Added reference to SparkplugNet.

Update MQTTnet.nuspec
Added code documentation hint.
2026-10-15 08:33:01 +08:00 · 2021-01-31 17:35:39 +01:00 · 2021-01-31 11:34:27 +01:00 · 2021-01-31 11:33:13 +01:00 · 2021-01-30 15:39:04 +01:00 · 2021-01-30 13:24:24 +01:00
300 changed files with 6704 additions and 3917 deletions
@@ -1,5 +1,84 @@
-[*.cs]
+[*.cs]


 # CA1031: Do not catch general exception types
-dotnet_diagnostic.CA1031.severity = none
+
+# Microsoft .NET properties
+csharp_new_line_before_members_in_object_initializers = false
+csharp_preferred_modifier_order = public, private, protected, internal, new, abstract, virtual, sealed, override, static, readonly, extern, unsafe, volatile, async:suggestion
+csharp_style_var_elsewhere = true:suggestion
+csharp_style_var_for_built_in_types = true:suggestion
+csharp_style_var_when_type_is_apparent = true:suggestion
+dotnet_naming_rule.constants_rule.severity = warning
+dotnet_naming_rule.constants_rule.style = upper_camel_case_style
+dotnet_naming_rule.constants_rule.symbols = constants_symbols
+dotnet_naming_rule.public_fields_rule.severity = warning
+dotnet_naming_rule.public_fields_rule.style = lower_camel_case_style
+dotnet_naming_rule.public_fields_rule.symbols = public_fields_symbols
+dotnet_naming_rule.static_readonly_rule.severity = warning
+dotnet_naming_rule.static_readonly_rule.style = upper_camel_case_style
+dotnet_naming_rule.static_readonly_rule.symbols = static_readonly_symbols
+dotnet_naming_style.lower_camel_case_style.capitalization = camel_case
+dotnet_naming_style.lower_camel_case_style.required_prefix = _
+dotnet_naming_style.upper_camel_case_style.capitalization = pascal_case
+dotnet_naming_symbols.constants_symbols.applicable_accessibilities = public,internal,protected,protected_internal,private_protected
+dotnet_naming_symbols.constants_symbols.applicable_kinds = field
+dotnet_naming_symbols.constants_symbols.required_modifiers = const
+dotnet_naming_symbols.public_fields_symbols.applicable_accessibilities = public,internal,protected,protected_internal,private_protected
+dotnet_naming_symbols.public_fields_symbols.applicable_kinds = field
+dotnet_naming_symbols.static_readonly_symbols.applicable_accessibilities = public,internal,protected,protected_internal,private_protected
+dotnet_naming_symbols.static_readonly_symbols.applicable_kinds = field
+dotnet_naming_symbols.static_readonly_symbols.required_modifiers = static,readonly
+dotnet_style_parentheses_in_arithmetic_binary_operators = never_if_unnecessary:none
+dotnet_style_parentheses_in_other_binary_operators = never_if_unnecessary:none
+dotnet_style_parentheses_in_relational_binary_operators = never_if_unnecessary:none
+dotnet_style_predefined_type_for_locals_parameters_members = true:suggestion
+dotnet_style_predefined_type_for_member_access = true:suggestion
+dotnet_style_qualification_for_event = false:suggestion
+dotnet_style_qualification_for_field = false:suggestion
+dotnet_style_qualification_for_method = false:suggestion
+dotnet_style_qualification_for_property = false:suggestion
+
+# ReSharper properties
+resharper_autodetect_indent_settings = true
+resharper_default_private_modifier = implicit
+resharper_place_accessorholder_attribute_on_same_line = false
+resharper_use_indent_from_vs = false
+
+# ReSharper inspection severities
+resharper_arrange_redundant_parentheses_highlighting = hint
+resharper_arrange_this_qualifier_highlighting = hint
+resharper_built_in_type_reference_style_for_member_access_highlighting = hint
+resharper_built_in_type_reference_style_highlighting = hint
+resharper_redundant_base_qualifier_highlighting = warning
+resharper_suggest_var_or_type_built_in_types_highlighting = hint
+resharper_suggest_var_or_type_elsewhere_highlighting = hint
+resharper_suggest_var_or_type_simple_types_highlighting = hint
+resharper_web_config_module_not_resolved_highlighting = warning
+resharper_web_config_type_not_resolved_highlighting = warning
+resharper_web_config_wrong_module_highlighting = warning
+
+[*]
+charset = utf-8
+end_of_line = crlf
+trim_trailing_whitespace = false
+insert_final_newline = false
+indent_style = space
+indent_size = 4
+
+[{*.har,*.inputactions,*.jsb2,*.jsb3,*.json,.babelrc,.eslintrc,.stylelintrc,bowerrc,jest.config}]
+indent_style = space
+indent_size = 2
+
+[{*.yaml,*.yml}]
+indent_style = space
+indent_size = 2
+
+[{tsconfig.app.json,tsconfig.e2e.json,tsconfig.json,tsconfig.lib.json,tsconfig.spec.json}]
+indent_style = space
+indent_size = 2
+
+[*.{appxmanifest,asax,ascx,aspx,axaml,build,cg,cginc,compute,cs,cshtml,dtd,hlsl,hlsli,hlslinc,master,nuspec,paml,razor,resw,resx,shader,skin,usf,ush,vb,xaml,xamlx,xoml,xsd}]
+indent_style = space
+indent_size = 4
+tab_width = 4
@@ -13,16 +13,20 @@
    <description>This is a support library to integrate MQTTnet into AspNetCore.</description>
    <releaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</releaseNotes>
    <copyright>Copyright Christian Kratky 2016-2020</copyright>
-    <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags>
+    <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 Blazor</tags>
    <dependencies>
      <group targetFramework="netstandard2.0">
        <dependency id="MQTTnet" version="$nugetVersion" />
        <dependency id="Microsoft.AspNetCore.Http.Connections" version="1.0.0"  />
      </group>
-      
+
      <group targetFramework="netcoreapp3.1">
        <dependency id="MQTTnet" version="$nugetVersion" />
      </group>
+
+      <group targetFramework="net5.0">
+        <dependency id="MQTTnet" version="$nugetVersion" />
+      </group>
    </dependencies>
  </metadata>

@@ -33,10 +37,13 @@
    <!-- Images -->
    <file src="..\Images\Logo_128x128.png" target="images\" />

+    <!-- .NET 5.0 -->
+    <file src="..\Source\MQTTnet.AspNetCore\bin\Release\net5.0\MQTTnet.*" target="lib\net5.0\" />
+
    <!-- .NET Standard 2.0 -->
-    <file src="..\Source\MQTTnet.AspNetCore\bin\Release\netstandard2.0\MQTTnet.AspNetCore.*" target="lib\netstandard2.0\"/>
-    
+    <file src="..\Source\MQTTnet.AspNetCore\bin\Release\netstandard2.0\MQTTnet.AspNetCore.*" target="lib\netstandard2.0\" />
+
    <!-- .NET Core App 3.1 -->
-    <file src="..\Source\MQTTnet.AspNetCore\bin\Release\netcoreapp3.1\MQTTnet.AspNetCore.*" target="lib\netcoreapp3.1\"/>
+    <file src="..\Source\MQTTnet.AspNetCore\bin\Release\netcoreapp3.1\MQTTnet.AspNetCore.*" target="lib\netcoreapp3.1\" />
  </files>
 </package>
@@ -13,7 +13,7 @@
    <description>This is an extension library which provides a managed MQTT client with additional features using MQTTnet.</description>
    <releaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</releaseNotes>
    <copyright>Copyright Christian Kratky 2016-2020</copyright>
-    <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
+    <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 Blazor</tags>
    <dependencies>
      <dependency id="MQTTnet" version="$nugetVersion" />
    </dependencies>
@@ -26,20 +26,23 @@
    <!-- Images -->
    <file src="..\Images\Logo_128x128.png" target="images\" />

+    <!-- .NET 5.0 -->
+    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\net5.0\MQTTnet.*" target="lib\net5.0\" />
+
    <!-- .NET Standard 1.3 -->
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard1.3\MQTTnet.Extensions.ManagedClient.*" target="lib\netstandard1.3\"/>
+    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard1.3\MQTTnet.Extensions.ManagedClient.*" target="lib\netstandard1.3\" />

    <!-- .NET Standard 2.0 -->
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\netstandard2.0\"/>
+    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.0\MQTTnet.Extensions.ManagedClient.*" target="lib\netstandard2.0\" />

    <!-- Universal Windows -->
-    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\uap10.0\MQTTnet.Extensions.ManagedClient.*" target="lib\uap10.0\"/>
+    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\uap10.0\MQTTnet.Extensions.ManagedClient.*" target="lib\uap10.0\" />

    <!-- .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\net452\MQTTnet.Extensions.ManagedClient.*" target="lib\net452\" />

    <!-- .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\"/>
+    <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>
@@ -13,7 +13,7 @@
    <description>This is an extension library which allows executing synchronous device calls including a response using MQTTnet.</description>
    <releaseNotes>For release notes please go to MQTTnet release notes (https://www.nuget.org/packages/MQTTnet/).</releaseNotes>
    <copyright>Copyright Christian Kratky 2016-2020</copyright>
-    <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
+    <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 Blazor</tags>
    <dependencies>
      <dependency id="MQTTnet" version="$nugetVersion" />
    </dependencies>
@@ -26,20 +26,23 @@
    <!-- Images -->
    <file src="..\Images\Logo_128x128.png" target="images\" />

+    <!-- .NET 5.0 -->
+    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\net5.0\MQTTnet.*" target="lib\net5.0\" />
+
    <!-- .NET Standard 1.3 -->
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard1.3\MQTTnet.Extensions.Rpc.*" target="lib\netstandard1.3\"/>
+    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard1.3\MQTTnet.Extensions.Rpc.*" target="lib\netstandard1.3\" />

    <!-- .NET Standard 2.0 -->
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\netstandard2.0\"/>
+    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.0\MQTTnet.Extensions.Rpc.*" target="lib\netstandard2.0\" />

    <!-- Universal Windows -->
-    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\uap10.0\MQTTnet.Extensions.Rpc.*" target="lib\uap10.0\"/>
+    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\uap10.0\MQTTnet.Extensions.Rpc.*" target="lib\uap10.0\" />

    <!-- .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\net452\MQTTnet.Extensions.Rpc.*" target="lib\net452\" />

    <!-- .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\"/>
+    <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>
@@ -13,7 +13,7 @@
    <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 2016-2020</copyright>
-    <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
+    <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 Blazor</tags>
    <dependencies>
    <group targetFramework="netstandard1.3">
        <dependency id="MQTTnet" version="$nugetVersion" />
@@ -41,20 +41,23 @@
    <!-- Images -->
    <file src="..\Images\Logo_128x128.png" target="images\" />

+    <!-- .NET 5.0 -->
+    <file src="..\Source\MQTTnet.Extensions.WebSocket4Net\bin\Release\net5.0\MQTTnet.*" target="lib\net5.0\" />
+
    <!-- .NET Standard 1.3 -->
-    <file src="..\Source\MQTTnet.Extensions.WebSocket4Net\bin\Release\netstandard1.3\MQTTnet.Extensions.WebSocket4Net.*" target="lib\netstandard1.3\"/>
+    <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\"/>
+    <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\"/>
+    <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\"/>
+    <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\"/>
+    <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>
@@ -12,31 +12,35 @@
    <requireLicenseAcceptance>true</requireLicenseAcceptance>
    <description>MQTTnet is a high performance .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker) and supports v3.1.0, v3.1.1 and v5.0.0 of the MQTT protocol.</description>
    <releaseNotes>
-* [Core] Improved logger performance (BREAKING CHANGE!).
-* [Core] Renamed some topic filter relevant classes (BREAKING CHANGE!).
-* [Core] Improved task management for UWP connections (thanks to @xgstation).
-* [Core] Fixed broken logger which decreases overall performance.
-* [Core] Fixed issue in closed socket detection (fixes high CPU load issue).
-* [Client] Added method to trigger PING/PONG manually (connection check etc.).
-* [Client] Added support for certificate validation callback when using Web Sockets (requires netstandard2.1+).
-* [Client] Fixed a memory leak when web socket based connections trying to reconnect with an offline server.
-* [Client] Fixed a memory leak when TCP based connections trying to reconnect with an offline server.
-* [Client] Fixed an issue when connecting to an invalid host (format).
-* [Client] Added support for user properties in CONNECT packet.
-* [Client] Removed _KeepAliveSendInterval_ and improved keep alive handling (BREAKING CHANGE!).
-* [ManagedClient] Added method to trigger PING/PONG manually (connection check etc.).
-* [MQTTnet.AspNetCore] improved compatibility with AspNetCore 3.1.
-* [MQTTnet.AspNetCore] Fixed several packaging issues with the Nuget package.
-* [MQTTnet.Server] Fixed wrong version output.
+* [Core] Added .NET 5.0 TFMs (thanks to @StefanOssendorf, @JanEggers).
+* [Core] Added support for TLS 1.3 (requires .NET Core 3.1+) (thanks to @Dvergatal).
+* [Core] Added support for _MaximumQoS_ transmit when using MQTTv5 (thanks to @nayato).
+* [Core] Aligned the format of some log messages.
+* [Client] Fixed an issue with connection state detection (thanks to @tobiasfrick).
+* [Client] Fixed an issue when receiving partial QoS 2 packets after a reconnect.
+* [Client] Added new API for raw packet inspection.
+* [ManagedClient] Removed _AutoReconnect_ since this does no longer work (BREAKING CHANGE!).
+* [RpcClient] Moved the RPC topic validation to the topic generation strategy.
+* [RcpClient] Added interface for _MqttRpcClient_.
+* [Server] Reduced async tasks count by moving dedicated keep alive tasks per connection to shared one.
+* [Server] Session takeover and keep alive timeout are now properly set in DISCONNECT packet.
+* [Server] Fixed bug in PubRel packet generation (MQTTv5 only).
+* [Server] Improved message processing performance (+ ~5%).
+* [Server] Fix wrong usage of client session items for undelivered messages.
+* [Server] Allow to respond with a reason code in PUBACK/PUBREC (thanks to @muneebmajeed).
+* [Server] Fixed topic filter comparer on edge cases, e.g. "foo/" matching "foo/#" (thanks to @dagophil).
+* [Core] Added code documentation.
+
+Git commit: $gitCommit
    </releaseNotes>
    <copyright>Copyright Christian Kratky 2016-2020</copyright>
-    <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
+    <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 Blazor</tags>
    <dependencies>
      <group targetFramework="netstandard1.3">
        <dependency id="NETStandard.Library" version="1.3.0" />
        <dependency id="System.Net.Security" version="4.3.2" />
        <dependency id="System.Net.WebSockets" version="4.3.0" />
-        <dependency id="System.Net.WebSockets.Client" version="4.3.2" />      
+        <dependency id="System.Net.WebSockets.Client" version="4.3.2" />
      </group>
      <group targetFramework="netstandard2.0">
        <dependency id="NETStandard.Library" version="2.0.0" />
@@ -50,6 +54,12 @@
        <dependency id="System.Net.WebSockets" version="4.3.0" />
        <dependency id="System.Net.WebSockets.Client" version="4.3.2" />
      </group>
+      <group targetFramework="netcoreapp3.1">
+        <dependency id="NETStandard.Library" version="2.0.0" />
+        <dependency id="System.Net.Security" version="4.3.2" />
+        <dependency id="System.Net.WebSockets" version="4.3.0" />
+        <dependency id="System.Net.WebSockets.Client" version="4.3.2" />
+      </group>
      <group targetFramework="uap10.0">
        <dependency id="Microsoft.NETCore.UniversalWindowsPlatform" version="6.2.10" />
      </group>
@@ -63,23 +73,29 @@
    <!-- Images -->
    <file src="..\Images\Logo_128x128.png" target="images\" />

+    <!-- .NET 5.0 -->
+    <file src="..\Source\MQTTnet\bin\Release\net5.0\MQTTnet.*" target="lib\net5.0\" />
+
    <!-- .NET Standard 1.3 -->
-    <file src="..\Source\MQTTnet\bin\Release\netstandard1.3\MQTTnet.*" target="lib\netstandard1.3\"/>
-    
+    <file src="..\Source\MQTTnet\bin\Release\netstandard1.3\MQTTnet.*" target="lib\netstandard1.3\" />
+
    <!-- .NET Standard 2.0 -->
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\netstandard2.0\"/>
+    <file src="..\Source\MQTTnet\bin\Release\netstandard2.0\MQTTnet.*" target="lib\netstandard2.0\" />

    <!-- .NET Standard 2.1 -->
-    <file src="..\Source\MQTTnet\bin\Release\netstandard2.1\MQTTnet.*" target="lib\netstandard2.1\"/>
+    <file src="..\Source\MQTTnet\bin\Release\netstandard2.1\MQTTnet.*" target="lib\netstandard2.1\" />
+
+    <!-- .NET Standard 3.1 -->
+    <file src="..\Source\MQTTnet\bin\Release\netcoreapp3.1\MQTTnet.*" target="lib\netcoreapp3.1\" />

    <!-- Universal Windows -->
-    <file src="..\Source\MQTTnet\bin\Release\uap10.0\MQTTnet.*" target="lib\uap10.0\"/>
+    <file src="..\Source\MQTTnet\bin\Release\uap10.0\MQTTnet.*" target="lib\uap10.0\" />

    <!-- .NET Framework -->
-    <file src="..\Source\MQTTnet\bin\Release\net452\MQTTnet.*" target="lib\net452\"/>
+    <file src="..\Source\MQTTnet\bin\Release\net452\MQTTnet.*" target="lib\net452\" />

    <!-- .NET Framework 4.6.0 will use binaries from 4.5.2. -->
-    <file src="..\Source\MQTTnet\bin\Release\net461\MQTTnet.*" target="lib\net461\"/>
+    <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>
@@ -29,6 +29,7 @@ vstest.console.exe ..\Tests\MQTTnet.AspNetCore.Tests\bin\Release\netcoreapp3.1\M
 &$msbuild ..\Source\MQTTnet\MQTTnet.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard1.3" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet\MQTTnet.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"
 &$msbuild ..\Source\MQTTnet\MQTTnet.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.1" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
+&$msbuild ..\Source\MQTTnet\MQTTnet.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netcoreapp3.1" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet\MQTTnet.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="uap10.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"

 # Build the ASP.NET Core 2.0 extension
@@ -63,6 +64,10 @@ vstest.console.exe ..\Tests\MQTTnet.AspNetCore.Tests\bin\Release\netcoreapp3.1\M

 Remove-Item .\NuGet -Force -Recurse -ErrorAction SilentlyContinue

+$gitCommit = git log -1 --format=%h
+
+Copy-Item MQTTnet.nuspec -Destination MQTTnet.nuspec.old -Force
+(Get-Content MQTTnet.nuspec) -replace '\$gitCommit', $gitCommit | Set-Content MQTTnet.nuspec
 Copy-Item MQTTnet.AspNetCore.nuspec -Destination MQTTnet.AspNetCore.nuspec.old -Force
 (Get-Content MQTTnet.AspNetCore.nuspec) -replace '\$nugetVersion', $nugetVersion | Set-Content MQTTnet.AspNetCore.nuspec
 Copy-Item MQTTnet.Extensions.Rpc.nuspec -Destination MQTTnet.Extensions.Rpc.nuspec.old -Force
@@ -79,6 +84,7 @@ New-Item -ItemType Directory -Force -Path .\NuGet
 .\nuget.exe pack MQTTnet.Extensions.ManagedClient.nuspec -Verbosity detailed -Symbols -SymbolPackageFormat snupkg -OutputDir "NuGet" -Version $nugetVersion
 .\nuget.exe pack MQTTnet.Extensions.WebSocket4Net.nuspec -Verbosity detailed -Symbols -SymbolPackageFormat snupkg -OutputDir "NuGet" -Version $nugetVersion

+Move-Item MQTTnet.nuspec.old -Destination MQTTnet.nuspec -Force
 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
@@ -89,7 +95,7 @@ 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
+&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion --framework net5.0

 $source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\publish"
 $destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Portable-v$nugetVersion.zip"
@@ -100,7 +106,7 @@ If(Test-path $destination) {Remove-item $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 
+&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion --self-contained --runtime linux-x64 --framework net5.0

 $source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\linux-x64\publish"
 $destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Linux-x64-v$nugetVersion.zip"
@@ -111,7 +117,7 @@ If(Test-path $destination) {Remove-item $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 
+&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion --self-contained --runtime linux-arm --framework net5.0

 $source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\linux-ARM\publish"
 $destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Linux-ARM-v$nugetVersion.zip"
@@ -122,7 +128,7 @@ If(Test-path $destination) {Remove-item $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
+&dotnet publish ..\Source\MQTTnet.Server\MQTTnet.Server.csproj --configuration Release /p:FileVersion=$assemblyVersion /p:Version=$nugetVersion --self-contained --runtime win-x64 --framework net5.0

