Improve RPC client handling.

Update codeql-analysis.yml
Merge remote-tracking branch 'origin/master'
2026-10-15 00:15:15 +08:00 · 2021-02-26 10:55:26 +01:00 · 2021-02-23 12:05:24 +01:00 · 2021-02-23 11:46:38 +01:00 · 2021-02-23 11:46:16 +01:00 · 2021-02-23 11:45:22 +01:00
243 changed files with 4492 additions and 3923 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
@@ -0,0 +1,67 @@
+# For most projects, this workflow file will not need changing; you simply need
+# to commit it to your repository.
+#
+# You may wish to alter this file to override the set of languages analyzed,
+# or to provide custom queries or build logic.
+#
+# ******** NOTE ********
+# We have attempted to detect the languages in your repository. Please check
+# the `language` matrix defined below to confirm you have the correct set of
+# supported CodeQL languages.
+#
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [ master ]
+  schedule:
+    - cron: '23 9 * * 6'
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'csharp' ]
+        # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python' ]
+        # Learn more:
+        # https://docs.github.com/en/free-pro-team@latest/github/finding-security-vulnerabilities-and-errors-in-your-code/configuring-code-scanning#changing-the-languages-that-are-analyzed
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v1
+      with:
+        languages: ${{ matrix.language }}
+        # If you wish to specify custom queries, you can do so here or in a config file.
+        # By default, queries listed here will override any specified in a config file.
+        # Prefix the list here with "+" to use these queries and those in the config file.
+        # queries: ./path/to/local/query, your-org/your-repo/queries@main
+
+    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
+    # If this step fails, then you should remove it and run the build manually (see below)
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v1
+
+    # ℹ️ Command-line programs to run using the OS shell.
+    # 📚 https://git.io/JvXDl
+
+    # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
+    #    and modify them (or add more) to build your code if your project
+    #    uses a compiled language
+
+    #- run: |
+    #   make bootstrap
+    #   make release
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v1
@@ -19,10 +19,14 @@
        <dependency id="MQTTnet" version="$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.AspNetCore.*" 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 Blazor</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 +26,26 @@
    <!-- Images -->
    <file src="..\Images\Logo_128x128.png" target="images\" />

+    <!-- .NET 5.0 -->
+    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\net5.0\MQTTnet.Extensions.ManagedClient.*" 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\" />
+
+    <!-- .NET Standard 2.1 -->
+    <file src="..\Source\MQTTnet.Extensions.ManagedClient\bin\Release\netstandard2.1\MQTTnet.Extensions.ManagedClient.*" target="lib\netstandard2.1\" />

    <!-- 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.ManagedClient.*" 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 Blazor</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 +26,26 @@
    <!-- Images -->
    <file src="..\Images\Logo_128x128.png" target="images\" />

+    <!-- .NET 5.0 -->
+    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\net5.0\MQTTnet.Extensions.Rpc.*" 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\" />
+
+    <!-- .NET Standard 2.1 -->
+    <file src="..\Source\MQTTnet.Extensions.Rpc\bin\Release\netstandard2.1\MQTTnet.Extensions.Rpc.*" target="lib\netstandard2.1\" />

    <!-- 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>
@@ -13,24 +13,10 @@
    <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 Blazor</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="$nugetVersion" />
-        <dependency id="WebSocket4Net" version="0.15.2" />
-      </group>
-      <group targetFramework="netstandard2.0">
-        <dependency id="MQTTnet" version="$nugetVersion" />
-        <dependency id="WebSocket4Net" version="0.15.2" />
-      </group>
-      <group targetFramework="netstandard2.1">
-        <dependency id="MQTTnet" version="$nugetVersion" />
-        <dependency id="WebSocket4Net" version="0.15.2" />
-      </group>
-      <group targetFramework="uap10.0">
-        <dependency id="MQTTnet" version="$nugetVersion" />
-        <dependency id="WebSocket4Net" version="0.15.2" />
-      </group>
+      <dependency id="MQTTnet" version="$nugetVersion" />
+      <dependency id="WebSocket4Net" version="0.15.2" />
    </dependencies>
  </metadata>

@@ -41,20 +27,26 @@
    <!-- Images -->
    <file src="..\Images\Logo_128x128.png" target="images\" />

+    <!-- .NET 5.0 -->
+    <file src="..\Source\MQTTnet.Extensions.WebSocket4Net\bin\Release\net5.0\MQTTnet.Extensions.WebSocket4Net.*" 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\" />
+
+    <!-- .NET Standard 2.1 -->
+    <file src="..\Source\MQTTnet.Extensions.WebSocket4Net\bin\Release\netstandard2.1\MQTTnet.Extensions.WebSocket4Net.*" target="lib\netstandard2.1\" />

    <!-- 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>
@@ -12,41 +12,31 @@
    <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>
-* [Client] Fixed wrong value for "ClientWasConnected" in "MqttClientDisconnectedEventArgs" #976 (thanks to @dbeinder).
-* [Client] Added direct support for Amazon AWS connections (requires .NET Core 3.1) (thanks to @henning-krause).
-* [Client] handle disconnect package and propagate disconnect reason code (thanks to @JanEggers)
-* [ManagedClient] Exposed the internal MQTT client.
-* [Server] Added client message queue interceptor for QoS level (thanks to @msallin).
-* [Server] improved behavior when multiple connections fight over a session (thanks to @JanEggers)
-* [Server] Exposed _ClientDisconnectedInterceptor_ (thanks to @SeppPenner).
+* [Core] Fixed some issues in nuget packages.
+* [Client] Changed exception types so that proper exceptions are thrown when connecting (#1082).
+* [Client] Exposed Dup flag in application messages.
+* [Client] Improved keep alive message sending.
+* [RpcClient] Fixed an issue when using a custom application message reveived handler (#1093).
+* [RpcClient] Fixed a race condition when using timeout and cancellation token at the same time (BREAKING CHANGE!).
+* [Server] Improved keep alive message sending.
+
+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 Blazor</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="net452" />
+      <group targetFramework="net461" />
      <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" />      
-      </group>
-      <group targetFramework="netstandard2.0">
-        <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="netstandard2.1">
-        <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="netcoreapp3.1">
-        <dependency id="NETStandard.Library" version="2.0.0" />
+        <dependency id="NETStandard.Library" version="1.6.1" />
        <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="netstandard2.0" />
+      <group targetFramework="netstandard2.1" />
+      <group targetFramework="netcoreapp3.1" />
+      <group targetFramework="net5.0" />
      <group targetFramework="uap10.0">
        <dependency id="Microsoft.NETCore.UniversalWindowsPlatform" version="6.2.10" />
      </group>
@@ -60,26 +50,29 @@
    <!-- 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\"/>
+    <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>
@@ -31,10 +31,12 @@ vstest.console.exe ..\Tests\MQTTnet.AspNetCore.Tests\bin\Release\netcoreapp3.1\M
 &$msbuild ..\Source\MQTTnet\MQTTnet.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.1" /p:FileVersion=$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=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
+&$msbuild ..\Source\MQTTnet\MQTTnet.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net5.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"

 # Build the ASP.NET Core 2.0 extension
 &$msbuild ..\Source\MQTTnet.AspNetCore\MQTTnet.AspNetCore.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet.AspNetCore\MQTTnet.AspNetCore.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"
+&$msbuild ..\Source\MQTTnet.AspNetCore\MQTTnet.AspNetCore.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net5.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"

 # Build the RPC extension
 &$msbuild ..\Source\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net452" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
@@ -43,6 +45,7 @@ vstest.console.exe ..\Tests\MQTTnet.AspNetCore.Tests\bin\Release\netcoreapp3.1\M
 &$msbuild ..\Source\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.1" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.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"
+&$msbuild ..\Source\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net5.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"

 # Build the Managed Client extension
 &$msbuild ..\Source\MQTTnet.Extensions.ManagedClient\MQTTnet.Extensions.ManagedClient.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net452" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
@@ -51,6 +54,7 @@ vstest.console.exe ..\Tests\MQTTnet.AspNetCore.Tests\bin\Release\netcoreapp3.1\M
 &$msbuild ..\Source\MQTTnet.Extensions.ManagedClient\MQTTnet.Extensions.ManagedClient.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet.Extensions.ManagedClient\MQTTnet.Extensions.ManagedClient.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.1" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet.Extensions.ManagedClient\MQTTnet.Extensions.ManagedClient.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="uap10.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
+&$msbuild ..\Source\MQTTnet.Extensions.ManagedClient\MQTTnet.Extensions.ManagedClient.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net5.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"

 # Build the WebSocket4Net extension
 &$msbuild ..\Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net452" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
@@ -59,11 +63,16 @@ vstest.console.exe ..\Tests\MQTTnet.AspNetCore.Tests\bin\Release\netcoreapp3.1\M
 &$msbuild ..\Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.1" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
 &$msbuild ..\Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="uap10.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
+&$msbuild ..\Source\MQTTnet.Extensions.WebSocket4Net\MQTTnet.Extensions.WebSocket4Net.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net5.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"

 # Create NuGet packages.

 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
@@ -80,6 +89,7 @@ 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
@@ -90,9 +100,9 @@ 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

-$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\publish"
+$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\net5.0\publish"
 $destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Portable-v$nugetVersion.zip"
 If(Test-path $destination) {Remove-item $destination}
 Add-Type -assembly "system.io.compression.filesystem"
@@ -101,9 +111,9 @@ 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

-$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\linux-x64\publish"
+$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\net5.0\linux-x64\publish"
 $destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Linux-x64-v$nugetVersion.zip"
 If(Test-path $destination) {Remove-item $destination}
 Add-Type -assembly "system.io.compression.filesystem"
@@ -112,9 +122,9 @@ 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

-$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\linux-ARM\publish"
+$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\net5.0\linux-ARM\publish"
 $destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Linux-ARM-v$nugetVersion.zip"
 If(Test-path $destination) {Remove-item $destination}
 Add-Type -assembly "system.io.compression.filesystem"
@@ -123,9 +133,9 @@ 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

-$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\netcoreapp3.1\win-x64\publish"
+$source = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\Release\net5.0\win-x64\publish"
 $destination = (Convert-Path .) + "\..\Source\MQTTnet.Server\bin\MQTTnet.Server-Windows-x64-v$nugetVersion.zip"
 If(Test-path $destination) {Remove-item $destination}
 Add-Type -assembly "system.io.compression.filesystem"
@@ -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}"
@@ -57,11 +55,11 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Apps", "Apps", "{A56E3128-1
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Blazor", "Blazor", "{61B165A0-5AA8-4E04-A53D-A22A84AA6EB7}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MQTTnet.Test.BlazorApp.Server", "Tests\MQTTnet.Test.BlazorApp\Server\MQTTnet.Test.BlazorApp.Server.csproj", "{A9662AF3-3520-4BF8-9DFF-C55C0C33D08F}"
+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("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MQTTnet.Test.BlazorApp.Client", "Tests\MQTTnet.Test.BlazorApp\Client\MQTTnet.Test.BlazorApp.Client.csproj", "{D260D63D-7902-4C55-9665-84C5CACBBB24}"
+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("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MQTTnet.Test.BlazorApp.Shared", "Tests\MQTTnet.Test.BlazorApp\Shared\MQTTnet.Test.BlazorApp.Shared.csproj", "{DDB069BA-6E1A-48C7-B374-5D903B553CAD}"
+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
@@ -91,29 +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
@@ -328,7 +303,6 @@ Global
 	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}
@@ -11,4 +11,6 @@
 	<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/=PINGREQ/@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)*
@@ -64,15 +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
+* 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

@@ -97,11 +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.

