBuffer()
+        {
+            return _buffer;
+        }
+
+        public void Reset(int v)
+        {
+            _buffer = _pool.Rent(1500);
+            Length = v;
+            _position = v;
+        }
+
+        public void Seek(int v)
+        {
+            _position = v;
+        }
+
+        public void Write(byte value)
+        {
+            GrowIfNeeded(1);
+            _buffer[_position] = value;
+            Commit(1);
+        }
+
+        public void Write(ushort value)
+        {
+            GrowIfNeeded(2);
+
+            BinaryPrimitives.WriteUInt16BigEndian(_buffer.AsSpan(_position), value);
+            Commit(2);
+        }
+
+        public void Write(IMqttPacketWriter propertyWriter)
+        {
+            if (propertyWriter == null) throw new ArgumentNullException(nameof(propertyWriter));
+
+            GrowIfNeeded(propertyWriter.Length);
+            Write(propertyWriter.GetBuffer(), 0, propertyWriter.Length);
+            Commit(propertyWriter.Length);
+        }
+
+        public void Write(byte[] payload, int start, int length)
+        {
+            GrowIfNeeded(length);
+
+            payload.AsSpan(start, length).CopyTo(_buffer.AsSpan(_position));
+            Commit(length);
+        }
+
+        public void WriteVariableLengthInteger(uint value)
+        {
+            GrowIfNeeded(4);
+            
+            var x = value;
+            do
+            {
+                var encodedByte = x % 128;
+                x = x / 128;
+                if (x > 0)
+                {
+                    encodedByte = encodedByte | 128;
+                }
+
+                _buffer[_position] = (byte)encodedByte;
+                Commit(1);
+            } while (x > 0);
+        }
+
+        public void WriteWithLengthPrefix(string value)
+        {
+            var bytesLength = Encoding.UTF8.GetByteCount(value ?? string.Empty);
+            GrowIfNeeded(bytesLength + 2);
+
+            Write((ushort)bytesLength);
+            Encoding.UTF8.GetBytes(value ?? string.Empty, 0, value?.Length ?? 0, _buffer, _position);
+            Commit(bytesLength);
+        }
+
+        public void WriteWithLengthPrefix(byte[] payload)
+        {
+            GrowIfNeeded(payload.Length + 2);
+            
+            Write((ushort)payload.Length);
+            payload.CopyTo(_buffer, _position);
+            Commit(payload.Length);
+        }
+
+        private void Commit(int count)
+        {
+            if (_position == Length)
+            {
+                Length += count;
+            }
+
+            _position += count;
+        }
+
+        private void GrowIfNeeded(int requiredAdditional) 
+        {
+            var requiredTotal = _position + requiredAdditional;
+            if (_buffer.Length >= requiredTotal)
+            {
+                return;
+            }
+
+            var newBufferLength = _buffer.Length;
+            while (newBufferLength < requiredTotal)
+            {
+                newBufferLength *= 2;
+            }
+
+            var newBuffer = _pool.Rent(newBufferLength);
+            Array.Copy(_buffer, newBuffer, _buffer.Length);
+            _pool.Return(_buffer);
+            _buffer = newBuffer;
+        }
+    }
+}

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

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <TargetFrameworks>netstandard1.3;netstandard2.0</TargetFrameworks>
     <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net452;net461</TargetFrameworks>
-    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' AND '$(MSBuildRuntimeType)' != 'Core'">$(TargetFrameworks);uap10.0</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' AND '$(MSBuildRuntimeType)' != 'Core' AND '$(SolutionName)' != 'MQTTnet.noUWP' ">$(TargetFrameworks);uap10.0</TargetFrameworks>
     <Product />
     <Company />
     <Authors />

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs

@@ -31,7 +31,7 @@ namespace MQTTnet.Extensions.ManagedClient
 
         private ManagedMqttClientStorageManager _storageManager;
 
-        private bool _disposed = false;
+        private bool _disposed;
         private bool _subscriptionsNotPushed;
 
         public ManagedMqttClient(IMqttClient mqttClient, IMqttNetChildLogger logger)
@@ -102,9 +102,8 @@ namespace MQTTnet.Extensions.ManagedClient
 
             _connectionCancellationToken = new CancellationTokenSource();
 
-#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
             _maintainConnectionTask = Task.Run(() => MaintainConnectionAsync(_connectionCancellationToken.Token), _connectionCancellationToken.Token);
-#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
+            _maintainConnectionTask.Forget(_logger);
 
             _logger.Info("Started");
         }
@@ -333,20 +332,20 @@ namespace MQTTnet.Extensions.ManagedClient
             }
         }
 
-        private void PublishQueuedMessages(CancellationToken cancellationToken)
+        private async Task PublishQueuedMessagesAsync(CancellationToken cancellationToken)
         {
             try
             {
                 while (!cancellationToken.IsCancellationRequested && _mqttClient.IsConnected)
                 {
-                    //Peek at the message without dequeueing in order to prevent the
-                    //possibility of the queue growing beyond the configured cap.
-                    //Previously, messages could be re-enqueued if there was an
-                    //exception, and this re-enqueueing did not honor the cap.
-                    //Furthermore, because re-enqueueing would shuffle the order
-                    //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.
+                    // Peek at the message without dequeueing in order to prevent the
+                    // possibility of the queue growing beyond the configured cap.
+                    // Previously, messages could be re-enqueued if there was an
+                    // exception, and this re-enqueueing did not honor the cap.
+                    // Furthermore, because re-enqueueing would shuffle the order
+                    // 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();
                     if (message == null)
                     {
@@ -355,7 +354,7 @@ namespace MQTTnet.Extensions.ManagedClient
 
                     cancellationToken.ThrowIfCancellationRequested();
 
-                    TryPublishQueuedMessage(message);
+                    await TryPublishQueuedMessageAsync(message).ConfigureAwait(false);
                 }
             }
             catch (OperationCanceledException)
@@ -371,23 +370,28 @@ namespace MQTTnet.Extensions.ManagedClient
             }
         }
 
-        private void TryPublishQueuedMessage(ManagedMqttApplicationMessage message)
+        private async Task TryPublishQueuedMessageAsync(ManagedMqttApplicationMessage message)
         {
             Exception transmitException = null;
             try
             {
-                _mqttClient.PublishAsync(message.ApplicationMessage).GetAwaiter().GetResult();
+                await _mqttClient.PublishAsync(message.ApplicationMessage).ConfigureAwait(false);
+
                 lock (_messageQueue) //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
-                    //with the DropOldestQueuedMessage strategy).  If the first item
-                    //in the queue is equal to this message, then it's safe to remove
-                    //it from the queue.  If not, that means this.PublishAsync has already
-                    //removed it, in which case we don't want to do anything.
+                    // While publishing this message, this.PublishAsync could have booted this
+                    // message off the queue to make room for another (when using a cap
+                    // with the DropOldestQueuedMessage strategy).  If the first item
+                    // in the queue is equal to this message, then it's safe to remove
+                    // 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));
                 }
-                _storageManager?.RemoveAsync(message).GetAwaiter().GetResult();
+
+                if (_storageManager != null)
+                {
+                    await _storageManager.RemoveAsync(message).ConfigureAwait(false);
+                }
             }
             catch (MqttCommunicationException exception)
             {
@@ -408,6 +412,11 @@ namespace MQTTnet.Extensions.ManagedClient
                     {
                         _messageQueue.RemoveFirst(i => i.Id.Equals(message.Id));
                     }
+
+                    if (_storageManager != null)
+                    {
+                        await _storageManager.RemoveAsync(message).ConfigureAwait(false);
+                    }
                 }
             }
             catch (Exception exception)
@@ -417,7 +426,12 @@ namespace MQTTnet.Extensions.ManagedClient
             }
             finally
             {
-                ApplicationMessageProcessedHandler?.HandleApplicationMessageProcessedAsync(new ApplicationMessageProcessedEventArgs(message, transmitException)).GetAwaiter().GetResult();
+                var eventHandler = ApplicationMessageProcessedHandler;
+                if (eventHandler != null)
+                {
+                    var eventArguments = new ApplicationMessageProcessedEventArgs(message, transmitException);
+                    await eventHandler.HandleApplicationMessageProcessedAsync(eventArguments).ConfigureAwait(false);
+                }
             }
         }
 
@@ -502,7 +516,7 @@ namespace MQTTnet.Extensions.ManagedClient
             var cts = new CancellationTokenSource();
             _publishingCancellationToken = cts;
 
-            Task.Factory.StartNew(() => PublishQueuedMessages(cts.Token), cts.Token, TaskCreationOptions.LongRunning, TaskScheduler.Default);
+            Task.Run(() => PublishQueuedMessagesAsync(cts.Token), cts.Token).Forget(_logger);
         }
 
         private void StopPublishing()

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

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <TargetFrameworks>netstandard1.3;netstandard2.0</TargetFrameworks>
     <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net452;net461</TargetFrameworks>
-    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' AND '$(MSBuildRuntimeType)' != 'Core'">$(TargetFrameworks);uap10.0</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' AND '$(MSBuildRuntimeType)' != 'Core' AND '$(SolutionName)' != 'MQTTnet.noUWP' ">$(TargetFrameworks);uap10.0</TargetFrameworks>
     <Product />
     <Company />
     <Authors />

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

@@ -0,0 +1,34 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>netstandard1.3;netstandard2.0</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net452;net461</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' AND '$(MSBuildRuntimeType)' != 'Core' AND '$(SolutionName)' != 'MQTTnet.noUWP' ">$(TargetFrameworks);uap10.0</TargetFrameworks>
+    <Product />
+    <Company />
+    <Authors />
+    <PackageId />
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0'">
+    <CopyLocalLockFileAssemblies>false</CopyLocalLockFileAssemblies>
+    <NugetTargetMoniker>UAP,Version=v10.0</NugetTargetMoniker>
+    <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
+    <TargetPlatformVersion>10.0.17134.0</TargetPlatformVersion>
+    <TargetPlatformMinVersion>10.0.10240.0</TargetPlatformMinVersion>
+    <TargetFrameworkIdentifier>.NETCore</TargetFrameworkIdentifier>
+    <TargetFrameworkVersion>v5.0</TargetFrameworkVersion>
+    <DefineConstants>$(DefineConstants);WINDOWS_UWP</DefineConstants>
+    <DefaultLanguage>en</DefaultLanguage>
+    <LanguageTargets>$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets</LanguageTargets>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="WebSocket4Net" Version="0.15.2" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\MQTTnet\MQTTnet.csproj" />
+  </ItemGroup>
+
+</Project>

Source/MQTTnet.Extensions.WebSocket4Net/MqttFactoryExtensions.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace MQTTnet.Extensions.WebSocket4Net
+{
+    public static class MqttFactoryExtensions
+    {
+        public static IMqttFactory UseWebSocket4Net(this IMqttFactory mqttFactory)
+        {
+            if (mqttFactory == null) throw new ArgumentNullException(nameof(mqttFactory));
+
+            return mqttFactory.UseClientAdapterFactory(new WebSocket4NetMqttClientAdapterFactory());
+        }
+    }
+}

Source/MQTTnet.Extensions.WebSocket4Net/WebSocket4NetMqttChannel.cs

@@ -0,0 +1,233 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Security.Authentication;
+using System.Security.Cryptography.X509Certificates;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Channel;
+using MQTTnet.Client.Options;
+using MQTTnet.Exceptions;
+using MQTTnet.Internal;
+using SuperSocket.ClientEngine;
+using WebSocket4Net;
+
+namespace MQTTnet.Extensions.WebSocket4Net
+{
+    public class WebSocket4NetMqttChannel : IMqttChannel
+    {
+        private readonly BlockingCollection<byte> _receiveBuffer = new BlockingCollection<byte>();
+
+        private readonly IMqttClientOptions _clientOptions;
+        private readonly MqttClientWebSocketOptions _webSocketOptions;
+
+        private WebSocket _webSocket;
+
+        public WebSocket4NetMqttChannel(IMqttClientOptions clientOptions, MqttClientWebSocketOptions webSocketOptions)
+        {
+            _clientOptions = clientOptions ?? throw new ArgumentNullException(nameof(clientOptions));
+            _webSocketOptions = webSocketOptions ?? throw new ArgumentNullException(nameof(webSocketOptions));
+        }
+
+        public string Endpoint => _webSocketOptions.Uri;
+
+        public bool IsSecureConnection { get; private set; }
+
+        public X509Certificate2 ClientCertificate { get; }
+
+        public async Task ConnectAsync(CancellationToken cancellationToken)
+        {
+            var uri = _webSocketOptions.Uri;
+            if (!uri.StartsWith("ws://", StringComparison.OrdinalIgnoreCase) && !uri.StartsWith("wss://", StringComparison.OrdinalIgnoreCase))
+            {
+                if (_webSocketOptions.TlsOptions?.UseTls == false)
+                {
+                    uri = "ws://" + uri;
+                }
+                else
+                {
+                    uri = "wss://" + uri;
+                }
+            }
+
+            var sslProtocols = _webSocketOptions?.TlsOptions?.SslProtocol ?? SslProtocols.None;
+            var subProtocol = _webSocketOptions.SubProtocols.FirstOrDefault() ?? string.Empty;
+
+            var cookies = new List<KeyValuePair<string, string>>();
+            if (_webSocketOptions.CookieContainer != null)
+            {
+                throw new NotSupportedException("Cookies are not supported.");
+            }
+
+            List<KeyValuePair<string, string>> customHeaders = null;
+            if (_webSocketOptions.RequestHeaders != null)
+            {
+                customHeaders = _webSocketOptions.RequestHeaders.Select(i => new KeyValuePair<string, string>(i.Key, i.Value)).ToList();
+            }
+
+            EndPoint proxy = null;
+            if (_webSocketOptions.ProxyOptions != null)
+            {
+                throw new NotSupportedException("Proxies are not supported.");
+            }
+
+            // The user agent can be empty always because it is just added to the custom headers as "User-Agent".
+            var userAgent = string.Empty;
+
+            var origin = string.Empty;
+            var webSocketVersion = WebSocketVersion.None;
+            var receiveBufferSize = 0;
+
+            var certificates = new X509CertificateCollection();
+            if (_webSocketOptions?.TlsOptions?.Certificates != null)
+            {
+                foreach (var certificate in _webSocketOptions.TlsOptions.Certificates)
+                {
+                    certificates.Add(new X509Certificate(certificate));
+                }
+            }
+
+            _webSocket = new WebSocket(uri, subProtocol, cookies, customHeaders, userAgent, origin, webSocketVersion, proxy, sslProtocols, receiveBufferSize)
+            {
+                NoDelay = true,
+                Security =
+                {
+                    AllowUnstrustedCertificate = _webSocketOptions?.TlsOptions?.AllowUntrustedCertificates == true,
+                    AllowCertificateChainErrors = _webSocketOptions?.TlsOptions?.IgnoreCertificateChainErrors == true,
+                    Certificates = certificates
+                }
+            };
+
+            await ConnectInternalAsync(cancellationToken).ConfigureAwait(false);
+            
+            IsSecureConnection = uri.StartsWith("wss://", StringComparison.OrdinalIgnoreCase);
+        }
+
+        public Task DisconnectAsync(CancellationToken cancellationToken)
+        {
+            if (_webSocket != null && _webSocket.State == WebSocketState.Open)
+            {
+                _webSocket.Close();
+            }
+            
+            return Task.FromResult(0);
+        }
+
+        public Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            var readBytes = 0;
+            while (count > 0 && !cancellationToken.IsCancellationRequested)
+            {
+                if (!_receiveBuffer.TryTake(out var @byte))
+                {
+                    if (readBytes == 0)
+                    {
+                        // Block until at least one byte was received.
+                        @byte = _receiveBuffer.Take(cancellationToken);
+                    }
+                    else
+                    {
+                        return Task.FromResult(readBytes);
+                    }
+                }
+
+                buffer[offset] = @byte;
+                offset++;
+                count--;
+                readBytes++;
+            }
+
+            return Task.FromResult(readBytes);
+        }
+
+        public Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            _webSocket.Send(buffer, offset, count);
+            return Task.FromResult(0);
+        }
+
+        public void Dispose()
+        {
+            if (_webSocket == null)
+            {
+                return;
+            }
+
+            _webSocket.DataReceived -= OnDataReceived;
+            _webSocket.Error -= OnError;
+            _webSocket.Dispose();
+            _webSocket = null;
+        }
+
+        private void OnError(object sender, ErrorEventArgs e)
+        {
+            System.Diagnostics.Debug.Write(e.Exception.ToString());
+        }
+
+        private void OnDataReceived(object sender, DataReceivedEventArgs e)
+        {
+            foreach (var @byte in e.Data)
+            {
+                _receiveBuffer.Add(@byte);
+            }
+        }
+
+        private async Task ConnectInternalAsync(CancellationToken cancellationToken)
+        {
+            _webSocket.Error += OnError;
+            _webSocket.DataReceived += OnDataReceived;
+
+            var taskCompletionSource = new TaskCompletionSource<Exception>();
+
+            void ErrorHandler(object sender, ErrorEventArgs e)
+            {
+                taskCompletionSource.TrySetResult(e.Exception);
+            }
+
+            void SuccessHandler(object sender, EventArgs e)
+            {
+                taskCompletionSource.TrySetResult(null);
+            }
+
+            try
+            {
+                _webSocket.Opened += SuccessHandler;
+                _webSocket.Error += ErrorHandler;
+
+                _webSocket.Open();
+
+                var exception = await MqttTaskTimeout.WaitAsync(c =>
+                {
+                    c.Register(() => taskCompletionSource.TrySetCanceled());
+                    return taskCompletionSource.Task;
+                }, _clientOptions.CommunicationTimeout, cancellationToken).ConfigureAwait(false);
+
+                if (exception != null)
+                {
+                    if (exception is AuthenticationException authenticationException)
+                    {
+                        throw new MqttCommunicationException(authenticationException.InnerException);
+                    }
+
+                    if (exception is OperationCanceledException)
+                    {
+                        throw new MqttCommunicationTimedOutException();
+                    }
+
+                    throw new MqttCommunicationException(exception);
+                }
+            }
+            catch (OperationCanceledException)
+            {
+                throw new MqttCommunicationTimedOutException();
+            }
+            finally
+            {
+                _webSocket.Opened -= SuccessHandler;
+                _webSocket.Error -= ErrorHandler;
+            }
+        }
+    }
+}

Source/MQTTnet.Extensions.WebSocket4Net/WebSocket4NetMqttClientAdapterFactory.cs

@@ -0,0 +1,36 @@
+using System;
+using MQTTnet.Adapter;
+using MQTTnet.Client.Options;
+using MQTTnet.Diagnostics;
+using MQTTnet.Formatter;
+using MQTTnet.Implementations;
+
+namespace MQTTnet.Extensions.WebSocket4Net
+{
+    public class WebSocket4NetMqttClientAdapterFactory : IMqttClientAdapterFactory
+    {
+        public IMqttChannelAdapter CreateClientAdapter(IMqttClientOptions options, IMqttNetChildLogger logger)
+        {
+            if (options == null) throw new ArgumentNullException(nameof(options));
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
+            switch (options.ChannelOptions)
+            {
+                case MqttClientTcpOptions _:
+                {
+                    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);
+                }
+
+                default:
+                {
+                    throw new NotSupportedException();
+                }
+            }
+        }
+    }
+}

Source/MQTTnet.Server/Configuration/MqttSettingsModel.cs

@@ -1,9 +1,9 @@
 namespace MQTTnet.Server.Configuration
 {
     /// <summary>
-    /// Main Settings Model
+    /// MQTT settings Model
     /// </summary>
-    public class SettingsModel
+    public class MqttSettingsModel
     {
         /// <summary>
         /// Set default connection timeout in seconds
@@ -45,6 +45,9 @@
         /// </summary>
         public RetainedApplicationMessagesModel RetainedApplicationMessages { get; set; } = new RetainedApplicationMessagesModel();
 
+        /// <summary>
+        /// Enables or disables the MQTTnet internal logging.
+        /// </summary>
         public bool EnableDebugLogging { get; set; } = false;
     }
 }

Source/MQTTnet.Server/Configuration/PathHelper.cs

@@ -0,0 +1,24 @@
+using System;
+using System.IO;
+
+namespace MQTTnet.Server.Configuration
+{
+    public static class PathHelper
+    {
+        public static string ExpandPath(string path)
+        {
+            if (path == null)
+            {
+                return null;
+            }
+
+            var uri = new Uri(path, UriKind.RelativeOrAbsolute);
+            if (!uri.IsAbsoluteUri)
+            {
+                return Path.Combine(AppDomain.CurrentDomain.BaseDirectory, path);
+            }
+
+            return path;
+        }
+    }
+}

Source/MQTTnet.Server/Configuration/RetainedApplicationMessagesModel.cs

@@ -6,6 +6,6 @@
 
         public int WriteInterval { get; set; } = 10;
 
-        public string Filename { get; set; } = "RetainedApplicationMessages.json";
+        public string Path { get; set; }
     }
 }

Source/MQTTnet.Server/Configuration/ScriptingSettingsModel.cs

@@ -0,0 +1,11 @@
+using System.Collections.Generic;
+
+namespace MQTTnet.Server.Configuration
+{
+    public class ScriptingSettingsModel
+    {
+        public string ScriptsPath { get; set; }
+
+        public List<string> IncludePaths { get; set; }
+    }
+}

Source/MQTTnet.Server/Configuration/TcpEndpointModel.cs

@@ -60,13 +60,13 @@ namespace MQTTnet.Server.Configuration
         {
             if (IPv4 == "*")
             {
-                address = IPAddress.Parse("0.0.0.0");
+                address = IPAddress.Any;
                 return true;
             }
 
             if (IPv4 == "localhost")
             {
-                address = IPAddress.Parse("127.0.0.1");
+                address = IPAddress.Loopback;
                 return true;
             }
 
@@ -81,10 +81,8 @@ namespace MQTTnet.Server.Configuration
                 address = ip;
                 return true;
             }
-            else
-            {
-                throw new System.Exception($"Could not parse IPv4 address: {IPv4}");
-            }
+
+            throw new System.Exception($"Could not parse IPv4 address: {IPv4}");
         }
 
         /// <summary>
@@ -95,13 +93,13 @@ namespace MQTTnet.Server.Configuration
         {
             if (IPv6 == "*")
             {
-                address = IPAddress.Parse("::");
+                address = IPAddress.IPv6Any;
                 return true;
             }
 
             if (IPv6 == "localhost")
             {
-                address = IPAddress.Parse("::1");
+                address = IPAddress.IPv6Loopback;
                 return true;
             }
 
@@ -116,10 +114,8 @@ namespace MQTTnet.Server.Configuration
                 address = ip;
                 return true;
             }
-            else
-            {
-                throw new System.Exception($"Could not parse IPv6 address: {IPv6}");
-            }
+
+            throw new System.Exception($"Could not parse IPv6 address: {IPv6}");
         }
     }
 }