 $source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\win-x64\publish"
 $destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Windows-x64-v$nugetVersion.zip"
@@ -9,8 +9,6 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Tests", "Tests", "{9248C2E1
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Source", "Source", "{32A630A7-2598-41D7-B625-204CD906F5FB}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MQTTnet.TestApp.UniversalWindows", "Tests\MQTTnet.TestApp.UniversalWindows\MQTTnet.TestApp.UniversalWindows.csproj", "{FF1F72D6-9524-4422-9497-3CC0002216ED}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet", "Source\MQTTnet\MQTTnet.csproj", "{3587E506-55A2-4EB3-99C7-DC01E42D25D2}"
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Build", "Build", "{67C28AC1-BC3A-420A-BE9C-FA2401431CF9}"
@@ -55,6 +53,14 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Extensions.WebSocke
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Apps", "Apps", "{A56E3128-1639-4F31-873A-325E14BB6295}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Blazor", "Blazor", "{61B165A0-5AA8-4E04-A53D-A22A84AA6EB7}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Test.BlazorApp.Server", "Tests\MQTTnet.Test.BlazorApp\Server\MQTTnet.Test.BlazorApp.Server.csproj", "{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Test.BlazorApp.Client", "Tests\MQTTnet.Test.BlazorApp\Client\MQTTnet.Test.BlazorApp.Client.csproj", "{D260D63D-7902-4C55-9665-84C5CACBBB24}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MQTTnet.Test.BlazorApp.Shared", "Tests\MQTTnet.Test.BlazorApp\Shared\MQTTnet.Test.BlazorApp.Shared.csproj", "{DDB069BA-6E1A-48C7-B374-5D903B553CAD}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -83,29 +89,6 @@ Global
 		{A7FF0C91-25DE-4BA6-B39E-F54E8DADF1CC}.Release|x64.Build.0 = Release|Any CPU
 		{A7FF0C91-25DE-4BA6-B39E-F54E8DADF1CC}.Release|x86.ActiveCfg = Release|Any CPU
 		{A7FF0C91-25DE-4BA6-B39E-F54E8DADF1CC}.Release|x86.Build.0 = Release|Any CPU
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|Any CPU.Deploy.0 = Debug|Any CPU
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|ARM.ActiveCfg = Debug|ARM
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|ARM.Build.0 = Debug|ARM
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|ARM.Deploy.0 = Debug|ARM
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|x64.ActiveCfg = Debug|x64
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|x64.Build.0 = Debug|x64
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|x64.Deploy.0 = Debug|x64
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|x86.ActiveCfg = Debug|x86
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|x86.Build.0 = Debug|x86
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Debug|x86.Deploy.0 = Debug|x86
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|Any CPU.Build.0 = Release|Any CPU
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|ARM.ActiveCfg = Release|ARM
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|ARM.Build.0 = Release|ARM
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|ARM.Deploy.0 = Release|ARM
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|x64.ActiveCfg = Release|x64
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|x64.Build.0 = Release|x64
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|x64.Deploy.0 = Release|x64
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|x86.ActiveCfg = Release|x86
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|x86.Build.0 = Release|x86
-		{FF1F72D6-9524-4422-9497-3CC0002216ED}.Release|x86.Deploy.0 = Release|x86
 		{3587E506-55A2-4EB3-99C7-DC01E42D25D2}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{3587E506-55A2-4EB3-99C7-DC01E42D25D2}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{3587E506-55A2-4EB3-99C7-DC01E42D25D2}.Debug|ARM.ActiveCfg = Debug|Any CPU
@@ -266,13 +249,60 @@ Global
 		{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
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Debug|ARM.ActiveCfg = Debug|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Debug|ARM.Build.0 = Debug|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Debug|x64.Build.0 = Debug|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Debug|x86.Build.0 = Debug|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Release|ARM.ActiveCfg = Release|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Release|ARM.Build.0 = Release|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Release|x64.ActiveCfg = Release|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Release|x64.Build.0 = Release|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Release|x86.ActiveCfg = Release|Any CPU
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}.Release|x86.Build.0 = Release|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Debug|ARM.ActiveCfg = Debug|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Debug|ARM.Build.0 = Debug|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Debug|x64.Build.0 = Debug|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Debug|x86.Build.0 = Debug|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Release|Any CPU.Build.0 = Release|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Release|ARM.ActiveCfg = Release|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Release|ARM.Build.0 = Release|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Release|x64.ActiveCfg = Release|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Release|x64.Build.0 = Release|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Release|x86.ActiveCfg = Release|Any CPU
+		{D260D63D-7902-4C55-9665-84C5CACBBB24}.Release|x86.Build.0 = Release|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Debug|ARM.ActiveCfg = Debug|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Debug|ARM.Build.0 = Debug|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Debug|x64.Build.0 = Debug|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Debug|x86.Build.0 = Debug|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Release|Any CPU.Build.0 = Release|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Release|ARM.ActiveCfg = Release|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Release|ARM.Build.0 = Release|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Release|x64.ActiveCfg = Release|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Release|x64.Build.0 = Release|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Release|x86.ActiveCfg = Release|Any CPU
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{A7FF0C91-25DE-4BA6-B39E-F54E8DADF1CC} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
-		{FF1F72D6-9524-4422-9497-3CC0002216ED} = {A56E3128-1639-4F31-873A-325E14BB6295}
 		{3587E506-55A2-4EB3-99C7-DC01E42D25D2} = {32A630A7-2598-41D7-B625-204CD906F5FB}
 		{3D283AAD-AAA8-4339-8394-52F80B6304DB} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
 		{C6FF8AEA-0855-41EC-A1F3-AC262225BAB9} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
@@ -283,6 +313,10 @@ Global
 		{61B62223-F5D0-48E4-BBD6-2CBA9353CB5E} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
 		{5699FB8C-838C-4AB0-80A5-9CA809F9B65B} = {A56E3128-1639-4F31-873A-325E14BB6295}
 		{2BD01D53-4CA5-4142-BE8D-313876395E3E} = {12816BCC-AF9E-44A9-9AE5-C246AF2A0587}
+		{61B165A0-5AA8-4E04-A53D-A22A84AA6EB7} = {9248C2E1-B9D6-40BF-81EC-86004D7765B4}
+		{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F} = {61B165A0-5AA8-4E04-A53D-A22A84AA6EB7}
+		{D260D63D-7902-4C55-9665-84C5CACBBB24} = {61B165A0-5AA8-4E04-A53D-A22A84AA6EB7}
+		{DDB069BA-6E1A-48C7-B374-5D903B553CAD} = {61B165A0-5AA8-4E04-A53D-A22A84AA6EB7}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {07536672-5CBC-4BE3-ACE0-708A431A7894}
@@ -11,4 +11,5 @@
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002EAddAccessorOwnerDeclarationBracesMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002ECSharpPlaceAttributeOnSameLineMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002EMigrateBlankLinesAroundFieldToBlankLinesAroundProperty/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002EMigrateThisQualifierSettings/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>
+	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002EMigrateThisQualifierSettings/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=unsub/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>
@@ -19,7 +19,7 @@ MQTTnet is a high performance .NET library for MQTT based communication. It prov
 ### General

 * Async support
-* TLS 1.2 support for client and server (but not UWP servers)
+* TLS support for client and server (but not UWP servers)
 * Extensible communication channels (e.g. In-Memory, TCP, TCP+TLS, WS)
 * Lightweight (only the low level implementation of MQTT, no overhead)
 * Performance optimized (processing ~70.000 messages / second)*
@@ -64,14 +64,32 @@ _MQTTnet Server_ is a standalone cross platform MQTT server (like mosquitto) bas

 ## Supported frameworks

+* .NET 5.0+
 * .NET Standard 1.3+
 * .NET Core 1.1+
 * .NET Core App 1.1+
-* .NET Framework 4.5.2+ (x86, x64, AnyCPU)
+* .NET Framework 4.5.2+
 * Mono 5.2+
-* Universal Windows Platform (UWP) 10.0.10240+ (x86, x64, ARM, AnyCPU, Windows 10 IoT Core)
+* Universal Windows Platform (UWP) 10.0.10240+ (Windows 10 IoT Core)
 * Xamarin.Android 7.5+
 * Xamarin.iOS 10.14+
+* Blazor WebAssembly 3.2.0+
+
+## Supported platforms
+
+* x86
+* x64
+* AnyCPU
+* ARM
+
+## Supported OS
+
+* Windows
+* Windows 10 IoT Core
+* Linux (Ubuntu, Raspbian etc.)
+* macOS
+* Android
+* iOS

 ## Supported MQTT versions

@@ -96,11 +114,14 @@ Also additions and updates in the Wiki are welcome.

 This library is used in the following projects:

-* Azure Functions MQTT Bindings, [CaseOnline.Azure.WebJobs.Extensions.Mqtt](https://github.com/keesschollaart81/CaseOnline.Azure.WebJobs.Extensions.Mqtt/)
+* Azure Functions MQTT Bindings, <https://github.com/keesschollaart81/CaseOnline.Azure.WebJobs.Extensions.Mqtt>)
 * HA4IoT (Open Source Home Automation system for .NET, <https://github.com/chkr1011/HA4IoT>)
 * MQTT Client Rx (Wrapper for Reactive Extensions, <https://github.com/1iveowl/MQTTClient.rx>)
+* MQTT Client Rx (Managed Client Wrapper for Reactive Extensions, <https://github.com/mmuecke/RxMQTTnet>)
 * MQTT Tester (MQTT client test app for [Android](https://play.google.com/store/apps/details?id=com.liveowl.mqtttester) and [iOS](https://itunes.apple.com/us/app/mqtt-tester/id1278621826?mt=8))
+* MQTTnet App (Cross platform client application for MQTT debugging, inspection etc., <https://github.com/chkr1011/MQTTnet.App>)
 * Wirehome.Core (Open Source Home Automation system for .NET Core, <https://github.com/chkr1011/Wirehome.Core>)
+* SparkplugNet (Sparkplug library for .Net, <https://github.com/SeppPenner/SparkplugNet>)

 Further projects using this project can be found under https://github.com/chkr1011/MQTTnet/network/dependents.

@@ -110,7 +131,7 @@ If you use this library and want to see your project here please create a pull r

 MIT License

-MQTTnet Copyright (c) 2016-2020 Christian Kratky
+MQTTnet Copyright (c) 2016-2021 Christian Kratky

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -40,7 +40,7 @@ namespace MQTTnet.AspNetCore.Client.Tcp
            _sender = new SocketSender(_socket, PipeScheduler.ThreadPool);
            _receiver = new SocketReceiver(_socket, PipeScheduler.ThreadPool);
        }
-#if NETCOREAPP3_1
+#if NETCOREAPP3_1 || NET5_0
        public override ValueTask DisposeAsync()
 #else
        public Task DisposeAsync()
@@ -53,7 +53,7 @@ namespace MQTTnet.AspNetCore.Client.Tcp

            _socket?.Dispose();

-#if NETCOREAPP3_1
+#if NETCOREAPP3_1 || NET5_0

            return base.DisposeAsync();
        }
@@ -3,7 +3,7 @@ using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.DependencyInjection;
 using MQTTnet.Server;

-namespace MQTTnet.AspNetCore
+namespace MQTTnet.AspNetCore.Extensions
 {
    public static class ApplicationBuilderExtensions
    {
@@ -1,6 +1,6 @@
 using Microsoft.AspNetCore.Connections;

-namespace MQTTnet.AspNetCore
+namespace MQTTnet.AspNetCore.Extensions
 {
    public static class ConnectionBuilderExtensions
    {
@@ -1,14 +1,18 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Connections;
-using System;

-namespace MQTTnet.AspNetCore
+#if NETCOREAPP3_1
+using System;
+#endif
+
+namespace MQTTnet.AspNetCore.Extensions
 {
    public static class ConnectionRouteBuilderExtensions
    {
 #if NETCOREAPP3_1
        [Obsolete("This class is obsolete and will be removed in a future version. The recommended alternative is to use MapMqtt inside Microsoft.AspNetCore.Builder.UseEndpoints(...).")]
 #endif
+#if NETCOREAPP3_1 || NETCOREAPP2_1 || NETSTANDARD
        public static void MapMqtt(this ConnectionsRouteBuilder connection, PathString path)
        {
            connection.MapConnectionHandler<MqttConnectionHandler>(path, options =>
@@ -16,5 +20,6 @@ namespace MQTTnet.AspNetCore
                options.WebSockets.SubProtocolSelector = MqttSubProtocolSelector.SelectSubProtocol;
            });
        }
+#endif
    }
 }
@@ -1,5 +1,5 @@

-#if NETCOREAPP3_1
+#if NETCOREAPP3_1 || NET5_0

 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Routing;
@@ -5,7 +5,7 @@ using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
 using MQTTnet.Packets;

-namespace MQTTnet.AspNetCore
+namespace MQTTnet.AspNetCore.Extensions
 {
    public static class ReaderExtensions
    {
@@ -1,12 +1,12 @@
-using Microsoft.Extensions.DependencyInjection;
+using System;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
 using MQTTnet.Implementations;
 using MQTTnet.Server;
-using System;

-namespace MQTTnet.AspNetCore
+namespace MQTTnet.AspNetCore.Extensions
 {
    public static class ServiceCollectionExtensions
    {
@@ -1,25 +1,32 @@
 <Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;netcoreapp2.1;netcoreapp3.1</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netcoreapp2.1;netcoreapp3.1;net5.0</TargetFrameworks>
    <Product />
    <Company />
    <Authors />
    <PackageId />
    <LangVersion>7.2</LangVersion>
    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <PublishRepositoryUrl>true</PublishRepositoryUrl>
+    <IncludeSymbols>true</IncludeSymbols>
+    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
  </PropertyGroup>

+  <ItemGroup>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
+  </ItemGroup>
+
  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
    <DefineConstants>RELEASE;NETSTANDARD2_0</DefineConstants>
  </PropertyGroup>

-  <ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp3.1'">
+  <ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp3.1' or '$(TargetFramework)' == 'net5.0' ">
    <FrameworkReference Include="Microsoft.AspNetCore.App" />
  </ItemGroup>
    
-  <ItemGroup Condition="'$(TargetFramework)' != 'netcoreapp3.1'">
-    <PackageReference Include="Microsoft.AspNetCore.Http.Connections" Version="1.0.0" />
+  <ItemGroup Condition="'$(TargetFramework)' != 'netcoreapp3.1' and '$(TargetFramework)' != 'net5.0' ">
+    <PackageReference Include="Microsoft.AspNetCore.Http.Connections" Version="1.1.0" />
  </ItemGroup>

  <ItemGroup>
@@ -10,11 +10,19 @@ using System.IO.Pipelines;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.AspNetCore.Extensions;
+using MQTTnet.Internal;

 namespace MQTTnet.AspNetCore
 {
-    public class MqttConnectionContext : IMqttChannelAdapter
+    public sealed class MqttConnectionContext : IMqttChannelAdapter
    {
+        readonly AsyncLock _writerLock = new AsyncLock();
+        readonly SpanBasedMqttPacketBodyReader _reader;
+        
+        PipeReader _input;
+        PipeWriter _output;
+        
        public MqttConnectionContext(MqttPacketFormatterAdapter packetFormatterAdapter, ConnectionContext connection)
        {
            PacketFormatterAdapter = packetFormatterAdapter ?? throw new ArgumentNullException(nameof(packetFormatterAdapter));
@@ -29,10 +37,6 @@ namespace MQTTnet.AspNetCore
            _reader = new SpanBasedMqttPacketBodyReader();
        }

-        private PipeReader _input;
-        private PipeWriter _output;
-        private readonly SpanBasedMqttPacketBodyReader _reader;
-
        public string Endpoint
        {
            get
@@ -57,18 +61,17 @@ namespace MQTTnet.AspNetCore

        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; set; }
+
        public long BytesReceived { get; set; }

-        public Action ReadingPacketStartedCallback { get; set; }
-        public Action ReadingPacketCompletedCallback { get; set; }
+        public bool IsReadingPacket { get; private set; }

-        private readonly SemaphoreSlim _writerSemaphore = new SemaphoreSlim(1, 1);
+        IHttpContextFeature Http => Connection.Features.Get<IHttpContextFeature>();

        public async Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
        {
@@ -89,7 +92,7 @@ namespace MQTTnet.AspNetCore
            return Task.CompletedTask;
        }

-        public async Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout, CancellationToken cancellationToken)
+        public async Task<MqttBasePacket> ReceivePacketAsync(CancellationToken cancellationToken)
        {
            var input = Connection.Transport.Input;

@@ -125,7 +128,7 @@ namespace MQTTnet.AspNetCore
                            else
                            {
                                // we did receive something but the message is not yet complete
-                                ReadingPacketStartedCallback?.Invoke();
+                                IsReadingPacket = true;
                            }
                        }
                        else if (readResult.IsCompleted)
@@ -142,9 +145,16 @@ namespace MQTTnet.AspNetCore
                    }
                }
            }
+            catch (Exception e)
+            {
+                // completing the channel makes sure that there is no more data read after a protocol error
+                _input?.Complete(e);
+                _output?.Complete(e);
+                throw;
+            }
            finally
            {
-                ReadingPacketCompletedCallback?.Invoke();
+                IsReadingPacket = false;
            }

            cancellationToken.ThrowIfCancellationRequested();
@@ -157,16 +167,14 @@ namespace MQTTnet.AspNetCore
            BytesSent = 0;
        }

-        public async Task SendPacketAsync(MqttBasePacket packet, TimeSpan timeout, CancellationToken cancellationToken)
+        public async Task SendPacketAsync(MqttBasePacket packet, CancellationToken cancellationToken)
        {
            var formatter = PacketFormatterAdapter;
-            var buffer = formatter.Encode(packet);
-            var msg = buffer.AsMemory();
-            var output = _output;
-
-            await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
-            try
+            using (await _writerLock.WaitAsync(cancellationToken).ConfigureAwait(false))
            {
+                var buffer = formatter.Encode(packet);
+                var msg = buffer.AsMemory();
+                var output = _output;
                var result = await output.WriteAsync(msg, cancellationToken).ConfigureAwait(false);
                if (result.IsCompleted)
                {
@@ -175,10 +183,6 @@ namespace MQTTnet.AspNetCore

                PacketFormatterAdapter.FreeBuffer();
            }
-            finally
-            {
-                _writerSemaphore.Release();
-            }
        }

        public void Dispose()
@@ -1,12 +1,29 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Linq;
+using Microsoft.AspNetCore.Http;

 namespace MQTTnet.AspNetCore
 {
    public static class MqttSubProtocolSelector
    {
+        public static string SelectSubProtocol(HttpRequest request)
+        {
+            if (request == null) throw new ArgumentNullException(nameof(request));
+
+            string subProtocol = null;
+            if (request.Headers.TryGetValue("Sec-WebSocket-Protocol", out var requestedSubProtocolValues))
+            {
+                subProtocol = SelectSubProtocol(requestedSubProtocolValues);
+            }
+
+            return subProtocol;
+        }
+        
        public static string SelectSubProtocol(IList<string> requestedSubProtocolValues)
        {
+            if (requestedSubProtocolValues == null) throw new ArgumentNullException(nameof(requestedSubProtocolValues));
+
            // Order the protocols to also match "mqtt", "mqttv-3.1", "mqttv-3.11" etc.
            return requestedSubProtocolValues
                .OrderByDescending(p => p.Length)
@@ -49,7 +49,7 @@ namespace MQTTnet.AspNetCore
                    var formatter = new MqttPacketFormatterAdapter(writer);
                    var channel = new MqttWebSocketChannel(webSocket, endpoint, isSecureConnection, clientCertificate);

-                    using (var channelAdapter = new MqttChannelAdapter(channel, formatter, _rootLogger))
+                    using (var channelAdapter = new MqttChannelAdapter(channel, formatter, null, _rootLogger))
                    {
                        await clientHandler(channelAdapter).ConfigureAwait(false);
                    }
@@ -8,9 +8,9 @@ namespace MQTTnet.AspNetCore
 {
    public class SpanBasedMqttPacketBodyReader : IMqttPacketBodyReader
    {
-        private ReadOnlyMemory<byte> _buffer;
+        ReadOnlyMemory<byte> _buffer;

-        private int _offset;
+        int _offset;
        
        public void SetBuffer(ReadOnlyMemory<byte> buffer)
        {
@@ -38,16 +38,6 @@ namespace MQTTnet.AspNetCore
        {
            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()
        {
@@ -121,5 +111,19 @@ namespace MQTTnet.AspNetCore
        {
            _offset = position;
        }
+
+        ReadOnlySpan<byte> ReadSegmentWithLengthPrefix()
+        {
+            var span = _buffer.Span;
+            var length = BinaryPrimitives.ReadUInt16BigEndian(span.Slice(_offset));
+
+            if (Length < _offset + length)
+            {
+                throw new MqttProtocolViolationException($"Expected at least {_offset + 2 + length} bytes but there are only {Length} bytes");
+            }
+            var result = span.Slice(_offset + 2, length);
+            _offset += 2 + length;
+            return result;
+        }
    }
 }
@@ -8,16 +8,15 @@ namespace MQTTnet.AspNetCore
 {
    public class SpanBasedMqttPacketWriter : IMqttPacketWriter
    {
-        private readonly ArrayPool<byte> _pool;
+        readonly ArrayPool<byte> _pool = ArrayPool<byte>.Create();

        public SpanBasedMqttPacketWriter()
        {
-            _pool = ArrayPool<byte>.Create();
-            
+            Reset(0);
        }

-        private byte[] _buffer;
-        private int _position;
+        byte[] _buffer;
+        int _position;

        public int Length { get; set; }

@@ -112,7 +111,7 @@ namespace MQTTnet.AspNetCore
            Commit(payload.Length);
        }

-        private void Commit(int count)
+        void Commit(int count)
        {
            if (_position == Length)
            {
@@ -122,7 +121,7 @@ namespace MQTTnet.AspNetCore
            _position += count;
        }

-        private void GrowIfNeeded(int requiredAdditional) 
+        void GrowIfNeeded(int requiredAdditional) 
        {
            var requiredTotal = _position + requiredAdditional;
            if (_buffer.Length >= requiredTotal)
@@ -4,30 +4,46 @@ using System;
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Client;

 namespace MQTTnet.Extensions.ManagedClient
 {
    public interface IManagedMqttClient : IApplicationMessageReceiver, IApplicationMessagePublisher, IDisposable
    {
-        bool IsStarted { get; }
-        bool IsConnected { get; }
-        int PendingApplicationMessagesCount { get; }
-        IManagedMqttClientOptions Options { get; }
+        /// <summary>
+        /// Gets the internally used MQTT client.
+        /// This property should be used with caution because manipulating the internal client might break the managed client.
+        /// </summary>
+        IMqttClient InternalClient { get; }

+        bool IsStarted { get; }
+        
+        bool IsConnected { get; }
+        
+        int PendingApplicationMessagesCount { get; }
+        
+        IManagedMqttClientOptions Options { get; }
+        
        IMqttClientConnectedHandler ConnectedHandler { get; set; }
+        
        IMqttClientDisconnectedHandler DisconnectedHandler { get; set; }

        IApplicationMessageProcessedHandler ApplicationMessageProcessedHandler { get; set; }
+        
        IApplicationMessageSkippedHandler ApplicationMessageSkippedHandler { get; set; }

        IConnectingFailedHandler ConnectingFailedHandler { get; set; }
+        
        ISynchronizingSubscriptionsFailedHandler SynchronizingSubscriptionsFailedHandler { get; set; }

        Task StartAsync(IManagedMqttClientOptions options);
+        
        Task StopAsync();
+        
        Task PingAsync(CancellationToken cancellationToken);

        Task SubscribeAsync(IEnumerable<MqttTopicFilter> topicFilters);
+        
        Task UnsubscribeAsync(IEnumerable<string> topics);

        Task PublishAsync(ManagedMqttApplicationMessage applicationMessages);
@@ -1,13 +1,16 @@
 <Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
-    <TargetFrameworks>netstandard1.3;netstandard2.0;netstandard2.1</TargetFrameworks>
+    <TargetFrameworks>netstandard1.3;netstandard2.0;netstandard2.1;net5.0</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 />
+    <PublishRepositoryUrl>true</PublishRepositoryUrl>
+    <IncludeSymbols>true</IncludeSymbols>
+    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
  </PropertyGroup>

  <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0'">
@@ -23,6 +26,10 @@
    <LanguageTargets>$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets</LanguageTargets>
  </PropertyGroup>