@@ -111,7 +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();
        }
@@ -12,6 +12,7 @@ namespace MQTTnet.AspNetCore.Extensions
 #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 =>
@@ -19,5 +20,6 @@ namespace MQTTnet.AspNetCore.Extensions
                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;
@@ -1,7 +1,7 @@
 <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 />
@@ -21,11 +21,11 @@
    <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="'$(TargetFramework)' != 'netcoreapp3.1'">
+  <ItemGroup Condition="'$(TargetFramework)' != 'netcoreapp3.1' and '$(TargetFramework)' != 'net5.0' ">
    <PackageReference Include="Microsoft.AspNetCore.Http.Connections" Version="1.1.0" />
  </ItemGroup>

@@ -66,10 +66,10 @@ namespace MQTTnet.AspNetCore
        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; }

        IHttpContextFeature Http => Connection.Features.Get<IHttpContextFeature>();

@@ -92,7 +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;

@@ -128,7 +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)
@@ -147,14 +147,14 @@ namespace MQTTnet.AspNetCore
            }
            catch (Exception e)
            {
-                // completing the cannels makes sure that there is no more data read after a protocol error
+                // 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();
@@ -167,7 +167,7 @@ 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;
            using (await _writerLock.WaitAsync(cancellationToken).ConfigureAwait(false))
@@ -180,6 +180,7 @@ namespace MQTTnet.AspNetCore
                {
                    BytesSent += msg.Length;
                }
+
                PacketFormatterAdapter.FreeBuffer();
            }
        }
@@ -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);
                    }
@@ -8,8 +8,6 @@ namespace MQTTnet.Extensions.ManagedClient
    {
        IMqttClientOptions ClientOptions { get; }

-        bool AutoReconnect { get; }
-
        TimeSpan AutoReconnectDelay { get; }

        TimeSpan ConnectionCheckInterval { get; }
@@ -1,7 +1,7 @@
 <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 />
@@ -32,7 +32,6 @@ namespace MQTTnet.Extensions.ManagedClient
        readonly HashSet<string> _unsubscriptions = new HashSet<string>();
        readonly SemaphoreSlim _subscriptionsQueuedSignal = new SemaphoreSlim(0);

-        readonly IMqttClient _mqttClient;
        readonly IMqttNetScopedLogger _logger;

        readonly AsyncLock _messageQueueLock = new AsyncLock();
@@ -45,39 +44,38 @@ namespace MQTTnet.Extensions.ManagedClient

        public ManagedMqttClient(IMqttClient mqttClient, IMqttNetLogger logger)
        {
-            _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
-            InternalClient = 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; }
@@ -94,14 +92,14 @@ 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)
@@ -110,16 +108,13 @@ namespace MQTTnet.Extensions.ManagedClient
                }
            }

-            if (Options.AutoReconnect)
-            {
-                var cancellationTokenSource = new CancellationTokenSource();
-                var cancellationToken = cancellationTokenSource.Token;
-                _connectionCancellationToken = cancellationTokenSource;
+            var cancellationTokenSource = new CancellationTokenSource();
+            var cancellationToken = cancellationTokenSource.Token;
+            _connectionCancellationToken = cancellationTokenSource;
+
+            _maintainConnectionTask = Task.Run(() => MaintainConnectionAsync(cancellationToken), cancellationToken);
+            _maintainConnectionTask.RunInBackground(_logger);

-                _maintainConnectionTask = Task.Run(() => MaintainConnectionAsync(cancellationToken), cancellationToken);
-                _maintainConnectionTask.Forget(_logger);
-            }
-            
            _logger.Info("Started");
        }

@@ -141,7 +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)
@@ -228,6 +223,7 @@ namespace MQTTnet.Extensions.ManagedClient
                    _unsubscriptions.Remove(topicFilter.Topic);
                }
            }
+
            _subscriptionsQueuedSignal.Release();

            return Task.FromResult(0);
@@ -267,7 +263,7 @@ namespace MQTTnet.Extensions.ManagedClient

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

@@ -296,7 +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)
                    {
@@ -305,7 +308,9 @@ namespace MQTTnet.Extensions.ManagedClient

                    _logger.Info("Stopped");
                }
+
                _reconnectSubscriptions.Clear();
+
                lock (_subscriptions)
                {
                    _subscriptions.Clear();
@@ -318,7 +323,7 @@ namespace MQTTnet.Extensions.ManagedClient
        {
            try
            {
-                var connectionState = await ReconnectIfRequiredAsync().ConfigureAwait(false);
+                var connectionState = await ReconnectIfRequiredAsync(cancellationToken).ConfigureAwait(false);
                if (connectionState == ReconnectionResult.NotConnected)
                {
                    StopPublishing();
@@ -361,7 +366,7 @@ namespace MQTTnet.Extensions.ManagedClient
        {
            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.
@@ -400,7 +405,7 @@ namespace MQTTnet.Extensions.ManagedClient
            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
                {
@@ -422,7 +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)
                {
@@ -447,7 +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
            {
@@ -463,6 +468,7 @@ namespace MQTTnet.Extensions.ManagedClient
        async Task PublishSubscriptionsAsync(TimeSpan timeout, CancellationToken cancellationToken)
        {
            var endTime = DateTime.UtcNow + timeout;
+
            while (await _subscriptionsQueuedSignal.WaitAsync(GetRemainingTime(endTime), cancellationToken).ConfigureAwait(false))
            {
                List<MqttTopicFilter> subscriptions;
@@ -481,7 +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)
                {
@@ -497,12 +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)
@@ -521,7 +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)
@@ -541,16 +547,16 @@ namespace MQTTnet.Extensions.ManagedClient
            }
        }

-        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)
@@ -576,7 +582,7 @@ namespace MQTTnet.Extensions.ManagedClient
            var cancellationToken = cancellationTokenSource.Token;
            _publishingCancellationToken = cancellationTokenSource;

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

        void StopPublishing()
@@ -8,8 +8,6 @@ namespace MQTTnet.Extensions.ManagedClient
    {
        public IMqttClientOptions ClientOptions { get; set; }

-        public bool AutoReconnect { get; set; } = true;
-
        public TimeSpan AutoReconnectDelay { get; set; } = TimeSpan.FromSeconds(5);

        public TimeSpan ConnectionCheckInterval { get; set; } = TimeSpan.FromSeconds(1);
@@ -68,18 +68,6 @@ namespace MQTTnet.Extensions.ManagedClient
            options(_clientOptionsBuilder);
            return this;
        }
-
-        public ManagedMqttClientOptionsBuilder WithAutoReconnect()
-        {
-            _options.AutoReconnect = true;
-            return this;
-        }
-
-        public ManagedMqttClientOptionsBuilder WithoutAutoReconnect()
-        {
-            _options.AutoReconnect = false;
-            return this;
-        }
        
        public ManagedMqttClientOptions Build()
        {
@@ -0,0 +1,14 @@
+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, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel);
+
+        Task<byte[]> ExecuteAsync(string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, CancellationToken cancellationToken);
+    }
+}
@@ -1,7 +1,7 @@
 <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 />
@@ -5,18 +5,19 @@ using MQTTnet.Extensions.Rpc.Options.TopicGeneration;
 using MQTTnet.Protocol;
 using System;
 using System.Collections.Concurrent;
-using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Client.Subscribing;
+using MQTTnet.Implementations;

 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())
@@ -35,30 +36,30 @@ namespace MQTTnet.Extensions.Rpc
            _mqttClient.ApplicationMessageReceivedHandler = _applicationMessageReceivedHandler;
        }

-        public Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
+        public async Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
        {
-            return ExecuteAsync(timeout, methodName, Encoding.UTF8.GetBytes(payload), qualityOfServiceLevel, CancellationToken.None);
+            using (var timeoutToken = new CancellationTokenSource(timeout))
+            {
+                try
+                {
+                    return await ExecuteAsync(methodName, payload, qualityOfServiceLevel, timeoutToken.Token).ConfigureAwait(false);
+                }
+                catch (OperationCanceledException exception)
+                {
+                    if (timeoutToken.IsCancellationRequested)
+                    {
+                        throw new MqttCommunicationTimedOutException(exception);
+                    }
+
+                    throw;
+                }
+            }
        }

-        public Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel, CancellationToken cancellationToken)
-        {
-            return ExecuteAsync(timeout, methodName, Encoding.UTF8.GetBytes(payload), qualityOfServiceLevel, cancellationToken);
-        }
-
-        public Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
-        {
-            return ExecuteAsync(timeout, methodName, payload, qualityOfServiceLevel, CancellationToken.None);
-        }
-
-        public async Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, CancellationToken cancellationToken)
+        public async Task<byte[]> ExecuteAsync(string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, CancellationToken cancellationToken)
        {
            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.");
@@ -93,62 +94,54 @@ namespace MQTTnet.Extensions.Rpc

            try
            {
-                var tcs = new TaskCompletionSource<byte[]>();
-                if (!_waitingCalls.TryAdd(responseTopic, tcs))
+#if NET452
+                var promise = new TaskCompletionSource<byte[]>();
+#else
+                var promise = new TaskCompletionSource<byte[]>(TaskCreationOptions.RunContinuationsAsynchronously);
+#endif
+                
+                if (!_waitingCalls.TryAdd(responseTopic, promise))
                {
                    throw new InvalidOperationException();
                }

-                await _mqttClient.SubscribeAsync(responseTopic, qualityOfServiceLevel).ConfigureAwait(false);
-                await _mqttClient.PublishAsync(requestMessage).ConfigureAwait(false);
+                var subscribeOptions = new MqttClientSubscribeOptionsBuilder()
+                    .WithTopicFilter(responseTopic, qualityOfServiceLevel)
+                    .Build();

-                using (var timeoutCts = new CancellationTokenSource(timeout))
-                using (var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, timeoutCts.Token))
+                await _mqttClient.SubscribeAsync(subscribeOptions, cancellationToken).ConfigureAwait(false);
+                await _mqttClient.PublishAsync(requestMessage, cancellationToken).ConfigureAwait(false);
+
+                using (cancellationToken.Register(() => { promise.TrySetCanceled(); }))
                {
-                    linkedCts.Token.Register(() =>
-                    {
-                        if (!tcs.Task.IsCompleted && !tcs.Task.IsFaulted && !tcs.Task.IsCanceled)
-                        {
-                            tcs.TrySetCanceled();
-                        }
-                    });
-
-                    try
-                    {
-                        var result = await tcs.Task.ConfigureAwait(false);
-                        timeoutCts.Cancel(false);
-                        return result;
-                    }
-                    catch (OperationCanceledException exception)
-                    {
-                        if (timeoutCts.IsCancellationRequested && !cancellationToken.IsCancellationRequested)
-                        {
-                            throw new MqttCommunicationTimedOutException(exception);
-                        }
-                        else
-                        {
-                            throw;
-                        }
-                    }
+                    return await promise.Task.ConfigureAwait(false);
                }
            }
            finally
            {
                _waitingCalls.TryRemove(responseTopic, out _);
+
                await _mqttClient.UnsubscribeAsync(responseTopic).ConfigureAwait(false);
            }
        }

-        private Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
+        Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
        {
-            if (!_waitingCalls.TryRemove(eventArgs.ApplicationMessage.Topic, out var tcs))
+            if (!_waitingCalls.TryRemove(eventArgs.ApplicationMessage.Topic, out var promise))
            {
-                return Task.FromResult(0);
+                return PlatformAbstractionLayer.CompletedTask;
            }