Source/MQTTnet.Server/Controllers/ClientsController.cs

@@ -0,0 +1,79 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Threading.Tasks;
+using System.Web;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using MQTTnet.Server.Mqtt;
+using MQTTnet.Server.Status;
+
+namespace MQTTnet.Server.Controllers
+{
+    [Authorize]
+    [ApiController]
+    public class ClientsController : ControllerBase
+    {
+        private readonly MqttServerService _mqttServerService;
+
+        public ClientsController(MqttServerService mqttServerService)
+        {
+            _mqttServerService = mqttServerService ?? throw new ArgumentNullException(nameof(mqttServerService));
+        }
+
+        [Route("api/v1/clients")]
+        [HttpGet]
+        public async Task<ActionResult<IList<IMqttClientStatus>>> GetClients()
+        {
+            return new ObjectResult(await _mqttServerService.GetClientStatusAsync());
+        }
+
+        [Route("api/v1/clients/{clientId}")]
+        [HttpGet]
+        public async Task<ActionResult<IMqttClientStatus>> GetClient(string clientId)
+        {
+            clientId = HttpUtility.UrlDecode(clientId);
+
+            var client = (await _mqttServerService.GetClientStatusAsync()).FirstOrDefault(c => c.ClientId == clientId);
+            if (client == null)
+            {
+                return new StatusCodeResult((int)HttpStatusCode.NotFound);
+            }
+
+            return new ObjectResult(client);
+        }
+
+        [Route("api/v1/clients/{clientId}")]
+        [HttpDelete]
+        public async Task<ActionResult> DeleteClient(string clientId)
+        {
+            clientId = HttpUtility.UrlDecode(clientId);
+
+            var client = (await _mqttServerService.GetClientStatusAsync()).FirstOrDefault(c => c.ClientId == clientId);
+            if (client == null)
+            {
+                return new StatusCodeResult((int)HttpStatusCode.NotFound);
+            }
+
+            await client.DisconnectAsync();
+            return StatusCode((int)HttpStatusCode.NoContent);
+        }
+
+        [Route("api/v1/clients/{clientId}/statistics")]
+        [HttpDelete]
+        public async Task<ActionResult> DeleteClientStatistics(string clientId)
+        {
+            clientId = HttpUtility.UrlDecode(clientId);
+
+            var client = (await _mqttServerService.GetClientStatusAsync()).FirstOrDefault(c => c.ClientId == clientId);
+            if (client == null)
+            {
+                return new StatusCodeResult((int)HttpStatusCode.NotFound);
+            }
+
+            client.ResetStatistics();
+            return StatusCode((int)HttpStatusCode.NoContent);
+        }
+    }
+}

Source/MQTTnet.Server/Controllers/RetainedApplicationMessagesController.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Threading.Tasks;
+using System.Web;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using MQTTnet.Server.Mqtt;
+
+namespace MQTTnet.Server.Controllers
+{
+    [Authorize]
+    [ApiController]
+    public class RetainedApplicationMessagesController : ControllerBase
+    {
+        private readonly MqttServerService _mqttServerService;
+
+        public RetainedApplicationMessagesController(MqttServerService mqttServerService)
+        {
+            _mqttServerService = mqttServerService ?? throw new ArgumentNullException(nameof(mqttServerService));
+        }
+
+        [Route("api/v1/retainedApplicationMessages")]
+        [HttpGet]
+        public async Task<ActionResult<IList<MqttApplicationMessage>>> GetRetainedApplicationMessages()
+        {
+            return new ObjectResult(await _mqttServerService.GetRetainedApplicationMessagesAsync());
+        }
+
+        [Route("api/v1/retainedApplicationMessages/{topic}")]
+        [HttpGet]
+        public async Task<ActionResult<MqttApplicationMessage>> GetRetainedApplicationMessage(string topic)
+        {
+            topic = HttpUtility.UrlDecode(topic);
+
+            var applicationMessage = (await _mqttServerService.GetRetainedApplicationMessagesAsync()).FirstOrDefault(c => c.Topic == topic);
+            if (applicationMessage == null)
+            {
+                return new StatusCodeResult((int)HttpStatusCode.NotFound);
+            }
+
+            return new ObjectResult(applicationMessage);
+        }
+
+        [Route("api/v1/retainedApplicationMessages")]
+        [HttpDelete]
+        public async Task<ActionResult> DeleteRetainedApplicationMessages()
+        {
+            await _mqttServerService.ClearRetainedApplicationMessagesAsync();
+            return StatusCode((int)HttpStatusCode.NoContent);
+        }
+
+        [Route("api/v1/retainedApplicationMessages/{topic}")]
+        [HttpDelete]
+        public async Task<ActionResult> DeleteRetainedApplicationMessage(string topic)
+        {
+            topic = HttpUtility.UrlDecode(topic);
+
+            await _mqttServerService.PublishAsync(new MqttApplicationMessageBuilder().WithTopic(topic).WithRetainFlag().Build());
+            return StatusCode((int)HttpStatusCode.NoContent);
+        }
+    }
+}

Source/MQTTnet.Server/Controllers/ScriptsController.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using MQTTnet.Server.Scripting;
+using MQTTnet.Server.Web;
+
+namespace MQTTnet.Server.Controllers
+{
+    [Authorize]
+    [ApiController]
+    public class ScriptsController : Controller
+    {
+        private readonly PythonScriptHostService _pythonScriptHostService;
+
+        public ScriptsController(PythonScriptHostService pythonScriptHostService)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+        }
+
+        [Route("api/v1/scripts")]
+        [HttpGet]
+        public ActionResult<List<string>> GetScriptUids()
+        {
+            return _pythonScriptHostService.GetScriptUids();
+        }
+
+        [Route("api/v1/scripts/uid")]
+        [HttpGet]
+        public async Task<ActionResult<string>> GetScript(string uid)
+        {
+            var script = await _pythonScriptHostService.ReadScriptAsync(uid, HttpContext.RequestAborted);
+            if (script == null)
+            {
+                return NotFound();
+            }
+
+            return Content(script);
+        }
+
+        [Route("api/v1/scripts/uid")]
+        [HttpPost]
+        public Task PostScript(string uid)
+        {
+            var code = HttpContext.Request.ReadBodyAsString();
+            return _pythonScriptHostService.WriteScriptAsync(uid, code, CancellationToken.None);
+        }
+
+        [Route("api/v1/scripts/uid")]
+        [HttpDelete]
+        public Task DeleteScript(string uid)
+        {
+            return _pythonScriptHostService.DeleteScriptAsync(uid);
+        }
+        
+        [Route("api/v1/scripts/initialize")]
+        [HttpPost]
+        public Task PostInitializeScripts()
+        {
+            return _pythonScriptHostService.TryInitializeScriptsAsync();
+        }
+    }
+}

Source/MQTTnet.Server/Controllers/SessionsController.cs

@@ -0,0 +1,79 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Threading.Tasks;
+using System.Web;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using MQTTnet.Server.Mqtt;
+using MQTTnet.Server.Status;
+
+namespace MQTTnet.Server.Controllers
+{
+    [Authorize]
+    [ApiController]
+    public class SessionsController : ControllerBase
+    {
+        private readonly MqttServerService _mqttServerService;
+
+        public SessionsController(MqttServerService mqttServerService)
+        {
+            _mqttServerService = mqttServerService ?? throw new ArgumentNullException(nameof(mqttServerService));
+        }
+
+        [Route("api/v1/sessions")]
+        [HttpGet]
+        public async Task<ActionResult<IList<IMqttSessionStatus>>> GetSessions()
+        {
+            return new ObjectResult(await _mqttServerService.GetSessionStatusAsync());
+        }
+
+        [Route("api/v1/sessions/{clientId}")]
+        [HttpGet]
+        public async Task<ActionResult<IMqttClientStatus>> GetSession(string clientId)
+        {
+            clientId = HttpUtility.UrlDecode(clientId);
+
+            var session = (await _mqttServerService.GetSessionStatusAsync()).FirstOrDefault(c => c.ClientId == clientId);
+            if (session == null)
+            {
+                return new StatusCodeResult((int)HttpStatusCode.NotFound);
+            }
+
+            return new ObjectResult(session);
+        }
+
+        [Route("api/v1/sessions/{clientId}")]
+        [HttpDelete]
+        public async Task<ActionResult> DeleteSession(string clientId)
+        {
+            clientId = HttpUtility.UrlDecode(clientId);
+
+            var session = (await _mqttServerService.GetSessionStatusAsync()).FirstOrDefault(c => c.ClientId == clientId);
+            if (session == null)
+            {
+                return new StatusCodeResult((int)HttpStatusCode.NotFound);
+            }
+
+            await session.DeleteAsync();
+            return StatusCode((int)HttpStatusCode.NoContent);
+        }
+
+        [Route("api/v1/sessions/{clientId}/pendingApplicationMessages")]
+        [HttpDelete]
+        public async Task<ActionResult> DeletePendingApplicationMessages(string clientId)
+        {
+            clientId = HttpUtility.UrlDecode(clientId);
+
+            var session = (await _mqttServerService.GetSessionStatusAsync()).FirstOrDefault(c => c.ClientId == clientId);
+            if (session == null)
+            {
+                return new StatusCodeResult((int)HttpStatusCode.NotFound);
+            }
+
+            await session.ClearPendingApplicationMessagesAsync();
+            return StatusCode((int)HttpStatusCode.NoContent);
+        }
+    }
+}

Source/MQTTnet.Server/Controllers/ValuesController.cs

@@ -1,42 +0,0 @@
-using System.Collections.Generic;
-using Microsoft.AspNetCore.Mvc;
-
-namespace MQTTnet.Server.Controllers
-{
-    [Route("api/[controller]")]
-    [ApiController]
-    public class ValuesController : ControllerBase
-    {
-        // GET api/values
-        [HttpGet]
-        public ActionResult<IEnumerable<string>> Get()
-        {
-            return new string[] { "value1", "value2" };
-        }
-
-        // GET api/values/5
-        [HttpGet("{id}")]
-        public ActionResult<string> Get(int id)
-        {
-            return "value";
-        }
-
-        // POST api/values
-        [HttpPost]
-        public void Post([FromBody] string value)
-        {
-        }
-
-        // PUT api/values/5
-        [HttpPut("{id}")]
-        public void Put(int id, [FromBody] string value)
-        {
-        }
-
-        // DELETE api/values/5
-        [HttpDelete("{id}")]
-        public void Delete(int id)
-        {
-        }
-    }
-}

Source/MQTTnet.Server/LICENSE

@@ -1,6 +1,7 @@
+# MQTTnet
 MIT License
 
-Copyright (c) 2017 Christian Kratky
+Copyright (c) 2019 MQTTnet Team
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -19,3 +20,78 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
+
+# Swashbuckle
+Copyright (c) 2013, Richard Morris
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE
+
+# IronPython
+Copyright (c) .NET Foundation and Contributors
+           All Rights Reserved
+
+Apache License
+Version 2.0, January 2004
+http://www.apache.org/licenses/ 
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 
+
+1. Definitions.
+
+"License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. 
+
+"Licensor" shall mean the copyright owner or entity authorized by the copyright owner that is granting the License. 
+
+"Legal Entity" shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, "control" means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity. 
+
+"You" (or "Your") shall mean an individual or Legal Entity exercising permissions granted by this License. 
+
+"Source" form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files. 
+
+"Object" form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types. 
+
+"Work" shall mean the work of authorship, whether in Source or Object form, made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below). 
+
+"Derivative Works" shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship. For the purposes of this License, Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof. 
+
+"Contribution" shall mean any work of authorship, including the original version of the Work and any modifications or additions to that Work or Derivative Works thereof, that is intentionally submitted to Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose of discussing and improving the Work, but excluding communication that is conspicuously marked or otherwise designated in writing by the copyright owner as "Not a Contribution." 
+
+"Contributor" shall mean Licensor and any individual or Legal Entity on behalf of whom a Contribution has been received by Licensor and subsequently incorporated within the Work. 
+
+2. Grant of Copyright License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form. 
+
+3. Grant of Patent License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by combination of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed. 
+
+4. Redistribution. You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions: 
+
+You must give any other recipients of the Work or Derivative Works a copy of this License; and 
+
+
+You must cause any modified files to carry prominent notices stating that You changed the files; and 
+
+
+You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and 
+
+
+If the Work includes a "NOTICE" text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices contained within such NOTICE file, excluding those notices that do not pertain to any part of the Derivative Works, in at least one of the following places: within a NOTICE text file distributed as part of the Derivative Works; within the Source form or documentation, if provided along with the Derivative Works; or, within a display generated by the Derivative Works, if and wherever such third-party notices normally appear. The contents of the NOTICE file are for informational purposes only and do not modify the License. You may add Your own attribution notices within Derivative Works that You distribute, alongside or as an addendum to the NOTICE text from the Work, provided that such additional attribution notices cannot be construed as modifying the License. 
+You may add Your own copyright statement to Your modifications and may provide additional or different license terms and conditions for use, reproduction, or distribution of Your modifications, or for any such Derivative Works as a whole, provided Your use, reproduction, and distribution of the Work otherwise complies with the conditions stated in this License. 
+
+5. Submission of Contributions. Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions. 
+
+6. Trademarks. This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor, except as required for reasonable and customary use in describing the origin of the Work and reproducing the content of the NOTICE file. 
+
+7. Disclaimer of Warranty. Unless required by applicable law or agreed to in writing, Licensor provides the Work (and each Contributor provides its Contributions) on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or redistributing the Work and assume any risks associated with Your exercise of permissions under this License. 
+
+8. Limitation of Liability. In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages. 
+
+9. Accepting Warranty or Additional Liability. While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may act only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability. 
+

Source/MQTTnet.Server/Logging/MqttNetLoggerWrapper.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading;
 using Microsoft.Extensions.Logging;
 using MQTTnet.Diagnostics;
 
@@ -14,7 +15,7 @@ namespace MQTTnet.Server.Logging
         }
 
         public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
-        
+
         public IMqttNetChildLogger CreateChildLogger(string source = null)
         {
             return new MqttNetChildLoggerWrapper(source, this);
@@ -24,8 +25,15 @@ namespace MQTTnet.Server.Logging
         {
             var convertedLogLevel = ConvertLogLevel(logLevel);
             _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);
+                logMessagePublishedEvent.Invoke(this, new MqttNetLogMessagePublishedEventArgs(logMessage));
+            }
+        }
+        
         private static LogLevel ConvertLogLevel(MqttNetLogLevel logLevel)
         {
             switch (logLevel)

Source/MQTTnet.Server/MQTTnet.Server.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <TargetFramework>netcoreapp2.2</TargetFramework>
@@ -14,11 +14,13 @@
     <SignAssembly>false</SignAssembly>
     <DelaySign>false</DelaySign>
     <LangVersion>latest</LangVersion>
+    <Version>1.0.0</Version>
     <TypeScriptToolsVersion>3.3</TypeScriptToolsVersion>
   </PropertyGroup>
 
   <PropertyGroup>
     <StartupObject></StartupObject>
+    <UserSecretsId>c564f0de-28b4-45bf-b726-4d665d705653</UserSecretsId>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
@@ -27,6 +29,13 @@
     <NoWarn>1701;1702</NoWarn>
   </PropertyGroup>
 
+  <ItemGroup>
+    <Compile Remove="wwwroot\**" />
+    <Content Remove="wwwroot\**" />
+    <EmbeddedResource Remove="wwwroot\**" />
+    <None Remove="wwwroot\**" />
+  </ItemGroup>
+
   <ItemGroup>
     <Content Update="appsettings.json">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
@@ -40,8 +49,8 @@
     <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="4.0.1" />
-    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="4.0.1" />
+    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerGen" Version="5.0.0-rc2" />
+    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="5.0.0-rc2" />
   </ItemGroup>
 
   <ItemGroup>
@@ -53,22 +62,23 @@
     <None Update="LICENSE">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
-    <None Update="run.sh">
+    <None Update="README.md">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
-    <None Update="run.bat">
-      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
-    </None>
-    <None Update="Scripts\readme.md">
+    <None Update="Scripts\README.md">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
     <None Update="Scripts\00_sample.py">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
+    <None Update="Web\authorization_handler.py">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
   </ItemGroup>
 
   <ItemGroup>
-    <Folder Include="wwwroot\" />
+    <Folder Include="Properties\PublishProfiles\" />
+    <Folder Include="Web\wwwroot\" />
   </ItemGroup>
 
 </Project>

Source/MQTTnet.Server/Mqtt/CustomMqttFactory.cs

@@ -12,7 +12,7 @@ namespace MQTTnet.Server.Mqtt
     {
         private readonly MqttFactory _mqttFactory;
 
-        public CustomMqttFactory(SettingsModel settings, ILogger<MqttServer> logger)
+        public CustomMqttFactory(MqttSettingsModel settings, ILogger<MqttServer> logger)
         {
             if (settings == null) throw new ArgumentNullException(nameof(settings));
             if (logger == null) throw new ArgumentNullException(nameof(logger));

Source/MQTTnet.Server/Mqtt/MqttApplicationMessageInterceptor.cs

@@ -46,21 +46,5 @@ namespace MQTTnet.Server.Mqtt
 
             return Task.CompletedTask;
         }
-
-        // TODO: Create dump(object) method in wrapper (creates JSON and prints it).
-        public class PythonMqttApplicationMessageInterceptorContext
-        {
-            public bool accept_connection;
-
-            public bool accept_publish;
-
-            public string client_id;
-
-            public string topic;
-
-            public int qos;
-
-            public bool retain;
-        }
     }
 }

Source/MQTTnet.Server/Mqtt/MqttServerConnectionValidator.cs

@@ -7,12 +7,12 @@ using MQTTnet.Server.Scripting;
 
 namespace MQTTnet.Server.Mqtt
 {
-    public class MqttConnectionValidator : IMqttServerConnectionValidator
+    public class MqttServerConnectionValidator : IMqttServerConnectionValidator
     {
         private readonly PythonScriptHostService _pythonScriptHostService;
         private readonly ILogger _logger;
 
-        public MqttConnectionValidator(PythonScriptHostService pythonScriptHostService, ILogger<MqttConnectionValidator> logger)
+        public MqttServerConnectionValidator(PythonScriptHostService pythonScriptHostService, ILogger<MqttServerConnectionValidator> logger)
         {
             _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
@@ -24,21 +24,28 @@ namespace MQTTnet.Server.Mqtt
             {
                 var pythonContext = new PythonDictionary
                 {
-                    { "client_id", context.ClientId },
                     { "endpoint", context.Endpoint },
                     { "is_secure_connection", context.IsSecureConnection },
+                    { "client_id", context.ClientId },
                     { "username", context.Username },
                     { "password", context.Password },
-                    { "result", PythonConvert.Pythonfy(context.ReturnCode) }
+                    { "raw_password", new Bytes(context.RawPassword ?? new byte[0]) },
+                    { "clean_session", context.CleanSession},
+                    { "authentication_method", context.AuthenticationMethod},
+                    { "authentication_data", new Bytes(context.AuthenticationData ?? new byte[0]) },
+
+                    { "result", PythonConvert.Pythonfy(context.ReasonCode) }
                 };
 
                 _pythonScriptHostService.InvokeOptionalFunction("on_validate_client_connection", pythonContext);
 
-                context.ReturnCode = PythonConvert.ParseEnum<MqttConnectReturnCode>((string)pythonContext["result"]);
+                context.ReasonCode = PythonConvert.ParseEnum<MqttConnectReasonCode>((string)pythonContext["result"]);
             }
             catch (Exception exception)
             {
                 _logger.LogError(exception, "Error while validating client connection.");
+
+                context.ReasonCode = MqttConnectReasonCode.UnspecifiedError;
             }
 
             return Task.CompletedTask;

Source/MQTTnet.Server/Mqtt/MqttServerService.cs

@@ -10,10 +10,12 @@ using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Logging;
 using MQTTnet.Adapter;
 using MQTTnet.AspNetCore;
+using MQTTnet.Client.Publishing;
 using MQTTnet.Implementations;
 using MQTTnet.Protocol;
 using MQTTnet.Server.Configuration;
 using MQTTnet.Server.Scripting;
+using MQTTnet.Server.Status;
 
 namespace MQTTnet.Server.Mqtt
 {
@@ -21,34 +23,34 @@ namespace MQTTnet.Server.Mqtt
     {
         private readonly ILogger<MqttServerService> _logger;
 
-        private readonly SettingsModel _settings;
+        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 MqttConnectionValidator _mqttConnectionValidator;
+        private readonly MqttServerConnectionValidator _mqttConnectionValidator;
         private readonly IMqttServer _mqttServer;
         private readonly MqttSubscriptionInterceptor _mqttSubscriptionInterceptor;
         private readonly PythonScriptHostService _pythonScriptHostService;
         private readonly MqttWebSocketServerAdapter _webSocketServerAdapter;
 
         public MqttServerService(
-            SettingsModel settings,
+            MqttSettingsModel mqttSettings,
             CustomMqttFactory mqttFactory,
             MqttClientConnectedHandler mqttClientConnectedHandler,
             MqttClientDisconnectedHandler mqttClientDisconnectedHandler,
             MqttClientSubscribedTopicHandler mqttClientSubscribedTopicHandler,
             MqttClientUnsubscribedTopicHandler mqttClientUnsubscribedTopicHandler,
-            MqttConnectionValidator mqttConnectionValidator,
+            MqttServerConnectionValidator mqttConnectionValidator,
             MqttSubscriptionInterceptor mqttSubscriptionInterceptor,
             MqttApplicationMessageInterceptor mqttApplicationMessageInterceptor,
             MqttServerStorage mqttServerStorage,
             PythonScriptHostService pythonScriptHostService,            
             ILogger<MqttServerService> logger)
         {
-            _settings = settings ?? throw new ArgumentNullException(nameof(settings));
+            _settings = mqttSettings ?? throw new ArgumentNullException(nameof(mqttSettings));
             _mqttClientConnectedHandler = mqttClientConnectedHandler ?? throw new ArgumentNullException(nameof(mqttClientConnectedHandler));
             _mqttClientDisconnectedHandler = mqttClientDisconnectedHandler ?? throw new ArgumentNullException(nameof(mqttClientDisconnectedHandler));
             _mqttClientSubscribedTopicHandler = mqttClientSubscribedTopicHandler ?? throw new ArgumentNullException(nameof(mqttClientSubscribedTopicHandler));
@@ -64,7 +66,10 @@ namespace MQTTnet.Server.Mqtt
 
             var adapters = new List<IMqttServerAdapter>
             {
-                new MqttTcpServerAdapter(mqttFactory.Logger.CreateChildLogger()),
+                new MqttTcpServerAdapter(mqttFactory.Logger.CreateChildLogger())
+                {
+                    TreatSocketOpeningErrorAsWarning = true // Opening other ports than for HTTP is not allows in Azure App Services.
+                },
                 _webSocketServerAdapter
             };
 
@@ -92,6 +97,33 @@ namespace MQTTnet.Server.Mqtt
             return _webSocketServerAdapter.RunWebSocketConnectionAsync(webSocket, httpContext);
         }
 
+        public Task<IList<IMqttClientStatus>> GetClientStatusAsync()
+        {
+            return _mqttServer.GetClientStatusAsync();
+        }
+
+        public Task<IList<IMqttSessionStatus>> GetSessionStatusAsync()
+        {
+            return _mqttServer.GetSessionStatusAsync();
+        }
+
+        public Task ClearRetainedApplicationMessagesAsync()
+        {
+            return _mqttServer.ClearRetainedApplicationMessagesAsync();
+        }
+
+        public Task<IList<MqttApplicationMessage>> GetRetainedApplicationMessagesAsync()
+        {
+            return _mqttServer.GetRetainedApplicationMessagesAsync();
+        }
+
+        public Task<MqttClientPublishResult> PublishAsync(MqttApplicationMessage applicationMessage)
+        {
+            if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
+
+            return _mqttServer.PublishAsync(applicationMessage);
+        }
+
         private void Publish(PythonDictionary parameters)
         {
             try
@@ -152,6 +184,7 @@ namespace MQTTnet.Server.Mqtt
             if (_settings.TcpEndPoint.Enabled)
             {
                 options.WithDefaultEndpoint();
+
                 if (_settings.TcpEndPoint.TryReadIPv4(out var address4))
                 {
                     options.WithDefaultEndpointBoundIPAddress(address4);