+  <ItemGroup>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
+  </ItemGroup>
+
  <ItemGroup>
    <ProjectReference Include="..\MQTTnet\MQTTnet.csproj" />
  </ItemGroup>
@@ -18,7 +18,7 @@ namespace MQTTnet.Extensions.ManagedClient
 {
    public class ManagedMqttClient : Disposable, IManagedMqttClient
    {
-        private readonly BlockingQueue<ManagedMqttApplicationMessage> _messageQueue = new BlockingQueue<ManagedMqttApplicationMessage>();
+        readonly BlockingQueue<ManagedMqttApplicationMessage> _messageQueue = new BlockingQueue<ManagedMqttApplicationMessage>();

        /// <summary>
        /// The subscriptions are managed in 2 separate buckets:
@@ -27,51 +27,55 @@ namespace MQTTnet.Extensions.ManagedClient
        /// any thread and are therefore mutex'ed. <see cref="_reconnectSubscriptions"/> get sent to the broker
        ///  at reconnect and are solely owned by <see cref="MaintainConnectionAsync"/>.
        /// </summary>
-        private readonly Dictionary<string, MqttQualityOfServiceLevel> _reconnectSubscriptions = new Dictionary<string, MqttQualityOfServiceLevel>();
-        private readonly Dictionary<string, MqttQualityOfServiceLevel> _subscriptions = new Dictionary<string, MqttQualityOfServiceLevel>();
-        private readonly HashSet<string> _unsubscriptions = new HashSet<string>();
-        private readonly SemaphoreSlim _subscriptionsQueuedSignal = new SemaphoreSlim(0);
+        readonly Dictionary<string, MqttQualityOfServiceLevel> _reconnectSubscriptions = new Dictionary<string, MqttQualityOfServiceLevel>();
+        readonly Dictionary<string, MqttQualityOfServiceLevel> _subscriptions = new Dictionary<string, MqttQualityOfServiceLevel>();
+        readonly HashSet<string> _unsubscriptions = new HashSet<string>();
+        readonly SemaphoreSlim _subscriptionsQueuedSignal = new SemaphoreSlim(0);

-        private readonly IMqttClient _mqttClient;
-        private readonly IMqttNetScopedLogger _logger;
+        readonly IMqttNetScopedLogger _logger;

-        private readonly AsyncLock _messageQueueLock = new AsyncLock();
+        readonly AsyncLock _messageQueueLock = new AsyncLock();

-        private CancellationTokenSource _connectionCancellationToken;
-        private CancellationTokenSource _publishingCancellationToken;
-        private Task _maintainConnectionTask;
+        CancellationTokenSource _connectionCancellationToken;
+        CancellationTokenSource _publishingCancellationToken;
+        Task _maintainConnectionTask;

-        private ManagedMqttClientStorageManager _storageManager;
+        ManagedMqttClientStorageManager _storageManager;

        public ManagedMqttClient(IMqttClient mqttClient, IMqttNetLogger logger)
        {
-            _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
+            InternalClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));

            if (logger == null) throw new ArgumentNullException(nameof(logger));
            _logger = logger.CreateScopedLogger(nameof(ManagedMqttClient));
        }

-        public bool IsConnected => _mqttClient.IsConnected;
+        public bool IsConnected => InternalClient.IsConnected;
+
        public bool IsStarted => _connectionCancellationToken != null;
+
+        public IMqttClient InternalClient { get; }
+
        public int PendingApplicationMessagesCount => _messageQueue.Count;
+
        public IManagedMqttClientOptions Options { get; private set; }

        public IMqttClientConnectedHandler ConnectedHandler
        {
-            get => _mqttClient.ConnectedHandler;
-            set => _mqttClient.ConnectedHandler = value;
+            get => InternalClient.ConnectedHandler;
+            set => InternalClient.ConnectedHandler = value;
        }

        public IMqttClientDisconnectedHandler DisconnectedHandler
        {
-            get => _mqttClient.DisconnectedHandler;
-            set => _mqttClient.DisconnectedHandler = value;
+            get => InternalClient.DisconnectedHandler;
+            set => InternalClient.DisconnectedHandler = value;
        }

        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler
        {
-            get => _mqttClient.ApplicationMessageReceivedHandler;
-            set => _mqttClient.ApplicationMessageReceivedHandler = value;
+            get => InternalClient.ApplicationMessageReceivedHandler;
+            set => InternalClient.ApplicationMessageReceivedHandler = value;
        }

        public IApplicationMessageProcessedHandler ApplicationMessageProcessedHandler { get; set; }
@@ -89,14 +93,13 @@ namespace MQTTnet.Extensions.ManagedClient
            if (options == null) throw new ArgumentNullException(nameof(options));
            if (options.ClientOptions == null) throw new ArgumentException("The client options are not set.", nameof(options));

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

            Options = options;

-            if (Options.Storage != null)
+            if (options.Storage != null)
            {
-                _storageManager = new ManagedMqttClientStorageManager(Options.Storage);
+                _storageManager = new ManagedMqttClientStorageManager(options.Storage);
                var messages = await _storageManager.LoadQueuedMessagesAsync().ConfigureAwait(false);

                foreach (var message in messages)
@@ -105,10 +108,12 @@ namespace MQTTnet.Extensions.ManagedClient
                }
            }

-            _connectionCancellationToken = new CancellationTokenSource();
+            var cancellationTokenSource = new CancellationTokenSource();
+            var cancellationToken = cancellationTokenSource.Token;
+            _connectionCancellationToken = cancellationTokenSource;

-            _maintainConnectionTask = Task.Run(() => MaintainConnectionAsync(_connectionCancellationToken.Token), _connectionCancellationToken.Token);
-            _maintainConnectionTask.Forget(_logger);
+            _maintainConnectionTask = Task.Run(() => MaintainConnectionAsync(cancellationToken), cancellationToken);
+            _maintainConnectionTask.RunInBackground(_logger);

            _logger.Info("Started");
        }
@@ -131,7 +136,7 @@ namespace MQTTnet.Extensions.ManagedClient

        public Task PingAsync(CancellationToken cancellationToken)
        {
-            return _mqttClient.PingAsync(cancellationToken);
+            return InternalClient.PingAsync(cancellationToken);
        }

        public async Task<MqttClientPublishResult> PublishAsync(MqttApplicationMessage applicationMessage, CancellationToken cancellationToken)
@@ -218,6 +223,7 @@ namespace MQTTnet.Extensions.ManagedClient
                    _unsubscriptions.Remove(topicFilter.Topic);
                }
            }
+
            _subscriptionsQueuedSignal.Release();

            return Task.FromResult(0);
@@ -257,13 +263,14 @@ namespace MQTTnet.Extensions.ManagedClient

                _messageQueue.Dispose();
                _messageQueueLock.Dispose();
-                _mqttClient.Dispose();
+                InternalClient.Dispose();
                _subscriptionsQueuedSignal.Dispose();
            }
+
            base.Dispose(disposing);
        }

-        private async Task MaintainConnectionAsync(CancellationToken cancellationToken)
+        async Task MaintainConnectionAsync(CancellationToken cancellationToken)
        {
            try
            {
@@ -285,7 +292,14 @@ namespace MQTTnet.Extensions.ManagedClient
                {
                    try
                    {
-                        await _mqttClient.DisconnectAsync().ConfigureAwait(false);
+                        using (var disconnectTimeout = new CancellationTokenSource(Options.ClientOptions.CommunicationTimeout))
+                        {
+                            await InternalClient.DisconnectAsync(disconnectTimeout.Token).ConfigureAwait(false);
+                        }
+                    }
+                    catch (OperationCanceledException)
+                    {
+                        _logger.Warning("Timeout while sending DISCONNECT packet.");
                    }
                    catch (Exception exception)
                    {
@@ -294,7 +308,9 @@ namespace MQTTnet.Extensions.ManagedClient

                    _logger.Info("Stopped");
                }
+
                _reconnectSubscriptions.Clear();
+
                lock (_subscriptions)
                {
                    _subscriptions.Clear();
@@ -303,11 +319,11 @@ namespace MQTTnet.Extensions.ManagedClient
            }
        }

-        private async Task TryMaintainConnectionAsync(CancellationToken cancellationToken)
+        async Task TryMaintainConnectionAsync(CancellationToken cancellationToken)
        {
            try
            {
-                var connectionState = await ReconnectIfRequiredAsync().ConfigureAwait(false);
+                var connectionState = await ReconnectIfRequiredAsync(cancellationToken).ConfigureAwait(false);
                if (connectionState == ReconnectionResult.NotConnected)
                {
                    StopPublishing();
@@ -346,11 +362,11 @@ namespace MQTTnet.Extensions.ManagedClient
            }
        }

-        private async Task PublishQueuedMessagesAsync(CancellationToken cancellationToken)
+        async Task PublishQueuedMessagesAsync(CancellationToken cancellationToken)
        {
            try
            {
-                while (!cancellationToken.IsCancellationRequested && _mqttClient.IsConnected)
+                while (!cancellationToken.IsCancellationRequested && InternalClient.IsConnected)
                {
                    // Peek at the message without dequeueing in order to prevent the
                    // possibility of the queue growing beyond the configured cap.
@@ -384,12 +400,12 @@ namespace MQTTnet.Extensions.ManagedClient
            }
        }

-        private async Task TryPublishQueuedMessageAsync(ManagedMqttApplicationMessage message)
+        async Task TryPublishQueuedMessageAsync(ManagedMqttApplicationMessage message)
        {
            Exception transmitException = null;
            try
            {
-                await _mqttClient.PublishAsync(message.ApplicationMessage).ConfigureAwait(false);
+                await InternalClient.PublishAsync(message.ApplicationMessage).ConfigureAwait(false);

                using (await _messageQueueLock.WaitAsync(CancellationToken.None).ConfigureAwait(false)) //lock to avoid conflict with this.PublishAsync
                {
@@ -411,7 +427,7 @@ namespace MQTTnet.Extensions.ManagedClient
            {
                transmitException = exception;

-                _logger.Warning(exception, $"Publishing application ({message.Id}) message failed.");
+                _logger.Warning(exception, "Publishing application message ({0}) failed.", message.Id);

                if (message.ApplicationMessage.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtMostOnce)
                {
@@ -436,7 +452,7 @@ namespace MQTTnet.Extensions.ManagedClient
            catch (Exception exception)
            {
                transmitException = exception;
-                _logger.Error(exception, $"Error while publishing application message ({message.Id}).");
+                _logger.Error(exception, "Error while publishing application message ({0}).", message.Id);
            }
            finally
            {
@@ -449,9 +465,10 @@ namespace MQTTnet.Extensions.ManagedClient
            }
        }

-        private async Task PublishSubscriptionsAsync(TimeSpan timeout, CancellationToken cancellationToken)
+        async Task PublishSubscriptionsAsync(TimeSpan timeout, CancellationToken cancellationToken)
        {
            var endTime = DateTime.UtcNow + timeout;
+
            while (await _subscriptionsQueuedSignal.WaitAsync(GetRemainingTime(endTime), cancellationToken).ConfigureAwait(false))
            {
                List<MqttTopicFilter> subscriptions;
@@ -470,7 +487,7 @@ namespace MQTTnet.Extensions.ManagedClient
                    continue;
                }

-                _logger.Verbose($"Publishing subscriptions ({subscriptions.Count} subscriptions and {unsubscriptions.Count} unsubscriptions)");
+                _logger.Verbose("Publishing {0} subscriptions and {1} unsubscriptions)", subscriptions.Count, unsubscriptions.Count);

                foreach (var unsubscription in unsubscriptions)
                {
@@ -486,12 +503,12 @@ namespace MQTTnet.Extensions.ManagedClient
                {
                    if (unsubscriptions.Any())
                    {
-                        await _mqttClient.UnsubscribeAsync(unsubscriptions.ToArray()).ConfigureAwait(false);
+                        await InternalClient.UnsubscribeAsync(unsubscriptions.ToArray()).ConfigureAwait(false);
                    }

                    if (subscriptions.Any())
                    {
-                        await _mqttClient.SubscribeAsync(subscriptions.ToArray()).ConfigureAwait(false);
+                        await InternalClient.SubscribeAsync(subscriptions.ToArray()).ConfigureAwait(false);
                    }
                }
                catch (Exception exception)
@@ -501,7 +518,7 @@ namespace MQTTnet.Extensions.ManagedClient
            }
        }

-        private async Task PublishReconnectSubscriptionsAsync()
+        async Task PublishReconnectSubscriptionsAsync()
        {
            _logger.Info("Publishing subscriptions at reconnect");

@@ -510,7 +527,7 @@ namespace MQTTnet.Extensions.ManagedClient
                if (_reconnectSubscriptions.Any())
                {
                    var subscriptions = _reconnectSubscriptions.Select(i => new MqttTopicFilter { Topic = i.Key, QualityOfServiceLevel = i.Value });
-                    await _mqttClient.SubscribeAsync(subscriptions.ToArray()).ConfigureAwait(false);
+                    await InternalClient.SubscribeAsync(subscriptions.ToArray()).ConfigureAwait(false);
                }
            }
            catch (Exception exception)
@@ -519,7 +536,7 @@ namespace MQTTnet.Extensions.ManagedClient
            }
        }

-        private async Task HandleSubscriptionExceptionAsync(Exception exception)
+        async Task HandleSubscriptionExceptionAsync(Exception exception)
        {
            _logger.Warning(exception, "Synchronizing subscriptions failed.");

@@ -530,16 +547,16 @@ namespace MQTTnet.Extensions.ManagedClient
            }
        }

-        private async Task<ReconnectionResult> ReconnectIfRequiredAsync()
+        async Task<ReconnectionResult> ReconnectIfRequiredAsync(CancellationToken cancellationToken)
        {
-            if (_mqttClient.IsConnected)
+            if (InternalClient.IsConnected)
            {
                return ReconnectionResult.StillConnected;
            }

            try
            {
-                var result = await _mqttClient.ConnectAsync(Options.ClientOptions).ConfigureAwait(false);
+                var result = await InternalClient.ConnectAsync(Options.ClientOptions, cancellationToken).ConfigureAwait(false);
                return result.IsSessionPresent ? ReconnectionResult.Recovered : ReconnectionResult.Reconnected;
            }
            catch (Exception exception)
@@ -554,34 +571,47 @@ namespace MQTTnet.Extensions.ManagedClient
            }
        }

-        private void StartPublishing()
+        void StartPublishing()
        {
            if (_publishingCancellationToken != null)
            {
                StopPublishing();
            }

-            var cts = new CancellationTokenSource();
-            _publishingCancellationToken = cts;
+            var cancellationTokenSource = new CancellationTokenSource();
+            var cancellationToken = cancellationTokenSource.Token;
+            _publishingCancellationToken = cancellationTokenSource;

-            Task.Run(() => PublishQueuedMessagesAsync(cts.Token), cts.Token).Forget(_logger);
+            Task.Run(() => PublishQueuedMessagesAsync(cancellationToken), cancellationToken).RunInBackground(_logger);
        }

-        private void StopPublishing()
+        void StopPublishing()
        {
-            _publishingCancellationToken?.Cancel(false);
-            _publishingCancellationToken?.Dispose();
-            _publishingCancellationToken = null;
+            try
+            {
+                _publishingCancellationToken?.Cancel(false);
+            }
+            finally
+            {
+                _publishingCancellationToken?.Dispose();
+                _publishingCancellationToken = null;
+            }
        }

-        private void StopMaintainingConnection()
+        void StopMaintainingConnection()
        {
-            _connectionCancellationToken?.Cancel(false);
-            _connectionCancellationToken?.Dispose();
-            _connectionCancellationToken = null;
+            try
+            {
+                _connectionCancellationToken?.Cancel(false);
+            }
+            finally
+            {
+                _connectionCancellationToken?.Dispose();
+                _connectionCancellationToken = null;
+            }
        }

-        private TimeSpan GetRemainingTime(DateTime endTime)
+        static TimeSpan GetRemainingTime(DateTime endTime)
        {
            var remainingTime = endTime - DateTime.UtcNow;
            return remainingTime < TimeSpan.Zero ? TimeSpan.Zero : remainingTime;
@@ -76,36 +76,39 @@ namespace MQTTnet.Extensions.ManagedClient
            return client;
        }

-        public static IManagedMqttClient UseApplicationMessageReceivedHandler(this IManagedMqttClient client, Func<MqttApplicationMessageReceivedEventArgs, Task> handler)
+        public static TReceiver UseApplicationMessageReceivedHandler<TReceiver>(this TReceiver receiver, Func<MqttApplicationMessageReceivedEventArgs, Task> handler)
+            where TReceiver : IApplicationMessageReceiver
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (receiver == null) throw new ArgumentNullException(nameof(receiver));

            if (handler == null)
            {
-                return client.UseApplicationMessageReceivedHandler((IMqttApplicationMessageReceivedHandler)null);
+                return receiver.UseApplicationMessageReceivedHandler((IMqttApplicationMessageReceivedHandler)null);
            }

-            return client.UseApplicationMessageReceivedHandler(new MqttApplicationMessageReceivedHandlerDelegate(handler));
+            return receiver.UseApplicationMessageReceivedHandler(new MqttApplicationMessageReceivedHandlerDelegate(handler));
        }

-        public static IManagedMqttClient UseApplicationMessageReceivedHandler(this IManagedMqttClient client, Action<MqttApplicationMessageReceivedEventArgs> handler)
+        public static TReceiver UseApplicationMessageReceivedHandler<TReceiver>(this TReceiver receiver, Action<MqttApplicationMessageReceivedEventArgs> handler)
+            where TReceiver : IApplicationMessageReceiver
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (receiver == null) throw new ArgumentNullException(nameof(receiver));

            if (handler == null)
            {
-                return client.UseApplicationMessageReceivedHandler((IMqttApplicationMessageReceivedHandler)null);
+                return receiver.UseApplicationMessageReceivedHandler((IMqttApplicationMessageReceivedHandler)null);
            }

-            return client.UseApplicationMessageReceivedHandler(new MqttApplicationMessageReceivedHandlerDelegate(handler));
+            return receiver.UseApplicationMessageReceivedHandler(new MqttApplicationMessageReceivedHandlerDelegate(handler));
        }

-        public static IManagedMqttClient UseApplicationMessageReceivedHandler(this IManagedMqttClient client, IMqttApplicationMessageReceivedHandler handler)
+        public static TReceiver UseApplicationMessageReceivedHandler<TReceiver>(this TReceiver receiver, IMqttApplicationMessageReceivedHandler handler)
+            where TReceiver : IApplicationMessageReceiver
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (receiver == null) throw new ArgumentNullException(nameof(receiver));

-            client.ApplicationMessageReceivedHandler = handler;
-            return client;
+            receiver.ApplicationMessageReceivedHandler = handler;
+            return receiver;
        }

        public static Task SubscribeAsync(this IManagedMqttClient client, params MqttTopicFilter[] topicFilters)
@@ -138,92 +141,92 @@ namespace MQTTnet.Extensions.ManagedClient
            return client.UnsubscribeAsync(topicFilters);
        }

-        public static async Task PublishAsync(this IManagedMqttClient client, IEnumerable<MqttApplicationMessage> applicationMessages)
+        public static async Task PublishAsync(this IApplicationMessagePublisher publisher, IEnumerable<MqttApplicationMessage> applicationMessages)
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
            if (applicationMessages == null) throw new ArgumentNullException(nameof(applicationMessages));

            foreach (var applicationMessage in applicationMessages)
            {
-                await client.PublishAsync(applicationMessage).ConfigureAwait(false);
+                await publisher.PublishAsync(applicationMessage).ConfigureAwait(false);
            }
        }

-        public static Task<MqttClientPublishResult> PublishAsync(this IManagedMqttClient client, MqttApplicationMessage applicationMessage)
+        public static Task<MqttClientPublishResult> PublishAsync(this IApplicationMessagePublisher publisher, MqttApplicationMessage applicationMessage)
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
            if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));

-            return client.PublishAsync(applicationMessage, CancellationToken.None);
+            return publisher.PublishAsync(applicationMessage, CancellationToken.None);
        }

-        public static async Task PublishAsync(this IManagedMqttClient client, params MqttApplicationMessage[] applicationMessages)
+        public static async Task PublishAsync(this IApplicationMessagePublisher publisher, params MqttApplicationMessage[] applicationMessages)
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
            if (applicationMessages == null) throw new ArgumentNullException(nameof(applicationMessages));

            foreach (var applicationMessage in applicationMessages)
            {
-                await client.PublishAsync(applicationMessage, CancellationToken.None).ConfigureAwait(false);
+                await publisher.PublishAsync(applicationMessage, CancellationToken.None).ConfigureAwait(false);
            }
        }

-        public static Task<MqttClientPublishResult> PublishAsync(this IManagedMqttClient client, string topic)
+        public static Task<MqttClientPublishResult> PublishAsync(this IApplicationMessagePublisher publisher, string topic)
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
            if (topic == null) throw new ArgumentNullException(nameof(topic));

-            return client.PublishAsync(builder => builder
+            return publisher.PublishAsync(builder => builder
                .WithTopic(topic));
        }

-        public static Task<MqttClientPublishResult> PublishAsync(this IManagedMqttClient client, string topic, string payload)
+        public static Task<MqttClientPublishResult> PublishAsync(this IApplicationMessagePublisher publisher, string topic, string payload)
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
            if (topic == null) throw new ArgumentNullException(nameof(topic));

-            return client.PublishAsync(builder => builder
+            return publisher.PublishAsync(builder => builder
                .WithTopic(topic)
                .WithPayload(payload));
        }

-        public static Task<MqttClientPublishResult> PublishAsync(this IManagedMqttClient client, string topic, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
+        public static Task<MqttClientPublishResult> PublishAsync(this IApplicationMessagePublisher publisher, string topic, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
            if (topic == null) throw new ArgumentNullException(nameof(topic));

-            return client.PublishAsync(builder => builder
+            return publisher.PublishAsync(builder => builder
                .WithTopic(topic)
                .WithPayload(payload)
                .WithQualityOfServiceLevel(qualityOfServiceLevel));
        }

-        public static Task<MqttClientPublishResult> PublishAsync(this IManagedMqttClient client, string topic, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel, bool retain)
+        public static Task<MqttClientPublishResult> PublishAsync(this IApplicationMessagePublisher publisher, string topic, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel, bool retain)
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
            if (topic == null) throw new ArgumentNullException(nameof(topic));

-            return client.PublishAsync(builder => builder
+            return publisher.PublishAsync(builder => builder
                .WithTopic(topic)
                .WithPayload(payload)
                .WithQualityOfServiceLevel(qualityOfServiceLevel)
                .WithRetainFlag(retain));
        }