-            tcs.TrySetResult(eventArgs.ApplicationMessage.Payload);
+#if NET452
+            Task.Run(() => promise.TrySetResult(eventArgs.ApplicationMessage.Payload));
+#else
+            promise.TrySetResult(eventArgs.ApplicationMessage.Payload);
+#endif

-            return Task.FromResult(0);
+            // Set this message to handled to that other code can avoid execution etc.
+            eventArgs.IsHandled = true;
+
+            return PlatformAbstractionLayer.CompletedTask;
        }

        public void Dispose()
@@ -163,4 +156,4 @@ namespace MQTTnet.Extensions.Rpc
            _waitingCalls.Clear();
        }
    }
-}
+}
@@ -0,0 +1,19 @@
+using System;
+using System.Text;
+using System.Threading.Tasks;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Extensions.Rpc
+{
+    public static class MqttRpcClientExtensions
+    {
+        public static Task<byte[]> ExecuteAsync(this IMqttRpcClient client, TimeSpan timeout, string methodName, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
+        {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+
+            var buffer = Encoding.UTF8.GetBytes(payload ?? string.Empty);
+
+            return client.ExecuteAsync(timeout, methodName, buffer, qualityOfServiceLevel);
+        }
+    }
+}
@@ -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; }

@@ -2,10 +2,15 @@

 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,
@@ -20,12 +20,13 @@ namespace MQTTnet.Extensions.Rpc

        public async Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
        {
+            // First try to check if there is a pending RPC call! 
+            await _handleReceivedApplicationMessageAsync(eventArgs).ConfigureAwait(false);
+            
            if (OriginalHandler != null)
            {
                await OriginalHandler.HandleApplicationMessageReceivedAsync(eventArgs).ConfigureAwait(false);
            }
-
-            await _handleReceivedApplicationMessageAsync(eventArgs).ConfigureAwait(false);
        }
    }
 }
@@ -1,7 +1,7 @@
 <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 />
@@ -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);
-                }
-            }
-        }
-    }
-}
@@ -1,7 +1,7 @@
 <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>
@@ -39,12 +39,19 @@
  </ItemGroup>

  <ItemGroup>
-    <PackageReference Include="IronPython" Version="2.7.10" />
-    <PackageReference Include="IronPython.StdLib" Version="2.7.10" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.1.5" />
+    <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="5.5.1" />
-    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="5.5.1" />
+    <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>
@@ -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))
                {
@@ -116,10 +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);
@@ -181,8 +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)
@@ -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();
    }
@@ -11,6 +11,7 @@ using System.Runtime.InteropServices;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Diagnostics.PacketInspection;

 namespace MQTTnet.Adapter
 {
@@ -19,26 +20,26 @@ namespace MQTTnet.Adapter
        const uint ErrorOperationAborted = 0x800703E3;
        const int ReadBufferSize = 4096;

+        readonly byte[] _singleByteBuffer = new byte[1];
+        readonly byte[] _fixedHeaderBuffer = new byte[2];
+
+        readonly MqttPacketInspectorHandler _packetInspectorHandler;
        readonly IMqttNetScopedLogger _logger;
        readonly IMqttChannel _channel;
-        readonly MqttPacketReader _packetReader;
-
-        readonly byte[] _fixedHeaderBuffer = new byte[2];

        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));
        }

@@ -51,10 +52,10 @@ 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)
        {
@@ -79,7 +80,7 @@ namespace MQTTnet.Adapter
                    throw;
                }

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

@@ -107,97 +108,78 @@ 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)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            ThrowIfDisposed();
+
+            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);
+                }
+                catch (Exception exception)
+                {
+                    if (IsWrappedException(exception))
+                    {
+                        throw;
+                    }
+
+                    WrapAndThrowException(exception);
+                }
+                finally
+                {
+                    PacketFormatterAdapter.FreeBuffer();
+                }
+            }
+        }
+
+        public async Task<MqttBasePacket> ReceivePacketAsync(CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
            ThrowIfDisposed();

            try
            {
-                using (await _syncRoot.WaitAsync(cancellationToken).ConfigureAwait(false))
-                {
-                    // Check for cancellation here again because "WaitAsync" might take some time.
-                    cancellationToken.ThrowIfCancellationRequested();
+                _packetInspectorHandler.BeginReceivePacket();

-                    try
-                    {
-                        var packetData = PacketFormatterAdapter.Encode(packet);
-
-                        if (timeout == TimeSpan.Zero)
-                        {
-                            await _channel.WriteAsync(packetData.Array, packetData.Offset, packetData.Count, cancellationToken).ConfigureAwait(false);
-                        }
-                        else
-                        {
-                            await MqttTaskTimeout.WaitAsync(
-                                t => _channel.WriteAsync(packetData.Array, packetData.Offset, packetData.Count, t), timeout, cancellationToken).ConfigureAwait(false);
-                        }
-
-                        Interlocked.Add(ref _bytesReceived, packetData.Count);
-
-                        _logger.Verbose("TX ({0} bytes) >>> {1}", packetData.Count, packet);
-                    }
-                    catch (Exception exception)
-                    {
-                        if (IsWrappedException(exception))
-                        {
-                            throw;
-                        }
-
-                        WrapException(exception);
-                    }
-                    finally
-                    {
-                        PacketFormatterAdapter.FreeBuffer();
-                    }
-                }
-            }
-            catch (ObjectDisposedException)
-            {
-                throw new OperationCanceledException();
-            }
-        }
-
-        public async Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout, 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);
-                }
-
-                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;
            }
@@ -214,7 +196,7 @@ namespace MQTTnet.Adapter
                    throw;
                }

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

            return null;
@@ -239,31 +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
                {
@@ -286,25 +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)
            {
@@ -313,11 +403,15 @@ 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)
@@ -1,17 +1,19 @@
-using MQTTnet.Client.Connecting;
+using System;
+using MQTTnet.Client.Connecting;
 using MQTTnet.Exceptions;

 namespace MQTTnet.Adapter
 {
-    public class MqttConnectingFailedException : MqttCommunicationException
+    public sealed class MqttConnectingFailedException : MqttCommunicationException
    {
-        public MqttConnectingFailedException(MqttClientAuthenticateResult result)
-            : base($"Connecting with MQTT server failed ({result.ResultCode.ToString()}).")
+        public MqttConnectingFailedException(string message, Exception innerException, MqttClientAuthenticateResult authenticateResult)
+            : base(message, innerException)
        {
-            Result = result;
+            Result = authenticateResult;
        }

        public MqttClientAuthenticateResult Result { get; }
-        public MqttClientConnectResultCode ResultCode => Result.ResultCode;
+
+        public MqttClientConnectResultCode ResultCode => Result?.ResultCode ?? MqttClientConnectResultCode.UnspecifiedError;
    }
 }
@@ -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; }
    }
@@ -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; }
    }
 }
@@ -12,7 +12,7 @@
        ServerBusy = 137,
        ServerShuttingDown = 139,
        BadAuthenticationMethod = 140,
-        KeepaliveTimeout = 141,
+        KeepAliveTimeout = 141,
        SessionTakenOver = 142,
        TopicFilterInvalid = 143,
        TopicNameInvalid = 144,
@@ -3,22 +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, MqttClientDisconnectReason reasonCode)
+        public MqttClientDisconnectedEventArgs(bool clientWasConnected, Exception exception, MqttClientAuthenticateResult authenticateResult, MqttClientDisconnectReason reason)
        {
            ClientWasConnected = clientWasConnected;
            Exception = exception;
            AuthenticateResult = authenticateResult;
-            ReasonCode = reasonCode;
+            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; }

-        public MqttClientDisconnectReason ReasonCode { get; set; } = MqttClientDisconnectReason.NormalDisconnection;
+        /// <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 +1,4 @@
-using System;
-using MQTTnet.Adapter;
+using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
 using MQTTnet.LowLevelClient;

@@ -14,9 +14,9 @@ using MQTTnet.PacketDispatcher;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
 using System;
-using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Implementations;

 namespace MQTTnet.Client
 {
@@ -24,8 +24,6 @@ namespace MQTTnet.Client
    {
        readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
        readonly MqttPacketDispatcher _packetDispatcher = new MqttPacketDispatcher();
-        readonly Stopwatch _sendTracker = new Stopwatch();
-        readonly Stopwatch _receiveTracker = new Stopwatch();
        readonly object _disconnectLock = new object();

        readonly IMqttClientAdapterFactory _adapterFactory;
@@ -42,6 +40,9 @@ namespace MQTTnet.Client
        bool _cleanDisconnectInitiated;
        long _isDisconnectPending;
        bool _isConnected;
+        MqttClientDisconnectReason _disconnectReason;
+        
+        DateTime _lastPacketSentTimestamp;

        public MqttClient(IMqttClientAdapterFactory channelFactory, IMqttNetLogger logger)
        {
@@ -77,7 +78,7 @@ namespace MQTTnet.Client
                Options = options;

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

                _backgroundCancellationTokenSource = new CancellationTokenSource();
                var backgroundCancellationToken = _backgroundCancellationTokenSource.Token;
@@ -88,8 +89,8 @@ 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>();
@@ -100,8 +101,7 @@ namespace MQTTnet.Client
                    authenticateResult = await AuthenticateAsync(adapter, options.WillMessage, combined.Token).ConfigureAwait(false);
                }

-                _sendTracker.Restart();
-                _receiveTracker.Restart();
+                _lastPacketSentTimestamp = DateTime.UtcNow;

                if (Options.KeepAlivePeriod != TimeSpan.Zero)
                {
@@ -122,6 +122,8 @@ namespace MQTTnet.Client
            }
            catch (Exception exception)
            {
+                _disconnectReason = MqttClientDisconnectReason.UnspecifiedError;
+
                _logger.Error(exception, "Error while connecting with server.");

                if (!DisconnectIsPending())
@@ -139,11 +141,17 @@ 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);
@@ -151,16 +159,13 @@ namespace MQTTnet.Client
            }
            finally
            {
-                if (!DisconnectIsPending())
-                {
-                    await DisconnectInternalAsync(null, null, null).ConfigureAwait(false);
-                }
+                await DisconnectInternalAsync(null, null, null).ConfigureAwait(false);
            }
        }

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

        public Task SendExtendedAuthenticationExchangeDataAsync(MqttExtendedAuthenticationExchangeData data, CancellationToken cancellationToken)
@@ -213,9 +218,9 @@ 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();
@@ -266,8 +271,6 @@ namespace MQTTnet.Client
            if (disposing)
            {
                Cleanup();
-
-                DisconnectedHandler = null;
            }

            base.Dispose(disposing);
@@ -275,16 +278,25 @@ namespace MQTTnet.Client

        async Task<MqttClientAuthenticateResult> AuthenticateAsync(IMqttChannelAdapter channelAdapter, MqttApplicationMessage willApplicationMessage, CancellationToken cancellationToken)
        {
-            var connectPacket = channelAdapter.PacketFormatterAdapter.DataConverter.CreateConnectPacket(
-                willApplicationMessage,
-                Options);
+            MqttClientAuthenticateResult result;