Source/MQTTnet.Server/Mqtt/MqttServerStorage.cs

@@ -14,27 +14,28 @@ namespace MQTTnet.Server.Mqtt
     {
         private readonly List<MqttApplicationMessage> _messages = new List<MqttApplicationMessage>();
 
-        private readonly SettingsModel _settings;
+        private readonly MqttSettingsModel _mqttSettings;
         private readonly ILogger<MqttServerStorage> _logger;
 
-        private string _filename;
+        private string _path;
         private bool _messagesHaveChanged;
 
-        public MqttServerStorage(SettingsModel settings, ILogger<MqttServerStorage> logger)
+        public MqttServerStorage(MqttSettingsModel mqttSettings, ILogger<MqttServerStorage> logger)
         {
-            _settings = settings ?? throw new ArgumentNullException(nameof(settings));
+            _mqttSettings = mqttSettings ?? throw new ArgumentNullException(nameof(mqttSettings));
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
         }
 
         public void Configure()
         {
-            if (_settings.RetainedApplicationMessages?.Persist != true)
+            if (_mqttSettings.RetainedApplicationMessages?.Persist != true || 
+                string.IsNullOrEmpty(_mqttSettings.RetainedApplicationMessages.Path))
             {
                 _logger.LogInformation("Persisting of retained application messages is disabled.");
                 return;
             }
 
-            _filename = ExpandFilename();
+            _path = PathHelper.ExpandPath(_mqttSettings.RetainedApplicationMessages.Path);
 
             // The retained application messages are stored in a separate thread.
             // This is mandatory because writing them to a slow storage (like RaspberryPi SD card) 
@@ -61,7 +62,7 @@ namespace MQTTnet.Server.Mqtt
             {
                 try
                 {
-                    await Task.Delay(TimeSpan.FromSeconds(_settings.RetainedApplicationMessages.WriteInterval)).ConfigureAwait(false);
+                    await Task.Delay(TimeSpan.FromSeconds(_mqttSettings.RetainedApplicationMessages.WriteInterval)).ConfigureAwait(false);
 
                     List<MqttApplicationMessage> messages;
                     lock (_messages)
@@ -76,7 +77,7 @@ namespace MQTTnet.Server.Mqtt
                     }
 
                     var json = JsonConvert.SerializeObject(messages);
-                    await File.WriteAllTextAsync(_filename, json, Encoding.UTF8).ConfigureAwait(false);
+                    await File.WriteAllTextAsync(_path, json, Encoding.UTF8).ConfigureAwait(false);
                     
                     _logger.LogInformation($"{messages.Count} retained MQTT messages written.");
                 }
@@ -89,19 +90,19 @@ namespace MQTTnet.Server.Mqtt
 
         public async Task<IList<MqttApplicationMessage>> LoadRetainedMessagesAsync()
         {
-            if (_settings.RetainedApplicationMessages?.Persist != true)
+            if (_mqttSettings.RetainedApplicationMessages?.Persist != true)
             {
                 return null;
             }
 
-            if (!File.Exists(_filename))
+            if (!File.Exists(_path))
             {
                 return null;
             }
 
             try
             {
-                var json = await File.ReadAllTextAsync(_filename).ConfigureAwait(false);
+                var json = await File.ReadAllTextAsync(_path).ConfigureAwait(false);
                 var applicationMessages = JsonConvert.DeserializeObject<List<MqttApplicationMessage>>(json);
 
                 _logger.LogInformation($"{applicationMessages.Count} retained MQTT messages loaded.");
@@ -114,18 +115,5 @@ namespace MQTTnet.Server.Mqtt
                 return null;
             }
         }
-
-        private string ExpandFilename()
-        {
-            var filename = _settings.RetainedApplicationMessages.Filename;
-
-            var uri = new Uri(filename, UriKind.RelativeOrAbsolute);
-            if (!uri.IsAbsoluteUri)
-            {
-                filename = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, filename);
-            }
-
-            return filename;
-        }
     }
 }

Source/MQTTnet.Server/Program.cs

@@ -1,6 +1,8 @@
 using System;
+using System.Reflection;
 using Microsoft.AspNetCore;
 using Microsoft.AspNetCore.Hosting;
+using MQTTnet.Server.Web;
 
 namespace MQTTnet.Server
 {
@@ -12,7 +14,8 @@ namespace MQTTnet.Server
             {
                 PrintLogo();
 
-                CreateWebHostBuilder(args).Build().Run();
+                WebHost.CreateDefaultBuilder(args).UseStartup<Startup>().Build().Run();
+
                 return 0;
             }
             catch (Exception exception)
@@ -22,46 +25,43 @@ namespace MQTTnet.Server
             }
         }
 
-        private static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
-            WebHost.CreateDefaultBuilder(args)
-                  .UseKestrel()
-                  .UseStartup<Startup>();
-
         private static void PrintLogo()
         {
             Console.ResetColor();
             Console.ForegroundColor = ConsoleColor.Red;
-            Console.WriteLine(@"
-  __  __  ____ _______ _______         _      _____
- |  \/  |/ __ \__   __|__   __|       | |    / ____|
- | \  / | |  | | | |     | |_ __   ___| |_  | (___   ___ _ ____   _____ _ __
- | |\/| | |  | | | |     | | '_ \ / _ \ __|  \___ \ / _ \ '__\ \ / / _ \ '__|
- | |  | | |__| | | |     | | | | |  __/ |_   ____) |  __/ |   \ V /  __/ |
- |_|  |_|\___\_\ |_|     |_|_| |_|\___|\__| |_____/ \___|_|    \_/ \___|_|");
+            const string LogoText =
+@"
+
+███╗   ███╗ ██████╗ ████████╗████████╗███╗   ██╗███████╗████████╗    ███████╗███████╗██████╗ ██╗   ██╗███████╗██████╗ 
+████╗ ████║██╔═══██╗╚══██╔══╝╚══██╔══╝████╗  ██║██╔════╝╚══██╔══╝    ██╔════╝██╔════╝██╔══██╗██║   ██║██╔════╝██╔══██╗
+██╔████╔██║██║   ██║   ██║      ██║   ██╔██╗ ██║█████╗     ██║       ███████╗█████╗  ██████╔╝██║   ██║█████╗  ██████╔╝
+██║╚██╔╝██║██║▄▄ ██║   ██║      ██║   ██║╚██╗██║██╔══╝     ██║       ╚════██║██╔══╝  ██╔══██╗╚██╗ ██╔╝██╔══╝  ██╔══██╗
+██║ ╚═╝ ██║╚██████╔╝   ██║      ██║   ██║ ╚████║███████╗   ██║       ███████║███████╗██║  ██║ ╚████╔╝ ███████╗██║  ██║
+╚═╝     ╚═╝ ╚══▀▀═╝    ╚═╝      ╚═╝   ╚═╝  ╚═══╝╚══════╝   ╚═╝       ╚══════╝╚══════╝╚═╝  ╚═╝  ╚═══╝  ╚══════╝╚═╝  ╚═╝
+                                                                                                                      
+";
+
+            Console.WriteLine(LogoText);
+            Console.ResetColor();
+            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.WriteLine(@"https://github.com/chkr1011/MQTTnet");
 
             Console.ForegroundColor = ConsoleColor.White;
-            Console.WriteLine(@"
-          -- The official MQTT server implementation of MQTTnet --
-                 Copyright (c) 2017-2019 The MQTTnet Team");
-
-            Console.ForegroundColor = ConsoleColor.Blue;
-            Console.WriteLine(@"
-                   https://github.com/chkr1011/MQTTnet");
-
-            Console.ForegroundColor = ConsoleColor.White;
-            Console.WriteLine(@"
- Version:    1.0.0-alpha2
- License:    MIT (read LICENSE file)
- Sponsoring: https://opencollective.com/mqttnet
- Support:    https://github.com/chkr1011/MQTTnet/issues
- Docs:       https://github.com/chkr1011/MQTTnet/wiki/MQTTnetServer
+            Console.WriteLine($@"
+Version:    {Assembly.GetExecutingAssembly().GetCustomAttribute<AssemblyInformationalVersionAttribute>().InformationalVersion}
+License:    MIT (read LICENSE file)
+Sponsoring: https://opencollective.com/mqttnet
+Support:    https://github.com/chkr1011/MQTTnet/issues
+Docs:       https://github.com/chkr1011/MQTTnet/wiki/MQTTnetServer
 ");
 
-            Console.BackgroundColor = ConsoleColor.White;
             Console.ForegroundColor = ConsoleColor.Red;
             Console.WriteLine(" ! THIS IS AN ALPHA VERSION! IT IS NOT RECOMMENDED TO USE IT FOR ANY DIFFERENT PURPOSE THAN TESTING OR EVALUATING!");
-            Console.WriteLine();
             Console.ResetColor();
+            Console.WriteLine();
         }
     }
 }

Source/MQTTnet.Server/README.md

@@ -0,0 +1,10 @@
+# Starting portable version
+The portable version requires a local installation of the .net core runtime. With that runtime installed the server can be started via the following comand.
+
+dotnet .\MQTTnet.Server.dll
+
+# Starting self contained versions
+The self contained versions are fully portable versions including the .net core runtime. The server can be started using the contained executable files.
+
+Windows:    MQTTnet.Server.exe
+Linux:		MQTTnet.Server (must be set to _executable_ first)

Source/MQTTnet.Server/RetainedApplicationMessages.json

@@ -1 +0,0 @@
-[{"Topic":"a","Payload":"YWFzYXNhc2E=","QualityOfServiceLevel":0,"Retain":true,"UserProperties":[],"ContentType":null,"ResponseTopic":null,"PayloadFormatIndicator":null,"MessageExpiryInterval":null,"TopicAlias":null,"CorrelationData":null,"SubscriptionIdentifier":null},{"Topic":"fgdfgd","Payload":"YWFzYXNhc2E=","QualityOfServiceLevel":0,"Retain":true,"UserProperties":[],"ContentType":null,"ResponseTopic":null,"PayloadFormatIndicator":null,"MessageExpiryInterval":null,"TopicAlias":null,"CorrelationData":null,"SubscriptionIdentifier":null}]

Source/MQTTnet.Server/Scripting/PythonScriptHostService.cs

@@ -4,9 +4,12 @@ using System.Dynamic;
 using System.IO;
 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
 {
@@ -14,26 +17,27 @@ namespace MQTTnet.Server.Scripting
     {
         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;
         
-        public PythonScriptHostService(PythonIOStream pythonIOStream, ILogger<PythonScriptHostService> logger)
+        public PythonScriptHostService(ScriptingSettingsModel scriptingSettings, PythonIOStream pythonIOStream, ILogger<PythonScriptHostService> logger)
         {
+            _scriptingSettings = scriptingSettings ?? throw new ArgumentNullException(nameof(scriptingSettings));
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
 
             _scriptEngine = IronPython.Hosting.Python.CreateEngine();
             _scriptEngine.Runtime.IO.SetOutput(pythonIOStream, Encoding.UTF8);
+
+            _scriptsPath = PathHelper.ExpandPath(scriptingSettings.ScriptsPath);
         }
 
         public void Configure()
         {
             AddSearchPaths(_scriptEngine);
 
-            var scriptsDirectory = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Scripts");
-            foreach (var filename in Directory.GetFiles(scriptsDirectory, "*.py", SearchOption.AllDirectories).OrderBy(file => file))
-            {
-                TryInitializeScript(filename);
-            }
+            TryInitializeScriptsAsync().GetAwaiter().GetResult();
         }
 
         public void RegisterProxyObject(string name, object @object)
@@ -58,35 +62,109 @@ namespace MQTTnet.Server.Scripting
                     }
                     catch (Exception exception)
                     {
-                        _logger.LogError(exception, $"Error while invoking function '{name}' at script '{pythonScriptInstance.Name}'.");
+                        _logger.LogError(exception, $"Error while invoking function '{name}' at script '{pythonScriptInstance.Uid}'.");
                     }
                 }
             }
         }
 
-        private void TryInitializeScript(string filename)
+        public List<string> GetScriptUids()
         {
-            try
+            lock (_scriptInstances)
             {
-                var scriptName = new FileInfo(filename).Name;
-
-                _logger.LogTrace($"Initializing Python script '{scriptName}'...");
-                var code = File.ReadAllText(filename);
-
-                var scriptInstance = CreateScriptInstance(scriptName, code);
-                scriptInstance.InvokeOptionalFunction("initialize");
-
-                _scriptInstances.Add(scriptInstance);
-
-                _logger.LogInformation($"Initialized script '{scriptName}'.");
-            }
-            catch (Exception exception)
-            {
-                _logger.LogError(exception, $"Error while initializing script '{new FileInfo(filename).Name}'.");
+                return _scriptInstances.Select(si => si.Uid).ToList();
             }
         }
 
-        private PythonScriptInstance CreateScriptInstance(string name, string code)
+        public Task<string> ReadScriptAsync(string uid, CancellationToken cancellationToken)
+        {
+            if (uid == null) throw new ArgumentNullException(nameof(uid));
+
+            string path;
+
+            lock (_scriptInstances)
+            {
+                path = _scriptInstances.FirstOrDefault(si => si.Uid == uid)?.Path;
+            }
+
+            if (path == null || !File.Exists(path))
+            {
+                return null;
+            }
+
+            return File.ReadAllTextAsync(path, Encoding.UTF8, cancellationToken);
+        }
+
+        public async Task WriteScriptAsync(string uid, string code, CancellationToken cancellationToken)
+        {
+            var path = Path.Combine(_scriptsPath, uid + ".py");
+
+            await File.WriteAllTextAsync(path, code, Encoding.UTF8, cancellationToken).ConfigureAwait(false);
+            await TryInitializeScriptsAsync().ConfigureAwait(false);
+        }
+
+        public async Task DeleteScriptAsync(string uid)
+        {
+            var path = Path.Combine(_scriptsPath, uid + ".py");
+
+            if (File.Exists(path))
+            {
+                File.Delete(path);
+                await TryInitializeScriptsAsync().ConfigureAwait(false);
+            }
+        }
+
+        public async Task TryInitializeScriptsAsync()
+        {
+            lock (_scriptInstances)
+            {
+                foreach (var scriptInstance in _scriptInstances)
+                {
+                    try
+                    {
+                        scriptInstance.InvokeOptionalFunction("destroy");
+                    }
+                    catch (Exception exception)
+                    {
+                        _logger.LogWarning(exception, $"Error while unloading script '{scriptInstance.Uid}'.");
+                    }
+                }
+
+                _scriptInstances.Clear();
+            }
+
+            foreach (var path in Directory.GetFiles(_scriptsPath, "*.py", SearchOption.AllDirectories).OrderBy(file => file))
+            {
+                await TryInitializeScriptAsync(path).ConfigureAwait(false);
+            }
+        }
+
+        private async Task TryInitializeScriptAsync(string path)
+        {
+            var uid = new FileInfo(path).Name.Replace(".py", string.Empty, StringComparison.OrdinalIgnoreCase);
+
+            try
+            {
+                _logger.LogTrace($"Initializing Python script '{uid}'...");
+                var code = await File.ReadAllTextAsync(path).ConfigureAwait(false);
+
+                var scriptInstance = CreateScriptInstance(uid, path, code);
+                scriptInstance.InvokeOptionalFunction("initialize");
+
+                lock (_scriptInstances)
+                {
+                    _scriptInstances.Add(scriptInstance);
+                }
+                
+                _logger.LogInformation($"Initialized script '{uid}'.");
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, $"Error while initializing script '{uid}'.");
+            }
+        }
+
+        private PythonScriptInstance CreateScriptInstance(string uid, string path, string code)
         {
             var scriptScope = _scriptEngine.CreateScope();
 
@@ -96,31 +174,26 @@ namespace MQTTnet.Server.Scripting
             scriptScope.SetVariable("mqtt_net_server", _proxyObjects);
             compiledCode.Execute(scriptScope);
             
-            return new PythonScriptInstance(name, scriptScope);
+            return new PythonScriptInstance(uid, path, scriptScope);
         }
 
         private void AddSearchPaths(ScriptEngine scriptEngine)
         {
-            var paths = new List<string>
+            if (_scriptingSettings.IncludePaths?.Any() != true)
             {
-                Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Lib"),
-                "/usr/lib/python2.7",
-                @"C:\Python27\Lib"
-            };
-            
-            AddSearchPaths(scriptEngine, paths);
-        }
+                return;
+            }
 
-        private void AddSearchPaths(ScriptEngine scriptEngine, IEnumerable<string> paths)
-        {
             var searchPaths = scriptEngine.GetSearchPaths();
 
-            foreach (var path in paths)
+            foreach (var path in _scriptingSettings.IncludePaths)
             {
-                if (Directory.Exists(path))
+                var effectivePath = PathHelper.ExpandPath(path);
+
+                if (Directory.Exists(effectivePath))
                 {
-                    searchPaths.Add(path);
-                    _logger.LogInformation($"Added Python lib path: {path}");
+                    searchPaths.Add(effectivePath);
+                    _logger.LogInformation($"Added Python lib path: {effectivePath}");
                 }
             }
 

Source/MQTTnet.Server/Scripting/PythonScriptInstance.cs

@@ -8,14 +8,17 @@ namespace MQTTnet.Server.Scripting
     {
         private readonly ScriptScope _scriptScope;
 
-        public PythonScriptInstance(string name, ScriptScope scriptScope)
+        public PythonScriptInstance(string uid, string path, ScriptScope scriptScope)
         {
-            _scriptScope = scriptScope;
+            Uid = uid;
+            Path = path;
 
-            Name = name;
+            _scriptScope = scriptScope;
         }
 
-        public string Name { get; }
+        public string Uid { get; }
+
+        public string Path { get; }
 
         public bool InvokeOptionalFunction(string name, params object[] parameters)
         {

Source/MQTTnet.Server/Scripts/00_sample.py

@@ -7,9 +7,17 @@ def initialize():
     It will be executed only one time.
     """
 
-    print("Hello World from Sample script.")
+    print("Hello World from sample script.")
    
 
+def destroy():
+    """
+    This function is invoked when the script is unloaded due to a script file update etc.
+    """
+
+    print("Bye from sample script.")
+
+    
 def on_validate_client_connection(context):
     """
     This function is invoked whenever a client wants to connect. It can be used to validate the connection.
@@ -17,20 +25,45 @@ def on_validate_client_connection(context):
     
     print(context)
 
+    # Access some custom data here which was inserted upon connect and may use it for validation.
     mqtt_net_server.write_shared_data(context["client_id"], {"custom_value_1": 1, "custom_value_2": True})
 
     return
+    
+    # Supported results:
+    # * success
+    # * unspecified_error
+    # * malformed_packet
+    # * protocol_error
+    # * implementation_specific_error
+    # * unsupported_protocol_version
+    # * client_identifier_not_valid
+    # * bad_user_name_or_password
+    # * not_authorized
+    # * server_unavailable
+    # * server_busy
+    # * banned
+    # * bad_authentication_method
+    # * topic_name_invalid
+    # * packet_too_large
+    # * quota_exceeded
+    # * payload_format_invalid
+    # * retain_not_supported
+    # * qos_not_supported
+    # * use_another_server
+    # * server_moved
+    # * connection_rate_exceeded
 
     if context["client_id"] != "test_client":
-        context["result"] = "connection_refused_not_authorized"
+        context["result"] = "bad_user_name_or_password"
         return
 
     if context["username"] != "bud spencer":
-        context["result"] = "connection_refused_not_authorized"
+        context["result"] = "bad_user_name_or_password"
         return
 
-    if context["password"] != "secret":
-        context["result"] = "connection_refused_not_authorized"
+    if context["password_string"] != "secret":
+        context["result"] = "bad_user_name_or_password"
 
     print(context)
 

Source/MQTTnet.Server/Scripts/readme.md

@@ -1,9 +1,11 @@
-This directory contains scripts which are loaded by the server and can be used to perform the following tasks.
+# MQTT Scripts
 
-1. Validation of client connections via credentials, client IDs etc.
-2. Manipulation of every processed message.
-3. Validation of subscription attempts.
-4. Publishing of custom application messages.
+This directory contains scripts which are loaded by the server and can be used to perform the following tasks.
+
+* Validation of client connections via credentials, client IDs etc.
+* Manipulation of every processed message.
+* Validation of subscription attempts.
+* Publishing of custom application messages.
 
 All scripts are loaded and _MQTTnet Server_ will invoke functions according to predefined naming conventions.
 If a function is implemented in multiple scripts the context will be moved throug all instances. This allows overriding of results or passing data to other (following) scripts.