-        public static Task<MqttClientPublishResult> PublishAsync(this IManagedMqttClient client, Func<MqttApplicationMessageBuilder, MqttApplicationMessageBuilder> builder, CancellationToken cancellationToken)
+        public static Task<MqttClientPublishResult> PublishAsync(this IApplicationMessagePublisher publisher, Func<MqttApplicationMessageBuilder, MqttApplicationMessageBuilder> builder, CancellationToken cancellationToken)
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));

            var message = builder(new MqttApplicationMessageBuilder()).Build();
-            return client.PublishAsync(message, cancellationToken);
+            return publisher.PublishAsync(message, cancellationToken);
        }

-        public static Task<MqttClientPublishResult> PublishAsync(this IManagedMqttClient client, Func<MqttApplicationMessageBuilder, MqttApplicationMessageBuilder> builder)
+        public static Task<MqttClientPublishResult> PublishAsync(this IApplicationMessagePublisher publisher, Func<MqttApplicationMessageBuilder, MqttApplicationMessageBuilder> builder)
        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));

            var message = builder(new MqttApplicationMessageBuilder()).Build();
-            return client.PublishAsync(message, CancellationToken.None);
+            return publisher.PublishAsync(message, CancellationToken.None);
        }
    }
 }
@@ -1,5 +1,4 @@
 using System;
-using MQTTnet.Client;
 using MQTTnet.Client.Options;
 using MQTTnet.Server;

@@ -1,5 +1,4 @@
 using System;
-using MQTTnet.Client;
 using MQTTnet.Client.Options;
 using MQTTnet.Server;

@@ -7,8 +6,8 @@ namespace MQTTnet.Extensions.ManagedClient
 {
    public class ManagedMqttClientOptionsBuilder
    {
-        private readonly ManagedMqttClientOptions _options = new ManagedMqttClientOptions();
-        private MqttClientOptionsBuilder _clientOptionsBuilder;
+        readonly ManagedMqttClientOptions _options = new ManagedMqttClientOptions();
+        MqttClientOptionsBuilder _clientOptionsBuilder;

        public ManagedMqttClientOptionsBuilder WithMaxPendingMessages(int value)
        {
@@ -69,7 +68,7 @@ namespace MQTTnet.Extensions.ManagedClient
            options(_clientOptionsBuilder);
            return this;
        }
-
+        
        public ManagedMqttClientOptions Build()
        {
            if (_clientOptionsBuilder != null)
@@ -0,0 +1,18 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Extensions.Rpc
+{
+    public interface IMqttRpcClient : IDisposable
+    {
+        Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel);
+
+        Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel, CancellationToken cancellationToken);
+
+        Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel);
+
+        Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, CancellationToken cancellationToken);
+    }
+}
@@ -1,13 +1,16 @@
 <Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
-    <TargetFrameworks>netstandard1.3;netstandard2.0;netstandard2.1</TargetFrameworks>
+    <TargetFrameworks>netstandard1.3;netstandard2.0;netstandard2.1;net5.0</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 />
+    <PublishRepositoryUrl>true</PublishRepositoryUrl>
+    <IncludeSymbols>true</IncludeSymbols>
+    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
  </PropertyGroup>

  <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0'">
@@ -23,6 +26,10 @@
    <LanguageTargets>$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets</LanguageTargets>
  </PropertyGroup>

+  <ItemGroup>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
+  </ItemGroup>
+
  <ItemGroup>
    <ProjectReference Include="..\MQTTnet\MQTTnet.csproj" />
  </ItemGroup>
@@ -11,12 +11,12 @@ using System.Threading.Tasks;

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

        [Obsolete("Use MqttRpcClient(IMqttClient mqttClient, IMqttRpcClientOptions options).")]
        public MqttRpcClient(IMqttClient mqttClient) : this(mqttClient, new MqttRpcClientOptions())
@@ -54,11 +54,6 @@ namespace MQTTnet.Extensions.Rpc
        {
            if (methodName == null) throw new ArgumentNullException(nameof(methodName));

-            if (methodName.Contains("/") || methodName.Contains("+") || methodName.Contains("#"))
-            {
-                throw new ArgumentException("The method name cannot contain /, + or #.");
-            }
-
            if (!(_mqttClient.ApplicationMessageReceivedHandler is RpcAwareApplicationMessageReceivedHandler))
            {
                throw new InvalidOperationException("The application message received handler was modified.");
@@ -139,7 +134,7 @@ namespace MQTTnet.Extensions.Rpc
            }
        }

-        private Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
+        Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
        {
            if (!_waitingCalls.TryRemove(eventArgs.ApplicationMessage.Topic, out var tcs))
            {
@@ -2,7 +2,7 @@

 namespace MQTTnet.Extensions.Rpc.Options
 {
-    public class MqttRpcClientOptions : IMqttRpcClientOptions
+    public sealed class MqttRpcClientOptions : IMqttRpcClientOptions
    {
        public IMqttRpcClientTopicGenerationStrategy TopicGenerationStrategy { get; set; } = new DefaultMqttRpcClientTopicGenerationStrategy();
    }
@@ -3,7 +3,7 @@ using System;

 namespace MQTTnet.Extensions.Rpc.Options
 {
-    public class MqttRpcClientOptionsBuilder
+    public sealed class MqttRpcClientOptionsBuilder
    {
        IMqttRpcClientTopicGenerationStrategy _topicGenerationStrategy = new DefaultMqttRpcClientTopicGenerationStrategy();

@@ -1,6 +1,6 @@
 namespace MQTTnet.Extensions.Rpc.Options
 {
-    public class MqttRpcTopicPair
+    public sealed class MqttRpcTopicPair
    {
        public string RequestTopic { get; set; }

@@ -1,12 +1,16 @@
-using MQTTnet.Extensions.Rpc.Options.TopicGeneration;
-using System;
+using System;

-namespace MQTTnet.Extensions.Rpc.Options
+namespace MQTTnet.Extensions.Rpc.Options.TopicGeneration
 {
-    public class DefaultMqttRpcClientTopicGenerationStrategy : IMqttRpcClientTopicGenerationStrategy
+    public sealed class DefaultMqttRpcClientTopicGenerationStrategy : IMqttRpcClientTopicGenerationStrategy
    {
        public MqttRpcTopicPair CreateRpcTopics(TopicGenerationContext context)
        {
+            if (context.MethodName.Contains("/") || context.MethodName.Contains("+") || context.MethodName.Contains("#"))
+            {
+                throw new ArgumentException("The method name cannot contain /, + or #.");
+            }
+            
            var requestTopic = $"MQTTnet.RPC/{Guid.NewGuid():N}/{context.MethodName}";
            var responseTopic = requestTopic + "/response";

@@ -3,10 +3,18 @@ using MQTTnet.Protocol;

 namespace MQTTnet.Extensions.Rpc.Options.TopicGeneration
 {
-    public class TopicGenerationContext
+    public sealed class TopicGenerationContext
    {
        public string MethodName { get; set; }

+        /// <summary>
+        /// Gets or sets the quality of service level.
+        /// The Quality of Service (QoS) level is an agreement between the sender of a message and the receiver of a message that defines the guarantee of delivery for a specific message.
+        /// There are 3 QoS levels in MQTT:
+        /// - At most once  (0): Message gets delivered no time, once or multiple times.
+        /// - At least once (1): Message gets delivered at least once (one time or more often).
+        /// - Exactly once  (2): Message gets delivered exactly once (It's ensured that the message only comes once).
+        /// </summary>
        public MqttQualityOfServiceLevel QualityOfServiceLevel { get; set; }

        public IMqttClient MqttClient { get; set; }
@@ -4,9 +4,9 @@ using MQTTnet.Client.Receiving;

 namespace MQTTnet.Extensions.Rpc
 {
-    public class RpcAwareApplicationMessageReceivedHandler : IMqttApplicationMessageReceivedHandler
+    public sealed class RpcAwareApplicationMessageReceivedHandler : IMqttApplicationMessageReceivedHandler
    {
-        private readonly Func<MqttApplicationMessageReceivedEventArgs, Task> _handleReceivedApplicationMessageAsync;
+        readonly Func<MqttApplicationMessageReceivedEventArgs, Task> _handleReceivedApplicationMessageAsync;

        public RpcAwareApplicationMessageReceivedHandler(
            IMqttApplicationMessageReceivedHandler originalHandler,
@@ -18,14 +18,14 @@ namespace MQTTnet.Extensions.Rpc

        public IMqttApplicationMessageReceivedHandler OriginalHandler { get; }

-        public async Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
+        public Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
        {
            if (OriginalHandler != null)
            {
-                await OriginalHandler.HandleApplicationMessageReceivedAsync(eventArgs).ConfigureAwait(false);
+                return OriginalHandler.HandleApplicationMessageReceivedAsync(eventArgs);
            }

-            await _handleReceivedApplicationMessageAsync(eventArgs).ConfigureAwait(false);
+            return _handleReceivedApplicationMessageAsync(eventArgs);
        }
    }
 }
@@ -1,13 +1,16 @@
 <Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
-    <TargetFrameworks>netstandard1.3;netstandard2.0;netstandard2.1</TargetFrameworks>
+    <TargetFrameworks>netstandard1.3;netstandard2.0;netstandard2.1;net5.0</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 />
+    <PublishRepositoryUrl>true</PublishRepositoryUrl>
+    <IncludeSymbols>true</IncludeSymbols>
+    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
  </PropertyGroup>

  <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0'">
@@ -23,6 +26,10 @@
    <LanguageTargets>$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets</LanguageTargets>
  </PropertyGroup>

+  <ItemGroup>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
+  </ItemGroup>
+
  <ItemGroup>
    <PackageReference Include="WebSocket4Net" Version="0.15.2" />
  </ItemGroup>
@@ -16,14 +16,14 @@ using WebSocket4Net;

 namespace MQTTnet.Extensions.WebSocket4Net
 {
-    public class WebSocket4NetMqttChannel : IMqttChannel
+    public sealed class WebSocket4NetMqttChannel : IMqttChannel
    {
-        private readonly BlockingCollection<byte> _receiveBuffer = new BlockingCollection<byte>();
+        readonly BlockingCollection<byte> _receiveBuffer = new BlockingCollection<byte>();

-        private readonly IMqttClientOptions _clientOptions;
-        private readonly MqttClientWebSocketOptions _webSocketOptions;
+        readonly IMqttClientOptions _clientOptions;
+        readonly MqttClientWebSocketOptions _webSocketOptions;

-        private WebSocket _webSocket;
+        WebSocket _webSocket;

        public WebSocket4NetMqttChannel(IMqttClientOptions clientOptions, MqttClientWebSocketOptions webSocketOptions)
        {
@@ -166,12 +166,12 @@ namespace MQTTnet.Extensions.WebSocket4Net
            _webSocket = null;
        }

-        private void OnError(object sender, ErrorEventArgs e)
+        static void OnError(object sender, ErrorEventArgs e)
        {
            System.Diagnostics.Debug.Write(e.Exception.ToString());
        }

-        private void OnDataReceived(object sender, DataReceivedEventArgs e)
+        void OnDataReceived(object sender, DataReceivedEventArgs e)
        {
            foreach (var @byte in e.Data)
            {
@@ -179,7 +179,7 @@ namespace MQTTnet.Extensions.WebSocket4Net
            }
        }

-        private async Task ConnectInternalAsync(CancellationToken cancellationToken)
+        async Task ConnectInternalAsync(CancellationToken cancellationToken)
        {
            _webSocket.Error += OnError;
            _webSocket.DataReceived += OnDataReceived;
@@ -201,7 +201,9 @@ namespace MQTTnet.Extensions.WebSocket4Net
                _webSocket.Opened += SuccessHandler;
                _webSocket.Error += ErrorHandler;

+#pragma warning disable AsyncFixer02 // Long-running or blocking operations inside an async method
                _webSocket.Open();
+#pragma warning restore AsyncFixer02 // Long-running or blocking operations inside an async method

                var exception = await MqttTaskTimeout.WaitAsync(c =>
                {
@@ -7,7 +7,7 @@ using System;

 namespace MQTTnet.Extensions.WebSocket4Net
 {
-    public class WebSocket4NetMqttClientAdapterFactory : IMqttClientAdapterFactory
+    public sealed class WebSocket4NetMqttClientAdapterFactory : IMqttClientAdapterFactory
    {
        readonly IMqttNetLogger _logger;

@@ -23,14 +23,22 @@ namespace MQTTnet.Extensions.WebSocket4Net
            switch (options.ChannelOptions)
            {
                case MqttClientTcpOptions _:
-                    {
-                        return new MqttChannelAdapter(new MqttTcpChannel(options), new MqttPacketFormatterAdapter(options.ProtocolVersion), _logger);
-                    }
+                {
+                    return new MqttChannelAdapter(
+                        new MqttTcpChannel(options),
+                        new MqttPacketFormatterAdapter(options.ProtocolVersion),
+                        options.PacketInspector,
+                        _logger);
+                }

                case MqttClientWebSocketOptions webSocketOptions:
-                    {
-                        return new MqttChannelAdapter(new WebSocket4NetMqttChannel(options, webSocketOptions), new MqttPacketFormatterAdapter(options.ProtocolVersion), _logger);
-                    }
+                {
+                    return new MqttChannelAdapter(
+                        new WebSocket4NetMqttChannel(options, webSocketOptions),
+                        new MqttPacketFormatterAdapter(options.ProtocolVersion), 
+                        options.PacketInspector,
+                        _logger);
+                }

                default:
                    {
@@ -1,134 +0,0 @@
-using MQTTnet.Client;
-using System;
-using System.Collections.Concurrent;
-using System.Linq;
-using System.Security.Authentication;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Adapter;
-using MQTTnet.Channel;
-using MQTTnet.Diagnostics;
-using MQTTnet.Serializer;
-using WebSocket4Net;
-
-namespace MQTTnet.TestApp.NetCore
-{
-    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));
-
-            if (!(options.ChannelOptions is MqttClientWebSocketOptions))
-            {
-                throw new NotSupportedException("Only WebSocket connections are supported.");
-            }
-
-            return new MqttChannelAdapter(new WebSocket4NetMqttChannel(options), new MqttPacketSerializer(), logger);
-        }
-
-        private class WebSocket4NetMqttChannel : IMqttChannel
-        {
-            private readonly BlockingCollection<byte> _receiveBuffer = new BlockingCollection<byte>();
-
-            private readonly IMqttClientOptions _clientOptions;
-            private WebSocket4Net.WebSocket _webSocket;
-
-            public WebSocket4NetMqttChannel(IMqttClientOptions clientOptions)
-            {
-                _clientOptions = clientOptions ?? throw new ArgumentNullException(nameof(clientOptions));
-            }
-
-            public string Endpoint { get; } = "";
-
-            public Task ConnectAsync(CancellationToken cancellationToken)
-            {
-                var channelOptions = (MqttClientWebSocketOptions)_clientOptions.ChannelOptions;
-
-                var uri = "ws://" + channelOptions.Uri;
-                var sslProtocols = SslProtocols.None;
-
-                if (channelOptions.TlsOptions.UseTls)
-                {
-                    uri = "wss://" + channelOptions.Uri;
-                    sslProtocols = SslProtocols.Tls12;
-                }
-
-                var subProtocol = channelOptions.SubProtocols.FirstOrDefault() ?? string.Empty;
-
-                _webSocket = new WebSocket4Net.WebSocket(uri, subProtocol, sslProtocols: sslProtocols);
-                _webSocket.DataReceived += OnDataReceived;
-                _webSocket.Open();
-                SpinWait.SpinUntil(() => _webSocket.State == WebSocketState.Open, _clientOptions.CommunicationTimeout);
-
-                return Task.FromResult(0);
-            }
-
-            public Task DisconnectAsync()
-            {
-                if (_webSocket != null)
-                {
-                    _webSocket.DataReceived -= OnDataReceived;
-                    _webSocket.Close();
-                    SpinWait.SpinUntil(() => _webSocket.State == WebSocketState.Closed, _clientOptions.CommunicationTimeout);
-                }
-
-                _webSocket = null;
-
-                return Task.FromResult(0);
-            }
-
-            public Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
-            {
-                var readBytes = 0;
-                while (count > 0 && !cancellationToken.IsCancellationRequested)
-                {
-                    byte @byte;
-                    if (readBytes == 0)
-                    {
-                        // Block until at lease one byte was received.
-                        @byte = _receiveBuffer.Take(cancellationToken);
-                    }
-                    else
-                    {
-                        if (!_receiveBuffer.TryTake(out @byte))
-                        {
-                            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)
-                {
-                    _webSocket.DataReceived -= OnDataReceived;
-                    _webSocket.Dispose();
-                }
-            }
-
-            private void OnDataReceived(object sender, WebSocket4Net.DataReceivedEventArgs e)
-            {
-                foreach (var @byte in e.Data)
-                {
-                    _receiveBuffer.Add(@byte);
-                }
-            }
-        }
-    }
-}
@@ -0,0 +1,12 @@
+{
+  "version": 1,
+  "isRoot": true,
+  "tools": {
+    "dotnet-ef": {
+      "version": "3.1.4",
+      "commands": [
+        "dotnet-ef"
+      ]
+    }
+  }
+}
@@ -1,26 +1,29 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFrameworks>net5.0</TargetFrameworks>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
    <AssemblyName>MQTTnet.Server</AssemblyName>
    <RootNamespace>MQTTnet.Server</RootNamespace>
    <GeneratePackageOnBuild>False</GeneratePackageOnBuild>
    <Company />
    <Product>MQTTnet</Product>
-    <Description />
-    <Authors />
+    <Description>Standalone MQTT server with Python scripting backend.</Description>
+    <Authors>The authors of MQTTnet.Server.</Authors>
    <PackageId />
    <SignAssembly>false</SignAssembly>
    <DelaySign>false</DelaySign>
    <LangVersion>latest</LangVersion>
-    <Version>1.0.0</Version>
+    <Version>3.0.11</Version>
    <TypeScriptToolsVersion>3.3</TypeScriptToolsVersion>
  </PropertyGroup>

  <PropertyGroup>
    <StartupObject>MQTTnet.Server.Program</StartupObject>
    <UserSecretsId>c564f0de-28b4-45bf-b726-4d665d705653</UserSecretsId>
+    <Copyright>(c) Christian Kratky 2016-2020</Copyright>
+    <PackageProjectUrl>https://github.com/chkr1011/MQTTnet</PackageProjectUrl>
+    <RepositoryUrl>https://github.com/chkr1011/MQTTnet</RepositoryUrl>
  </PropertyGroup>

  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
@@ -29,13 +32,6 @@
    <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>
@@ -43,12 +39,19 @@
  </ItemGroup>

  <ItemGroup>
-    <PackageReference Include="IronPython" Version="2.7.10-candidate1" />
-    <PackageReference Include="IronPython.StdLib" Version="2.7.10-candidate1" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.1.3" />
-    <PackageReference Include="MSTest.TestAdapter" Version="2.1.1" />
-    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerGen" Version="5.3.3" />
-    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="5.3.3" />
+    <PackageReference Include="IronPython" Version="2.7.11" />
+    <PackageReference Include="IronPython.StdLib" Version="2.7.11" />
+    <PackageReference Include="MSTest.TestAdapter" Version="2.1.2" />
+    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerGen" Version="5.6.3" />
+    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="5.6.3" />
+  </ItemGroup>
+  
+  <ItemGroup Condition="'$(TargetFramework)' != 'net5.0'">
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.1.5" />
+  </ItemGroup>
+  
+  <ItemGroup Condition="'$(TargetFramework)' == 'net5.0'">
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="5.0.0" />
  </ItemGroup>

  <ItemGroup>
@@ -72,11 +75,19 @@
    <None Update="Web\authorization_handler.py">
      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
    </None>
+    <None Update="Web\wwwroot\Hello.txt">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+    <None Update="Web\wwwroot\mqtt_Test.html">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+    <None Update="Web\wwwroot\pahoJS_Test.html">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
  </ItemGroup>

  <ItemGroup>
    <Folder Include="Properties\PublishProfiles\" />
-    <Folder Include="Web\wwwroot\" />
  </ItemGroup>

 </Project>
@@ -212,9 +212,15 @@ namespace MQTTnet.Server.Mqtt
            // Configure encrypted connections
            if (_settings.EncryptedTcpEndPoint.Enabled)
            {
+#if NETCOREAPP3_1 || NET5_0
+                options
+                    .WithEncryptedEndpoint()
+                    .WithEncryptionSslProtocol(SslProtocols.Tls13);
+#else
                options
                    .WithEncryptedEndpoint()
                    .WithEncryptionSslProtocol(SslProtocols.Tls12);
+#endif

                if (!string.IsNullOrEmpty(_settings.EncryptedTcpEndPoint?.Certificate?.Path))
                {
@@ -3,6 +3,7 @@ using Microsoft.Extensions.Hosting;
 using MQTTnet.Server.Web;
 using System;
 using System.Diagnostics;
+using System.IO;
 using System.Reflection;

 namespace MQTTnet.Server
@@ -21,8 +22,8 @@ namespace MQTTnet.Server
                        webBuilder.ConfigureKestrel(serverOptions =>
                        {
                        })
+                        .UseWebRoot(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Web", "wwwroot"))
                        .UseStartup<Startup>();
-
                    }).Build().Run();

                return 0;
@@ -6,6 +6,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Net.Http.Headers;
 using Microsoft.OpenApi.Models;
 using Microsoft.Scripting.Utils;
+using MQTTnet.AspNetCore;
 using MQTTnet.Server.Configuration;
 using MQTTnet.Server.Logging;
 using MQTTnet.Server.Mqtt;
@@ -40,6 +41,9 @@ namespace MQTTnet.Server.Web
            DataSharingService dataSharingService,
            MqttSettingsModel mqttSettings)
        {
+            application.UseDefaultFiles();
+            application.UseStaticFiles();
+
            application.UseHsts();
            application.UseRouting();
            application.UseCors(x => x
@@ -49,9 +53,7 @@ namespace MQTTnet.Server.Web

            application.UseAuthentication();
            application.UseAuthorization();
-
-            application.UseStaticFiles();
-
+     
            application.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
@@ -81,7 +83,6 @@ namespace MQTTnet.Server.Web
        {
            services.AddCors();