-            var connAckPacket = await SendAndReceiveAsync<MqttConnAckPacket>(connectPacket, cancellationToken).ConfigureAwait(false);
-            var result = channelAdapter.PacketFormatterAdapter.DataConverter.CreateClientConnectResult(connAckPacket);
+            try
+            {
+                var connectPacket = channelAdapter.PacketFormatterAdapter.DataConverter.CreateConnectPacket(
+                    willApplicationMessage,
+                    Options);
+
+                var connAckPacket = await SendAndReceiveAsync<MqttConnAckPacket>(connectPacket, cancellationToken).ConfigureAwait(false);
+                result = channelAdapter.PacketFormatterAdapter.DataConverter.CreateClientConnectResult(connAckPacket);
+            }
+            catch (Exception exception)
+            {
+                throw new MqttConnectingFailedException($"Error while authenticating. {exception.Message}", exception, null);
+            }

            if (result.ResultCode != MqttClientConnectResultCode.Success)
            {
-                throw new MqttConnectingFailedException(result);
+                throw new MqttConnectingFailedException($"Connecting with MQTT server failed ({result.ResultCode}).", null, result);
            }

            _logger.Verbose("Authenticated MQTT connection with server established.");
@@ -308,7 +320,6 @@ namespace MQTTnet.Client
        async Task DisconnectInternalAsync(Task sender, Exception exception, MqttClientAuthenticateResult authenticateResult)
        {
            var clientWasConnected = _isConnected;
-            var reasonCode = MqttClientDisconnectReason.NormalDisconnection;

            TryInitiateDisconnect();
            _isConnected = false;
@@ -326,7 +337,6 @@ namespace MQTTnet.Client
            catch (Exception adapterException)
            {
                _logger.Warning(adapterException, "Error while disconnecting from adapter.");
-                reasonCode = MqttClientDisconnectReason.UnspecifiedError;
            }

            try
@@ -342,7 +352,6 @@ namespace MQTTnet.Client
            catch (Exception e)
            {
                _logger.Warning(e, "Error while waiting for internal tasks.");
-                reasonCode = MqttClientDisconnectReason.UnspecifiedError;
            }
            finally
            {
@@ -356,7 +365,7 @@ 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, reasonCode))).Forget(_logger);
+                    Task.Run(() => disconnectedHandler.HandleDisconnectedAsync(new MqttClientDisconnectedEventArgs(clientWasConnected, exception, authenticateResult, _disconnectReason))).RunInBackground(_logger);
                }
            }
        }
@@ -367,11 +376,6 @@ namespace MQTTnet.Client
            {
                try
                {
-                    if (_backgroundCancellationTokenSource?.IsCancellationRequested == true)
-                    {
-                        return;
-                    }
-
                    _backgroundCancellationTokenSource?.Cancel(false);
                }
                catch (Exception exception)
@@ -385,33 +389,31 @@ namespace MQTTnet.Client
        {
            cancellationToken.ThrowIfCancellationRequested();

-            _sendTracker.Restart();
-
-            return _adapter.SendPacketAsync(packet, Options.CommunicationTimeout, cancellationToken);
+            _lastPacketSentTimestamp = DateTime.UtcNow;
+            
+            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)
+            ushort packetIdentifier = 0;
+            if (requestPacket is IMqttPacketWithIdentifier packetWithIdentifier)
            {
-                identifier = packetWithIdentifier.PacketIdentifier.Value;
+                packetIdentifier = packetWithIdentifier.PacketIdentifier;
            }

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

                try
@@ -422,7 +424,7 @@ 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;
@@ -441,15 +443,15 @@ namespace MQTTnet.Client
                while (!cancellationToken.IsCancellationRequested)
                {
                    // Values described here: [MQTT-3.1.2-24].
-                    var waitTime = keepAlivePeriod - _sendTracker.Elapsed;
+                    var timeWithoutPacketSent = DateTime.UtcNow - _lastPacketSentTimestamp;

-                    if (waitTime <= TimeSpan.Zero)
+                    if (timeWithoutPacketSent > keepAlivePeriod)
                    {
-                        await SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket(), cancellationToken).ConfigureAwait(false);
+                        await PingAsync(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
+                    // due to some edge cases and was buggy in the past. Now we wait several ms 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);
@@ -464,6 +466,7 @@ namespace MQTTnet.Client

                if (exception is OperationCanceledException)
                {
+                    return;
                }
                else if (exception is MqttCommunicationException)
                {
@@ -493,7 +496,7 @@ 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)
                    {
@@ -532,7 +535,7 @@ namespace MQTTnet.Client
                    _logger.Error(exception, "Error while receiving packets.");
                }

-                _packetDispatcher.Dispatch(exception);
+                _packetDispatcher.FailAll(exception);

                if (!DisconnectIsPending())
                {
@@ -549,45 +552,40 @@ namespace MQTTnet.Client
        {
            try
            {
-                _receiveTracker.Restart();
-
                if (packet is MqttPublishPacket publishPacket)
                {
                    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);
-                }
-                else if (packet is MqttPingReqPacket)
-                {
-                    await SendAsync(new MqttPingRespPacket(), cancellationToken).ConfigureAwait(false);
+                    await ProcessReceivedPubRelPacket(pubRelPacket, cancellationToken).ConfigureAwait(false);
                }
                else if (packet is MqttDisconnectPacket disconnectPacket)
                {
-                    // Also dispatch disconnect to waiting threads to generate a proper exception.
-                    _packetDispatcher.Dispatch(packet);
-
-                    await DisconnectAsync(new MqttClientDisconnectOptions()
-                    {
-                        ReasonCode = (MqttClientDisconnectReason)(disconnectPacket.ReasonCode ?? MqttDisconnectReasonCode.UnspecifiedError)
-                    }, 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 if (packet is MqttPingRespPacket)
+                {
+                    _packetDispatcher.TryDispatch(packet);
+                }
+                else if (packet is MqttPingReqPacket)
+                {
+                    throw new MqttProtocolViolationException("The PINGREQ Packet is sent from a Client to the Server only.");
                }
                else
                {
-                    _packetDispatcher.Dispatch(packet);
+                    if (!_packetDispatcher.TryDispatch(packet))
+                    {
+                        throw new MqttProtocolViolationException($"Received packet '{packet}' at an unexpected time.");
+                    }
                }
            }
            catch (Exception exception)
@@ -609,7 +607,7 @@ namespace MQTTnet.Client
                    _logger.Error(exception, "Error while receiving packets.");
                }

-                _packetDispatcher.Dispatch(exception);
+                _packetDispatcher.FailAll(exception);

                if (!DisconnectIsPending())
                {
@@ -626,7 +624,7 @@ namespace MQTTnet.Client
            }
            catch (Exception exception)
            {
-                _logger.Error(exception, "Error while enqueueing application message.");
+                _logger.Error(exception, "Error while queueing application message.");
            }
        }

@@ -636,7 +634,7 @@ namespace MQTTnet.Client
            {
                try
                {
-                    var publishPacketDequeueResult = await _publishPacketReceiverQueue.TryDequeueAsync(cancellationToken);
+                    var publishPacketDequeueResult = await _publishPacketReceiverQueue.TryDequeueAsync(cancellationToken).ConfigureAwait(false);
                    if (!publishPacketDequeueResult.IsSuccess)
                    {
                        return;
@@ -650,25 +648,21 @@ 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
-                            }, cancellationToken).ConfigureAwait(false);
+                            var pubAckPacket = _adapter.PacketFormatterAdapter.DataConverter.CreatePubAckPacket(publishPacket, eventArgs.ReasonCode);
+                            await SendAsync(pubAckPacket, cancellationToken).ConfigureAwait(false);
                        }
                    }
                    else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.ExactlyOnce)
                    {
-                        if (await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false))
-                        {
-                            var pubRecPacket = new MqttPubRecPacket
-                            {
-                                PacketIdentifier = publishPacket.PacketIdentifier,
-                                ReasonCode = MqttPubRecReasonCode.Success
-                            };
+                        var eventArgs = await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false);

+                        if (!eventArgs.ProcessingFailed)
+                        {
+                            var pubRecPacket = _adapter.PacketFormatterAdapter.DataConverter.CreatePubRecPacket(publishPacket, eventArgs.ReasonCode);
                            await SendAsync(pubRecPacket, cancellationToken).ConfigureAwait(false);
                        }
                    }
@@ -677,6 +671,9 @@ 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.");
@@ -684,18 +681,63 @@ 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.
+                var pubRelPacket = _adapter.PacketFormatterAdapter.DataConverter.CreatePubRelPacket(pubRecPacket, MqttApplicationMessageReceivedReasonCode.PacketIdentifierNotFound);
+                return SendAsync(pubRelPacket, cancellationToken);
+            }
+
+            return PlatformAbstractionLayer.CompletedTask;
+        }
+
+        Task ProcessReceivedPubRelPacket(MqttPubRelPacket pubRelPacket, CancellationToken cancellationToken)
+        {
+            var pubCompPacket = _adapter.PacketFormatterAdapter.DataConverter.CreatePubCompPacket(pubRelPacket, MqttApplicationMessageReceivedReasonCode.Success);
+            return SendAsync(pubCompPacket, cancellationToken);
+        }
+
+        Task ProcessReceivedDisconnectPacket(MqttDisconnectPacket disconnectPacket)
+        {
+            _disconnectReason = (MqttClientDisconnectReason)(disconnectPacket.ReasonCode ?? MqttDisconnectReasonCode.NormalDisconnection);
+
+            // Also dispatch disconnect to waiting threads to generate a proper exception.
+            _packetDispatcher.FailAll(new MqttUnexpectedDisconnectReceivedException(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]
            await SendAsync(publishPacket, cancellationToken).ConfigureAwait(false);
-            return _adapter.PacketFormatterAdapter.DataConverter.CreatePublishResult(null);
+            return _adapter.PacketFormatterAdapter.DataConverter.CreateClientPublishResult(null);
        }

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

        async Task<MqttClientPublishResult> PublishExactlyOnceAsync(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
@@ -704,30 +746,25 @@ namespace MQTTnet.Client

            var pubRecPacket = await SendAndReceiveAsync<MqttPubRecPacket>(publishPacket, cancellationToken).ConfigureAwait(false);

-            var pubRelPacket = new MqttPubRelPacket
-            {
-                PacketIdentifier = publishPacket.PacketIdentifier,
-                ReasonCode = MqttPubRelReasonCode.Success
-            };
-
+            var pubRelPacket = _adapter.PacketFormatterAdapter.DataConverter.CreatePubRelPacket(pubRecPacket, MqttApplicationMessageReceivedReasonCode.Success);
+            
            var pubCompPacket = await SendAndReceiveAsync<MqttPubCompPacket>(pubRelPacket, cancellationToken).ConfigureAwait(false);

-            return _adapter.PacketFormatterAdapter.DataConverter.CreatePublishResult(pubRecPacket, pubCompPacket);
+            return _adapter.PacketFormatterAdapter.DataConverter.CreateClientPublishResult(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)
@@ -763,6 +800,8 @@ 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)
@@ -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; }
@@ -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; }

@@ -26,7 +26,11 @@ namespace MQTTnet.Client.Options
        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; }
+    }
+}
@@ -22,6 +22,8 @@
                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;

@@ -12,30 +14,40 @@ namespace MQTTnet.Formatter
 {
    public interface IMqttDataConverter
    {
-        MqttPublishPacket CreatePublishPacket(MqttApplicationMessage applicationMessage);
-
-        MqttPubAckPacket CreatePubAckPacket(MqttPublishPacket publishPacket);
-
        MqttApplicationMessage CreateApplicationMessage(MqttPublishPacket publishPacket);

        MqttClientAuthenticateResult CreateClientConnectResult(MqttConnAckPacket connAckPacket);