Source/MQTTnet.Server/Startup.cs

@@ -1,142 +0,0 @@
-using System;
-using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Hosting;
-using Microsoft.AspNetCore.Mvc;
-using Microsoft.EntityFrameworkCore.Internal;
-using Microsoft.Extensions.Configuration;
-using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Scripting.Utils;
-using MQTTnet.Server.Configuration;
-using MQTTnet.Server.Logging;
-using MQTTnet.Server.Mqtt;
-using MQTTnet.Server.Scripting;
-using MQTTnet.Server.Scripting.DataSharing;
-
-namespace MQTTnet.Server
-{
-    public class Startup
-    {
-        public Startup(IConfiguration configuration)
-        {
-            var builder = new ConfigurationBuilder()
-                .AddJsonFile("appsettings.json")
-                .AddEnvironmentVariables();
-
-            Configuration = builder.Build();
-        }
-
-        public IConfigurationRoot Configuration { get; }
-
-        public void Configure(
-            IApplicationBuilder application,
-            IHostingEnvironment environment,
-            MqttServerService mqttServerService,
-            PythonScriptHostService pythonScriptHostService,
-            DataSharingService dataSharingService,
-            SettingsModel settings)
-        {
-            if (environment.IsDevelopment())
-            {
-                application.UseDeveloperExceptionPage();
-            }
-            else
-            {
-                application.UseHsts();
-            }
-
-            application.UseStaticFiles();
-
-            application.UseHttpsRedirection();
-            application.UseMvc();
-
-            ConfigureWebSocketEndpoint(application, mqttServerService, settings);
-
-            dataSharingService.Configure();
-            pythonScriptHostService.Configure();
-
-            mqttServerService.Configure();
-        }
-
-        public void ConfigureServices(IServiceCollection services)
-        {
-            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
-
-            services.AddSingleton(ReadSettings());
-
-            services.AddSingleton<PythonIOStream>();
-            services.AddSingleton<PythonScriptHostService>();
-            services.AddSingleton<DataSharingService>();
-
-            services.AddSingleton<MqttNetLoggerWrapper>();
-            services.AddSingleton<CustomMqttFactory>();
-            services.AddSingleton<MqttServerService>();
-            services.AddSingleton<MqttServerStorage>();
-
-            services.AddSingleton<MqttClientConnectedHandler>();
-            services.AddSingleton<MqttClientDisconnectedHandler>();
-            services.AddSingleton<MqttClientSubscribedTopicHandler>();
-            services.AddSingleton<MqttClientUnsubscribedTopicHandler>();
-            services.AddSingleton<MqttConnectionValidator>();
-            services.AddSingleton<MqttSubscriptionInterceptor>();
-            services.AddSingleton<MqttApplicationMessageInterceptor>();
-        }
-
-        private SettingsModel ReadSettings()
-        {
-            var settings = new Configuration.SettingsModel();
-            Configuration.Bind("MQTT", settings);
-            return settings;
-        }
-
-        private static void ConfigureWebSocketEndpoint(
-            IApplicationBuilder application,
-            MqttServerService mqttServerService,
-            SettingsModel settings)
-        {
-            if (settings?.WebSocketEndPoint?.Enabled != true)
-            {
-                return;
-            }
-
-            if (string.IsNullOrEmpty(settings.WebSocketEndPoint.Path))
-            {
-                return;
-            }
-
-            var webSocketOptions = new WebSocketOptions
-            {
-                KeepAliveInterval = TimeSpan.FromSeconds(settings.WebSocketEndPoint.KeepAliveInterval),
-                ReceiveBufferSize = settings.WebSocketEndPoint.ReceiveBufferSize
-            };
-
-            if (settings.WebSocketEndPoint.AllowedOrigins?.Any() == true)
-            {
-                webSocketOptions.AllowedOrigins.AddRange(settings.WebSocketEndPoint.AllowedOrigins);
-            }
-            
-            application.UseWebSockets(webSocketOptions);
-
-            application.Use(async (context, next) =>
-            {
-                if (context.Request.Path == settings.WebSocketEndPoint.Path)
-                {
-                    if (context.WebSockets.IsWebSocketRequest)
-                    {
-                        using (var webSocket = await context.WebSockets.AcceptWebSocketAsync().ConfigureAwait(false))
-                        {
-                            await mqttServerService.RunWebSocketConnectionAsync(webSocket, context).ConfigureAwait(false);
-                        }
-                    }
-                    else
-                    {
-                        context.Response.StatusCode = 400;
-                    }
-                }
-                else
-                {
-                    await next().ConfigureAwait(false);
-                }
-            });
-        }
-    }
-}

Source/MQTTnet.Server/Web/BasicAuthenticationHandler.cs

@@ -0,0 +1,118 @@
+using System;
+using System.IO;
+using System.Net.Http.Headers;
+using System.Security.Claims;
+using System.Text;
+using System.Text.Encodings.Web;
+using System.Threading.Tasks;
+using IronPython.Runtime;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using Microsoft.Net.Http.Headers;
+using Microsoft.Scripting;
+
+namespace MQTTnet.Server.Web
+{
+    public class AuthenticationHandler : AuthenticationHandler<AuthenticationSchemeOptions>
+    {
+        private readonly ILogger<AuthenticationHandler> _logger;
+
+        public AuthenticationHandler(
+            IOptionsMonitor<AuthenticationSchemeOptions> options,
+            ILoggerFactory loggerFactory,
+            UrlEncoder encoder,
+            ISystemClock clock,
+            ILogger<AuthenticationHandler> logger)
+            : base(options, loggerFactory, encoder, clock)
+        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        protected override async Task<AuthenticateResult> HandleAuthenticateAsync()
+        {
+            if (!Request.Headers.ContainsKey(HeaderNames.Authorization))
+            {
+                return AuthenticateResult.NoResult();
+            }
+
+            try
+            {
+                var headerValue = Request.Headers[HeaderNames.Authorization];
+                var parsedHeaderValue = AuthenticationHeaderValue.Parse(Request.Headers[HeaderNames.Authorization]);
+
+                var scheme = parsedHeaderValue.Scheme;
+                var parameter = parsedHeaderValue.Parameter;
+                string username = null;
+                string password = null;
+
+                if (scheme.Equals("Basic", StringComparison.OrdinalIgnoreCase))
+                {
+                    var credentialBytes = Convert.FromBase64String(parsedHeaderValue.Parameter);
+                    var credentials = Encoding.UTF8.GetString(credentialBytes).Split(':');
+                    username = credentials[0];
+                    password = credentials[1];
+                }
+
+                var context = new PythonDictionary
+                {
+                    ["header_value"] = headerValue,
+                    ["scheme"] = scheme,
+                    ["parameter"] = parameter,
+                    ["username"] = username,
+                    ["password"] = password,
+                    ["is_authenticated"] = false
+                };
+
+                if (!ValidateUser(context))
+                {
+                    return AuthenticateResult.Fail("Invalid credentials.");
+                }
+
+                var claims = new[]
+                {
+                    new Claim(ClaimTypes.NameIdentifier, context.get("username") as string ?? string.Empty)
+                };
+
+                var identity = new ClaimsIdentity(claims, Scheme.Name);
+                var principal = new ClaimsPrincipal(identity);
+                var ticket = new AuthenticationTicket(principal, Scheme.Name);
+
+                return AuthenticateResult.Success(ticket);
+            }
+            catch (Exception exception)
+            {
+                _logger.LogWarning("Error while authenticating user.", exception);
+
+                return AuthenticateResult.Fail(exception);
+            }
+            finally
+            {
+                await Task.CompletedTask;
+            }
+        }
+
+        private bool ValidateUser(PythonDictionary context)
+        {
+            var handlerPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Web", "authorization_handler.py");
+            if (!File.Exists(handlerPath))
+            {
+                return false;
+            }
+
+            var code = File.ReadAllText(handlerPath);
+
+            var scriptEngine = IronPython.Hosting.Python.CreateEngine();
+            //scriptEngine.Runtime.IO.SetOutput(new PythonIOStream(_logger.), Encoding.UTF8);
+
+            var scriptScope = scriptEngine.CreateScope();
+            var scriptSource = scriptScope.Engine.CreateScriptSourceFromString(code, SourceCodeKind.File);
+            var compiledCode = scriptSource.Compile();
+            compiledCode.Execute(scriptScope);
+            var function = scriptScope.Engine.Operations.GetMember<PythonFunction>(scriptScope, "handle_authenticate");
+            scriptScope.Engine.Operations.Invoke(function, context);
+
+            return context.get("is_authenticated", false) as bool? == true;
+        }
+    }
+}

Source/MQTTnet.Server/Web/Extensions.cs

@@ -0,0 +1,20 @@
+using System;
+using System.IO;
+using System.Text;
+using Microsoft.AspNetCore.Http;
+
+namespace MQTTnet.Server.Web
+{
+    public static class Extensions
+    {
+        public static string ReadBodyAsString(this HttpRequest request)
+        {
+            if (request == null) throw new ArgumentNullException(nameof(request));
+
+            using (var reader = new StreamReader(request.Body, Encoding.UTF8))
+            {
+                return reader.ReadToEnd();
+            }
+        }
+    }
+}

Source/MQTTnet.Server/Web/Startup.cs

@@ -0,0 +1,221 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Net.Http.Headers;
+using Microsoft.OpenApi.Models;
+using Microsoft.Scripting.Utils;
+using MQTTnet.Server.Configuration;
+using MQTTnet.Server.Logging;
+using MQTTnet.Server.Mqtt;
+using MQTTnet.Server.Scripting;
+using MQTTnet.Server.Scripting.DataSharing;
+using Swashbuckle.AspNetCore.SwaggerUI;
+
+namespace MQTTnet.Server.Web
+{
+    public class Startup
+    {
+        public Startup(IConfiguration configuration)
+        {
+            var builder = new ConfigurationBuilder()
+                .AddJsonFile("appsettings.json")
+                .AddEnvironmentVariables();
+
+            Configuration = builder.Build();
+        }
+
+        public IConfigurationRoot Configuration { get; }
+
+        public void Configure(
+            IApplicationBuilder application,
+            IHostingEnvironment environment,
+            MqttServerService mqttServerService,
+            PythonScriptHostService pythonScriptHostService,
+            DataSharingService dataSharingService,
+            MqttSettingsModel mqttSettings)
+        {
+            if (environment.IsDevelopment())
+            {
+                application.UseDeveloperExceptionPage();
+            }
+            else
+            {
+                application.UseHsts();
+            }
+
+            application.UseCors(x => x
+                .AllowAnyOrigin()
+                .AllowAnyMethod()
+                .AllowAnyHeader()
+                .AllowCredentials());
+
+            application.UseAuthentication();
+
+            application.UseStaticFiles();
+
+            application.UseHttpsRedirection();
+            application.UseMvc();
+
+            ConfigureWebSocketEndpoint(application, mqttServerService, mqttSettings);
+
+            dataSharingService.Configure();
+            pythonScriptHostService.Configure();
+
+            mqttServerService.Configure();
+
+            application.UseSwagger(o => o.RouteTemplate = "/api/{documentName}/swagger.json");
+
+            application.UseSwaggerUI(o =>
+            {
+                o.RoutePrefix = "api";
+                o.DocumentTitle = "MQTTnet.Server API";
+                o.SwaggerEndpoint("/api/v1/swagger.json", "MQTTnet.Server API v1");
+                o.DisplayRequestDuration();
+                o.DocExpansion(DocExpansion.List);
+                o.DefaultModelRendering(ModelRendering.Model);
+            });
+        }
+
+        public void ConfigureServices(IServiceCollection services)
+        {
+            services.AddCors();
+
+            services.AddMvc()
+                .SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
+                .AddJsonOptions(options =>
+                {
+                    options.SerializerSettings.Converters.Add(new Newtonsoft.Json.Converters.StringEnumConverter());
+                });
+
+            ReadMqttSettings(services);
+
+            services.AddSingleton<PythonIOStream>();
+            services.AddSingleton<PythonScriptHostService>();
+            services.AddSingleton<DataSharingService>();
+
+            services.AddSingleton<MqttNetLoggerWrapper>();
+            services.AddSingleton<CustomMqttFactory>();
+            services.AddSingleton<MqttServerService>();
+            services.AddSingleton<MqttServerStorage>();
+
+            services.AddSingleton<MqttClientConnectedHandler>();
+            services.AddSingleton<MqttClientDisconnectedHandler>();
+            services.AddSingleton<MqttClientSubscribedTopicHandler>();
+            services.AddSingleton<MqttClientUnsubscribedTopicHandler>();
+            services.AddSingleton<MqttServerConnectionValidator>();
+            services.AddSingleton<MqttSubscriptionInterceptor>();
+            services.AddSingleton<MqttApplicationMessageInterceptor>();
+
+            services.AddSwaggerGen(c =>
+            {
+                c.DescribeAllEnumsAsStrings();
+                
+                var securityScheme = new OpenApiSecurityScheme
+                {
+                    Scheme = "Basic",
+                    Name = HeaderNames.Authorization,
+                    Type = SecuritySchemeType.Http,
+                    In = ParameterLocation.Header
+                };
+
+                c.AddSecurityDefinition("Swagger", securityScheme);
+
+                c.AddSecurityRequirement(new OpenApiSecurityRequirement
+                {
+                    [securityScheme] = new List<string>()
+                });
+
+                c.SwaggerDoc("v1", new OpenApiInfo
+                {
+                    Title = "MQTTnet.Server API",
+                    Version = "v1",
+                    Description = "The public API for the MQTT broker MQTTnet.Server.",
+                    License = new OpenApiLicense
+                    {
+                        Name = "MIT",
+                        Url = new Uri("https://github.com/chkr1011/MQTTnet/blob/master/README.md")
+                    },
+                    Contact = new OpenApiContact
+                    {
+                        Name = "MQTTnet.Server",
+                        Email = string.Empty,
+                        Url = new Uri("https://github.com/chkr1011/MQTTnet")
+                    },
+                });
+            });
+
+            services.AddAuthentication("Basic")
+                .AddScheme<AuthenticationSchemeOptions, AuthenticationHandler>("Basic", null)
+                .AddCookie();
+        }
+
+        private void ReadMqttSettings(IServiceCollection services)
+        {
+            var mqttSettings = new MqttSettingsModel();
+            Configuration.Bind("MQTT", mqttSettings);
+            services.AddSingleton(mqttSettings);
+
+            var scriptingSettings = new ScriptingSettingsModel();
+            Configuration.Bind("Scripting", scriptingSettings);
+            services.AddSingleton(scriptingSettings);
+        }
+
+        private static void ConfigureWebSocketEndpoint(
+            IApplicationBuilder application,
+            MqttServerService mqttServerService,
+            MqttSettingsModel mqttSettings)
+        {
+            if (mqttSettings?.WebSocketEndPoint?.Enabled != true)
+            {
+                return;
+            }
+
+            if (string.IsNullOrEmpty(mqttSettings.WebSocketEndPoint.Path))
+            {
+                return;
+            }
+
+            var webSocketOptions = new WebSocketOptions
+            {
+                KeepAliveInterval = TimeSpan.FromSeconds(mqttSettings.WebSocketEndPoint.KeepAliveInterval),
+                ReceiveBufferSize = mqttSettings.WebSocketEndPoint.ReceiveBufferSize
+            };
+
+            if (mqttSettings.WebSocketEndPoint.AllowedOrigins?.Any() == true)
+            {
+                webSocketOptions.AllowedOrigins.AddRange(mqttSettings.WebSocketEndPoint.AllowedOrigins);
+            }
+
+            application.UseWebSockets(webSocketOptions);
+
+            application.Use(async (context, next) =>
+            {
+                if (context.Request.Path == mqttSettings.WebSocketEndPoint.Path)
+                {
+                    if (context.WebSockets.IsWebSocketRequest)
+                    {
+                        using (var webSocket = await context.WebSockets.AcceptWebSocketAsync().ConfigureAwait(false))
+                        {
+                            await mqttServerService.RunWebSocketConnectionAsync(webSocket, context).ConfigureAwait(false);
+                        }
+                    }
+                    else
+                    {
+                        context.Response.StatusCode = (int)HttpStatusCode.BadRequest;
+                    }
+                }
+                else
+                {
+                    await next().ConfigureAwait(false);
+                }
+            });
+        }
+    }
+}

Source/MQTTnet.Server/Web/authorization_handler.py

@@ -0,0 +1,20 @@
+def handle_authenticate(context):
+    """
+    This function is invoked whenever a user tries to access protected HTTP resources.
+    This function must exist and return a proper value. Otherwise the request is denied.
+    All authentication data must be sent via using the "Authorization" header. This header
+    will be parsed and all values will be exposed to the context. 
+    """
+    header_value = context["header_value"] # The untouched header value.
+
+    scheme = context["scheme"]
+    parameter = context["parameter"]
+
+    username = context["username"] # Only set if proper "Basic" authorization is used.
+    password = context["password"] # Only set if proper "Basic" authorization is used.
+    
+    context["is_authenticated"] = True # Change this to _False_ in case of invalid credentials.
+
+    # Example for an API key with proper format.
+    if header_value == "APIKey 123456":
+        context["is_authenticated"] = True

Source/MQTTnet.Server/appsettings.json

@@ -2,10 +2,10 @@
     "Kestrel": {
         "EndPoints": {
             "Http": {
-                "Url": "http://localhost:80"
+                "Url": "http://*:80"
             },
             "Https": {
-                "Url": "http://localhost:443"
+                "Url": "http://*:443"
             }
         }
     },
@@ -18,14 +18,14 @@
         */
         "TcpEndPoint": {
             "Enabled": true,
-            "IPv4": "localhost",
-            "IPv6": "localhost",
+            "IPv4": "*",
+            "IPv6": "*",
             "Port": 1883
         },
         "EncryptedTcpEndPoint": {
             "Enabled": false,
-            "IPv4": "localhost",
-            "IPv6": "localhost",
+            "IPv4": "*",
+            "IPv6": "*",
             "Port": 8883,
             "CertificatePath": "/absolute/path/to/pfx"
         },
@@ -37,16 +37,24 @@
             "AllowedOrigins": [] // List of strings with URLs.
         },
         "CommunicationTimeout": 15, // In seconds.
-        "ConnectionBacklog": 0, /* Set 0 to disable */
-        "EnablePersistentSessions": false,
+        "ConnectionBacklog": 10, // Set 0 to disable
+        "EnablePersistentSessions": true,
         "MaxPendingMessagesPerClient": 250,
         "RetainedApplicationMessages": {
             "Persist": true,
-            "Filename": "RetainedApplicationMessages.json",
+            "Path": "RetainedApplicationMessages.json",
             "WriteInterval": 10 // In seconds.
         },
         "EnableDebugLogging": false
     },
+    "Scripting": {
+        "ScriptsPath": "Scripts",
+        "IncludePaths": [
+            "Lib",
+            "/usr/lib/python2.7",
+            "C:\\Python27\\Lib"
+        ]
+    },
     "Logging": {
         "LogLevel": {
             "Default": "Debug",

Source/MQTTnet.Server/run.bat

@@ -1,2 +0,0 @@
-@echo off
-START "MQTTnet Server" dotnet .\MQTTnet.Server.dll

Source/MQTTnet.Server/run.sh

@@ -1,3 +0,0 @@
-#!/bin/bash
-echo "Starting MQTTnet Server.."
-dotnet .\MQTTnet.Server.dll

Source/MQTTnet/Adapter/IMqttChannelAdapter.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Formatter;
@@ -12,6 +13,8 @@ namespace MQTTnet.Adapter
 
         bool IsSecureConnection { get; }
 
+        X509Certificate2 ClientCertificate { get; }
+
         MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
 
         long BytesSent { get; }
@@ -29,5 +32,7 @@ namespace MQTTnet.Adapter
         Task SendPacketAsync(MqttBasePacket packet, TimeSpan timeout, CancellationToken cancellationToken);
 
         Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout, CancellationToken cancellationToken);
+
+        void ResetStatistics();
     }
 }

Source/MQTTnet/Adapter/IMqttServerAdapter.cs

@@ -6,7 +6,7 @@ namespace MQTTnet.Adapter
 {
     public interface IMqttServerAdapter : IDisposable
     {
-        Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
+        Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }
 
         Task StartAsync(IMqttServerOptions options);
         Task StopAsync();

Source/MQTTnet/Adapter/MqttChannelAdapter.cs

@@ -2,6 +2,7 @@ using System;
 using System.IO;
 using System.Net.Sockets;
 using System.Runtime.InteropServices;
+using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Channel;
@@ -47,6 +48,8 @@ namespace MQTTnet.Adapter
 
         public bool IsSecureConnection => _channel.IsSecureConnection;
 
+        public X509Certificate2 ClientCertificate => _channel.ClientCertificate;
+
         public MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
 
         public long BytesSent => Interlocked.Read(ref _bytesSent);

Source/MQTTnet/Adapter/MqttServerAdapterClientAcceptedEventArgs.cs

@@ -1,17 +0,0 @@
-using System;
-using System.Threading.Tasks;
-
-namespace MQTTnet.Adapter
-{
-    public class MqttServerAdapterClientAcceptedEventArgs : EventArgs
-    {
-        public MqttServerAdapterClientAcceptedEventArgs(IMqttChannelAdapter channelAdapter)
-        {
-            ChannelAdapter = channelAdapter ?? throw new ArgumentNullException(nameof(channelAdapter));
-        }
-
-        public IMqttChannelAdapter ChannelAdapter { get; }
-
-        public Task SessionTask { get; set; }
-    }
-}

Source/MQTTnet/Adapter/ReceivedMqttPacket.cs

@@ -4,16 +4,16 @@ namespace MQTTnet.Adapter
 {
     public class ReceivedMqttPacket
     {
-        public ReceivedMqttPacket(byte fixedHeader, MqttPacketBodyReader body, int totalLength)
+        public ReceivedMqttPacket(byte fixedHeader, IMqttPacketBodyReader body, int totalLength)
         {
             FixedHeader = fixedHeader;
             Body = body;
             TotalLength = totalLength;
         }
 
-        public byte FixedHeader { get; }
+        public byte FixedHeader { get; set; }
 
-        public MqttPacketBodyReader Body { get; }
+        public IMqttPacketBodyReader Body { get; }
 
         public int TotalLength { get; }
     }

Source/MQTTnet/Channel/IMqttChannel.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -8,6 +9,7 @@ namespace MQTTnet.Channel
     {
         string Endpoint { get; }
         bool IsSecureConnection { get; }
+        X509Certificate2 ClientCertificate { get; }
 
         Task ConnectAsync(CancellationToken cancellationToken);
         Task DisconnectAsync(CancellationToken cancellationToken);

Source/MQTTnet/Client/Connecting/MqttClientAuthenticateResult.cs

@@ -1,9 +1,45 @@
-namespace MQTTnet.Client.Connecting
+using System.Collections.Generic;
+using MQTTnet.Packets;
+
+namespace MQTTnet.Client.Connecting
 {
+    // TODO: Consider renaming this to _MqttClientConnectResult_
     public class MqttClientAuthenticateResult
     {
+        public MqttClientConnectResultCode ResultCode { get; set; }
+
         public bool IsSessionPresent { get; set; }
 
-        public MqttClientConnectResultCode ResultCode { get; set; }
+        public bool? WildcardSubscriptionAvailable { get; set; }
+
+        public bool? RetainAvailable { get; set; }
+
+        public string AssignedClientIdentifier { get; set; }
+
+        public string AuthenticationMethod { get; set; }
+
+        public byte[] AuthenticationData { get; set; }
+
+        public uint? MaximumPacketSize { get; set; }
+
+        public string ReasonString { get; set; }
+
+        public ushort? ReceiveMaximum { get; set; }
+
+        public string ResponseInformation { get; set; }
+
+        public ushort? TopicAliasMaximum { get; set; }
+
+        public string ServerReference { get; set; }
+
+        public ushort? ServerKeepAlive { get; set; }
+
+        public uint? SessionExpiryInterval { get; set; }
+
+        public bool? SubscriptionIdentifiersAvailable { get; set; }
+
+        public bool? SharedSubscriptionAvailable { get; set; }
+
+        public List<MqttUserProperty> UserProperties { get; set; }
     }
 }

Source/MQTTnet/Client/Disconnecting/MqttClientDisconnectedEventArgs.cs

@@ -1,17 +1,21 @@
 using System;
+using MQTTnet.Client.Connecting;
 
 namespace MQTTnet.Client.Disconnecting
 {
     public class MqttClientDisconnectedEventArgs : EventArgs
     {
-        public MqttClientDisconnectedEventArgs(bool clientWasConnected, Exception exception)
+        public MqttClientDisconnectedEventArgs(bool clientWasConnected, Exception exception, MqttClientAuthenticateResult authenticateResult)
         {
             ClientWasConnected = clientWasConnected;
             Exception = exception;
+            AuthenticateResult = authenticateResult;
         }
 
         public bool ClientWasConnected { get; }
 
         public Exception Exception { get; }
+
+        public MqttClientAuthenticateResult AuthenticateResult { get; }
     }
 }

Source/MQTTnet/Client/ExtendedAuthenticationExchange/IMqttExtendedAuthenticationExchangeHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace MQTTnet.Client.ExtendedAuthenticationExchange
+{
+    public interface IMqttExtendedAuthenticationExchangeHandler
+    {
+        Task HandleRequestAsync(MqttExtendedAuthenticationExchangeContext context);
+    }
+}