-
            services.AddControllers();

            services.AddMvc()
@@ -115,10 +116,15 @@ namespace MQTTnet.Server.Web
            {
                var securityScheme = new OpenApiSecurityScheme
                {
-                    Scheme = "Basic",
+                    Scheme = "basic",
                    Name = HeaderNames.Authorization,
                    Type = SecuritySchemeType.Http,
-                    In = ParameterLocation.Header
+                    In = ParameterLocation.Header,
+                    Reference = new OpenApiReference
+                    {
+                        Type = ReferenceType.SecurityScheme,
+                        Id = "Swagger"
+                    }
                };

                c.AddSecurityDefinition("Swagger", securityScheme);
@@ -180,8 +186,7 @@ namespace MQTTnet.Server.Web

            var webSocketOptions = new WebSocketOptions
            {
-                KeepAliveInterval = TimeSpan.FromSeconds(mqttSettings.WebSocketEndPoint.KeepAliveInterval),
-                ReceiveBufferSize = mqttSettings.WebSocketEndPoint.ReceiveBufferSize
+                KeepAliveInterval = TimeSpan.FromSeconds(mqttSettings.WebSocketEndPoint.KeepAliveInterval)
            };

            if (mqttSettings.WebSocketEndPoint.AllowedOrigins?.Any() == true)
@@ -197,7 +202,13 @@ namespace MQTTnet.Server.Web
                {
                    if (context.WebSockets.IsWebSocketRequest)
                    {
-                        using (var webSocket = await context.WebSockets.AcceptWebSocketAsync().ConfigureAwait(false))
+                        string subProtocol = null;
+                        if (context.Request.Headers.TryGetValue("Sec-WebSocket-Protocol", out var requestedSubProtocolValues))
+                        {
+                            subProtocol = MqttSubProtocolSelector.SelectSubProtocol(requestedSubProtocolValues);
+                        }
+
+                        using (var webSocket = await context.WebSockets.AcceptWebSocketAsync(subProtocol).ConfigureAwait(false))
                        {
                            await mqttServerService.RunWebSocketConnectionAsync(webSocket, context).ConfigureAwait(false);
                        }
@@ -0,0 +1 @@
+World
@@ -0,0 +1,33 @@
+<html>
+
+<head>
+    <title>MQTT JS Example</title>
+
+    <script src="https://cdn.jsdelivr.net/npm/mqtt@4.0.1/dist/mqtt.min.js" type="text/javascript"></script>
+
+    <script type="text/javascript">
+        var client = mqtt.connect('ws://localhost:80/mqtt')
+
+        client.on('connect', function () {
+            client.subscribe('mqtt_subscription', function (err) {
+                console.log("Subscribed");
+            })
+        })
+
+        client.on('message', function (topic, message) {
+            console.log(topic);
+            console.log(message.toString())
+        })
+
+        function buttonClick() {
+            client.publish("MQTT_JS_TOPIC", "payload");
+        }
+    </script>
+
+</head>
+
+<body>
+    <button onclick="buttonClick()">Publish</button>
+</body>
+
+</html>
@@ -0,0 +1,41 @@
+<html>
+
+<head>
+    <title>paho JS Example</title>
+
+    <script src="https://cdnjs.cloudflare.com/ajax/libs/paho-mqtt/1.0.1/mqttws31.js" type="text/javascript"></script>
+
+    <script type="text/javascript">
+        var mqttClient = new Paho.MQTT.Client("localhost", 80, "/mqtt", "pahoJS_client");
+        mqttClient.onConnectionLost = onConnectionLost;
+        mqttClient.onMessageArrived = onMessageArrived;
+        mqttClient.connect({ onSuccess: onConnect });
+
+        function onConnect() {
+            console.log("MQTT client connected");
+            mqttClient.subscribe("pahoJS_subscription");
+        }
+
+        function onConnectionLost(responseObject) {
+            if (responseObject.errorCode !== 0) {
+                console.log("onConnectionLost:" + responseObject.errorMessage);
+            }
+        }
+
+        function onMessageArrived(message) {
+            console.log("onMessageArrived:" + message.payloadString);
+        }
+        function buttonClick() {
+            message = new Paho.MQTT.Message("Hello");
+            message.destinationName = "pahoJS_topic";
+            mqttClient.send(message);
+        }
+    </script>
+
+</head>
+
+<body>
+    <button onclick="buttonClick()">Publish</button>
+</body>
+
+</html>
@@ -21,17 +21,15 @@ namespace MQTTnet.Adapter

        long BytesReceived { get; }

-        Action ReadingPacketStartedCallback { get; set; }
-
-        Action ReadingPacketCompletedCallback { get; set; }
+        bool IsReadingPacket { get; }

        Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken);

        Task DisconnectAsync(TimeSpan timeout, CancellationToken cancellationToken);

-        Task SendPacketAsync(MqttBasePacket packet, TimeSpan timeout, CancellationToken cancellationToken);
+        Task SendPacketAsync(MqttBasePacket packet, CancellationToken cancellationToken);

-        Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout, CancellationToken cancellationToken);
+        Task<MqttBasePacket> ReceivePacketAsync(CancellationToken cancellationToken);

        void ResetStatistics();
    }
@@ -11,34 +11,35 @@ using System.Runtime.InteropServices;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.PacketInspection;

 namespace MQTTnet.Adapter
 {
    public sealed class MqttChannelAdapter : Disposable, IMqttChannelAdapter
    {
-        const uint _errorOperationAborted = 0x800703E3;
-        const int _readBufferSize = 4096;  // TODO: Move buffer size to config
-
-        readonly IMqttNetScopedLogger _logger;
-        readonly IMqttChannel _channel;
-        readonly MqttPacketReader _packetReader;
+        const uint ErrorOperationAborted = 0x800703E3;
+        const int ReadBufferSize = 4096;

+        readonly byte[] _singleByteBuffer = new byte[1];
        readonly byte[] _fixedHeaderBuffer = new byte[2];

-        SemaphoreSlim _writerSemaphore = new SemaphoreSlim(1, 1);
+        readonly MqttPacketInspectorHandler _packetInspectorHandler;
+        readonly IMqttNetScopedLogger _logger;
+        readonly IMqttChannel _channel;
+
+        readonly AsyncLock _syncRoot = new AsyncLock();

        long _bytesReceived;
        long _bytesSent;

-        public MqttChannelAdapter(IMqttChannel channel, MqttPacketFormatterAdapter packetFormatterAdapter, IMqttNetLogger logger)
+        public MqttChannelAdapter(IMqttChannel channel, MqttPacketFormatterAdapter packetFormatterAdapter, IMqttPacketInspector packetInspector, IMqttNetLogger logger)
        {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
-
            _channel = channel ?? throw new ArgumentNullException(nameof(channel));
            PacketFormatterAdapter = packetFormatterAdapter ?? throw new ArgumentNullException(nameof(packetFormatterAdapter));

-            _packetReader = new MqttPacketReader(_channel);
+            _packetInspectorHandler = new MqttPacketInspectorHandler(packetInspector, logger);

+            if (logger == null) throw new ArgumentNullException(nameof(logger));
            _logger = logger.CreateScopedLogger(nameof(MqttChannelAdapter));
        }

@@ -51,13 +52,14 @@ namespace MQTTnet.Adapter
        public MqttPacketFormatterAdapter PacketFormatterAdapter { get; }

        public long BytesSent => Interlocked.Read(ref _bytesSent);
+
        public long BytesReceived => Interlocked.Read(ref _bytesReceived);

-        public Action ReadingPacketStartedCallback { get; set; }
-        public Action ReadingPacketCompletedCallback { get; set; }
+        public bool IsReadingPacket { get; private set; }

        public async Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
        {
+            cancellationToken.ThrowIfCancellationRequested();
            ThrowIfDisposed();

            try
@@ -78,12 +80,13 @@ namespace MQTTnet.Adapter
                    throw;
                }

-                WrapException(exception);
+                WrapAndThrowException(exception);
            }
        }

        public async Task DisconnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
        {
+            cancellationToken.ThrowIfCancellationRequested();
            ThrowIfDisposed();

            try
@@ -105,88 +108,87 @@ namespace MQTTnet.Adapter
                    throw;
                }

-                WrapException(exception);
+                WrapAndThrowException(exception);
            }
        }

-        public async Task SendPacketAsync(MqttBasePacket packet, TimeSpan timeout, CancellationToken cancellationToken)
+        public async Task SendPacketAsync(MqttBasePacket packet, CancellationToken cancellationToken)
        {
-            await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
-            try
-            {
-                var packetData = PacketFormatterAdapter.Encode(packet);
+            cancellationToken.ThrowIfCancellationRequested();
+            ThrowIfDisposed();

-                if (timeout == TimeSpan.Zero)
+            using (await _syncRoot.WaitAsync(cancellationToken).ConfigureAwait(false))
+            {
+                // Check for cancellation here again because "WaitAsync" might take some time.
+                cancellationToken.ThrowIfCancellationRequested();
+
+                try
                {
+                    var packetData = PacketFormatterAdapter.Encode(packet);
+                    _packetInspectorHandler.BeginSendPacket(packetData);
+
                    await _channel.WriteAsync(packetData.Array, packetData.Offset, packetData.Count, cancellationToken).ConfigureAwait(false);
+
+                    Interlocked.Add(ref _bytesReceived, packetData.Count);
+
+                    _logger.Verbose("TX ({0} bytes) >>> {1}", packetData.Count, packet);
                }
-                else
+                catch (Exception exception)
                {
-                    await MqttTaskTimeout.WaitAsync(
-                        t => _channel.WriteAsync(packetData.Array, packetData.Offset, packetData.Count, t), timeout, cancellationToken).ConfigureAwait(false);
+                    if (IsWrappedException(exception))
+                    {
+                        throw;
+                    }
+
+                    WrapAndThrowException(exception);
                }
-
-                Interlocked.Add(ref _bytesReceived, packetData.Count);
-
-                _logger.Verbose("TX ({0} bytes) >>> {1}", packetData.Count, packet);
-            }
-            catch (Exception exception)
-            {
-                if (IsWrappedException(exception))
+                finally
                {
-                    throw;
+                    PacketFormatterAdapter.FreeBuffer();
                }
-
-                WrapException(exception);
-            }
-            finally
-            {
-                PacketFormatterAdapter.FreeBuffer();
-                _writerSemaphore?.Release();
            }
        }

-        public async Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout, CancellationToken cancellationToken)
+        public async Task<MqttBasePacket> ReceivePacketAsync(CancellationToken cancellationToken)
        {
+            cancellationToken.ThrowIfCancellationRequested();
            ThrowIfDisposed();

            try
            {
-                ReceivedMqttPacket receivedMqttPacket;
-                if (timeout == TimeSpan.Zero)
-                {
-                    receivedMqttPacket = await ReceiveAsync(cancellationToken).ConfigureAwait(false);
-                }
-                else
-                {
-                    receivedMqttPacket = await MqttTaskTimeout.WaitAsync(ReceiveAsync, timeout, cancellationToken).ConfigureAwait(false);
-                }
+                _packetInspectorHandler.BeginReceivePacket();

-                if (receivedMqttPacket == null || cancellationToken.IsCancellationRequested)
+                var receivedPacket = await ReceiveAsync(cancellationToken).ConfigureAwait(false);
+                if (receivedPacket == null || cancellationToken.IsCancellationRequested)
                {
                    return null;
                }

-                Interlocked.Add(ref _bytesSent, receivedMqttPacket.TotalLength);
+                _packetInspectorHandler.EndReceivePacket();
+
+                Interlocked.Add(ref _bytesSent, receivedPacket.TotalLength);

                if (PacketFormatterAdapter.ProtocolVersion == MqttProtocolVersion.Unknown)
                {
-                    PacketFormatterAdapter.DetectProtocolVersion(receivedMqttPacket);
+                    PacketFormatterAdapter.DetectProtocolVersion(receivedPacket);
                }

-                var packet = PacketFormatterAdapter.Decode(receivedMqttPacket);
+                var packet = PacketFormatterAdapter.Decode(receivedPacket);
                if (packet == null)
                {
                    throw new MqttProtocolViolationException("Received malformed packet.");
                }

-                _logger.Verbose("RX ({0} bytes) <<< {1}", receivedMqttPacket.TotalLength, packet);
+                _logger.Verbose("RX ({0} bytes) <<< {1}", receivedPacket.TotalLength, packet);

                return packet;
            }
            catch (OperationCanceledException)
            {
            }
+            catch (ObjectDisposedException)
+            {
+            }
            catch (Exception exception)
            {
                if (IsWrappedException(exception))
@@ -194,7 +196,7 @@ namespace MQTTnet.Adapter
                    throw;
                }

-                WrapException(exception);
+                WrapAndThrowException(exception);
            }

            return null;
@@ -210,10 +212,8 @@ namespace MQTTnet.Adapter
        {
            if (disposing)
            {
-                _channel?.Dispose();
-
-                _writerSemaphore?.Dispose();
-                _writerSemaphore = null;
+                _channel.Dispose();
+                _syncRoot.Dispose();
            }

            base.Dispose(disposing);
@@ -221,31 +221,38 @@ namespace MQTTnet.Adapter

        async Task<ReceivedMqttPacket> ReceiveAsync(CancellationToken cancellationToken)
        {
-            var readFixedHeaderResult = await _packetReader.ReadFixedHeaderAsync(_fixedHeaderBuffer, cancellationToken).ConfigureAwait(false);
+            if (cancellationToken.IsCancellationRequested)
+            {
+                return null;
+            }
+
+            var readFixedHeaderResult = await ReadFixedHeaderAsync(cancellationToken).ConfigureAwait(false);

            if (cancellationToken.IsCancellationRequested)
            {
                return null;
            }

+            if (readFixedHeaderResult.ConnectionClosed)
+            {
+                return null;
+            }
+
            try
            {
-                if (readFixedHeaderResult.ConnectionClosed)
-                {
-                    return null;
-                }
-
-                ReadingPacketStartedCallback?.Invoke();
+                IsReadingPacket = true;

                var fixedHeader = readFixedHeaderResult.FixedHeader;
                if (fixedHeader.RemainingLength == 0)
                {
-                    return new ReceivedMqttPacket(fixedHeader.Flags, null, 2);
+                    return new ReceivedMqttPacket(fixedHeader.Flags, new MqttPacketBodyReader(new byte[0], 0, 0), 2);
                }

-                var body = new byte[fixedHeader.RemainingLength];
+                var bodyLength = fixedHeader.RemainingLength;
+                var body = new byte[bodyLength];
+
                var bodyOffset = 0;
-                var chunkSize = Math.Min(_readBufferSize, fixedHeader.RemainingLength);
+                var chunkSize = Math.Min(ReadBufferSize, bodyLength);

                do
                {
@@ -268,25 +275,126 @@ namespace MQTTnet.Adapter
                    }

                    bodyOffset += readBytes;
-                } while (bodyOffset < body.Length);
+                } while (bodyOffset < bodyLength);

-                var bodyReader = new MqttPacketBodyReader(body, 0, body.Length);
+                _packetInspectorHandler.FillReceiveBuffer(body);
+
+                var bodyReader = new MqttPacketBodyReader(body, 0, bodyLength);
                return new ReceivedMqttPacket(fixedHeader.Flags, bodyReader, fixedHeader.TotalLength);
            }
            finally
            {
-                ReadingPacketCompletedCallback?.Invoke();
+                IsReadingPacket = false;
            }
        }

+        async Task<ReadFixedHeaderResult> ReadFixedHeaderAsync(CancellationToken cancellationToken)
+        {
+            // The MQTT fixed header contains 1 byte of flags and at least 1 byte for the remaining data length.
+            // So in all cases at least 2 bytes must be read for a complete MQTT packet.
+            var buffer = _fixedHeaderBuffer;
+            var totalBytesRead = 0;
+
+            while (totalBytesRead < buffer.Length)
+            {
+                var bytesRead = await _channel.ReadAsync(buffer, totalBytesRead, buffer.Length - totalBytesRead, cancellationToken).ConfigureAwait(false);
+
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    return null;
+                }
+
+                if (bytesRead == 0)
+                {
+                    return new ReadFixedHeaderResult
+                    {
+                        ConnectionClosed = true
+                    };
+                }
+
+                totalBytesRead += bytesRead;
+            }
+
+            _packetInspectorHandler.FillReceiveBuffer(buffer);
+
+            var hasRemainingLength = buffer[1] != 0;
+            if (!hasRemainingLength)
+            {
+                return new ReadFixedHeaderResult
+                {
+                    FixedHeader = new MqttFixedHeader(buffer[0], 0, totalBytesRead)
+                };
+            }
+
+            var bodyLength = await ReadBodyLengthAsync(buffer[1], cancellationToken).ConfigureAwait(false);
+
+            if (!bodyLength.HasValue)
+            {
+                return new ReadFixedHeaderResult
+                {
+                    ConnectionClosed = true
+                };
+            }
+
+            totalBytesRead += bodyLength.Value;
+            return new ReadFixedHeaderResult
+            {
+                FixedHeader = new MqttFixedHeader(buffer[0], bodyLength.Value, totalBytesRead)
+            };
+        }
+
+        async Task<int?> ReadBodyLengthAsync(byte initialEncodedByte, CancellationToken cancellationToken)
+        {
+            var offset = 0;
+            var multiplier = 128;
+            var value = initialEncodedByte & 127;
+            int encodedByte = initialEncodedByte;
+
+            while ((encodedByte & 128) != 0)
+            {
+                offset++;
+                if (offset > 3)
+                {
+                    throw new MqttProtocolViolationException("Remaining length is invalid.");
+                }
+
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    return null;
+                }
+
+                var readCount = await _channel.ReadAsync(_singleByteBuffer, 0, 1, cancellationToken).ConfigureAwait(false);
+
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    return null;
+                }
+
+                if (readCount == 0)
+                {
+                    return null;
+                }
+
+                _packetInspectorHandler.FillReceiveBuffer(_singleByteBuffer);
+
+                encodedByte = _singleByteBuffer[0];
+
+                value += (encodedByte & 127) * multiplier;
+                multiplier *= 128;
+            }
+
+            return value;
+        }
+
        static bool IsWrappedException(Exception exception)
        {
            return exception is OperationCanceledException ||
                   exception is MqttCommunicationTimedOutException ||
-                   exception is MqttCommunicationException;
+                   exception is MqttCommunicationException ||
+                   exception is MqttProtocolViolationException;
        }

-        static void WrapException(Exception exception)
+        static void WrapAndThrowException(Exception exception)
        {
            if (exception is IOException && exception.InnerException is SocketException innerException)
            {
@@ -295,16 +403,20 @@ namespace MQTTnet.Adapter

            if (exception is SocketException socketException)
            {
-                if (socketException.SocketErrorCode == SocketError.ConnectionAborted ||
-                    socketException.SocketErrorCode == SocketError.OperationAborted)
+                if (socketException.SocketErrorCode == SocketError.OperationAborted)
                {
                    throw new OperationCanceledException();
                }
+
+                if (socketException.SocketErrorCode == SocketError.ConnectionAborted)
+                {
+                    throw new MqttCommunicationException(socketException);
+                }
            }

            if (exception is COMException comException)
            {
-                if ((uint)comException.HResult == _errorOperationAborted)
+                if ((uint)comException.HResult == ErrorOperationAborted)
                {
                    throw new OperationCanceledException();
                }
@@ -0,0 +1,84 @@
+using System;
+using System.IO;
+using System.Linq;
+using MQTTnet.Diagnostics;
+using MQTTnet.Diagnostics.PacketInspection;
+
+namespace MQTTnet.Adapter
+{
+    public sealed class MqttPacketInspectorHandler
+    {
+        readonly MemoryStream _receivedPacketBuffer;
+        readonly IMqttPacketInspector _packetInspector;
+        readonly IMqttNetScopedLogger _logger;
+
+        public MqttPacketInspectorHandler(IMqttPacketInspector packetInspector, IMqttNetLogger logger)
+        {
+            _packetInspector = packetInspector;
+
+            if (packetInspector != null)
+            {
+                _receivedPacketBuffer = new MemoryStream();
+            }
+
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            _logger = logger.CreateScopedLogger(nameof(MqttPacketInspectorHandler));
+        }
+
+        public void BeginReceivePacket()
+        {
+            _receivedPacketBuffer?.SetLength(0);
+        }
+
+        public void EndReceivePacket()
+        {
+            if (_packetInspector == null)
+            {
+                return;
+            }
+
+            var buffer = _receivedPacketBuffer.ToArray();
+            _receivedPacketBuffer.SetLength(0);
+
+            InspectPacket(buffer, MqttPacketFlowDirection.Inbound);
+        }
+
+        public void BeginSendPacket(ArraySegment<byte> buffer)
+        {
+            if (_packetInspector == null)
+            {
+                return;
+            }
+
+            // Create a copy of the actual packet so that the inspector gets no access
+            // to the internal buffers. This is waste of memory but this feature is only
+            // intended for debugging etc. so that this is OK.
+            var bufferCopy = buffer.ToArray();
+
+            InspectPacket(bufferCopy, MqttPacketFlowDirection.Outbound);
+        }
+
+        public void FillReceiveBuffer(byte[] buffer)
+        {
+            _receivedPacketBuffer?.Write(buffer, 0, buffer.Length);
+        }
+
+        void InspectPacket(byte[] buffer, MqttPacketFlowDirection direction)
+        {
+            try
+            {
+                var context = new ProcessMqttPacketContext
+                {
+                    Buffer = buffer,
+                    Direction = direction
+                };
+
+                _packetInspector.ProcessMqttPacket(context);
+            }
+            catch (Exception exception)
+            {
+                _logger.Error(exception, "Error while inspecting packet.");
+            }
+        }
+    }
+}
@@ -1,19 +1,20 @@
-using MQTTnet.Formatter;
+using System;
+using MQTTnet.Formatter;

 namespace MQTTnet.Adapter
 {
-    public class ReceivedMqttPacket
+    public sealed class ReceivedMqttPacket
    {
-        public ReceivedMqttPacket(byte fixedHeader, IMqttPacketBodyReader body, int totalLength)
+        public ReceivedMqttPacket(byte fixedHeader, IMqttPacketBodyReader bodyReader, int totalLength)
        {
            FixedHeader = fixedHeader;
-            Body = body;
+            BodyReader = bodyReader ?? throw new ArgumentNullException(nameof(bodyReader));
            TotalLength = totalLength;
        }

-        public byte FixedHeader { get; set; }
+        public byte FixedHeader { get; }