+        MqttClientPublishResult CreateClientPublishResult(MqttPubAckPacket pubAckPacket);
+
+        MqttClientPublishResult CreateClientPublishResult(MqttPubRecPacket pubRecPacket, MqttPubCompPacket pubCompPacket);
+        
+        MqttClientSubscribeResult CreateClientSubscribeResult(MqttSubscribePacket subscribePacket, MqttSubAckPacket subAckPacket);
+        
+        MqttClientUnsubscribeResult CreateClientUnsubscribeResult(MqttUnsubscribePacket unsubscribePacket, MqttUnsubAckPacket unsubAckPacket);
+
        MqttConnectPacket CreateConnectPacket(MqttApplicationMessage willApplicationMessage, IMqttClientOptions options);

        MqttConnAckPacket CreateConnAckPacket(MqttConnectionValidatorContext connectionValidatorContext);
+        
+        MqttPublishPacket CreatePublishPacket(MqttApplicationMessage applicationMessage);

-        MqttClientSubscribeResult CreateClientSubscribeResult(MqttSubscribePacket subscribePacket, MqttSubAckPacket subAckPacket);
-
-        MqttClientUnsubscribeResult CreateClientUnsubscribeResult(MqttUnsubscribePacket unsubscribePacket, MqttUnsubAckPacket unsubAckPacket);
+        MqttPubAckPacket CreatePubAckPacket(MqttPublishPacket publishPacket, MqttApplicationMessageReceivedReasonCode reasonCode);
+        
+        MqttPubRecPacket CreatePubRecPacket(MqttPublishPacket publishPacket, MqttApplicationMessageReceivedReasonCode reasonCode);

+        MqttPubCompPacket CreatePubCompPacket(MqttPubRelPacket pubRelPacket, MqttApplicationMessageReceivedReasonCode reasonCode);
+        
+        MqttPubRelPacket CreatePubRelPacket(MqttPubRecPacket pubRecPacket, MqttApplicationMessageReceivedReasonCode reasonCode);
+        
        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);
-
-        MqttClientPublishResult CreatePublishResult(MqttPubRecPacket pubRecPacket, MqttPubCompPacket pubCompPacket);
    }
 }
@@ -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)
        {
@@ -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:
@@ -116,11 +105,22 @@ 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));

-            if (receivedMqttPacket.Body.Length < 7)
+            if (receivedMqttPacket.BodyReader.Length < 7)
            {
                // 2 byte protocol name length
                // at least 4 byte protocol name
@@ -128,8 +128,8 @@ namespace MQTTnet.Formatter
                throw new MqttProtocolViolationException("CONNECT packet must have at least 7 bytes.");
            }

-            var protocolName = receivedMqttPacket.Body.ReadStringWithLengthPrefix();
-            var protocolLevel = receivedMqttPacket.Body.ReadByte();
+            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;

@@ -30,12 +31,43 @@ namespace MQTTnet.Formatter.V3
            };
        }

-        public MqttPubAckPacket CreatePubAckPacket(MqttPublishPacket publishPacket)
+        public MqttPubAckPacket CreatePubAckPacket(MqttPublishPacket publishPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
        {
+            if (publishPacket == null) throw new ArgumentNullException(nameof(publishPacket));
+            
            return new MqttPubAckPacket
            {
-                PacketIdentifier = publishPacket.PacketIdentifier,
-                ReasonCode = MqttPubAckReasonCode.Success
+                PacketIdentifier = publishPacket.PacketIdentifier
+            };
+        }
+
+        public MqttPubRecPacket CreatePubRecPacket(MqttPublishPacket publishPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
+        {
+            if (publishPacket == null) throw new ArgumentNullException(nameof(publishPacket));
+            
+            return new MqttPubRecPacket
+            {
+                PacketIdentifier = publishPacket.PacketIdentifier
+            };
+        }
+
+        public MqttPubCompPacket CreatePubCompPacket(MqttPubRelPacket pubRelPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
+        {
+            if (pubRelPacket == null) throw new ArgumentNullException(nameof(pubRelPacket));
+            
+            return new MqttPubCompPacket
+            {
+                PacketIdentifier = pubRelPacket.PacketIdentifier
+            };
+        }
+
+        public MqttPubRelPacket CreatePubRelPacket(MqttPubRecPacket pubRecPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
+        {
+            if (pubRecPacket == null) throw new ArgumentNullException(nameof(pubRecPacket));
+            
+            return new MqttPubRelPacket
+            {
+                PacketIdentifier = pubRecPacket.PacketIdentifier
            };
        }

@@ -48,7 +80,8 @@ namespace MQTTnet.Formatter.V3
                Topic = publishPacket.Topic,
                Payload = publishPacket.Payload,
                QualityOfServiceLevel = publishPacket.QualityOfServiceLevel,
-                Retain = publishPacket.Retain
+                Retain = publishPacket.Retain,
+                Dup = publishPacket.Dup
            };
        }

@@ -172,6 +205,21 @@ namespace MQTTnet.Formatter.V3
            return subscribePacket;
        }

+        public MqttSubAckPacket CreateSubAckPacket(MqttSubscribePacket subscribePacket, Server.MqttClientSubscribeResult subscribeResult)
+        {
+            if (subscribePacket == null) throw new ArgumentNullException(nameof(subscribePacket));
+            if (subscribeResult == null) throw new ArgumentNullException(nameof(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 +230,18 @@ namespace MQTTnet.Formatter.V3
            return unsubscribePacket;
        }

+        public MqttUnsubAckPacket CreateUnsubAckPacket(MqttUnsubscribePacket unsubscribePacket, List<MqttUnsubscribeReasonCode> reasonCodes)
+        {
+            if (unsubscribePacket == null) throw new ArgumentNullException(nameof(unsubscribePacket));
+            if (reasonCodes == null) throw new ArgumentNullException(nameof(reasonCodes));
+
+            return new MqttUnsubAckPacket
+            {
+                PacketIdentifier = unsubscribePacket.PacketIdentifier,
+                ReasonCodes = reasonCodes
+            };
+        }
+
        public MqttDisconnectPacket CreateDisconnectPacket(MqttClientDisconnectOptions options)
        {
            if (options.ReasonCode != MqttClientDisconnectReason.NormalDisconnection || options.ReasonString != null)
@@ -192,7 +252,7 @@ namespace MQTTnet.Formatter.V3
            return new MqttDisconnectPacket();
        }

-        public MqttClientPublishResult CreatePublishResult(MqttPubAckPacket pubAckPacket)
+        public MqttClientPublishResult CreateClientPublishResult(MqttPubAckPacket pubAckPacket)
        {
            return new MqttClientPublishResult
            {
@@ -201,7 +261,7 @@ namespace MQTTnet.Formatter.V3
            };
        }

-        public MqttClientPublishResult CreatePublishResult(MqttPubRecPacket pubRecPacket, MqttPubCompPacket pubCompPacket)
+        public MqttClientPublishResult CreateClientPublishResult(MqttPubRecPacket pubRecPacket, MqttPubCompPacket pubCompPacket)
        {
            if (pubRecPacket == null || pubCompPacket == null)
            {
@@ -63,20 +63,20 @@ namespace MQTTnet.Formatter.V3

            switch ((MqttControlPacketType)controlPacketType)
            {
-                case MqttControlPacketType.Connect: return DecodeConnectPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.ConnAck: return DecodeConnAckPacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.Connect: return DecodeConnectPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.ConnAck: return DecodeConnAckPacket(receivedMqttPacket.BodyReader);
                case MqttControlPacketType.Disconnect: return DisconnectPacket;
                case MqttControlPacketType.Publish: return DecodePublishPacket(receivedMqttPacket);
-                case MqttControlPacketType.PubAck: return DecodePubAckPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.PubRec: return DecodePubRecPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.PubRel: return DecodePubRelPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.PubComp: return DecodePubCompPacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.PubAck: return DecodePubAckPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.PubRec: return DecodePubRecPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.PubRel: return DecodePubRelPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.PubComp: return DecodePubCompPacket(receivedMqttPacket.BodyReader);
                case MqttControlPacketType.PingReq: return PingReqPacket;
                case MqttControlPacketType.PingResp: return PingRespPacket;
-                case MqttControlPacketType.Subscribe: return DecodeSubscribePacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.SubAck: return DecodeSubAckPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.Unsubscibe: return DecodeUnsubscribePacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.UnsubAck: return DecodeUnsubAckPacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.Subscribe: return DecodeSubscribePacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.SubAck: return DecodeSubAckPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.Unsubscibe: return DecodeUnsubscribePacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.UnsubAck: return DecodeUnsubAckPacket(receivedMqttPacket.BodyReader);

                default: throw new MqttProtocolViolationException($"Packet type ({controlPacketType}) not supported.");
            }
@@ -202,18 +202,18 @@ namespace MQTTnet.Formatter.V3

        static MqttBasePacket DecodePublishPacket(ReceivedMqttPacket receivedMqttPacket)
        {
-            ThrowIfBodyIsEmpty(receivedMqttPacket.Body);
+            ThrowIfBodyIsEmpty(receivedMqttPacket.BodyReader);

            var retain = (receivedMqttPacket.FixedHeader & 0x1) > 0;
            var qualityOfServiceLevel = (MqttQualityOfServiceLevel)(receivedMqttPacket.FixedHeader >> 1 & 0x3);
            var dup = (receivedMqttPacket.FixedHeader & 0x8) > 0;

-            var topic = receivedMqttPacket.Body.ReadStringWithLengthPrefix();
+            var topic = receivedMqttPacket.BodyReader.ReadStringWithLengthPrefix();

-            ushort? packetIdentifier = null;
+            ushort packetIdentifier = 0;
            if (qualityOfServiceLevel > MqttQualityOfServiceLevel.AtMostOnce)
            {
-                packetIdentifier = receivedMqttPacket.Body.ReadTwoByteInteger();
+                packetIdentifier = receivedMqttPacket.BodyReader.ReadTwoByteInteger();
            }

            var packet = new MqttPublishPacket
@@ -225,9 +225,9 @@ namespace MQTTnet.Formatter.V3
                Dup = dup
            };

-            if (!receivedMqttPacket.Body.EndOfStream)
+            if (!receivedMqttPacket.BodyReader.EndOfStream)
            {
-                packet.Payload = receivedMqttPacket.Body.ReadRemainingData();
+                packet.Payload = receivedMqttPacket.BodyReader.ReadRemainingData();
            }

            return packet;
@@ -414,12 +414,12 @@ namespace MQTTnet.Formatter.V3

        static byte EncodePubRelPacket(MqttPubRelPacket packet, IMqttPacketWriter packetWriter)
        {
-            if (!packet.PacketIdentifier.HasValue)
+            if (packet.PacketIdentifier == 0)
            {
                throw new MqttProtocolViolationException("PubRel packet has no packet identifier.");
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubRel, 0x02);
        }
@@ -432,12 +432,12 @@ namespace MQTTnet.Formatter.V3

            if (packet.QualityOfServiceLevel > MqttQualityOfServiceLevel.AtMostOnce)
            {
-                if (!packet.PacketIdentifier.HasValue)
+                if (packet.PacketIdentifier == 0)
                {
                    throw new MqttProtocolViolationException("Publish packet has no packet identifier.");
                }