Source/MQTTnet/Client/ExtendedAuthenticationExchange/MqttExtendedAuthenticationExchangeContext.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Collections.Generic;
+using MQTTnet.Packets;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Client.ExtendedAuthenticationExchange
+{
+    public class MqttExtendedAuthenticationExchangeContext
+    {
+        public MqttExtendedAuthenticationExchangeContext(MqttAuthPacket authPacket, IMqttClient client)
+        {
+            if (authPacket == null) throw new ArgumentNullException(nameof(authPacket));
+
+            ReasonCode = authPacket.ReasonCode;
+            ReasonString = authPacket.Properties?.ReasonString;
+            AuthenticationMethod = authPacket.Properties?.AuthenticationMethod;
+            AuthenticationData = authPacket.Properties?.AuthenticationData;
+            UserProperties = authPacket.Properties?.UserProperties;
+
+            Client = client ?? throw new ArgumentNullException(nameof(client));
+        }
+
+        public MqttAuthenticateReasonCode ReasonCode { get; }
+
+        public string ReasonString { get; }
+
+        public string AuthenticationMethod { get; }
+
+        public byte[] AuthenticationData { get; }
+
+        public List<MqttUserProperty> UserProperties { get; }
+
+        public IMqttClient Client { get; }
+    }
+}

Source/MQTTnet/Client/ExtendedAuthenticationExchange/MqttExtendedAuthenticationExchangeData.cs

@@ -0,0 +1,17 @@
+using System.Collections.Generic;
+using MQTTnet.Packets;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Client.ExtendedAuthenticationExchange
+{
+    public class MqttExtendedAuthenticationExchangeData
+    {
+        public MqttAuthenticateReasonCode ReasonCode { get; set; }
+
+        public string ReasonString { get; set; }
+
+        public byte[] AuthenticationData { get; set; }
+
+        public List<MqttUserProperty> UserProperties { get; }
+    }
+}

Source/MQTTnet/Client/IMqttClient.cs

@@ -3,6 +3,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
+using MQTTnet.Client.ExtendedAuthenticationExchange;
 using MQTTnet.Client.Options;
 using MQTTnet.Client.Subscribing;
 using MQTTnet.Client.Unsubscribing;
@@ -21,6 +22,7 @@ namespace MQTTnet.Client
         Task<MqttClientAuthenticateResult> ConnectAsync(IMqttClientOptions options, CancellationToken cancellationToken);
         Task DisconnectAsync(MqttClientDisconnectOptions options, CancellationToken cancellationToken);
 
+        Task SendExtendedAuthenticationExchangeDataAsync(MqttExtendedAuthenticationExchangeData data, CancellationToken cancellationToken);
         Task<MqttClientSubscribeResult> SubscribeAsync(MqttClientSubscribeOptions options, CancellationToken cancellationToken);
         Task<MqttClientUnsubscribeResult> UnsubscribeAsync(MqttClientUnsubscribeOptions options, CancellationToken cancellationToken);
     }

Source/MQTTnet/Client/IMqttClientFactory.cs

@@ -5,6 +5,8 @@ namespace MQTTnet.Client
 {
     public interface IMqttClientFactory
     {
+        IMqttFactory UseClientAdapterFactory(IMqttClientAdapterFactory clientAdapterFactory);
+
         IMqttClient CreateMqttClient();
 
         IMqttClient CreateMqttClient(IMqttNetLogger logger);

Source/MQTTnet/Client/MqttClient.cs

@@ -5,6 +5,7 @@ using System.Threading.Tasks;
 using MQTTnet.Adapter;
 using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
+using MQTTnet.Client.ExtendedAuthenticationExchange;
 using MQTTnet.Client.Options;
 using MQTTnet.Client.Publishing;
 using MQTTnet.Client.Receiving;
@@ -12,6 +13,7 @@ using MQTTnet.Client.Subscribing;
 using MQTTnet.Client.Unsubscribing;
 using MQTTnet.Diagnostics;
 using MQTTnet.Exceptions;
+using MQTTnet.Internal;
 using MQTTnet.PacketDispatcher;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
@@ -61,6 +63,8 @@ namespace MQTTnet.Client
 
             ThrowIfConnected("It is not allowed to connect with a server after the connection is established.");
 
+            MqttClientAuthenticateResult authenticateResult = null;
+
             try
             {
                 Options = options;
@@ -81,7 +85,7 @@ namespace MQTTnet.Client
 
                 _packetReceiverTask = Task.Run(() => TryReceivePacketsAsync(backgroundCancellationToken), backgroundCancellationToken);
 
-                var authenticateResult = await AuthenticateAsync(adapter, options.WillMessage, cancellationToken).ConfigureAwait(false);
+                authenticateResult = await AuthenticateAsync(adapter, options.WillMessage, cancellationToken).ConfigureAwait(false);
 
                 _sendTracker.Restart();
 
@@ -108,7 +112,7 @@ namespace MQTTnet.Client
 
                 if (!DisconnectIsPending())
                 {
-                    await DisconnectInternalAsync(null, exception).ConfigureAwait(false);
+                    await DisconnectInternalAsync(null, exception, authenticateResult).ConfigureAwait(false);
                 }
 
                 throw;
@@ -131,11 +135,28 @@ namespace MQTTnet.Client
             {
                 if (!DisconnectIsPending())
                 {
-                    await DisconnectInternalAsync(null, null).ConfigureAwait(false);
+                    await DisconnectInternalAsync(null, null, null).ConfigureAwait(false);
                 }
             }
         }
 
+        public Task SendExtendedAuthenticationExchangeDataAsync(MqttExtendedAuthenticationExchangeData data, CancellationToken cancellationToken)
+        {
+            if (data == null) throw new ArgumentNullException(nameof(data));
+
+            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, 
+                    AuthenticationData = data.AuthenticationData,
+                    ReasonString = data.ReasonString,
+                    UserProperties = data.UserProperties
+                }
+            }, cancellationToken);
+        }
+
         public async Task<MqttClientSubscribeResult> SubscribeAsync(MqttClientSubscribeOptions options, CancellationToken cancellationToken)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
@@ -232,7 +253,7 @@ namespace MQTTnet.Client
             if (IsConnected) throw new MqttProtocolViolationException(message);
         }
 
-        private async Task DisconnectInternalAsync(Task sender, Exception exception)
+        private async Task DisconnectInternalAsync(Task sender, Exception exception, MqttClientAuthenticateResult authenticateResult)
         {
             var clientWasConnected = IsConnected;
 
@@ -267,7 +288,9 @@ namespace MQTTnet.Client
                 var disconnectedHandler = DisconnectedHandler;
                 if (disconnectedHandler != null)
                 {
-                    await disconnectedHandler.HandleDisconnectedAsync(new MqttClientDisconnectedEventArgs(clientWasConnected, exception)).ConfigureAwait(false);
+                    // This handler must be executed in a new thread because otherwise a dead lock may happen
+                    // when trying to reconnect in that handler etc.
+                    Task.Run(() => disconnectedHandler.HandleDisconnectedAsync(new MqttClientDisconnectedEventArgs(clientWasConnected, exception, authenticateResult))).Forget(_logger);
                 }
             }
         }
@@ -325,7 +348,7 @@ namespace MQTTnet.Client
                 }
                 catch (MqttCommunicationTimedOutException)
                 {
-                    _logger.Warning(null, "Timeout while waiting for packet of type '{0}'.", typeof(TResponsePacket).Namespace);
+                    _logger.Warning(null, "Timeout while waiting for packet of type '{0}'.", typeof(TResponsePacket).Name);
                     throw;
                 }
             }
@@ -339,6 +362,7 @@ namespace MQTTnet.Client
 
                 while (!cancellationToken.IsCancellationRequested)
                 {
+                    // Values described here: [MQTT-3.1.2-24].
                     var keepAliveSendInterval = TimeSpan.FromSeconds(Options.KeepAlivePeriod.TotalSeconds * 0.75);
                     if (Options.KeepAliveSendInterval.HasValue)
                     {
@@ -376,7 +400,7 @@ namespace MQTTnet.Client
 
                 if (!DisconnectIsPending())
                 {
-                    await DisconnectInternalAsync(_keepAlivePacketsSenderTask, exception).ConfigureAwait(false);
+                    await DisconnectInternalAsync(_keepAlivePacketsSenderTask, exception, null).ConfigureAwait(false);
                 }
             }
             finally
@@ -404,7 +428,7 @@ namespace MQTTnet.Client
                     {
                         if (!DisconnectIsPending())
                         {
-                            await DisconnectInternalAsync(_packetReceiverTask, null).ConfigureAwait(false);
+                            await DisconnectInternalAsync(_packetReceiverTask, null, null).ConfigureAwait(false);
                         }
 
                         return;
@@ -436,7 +460,7 @@ namespace MQTTnet.Client
 
                 if (!DisconnectIsPending())
                 {
-                    await DisconnectInternalAsync(_packetReceiverTask, exception).ConfigureAwait(false);
+                    await DisconnectInternalAsync(_packetReceiverTask, exception, null).ConfigureAwait(false);
                 }
             }
             finally
@@ -467,8 +491,19 @@ namespace MQTTnet.Client
                 }
                 else if (packet is MqttDisconnectPacket)
                 {
+                    // Also dispatch disconnect to waiting threads to generate a proper exception.
+                    _packetDispatcher.Dispatch(packet);
+
                     await DisconnectAsync(null, cancellationToken).ConfigureAwait(false);
                 }
+                else if (packet is MqttAuthPacket authPacket)
+                {
+                    var extendedAuthenticationExchangeHandler = Options.ExtendedAuthenticationExchangeHandler;
+                    if (extendedAuthenticationExchangeHandler != null)
+                    {
+                        await extendedAuthenticationExchangeHandler.HandleRequestAsync(new MqttExtendedAuthenticationExchangeContext(authPacket, this)).ConfigureAwait(false);
+                    }
+                }
                 else
                 {
                     _packetDispatcher.Dispatch(packet);
@@ -497,7 +532,7 @@ namespace MQTTnet.Client
 
                 if (!DisconnectIsPending())
                 {
-                    await DisconnectInternalAsync(_packetReceiverTask, exception).ConfigureAwait(false);
+                    await DisconnectInternalAsync(_packetReceiverTask, exception, null).ConfigureAwait(false);
                 }
             }
         }
@@ -617,4 +652,4 @@ namespace MQTTnet.Client
             return Interlocked.CompareExchange(ref _disconnectGate, 1, 0) != 0;
         }
     }
-}
+}

Source/MQTTnet/Client/MqttClientExtensions.cs

@@ -4,6 +4,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
+using MQTTnet.Client.ExtendedAuthenticationExchange;
 using MQTTnet.Client.Options;
 using MQTTnet.Client.Publishing;
 using MQTTnet.Client.Receiving;
@@ -170,21 +171,36 @@ namespace MQTTnet.Client
 
         public static Task<MqttClientAuthenticateResult> ConnectAsync(this IMqttClient client, IMqttClientOptions options)
         {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+
             return client.ConnectAsync(options, CancellationToken.None);
         }
 
         public static Task DisconnectAsync(this IMqttClient client, MqttClientDisconnectOptions options)
         {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+
             return client.DisconnectAsync(options, CancellationToken.None);
         }
 
+        public static Task SendExtendedAuthenticationExchangeDataAsync(this IMqttClient client, MqttExtendedAuthenticationExchangeData data)
+        {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+
+            return client.SendExtendedAuthenticationExchangeDataAsync(data, CancellationToken.None);
+        }
+
         public static Task<MqttClientSubscribeResult> SubscribeAsync(this IMqttClient client, MqttClientSubscribeOptions options)
         {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+
             return client.SubscribeAsync(options, CancellationToken.None);
         }
 
         public static Task<MqttClientUnsubscribeResult> UnsubscribeAsync(this IMqttClient client, MqttClientUnsubscribeOptions options)
         {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+
             return client.UnsubscribeAsync(options, CancellationToken.None);
         }
 

Source/MQTTnet/Client/Options/IMqttClientCredentials.cs

@@ -2,7 +2,7 @@
 {
     public interface IMqttClientCredentials
     {
-        string Password { get; }
         string Username { get; }
+        byte[] Password { get; }
     }
 }

Source/MQTTnet/Client/Options/IMqttClientOptions.cs

@@ -1,4 +1,5 @@
 using System;
+using MQTTnet.Client.ExtendedAuthenticationExchange;
 using MQTTnet.Formatter;
 
 namespace MQTTnet.Client.Options
@@ -8,6 +9,7 @@ namespace MQTTnet.Client.Options
         string ClientId { get; }
         bool CleanSession { get; }
         IMqttClientCredentials Credentials { get; }
+        IMqttExtendedAuthenticationExchangeHandler ExtendedAuthenticationExchangeHandler { get; }
         MqttProtocolVersion ProtocolVersion { get; }
         IMqttClientChannelOptions ChannelOptions { get; }
         

Source/MQTTnet/Client/Options/MqttClientCredentials.cs

@@ -4,6 +4,6 @@
     {
         public string Username { get; set; }
 
-        public string Password { get; set; }
+        public byte[] Password { get; set; }
     }
 }

Source/MQTTnet/Client/Options/MqttClientOptions.cs

@@ -1,4 +1,5 @@
 using System;
+using MQTTnet.Client.ExtendedAuthenticationExchange;
 using MQTTnet.Formatter;
 
 namespace MQTTnet.Client.Options
@@ -8,6 +9,7 @@ namespace MQTTnet.Client.Options
         public string ClientId { get; set; } = Guid.NewGuid().ToString("N");
         public bool CleanSession { get; set; } = true;
         public IMqttClientCredentials Credentials { get; set; }
+        public IMqttExtendedAuthenticationExchangeHandler ExtendedAuthenticationExchangeHandler { get; set; }
         public MqttProtocolVersion ProtocolVersion { get; set; } = MqttProtocolVersion.V311;
 
         public IMqttClientChannelOptions ChannelOptions { get; set; }

Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs

@@ -1,5 +1,7 @@
 using System;
 using System.Linq;
+using System.Text;
+using MQTTnet.Client.ExtendedAuthenticationExchange;
 using MQTTnet.Formatter;
 
 namespace MQTTnet.Client.Options
@@ -15,6 +17,11 @@ namespace MQTTnet.Client.Options
 
         public MqttClientOptionsBuilder WithProtocolVersion(MqttProtocolVersion value)
         {
+            if (value == MqttProtocolVersion.Unknown)
+            {
+                throw new ArgumentException("Protocol version is invalid.");
+            }
+
             _options.ProtocolVersion = value;
             return this;
         }
@@ -110,6 +117,18 @@ namespace MQTTnet.Client.Options
         }
 
         public MqttClientOptionsBuilder WithCredentials(string username, string password = null)
+        {
+            byte[] passwordBuffer = null;
+
+            if (password != null)
+            {
+                passwordBuffer = Encoding.UTF8.GetBytes(password);
+            }
+
+            return WithCredentials(username, passwordBuffer);
+        }
+
+        public MqttClientOptionsBuilder WithCredentials(string username, byte[] password = null)
         {
             _options.Credentials = new MqttClientCredentials
             {
@@ -120,6 +139,12 @@ namespace MQTTnet.Client.Options
             return this;
         }
 
+        public MqttClientOptionsBuilder WithExtendedAuthenticationExchangeHandler(IMqttExtendedAuthenticationExchangeHandler handler)
+        {
+            _options.ExtendedAuthenticationExchangeHandler = handler;
+            return this;
+        }
+
         public MqttClientOptionsBuilder WithTcpServer(string server, int? port = null)
         {
             _tcpOptions = new MqttClientTcpOptions
@@ -131,6 +156,17 @@ namespace MQTTnet.Client.Options
             return this;
         }
 
+        // TODO: Consider creating _MqttClientTcpOptionsBuilder_ as overload.
+        public MqttClientOptionsBuilder WithTcpServer(Action<MqttClientTcpOptions> optionsBuilder)
+        {
+            if (optionsBuilder == null) throw new ArgumentNullException(nameof(optionsBuilder));
+
+            _tcpOptions = new MqttClientTcpOptions();
+            optionsBuilder.Invoke(_tcpOptions);
+
+            return this;
+        }
+
         public MqttClientOptionsBuilder WithProxy(string address, string username = null, string password = null, string domain = null, bool bypassOnLocal = false, string[] bypassList = null)
         {
             _proxyOptions = new MqttClientWebSocketProxyOptions
@@ -146,6 +182,15 @@ namespace MQTTnet.Client.Options
             return this;
         }
 
+        public MqttClientOptionsBuilder WithProxy(Action<MqttClientWebSocketProxyOptions> optionsBuilder)
+        {
+            if (optionsBuilder == null) throw new ArgumentNullException(nameof(optionsBuilder));
+
+            _proxyOptions = new MqttClientWebSocketProxyOptions();
+            optionsBuilder(_proxyOptions);
+            return this;
+        }
+
         public MqttClientOptionsBuilder WithWebSocketServer(string uri, MqttClientOptionsBuilderWebSocketParameters parameters = null)
         {
             _webSocketOptions = new MqttClientWebSocketOptions
@@ -158,9 +203,19 @@ namespace MQTTnet.Client.Options
             return this;
         }
 
+        public MqttClientOptionsBuilder WithWebSocketServer(Action<MqttClientWebSocketOptions> optionsBuilder)
+        {
+            if (optionsBuilder == null) throw new ArgumentNullException(nameof(optionsBuilder));
+
+            _webSocketOptions = new MqttClientWebSocketOptions();
+            optionsBuilder.Invoke(_webSocketOptions);
+
+            return this;
+        }
+
         public MqttClientOptionsBuilder WithTls(MqttClientOptionsBuilderTlsParameters parameters)
         {
-            _tlsParameters = parameters ?? throw new ArgumentNullException(nameof(parameters));
+            _tlsParameters = parameters;
             return this;
         }
 
@@ -169,6 +224,15 @@ namespace MQTTnet.Client.Options
             return WithTls(new MqttClientOptionsBuilderTlsParameters { UseTls = true });
         }
 
+        public MqttClientOptionsBuilder WithTls(Action<MqttClientOptionsBuilderTlsParameters> optionsBuilder)
+        {
+            if (optionsBuilder == null) throw new ArgumentNullException(nameof(optionsBuilder));
+
+            _tlsParameters = new MqttClientOptionsBuilderTlsParameters();
+            optionsBuilder(_tlsParameters);
+            return this;
+        }
+
         public IMqttClientOptions Build()
         {
             if (_tcpOptions == null && _webSocketOptions == null)

Source/MQTTnet/Client/Options/MqttClientTcpOptions.cs

@@ -8,9 +8,9 @@ namespace MQTTnet.Client.Options
 
         public int? Port { get; set; }
 
-        public int BufferSize { get; set; } = 1024;
+        public int BufferSize { get; set; } = 65536;
 
-        public bool DualMode { get; set; } = true;
+        public bool? DualMode { get; set; }
 
         public bool NoDelay { get; set; } = true;
 

Source/MQTTnet/Client/Publishing/MqttClientPublishResult.cs

@@ -1,8 +1,17 @@
 
+using System.Collections.Generic;
+using MQTTnet.Packets;
+
 namespace MQTTnet.Client.Publishing
 {
     public class MqttClientPublishResult
     {
+        public ushort? PacketIdentifier { get; set; }
+
         public MqttClientPublishReasonCode ReasonCode { get; set; } = MqttClientPublishReasonCode.Success;
+
+        public string ReasonString { get; set; }
+
+        public List<MqttUserProperty> UserProperties { get; set; }
     }
 }

Source/MQTTnet/Client/Subscribing/MqttClientSubscribeOptions.cs

@@ -7,6 +7,8 @@ namespace MQTTnet.Client.Subscribing
     {
         public List<TopicFilter> TopicFilters { get; set; } = new List<TopicFilter>();
 
-        public List<MqttUserProperty> UserProperties { get; set; } = new List<MqttUserProperty>();
+        public uint? SubscriptionIdentifier { get; set; }
+
+        public List<MqttUserProperty> UserProperties { get; set; }
     }
 }

Source/MQTTnet/Client/Subscribing/MqttClientSubscribeOptionsBuilder.cs

@@ -0,0 +1,87 @@
+using System;
+using System.Collections.Generic;
+using MQTTnet.Packets;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Client.Subscribing
+{
+    public class MqttClientSubscribeOptionsBuilder
+    {
+        private readonly MqttClientSubscribeOptions _subscribeOptions = new MqttClientSubscribeOptions();
+
+        public MqttClientSubscribeOptionsBuilder WithUserProperty(string name, string value)
+        {
+            if (name == null) throw new ArgumentNullException(nameof(name));
+            if (value == null) throw new ArgumentNullException(nameof(value));
+
+            if (_subscribeOptions.UserProperties == null)
+            {
+                _subscribeOptions.UserProperties = new List<MqttUserProperty>();
+            }
+
+            _subscribeOptions.UserProperties.Add(new MqttUserProperty(name, value));
+
+            return this;
+        }
+
+        public MqttClientSubscribeOptionsBuilder WithSubscriptionIdentifier(uint? subscriptionIdentifier)
+        {
+            _subscribeOptions.SubscriptionIdentifier = subscriptionIdentifier;
+
+            return this;
+        }
+
+        public MqttClientSubscribeOptionsBuilder WithTopicFilter(
+            string topic,
+            MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce,
+            bool? noLocal = null,
+            bool? retainAsPublished = null,
+            MqttRetainHandling? retainHandling = null)
+        {
+            return WithTopicFilter(new TopicFilter
+            {
+                Topic = topic,
+                QualityOfServiceLevel = qualityOfServiceLevel,
+                NoLocal = noLocal,
+                RetainAsPublished = retainAsPublished,
+                RetainHandling = retainHandling
+            });
+        }
+
+        public MqttClientSubscribeOptionsBuilder WithTopicFilter(Action<TopicFilterBuilder> topicFilterBuilder)
+        {
+            if (topicFilterBuilder == null) throw new ArgumentNullException(nameof(topicFilterBuilder));
+
+            var internalTopicFilterBuilder = new TopicFilterBuilder();
+            topicFilterBuilder(internalTopicFilterBuilder);
+
+            return WithTopicFilter(internalTopicFilterBuilder);
+        }
+
+        public MqttClientSubscribeOptionsBuilder WithTopicFilter(TopicFilterBuilder topicFilterBuilder)
+        {
+            if (topicFilterBuilder == null) throw new ArgumentNullException(nameof(topicFilterBuilder));
+
+            return WithTopicFilter(topicFilterBuilder.Build());
+        }
+
+        public MqttClientSubscribeOptionsBuilder WithTopicFilter(TopicFilter topicFilter)
+        {
+            if (topicFilter == null) throw new ArgumentNullException(nameof(topicFilter));
+
+            if (_subscribeOptions.TopicFilters == null)
+            {
+                _subscribeOptions.TopicFilters = new List<TopicFilter>();
+            }
+
+            _subscribeOptions.TopicFilters.Add(topicFilter);
+
+            return this;
+        }
+
+        public MqttClientSubscribeOptions Build()
+        {
+            return _subscribeOptions;
+        }
+    }
+}

Source/MQTTnet/Exceptions/MqttUnexpectedDisconnectReceivedException.cs

@@ -0,0 +1,29 @@
+using System.Collections.Generic;
+using MQTTnet.Packets;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Exceptions
+{
+    public class MqttUnexpectedDisconnectReceivedException : MqttCommunicationException
+    {
+        public MqttUnexpectedDisconnectReceivedException(MqttDisconnectPacket disconnectPacket) 
+            : base($"Unexpected DISCONNECT (Reason code={disconnectPacket.ReasonCode}) received.")
+        {
+            ReasonCode = disconnectPacket.ReasonCode;
+            SessionExpiryInterval = disconnectPacket.Properties?.SessionExpiryInterval;
+            ReasonString = disconnectPacket.Properties?.ReasonString;
+            ServerReference = disconnectPacket.Properties?.ServerReference;
+            UserProperties = disconnectPacket.Properties?.UserProperties;
+        }
+
+        public MqttDisconnectReasonCode? ReasonCode { get; }
+
+        public uint? SessionExpiryInterval { get; }
+
+        public string ReasonString { get; }
+
+        public List<MqttUserProperty> UserProperties { get; }
+
+        public string ServerReference { get; }
+    }
+}