-        public IMqttPacketBodyReader Body { get; }
+        public IMqttPacketBodyReader BodyReader { get; }

        public int TotalLength { get; }
    }
@@ -0,0 +1,28 @@
+using System;
+using System.Security.Cryptography.X509Certificates;
+
+namespace MQTTnet.Certificates
+{
+    public class BlobCertificateProvider : ICertificateProvider
+    {
+        public BlobCertificateProvider(byte[] blob)
+        {
+            Blob = blob ?? throw new ArgumentNullException(nameof(blob));
+        }
+
+        public byte[] Blob { get; }
+
+        public string Password { get; set; }
+
+        public X509Certificate2 GetCertificate()
+        {
+            if (string.IsNullOrEmpty(Password))
+            {
+                // Use a different overload when no password is specified. Otherwise the constructor will fail.
+                return new X509Certificate2(Blob);
+            }
+
+            return new X509Certificate2(Blob, Password);
+        }
+    }
+}
@@ -0,0 +1,9 @@
+using System.Security.Cryptography.X509Certificates;
+
+namespace MQTTnet.Certificates
+{
+    public interface ICertificateProvider
+    {
+        X509Certificate2 GetCertificate();
+    }
+}
@@ -0,0 +1,22 @@
+#if !WINDOWS_UWP
+using System;
+using System.Security.Cryptography.X509Certificates;
+
+namespace MQTTnet.Certificates
+{
+    public class X509CertificateProvider : ICertificateProvider
+    {
+        readonly X509Certificate2 _certificate;
+
+        public X509CertificateProvider(X509Certificate2 certificate)
+        {
+            _certificate = certificate ?? throw new ArgumentNullException(nameof(certificate));
+        }
+
+        public X509Certificate2 GetCertificate()
+        {
+            return _certificate;
+        }
+    }
+}
+#endif
@@ -1,11 +1,16 @@
 using System.Collections.Generic;
 using MQTTnet.Packets;
+using MQTTnet.Protocol;

 namespace MQTTnet.Client.Connecting
 {
    // TODO: Consider renaming this to _MqttClientConnectResult_
    public class MqttClientAuthenticateResult
    {
+        /// <summary>
+        /// Gets or sets the result code.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public MqttClientConnectResultCode ResultCode { get; set; }

        public bool IsSessionPresent { get; set; }
@@ -16,16 +21,34 @@ namespace MQTTnet.Client.Connecting

        public string AssignedClientIdentifier { get; set; }

+        /// <summary>
+        /// Gets or sets the authentication method.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public string AuthenticationMethod { get; set; }

+        /// <summary>
+        /// Gets or sets the authentication data.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public byte[] AuthenticationData { get; set; }

        public uint? MaximumPacketSize { get; set; }

+        /// <summary>
+        /// Gets or sets the reason string.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public string ReasonString { get; set; }

        public ushort? ReceiveMaximum { get; set; }
+        
+        public MqttQualityOfServiceLevel MaximumQoS { get; set; }

+        /// <summary>
+        /// Gets or sets the response information.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public string ResponseInformation { get; set; }

        public ushort? TopicAliasMaximum { get; set; }
@@ -36,10 +59,25 @@ namespace MQTTnet.Client.Connecting

        public uint? SessionExpiryInterval { get; set; }

+        /// <summary>
+        /// Gets or sets a value indicating whether the subscription identifiers are available or not.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public bool? SubscriptionIdentifiersAvailable { get; set; }

+        /// <summary>
+        /// Gets or sets a value indicating whether the shared subscriptions are available or not.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public bool? SharedSubscriptionAvailable { get; set; }

+        /// <summary>
+        /// Gets or sets the user properties.
+        /// In MQTT 5, user properties are basic UTF-8 string key-value pairs that you can append to almost every type of MQTT packet.
+        /// As long as you don’t exceed the maximum message size, you can use an unlimited number of user properties to add metadata to MQTT messages and pass information between publisher, broker, and subscriber.
+        /// The feature is very similar to the HTTP header concept.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public List<MqttUserProperty> UserProperties { get; set; }
    }
 }
@@ -9,6 +9,10 @@ namespace MQTTnet.Client.Connecting
            AuthenticateResult = authenticateResult ?? throw new ArgumentNullException(nameof(authenticateResult));
        }

+        /// <summary>
+        /// Gets the authentication result.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public MqttClientAuthenticateResult AuthenticateResult { get; }
    }
 }
@@ -1,9 +1,17 @@
 namespace MQTTnet.Client.Disconnecting
 {
-    public class MqttClientDisconnectOptions
+    public sealed class MqttClientDisconnectOptions
    {
+        /// <summary>
+        /// Gets or sets the reason code.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public MqttClientDisconnectReason ReasonCode { get; set; } = MqttClientDisconnectReason.NormalDisconnection;

+        /// <summary>
+        /// Gets or sets the reason string.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public string ReasonString { get; set; }
    }
 }
@@ -3,6 +3,34 @@
    public enum MqttClientDisconnectReason
    {
        NormalDisconnection = 0,
-
+        DisconnectWithWillMessage = 4,
+        UnspecifiedError = 128,
+        MalformedPacket = 129,
+        ProtocolError = 130,
+        ImplementationSpecificError = 131,
+        NotAuthorized = 135,
+        ServerBusy = 137,
+        ServerShuttingDown = 139,
+        BadAuthenticationMethod = 140,
+        KeepaliveTimeout = 141,
+        SessionTakenOver = 142,
+        TopicFilterInvalid = 143,
+        TopicNameInvalid = 144,
+        ReceiveMaximumExceeded = 147,
+        TopicAliasInvalid = 148,
+        PacketTooLarge = 149,
+        MessageRateTooHigh = 150,
+        QuotaExceeded = 151,
+        AdministrativeAction = 152,
+        PayloadFormatInvalid = 153,
+        RetainNotSupported = 154,
+        QosNotSupported = 155,
+        UseAnotherServer = 156,
+        ServerMoved = 157,
+        SharedSubscriptionsNotSupported = 158,
+        ConnectionRateExceeded = 159,
+        MaximumConnectTime = 160,
+        SubscriptionIdentifiersNotSupported = 161,
+        WildcardSubscriptionsNotSupported = 162
    }
 }
@@ -3,19 +3,35 @@ using MQTTnet.Client.Connecting;

 namespace MQTTnet.Client.Disconnecting
 {
-    public class MqttClientDisconnectedEventArgs : EventArgs
+    public sealed class MqttClientDisconnectedEventArgs : EventArgs
    {
-        public MqttClientDisconnectedEventArgs(bool clientWasConnected, Exception exception, MqttClientAuthenticateResult authenticateResult)
+        public MqttClientDisconnectedEventArgs(bool clientWasConnected, Exception exception, MqttClientAuthenticateResult authenticateResult, MqttClientDisconnectReason reason)
        {
            ClientWasConnected = clientWasConnected;
            Exception = exception;
            AuthenticateResult = authenticateResult;
+            Reason = reason;
+
+            ReasonCode = reason;
        }

        public bool ClientWasConnected { get; }

        public Exception Exception { get; }

+        /// <summary>
+        /// Gets the authentication result.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public MqttClientAuthenticateResult AuthenticateResult { get; }
+
+        /// <summary>
+        /// Gets or sets the reason.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
+        public MqttClientDisconnectReason Reason { get; set; }
+
+        [Obsolete("Please use 'Reason' instead. This property will be removed in the future!")]
+        public MqttClientDisconnectReason ReasonCode { get; set; }
    }
 }
@@ -20,14 +20,37 @@ namespace MQTTnet.Client.ExtendedAuthenticationExchange
            Client = client ?? throw new ArgumentNullException(nameof(client));
        }

+        /// <summary>
+        /// Gets the reason code.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public MqttAuthenticateReasonCode ReasonCode { get; }

+        /// <summary>
+        /// Gets the reason string.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public string ReasonString { get; }

+        /// <summary>
+        /// Gets the authentication method.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public string AuthenticationMethod { get; }

+        /// <summary>
+        /// Gets the authentication data.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public byte[] AuthenticationData { get; }

+        /// <summary>
+        /// Gets the user properties.
+        /// In MQTT 5, user properties are basic UTF-8 string key-value pairs that you can append to almost every type of MQTT packet.
+        /// As long as you don’t exceed the maximum message size, you can use an unlimited number of user properties to add metadata to MQTT messages and pass information between publisher, broker, and subscriber.
+        /// The feature is very similar to the HTTP header concept.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public List<MqttUserProperty> UserProperties { get; }

        public IMqttClient Client { get; }
@@ -6,12 +6,33 @@ namespace MQTTnet.Client.ExtendedAuthenticationExchange
 {
    public class MqttExtendedAuthenticationExchangeData
    {
+        /// <summary>
+        /// Gets or sets the reason code.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public MqttAuthenticateReasonCode ReasonCode { get; set; }

+        /// <summary>
+        /// Gets or sets the reason string.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public string ReasonString { get; set; }

+        /// <summary>
+        /// Gets or sets the authentication data.
+        /// Authentication data is binary information used to transmit multiple iterations of cryptographic secrets of protocol steps.
+        /// The content of the authentication data is highly dependent on the specific implementation of the authentication method.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public byte[] AuthenticationData { get; set; }

+        /// <summary>
+        /// Gets or sets the user properties.
+        /// In MQTT 5, user properties are basic UTF-8 string key-value pairs that you can append to almost every type of MQTT packet.
+        /// As long as you don’t exceed the maximum message size, you can use an unlimited number of user properties to add metadata to MQTT messages and pass information between publisher, broker, and subscriber.
+        /// The feature is very similar to the HTTP header concept.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public List<MqttUserProperty> UserProperties { get; }
    }
 }
@@ -13,18 +13,38 @@ namespace MQTTnet.Client
    public interface IMqttClient : IApplicationMessageReceiver, IApplicationMessagePublisher, IDisposable
    {
        bool IsConnected { get; }
+
        IMqttClientOptions Options { get; }

+        /// <summary>
+        /// Gets or sets the connected handler that is fired after the client has connected to the server successfully.
+        /// Hint: Initialize handlers before you connect the client to avoid issues.
+        /// </summary>
        IMqttClientConnectedHandler ConnectedHandler { get; set; }

+        /// <summary>
+        /// Gets or sets the disconnected handler that is fired after the client has disconnected from the server.
+        /// Hint: Initialize handlers before you connect the client to avoid issues.
+        /// </summary>
        IMqttClientDisconnectedHandler DisconnectedHandler { get; set; }

        Task<MqttClientAuthenticateResult> ConnectAsync(IMqttClientOptions options, CancellationToken cancellationToken);
+
        Task DisconnectAsync(MqttClientDisconnectOptions options, CancellationToken cancellationToken);
+
        Task PingAsync(CancellationToken cancellationToken);

+        /// <summary>
+        /// Sends extended authentication data.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
+        /// <param name="data">The extended data.</param>
+        /// <param name="cancellationToken">A cancellation token to stop the task.</param>
+        /// <returns>A <see cref="Task"/> representing any asynchronous operation.</returns>
        Task SendExtendedAuthenticationExchangeDataAsync(MqttExtendedAuthenticationExchangeData data, CancellationToken cancellationToken);
+
        Task<MqttClientSubscribeResult> SubscribeAsync(MqttClientSubscribeOptions options, CancellationToken cancellationToken);
+
        Task<MqttClientUnsubscribeResult> UnsubscribeAsync(MqttClientUnsubscribeOptions options, CancellationToken cancellationToken);
    }
 }
@@ -1,5 +1,6 @@
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
+using MQTTnet.LowLevelClient;

 namespace MQTTnet.Client
 {
@@ -7,6 +8,14 @@ namespace MQTTnet.Client
    {
        IMqttFactory UseClientAdapterFactory(IMqttClientAdapterFactory clientAdapterFactory);

+        ILowLevelMqttClient CreateLowLevelMqttClient();
+
+        ILowLevelMqttClient CreateLowLevelMqttClient(IMqttNetLogger logger);
+
+        ILowLevelMqttClient CreateLowLevelMqttClient(IMqttClientAdapterFactory clientAdapterFactory);
+
+        ILowLevelMqttClient CreateLowLevelMqttClient(IMqttNetLogger logger, IMqttClientAdapterFactory clientAdapterFactory);
+
        IMqttClient CreateMqttClient();

        IMqttClient CreateMqttClient(IMqttNetLogger logger);
@@ -17,6 +17,7 @@ using System;
 using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Implementations;

 namespace MQTTnet.Client
 {
@@ -42,6 +43,7 @@ namespace MQTTnet.Client
        bool _cleanDisconnectInitiated;
        long _isDisconnectPending;
        bool _isConnected;
+        MqttClientDisconnectReason _disconnectReason;

        public MqttClient(IMqttClientAdapterFactory channelFactory, IMqttNetLogger logger)
        {
@@ -57,13 +59,7 @@ namespace MQTTnet.Client

        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler { get; set; }

-        public bool IsConnected
-        {
-            get
-            {
-                return _isConnected && Interlocked.Read(ref _isDisconnectPending) == 0;
-            }
-        }
+        public bool IsConnected => _isConnected && Interlocked.Read(ref _isDisconnectPending) == 0;

        public IMqttClientOptions Options { get; private set; }

@@ -83,7 +79,7 @@ namespace MQTTnet.Client
                Options = options;

                _packetIdentifierProvider.Reset();
-                _packetDispatcher.Reset();
+                _packetDispatcher.Cancel();

                _backgroundCancellationTokenSource = new CancellationTokenSource();
                var backgroundCancellationToken = _backgroundCancellationTokenSource.Token;
@@ -94,8 +90,8 @@ namespace MQTTnet.Client

                using (var combined = CancellationTokenSource.CreateLinkedTokenSource(backgroundCancellationToken, cancellationToken))
                {
-                    _logger.Verbose($"Trying to connect with server '{options.ChannelOptions}' (Timeout={options.CommunicationTimeout}).");
-                    await _adapter.ConnectAsync(options.CommunicationTimeout, combined.Token).ConfigureAwait(false);
+                    _logger.Verbose("Trying to connect with server '{0}' (Timeout={1}).", options.ChannelOptions, options.CommunicationTimeout);
+                    await adapter.ConnectAsync(options.CommunicationTimeout, combined.Token).ConfigureAwait(false);
                    _logger.Verbose("Connection with server established.");

                    _publishPacketReceiverQueue = new AsyncQueue<MqttPublishPacket>();
@@ -128,6 +124,8 @@ namespace MQTTnet.Client
            }
            catch (Exception exception)
            {
+                _disconnectReason = MqttClientDisconnectReason.UnspecifiedError;
+
                _logger.Error(exception, "Error while connecting with server.");

                if (!DisconnectIsPending())
@@ -145,11 +143,17 @@ namespace MQTTnet.Client

            ThrowIfDisposed();

+            if (DisconnectIsPending())
+            {
+                return;
+            }
+
            try
            {
+                _disconnectReason = MqttClientDisconnectReason.NormalDisconnection;
                _cleanDisconnectInitiated = true;

-                if (IsConnected)
+                if (_isConnected)
                {
                    var disconnectPacket = _adapter.PacketFormatterAdapter.DataConverter.CreateDisconnectPacket(options);
                    await SendAsync(disconnectPacket, cancellationToken).ConfigureAwait(false);
@@ -157,16 +161,13 @@ namespace MQTTnet.Client
            }
            finally
            {
-                if (!DisconnectIsPending())
-                {
-                    await DisconnectInternalAsync(null, null, null).ConfigureAwait(false);
-                }
+                await DisconnectInternalAsync(null, null, null).ConfigureAwait(false);
            }
        }

-        public async Task PingAsync(CancellationToken cancellationToken)
+        public Task PingAsync(CancellationToken cancellationToken)
        {
-            await SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket(), cancellationToken).ConfigureAwait(false);
+            return SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket(), cancellationToken);
        }

        public Task SendExtendedAuthenticationExchangeDataAsync(MqttExtendedAuthenticationExchangeData data, CancellationToken cancellationToken)
@@ -219,9 +220,9 @@ namespace MQTTnet.Client

        public Task<MqttClientPublishResult> PublishAsync(MqttApplicationMessage applicationMessage, CancellationToken cancellationToken)
        {
-            if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
+            cancellationToken.ThrowIfCancellationRequested();

-            MqttTopicValidator.ThrowIfInvalid(applicationMessage.Topic);
+            MqttTopicValidator.ThrowIfInvalid(applicationMessage);

            ThrowIfDisposed();
            ThrowIfNotConnected();
@@ -251,24 +252,27 @@ namespace MQTTnet.Client

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

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

-            _adapter?.Dispose();
+                _adapter?.Dispose();
+            }
        }

-
        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                Cleanup();
-
-                DisconnectedHandler = null;
            }

            base.Dispose(disposing);
@@ -308,7 +312,7 @@ namespace MQTTnet.Client

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

            TryInitiateDisconnect();
            _isConnected = false;
@@ -354,7 +358,7 @@ namespace MQTTnet.Client
                {
                    // 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);
+                    Task.Run(() => disconnectedHandler.HandleDisconnectedAsync(new MqttClientDisconnectedEventArgs(clientWasConnected, exception, authenticateResult, _disconnectReason))).RunInBackground(_logger);
                }
            }
        }
@@ -365,11 +369,6 @@ namespace MQTTnet.Client
            {
                try
                {
-                    if (_backgroundCancellationTokenSource?.IsCancellationRequested == true)
-                    {
-                        return;
-                    }
-
                    _backgroundCancellationTokenSource?.Cancel(false);
                }
                catch (Exception exception)
@@ -385,17 +384,17 @@ namespace MQTTnet.Client

            _sendTracker.Restart();

-            return _adapter.SendPacketAsync(packet, Options.CommunicationTimeout, cancellationToken);
+            return _adapter.SendPacketAsync(packet, cancellationToken);
        }

        async Task<TResponsePacket> SendAndReceiveAsync<TResponsePacket>(MqttBasePacket requestPacket, CancellationToken cancellationToken) where TResponsePacket : MqttBasePacket
        {
            cancellationToken.ThrowIfCancellationRequested();
-            
+
            ushort identifier = 0;
-            if (requestPacket is IMqttPacketWithIdentifier packetWithIdentifier && packetWithIdentifier.PacketIdentifier.HasValue)
+            if (requestPacket is IMqttPacketWithIdentifier packetWithIdentifier && packetWithIdentifier.PacketIdentifier > 0)
            {
-                identifier = packetWithIdentifier.PacketIdentifier.Value;
+                identifier = packetWithIdentifier.PacketIdentifier;
            }

            using (var packetAwaiter = _packetDispatcher.AddAwaiter<TResponsePacket>(identifier))
@@ -403,12 +402,11 @@ namespace MQTTnet.Client
                try
                {
                    _sendTracker.Restart();
-
-                    await _adapter.SendPacketAsync(requestPacket, Options.CommunicationTimeout, cancellationToken).ConfigureAwait(false);
+                    await _adapter.SendPacketAsync(requestPacket, cancellationToken).ConfigureAwait(false);
                }
                catch (Exception e)
                {
-                    _logger.Warning(e, "Error when sending packet of type '{0}'.", typeof(TResponsePacket).Name);
+                    _logger.Warning(e, "Error when sending request packet ({0}).", requestPacket.GetType().Name);
                    packetAwaiter.Cancel();
                }

@@ -420,7 +418,7 @@ namespace MQTTnet.Client
                {
                    if (exception is MqttCommunicationTimedOutException)
                    {
-                        _logger.Warning(null, "Timeout while waiting for packet of type '{0}'.", typeof(TResponsePacket).Name);
+                        _logger.Warning(null, "Timeout while waiting for response packet ({0}).", typeof(TResponsePacket).Name);
                    }

                    throw;
@@ -440,13 +438,17 @@ namespace MQTTnet.Client
                {
                    // Values described here: [MQTT-3.1.2-24].
                    var waitTime = keepAlivePeriod - _sendTracker.Elapsed;
-                    
+
                    if (waitTime <= TimeSpan.Zero)
                    {
-                        await SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket(), cancellationToken).ConfigureAwait(false);
+                        await SendAndReceiveAsync<MqttPingRespPacket>(MqttPingReqPacket.Instance, cancellationToken).ConfigureAwait(false);
                    }

-                    await Task.Delay(keepAlivePeriod, cancellationToken).ConfigureAwait(false);
+                    // Wait a fixed time in all cases. Calculation of the remaining time is complicated
+                    // due to some edge cases and was buggy in the past. Now we wait half a second because the
+                    // min keep alive value is one second so that the server will wait 1.5 seconds for a PING
+                    // packet.
+                    await Task.Delay(TimeSpan.FromMilliseconds(100), cancellationToken).ConfigureAwait(false);
                }
            }
            catch (Exception exception)
@@ -458,6 +460,7 @@ namespace MQTTnet.Client

                if (exception is OperationCanceledException)
                {
+                    return;
                }
                else if (exception is MqttCommunicationException)
                {
@@ -487,7 +490,7 @@ namespace MQTTnet.Client

                while (!cancellationToken.IsCancellationRequested)
                {
-                    var packet = await _adapter.ReceivePacketAsync(TimeSpan.Zero, cancellationToken).ConfigureAwait(false);
+                    var packet = await _adapter.ReceivePacketAsync(cancellationToken).ConfigureAwait(false);

                    if (cancellationToken.IsCancellationRequested)
                    {
@@ -549,32 +552,25 @@ namespace MQTTnet.Client
                {
                    EnqueueReceivedPublishPacket(publishPacket);
                }
+                else if (packet is MqttPubRecPacket pubRecPacket)
+                {
+                    await ProcessReceivedPubRecPacket(pubRecPacket, cancellationToken).ConfigureAwait(false);
+                }
                else if (packet is MqttPubRelPacket pubRelPacket)
                {
-                    await SendAsync(new MqttPubCompPacket
-                    {
-                        PacketIdentifier = pubRelPacket.PacketIdentifier,
-                        ReasonCode = MqttPubCompReasonCode.Success
-                    }, cancellationToken).ConfigureAwait(false);
+                    await ProcessReceivedPubRelPacket(pubRelPacket, cancellationToken).ConfigureAwait(false);
                }
                else if (packet is MqttPingReqPacket)
                {
-                    await SendAsync(new MqttPingRespPacket(), cancellationToken).ConfigureAwait(false);
+                    await SendAsync(MqttPingRespPacket.Instance, cancellationToken).ConfigureAwait(false);
                }
-                else if (packet is MqttDisconnectPacket)
+                else if (packet is MqttDisconnectPacket disconnectPacket)
                {
-                    // Also dispatch disconnect to waiting threads to generate a proper exception.
-                    _packetDispatcher.Dispatch(packet);
-
-                    await DisconnectAsync(null, cancellationToken).ConfigureAwait(false);
+                    await ProcessReceivedDisconnectPacket(disconnectPacket).ConfigureAwait(false);
                }
                else if (packet is MqttAuthPacket authPacket)
                {
-                    var extendedAuthenticationExchangeHandler = Options.ExtendedAuthenticationExchangeHandler;
-                    if (extendedAuthenticationExchangeHandler != null)
-                    {
-                        await extendedAuthenticationExchangeHandler.HandleRequestAsync(new MqttExtendedAuthenticationExchangeContext(authPacket, this)).ConfigureAwait(false);
-                    }
+                    await ProcessReceivedAuthPacket(authPacket).ConfigureAwait(false);
                }
                else
                {
@@ -617,7 +613,7 @@ namespace MQTTnet.Client
            }
            catch (Exception exception)
            {
-                _logger.Error(exception, "Error while enqueueing application message.");
+                _logger.Error(exception, "Error while queueing application message.");
            }
        }