-                packetWriter.Write(packet.PacketIdentifier.Value);
+                packetWriter.Write(packet.PacketIdentifier);
            }
            else
            {
@@ -471,36 +471,36 @@ namespace MQTTnet.Formatter.V3

        static byte EncodePubAckPacket(MqttPubAckPacket packet, IMqttPacketWriter packetWriter)
        {
-            if (!packet.PacketIdentifier.HasValue)
+            if (packet.PacketIdentifier == 0)
            {
                throw new MqttProtocolViolationException("PubAck packet has no packet identifier.");
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubAck);
        }

        static byte EncodePubRecPacket(MqttPubRecPacket packet, IMqttPacketWriter packetWriter)
        {
-            if (!packet.PacketIdentifier.HasValue)
+            if (packet.PacketIdentifier == 0)
            {
                throw new MqttProtocolViolationException("PubRec packet has no packet identifier.");
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubRec);
        }

        static byte EncodePubCompPacket(MqttPubCompPacket packet, IMqttPacketWriter packetWriter)
        {
-            if (!packet.PacketIdentifier.HasValue)
+            if (packet.PacketIdentifier == 0)
            {
                throw new MqttProtocolViolationException("PubComp packet has no packet identifier.");
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubComp);
        }
@@ -509,12 +509,12 @@ namespace MQTTnet.Formatter.V3
        {
            if (!packet.TopicFilters.Any()) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.8.3-3].");

-            if (!packet.PacketIdentifier.HasValue)
+            if (packet.PacketIdentifier == 0)
            {
                throw new MqttProtocolViolationException("Subscribe packet has no packet identifier.");
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            if (packet.TopicFilters?.Count > 0)
            {
@@ -530,12 +530,12 @@ namespace MQTTnet.Formatter.V3

        static byte EncodeSubAckPacket(MqttSubAckPacket packet, IMqttPacketWriter packetWriter)
        {
-            if (!packet.PacketIdentifier.HasValue)
+            if (packet.PacketIdentifier == 0)
            {
                throw new MqttProtocolViolationException("SubAck packet has no packet identifier.");
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            if (packet.ReturnCodes?.Any() == true)
            {
@@ -552,12 +552,12 @@ namespace MQTTnet.Formatter.V3
        {
            if (!packet.TopicFilters.Any()) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.10.3-2].");

-            if (!packet.PacketIdentifier.HasValue)
+            if (packet.PacketIdentifier == 0)
            {
                throw new MqttProtocolViolationException("Unsubscribe packet has no packet identifier.");
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            if (packet.TopicFilters?.Any() == true)
            {
@@ -572,12 +572,12 @@ namespace MQTTnet.Formatter.V3

        static byte EncodeUnsubAckPacket(MqttUnsubAckPacket packet, IMqttPacketWriter packetWriter)
        {
-            if (!packet.PacketIdentifier.HasValue)
+            if (packet.PacketIdentifier == 0)
            {
                throw new MqttProtocolViolationException("UnsubAck packet has no packet identifier.");
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.UnsubAck);
        }

@@ -4,7 +4,7 @@ using MQTTnet.Protocol;

 namespace MQTTnet.Formatter.V3
 {
-    public class MqttV311PacketFormatter : MqttV310PacketFormatter
+    public sealed class MqttV311PacketFormatter : MqttV310PacketFormatter
    {
        public MqttV311PacketFormatter(IMqttPacketWriter packetWriter)
            : base(packetWriter)
@@ -15,7 +15,7 @@ using MqttClientSubscribeResult = MQTTnet.Client.Subscribing.MqttClientSubscribe

 namespace MQTTnet.Formatter.V5
 {
-    public class MqttV500DataConverter : IMqttDataConverter
+    public sealed class MqttV500DataConverter : IMqttDataConverter
    {
        public MqttPublishPacket CreatePublishPacket(MqttApplicationMessage applicationMessage)
        {
@@ -27,7 +27,7 @@ namespace MQTTnet.Formatter.V5
                Payload = applicationMessage.Payload,
                QualityOfServiceLevel = applicationMessage.QualityOfServiceLevel,
                Retain = applicationMessage.Retain,
-                Dup = false,
+                Dup = applicationMessage.Dup,
                Properties = new MqttPublishPacketProperties
                {
                    ContentType = applicationMessage.ContentType,
@@ -49,23 +49,61 @@ namespace MQTTnet.Formatter.V5
            return packet;
        }

-        public MqttPubAckPacket CreatePubAckPacket(MqttPublishPacket publishPacket)
+        public MqttPubAckPacket CreatePubAckPacket(MqttPublishPacket publishPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
        {
+            if (publishPacket == null) throw new ArgumentNullException(nameof(publishPacket));
+
            return new MqttPubAckPacket
            {
                PacketIdentifier = publishPacket.PacketIdentifier,
-                ReasonCode = MqttPubAckReasonCode.Success
+                ReasonCode = (MqttPubAckReasonCode)(int)reasonCode
+            };
+        }
+
+        public MqttPubRecPacket CreatePubRecPacket(MqttPublishPacket publishPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
+        {
+            if (publishPacket == null) throw new ArgumentNullException(nameof(publishPacket));
+
+            return new MqttPubRecPacket
+            {
+                PacketIdentifier = publishPacket.PacketIdentifier,
+                ReasonCode = (MqttPubRecReasonCode)(int)reasonCode
+            };
+        }
+
+        public MqttPubCompPacket CreatePubCompPacket(MqttPubRelPacket pubRelPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
+        {
+            if (pubRelPacket == null) throw new ArgumentNullException(nameof(pubRelPacket));
+
+            return new MqttPubCompPacket
+            {
+                PacketIdentifier = pubRelPacket.PacketIdentifier,
+                ReasonCode = (MqttPubCompReasonCode)(int)reasonCode
+            };
+        }
+
+        public MqttPubRelPacket CreatePubRelPacket(MqttPubRecPacket pubRecPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
+        {
+            if (pubRecPacket == null) throw new ArgumentNullException(nameof(pubRecPacket));
+
+            return new MqttPubRelPacket
+            {
+                PacketIdentifier = pubRecPacket.PacketIdentifier,
+                ReasonCode = (MqttPubRelReasonCode)(int)reasonCode
            };
        }

        public MqttApplicationMessage CreateApplicationMessage(MqttPublishPacket publishPacket)
        {
+            if (publishPacket == null) throw new ArgumentNullException(nameof(publishPacket));
+
            return new MqttApplicationMessage
            {
                Topic = publishPacket.Topic,
                Payload = publishPacket.Payload,
                QualityOfServiceLevel = publishPacket.QualityOfServiceLevel,
                Retain = publishPacket.Retain,
+                Dup = publishPacket.Dup,
                ResponseTopic = publishPacket.Properties?.ResponseTopic,
                ContentType = publishPacket.Properties?.ContentType,
                CorrelationData = publishPacket.Properties?.CorrelationData,
@@ -84,7 +122,7 @@ namespace MQTTnet.Formatter.V5
            return new MqttClientAuthenticateResult
            {
                IsSessionPresent = connAckPacket.IsSessionPresent,
-                ResultCode = (MqttClientConnectResultCode)connAckPacket.ReasonCode.Value,
+                ResultCode = (MqttClientConnectResultCode)(int)(connAckPacket.ReasonCode ?? 0),
                WildcardSubscriptionAvailable = connAckPacket.Properties?.WildcardSubscriptionAvailable,
                RetainAvailable = connAckPacket.Properties?.RetainAvailable,
                AssignedClientIdentifier = connAckPacket.Properties?.AssignedClientIdentifier,
@@ -93,6 +131,7 @@ namespace MQTTnet.Formatter.V5
                MaximumPacketSize = connAckPacket.Properties?.MaximumPacketSize,
                ReasonString = connAckPacket.Properties?.ReasonString,
                ReceiveMaximum = connAckPacket.Properties?.ReceiveMaximum,
+                MaximumQoS = connAckPacket.Properties?.MaximumQoS ?? MqttQualityOfServiceLevel.ExactlyOnce,
                ResponseInformation = connAckPacket.Properties?.ResponseInformation,
                TopicAliasMaximum = connAckPacket.Properties?.TopicAliasMaximum,
                ServerReference = connAckPacket.Properties?.ServerReference,
@@ -134,6 +173,8 @@ namespace MQTTnet.Formatter.V5

        public MqttConnAckPacket CreateConnAckPacket(MqttConnectionValidatorContext connectionValidatorContext)
        {
+            if (connectionValidatorContext == null) throw new ArgumentNullException(nameof(connectionValidatorContext));
+
            return new MqttConnAckPacket
            {
                ReasonCode = connectionValidatorContext.ReasonCode,
@@ -143,7 +184,8 @@ namespace MQTTnet.Formatter.V5
                    AuthenticationMethod = connectionValidatorContext.AuthenticationMethod,
                    AuthenticationData = connectionValidatorContext.ResponseAuthenticationData,
                    AssignedClientIdentifier = connectionValidatorContext.AssignedClientIdentifier,
-                    ReasonString = connectionValidatorContext.ReasonString
+                    ReasonString = connectionValidatorContext.ReasonString,
+                    TopicAliasMaximum = ushort.MaxValue
                }
            };
        }
@@ -200,6 +242,21 @@ namespace MQTTnet.Formatter.V5
            return packet;
        }

+        public MqttSubAckPacket CreateSubAckPacket(MqttSubscribePacket subscribePacket, Server.MqttClientSubscribeResult subscribeResult)
+        {
+            if (subscribePacket == null) throw new ArgumentNullException(nameof(subscribePacket));
+            if (subscribeResult == null) throw new ArgumentNullException(nameof(subscribeResult));
+
+            var subackPacket = new MqttSubAckPacket
+            {
+                PacketIdentifier = subscribePacket.PacketIdentifier
+            };
+
+            subackPacket.ReasonCodes.AddRange(subscribeResult.ReasonCodes);
+
+            return subackPacket;
+        }
+
        public MqttUnsubscribePacket CreateUnsubscribePacket(MqttClientUnsubscribeOptions options)
        {
            if (options == null) throw new ArgumentNullException(nameof(options));
@@ -215,6 +272,18 @@ namespace MQTTnet.Formatter.V5
            return packet;
        }

+        public MqttUnsubAckPacket CreateUnsubAckPacket(MqttUnsubscribePacket unsubscribePacket, List<MqttUnsubscribeReasonCode> reasonCodes)
+        {
+            if (unsubscribePacket == null) throw new ArgumentNullException(nameof(unsubscribePacket));
+            if (reasonCodes == null) throw new ArgumentNullException(nameof(reasonCodes));
+
+            return new MqttUnsubAckPacket
+            {
+                PacketIdentifier = unsubscribePacket.PacketIdentifier,
+                ReasonCodes = reasonCodes
+            };
+        }
+
        public MqttDisconnectPacket CreateDisconnectPacket(MqttClientDisconnectOptions options)
        {
            var packet = new MqttDisconnectPacket();
@@ -231,7 +300,7 @@ namespace MQTTnet.Formatter.V5
            return packet;
        }

-        public MqttClientPublishResult CreatePublishResult(MqttPubAckPacket pubAckPacket)
+        public MqttClientPublishResult CreateClientPublishResult(MqttPubAckPacket pubAckPacket)
        {
            var result = new MqttClientPublishResult
            {
@@ -244,7 +313,7 @@ namespace MQTTnet.Formatter.V5
            {
                // QoS 0 has no response. So we treat it as a success always.
                // Both enums have the same values. So it can be easily converted.
-                result.ReasonCode = (MqttClientPublishReasonCode)pubAckPacket.ReasonCode;
+                result.ReasonCode = (MqttClientPublishReasonCode)(int)(pubAckPacket.ReasonCode ?? 0);

                result.PacketIdentifier = pubAckPacket.PacketIdentifier;
            }
@@ -252,7 +321,7 @@ namespace MQTTnet.Formatter.V5
            return result;
        }