Source/MQTTnet/Formatter/IMqttDataConverter.cs

@@ -5,6 +5,8 @@ using MQTTnet.Client.Publishing;
 using MQTTnet.Client.Subscribing;
 using MQTTnet.Client.Unsubscribing;
 using MQTTnet.Packets;
+using MQTTnet.Server;
+using MqttClientSubscribeResult = MQTTnet.Client.Subscribing.MqttClientSubscribeResult;
 
 namespace MQTTnet.Formatter
 {
@@ -12,12 +14,16 @@ namespace MQTTnet.Formatter
     {
         MqttPublishPacket CreatePublishPacket(MqttApplicationMessage applicationMessage);
 
+        MqttPubAckPacket CreatePubAckPacket(MqttPublishPacket publishPacket);
+
         MqttApplicationMessage CreateApplicationMessage(MqttPublishPacket publishPacket);
 
         MqttClientAuthenticateResult CreateClientConnectResult(MqttConnAckPacket connAckPacket);
 
         MqttConnectPacket CreateConnectPacket(MqttApplicationMessage willApplicationMessage, IMqttClientOptions options);
 
+        MqttConnAckPacket CreateConnAckPacket(MqttConnectionValidatorContext connectionValidatorContext);
+
         MqttClientSubscribeResult CreateClientSubscribeResult(MqttSubscribePacket subscribePacket, MqttSubAckPacket subAckPacket);
 
         MqttClientUnsubscribeResult CreateClientUnsubscribeResult(MqttUnsubscribePacket unsubscribePacket, MqttUnsubAckPacket unsubAckPacket);

Source/MQTTnet/Formatter/IMqttPacketBodyReader.cs

@@ -0,0 +1,31 @@
+using System;
+
+namespace MQTTnet.Formatter
+{
+    public interface IMqttPacketBodyReader
+    {
+        int Length { get; }
+
+        int Offset { get; }
+
+        bool EndOfStream { get; }
+
+        byte ReadByte();
+
+        byte[] ReadRemainingData();
+
+        ushort ReadTwoByteInteger();
+
+        string ReadStringWithLengthPrefix();
+
+        byte[] ReadWithLengthPrefix();
+
+        uint ReadFourByteInteger();
+
+        uint ReadVariableLengthInteger();
+
+        bool ReadBoolean();
+
+        void Seek(int position);
+    }
+}

Source/MQTTnet/Formatter/IMqttPacketWriter.cs

@@ -0,0 +1,19 @@
+namespace MQTTnet.Formatter
+{
+    public interface IMqttPacketWriter
+    {
+        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 FreeBuffer();
+        byte[] GetBuffer();
+    }
+}

Source/MQTTnet/Formatter/MqttPacketBodyReader.cs

@@ -1,59 +1,50 @@
 using System;
+using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Text;
 using MQTTnet.Exceptions;
 
 namespace MQTTnet.Formatter
 {
-    public class MqttPacketBodyReader
+    public class MqttPacketBodyReader : IMqttPacketBodyReader
     {
         private readonly byte[] _buffer;
-        private readonly ulong _initialOffset;
-        private readonly ulong _length;
+        private readonly int _initialOffset;
+        private readonly int _length;
+
+        private int _offset;
 
         public MqttPacketBodyReader(byte[] buffer, int offset, int length)
-         : this(buffer, (ulong)offset, (ulong)length)
-        {
-        }
-
-        public MqttPacketBodyReader(byte[] buffer, ulong offset, ulong length)
         {
             _buffer = buffer;
             _initialOffset = offset;
-            Offset = offset;
+            _offset = offset;
             _length = length;
         }
 
-        public ulong Offset { get; private set; }
+        public int Offset => _offset;
 
-        public ulong Length => _length - Offset;
+        public int Length => _length - _offset;
 
-        public bool EndOfStream => Offset == _length;
+        public bool EndOfStream => _offset == _length;
 
-        public void Seek(ulong position)
+        public void Seek(int position)
         {
-            Offset = _initialOffset + position;
-        }
-
-        public ArraySegment<byte> Read(uint length)
-        {
-            ValidateReceiveBuffer(length);
-
-            var buffer = new ArraySegment<byte>(_buffer, (int)Offset, (int)length);
-            Offset += length;
-            return buffer;
+            _offset = _initialOffset + position;
         }
 
         public byte ReadByte()
         {
             ValidateReceiveBuffer(1);
-            return _buffer[Offset++];
-        }
 
+            return _buffer[_offset++];
+        }
+        
         public bool ReadBoolean()
         {
             ValidateReceiveBuffer(1);
-            var buffer = _buffer[Offset++];
+
+            var buffer = _buffer[_offset++];
 
             if (buffer == 0)
             {
@@ -68,17 +59,21 @@ namespace MQTTnet.Formatter
             throw new MqttProtocolViolationException("Boolean values can be 0 or 1 only.");
         }
 
-        public ArraySegment<byte> ReadRemainingData()
+        public byte[] ReadRemainingData()
         {
-            return new ArraySegment<byte>(_buffer, (int)Offset, (int)(_length - Offset));
+            var bufferLength = _length - _offset;
+            var buffer = new byte[bufferLength];
+            Array.Copy(_buffer, _offset, buffer, 0, bufferLength);
+
+            return buffer;
         }
 
         public ushort ReadTwoByteInteger()
         {
             ValidateReceiveBuffer(2);
 
-            var msb = _buffer[Offset++];
-            var lsb = _buffer[Offset++];
+            var msb = _buffer[_offset++];
+            var lsb = _buffer[_offset++];
             
             return (ushort)(msb << 8 | lsb);
         }
@@ -87,26 +82,14 @@ namespace MQTTnet.Formatter
         {
             ValidateReceiveBuffer(4);
 
-            var byte0 = _buffer[Offset++];
-            var byte1 = _buffer[Offset++];
-            var byte2 = _buffer[Offset++];
-            var byte3 = _buffer[Offset++];
+            var byte0 = _buffer[_offset++];
+            var byte1 = _buffer[_offset++];
+            var byte2 = _buffer[_offset++];
+            var byte3 = _buffer[_offset++];
 
             return (uint)(byte0 << 24 | byte1 << 16 | byte2 << 8 | byte3);
         }
 
-        public ArraySegment<byte> ReadWithLengthPrefix()
-        {
-            var length = ReadTwoByteInteger();
-
-            ValidateReceiveBuffer(length);
-
-            var result = new ArraySegment<byte>(_buffer, (int)Offset, length);
-            Offset += length;
-
-            return result;
-        }
-
         public uint ReadVariableLengthInteger()
         {
             var multiplier = 1;
@@ -128,19 +111,36 @@ namespace MQTTnet.Formatter
 
             return value;
         }
+        
+        public byte[] ReadWithLengthPrefix()
+        {
+            return ReadSegmentWithLengthPrefix().ToArray();
+        }
+
+        private ArraySegment<byte> ReadSegmentWithLengthPrefix()
+        {
+            var length = ReadTwoByteInteger();
+
+            ValidateReceiveBuffer(length);
+
+            var result = new ArraySegment<byte>(_buffer, _offset, length);
+            _offset += length;
+
+            return result;
+        }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void ValidateReceiveBuffer(uint length)
+        private void ValidateReceiveBuffer(int length)
         {
-            if (_length < Offset + length)
+            if (_length < _offset + length)
             {
-                throw new ArgumentOutOfRangeException(nameof(_buffer), $"Expected at least {Offset + length} bytes but there are only {_length} bytes");
+                throw new ArgumentOutOfRangeException(nameof(_buffer), $"Expected at least {_offset + length} bytes but there are only {_length} bytes");
             }
         }
 
         public string ReadStringWithLengthPrefix()
         {
-            var buffer = ReadWithLengthPrefix();
+            var buffer = ReadSegmentWithLengthPrefix();
             return Encoding.UTF8.GetString(buffer.Array, buffer.Offset, buffer.Count);
         }
     }

Source/MQTTnet/Formatter/MqttPacketFormatterAdapter.cs

@@ -12,14 +12,26 @@ namespace MQTTnet.Formatter
         private IMqttPacketFormatter _formatter;
 
         public MqttPacketFormatterAdapter()
+            : this(new MqttPacketWriter())
+        {
+        }
+               
+        public MqttPacketFormatterAdapter(MqttProtocolVersion protocolVersion)
+            : this(protocolVersion, new MqttPacketWriter())
         {
         }
 
-        public MqttPacketFormatterAdapter(MqttProtocolVersion protocolVersion)
+        public MqttPacketFormatterAdapter(MqttProtocolVersion protocolVersion, IMqttPacketWriter writer)
+            : this(writer)
         {
             UseProtocolVersion(protocolVersion);
         }
 
+        public MqttPacketFormatterAdapter(IMqttPacketWriter writer)
+        {
+            Writer = writer;
+        }        
+
         public MqttProtocolVersion ProtocolVersion { get; private set; } = MqttProtocolVersion.Unknown;
 
         public IMqttDataConverter DataConverter
@@ -31,6 +43,8 @@ namespace MQTTnet.Formatter
                 return _formatter.DataConverter;
             }
         }
+                
+        public IMqttPacketWriter Writer { get; }
 
         public ArraySegment<byte> Encode(MqttBasePacket packet)
         {
@@ -75,28 +89,30 @@ namespace MQTTnet.Formatter
             }
 
             ProtocolVersion = protocolVersion;
+            _formatter = GetMqttPacketFormatter(protocolVersion, Writer);
+        }
 
+        public static IMqttPacketFormatter GetMqttPacketFormatter(MqttProtocolVersion protocolVersion, IMqttPacketWriter writer)
+        {
+            if (protocolVersion == MqttProtocolVersion.Unknown)
+            {
+                throw new InvalidOperationException("MQTT protocol version is invalid.");
+            }
+            
             switch (protocolVersion)
             {
                 case MqttProtocolVersion.V500:
                     {
-                        _formatter = new MqttV500PacketFormatter();
-                        break;
+                        return new MqttV500PacketFormatter(writer);
                     }
-
                 case MqttProtocolVersion.V311:
                     {
-                        _formatter = new MqttV311PacketFormatter();
-                        break;
+                        return new MqttV311PacketFormatter(writer);
                     }
-
                 case MqttProtocolVersion.V310:
                     {
-
-                        _formatter = new MqttV310PacketFormatter();
-                        break;
+                        return new MqttV310PacketFormatter(writer);
                     }
-                    
                 default:
                     {
                         throw new NotSupportedException();

Source/MQTTnet/Formatter/MqttPacketWriter.cs

@@ -11,7 +11,7 @@ namespace MQTTnet.Formatter
     /// same as for the original MemoryStream in .net. Also this implementation allows accessing the internal
     /// buffer for all platforms and .net framework versions (which is not available at the regular MemoryStream).
     /// </summary>
-    public class MqttPacketWriter
+    public class MqttPacketWriter : IMqttPacketWriter
     {
         private static readonly ArraySegment<byte> ZeroVariableLengthIntegerArray = new ArraySegment<byte>(new byte[1], 0, 1);
         private static readonly ArraySegment<byte> ZeroTwoByteIntegerArray = new ArraySegment<byte>(new byte[2], 0, 2);
@@ -19,7 +19,6 @@ namespace MQTTnet.Formatter
         public static int InitialBufferSize = 128;
         public static int MaxBufferSize = 4096;
 
-        // TODO: Consider using the ArrayPool here together with FreeBuffer.
         private byte[] _buffer = new byte[InitialBufferSize];
 
         private int _offset;
@@ -33,6 +32,19 @@ namespace MQTTnet.Formatter
             return (byte)fixedHeader;
         }
 
+        public static int GetLengthOfVariableInteger(uint value)
+        {
+            var result = 0;
+            var x = value;
+            do
+            {
+                x = x / 128;
+                result++;
+            } while (x > 0);
+
+            return result;
+        }
+
         public static ArraySegment<byte> EncodeVariableLengthInteger(uint value)
         {
             if (value == 0)
@@ -79,24 +91,21 @@ namespace MQTTnet.Formatter
             else
             {
                 WriteWithLengthPrefix(Encoding.UTF8.GetBytes(value));
-            }         
+            }
         }
 
         public void WriteWithLengthPrefix(byte[] value)
         {
-            if (value == null) throw new ArgumentNullException(nameof(value));
-
-            EnsureAdditionalCapacity(value.Length + 2);
-
-            if (value.Length == 0)
+            if (value == null || value.Length == 0)
             {
-                Write(ZeroTwoByteIntegerArray);   
+                Write(ZeroTwoByteIntegerArray);
             }
             else
             {
+                EnsureAdditionalCapacity(value.Length + 2);
                 Write((ushort)value.Length);
                 Write(value, 0, value.Length);
-            }           
+            }
         }
 
         public void Write(byte @byte)
@@ -131,17 +140,23 @@ namespace MQTTnet.Formatter
             Array.Copy(buffer, offset, _buffer, _offset, count);
             IncreasePosition(count);
         }
-        
-        public void Write(MqttPacketWriter propertyWriter)
+
+        public void Write(IMqttPacketWriter propertyWriter)
         {
             if (propertyWriter == null) throw new ArgumentNullException(nameof(propertyWriter));
 
-            if (propertyWriter.Length == 0)
+            if (propertyWriter is MqttPacketWriter writer)
             {
+                if (writer.Length == 0)
+                {
+                    return;
+                }
+
+                Write(writer._buffer, 0, writer.Length);
                 return;
             }
 
-            Write(propertyWriter._buffer, 0, propertyWriter.Length);
+            throw new InvalidOperationException($"{nameof(propertyWriter)} must be of type {typeof(MqttPacketWriter).Name}");
         }
 
         public void Reset(int length)

Source/MQTTnet/Formatter/V3/MqttV310DataConverter.cs

@@ -9,6 +9,8 @@ using MQTTnet.Client.Unsubscribing;
 using MQTTnet.Exceptions;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
+using MQTTnet.Server;
+using MqttClientSubscribeResult = MQTTnet.Client.Subscribing.MqttClientSubscribeResult;
 
 namespace MQTTnet.Formatter.V3
 {
@@ -33,6 +35,15 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
+        public MqttPubAckPacket CreatePubAckPacket(MqttPublishPacket publishPacket)
+        {
+            return new MqttPubAckPacket
+            {
+                PacketIdentifier = publishPacket.PacketIdentifier,
+                ReasonCode = MqttPubAckReasonCode.Success
+            };
+        }
+
         public MqttApplicationMessage CreateApplicationMessage(MqttPublishPacket publishPacket)
         {
             if (publishPacket == null) throw new ArgumentNullException(nameof(publishPacket));
@@ -115,6 +126,16 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
+        public MqttConnAckPacket CreateConnAckPacket(MqttConnectionValidatorContext connectionValidatorContext)
+        {
+            if (connectionValidatorContext == null) throw new ArgumentNullException(nameof(connectionValidatorContext));
+
+            return new MqttConnAckPacket
+            {
+                ReturnCode = new MqttConnectReasonCodeConverter().ToConnectReturnCode(connectionValidatorContext.ReasonCode)
+            };
+        }
+
         public MqttClientSubscribeResult CreateClientSubscribeResult(MqttSubscribePacket subscribePacket, MqttSubAckPacket subAckPacket)
         {
             if (subscribePacket == null) throw new ArgumentNullException(nameof(subscribePacket));
@@ -190,6 +211,7 @@ namespace MQTTnet.Formatter.V3
         {
             return new MqttClientPublishResult
             {
+                PacketIdentifier = pubAckPacket?.PacketIdentifier,
                 ReasonCode = MqttClientPublishReasonCode.Success
             };
         }
@@ -206,6 +228,7 @@ namespace MQTTnet.Formatter.V3
 
             return new MqttClientPublishResult
             {
+                PacketIdentifier = pubCompPacket.PacketIdentifier,
                 ReasonCode = MqttClientPublishReasonCode.Success
             };
         }

Source/MQTTnet/Formatter/V3/MqttV310PacketFormatter.cs

@@ -2,7 +2,6 @@
 using System.Linq;
 using MQTTnet.Adapter;
 using MQTTnet.Exceptions;
-using MQTTnet.Internal;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
 
@@ -12,7 +11,23 @@ namespace MQTTnet.Formatter.V3
     {
         private const int FixedHeaderSize = 1;
 
-        private readonly MqttPacketWriter _packetWriter = new MqttPacketWriter();
+        private static readonly MqttPingReqPacket PingReqPacket = new MqttPingReqPacket();
+        private static readonly MqttPingRespPacket PingRespPacket = new MqttPingRespPacket();
+        private static readonly MqttDisconnectPacket DisconnectPacket = new MqttDisconnectPacket();
+
+        private readonly IMqttPacketWriter _packetWriter;
+
+        public MqttV310PacketFormatter()
+            : this(new MqttPacketWriter())
+        {
+
+        }
+
+        public MqttV310PacketFormatter(IMqttPacketWriter packetWriter)
+        {
+            _packetWriter = packetWriter;
+        }
+
 
         public IMqttDataConverter DataConverter { get; } = new MqttV310DataConverter();
 
@@ -27,17 +42,18 @@ namespace MQTTnet.Formatter.V3
             var fixedHeader = EncodePacket(packet, _packetWriter);
             var remainingLength = (uint)(_packetWriter.Length - 5);
 
-            var remainingLengthBuffer = MqttPacketWriter.EncodeVariableLengthInteger(remainingLength);
+            var remainingLengthSize = MqttPacketWriter.GetLengthOfVariableInteger(remainingLength);
 
-            var headerSize = FixedHeaderSize + remainingLengthBuffer.Count;
+            var headerSize = FixedHeaderSize + remainingLengthSize;
             var headerOffset = 5 - headerSize;
 
             // Position cursor on correct offset on beginning of array (has leading 0x0)
             _packetWriter.Seek(headerOffset);
             _packetWriter.Write(fixedHeader);
-            _packetWriter.Write(remainingLengthBuffer.Array, remainingLengthBuffer.Offset, remainingLengthBuffer.Count);
+            _packetWriter.WriteVariableLengthInteger(remainingLength);
 
             var buffer = _packetWriter.GetBuffer();
+
             return new ArraySegment<byte>(buffer, headerOffset, _packetWriter.Length - headerOffset);
         }
 
@@ -55,18 +71,18 @@ namespace MQTTnet.Formatter.V3
             {
                 case MqttControlPacketType.Connect: return DecodeConnectPacket(receivedMqttPacket.Body);
                 case MqttControlPacketType.ConnAck: return DecodeConnAckPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.Disconnect: return new MqttDisconnectPacket();
-                case MqttControlPacketType.Publish: return DecodePublish(receivedMqttPacket);
-                case MqttControlPacketType.PubAck: return DecodePubAck(receivedMqttPacket.Body);
-                case MqttControlPacketType.PubRec: return DecodePubRec(receivedMqttPacket.Body);
-                case MqttControlPacketType.PubRel: return DecodePubRel(receivedMqttPacket.Body);
-                case MqttControlPacketType.PubComp: return DecodePubComp(receivedMqttPacket.Body);
-                case MqttControlPacketType.PingReq: return new MqttPingReqPacket();
-                case MqttControlPacketType.PingResp: return new MqttPingRespPacket();
-                case MqttControlPacketType.Subscribe: return DecodeSubscribe(receivedMqttPacket.Body);
-                case MqttControlPacketType.SubAck: return DecodeSubAck(receivedMqttPacket.Body);
-                case MqttControlPacketType.Unsubscibe: return DecodeUnsubscribe(receivedMqttPacket.Body);
-                case MqttControlPacketType.UnsubAck: return DecodeUnsubAck(receivedMqttPacket.Body);
+                case MqttControlPacketType.Disconnect: return DisconnectPacket;
+                case MqttControlPacketType.Publish: return DecodePublishPacket(receivedMqttPacket);
+                case MqttControlPacketType.PubAck: return DecodePubAckPacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.PubRec: return DecodePubRecPacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.PubRel: return DecodePubRelPacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.PubComp: return DecodePubCompPacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.PingReq: return PingReqPacket;
+                case MqttControlPacketType.PingResp: return PingRespPacket;
+                case MqttControlPacketType.Subscribe: return DecodeSubscribePacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.SubAck: return DecodeSubAckPacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.Unsubscibe: return DecodeUnsubscribePacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.UnsubAck: return DecodeUnsubAckPacket(receivedMqttPacket.Body);
 
                 default: throw new MqttProtocolViolationException($"Packet type ({controlPacketType}) not supported.");
             }
@@ -77,7 +93,7 @@ namespace MQTTnet.Formatter.V3
             _packetWriter.FreeBuffer();
         }
 
-        private byte EncodePacket(MqttBasePacket packet, MqttPacketWriter packetWriter)
+        private byte EncodePacket(MqttBasePacket packet, IMqttPacketWriter packetWriter)
         {
             switch (packet)
             {
@@ -100,7 +116,7 @@ namespace MQTTnet.Formatter.V3
             }
         }
 
-        private static MqttBasePacket DecodeUnsubAck(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeUnsubAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -110,7 +126,7 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
-        private static MqttBasePacket DecodePubComp(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodePubCompPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -120,7 +136,7 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
-        private static MqttBasePacket DecodePubRel(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodePubRelPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -130,7 +146,7 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
-        private static MqttBasePacket DecodePubRec(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodePubRecPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -140,7 +156,7 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
-        private static MqttBasePacket DecodePubAck(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodePubAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -150,7 +166,7 @@ namespace MQTTnet.Formatter.V3
             };
         }
 
-        private static MqttBasePacket DecodeUnsubscribe(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeUnsubscribePacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -167,7 +183,7 @@ namespace MQTTnet.Formatter.V3
             return packet;
         }
 
-        private static MqttBasePacket DecodeSubscribe(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeSubscribePacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -190,7 +206,7 @@ namespace MQTTnet.Formatter.V3
             return packet;
         }
 
-        private static MqttBasePacket DecodePublish(ReceivedMqttPacket receivedMqttPacket)
+        private static MqttBasePacket DecodePublishPacket(ReceivedMqttPacket receivedMqttPacket)
         {
             ThrowIfBodyIsEmpty(receivedMqttPacket.Body);
 
@@ -211,23 +227,36 @@ namespace MQTTnet.Formatter.V3
                 PacketIdentifier = packetIdentifier,
                 Retain = retain,
                 Topic = topic,
-                Payload = receivedMqttPacket.Body.ReadRemainingData().ToArray(),
                 QualityOfServiceLevel = qualityOfServiceLevel,
                 Dup = dup
             };
 
+            if (!receivedMqttPacket.Body.EndOfStream)
+            {
+                packet.Payload = receivedMqttPacket.Body.ReadRemainingData();
+            }
+
             return packet;
         }
 