@@ -627,8 +623,7 @@ namespace MQTTnet.Client
            {
                try
                {
-                    var publishPacketDequeueResult = await _publishPacketReceiverQueue.TryDequeueAsync(cancellationToken);
-
+                    var publishPacketDequeueResult = await _publishPacketReceiverQueue.TryDequeueAsync(cancellationToken).ConfigureAwait(false);
                    if (!publishPacketDequeueResult.IsSuccess)
                    {
                        return;
@@ -642,26 +637,28 @@ namespace MQTTnet.Client
                    }
                    else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtLeastOnce)
                    {
-                        if (await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false))
+                        var eventArgs = await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false);
+
+                        if (!eventArgs.ProcessingFailed)
                        {
                            await SendAsync(new MqttPubAckPacket
                            {
                                PacketIdentifier = publishPacket.PacketIdentifier,
-                                ReasonCode = MqttPubAckReasonCode.Success
+                                ReasonCode = (MqttPubAckReasonCode)eventArgs.ReasonCode
                            }, cancellationToken).ConfigureAwait(false);
                        }
                    }
                    else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.ExactlyOnce)
                    {
-                        if (await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false))
+                        var eventArgs = await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false);
+
+                        if (!eventArgs.ProcessingFailed)
                        {
-                            var pubRecPacket = new MqttPubRecPacket
+                            await SendAsync(new MqttPubRecPacket
                            {
                                PacketIdentifier = publishPacket.PacketIdentifier,
-                                ReasonCode = MqttPubRecReasonCode.Success
-                            };
-
-                            await SendAsync(pubRecPacket, cancellationToken).ConfigureAwait(false);
+                                ReasonCode = (MqttPubRecReasonCode)eventArgs.ReasonCode
+                            }, cancellationToken).ConfigureAwait(false);
                        }
                    }
                    else
@@ -669,6 +666,9 @@ namespace MQTTnet.Client
                        throw new MqttProtocolViolationException("Received a not supported QoS level.");
                    }
                }
+                catch (OperationCanceledException)
+                {
+                }
                catch (Exception exception)
                {
                    _logger.Error(exception, "Error while handling application message.");
@@ -676,6 +676,57 @@ namespace MQTTnet.Client
            }
        }

+        Task ProcessReceivedPubRecPacket(MqttPubRecPacket pubRecPacket, CancellationToken cancellationToken)
+        {
+            if (!_packetDispatcher.TryDispatch(pubRecPacket))
+            {
+                // The packet is unknown. Probably due to a restart of the client.
+                // So wen send this to the server to trigger a full resend of the message.
+                return SendAsync(new MqttPubRelPacket
+                {
+                    PacketIdentifier = pubRecPacket.PacketIdentifier,
+                    ReasonCode = MqttPubRelReasonCode.PacketIdentifierNotFound
+                }, cancellationToken);
+            }
+
+            return PlatformAbstractionLayer.CompletedTask;
+        }
+
+        Task ProcessReceivedPubRelPacket(MqttPubRelPacket pubRelPacket, CancellationToken cancellationToken)
+        {
+            return SendAsync(new MqttPubCompPacket
+            {
+                PacketIdentifier = pubRelPacket.PacketIdentifier,
+                ReasonCode = MqttPubCompReasonCode.Success
+            }, cancellationToken);
+        }
+
+        Task ProcessReceivedDisconnectPacket(MqttDisconnectPacket disconnectPacket)
+        {
+            _disconnectReason = (MqttClientDisconnectReason)(disconnectPacket.ReasonCode ?? MqttDisconnectReasonCode.NormalDisconnection);
+
+            // Also dispatch disconnect to waiting threads to generate a proper exception.
+            _packetDispatcher.Dispatch(disconnectPacket);
+
+            if (!DisconnectIsPending())
+            {
+                return DisconnectInternalAsync(_packetReceiverTask, null, null);
+            }
+
+            return PlatformAbstractionLayer.CompletedTask;
+        }
+
+        Task ProcessReceivedAuthPacket(MqttAuthPacket authPacket)
+        {
+            var extendedAuthenticationExchangeHandler = Options.ExtendedAuthenticationExchangeHandler;
+            if (extendedAuthenticationExchangeHandler != null)
+            {
+                return extendedAuthenticationExchangeHandler.HandleRequestAsync(new MqttExtendedAuthenticationExchangeContext(authPacket, this));
+            }
+
+            return PlatformAbstractionLayer.CompletedTask;
+        }
+
        async Task<MqttClientPublishResult> PublishAtMostOnce(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
        {
            // No packet identifier is used for QoS 0 [3.3.2.2 Packet Identifier]
@@ -707,19 +758,18 @@ namespace MQTTnet.Client
            return _adapter.PacketFormatterAdapter.DataConverter.CreatePublishResult(pubRecPacket, pubCompPacket);
        }

-        async Task<bool> HandleReceivedApplicationMessageAsync(MqttPublishPacket publishPacket)
+        async Task<MqttApplicationMessageReceivedEventArgs> HandleReceivedApplicationMessageAsync(MqttPublishPacket publishPacket)
        {
            var applicationMessage = _adapter.PacketFormatterAdapter.DataConverter.CreateApplicationMessage(publishPacket);
+            var eventArgs = new MqttApplicationMessageReceivedEventArgs(Options.ClientId, applicationMessage);

            var handler = ApplicationMessageReceivedHandler;
            if (handler != null)
            {
-                var eventArgs = new MqttApplicationMessageReceivedEventArgs(Options.ClientId, applicationMessage);
                await handler.HandleApplicationMessageReceivedAsync(eventArgs).ConfigureAwait(false);
-                return !eventArgs.ProcessingFailed;
            }

-            return true;
+            return eventArgs;
        }

        async Task WaitForTaskAsync(Task task, Task sender)
@@ -755,6 +805,8 @@ namespace MQTTnet.Client

        bool DisconnectIsPending()
        {
+            // This will read the _isDisconnectPending and set it to "1" afterwards regardless of the value.
+            // So the first caller will get a "false" and all subsequent ones will get "true".
            return Interlocked.CompareExchange(ref _isDisconnectPending, 1, 0) != 0;
        }
    }
@@ -128,7 +128,21 @@ namespace MQTTnet.Client
        {
            if (client == null) throw new ArgumentNullException(nameof(client));

-            return client.DisconnectAsync(new MqttClientDisconnectOptions());
+            return client.DisconnectAsync(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 DisconnectAsync(this IMqttClient client, CancellationToken cancellationToken)
+        {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+
+            return client.DisconnectAsync(new MqttClientDisconnectOptions(), cancellationToken);
        }

        public static Task<MqttClientSubscribeResult> SubscribeAsync(this IMqttClient client, params MqttTopicFilter[] topicFilters)
@@ -176,13 +190,6 @@ namespace MQTTnet.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));
@@ -1,9 +1,10 @@
 namespace MQTTnet.Client
 {
-    public class MqttPacketIdentifierProvider
+    public sealed class MqttPacketIdentifierProvider
    {
-        private readonly object _syncRoot = new object();
-        private ushort _value;
+        readonly object _syncRoot = new object();
+
+        ushort _value;

        public void Reset()
        {
@@ -3,31 +3,112 @@ using MQTTnet.Formatter;
 using MQTTnet.Packets;
 using System;
 using System.Collections.Generic;
+using MQTTnet.Diagnostics.PacketInspection;

 namespace MQTTnet.Client.Options
 {
    public interface IMqttClientOptions
    {
+        /// <summary>
+        /// Gets the client identifier.
+        /// Hint: This identifier needs to be unique over all used clients / devices on the broker to avoid connection issues.
+        /// </summary>
        string ClientId { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether clean sessions are used or not.
+        /// When a client connects to a broker it can connect using either a non persistent connection (clean session) or a persistent connection.
+        /// With a non persistent connection the broker doesn't store any subscription information or undelivered messages for the client.
+        /// This mode is ideal when the client only publishes messages.
+        /// It can also connect as a durable client using a persistent connection.
+        /// In this mode, the broker will store subscription information, and undelivered messages for the client.
+        /// </summary>
        bool CleanSession { get; }
+
        IMqttClientCredentials Credentials { get; }
+
        IMqttExtendedAuthenticationExchangeHandler ExtendedAuthenticationExchangeHandler { get; }
+
        MqttProtocolVersion ProtocolVersion { get; }
+
        IMqttClientChannelOptions ChannelOptions { get; }

        TimeSpan CommunicationTimeout { get; }
+
+        /// <summary>
+        /// Gets the keep alive period.
+        /// The connection is normally left open by the client so that is can send and receive data at any time.
+        /// If no data flows over an open connection for a certain time period then the client will generate a PINGREQ and expect to receive a PINGRESP from the broker.
+        /// This message exchange confirms that the connection is open and working.
+        /// This period is known as the keep alive period. 
+        /// </summary>
        TimeSpan KeepAlivePeriod { get; }
+
+        /// <summary>
+        /// Gets the last will message.
+        /// In MQTT, you use the last will message feature to notify other clients about an ungracefully disconnected client.
+        /// </summary>
        MqttApplicationMessage WillMessage { get; }
+
+        /// <summary>
+        /// Gets the will delay interval.
+        /// This is the time between the client disconnect and the time the will message will be sent.
+        /// </summary>
        uint? WillDelayInterval { get; }

+        /// <summary>
+        /// Gets the authentication method.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        string AuthenticationMethod { get; }
+
+        /// <summary>
+        /// Gets the authentication data.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        byte[] AuthenticationData { get; }
+
        uint? MaximumPacketSize { get; }
+
+        /// <summary>
+        /// Gets the receive maximum.
+        /// This gives the maximum length of the receive messages.
+        /// </summary>
        ushort? ReceiveMaximum { get; }
+
+        /// <summary>
+        /// Gets the request problem information.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        bool? RequestProblemInformation { get; }
+
+        /// <summary>
+        /// Gets the request response information.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        bool? RequestResponseInformation { get; }
+
+        /// <summary>
+        /// Gets the session expiry interval.
+        /// The time after a session expires when it's not actively used.
+        /// </summary>
        uint? SessionExpiryInterval { get; }
+
+        /// <summary>
+        /// Gets the topic alias maximum.
+        /// This gives the maximum length of the topic alias.
+        /// </summary>
        ushort? TopicAliasMaximum { get; }
+
+        /// <summary>
+        /// Gets or sets the user properties.
+        /// In MQTT 5, user properties are basic UTF-8 string key-value pairs that you can append to almost every type of MQTT packet.
+        /// As long as you don’t exceed the maximum message size, you can use an unlimited number of user properties to add metadata to MQTT messages and pass information between publisher, broker, and subscriber.
+        /// The feature is very similar to the HTTP header concept.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        List<MqttUserProperty> UserProperties { get; set; }
+
+        IMqttPacketInspector PacketInspector { get; set; }
    }
 }
@@ -3,33 +3,112 @@ using MQTTnet.Formatter;
 using MQTTnet.Packets;
 using System;
 using System.Collections.Generic;
+using MQTTnet.Diagnostics.PacketInspection;

 namespace MQTTnet.Client.Options
 {
    public class MqttClientOptions : IMqttClientOptions
    {
+        /// <summary>
+        /// Gets the client identifier.
+        /// Hint: This identifier needs to be unique over all used clients / devices on the broker to avoid connection issues.
+        /// </summary>
        public string ClientId { get; set; } = Guid.NewGuid().ToString("N");
+
+        /// <summary>
+        /// Gets or sets a value indicating whether clean sessions are used or not.
+        /// When a client connects to a broker it can connect using either a non persistent connection (clean session) or a persistent connection.
+        /// With a non persistent connection the broker doesn't store any subscription information or undelivered messages for the client.
+        /// This mode is ideal when the client only publishes messages.
+        /// It can also connect as a durable client using a persistent connection.
+        /// In this mode, the broker will store subscription information, and undelivered messages for the client.
+        /// </summary>
        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; }
+
        public TimeSpan CommunicationTimeout { get; set; } = TimeSpan.FromSeconds(10);
+
+        /// <summary>
+        /// Gets or sets the keep alive period.
+        /// The connection is normally left open by the client so that is can send and receive data at any time.
+        /// If no data flows over an open connection for a certain time period then the client will generate a PINGREQ and expect to receive a PINGRESP from the broker.
+        /// This message exchange confirms that the connection is open and working.
+        /// This period is known as the keep alive period. 
+        /// </summary>
        public TimeSpan KeepAlivePeriod { get; set; } = TimeSpan.FromSeconds(15);

+        /// <summary>
+        /// Gets or sets the last will message.
+        /// In MQTT, you use the last will message feature to notify other clients about an ungracefully disconnected client.
+        /// </summary>
        public MqttApplicationMessage WillMessage { get; set; }
+
+        /// <summary>
+        /// Gets or sets the will delay interval.
+        /// This is the time between the client disconnect and the time the will message will be sent.
+        /// </summary>
        public uint? WillDelayInterval { get; set; }

+        /// <summary>
+        /// Gets or sets the authentication method.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public string AuthenticationMethod { get; set; }
+
+        /// <summary>
+        /// Gets or sets the authentication data.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public byte[] AuthenticationData { get; set; }

        public uint? MaximumPacketSize { get; set; }
+
+        /// <summary>
+        /// Gets or sets the receive maximum.
+        /// This gives the maximum length of the receive messages.
+        /// </summary>
        public ushort? ReceiveMaximum { get; set; }
+
+        /// <summary>
+        /// Gets or sets the request problem information.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public bool? RequestProblemInformation { get; set; }
+
+        /// <summary>
+        /// Gets or sets the request response information.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public bool? RequestResponseInformation { get; set; }
+
+        /// <summary>
+        /// Gets or sets the session expiry interval.
+        /// The time after a session expires when it's not actively used.
+        /// </summary>
        public uint? SessionExpiryInterval { get; set; }
+
+        /// <summary>
+        /// Gets or sets the topic alias maximum.
+        /// This gives the maximum length of the topic alias.
+        /// </summary>
        public ushort? TopicAliasMaximum { get; set; }
+
+        /// <summary>
+        /// Gets or sets the user properties.
+        /// In MQTT 5, user properties are basic UTF-8 string key-value pairs that you can append to almost every type of MQTT packet.
+        /// As long as you don’t exceed the maximum message size, you can use an unlimited number of user properties to add metadata to MQTT messages and pass information between publisher, broker, and subscriber.
+        /// The feature is very similar to the HTTP header concept.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public List<MqttUserProperty> UserProperties { get; set; }
+
+        public IMqttPacketInspector PacketInspector { get; set; }
    }
 }
@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
+using MQTTnet.Diagnostics.PacketInspection;

 namespace MQTTnet.Client.Options
 {
@@ -256,6 +257,12 @@ namespace MQTTnet.Client.Options
            return this;
        }

+        public MqttClientOptionsBuilder WithPacketInspector(IMqttPacketInspector packetInspector)
+        {
+            _options.PacketInspector = packetInspector;
+            return this;
+        }
+
        public IMqttClientOptions Build()
        {
            if (_tcpOptions == null && _webSocketOptions == null)
@@ -280,7 +287,9 @@ namespace MQTTnet.Client.Options
 #pragma warning disable CS0618 // Type or member is obsolete
                        CertificateValidationCallback = _tlsParameters.CertificateValidationCallback,
 #pragma warning restore CS0618 // Type or member is obsolete
-
+#if NETCOREAPP3_1
+                        ApplicationProtocols = _tlsParameters.ApplicationProtocols,
+#endif
                        CertificateValidationHandler = _tlsParameters.CertificateValidationHandler,
                        IgnoreCertificateChainErrors = _tlsParameters.IgnoreCertificateChainErrors,
                        IgnoreCertificateRevocationErrors = _tlsParameters.IgnoreCertificateRevocationErrors
@@ -19,7 +19,11 @@ namespace MQTTnet.Client.Options

        public Func<MqttClientCertificateValidationCallbackContext, bool> CertificateValidationHandler { get; set; }

+#if NETCOREAPP3_1 || NET5_0
+        public SslProtocols SslProtocol { get; set; } = SslProtocols.Tls13;
+#else
        public SslProtocols SslProtocol { get; set; } = SslProtocols.Tls12;
+#endif

 #if WINDOWS_UWP
        public IEnumerable<IEnumerable<byte>> Certificates { get; set; }
@@ -27,7 +31,11 @@ namespace MQTTnet.Client.Options
        public IEnumerable<X509Certificate> Certificates { get; set; }
 #endif

-        public bool AllowUntrustedCertificates { get; set; }
+#if NETCOREAPP3_1
+	    public List<SslApplicationProtocol> ApplicationProtocols { get;set; }
+#endif 
+
+	    public bool AllowUntrustedCertificates { get; set; }

        public bool IgnoreCertificateChainErrors { get; set; }

@@ -8,7 +8,7 @@ namespace MQTTnet.Client.Options

        public int? Port { get; set; }

-        public int BufferSize { get; set; } = 65536;
+        public int BufferSize { get; set; } = 8192;

        public bool? DualMode { get; set; }

@@ -22,7 +22,15 @@ namespace MQTTnet.Client.Options
        public List<X509Certificate> Certificates { get; set; }
 #endif

+#if NETCOREAPP3_1
+        public List<SslApplicationProtocol> ApplicationProtocols { get; set; }
+#endif
+
+#if NETCOREAPP3_1 || NET5_0
+        public SslProtocols SslProtocol { get; set; } = SslProtocols.Tls13;
+#else
        public SslProtocols SslProtocol { get; set; } = SslProtocols.Tls12;
+#endif

        [Obsolete("This property will be removed soon. Use CertificateValidationHandler instead.")]
        public Func<X509Certificate, X509Chain, SslPolicyErrors, IMqttClientOptions, bool> CertificateValidationCallback { get; set; }
@@ -8,10 +8,25 @@ namespace MQTTnet.Client.Publishing
    {
        public ushort? PacketIdentifier { get; set; }

+        /// <summary>
+        /// Gets or sets the reason code.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public MqttClientPublishReasonCode ReasonCode { get; set; } = MqttClientPublishReasonCode.Success;

+        /// <summary>
+        /// Gets or sets the reason string.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public string ReasonString { get; set; }

+        /// <summary>
+        /// Gets or sets the user properties.
+        /// In MQTT 5, user properties are basic UTF-8 string key-value pairs that you can append to almost every type of MQTT packet.
+        /// As long as you don’t exceed the maximum message size, you can use an unlimited number of user properties to add metadata to MQTT messages and pass information between publisher, broker, and subscriber.
+        /// The feature is very similar to the HTTP header concept.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public List<MqttUserProperty> UserProperties { get; set; }
    }
 }
@@ -5,10 +5,28 @@ namespace MQTTnet.Client.Subscribing
 {
    public class MqttClientSubscribeOptions
    {
+        /// <summary>
+        /// Gets or sets a list of topic filters the client wants to subscribe to.
+        /// Topic filters can include regular topics or wild cards.
+        /// </summary>
        public List<MqttTopicFilter> TopicFilters { get; set; } = new List<MqttTopicFilter>();

+        /// <summary>
+        /// Gets or sets the subscription identifier.
+        /// The client can specify a subscription identifier when subscribing.
+        /// The broker will establish and store the mapping relationship between this subscription and subscription identifier when successfully create or modify subscription.
+        /// The broker will return the subscription identifier associated with this PUBLISH packet and the PUBLISH packet to the client when need to forward PUBLISH packets matching this subscription to this client.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public uint? SubscriptionIdentifier { get; set; }

+        /// <summary>
+        /// Gets or sets the user properties.
+        /// In MQTT 5, user properties are basic UTF-8 string key-value pairs that you can append to almost every type of MQTT packet.
+        /// As long as you don’t exceed the maximum message size, you can use an unlimited number of user properties to add metadata to MQTT messages and pass information between publisher, broker, and subscriber.
+        /// The feature is very similar to the HTTP header concept.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public List<MqttUserProperty> UserProperties { get; set; }
    }
 }
@@ -9,6 +9,13 @@ namespace MQTTnet.Client.Subscribing
    {
        private readonly MqttClientSubscribeOptions _subscribeOptions = new MqttClientSubscribeOptions();

+        /// <summary>
+        /// Adds the user property to the subscribe options.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
+        /// <param name="name">The property name.</param>
+        /// <param name="value">The property value.</param>
+        /// <returns>A new instance of the <see cref="MqttApplicationMessageBuilder"/> class.</returns>
        public MqttClientSubscribeOptionsBuilder WithUserProperty(string name, string value)
        {
            if (name == null) throw new ArgumentNullException(nameof(name));
@@ -27,7 +34,6 @@ namespace MQTTnet.Client.Subscribing
        public MqttClientSubscribeOptionsBuilder WithSubscriptionIdentifier(uint? subscriptionIdentifier)
        {
            _subscribeOptions.SubscriptionIdentifier = subscriptionIdentifier;
-
            return this;
        }

@@ -10,8 +10,16 @@ namespace MQTTnet.Client.Subscribing
            ResultCode = resultCode;
        }

+        /// <summary>
+        /// Gets or sets the topic filter.
+        /// The topic filter can contain topics and wildcards.
+        /// </summary>
        public MqttTopicFilter TopicFilter { get; }

+        /// <summary>
+        /// Gets or sets the result code.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public MqttClientSubscribeResultCode ResultCode { get; }
    }
 }
@@ -5,8 +5,19 @@ namespace MQTTnet.Client.Unsubscribing
 {
    public class MqttClientUnsubscribeOptions
    {
+        /// <summary>
+        /// Gets or sets a list of topic filters the client wants to unsubscribe from.
+        /// Topic filters can include regular topics or wild cards.
+        /// </summary>
        public List<string> TopicFilters { get; set; } = new List<string>();

+        /// <summary>
+        /// Gets or sets the user properties.
+        /// In MQTT 5, user properties are basic UTF-8 string key-value pairs that you can append to almost every type of MQTT packet.
+        /// As long as you don’t exceed the maximum message size, you can use an unlimited number of user properties to add metadata to MQTT messages and pass information between publisher, broker, and subscriber.
+        /// The feature is very similar to the HTTP header concept.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public List<MqttUserProperty> UserProperties { get; set; } = new List<MqttUserProperty>();
    }
 }
@@ -8,6 +8,13 @@ namespace MQTTnet.Client.Unsubscribing
    {
        private readonly MqttClientUnsubscribeOptions _unsubscribeOptions = new MqttClientUnsubscribeOptions();

+        /// <summary>
+        /// Adds the user property to the unsubscribe options.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
+        /// <param name="name">The property name.</param>
+        /// <param name="value">The property value.</param>
+        /// <returns>A new instance of the <see cref="MqttClientUnsubscribeOptionsBuilder"/> class.</returns>
        public MqttClientUnsubscribeOptionsBuilder WithUserProperty(string name, string value)
        {
            if (name is null) throw new ArgumentNullException(nameof(name));
@@ -16,6 +23,12 @@ namespace MQTTnet.Client.Unsubscribing
            return WithUserProperty(new MqttUserProperty(name, value));
        }