-        public MqttClientPublishResult CreatePublishResult(MqttPubRecPacket pubRecPacket, MqttPubCompPacket pubCompPacket)
+        public MqttClientPublishResult CreateClientPublishResult(MqttPubRecPacket pubRecPacket, MqttPubCompPacket pubCompPacket)
        {
            if (pubRecPacket == null || pubCompPacket == null)
            {
@@ -285,10 +354,10 @@ namespace MQTTnet.Formatter.V5
            if (pubRecPacket.ReasonCode.HasValue)
            {
                // Both enums share the same values.
-                result.ReasonCode = (MqttClientPublishReasonCode)pubRecPacket.ReasonCode.Value;
+                result.ReasonCode = (MqttClientPublishReasonCode)(pubRecPacket.ReasonCode ?? 0);
            }

            return result;
        }
    }
-}
+}
@@ -25,21 +25,21 @@ namespace MQTTnet.Formatter.V5

            switch ((MqttControlPacketType)controlPacketType)
            {
-                case MqttControlPacketType.Connect: return DecodeConnectPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.ConnAck: return DecodeConnAckPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.Disconnect: return DecodeDisconnectPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.Publish: return DecodePublishPacket(receivedMqttPacket.FixedHeader, receivedMqttPacket.Body);
-                case MqttControlPacketType.PubAck: return DecodePubAckPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.PubRec: return DecodePubRecPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.PubRel: return DecodePubRelPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.PubComp: return DecodePubCompPacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.Connect: return DecodeConnectPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.ConnAck: return DecodeConnAckPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.Disconnect: return DecodeDisconnectPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.Publish: return DecodePublishPacket(receivedMqttPacket.FixedHeader, receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.PubAck: return DecodePubAckPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.PubRec: return DecodePubRecPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.PubRel: return DecodePubRelPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.PubComp: return DecodePubCompPacket(receivedMqttPacket.BodyReader);
                case MqttControlPacketType.PingReq: return DecodePingReqPacket();
                case MqttControlPacketType.PingResp: return DecodePingRespPacket();
-                case MqttControlPacketType.Subscribe: return DecodeSubscribePacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.SubAck: return DecodeSubAckPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.Unsubscibe: return DecodeUnsubscribePacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.UnsubAck: return DecodeUnsubAckPacket(receivedMqttPacket.Body);
-                case MqttControlPacketType.Auth: return DecodeAuthPacket(receivedMqttPacket.Body);
+                case MqttControlPacketType.Subscribe: return DecodeSubscribePacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.SubAck: return DecodeSubAckPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.Unsubscibe: return DecodeUnsubscribePacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.UnsubAck: return DecodeUnsubAckPacket(receivedMqttPacket.BodyReader);
+                case MqttControlPacketType.Auth: return DecodeAuthPacket(receivedMqttPacket.BodyReader);

                default: throw new MqttProtocolViolationException($"Packet type ({controlPacketType}) not supported.");
            }
@@ -254,6 +254,10 @@ namespace MQTTnet.Formatter.V5
                {
                    packet.Properties.ReceiveMaximum = propertiesReader.ReadReceiveMaximum();
                }
+                else if (propertiesReader.CurrentPropertyId == MqttPropertyId.MaximumQoS)
+                {
+                    packet.Properties.MaximumQoS = propertiesReader.ReadMaximumQoS();
+                }
                else if (propertiesReader.CurrentPropertyId == MqttPropertyId.AssignedClientIdentifier)
                {
                    packet.Properties.AssignedClientIdentifier = propertiesReader.ReadAssignedClientIdentifier();
@@ -6,22 +6,15 @@ using MQTTnet.Protocol;

 namespace MQTTnet.Formatter.V5
 {
-    public class MqttV500PacketEncoder
+    public sealed class MqttV500PacketEncoder
    {
-        private readonly IMqttPacketWriter _packetWriter;
-
-        public MqttV500PacketEncoder()
-            : this(new MqttPacketWriter())
-        {
-
-        }
+        readonly IMqttPacketWriter _packetWriter;

        public MqttV500PacketEncoder(IMqttPacketWriter packetWriter)
        {
-            _packetWriter = packetWriter;
+            _packetWriter = packetWriter ?? throw new ArgumentNullException(nameof(packetWriter));
        }

-
        public ArraySegment<byte> Encode(MqttBasePacket packet)
        {
            if (packet == null) throw new ArgumentNullException(nameof(packet));
@@ -52,7 +45,7 @@ namespace MQTTnet.Formatter.V5
            _packetWriter.FreeBuffer();
        }

-        private static byte EncodePacket(MqttBasePacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePacket(MqttBasePacket packet, IMqttPacketWriter packetWriter)
        {
            switch (packet)
            {
@@ -76,7 +69,7 @@ namespace MQTTnet.Formatter.V5
            }
        }

-        private static byte EncodeConnectPacket(MqttConnectPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeConnectPacket(MqttConnectPacket packet, IMqttPacketWriter packetWriter)
        {
            if (packet == null) throw new ArgumentNullException(nameof(packet));
            if (packetWriter == null) throw new ArgumentNullException(nameof(packetWriter));
@@ -176,7 +169,7 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Connect);
        }

-        private static byte EncodeConnAckPacket(MqttConnAckPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeConnAckPacket(MqttConnAckPacket packet, IMqttPacketWriter packetWriter)
        {
            if (packet == null) throw new ArgumentNullException(nameof(packet));
            if (packetWriter == null) throw new ArgumentNullException(nameof(packetWriter));
@@ -203,6 +196,7 @@ namespace MQTTnet.Formatter.V5
                propertiesWriter.WriteAuthenticationData(packet.Properties.AuthenticationData);
                propertiesWriter.WriteRetainAvailable(packet.Properties.RetainAvailable);
                propertiesWriter.WriteReceiveMaximum(packet.Properties.ReceiveMaximum);
+                propertiesWriter.WriteMaximumQoS(packet.Properties.MaximumQoS);
                propertiesWriter.WriteAssignedClientIdentifier(packet.Properties.AssignedClientIdentifier);
                propertiesWriter.WriteTopicAliasMaximum(packet.Properties.TopicAliasMaximum);
                propertiesWriter.WriteReasonString(packet.Properties.ReasonString);
@@ -221,7 +215,7 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.ConnAck);
        }

-        private static byte EncodePublishPacket(MqttPublishPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePublishPacket(MqttPublishPacket packet, IMqttPacketWriter packetWriter)
        {
            if (packet == null) throw new ArgumentNullException(nameof(packet));
            if (packetWriter == null) throw new ArgumentNullException(nameof(packetWriter));
@@ -235,12 +229,12 @@ namespace MQTTnet.Formatter.V5

            if (packet.QualityOfServiceLevel > MqttQualityOfServiceLevel.AtMostOnce)
            {
-                if (!packet.PacketIdentifier.HasValue)
+                if (packet.PacketIdentifier == 0)
                {
                    throw new MqttProtocolViolationException("Publish packet has no packet identifier.");
                }

-                packetWriter.Write(packet.PacketIdentifier.Value);
+                packetWriter.Write(packet.PacketIdentifier);
            }
            else
            {
@@ -253,13 +247,18 @@ namespace MQTTnet.Formatter.V5
            var propertiesWriter = new MqttV500PropertiesWriter();
            if (packet.Properties != null)
            {
-                propertiesWriter.WritePayloadFormatIndicator(packet.Properties.PayloadFormatIndicator);
-                propertiesWriter.WriteMessageExpiryInterval(packet.Properties.MessageExpiryInterval);
-                propertiesWriter.WriteTopicAlias(packet.Properties.TopicAlias);
-                propertiesWriter.WriteResponseTopic(packet.Properties.ResponseTopic);
-                propertiesWriter.WriteCorrelationData(packet.Properties.CorrelationData);
-                propertiesWriter.WriteSubscriptionIdentifiers(packet.Properties.SubscriptionIdentifiers);
+                if (packet.Properties.TopicAlias == 0)
+                {
+                    throw new MqttProtocolViolationException("A Topic Alias of 0 is not permitted. A sender MUST NOT send a PUBLISH packet containing a Topic Alias which has the value 0 [MQTT-3.3.2-8].");
+                }
+
                propertiesWriter.WriteContentType(packet.Properties.ContentType);
+                propertiesWriter.WriteCorrelationData(packet.Properties.CorrelationData);
+                propertiesWriter.WriteMessageExpiryInterval(packet.Properties.MessageExpiryInterval);
+                propertiesWriter.WritePayloadFormatIndicator(packet.Properties.PayloadFormatIndicator);
+                propertiesWriter.WriteResponseTopic(packet.Properties.ResponseTopic);
+                propertiesWriter.WriteSubscriptionIdentifiers(packet.Properties.SubscriptionIdentifiers);
+                propertiesWriter.WriteTopicAlias(packet.Properties.TopicAlias);
                propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
            }

@@ -287,12 +286,12 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Publish, fixedHeader);
        }

-        private static byte EncodePubAckPacket(MqttPubAckPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePubAckPacket(MqttPubAckPacket packet, IMqttPacketWriter packetWriter)
        {
            if (packet == null) throw new ArgumentNullException(nameof(packet));
            if (packetWriter == null) throw new ArgumentNullException(nameof(packetWriter));

-            if (!packet.PacketIdentifier.HasValue)
+            if (packet.PacketIdentifier == 0)
            {
                throw new MqttProtocolViolationException("PubAck packet has no packet identifier.");
            }
@@ -302,7 +301,7 @@ namespace MQTTnet.Formatter.V5
                throw new MqttProtocolViolationException("PubAck packet must contain a reason code.");
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);
            
            var propertiesWriter = new MqttV500PropertiesWriter();
            if (packet.Properties != null)
@@ -320,9 +319,9 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubAck);
        }

-        private static byte EncodePubRecPacket(MqttPubRecPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePubRecPacket(MqttPubRecPacket packet, IMqttPacketWriter packetWriter)
        {
-            ThrowIfPacketIdentifierIsInvalid(packet);
+            ThrowIfPacketIdentifierIsInvalid(packet.PacketIdentifier, packet);

            if (!packet.ReasonCode.HasValue)
            {
@@ -336,7 +335,7 @@ namespace MQTTnet.Formatter.V5
                propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            if (packetWriter.Length > 0 || packet.ReasonCode.Value != MqttPubRecReasonCode.Success)
            {
@@ -347,9 +346,9 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubRec);
        }

-        private static byte EncodePubRelPacket(MqttPubRelPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePubRelPacket(MqttPubRelPacket packet, IMqttPacketWriter packetWriter)
        {
-            ThrowIfPacketIdentifierIsInvalid(packet);
+            ThrowIfPacketIdentifierIsInvalid(packet.PacketIdentifier, packet);

            if (!packet.ReasonCode.HasValue)
            {
@@ -363,7 +362,7 @@ namespace MQTTnet.Formatter.V5
                propertiesWriter.WriteUserProperties(packet.Properties.UserProperties);
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);
            
            if (propertiesWriter.Length > 0 || packet.ReasonCode.Value != MqttPubRelReasonCode.Success)
            {
@@ -374,16 +373,16 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubRel, 0x02);
        }

-        private static byte EncodePubCompPacket(MqttPubCompPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodePubCompPacket(MqttPubCompPacket packet, IMqttPacketWriter packetWriter)
        {
-            ThrowIfPacketIdentifierIsInvalid(packet);
+            ThrowIfPacketIdentifierIsInvalid(packet.PacketIdentifier, packet);

            if (!packet.ReasonCode.HasValue)
            {
                ThrowReasonCodeNotSetException();
            }