-        private MqttBasePacket DecodeConnectPacket(MqttPacketBodyReader body)
+        private MqttBasePacket DecodeConnectPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
-            var packet = new MqttConnectPacket
+            var protocolName = body.ReadStringWithLengthPrefix();
+            var protocolVersion = body.ReadByte();
+
+            if (protocolName != "MQTT" && protocolName != "MQIsdp")
             {
-                ProtocolName = body.ReadStringWithLengthPrefix(),
-                ProtocolLevel = body.ReadByte()
-            };
+                throw new MqttProtocolViolationException("MQTT protocol name do not match MQTT v3.");
+            }
+
+            if (protocolVersion != 3 && protocolVersion != 4)
+            {
+                throw new MqttProtocolViolationException("MQTT protocol version do not match MQTT v3.");
+            }
+
+            var packet = new MqttConnectPacket();
 
             var connectFlags = body.ReadByte();
             if ((connectFlags & 0x1) > 0)
@@ -251,7 +280,7 @@ namespace MQTTnet.Formatter.V3
                 packet.WillMessage = new MqttApplicationMessage
                 {
                     Topic = body.ReadStringWithLengthPrefix(),
-                    Payload = body.ReadWithLengthPrefix().ToArray(),
+                    Payload = body.ReadWithLengthPrefix(),
                     QualityOfServiceLevel = (MqttQualityOfServiceLevel)willQoS,
                     Retain = willRetain
                 };
@@ -264,14 +293,14 @@ namespace MQTTnet.Formatter.V3
 
             if (passwordFlag)
             {
-                packet.Password = body.ReadStringWithLengthPrefix();
+                packet.Password = body.ReadWithLengthPrefix();
             }
 
             ValidateConnectPacket(packet);
             return packet;
         }
 
-        private static MqttBasePacket DecodeSubAck(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeSubAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -288,7 +317,7 @@ namespace MQTTnet.Formatter.V3
             return packet;
         }
 
-        protected virtual MqttBasePacket DecodeConnAckPacket(MqttPacketBodyReader body)
+        protected virtual MqttBasePacket DecodeConnAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -319,7 +348,7 @@ namespace MQTTnet.Formatter.V3
             }
         }
 
-        protected virtual byte EncodeConnectPacket(MqttConnectPacket packet, MqttPacketWriter packetWriter)
+        protected virtual byte EncodeConnectPacket(MqttConnectPacket packet, IMqttPacketWriter packetWriter)
         {
             ValidateConnectPacket(packet);
 
@@ -381,7 +410,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Connect);
         }
 
-        protected virtual byte EncodeConnAckPacket(MqttConnAckPacket packet, MqttPacketWriter packetWriter)
+        protected virtual byte EncodeConnAckPacket(MqttConnAckPacket packet, IMqttPacketWriter packetWriter)
         {
             packetWriter.Write(0); // Reserved.
             packetWriter.Write((byte)packet.ReturnCode.Value);
@@ -389,7 +418,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.ConnAck);
         }
 
-        private static byte EncodePubRelPacket(MqttPubRelPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePubRelPacket(MqttPubRelPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -401,7 +430,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubRel, 0x02);
         }
 
-        private static byte EncodePublishPacket(MqttPublishPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePublishPacket(MqttPublishPacket packet, IMqttPacketWriter packetWriter)
         {
             ValidatePublishPacket(packet);
 
@@ -446,7 +475,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Publish, fixedHeader);
         }
 
-        private static byte EncodePubAckPacket(MqttPubAckPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePubAckPacket(MqttPubAckPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -458,7 +487,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubAck);
         }
 
-        private static byte EncodePubRecPacket(MqttPubRecPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePubRecPacket(MqttPubRecPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -470,7 +499,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubRec);
         }
 
-        private static byte EncodePubCompPacket(MqttPubCompPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePubCompPacket(MqttPubCompPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -482,7 +511,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubComp);
         }
 
-        private static byte EncodeSubscribePacket(MqttSubscribePacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeSubscribePacket(MqttSubscribePacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.TopicFilters.Any()) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.8.3-3].");
 
@@ -505,7 +534,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Subscribe, 0x02);
         }
 
-        private static byte EncodeSubAckPacket(MqttSubAckPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeSubAckPacket(MqttSubAckPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -525,7 +554,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.SubAck);
         }
 
-        private static byte EncodeUnsubscribePacket(MqttUnsubscribePacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeUnsubscribePacket(MqttUnsubscribePacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.TopicFilters.Any()) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.10.3-2].");
 
@@ -547,7 +576,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Unsubscibe, 0x02);
         }
 
-        private static byte EncodeUnsubAckPacket(MqttUnsubAckPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeUnsubAckPacket(MqttUnsubAckPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.PacketIdentifier.HasValue)
             {
@@ -564,7 +593,7 @@ namespace MQTTnet.Formatter.V3
         }
 
         // ReSharper disable once ParameterOnlyUsedForPreconditionCheck.Local
-        protected static void ThrowIfBodyIsEmpty(MqttPacketBodyReader body)
+        protected static void ThrowIfBodyIsEmpty(IMqttPacketBodyReader body)
         {
             if (body == null || body.Length == 0)
             {

Source/MQTTnet/Formatter/V3/MqttV311PacketFormatter.cs

@@ -6,7 +6,17 @@ namespace MQTTnet.Formatter.V3
 {
     public class MqttV311PacketFormatter : MqttV310PacketFormatter
     {
-        protected override byte EncodeConnectPacket(MqttConnectPacket packet, MqttPacketWriter packetWriter)
+        public MqttV311PacketFormatter()
+            : base()
+        {
+        }
+
+        public MqttV311PacketFormatter(IMqttPacketWriter packetWriter)
+            : base(packetWriter)
+        {
+        }
+
+        protected override byte EncodeConnectPacket(MqttConnectPacket packet, IMqttPacketWriter packetWriter)
         {
             ValidateConnectPacket(packet);
 
@@ -68,7 +78,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Connect);
         }
 
-        protected override byte EncodeConnAckPacket(MqttConnAckPacket packet, MqttPacketWriter packetWriter)
+        protected override byte EncodeConnAckPacket(MqttConnAckPacket packet, IMqttPacketWriter packetWriter)
         {
             byte connectAcknowledgeFlags = 0x0;
             if (packet.IsSessionPresent)
@@ -82,7 +92,7 @@ namespace MQTTnet.Formatter.V3
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.ConnAck);
         }
 
-        protected override MqttBasePacket DecodeConnAckPacket(MqttPacketBodyReader body)
+        protected override MqttBasePacket DecodeConnAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 

Source/MQTTnet/Formatter/V5/MqttV500DataConverter.cs

@@ -10,6 +10,9 @@ using MQTTnet.Client.Unsubscribing;
 using MQTTnet.Exceptions;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
+using MQTTnet.Server;
+
+using MqttClientSubscribeResult = MQTTnet.Client.Subscribing.MqttClientSubscribeResult;
 
 namespace MQTTnet.Formatter.V5
 {
@@ -33,19 +36,29 @@ namespace MQTTnet.Formatter.V5
                     MessageExpiryInterval = applicationMessage.MessageExpiryInterval,
                     PayloadFormatIndicator = applicationMessage.PayloadFormatIndicator,
                     ResponseTopic = applicationMessage.ResponseTopic,
-                    SubscriptionIdentifier = applicationMessage.SubscriptionIdentifier,
+                    SubscriptionIdentifiers = applicationMessage.SubscriptionIdentifiers,
                     TopicAlias = applicationMessage.TopicAlias
                 }
             };
 
             if (applicationMessage.UserProperties != null)
             {
+                packet.Properties.UserProperties = new List<MqttUserProperty>();
                 packet.Properties.UserProperties.AddRange(applicationMessage.UserProperties);
             }
 
             return packet;
         }
 
+        public MqttPubAckPacket CreatePubAckPacket(MqttPublishPacket publishPacket)
+        {
+            return new MqttPubAckPacket
+            {
+                PacketIdentifier = publishPacket.PacketIdentifier,
+                ReasonCode = MqttPubAckReasonCode.Success
+            };
+        }
+
         public MqttApplicationMessage CreateApplicationMessage(MqttPublishPacket publishPacket)
         {
             return new MqttApplicationMessage
@@ -54,6 +67,13 @@ namespace MQTTnet.Formatter.V5
                 Payload = publishPacket.Payload,
                 QualityOfServiceLevel = publishPacket.QualityOfServiceLevel,
                 Retain = publishPacket.Retain,
+                ResponseTopic = publishPacket.Properties?.ResponseTopic,
+                ContentType = publishPacket.Properties?.ContentType,
+                CorrelationData = publishPacket.Properties?.CorrelationData,
+                MessageExpiryInterval = publishPacket.Properties?.MessageExpiryInterval,
+                SubscriptionIdentifiers = publishPacket.Properties?.SubscriptionIdentifiers,
+                TopicAlias = publishPacket.Properties?.TopicAlias,
+                PayloadFormatIndicator = publishPacket.Properties?.PayloadFormatIndicator,
                 UserProperties = publishPacket.Properties?.UserProperties ?? new List<MqttUserProperty>()
             };
         }
@@ -65,7 +85,23 @@ namespace MQTTnet.Formatter.V5
             return new MqttClientAuthenticateResult
             {
                 IsSessionPresent = connAckPacket.IsSessionPresent,
-                ResultCode = (MqttClientConnectResultCode)connAckPacket.ReasonCode.Value
+                ResultCode = (MqttClientConnectResultCode)connAckPacket.ReasonCode.Value,
+                WildcardSubscriptionAvailable = connAckPacket.Properties?.WildcardSubscriptionAvailable,
+                RetainAvailable = connAckPacket.Properties?.RetainAvailable,
+                AssignedClientIdentifier = connAckPacket.Properties?.AssignedClientIdentifier,
+                AuthenticationMethod = connAckPacket.Properties?.AuthenticationMethod,
+                AuthenticationData = connAckPacket.Properties?.AuthenticationData,
+                MaximumPacketSize = connAckPacket.Properties?.MaximumPacketSize,
+                ReasonString = connAckPacket.Properties?.ReasonString,
+                ReceiveMaximum = connAckPacket.Properties?.ReceiveMaximum,
+                ResponseInformation = connAckPacket.Properties?.ResponseInformation,
+                TopicAliasMaximum = connAckPacket.Properties?.TopicAliasMaximum,
+                ServerReference = connAckPacket.Properties?.ServerReference,
+                ServerKeepAlive = connAckPacket.Properties?.ServerKeepAlive,
+                SessionExpiryInterval = connAckPacket.Properties?.SessionExpiryInterval,
+                SubscriptionIdentifiersAvailable = connAckPacket.Properties?.SubscriptionIdentifiersAvailable,
+                SharedSubscriptionAvailable = connAckPacket.Properties?.SharedSubscriptionAvailable,
+                UserProperties = connAckPacket.Properties?.UserProperties
             };
         }
 
@@ -96,6 +132,22 @@ namespace MQTTnet.Formatter.V5
             };
         }
 
+        public MqttConnAckPacket CreateConnAckPacket(MqttConnectionValidatorContext connectionValidatorContext)
+        {
+            return new MqttConnAckPacket
+            {
+                ReasonCode = connectionValidatorContext.ReasonCode,
+                Properties = new MqttConnAckPacketProperties
+                {
+                    UserProperties = connectionValidatorContext.UserProperties,
+                    AuthenticationMethod = connectionValidatorContext.AuthenticationMethod,
+                    AuthenticationData = connectionValidatorContext.ResponseAuthenticationData,
+                    AssignedClientIdentifier = connectionValidatorContext.AssignedClientIdentifier,
+                    ReasonString = connectionValidatorContext.ReasonString
+                }
+            };
+        }
+
         public MqttClientSubscribeResult CreateClientSubscribeResult(MqttSubscribePacket subscribePacket, MqttSubAckPacket subAckPacket)
         {
             if (subscribePacket == null) throw new ArgumentNullException(nameof(subscribePacket));
@@ -142,7 +194,8 @@ namespace MQTTnet.Formatter.V5
             };
 
             packet.TopicFilters.AddRange(options.TopicFilters);
-            packet.Properties.UserProperties.AddRange(options.UserProperties);
+            packet.Properties.SubscriptionIdentifier = options.SubscriptionIdentifier;
+            packet.Properties.UserProperties = options.UserProperties;
 
             return packet;
         }
@@ -157,7 +210,7 @@ namespace MQTTnet.Formatter.V5
             };
 
             packet.TopicFilters.AddRange(options.TopicFilters);
-            packet.Properties.UserProperties.AddRange(options.UserProperties);
+            packet.Properties.UserProperties = options.UserProperties;
 
             return packet;
         }
@@ -180,13 +233,22 @@ namespace MQTTnet.Formatter.V5
 
         public MqttClientPublishResult CreatePublishResult(MqttPubAckPacket pubAckPacket)
         {
-            var result = new MqttClientPublishResult();
-
-            if (pubAckPacket?.ReasonCode != null)
+            var result = new MqttClientPublishResult
             {
-                result.ReasonCode = (MqttClientPublishReasonCode)pubAckPacket.ReasonCode;
-            }
+                ReasonCode = MqttClientPublishReasonCode.Success,
+                ReasonString = pubAckPacket?.Properties?.ReasonString,
+                UserProperties = pubAckPacket?.Properties?.UserProperties
+            };
 
+            if (pubAckPacket != null)
+            {
+                // QoS 0 has no response. So we treat it as a success always.
+                // Both enums have the same values. So it can be easily converted.
+                 result.ReasonCode = (MqttClientPublishReasonCode)pubAckPacket.ReasonCode;
+
+                 result.PacketIdentifier = pubAckPacket.PacketIdentifier;
+            }
+            
             return result;
         }
 
@@ -200,17 +262,24 @@ namespace MQTTnet.Formatter.V5
                 };
             }
 
+            // The PUBCOMP is the last packet in QoS 2. So we use the results from that instead of PUBREC.
             if (pubCompPacket.ReasonCode == MqttPubCompReasonCode.PacketIdentifierNotFound)
             {
                 return new MqttClientPublishResult
                 {
-                    ReasonCode = MqttClientPublishReasonCode.UnspecifiedError
+                    PacketIdentifier = pubCompPacket.PacketIdentifier,
+                    ReasonCode = MqttClientPublishReasonCode.UnspecifiedError,
+                    ReasonString = pubCompPacket.Properties?.ReasonString,
+                    UserProperties = pubCompPacket.Properties?.UserProperties
                 };
             }
 
             var result = new MqttClientPublishResult
             {
-                ReasonCode = MqttClientPublishReasonCode.Success
+                PacketIdentifier = pubCompPacket.PacketIdentifier,
+                ReasonCode = MqttClientPublishReasonCode.Success,
+                ReasonString = pubCompPacket.Properties?.ReasonString,
+                UserProperties = pubCompPacket.Properties?.UserProperties
             };
 
             if (pubRecPacket.ReasonCode.HasValue)

Source/MQTTnet/Formatter/V5/MqttV500PacketDecoder.cs

@@ -1,5 +1,5 @@
 using System;
-using System.Linq;
+using System.Collections.Generic;
 using MQTTnet.Adapter;
 using MQTTnet.Exceptions;
 using MQTTnet.Packets;
@@ -9,6 +9,10 @@ namespace MQTTnet.Formatter.V5
 {
     public class MqttV500PacketDecoder
     {
+        private static readonly MqttPingReqPacket PingReqPacket = new MqttPingReqPacket();
+
+        private static readonly MqttPingRespPacket PingRespPacket = new MqttPingRespPacket();
+
         public MqttBasePacket Decode(ReceivedMqttPacket receivedMqttPacket)
         {
             if (receivedMqttPacket == null) throw new ArgumentNullException(nameof(receivedMqttPacket));
@@ -41,14 +45,11 @@ namespace MQTTnet.Formatter.V5
             }
         }
 
-        private static MqttBasePacket DecodeConnectPacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeConnectPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
-            var packet = new MqttConnectPacket
-            {
-                Properties = new MqttConnectPacketProperties()
-            };
+            var packet = new MqttConnectPacket();
 
             var protocolName = body.ReadStringWithLengthPrefix();
             var protocolVersion = body.ReadByte();
@@ -83,6 +84,11 @@ namespace MQTTnet.Formatter.V5
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttConnectPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.SessionExpiryInterval)
                 {
                     packet.Properties.SessionExpiryInterval = propertiesReader.ReadSessionExpiryInterval();
@@ -91,10 +97,6 @@ namespace MQTTnet.Formatter.V5
                 {
                     packet.Properties.AuthenticationMethod = propertiesReader.ReadAuthenticationMethod();
                 }
-                else if (propertiesReader.CurrentPropertyId == MqttPropertyId.WillDelayInterval)
-                {
-                    packet.Properties.WillDelayInterval = propertiesReader.ReadWillDelayInterval();
-                }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.AuthenticationData)
                 {
                     packet.Properties.AuthenticationData = propertiesReader.ReadAuthenticationData();
@@ -121,11 +123,16 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
-                    propertiesReader.ThrowInvalidPropertyIdException(typeof(MqttConnAckPacket));
+                    propertiesReader.ThrowInvalidPropertyIdException(typeof(MqttConnectPacket));
                 }
             }
 
@@ -133,8 +140,65 @@ namespace MQTTnet.Formatter.V5
 
             if (packet.WillMessage != null)
             {
+                var willPropertiesReader = new MqttV500PropertiesReader(body);
+
+                while (willPropertiesReader.MoveNext())
+                {
+                    if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.PayloadFormatIndicator)
+                    {
+                        packet.WillMessage.PayloadFormatIndicator = propertiesReader.ReadPayloadFormatIndicator();
+                    }
+                    else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.MessageExpiryInterval)
+                    {
+                        packet.WillMessage.MessageExpiryInterval = propertiesReader.ReadMessageExpiryInterval();
+                    }
+                    else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.TopicAlias)
+                    {
+                        packet.WillMessage.TopicAlias = propertiesReader.ReadTopicAlias();
+                    }
+                    else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.ResponseTopic)
+                    {
+                        packet.WillMessage.ResponseTopic = propertiesReader.ReadResponseTopic();
+                    }
+                    else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.CorrelationData)
+                    {
+                        packet.WillMessage.CorrelationData = propertiesReader.ReadCorrelationData();
+                    }
+                    else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.SubscriptionIdentifier)
+                    {
+                        if (packet.WillMessage.SubscriptionIdentifiers == null)
+                        {
+                            packet.WillMessage.SubscriptionIdentifiers = new List<uint>();
+                        }
+
+                        packet.WillMessage.SubscriptionIdentifiers.Add(propertiesReader.ReadSubscriptionIdentifier());
+                    }
+                    else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.ContentType)
+                    {
+                        packet.WillMessage.ContentType = propertiesReader.ReadContentType();
+                    }
+                    else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.WillDelayInterval)
+                    {
+                        // This is a special case!
+                        packet.Properties.WillDelayInterval = propertiesReader.ReadWillDelayInterval();
+                    }
+                    else if (willPropertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
+                    {
+                        if (packet.WillMessage.UserProperties == null)
+                        {
+                            packet.WillMessage.UserProperties = new List<MqttUserProperty>();
+                        }
+
+                        propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
+                    }
+                    else
+                    {
+                        propertiesReader.ThrowInvalidPropertyIdException(typeof(MqttPublishPacket));
+                    }
+                }
+
                 packet.WillMessage.Topic = body.ReadStringWithLengthPrefix();
-                packet.WillMessage.Payload = body.ReadWithLengthPrefix().ToArray();
+                packet.WillMessage.Payload = body.ReadWithLengthPrefix();
             }
 
             if (usernameFlag)
@@ -144,13 +208,13 @@ namespace MQTTnet.Formatter.V5
 
             if (passwordFlag)
             {
-                packet.Password = body.ReadStringWithLengthPrefix();
+                packet.Password = body.ReadWithLengthPrefix();
             }
 
             return packet;
         }
 
-        private static MqttBasePacket DecodeConnAckPacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeConnAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -159,13 +223,17 @@ namespace MQTTnet.Formatter.V5
             var packet = new MqttConnAckPacket
             {
                 IsSessionPresent = (acknowledgeFlags & 0x1) > 0,
-                ReasonCode = (MqttConnectReasonCode)body.ReadByte(),
-                Properties = new MqttConnAckPacketProperties()
+                ReasonCode = (MqttConnectReasonCode)body.ReadByte()
             };
 
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttConnAckPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.SessionExpiryInterval)
                 {
                     packet.Properties.SessionExpiryInterval = propertiesReader.ReadSessionExpiryInterval();
@@ -186,7 +254,7 @@ namespace MQTTnet.Formatter.V5
                 {
                     packet.Properties.ReceiveMaximum = propertiesReader.ReadReceiveMaximum();
                 }
-                else if (propertiesReader.CurrentPropertyId == MqttPropertyId.AssignedClientIdentifer)
+                else if (propertiesReader.CurrentPropertyId == MqttPropertyId.AssignedClientIdentifier)
                 {
                     packet.Properties.AssignedClientIdentifier = propertiesReader.ReadAssignedClientIdentifier();
                 }
@@ -228,7 +296,12 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -239,19 +312,23 @@ namespace MQTTnet.Formatter.V5
             return packet;
         }
 
-        private static MqttBasePacket DecodeDisconnectPacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeDisconnectPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
             var packet = new MqttDisconnectPacket
             {
-                ReasonCode = (MqttDisconnectReasonCode)body.ReadByte(),
-                Properties = new MqttDisconnectPacketProperties()
+                ReasonCode = (MqttDisconnectReasonCode)body.ReadByte()
             };
 
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttDisconnectPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.SessionExpiryInterval)
                 {
                     packet.Properties.SessionExpiryInterval = propertiesReader.ReadSessionExpiryInterval();
@@ -266,7 +343,12 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -277,26 +359,35 @@ namespace MQTTnet.Formatter.V5
             return packet;
         }
 
-        private static MqttBasePacket DecodeSubscribePacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeSubscribePacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
             var packet = new MqttSubscribePacket
             {
-                PacketIdentifier = body.ReadTwoByteInteger(),
-                Properties = new MqttSubscribePacketProperties()
+                PacketIdentifier = body.ReadTwoByteInteger()
             };
 
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttSubscribePacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.SubscriptionIdentifier)
                 {
                     packet.Properties.SubscriptionIdentifier = propertiesReader.ReadSubscriptionIdentifier();
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -327,26 +418,35 @@ namespace MQTTnet.Formatter.V5
             return packet;
         }
 
-        private static MqttBasePacket DecodeSubAckPacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeSubAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
             var packet = new MqttSubAckPacket
             {
-                PacketIdentifier = body.ReadTwoByteInteger(),
-                Properties = new MqttSubAckPacketProperties()
+                PacketIdentifier = body.ReadTwoByteInteger()
             };
 
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttSubAckPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.ReasonString)
                 {
                     packet.Properties.ReasonString = propertiesReader.ReadReasonString();
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -363,22 +463,31 @@ namespace MQTTnet.Formatter.V5
             return packet;
         }
 
-        private static MqttBasePacket DecodeUnsubscribePacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeUnsubscribePacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
             var packet = new MqttUnsubscribePacket
             {
-                PacketIdentifier = body.ReadTwoByteInteger(),
-                Properties = new MqttUnsubscribePacketProperties()
+                PacketIdentifier = body.ReadTwoByteInteger()
             };
 
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttUnsubscribePacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -394,26 +503,35 @@ namespace MQTTnet.Formatter.V5
             return packet;
         }
 
-        private static MqttBasePacket DecodeUnsubAckPacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeUnsubAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
             var packet = new MqttUnsubAckPacket
             {
-                PacketIdentifier = body.ReadTwoByteInteger(),
-                Properties = new MqttUnsubAckPacketProperties()
+                PacketIdentifier = body.ReadTwoByteInteger()
             };
 