+        /// <summary>
+        /// Adds the user property to the unsubscribe options.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
+        /// <param name="userProperty">The user property.</param>
+        /// <returns>A new instance of the <see cref="MqttClientUnsubscribeOptionsBuilder"/> class.</returns>
        public MqttClientUnsubscribeOptionsBuilder WithUserProperty(MqttUserProperty userProperty)
        {
            if (userProperty is null) throw new ArgumentNullException(nameof(userProperty));
@@ -10,8 +10,16 @@ namespace MQTTnet.Client.Unsubscribing
            ReasonCode = reasonCode;
        }

+        /// <summary>
+        /// Gets or sets the topic filter.
+        /// The topic filter can contain topics and wildcards.
+        /// </summary>
        public string TopicFilter { get; }

+        /// <summary>
+        /// Gets or sets the result code.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
        public MqttClientUnsubscribeResultCode ReasonCode { get; }
    }
 }
@@ -4,8 +4,6 @@ namespace MQTTnet.Diagnostics
 {
    public interface IMqttNetLogger
    {
-        event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
-
        IMqttNetScopedLogger CreateScopedLogger(string source);

        void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception);
@@ -2,6 +2,7 @@

 namespace MQTTnet.Diagnostics
 {
+    [Obsolete("Please pass an instance of the IMqttNetLogger to the factory/server or client. The global logger will be deleted in the future.")]
    public static class MqttNetGlobalLogger
    {
        public static event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
@@ -10,8 +11,6 @@ namespace MQTTnet.Diagnostics

        public static void Publish(MqttNetLogMessage logMessage)
        {
-            if (logMessage == null) throw new ArgumentNullException(nameof(logMessage));
-
            LogMessagePublished?.Invoke(null, new MqttNetLogMessagePublishedEventArgs(logMessage));
        }
    }
@@ -2,7 +2,7 @@

 namespace MQTTnet.Diagnostics
 {
-    public class MqttNetLogMessage
+    public sealed class MqttNetLogMessage
    {
        public string LogId { get; set; }

@@ -2,18 +2,18 @@

 namespace MQTTnet.Diagnostics
 {
-    public class MqttNetLogMessagePublishedEventArgs : EventArgs
+    public sealed class MqttNetLogMessagePublishedEventArgs : EventArgs
    {
        public MqttNetLogMessagePublishedEventArgs(MqttNetLogMessage logMessage)
        {
            LogMessage = logMessage ?? throw new ArgumentNullException(nameof(logMessage));

 #pragma warning disable CS0618 // Type or member is obsolete
-            TraceMessage = logMessage ?? throw new ArgumentNullException(nameof(logMessage));
+            TraceMessage = logMessage;
 #pragma warning restore CS0618 // Type or member is obsolete
        }

-        [Obsolete("Use new proeprty LogMessage instead.")]
+        [Obsolete("Use new property LogMessage instead.")]
        public MqttNetLogMessage TraceMessage { get; }

        public MqttNetLogMessage LogMessage { get; }
@@ -36,13 +36,16 @@ namespace MQTTnet.Diagnostics
                return;
            }

-            try
+            if (parameters?.Length > 0 && message?.Length > 0)
            {
-                message = string.Format(message ?? string.Empty, parameters);
-            }
-            catch (FormatException)
-            {
-                message = "MESSAGE FORMAT INVALID: " + message;
+                try
+                {
+                    message = string.Format(message, parameters);
+                }
+                catch (FormatException)
+                {
+                    message = "MESSAGE FORMAT INVALID: " + message;
+                }
            }

            var logMessage = new MqttNetLogMessage
@@ -18,6 +18,11 @@ namespace MQTTnet.Diagnostics
        {
            logger.Publish(MqttNetLogLevel.Warning, message, parameters, exception);
        }
+        
+        public static void Warning(this IMqttNetScopedLogger logger, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Warning, message, parameters, null);
+        }

        public static void Error(this IMqttNetScopedLogger logger, Exception exception, string message, params object[] parameters)
        {
@@ -0,0 +1,7 @@
+namespace MQTTnet.Diagnostics.PacketInspection
+{
+    public interface IMqttPacketInspector
+    {
+        void ProcessMqttPacket(ProcessMqttPacketContext context);
+    }
+}
@@ -0,0 +1,9 @@
+namespace MQTTnet.Diagnostics.PacketInspection
+{
+    public enum MqttPacketFlowDirection
+    {
+        Inbound,
+
+        Outbound
+    }
+}
@@ -0,0 +1,9 @@
+namespace MQTTnet.Diagnostics.PacketInspection
+{
+    public sealed class ProcessMqttPacketContext
+    {
+        public MqttPacketFlowDirection Direction { get; set; }
+
+        public byte[] Buffer { get; set; }
+    }
+}
@@ -20,6 +20,10 @@
                return "netstandard2.1";
 #elif WINDOWS_UWP
                return "uap10.0";
+#elif NETCOREAPP3_1
+                return "netcoreapp3.1";
+#elif NET5_0
+                return "net5.0";
 #endif
            }
        }
@@ -13,8 +13,8 @@ namespace MQTTnet.Exceptions
        {
        }

-        public MqttCommunicationException(string message)
-            : base(message)
+        public MqttCommunicationException(string message, Exception innerException = null)
+            : base(message, innerException)
        {
        }
    }
@@ -1,10 +1,12 @@
-using MQTTnet.Client.Connecting;
+using System.Collections.Generic;
+using MQTTnet.Client.Connecting;
 using MQTTnet.Client.Disconnecting;
 using MQTTnet.Client.Options;
 using MQTTnet.Client.Publishing;
 using MQTTnet.Client.Subscribing;
 using MQTTnet.Client.Unsubscribing;
 using MQTTnet.Packets;
+using MQTTnet.Protocol;
 using MQTTnet.Server;
 using MqttClientSubscribeResult = MQTTnet.Client.Subscribing.MqttClientSubscribeResult;

@@ -16,6 +18,8 @@ namespace MQTTnet.Formatter

        MqttPubAckPacket CreatePubAckPacket(MqttPublishPacket publishPacket);

+        MqttBasePacket CreatePubRecPacket(MqttPublishPacket publishPacket);
+
        MqttApplicationMessage CreateApplicationMessage(MqttPublishPacket publishPacket);

        MqttClientAuthenticateResult CreateClientConnectResult(MqttConnAckPacket connAckPacket);
@@ -30,8 +34,12 @@ namespace MQTTnet.Formatter

        MqttSubscribePacket CreateSubscribePacket(MqttClientSubscribeOptions options);

+        MqttSubAckPacket CreateSubAckPacket(MqttSubscribePacket subscribePacket, Server.MqttClientSubscribeResult subscribeResult);
+
        MqttUnsubscribePacket CreateUnsubscribePacket(MqttClientUnsubscribeOptions options);

+        MqttUnsubAckPacket CreateUnsubAckPacket(MqttUnsubscribePacket unsubscribePacket, List<MqttUnsubscribeReasonCode> reasonCodes);
+
        MqttDisconnectPacket CreateDisconnectPacket(MqttClientDisconnectOptions options);

        MqttClientPublishResult CreatePublishResult(MqttPubAckPacket pubAckPacket);
@@ -1,6 +1,4 @@
-using System;
-
-namespace MQTTnet.Formatter
+namespace MQTTnet.Formatter
 {
    public interface IMqttPacketBodyReader
    {
@@ -6,13 +6,13 @@ using MQTTnet.Exceptions;

 namespace MQTTnet.Formatter
 {
-    public class MqttPacketBodyReader : IMqttPacketBodyReader
+    public sealed class MqttPacketBodyReader : IMqttPacketBodyReader
    {
-        private readonly byte[] _buffer;
-        private readonly int _initialOffset;
-        private readonly int _length;
+        readonly byte[] _buffer;
+        readonly int _initialOffset;
+        readonly int _length;

-        private int _offset;
+        int _offset;

        public MqttPacketBodyReader(byte[] buffer, int offset, int length)
        {
@@ -134,7 +134,7 @@ namespace MQTTnet.Formatter
        {
            if (_length < _offset + length)
            {
-                throw new ArgumentOutOfRangeException(nameof(_buffer), $"Expected at least {_offset + length} bytes but there are only {_length} bytes");
+                throw new MqttProtocolViolationException($"Expected at least {_offset + length} bytes but there are only {_length} bytes");
            }
        }

@@ -8,10 +8,10 @@ using MQTTnet.Packets;

 namespace MQTTnet.Formatter
 {
-    public class MqttPacketFormatterAdapter
+    public sealed class MqttPacketFormatterAdapter
    {
        IMqttPacketFormatter _formatter;
-               
+
        public MqttPacketFormatterAdapter(MqttProtocolVersion protocolVersion)
            : this(protocolVersion, new MqttPacketWriter())
        {
@@ -26,7 +26,7 @@ namespace MQTTnet.Formatter
        public MqttPacketFormatterAdapter(IMqttPacketWriter writer)
        {
            Writer = writer;
-        }        
+        }

        public MqttProtocolVersion ProtocolVersion { get; private set; } = MqttProtocolVersion.Unknown;

@@ -39,7 +39,7 @@ namespace MQTTnet.Formatter
                return _formatter.DataConverter;
            }
        }
-                
+
        public IMqttPacketWriter Writer { get; }

        public ArraySegment<byte> Encode(MqttBasePacket packet)
@@ -69,32 +69,21 @@ namespace MQTTnet.Formatter
        {
            var protocolVersion = ParseProtocolVersion(receivedMqttPacket);

-            // Reset the position of the stream because the protocol version is part of 
+            // Reset the position of the stream because the protocol version is part of
            // the regular CONNECT packet. So it will not properly deserialized if this
            // data is missing.
-            receivedMqttPacket.Body.Seek(0);
+            receivedMqttPacket.BodyReader.Seek(0);

            UseProtocolVersion(protocolVersion);
        }

-        private void UseProtocolVersion(MqttProtocolVersion protocolVersion)
-        {
-            if (protocolVersion == MqttProtocolVersion.Unknown)
-            {
-                throw new InvalidOperationException("MQTT protocol version is invalid.");
-            }
-
-            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:
@@ -116,12 +105,31 @@ namespace MQTTnet.Formatter
            }
        }

-        MqttProtocolVersion ParseProtocolVersion(ReceivedMqttPacket receivedMqttPacket)
+        void UseProtocolVersion(MqttProtocolVersion protocolVersion)
+        {
+            if (protocolVersion == MqttProtocolVersion.Unknown)
+            {
+                throw new InvalidOperationException("MQTT protocol version is invalid.");
+            }
+
+            ProtocolVersion = protocolVersion;
+            _formatter = GetMqttPacketFormatter(protocolVersion, Writer);
+        }
+
+        static MqttProtocolVersion ParseProtocolVersion(ReceivedMqttPacket receivedMqttPacket)
        {
            if (receivedMqttPacket == null) throw new ArgumentNullException(nameof(receivedMqttPacket));

-            var protocolName = receivedMqttPacket.Body.ReadStringWithLengthPrefix();
-            var protocolLevel = receivedMqttPacket.Body.ReadByte();
+            if (receivedMqttPacket.BodyReader.Length < 7)
+            {
+                // 2 byte protocol name length
+                // at least 4 byte protocol name
+                // 1 byte protocol level
+                throw new MqttProtocolViolationException("CONNECT packet must have at least 7 bytes.");
+            }
+
+            var protocolName = receivedMqttPacket.BodyReader.ReadStringWithLengthPrefix();
+            var protocolLevel = receivedMqttPacket.BodyReader.ReadByte();

            if (protocolName == "MQTT")
            {
@@ -1,114 +0,0 @@
-using System;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Channel;
-using MQTTnet.Exceptions;
-
-namespace MQTTnet.Formatter
-{
-    public class MqttPacketReader
-    {
-        private readonly byte[] _singleByteBuffer = new byte[1];
-
-        private readonly IMqttChannel _channel;
-
-        public MqttPacketReader(IMqttChannel channel)
-        {
-            _channel = channel ?? throw new ArgumentNullException(nameof(channel));
-        }
-
-        public async Task<ReadFixedHeaderResult> ReadFixedHeaderAsync(byte[] fixedHeaderBuffer, CancellationToken cancellationToken)
-        {
-            // The MQTT fixed header contains 1 byte of flags and at least 1 byte for the remaining data length.
-            // So in all cases at least 2 bytes must be read for a complete MQTT packet.
-            var buffer = fixedHeaderBuffer;
-            var totalBytesRead = 0;
-
-            while (totalBytesRead < buffer.Length)
-            {
-                var bytesRead = await _channel.ReadAsync(buffer, totalBytesRead, buffer.Length - totalBytesRead, cancellationToken).ConfigureAwait(false);
-
-                if (cancellationToken.IsCancellationRequested)
-                {
-                    return null;
-                }
-                
-                if (bytesRead == 0)
-                {
-                    return new ReadFixedHeaderResult
-                    {
-                        ConnectionClosed = true
-                    };
-                }
-                
-                totalBytesRead += bytesRead;
-            }
-
-            var hasRemainingLength = buffer[1] != 0;
-            if (!hasRemainingLength)
-            {
-                return new ReadFixedHeaderResult
-                {
-                    FixedHeader = new MqttFixedHeader(buffer[0], 0, totalBytesRead)
-                };
-            }
-
-            var bodyLength = await ReadBodyLengthAsync(buffer[1], cancellationToken).ConfigureAwait(false);
-
-            if (!bodyLength.HasValue)
-            {
-                return new ReadFixedHeaderResult
-                {
-                    ConnectionClosed = true
-                };
-            }
-
-            totalBytesRead += bodyLength.Value;
-            return new ReadFixedHeaderResult
-            {
-                FixedHeader = new MqttFixedHeader(buffer[0], bodyLength.Value, totalBytesRead)
-            };
-        }
-
-        private async Task<int?> ReadBodyLengthAsync(byte initialEncodedByte, CancellationToken cancellationToken)
-        {
-            var offset = 0;
-            var multiplier = 128;
-            var value = initialEncodedByte & 127;
-            int encodedByte = initialEncodedByte;
-
-            while ((encodedByte & 128) != 0)
-            {
-                offset++;
-                if (offset > 3)
-                {
-                    throw new MqttProtocolViolationException("Remaining length is invalid.");
-                }
-
-                if (cancellationToken.IsCancellationRequested)
-                {
-                    return null;
-                }
-
-                var readCount = await _channel.ReadAsync(_singleByteBuffer, 0, 1, cancellationToken).ConfigureAwait(false);
-
-                if (cancellationToken.IsCancellationRequested)
-                {
-                    return null;
-                }
-
-                if (readCount == 0)
-                {
-                    return null;
-                }
-
-                encodedByte = _singleByteBuffer[0];
-
-                value += (encodedByte & 127) * multiplier;
-                multiplier *= 128;
-            }
-
-            return value;
-        }
-    }
-}
@@ -13,11 +13,9 @@ namespace MQTTnet.Formatter
    /// </summary>
    public sealed class MqttPacketWriter : IMqttPacketWriter
    {
-        static readonly ArraySegment<byte> ZeroVariableLengthIntegerArray = new ArraySegment<byte>(new byte[1], 0, 1);
-        static readonly ArraySegment<byte> ZeroTwoByteIntegerArray = new ArraySegment<byte>(new byte[2], 0, 2);
+        public static int InitialBufferSize = 4096;

-        public static int InitialBufferSize = 128;
-        public static int MaxBufferSize = 4096;
+        public static int MaxBufferSize = 4096 * 4;

        byte[] _buffer = new byte[InitialBufferSize];

@@ -38,59 +36,72 @@ namespace MQTTnet.Formatter
            var x = value;
            do
            {
-                x = x / 128;
+                x /= 128;
                result++;
            } while (x > 0);

            return result;
        }

-        public static ArraySegment<byte> EncodeVariableLengthInteger(uint value)
+        public void WriteVariableLengthInteger(uint value)
        {
            if (value == 0)
            {
-                return ZeroVariableLengthIntegerArray;
+                _buffer[_offset] = 0;
+                IncreasePosition(1);
+
+                return;
            }

            if (value <= 127)
            {
-                return new ArraySegment<byte>(new[] { (byte)value }, 0, 1);
+                _buffer[_offset] = (byte)value;
+                IncreasePosition(1);
+
+                return;
            }

-            var buffer = new byte[4];
-            var bufferOffset = 0;
-
+            var size = 0;
            var x = value;
            do
            {
                var encodedByte = x % 128;
-                x = x / 128;
+                x /= 128;
                if (x > 0)
                {
-                    encodedByte = encodedByte | 128;
+                    encodedByte |= 128;
                }

-                buffer[bufferOffset] = (byte)encodedByte;
-                bufferOffset++;
+                _buffer[_offset + size] = (byte)encodedByte;
+                size++;
            } while (x > 0);

-            return new ArraySegment<byte>(buffer, 0, bufferOffset);
-        }
-
-        public void WriteVariableLengthInteger(uint value)
-        {
-            Write(EncodeVariableLengthInteger(value));
+            IncreasePosition(size);
        }

        public void WriteWithLengthPrefix(string value)
        {
            if (string.IsNullOrEmpty(value))
            {
-                Write(ZeroTwoByteIntegerArray);
+                EnsureAdditionalCapacity(2);
+
+                _buffer[_offset] = 0;
+                _buffer[_offset + 1] = 0;
+
+                IncreasePosition(2);
            }
            else
            {
-                WriteWithLengthPrefix(Encoding.UTF8.GetBytes(value));
+                var bufferSize = Encoding.UTF8.GetByteCount(value);
+
+                EnsureAdditionalCapacity(bufferSize + 2);
+
+                _buffer[_offset] = (byte)(bufferSize >> 8);
+                _buffer[_offset + 1] = (byte)bufferSize;
+
+                Encoding.UTF8.GetBytes(value, 0, value.Length, _buffer, _offset + 2);
+
+                IncreasePosition(bufferSize + 2);
            }
        }

@@ -98,13 +109,22 @@ namespace MQTTnet.Formatter
        {
            if (value == null || value.Length == 0)
            {
-                Write(ZeroTwoByteIntegerArray);
+                EnsureAdditionalCapacity(2);
+
+                _buffer[_offset] = 0;
+                _buffer[_offset + 1] = 0;
+
+                IncreasePosition(2);
            }
            else
            {
                EnsureAdditionalCapacity(value.Length + 2);
-                Write((ushort)value.Length);
-                Write(value, 0, value.Length);
+
+                _buffer[_offset] = (byte)(value.Length >> 8);
+                _buffer[_offset + 1] = (byte)value.Length;
+
+                Array.Copy(value, 0, _buffer, _offset + 2, value.Length);
+                IncreasePosition(value.Length + 2);
            }
        }

@@ -143,8 +163,6 @@ namespace MQTTnet.Formatter

        public void Write(IMqttPacketWriter propertyWriter)
        {
-            if (propertyWriter == null) throw new ArgumentNullException(nameof(propertyWriter));
-
            if (propertyWriter is MqttPacketWriter writer)
            {
                if (writer.Length == 0)
@@ -156,7 +174,12 @@ namespace MQTTnet.Formatter
                return;
            }

-            throw new InvalidOperationException($"{nameof(propertyWriter)} must be of type {typeof(MqttPacketWriter).Name}");
+            if (propertyWriter == null)
+            {
+                throw new ArgumentNullException(nameof(propertyWriter));
+            }
+
+            throw new InvalidOperationException($"{nameof(propertyWriter)} must be of type {nameof(MqttPacketWriter)}");
        }

        public void Reset(int length)
@@ -179,8 +202,8 @@ namespace MQTTnet.Formatter
        {
            // This method frees the used memory by shrinking the buffer. This is required because the buffer
            // is used across several messages. In general this is not a big issue because subsequent Ping packages
-            // have the same size but a very big publish package with 100 MB of payload will increase the buffer 
-            // a lot and the size will never reduced. So this method tries to find a size which can be held in 
+            // have the same size but a very big publish package with 100 MB of payload will increase the buffer
+            // a lot and the size will never reduced. So this method tries to find a size which can be held in
            // memory for a long time without causing troubles.

            if (_buffer.Length < MaxBufferSize)
@@ -191,11 +214,6 @@ namespace MQTTnet.Formatter
            Array.Resize(ref _buffer, MaxBufferSize);
        }

-        void Write(ArraySegment<byte> buffer)
-        {
-            Write(buffer.Array, buffer.Offset, buffer.Count);
-        }
-
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void EnsureAdditionalCapacity(int additionalCapacity)
        {
@@ -9,6 +9,7 @@ using MQTTnet.Packets;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using MqttClientSubscribeResult = MQTTnet.Client.Subscribing.MqttClientSubscribeResult;

@@ -39,6 +40,15 @@ namespace MQTTnet.Formatter.V3
            };
        }

+        public MqttBasePacket CreatePubRecPacket(MqttPublishPacket publishPacket)
+        {
+            return new MqttPubRecPacket
+            {
+                PacketIdentifier = publishPacket.PacketIdentifier,
+                ReasonCode = MqttPubRecReasonCode.Success
+            };
+        }
+
        public MqttApplicationMessage CreateApplicationMessage(MqttPublishPacket publishPacket)
        {
            if (publishPacket == null) throw new ArgumentNullException(nameof(publishPacket));
@@ -172,6 +182,18 @@ namespace MQTTnet.Formatter.V3
            return subscribePacket;
        }

+        public MqttSubAckPacket CreateSubAckPacket(MqttSubscribePacket subscribePacket, Server.MqttClientSubscribeResult subscribeResult)
+        {
+            var subackPacket = new MqttSubAckPacket
+            {
+                PacketIdentifier = subscribePacket.PacketIdentifier
+            };
+
+            subackPacket.ReturnCodes.AddRange(subscribeResult.ReturnCodes);
+
+            return subackPacket;
+        }
+
        public MqttUnsubscribePacket CreateUnsubscribePacket(MqttClientUnsubscribeOptions options)
        {
            if (options == null) throw new ArgumentNullException(nameof(options));
@@ -182,6 +204,15 @@ namespace MQTTnet.Formatter.V3
            return unsubscribePacket;
        }

+        public MqttUnsubAckPacket CreateUnsubAckPacket(MqttUnsubscribePacket unsubscribePacket, List<MqttUnsubscribeReasonCode> reasonCodes)
+        {
+            return new MqttUnsubAckPacket
+            {
+                PacketIdentifier = unsubscribePacket.PacketIdentifier,
+                ReasonCodes = reasonCodes
+            };
+        }
+
        public MqttDisconnectPacket CreateDisconnectPacket(MqttClientDisconnectOptions options)
        {
            if (options.ReasonCode != MqttClientDisconnectReason.NormalDisconnection || options.ReasonString != null)
--- a/Show More
+++ b/Show More