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttUnsubAckPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.ReasonString)
                 {
                     packet.Properties.ReasonString = propertiesReader.ReadReasonString();
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -432,15 +550,15 @@ namespace MQTTnet.Formatter.V5
 
         private static MqttBasePacket DecodePingReqPacket()
         {
-            return new MqttPingReqPacket();
+            return PingReqPacket;
         }
 
         private static MqttBasePacket DecodePingRespPacket()
         {
-            return new MqttPingRespPacket();
+            return PingRespPacket;
         }
 
-        private static MqttBasePacket DecodePublishPacket(byte header, MqttPacketBodyReader body)
+        private static MqttBasePacket DecodePublishPacket(byte header, IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
@@ -453,8 +571,7 @@ namespace MQTTnet.Formatter.V5
                 Topic = body.ReadStringWithLengthPrefix(),
                 Retain = retain,
                 QualityOfServiceLevel = qos,
-                Dup = dup,
-                Properties = new MqttPublishPacketProperties()
+                Dup = dup
             };
 
             if (qos > 0)
@@ -465,6 +582,11 @@ namespace MQTTnet.Formatter.V5
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttPublishPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.PayloadFormatIndicator)
                 {
                     packet.Properties.PayloadFormatIndicator = propertiesReader.ReadPayloadFormatIndicator();
@@ -487,7 +609,12 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.SubscriptionIdentifier)
                 {
-                    packet.Properties.SubscriptionIdentifier = propertiesReader.ReadSubscriptionIdentifier();
+                    if (packet.Properties.SubscriptionIdentifiers == null)
+                    {
+                        packet.Properties.SubscriptionIdentifiers = new List<uint>();
+                    }
+
+                    packet.Properties.SubscriptionIdentifiers.Add(propertiesReader.ReadSubscriptionIdentifier());
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.ContentType)
                 {
@@ -495,7 +622,12 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -503,19 +635,21 @@ namespace MQTTnet.Formatter.V5
                 }
             }
 
-            packet.Payload = body.ReadRemainingData().ToArray();
+            if (!body.EndOfStream)
+            {
+                packet.Payload = body.ReadRemainingData();
+            }
 
             return packet;
         }
 
-        private static MqttBasePacket DecodePubAckPacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodePubAckPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
             var packet = new MqttPubAckPacket
             {
-                PacketIdentifier = body.ReadTwoByteInteger(),
-                Properties = new MqttPubAckPacketProperties()
+                PacketIdentifier = body.ReadTwoByteInteger()
             };
 
             if (body.EndOfStream)
@@ -529,13 +663,23 @@ namespace MQTTnet.Formatter.V5
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttPubAckPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.ReasonString)
                 {
                     packet.Properties.ReasonString = propertiesReader.ReadReasonString();
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -546,14 +690,13 @@ namespace MQTTnet.Formatter.V5
             return packet;
         }
 
-        private static MqttBasePacket DecodePubRecPacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodePubRecPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
             var packet = new MqttPubRecPacket
             {
-                PacketIdentifier = body.ReadTwoByteInteger(),
-                Properties = new MqttPubRecPacketProperties()
+                PacketIdentifier = body.ReadTwoByteInteger()
             };
 
             if (body.EndOfStream)
@@ -567,13 +710,23 @@ namespace MQTTnet.Formatter.V5
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttPubRecPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.ReasonString)
                 {
                     packet.Properties.ReasonString = propertiesReader.ReadReasonString();
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -584,14 +737,13 @@ namespace MQTTnet.Formatter.V5
             return packet;
         }
 
-        private static MqttBasePacket DecodePubRelPacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodePubRelPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
             var packet = new MqttPubRelPacket
             {
-                PacketIdentifier = body.ReadTwoByteInteger(),
-                Properties = new MqttPubRelPacketProperties()
+                PacketIdentifier = body.ReadTwoByteInteger()
             };
 
             if (body.EndOfStream)
@@ -605,13 +757,23 @@ namespace MQTTnet.Formatter.V5
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttPubRelPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.ReasonString)
                 {
                     packet.Properties.ReasonString = propertiesReader.ReadReasonString();
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -622,14 +784,13 @@ namespace MQTTnet.Formatter.V5
             return packet;
         }
 
-        private static MqttBasePacket DecodePubCompPacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodePubCompPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
             var packet = new MqttPubCompPacket
             {
-                PacketIdentifier = body.ReadTwoByteInteger(),
-                Properties = new MqttPubCompPacketProperties()
+                PacketIdentifier = body.ReadTwoByteInteger()
             };
 
             if (body.EndOfStream)
@@ -643,13 +804,23 @@ namespace MQTTnet.Formatter.V5
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttPubCompPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.ReasonString)
                 {
                     packet.Properties.ReasonString = propertiesReader.ReadReasonString();
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -660,14 +831,11 @@ namespace MQTTnet.Formatter.V5
             return packet;
         }
 
-        private static MqttBasePacket DecodeAuthPacket(MqttPacketBodyReader body)
+        private static MqttBasePacket DecodeAuthPacket(IMqttPacketBodyReader body)
         {
             ThrowIfBodyIsEmpty(body);
 
-            var packet = new MqttAuthPacket
-            {
-                Properties = new MqttAuthPacketProperties()
-            };
+            var packet = new MqttAuthPacket();
 
             if (body.EndOfStream)
             {
@@ -680,6 +848,11 @@ namespace MQTTnet.Formatter.V5
             var propertiesReader = new MqttV500PropertiesReader(body);
             while (propertiesReader.MoveNext())
             {
+                if (packet.Properties == null)
+                {
+                    packet.Properties = new MqttAuthPacketProperties();
+                }
+
                 if (propertiesReader.CurrentPropertyId == MqttPropertyId.AuthenticationMethod)
                 {
                     packet.Properties.AuthenticationMethod = propertiesReader.ReadAuthenticationMethod();
@@ -694,7 +867,12 @@ namespace MQTTnet.Formatter.V5
                 }
                 else if (propertiesReader.CurrentPropertyId == MqttPropertyId.UserProperty)
                 {
-                    propertiesReader.FillUserProperties(packet.Properties.UserProperties);
+                    if (packet.Properties.UserProperties == null)
+                    {
+                        packet.Properties.UserProperties = new List<MqttUserProperty>();
+                    }
+
+                    propertiesReader.AddUserPropertyTo(packet.Properties.UserProperties);
                 }
                 else
                 {
@@ -706,7 +884,7 @@ namespace MQTTnet.Formatter.V5
         }
 
         // ReSharper disable once ParameterOnlyUsedForPreconditionCheck.Local
-        private static void ThrowIfBodyIsEmpty(MqttPacketBodyReader body)
+        private static void ThrowIfBodyIsEmpty(IMqttPacketBodyReader body)
         {
             if (body == null || body.Length == 0)
             {

Source/MQTTnet/Formatter/V5/MqttV500PacketEncoder.cs

@@ -8,7 +8,19 @@ namespace MQTTnet.Formatter.V5
 {
     public class MqttV500PacketEncoder
     {
-        private readonly MqttPacketWriter _packetWriter = new MqttPacketWriter();
+        private readonly IMqttPacketWriter _packetWriter;
+
+        public MqttV500PacketEncoder()
+            : this(new MqttPacketWriter())
+        {
+
+        }
+
+        public MqttV500PacketEncoder(IMqttPacketWriter packetWriter)
+        {
+            _packetWriter = packetWriter;
+        }
+
 
         public ArraySegment<byte> Encode(MqttBasePacket packet)
         {
@@ -21,15 +33,15 @@ namespace MQTTnet.Formatter.V5
             var fixedHeader = EncodePacket(packet, _packetWriter);
             var remainingLength = (uint)(_packetWriter.Length - 5);
 
-            var remainingLengthBuffer = MqttPacketWriter.EncodeVariableLengthInteger(remainingLength);
-
-            var headerSize = 1 + remainingLengthBuffer.Count;
+            var remainingLengthSize = MqttPacketWriter.GetLengthOfVariableInteger(remainingLength);
+            
+            var headerSize = 1 + remainingLengthSize;
             var headerOffset = 5 - headerSize;
 
             // Position cursor on correct offset on beginning of array (has leading 0x0)
             _packetWriter.Seek(headerOffset);
             _packetWriter.Write(fixedHeader);
-            _packetWriter.Write(remainingLengthBuffer.Array, remainingLengthBuffer.Offset, remainingLengthBuffer.Count);
+            _packetWriter.WriteVariableLengthInteger(remainingLength);
 
             var buffer = _packetWriter.GetBuffer();
             return new ArraySegment<byte>(buffer, headerOffset, _packetWriter.Length - headerOffset);
@@ -40,7 +52,7 @@ namespace MQTTnet.Formatter.V5
             _packetWriter.FreeBuffer();
         }
 
-        private static byte EncodePacket(MqttBasePacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePacket(MqttBasePacket packet, IMqttPacketWriter packetWriter)
         {
             switch (packet)
             {
@@ -64,7 +76,7 @@ namespace MQTTnet.Formatter.V5
             }
         }
 
-        private static byte EncodeConnectPacket(MqttConnectPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeConnectPacket(MqttConnectPacket packet, IMqttPacketWriter packetWriter)
         {
             if (packet == null) throw new ArgumentNullException(nameof(packet));
             if (packetWriter == null) throw new ArgumentNullException(nameof(packetWriter));
@@ -115,24 +127,38 @@ namespace MQTTnet.Formatter.V5
             var propertiesWriter = new MqttV500PropertiesWriter();
             if (packet.Properties != null)
             {
-                propertiesWriter.WriteWillDelayInterval(packet.Properties.WillDelayInterval);
                 propertiesWriter.WriteSessionExpiryInterval(packet.Properties.SessionExpiryInterval);
                 propertiesWriter.WriteAuthenticationMethod(packet.Properties.AuthenticationMethod);
                 propertiesWriter.WriteAuthenticationData(packet.Properties.AuthenticationData);
                 propertiesWriter.WriteRequestProblemInformation(packet.Properties.RequestProblemInformation);
                 propertiesWriter.WriteRequestResponseInformation(packet.Properties.RequestResponseInformation);
                 propertiesWriter.WriteReceiveMaximum(packet.Properties.ReceiveMaximum);
-                propertiesWriter.WriteTopicAlias(packet.Properties.TopicAliasMaximum);
+                propertiesWriter.WriteTopicAliasMaximum(packet.Properties.TopicAliasMaximum);
                 propertiesWriter.WriteMaximumPacketSize(packet.Properties.MaximumPacketSize);
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            propertiesWriter.WriteToPacket(packetWriter);
+            propertiesWriter.WriteTo(packetWriter);
 
             packetWriter.WriteWithLengthPrefix(packet.ClientId);
-
+            
             if (packet.WillMessage != null)
             {
+                var willPropertiesWriter = new MqttV500PropertiesWriter();
+                willPropertiesWriter.WritePayloadFormatIndicator(packet.WillMessage.PayloadFormatIndicator);
+                willPropertiesWriter.WriteMessageExpiryInterval(packet.WillMessage.MessageExpiryInterval);
+                willPropertiesWriter.WriteTopicAlias(packet.WillMessage.TopicAlias);
+                willPropertiesWriter.WriteResponseTopic(packet.WillMessage.ResponseTopic);
+                willPropertiesWriter.WriteCorrelationData(packet.WillMessage.CorrelationData);
+                willPropertiesWriter.WriteSubscriptionIdentifiers(packet.WillMessage.SubscriptionIdentifiers);
+                willPropertiesWriter.WriteContentType(packet.WillMessage.ContentType);
+                willPropertiesWriter.WriteUserProperties(packet.WillMessage.UserProperties);
+                
+                // This is a special case!
+                willPropertiesWriter.WriteWillDelayInterval(packet.Properties?.WillDelayInterval);
+
+                willPropertiesWriter.WriteTo(packetWriter);
+
                 packetWriter.WriteWithLengthPrefix(packet.WillMessage.Topic);
                 packetWriter.WriteWithLengthPrefix(packet.WillMessage.Payload);
             }
@@ -150,7 +176,7 @@ namespace MQTTnet.Formatter.V5
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Connect);
         }
 
-        private static byte EncodeConnAckPacket(MqttConnAckPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeConnAckPacket(MqttConnAckPacket packet, IMqttPacketWriter packetWriter)
         {
             if (packet == null) throw new ArgumentNullException(nameof(packet));
             if (packetWriter == null) throw new ArgumentNullException(nameof(packetWriter));
@@ -190,12 +216,12 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            propertiesWriter.WriteToPacket(packetWriter);
+            propertiesWriter.WriteTo(packetWriter);
 
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.ConnAck);
         }
 
-        private static byte EncodePublishPacket(MqttPublishPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePublishPacket(MqttPublishPacket packet, IMqttPacketWriter packetWriter)
         {
             if (packet == null) throw new ArgumentNullException(nameof(packet));
             if (packetWriter == null) throw new ArgumentNullException(nameof(packetWriter));
@@ -232,12 +258,12 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteTopicAlias(packet.Properties.TopicAlias);
                 propertiesWriter.WriteResponseTopic(packet.Properties.ResponseTopic);
                 propertiesWriter.WriteCorrelationData(packet.Properties.CorrelationData);
-                propertiesWriter.WriteSubscriptionIdentifier(packet.Properties.SubscriptionIdentifier);
+                propertiesWriter.WriteSubscriptionIdentifiers(packet.Properties.SubscriptionIdentifiers);
                 propertiesWriter.WriteContentType(packet.Properties.ContentType);
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            propertiesWriter.WriteToPacket(packetWriter);
+            propertiesWriter.WriteTo(packetWriter);
 
             if (packet.Payload?.Length > 0)
             {
@@ -261,7 +287,7 @@ namespace MQTTnet.Formatter.V5
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Publish, fixedHeader);
         }
 
-        private static byte EncodePubAckPacket(MqttPubAckPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePubAckPacket(MqttPubAckPacket packet, IMqttPacketWriter packetWriter)
         {
             if (packet == null) throw new ArgumentNullException(nameof(packet));
             if (packetWriter == null) throw new ArgumentNullException(nameof(packetWriter));
@@ -273,7 +299,7 @@ namespace MQTTnet.Formatter.V5
 
             if (!packet.ReasonCode.HasValue)
             {
-                throw new MqttProtocolViolationException("PubAck packet must contain a connect reason.");
+                throw new MqttProtocolViolationException("PubAck packet must contain a reason code.");
             }
 
             packetWriter.Write(packet.PacketIdentifier.Value);
@@ -288,13 +314,13 @@ namespace MQTTnet.Formatter.V5
             if (packetWriter.Length > 0 || packet.ReasonCode.Value != MqttPubAckReasonCode.Success)
             {
                 packetWriter.Write((byte)packet.ReasonCode.Value);
-                propertiesWriter.WriteToPacket(packetWriter);
+                propertiesWriter.WriteTo(packetWriter);
             }
             
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubAck);
         }
 
-        private static byte EncodePubRecPacket(MqttPubRecPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePubRecPacket(MqttPubRecPacket packet, IMqttPacketWriter packetWriter)
         {
             ThrowIfPacketIdentifierIsInvalid(packet);
 
@@ -316,13 +342,13 @@ namespace MQTTnet.Formatter.V5
             if (packetWriter.Length > 0 || packet.ReasonCode.Value != MqttPubRecReasonCode.Success)
             {
                 packetWriter.Write((byte)packet.ReasonCode.Value);
-                propertiesWriter.WriteToPacket(packetWriter);
+                propertiesWriter.WriteTo(packetWriter);
             }
 
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubRec);
         }
 
-        private static byte EncodePubRelPacket(MqttPubRelPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePubRelPacket(MqttPubRelPacket packet, IMqttPacketWriter packetWriter)
         {
             ThrowIfPacketIdentifierIsInvalid(packet);
 
@@ -331,9 +357,6 @@ namespace MQTTnet.Formatter.V5
                 ThrowReasonCodeNotSetException();
             }
 
-            packetWriter.Write(packet.PacketIdentifier.Value);
-            packetWriter.Write((byte)packet.ReasonCode.Value);
-
             var propertiesWriter = new MqttV500PropertiesWriter();
             if (packet.Properties != null)
             {
@@ -341,16 +364,18 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            if (packetWriter.Length > 0 || packet.ReasonCode.Value != MqttPubRelReasonCode.Success)
+            packetWriter.Write(packet.PacketIdentifier.Value);
+            
+            if (propertiesWriter.Length > 0 || packet.ReasonCode.Value != MqttPubRelReasonCode.Success)
             {
                 packetWriter.Write((byte)packet.ReasonCode.Value);
-                propertiesWriter.WriteToPacket(packetWriter);
+                propertiesWriter.WriteTo(packetWriter);
             }
 
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubRel, 0x02);
         }
 
-        private static byte EncodePubCompPacket(MqttPubCompPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodePubCompPacket(MqttPubCompPacket packet, IMqttPacketWriter packetWriter)
         {
             ThrowIfPacketIdentifierIsInvalid(packet);
 
@@ -360,8 +385,7 @@ namespace MQTTnet.Formatter.V5
             }
 
             packetWriter.Write(packet.PacketIdentifier.Value);
-            packetWriter.Write((byte)packet.ReasonCode.Value);
-
+            
             var propertiesWriter = new MqttV500PropertiesWriter();
             if (packet.Properties != null)
             {
@@ -369,18 +393,18 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            if (packetWriter.Length > 0 || packet.ReasonCode.Value != MqttPubCompReasonCode.Success)
+            if (propertiesWriter.Length > 0 || packet.ReasonCode.Value != MqttPubCompReasonCode.Success)
             {
                 packetWriter.Write((byte)packet.ReasonCode.Value);
-                propertiesWriter.WriteToPacket(packetWriter);
+                propertiesWriter.WriteTo(packetWriter);
             }
 
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubComp);
         }
 
-        private static byte EncodeSubscribePacket(MqttSubscribePacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeSubscribePacket(MqttSubscribePacket packet, IMqttPacketWriter packetWriter)
         {
-            if (!packet.TopicFilters.Any()) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.8.3-3].");
+            if (packet.TopicFilters?.Any() != true) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.8.3-3].");
 
             ThrowIfPacketIdentifierIsInvalid(packet);
 
@@ -393,7 +417,7 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            propertiesWriter.WriteToPacket(packetWriter);
+            propertiesWriter.WriteTo(packetWriter);
 
             if (packet.TopicFilters?.Count > 0)
             {
@@ -425,14 +449,11 @@ namespace MQTTnet.Formatter.V5
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Subscribe, 0x02);
         }
 
-        private static byte EncodeSubAckPacket(MqttSubAckPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeSubAckPacket(MqttSubAckPacket packet, IMqttPacketWriter packetWriter)
         {
-            ThrowIfPacketIdentifierIsInvalid(packet);
+            if (packet.ReasonCodes?.Any() != true) throw new MqttProtocolViolationException("At least one reason code must be set[MQTT - 3.8.3 - 3].");
 
-            if (packet.ReasonCodes == null || !packet.ReasonCodes.Any())
-            {
-                throw new MqttProtocolViolationException("At least one reason code must be set[MQTT - 3.8.3 - 3].");
-            }
+            ThrowIfPacketIdentifierIsInvalid(packet);
 
             packetWriter.Write(packet.PacketIdentifier.Value);
 
@@ -443,7 +464,7 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            propertiesWriter.WriteToPacket(packetWriter);
+            propertiesWriter.WriteTo(packetWriter);
 
             foreach (var reasonCode in packet.ReasonCodes)
             {
@@ -453,9 +474,9 @@ namespace MQTTnet.Formatter.V5
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.SubAck);
         }
 
-        private static byte EncodeUnsubscribePacket(MqttUnsubscribePacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeUnsubscribePacket(MqttUnsubscribePacket packet, IMqttPacketWriter packetWriter)
         {
-            if (!packet.TopicFilters.Any()) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.10.3-2].");
+            if (packet.TopicFilters?.Any() != true) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.10.3-2].");
 
             ThrowIfPacketIdentifierIsInvalid(packet);
 
@@ -467,7 +488,7 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            propertiesWriter.WriteToPacket(packetWriter);
+            propertiesWriter.WriteTo(packetWriter);
 
             foreach (var topicFilter in packet.TopicFilters)
             {
@@ -477,15 +498,12 @@ namespace MQTTnet.Formatter.V5
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Unsubscibe, 0x02);
         }
 
-        private static byte EncodeUnsubAckPacket(MqttUnsubAckPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeUnsubAckPacket(MqttUnsubAckPacket packet, IMqttPacketWriter packetWriter)
         {
+            if (packet.ReasonCodes?.Any() != true) throw new MqttProtocolViolationException("At least one reason code must be set[MQTT - 3.8.3 - 3].");
+
             ThrowIfPacketIdentifierIsInvalid(packet);
-
-            if (packet.ReasonCodes == null || !packet.ReasonCodes.Any())
-            {
-                throw new MqttProtocolViolationException("At least one reason code must be set[MQTT - 3.8.3 - 3].");
-            }
-
+            
             packetWriter.Write(packet.PacketIdentifier.Value);
 
             var propertiesWriter = new MqttV500PropertiesWriter();
@@ -495,7 +513,7 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            propertiesWriter.WriteToPacket(packetWriter);
+            propertiesWriter.WriteTo(packetWriter);
 
             foreach (var reasonCode in packet.ReasonCodes)
             {
@@ -505,7 +523,7 @@ namespace MQTTnet.Formatter.V5
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.UnsubAck);
         }
 
-        private static byte EncodeDisconnectPacket(MqttDisconnectPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeDisconnectPacket(MqttDisconnectPacket packet, IMqttPacketWriter packetWriter)
         {
             if (!packet.ReasonCode.HasValue)
             {
@@ -523,7 +541,7 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            propertiesWriter.WriteToPacket(packetWriter);
+            propertiesWriter.WriteTo(packetWriter);
 
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Disconnect);
         }
@@ -538,7 +556,7 @@ namespace MQTTnet.Formatter.V5
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PingResp);
         }
 
-        private static byte EncodeAuthPacket(MqttAuthPacket packet, MqttPacketWriter packetWriter)
+        private static byte EncodeAuthPacket(MqttAuthPacket packet, IMqttPacketWriter packetWriter)
         {
             packetWriter.Write((byte)packet.ReasonCode);
 
@@ -551,7 +569,7 @@ namespace MQTTnet.Formatter.V5
                 propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
             }
 
-            propertiesWriter.WriteToPacket(packetWriter);
+            propertiesWriter.WriteTo(packetWriter);
 
             return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Auth);
         }

Source/MQTTnet/Formatter/V5/MqttV500PacketFormatter.cs

@@ -6,9 +6,19 @@ namespace MQTTnet.Formatter.V5
 {
     public class MqttV500PacketFormatter : IMqttPacketFormatter
     {
-        private readonly MqttV500PacketEncoder _encoder = new MqttV500PacketEncoder();
+        private readonly MqttV500PacketEncoder _encoder;
         private readonly MqttV500PacketDecoder _decoder = new MqttV500PacketDecoder();
 
+        public MqttV500PacketFormatter()
+        {
+            _encoder = new MqttV500PacketEncoder();
+        }
+
+        public MqttV500PacketFormatter(IMqttPacketWriter writer)
+        {
+            _encoder = new MqttV500PacketEncoder(writer);
+        }
+
         public IMqttDataConverter DataConverter { get; } = new MqttV500DataConverter();
         
         public ArraySegment<byte> Encode(MqttBasePacket mqttPacket)