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);
            
            var propertiesWriter = new MqttV500PropertiesWriter();
            if (packet.Properties != null)
@@ -401,13 +400,13 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PubComp);
        }

-        private static byte EncodeSubscribePacket(MqttSubscribePacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeSubscribePacket(MqttSubscribePacket packet, IMqttPacketWriter packetWriter)
        {
            if (packet.TopicFilters?.Any() != true) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.8.3-3].");

-            ThrowIfPacketIdentifierIsInvalid(packet);
+            ThrowIfPacketIdentifierIsInvalid(packet.PacketIdentifier, packet);

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            var propertiesWriter = new MqttV500PropertiesWriter();
            if (packet.Properties != null)
@@ -448,13 +447,13 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Subscribe, 0x02);
        }

-        private static byte EncodeSubAckPacket(MqttSubAckPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeSubAckPacket(MqttSubAckPacket packet, IMqttPacketWriter packetWriter)
        {
            if (packet.ReasonCodes?.Any() != true) throw new MqttProtocolViolationException("At least one reason code must be set[MQTT - 3.8.3 - 3].");

-            ThrowIfPacketIdentifierIsInvalid(packet);
+            ThrowIfPacketIdentifierIsInvalid(packet.PacketIdentifier, packet);

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            var propertiesWriter = new MqttV500PropertiesWriter();
            if (packet.Properties != null)
@@ -473,13 +472,13 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.SubAck);
        }

-        private static byte EncodeUnsubscribePacket(MqttUnsubscribePacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeUnsubscribePacket(MqttUnsubscribePacket packet, IMqttPacketWriter packetWriter)
        {
            if (packet.TopicFilters?.Any() != true) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.10.3-2].");

-            ThrowIfPacketIdentifierIsInvalid(packet);
+            ThrowIfPacketIdentifierIsInvalid(packet.PacketIdentifier, packet);

-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            var propertiesWriter = new MqttV500PropertiesWriter();
            if (packet.Properties != null)
@@ -497,13 +496,13 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Unsubscibe, 0x02);
        }

-        private static byte EncodeUnsubAckPacket(MqttUnsubAckPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeUnsubAckPacket(MqttUnsubAckPacket packet, IMqttPacketWriter packetWriter)
        {
            if (packet.ReasonCodes?.Any() != true) throw new MqttProtocolViolationException("At least one reason code must be set[MQTT - 3.8.3 - 3].");

-            ThrowIfPacketIdentifierIsInvalid(packet);
+            ThrowIfPacketIdentifierIsInvalid(packet.PacketIdentifier, packet);
            
-            packetWriter.Write(packet.PacketIdentifier.Value);
+            packetWriter.Write(packet.PacketIdentifier);

            var propertiesWriter = new MqttV500PropertiesWriter();
            if (packet.Properties != null)
@@ -522,7 +521,7 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.UnsubAck);
        }

-        private static byte EncodeDisconnectPacket(MqttDisconnectPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeDisconnectPacket(MqttDisconnectPacket packet, IMqttPacketWriter packetWriter)
        {
            if (!packet.ReasonCode.HasValue)
            {
@@ -545,17 +544,17 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Disconnect);
        }

-        private static byte EncodePingReqPacket()
+        static byte EncodePingReqPacket()
        {
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PingReq);
        }

-        private static byte EncodePingRespPacket()
+        static byte EncodePingRespPacket()
        {
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.PingResp);
        }

-        private static byte EncodeAuthPacket(MqttAuthPacket packet, IMqttPacketWriter packetWriter)
+        static byte EncodeAuthPacket(MqttAuthPacket packet, IMqttPacketWriter packetWriter)
        {
            packetWriter.Write((byte)packet.ReasonCode);

@@ -573,14 +572,16 @@ namespace MQTTnet.Formatter.V5
            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Auth);
        }

-        private static void ThrowReasonCodeNotSetException()
+        static void ThrowReasonCodeNotSetException()
        {
            throw new MqttProtocolViolationException("The ReasonCode must be set for MQTT version 5.");
        }

-        private static void ThrowIfPacketIdentifierIsInvalid(IMqttPacketWithIdentifier packet)
+        static void ThrowIfPacketIdentifierIsInvalid(ushort packetIdentifier, MqttBasePacket packet)
        {
-            if (!packet.PacketIdentifier.HasValue)
+            // SUBSCRIBE, UNSUBSCRIBE, and PUBLISH(in cases where QoS > 0) Control Packets MUST contain a non-zero 16 - bit Packet Identifier[MQTT - 2.3.1 - 1]. 
+
+            if (packetIdentifier == 0)
            {
                throw new MqttProtocolViolationException($"Packet identifier is not set for {packet.GetType().Name}.");
            }
@@ -4,15 +4,10 @@ using MQTTnet.Packets;

 namespace MQTTnet.Formatter.V5
 {
-    public class MqttV500PacketFormatter : IMqttPacketFormatter
+    public sealed class MqttV500PacketFormatter : IMqttPacketFormatter
    {
-        private readonly MqttV500PacketEncoder _encoder;
-        private readonly MqttV500PacketDecoder _decoder = new MqttV500PacketDecoder();
-
-        public MqttV500PacketFormatter()
-        {
-            _encoder = new MqttV500PacketEncoder();
-        }
+        readonly MqttV500PacketDecoder _decoder = new MqttV500PacketDecoder();
+        readonly MqttV500PacketEncoder _encoder;

        public MqttV500PacketFormatter(IMqttPacketWriter writer)
        {
@@ -82,6 +82,17 @@ namespace MQTTnet.Formatter.V5
            return _body.ReadTwoByteInteger();
        }

+        public MqttQualityOfServiceLevel ReadMaximumQoS()
+        {
+            byte value = _body.ReadByte();
+            if (value > 1)
+            {
+                throw new MqttProtocolViolationException($"Unexpected Maximum QoS value: {value}");
+            }
+            
+            return (MqttQualityOfServiceLevel)value;
+        }
+
        public string ReadAssignedClientIdentifier()
        {
            return _body.ReadStringWithLengthPrefix();
@@ -5,10 +5,9 @@ using MQTTnet.Protocol;

 namespace MQTTnet.Formatter.V5
 {
-    public class MqttV500PropertiesWriter
+    public sealed class MqttV500PropertiesWriter
    {
-        // TODO: Consider lazy init on first write to avoid useless allocations.
-        private readonly MqttPacketWriter _packetWriter = new MqttPacketWriter();
+        readonly MqttPacketWriter _packetWriter = new MqttPacketWriter();

        public int Length => _packetWriter.Length;

@@ -133,6 +132,17 @@ namespace MQTTnet.Formatter.V5
            Write(MqttPropertyId.ReceiveMaximum, value);
        }

+        public void WriteMaximumQoS(MqttQualityOfServiceLevel? value)
+        {
+            if (!value.HasValue || value.Value > MqttQualityOfServiceLevel.AtLeastOnce)
+            {
+                return;
+            }
+
+            _packetWriter.Write((byte)MqttPropertyId.MaximumQoS);
+            _packetWriter.Write((byte)value.Value);
+        }
+
        public void WriteMaximumPacketSize(uint? value)
        {
            WriteAsFourByteInteger(MqttPropertyId.MaximumPacketSize, value);
@@ -178,7 +188,7 @@ namespace MQTTnet.Formatter.V5
            Write(MqttPropertyId.ResponseInformation, value);
        }

-        private void Write(MqttPropertyId id, bool? value)
+        void Write(MqttPropertyId id, bool? value)
        {
            if (!value.HasValue)
            {
@@ -189,7 +199,7 @@ namespace MQTTnet.Formatter.V5
            _packetWriter.Write(value.Value ? (byte)0x1 : (byte)0x0);
        }

-        private void Write(MqttPropertyId id, byte? value)
+        void Write(MqttPropertyId id, byte? value)
        {
            if (!value.HasValue)
            {
@@ -200,7 +210,7 @@ namespace MQTTnet.Formatter.V5
            _packetWriter.Write(value.Value);
        }

-        private void Write(MqttPropertyId id, ushort? value)
+        void Write(MqttPropertyId id, ushort? value)
        {
            if (!value.HasValue)
            {
@@ -211,7 +221,7 @@ namespace MQTTnet.Formatter.V5
            _packetWriter.Write(value.Value);
        }

-        private void WriteAsVariableLengthInteger(MqttPropertyId id, uint? value)
+        void WriteAsVariableLengthInteger(MqttPropertyId id, uint? value)
        {
            if (!value.HasValue)
            {
@@ -222,7 +232,7 @@ namespace MQTTnet.Formatter.V5
            _packetWriter.WriteVariableLengthInteger(value.Value);
        }

-        private void WriteAsFourByteInteger(MqttPropertyId id, uint? value)
+        void WriteAsFourByteInteger(MqttPropertyId id, uint? value)
        {
            if (!value.HasValue)
            {
@@ -236,7 +246,7 @@ namespace MQTTnet.Formatter.V5
            _packetWriter.Write((byte)value.Value);
        }

-        private void Write(MqttPropertyId id, string value)
+        void Write(MqttPropertyId id, string value)
        {
            if (value == null)
            {
@@ -247,7 +257,7 @@ namespace MQTTnet.Formatter.V5
            _packetWriter.WriteWithLengthPrefix(value);
        }

-        private void Write(MqttPropertyId id, byte[] value)
+        void Write(MqttPropertyId id, byte[] value)
        {
            if (value == null)
            {
@@ -4,6 +4,10 @@ namespace MQTTnet
 {
    public interface IApplicationMessageReceiver
    {
+        /// <summary>
+        /// Gets or sets the application message received handler that is fired every time a new message is received on the client's subscriptions.
+        /// Hint: Initialize handlers before you connect the client to avoid issues.
+        /// </summary>
        IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler { get; set; }
    }
 }
@@ -4,6 +4,7 @@ using System.Net;
 using System.Net.Sockets;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Exceptions;

 namespace MQTTnet.Implementations
 {
@@ -33,6 +34,9 @@ namespace MQTTnet.Implementations

        public bool NoDelay
        {
+            // We cannot use the _NoDelay_ property from the socket because there is an issue in .NET 4.5.2, 4.6.
+            // The decompiled code is: this.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.Debug, value ? 1 : 0);
+            // Which is wrong because the "NoDelay" should be set and not "Debug".
            get => (int)_socket.GetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay) > 0;
            set => _socket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, value ? 1 : 0);
        }
@@ -48,13 +52,19 @@ namespace MQTTnet.Implementations
            get => _socket.ReceiveBufferSize;
            set => _socket.ReceiveBufferSize = value;
        }
-
+        
        public int SendBufferSize
        {
            get => _socket.SendBufferSize;
            set => _socket.SendBufferSize = value;
        }

+        public int SendTimeout
+        {
+            get => _socket.SendTimeout;
+            set => _socket.SendTimeout = value;
+        }
+
        public EndPoint RemoteEndPoint => _socket.RemoteEndPoint;

        public bool ReuseAddress
@@ -69,11 +79,10 @@ namespace MQTTnet.Implementations
            {
 #if NET452 || NET461
                var clientSocket = await Task.Factory.FromAsync(_socket.BeginAccept, _socket.EndAccept, null).ConfigureAwait(false);
-                return new CrossPlatformSocket(clientSocket);
 #else
                var clientSocket = await _socket.AcceptAsync().ConfigureAwait(false);
-                return new CrossPlatformSocket(clientSocket);
 #endif
+                return new CrossPlatformSocket(clientSocket);
            }
            catch (ObjectDisposedException)
            {
@@ -115,9 +124,19 @@ namespace MQTTnet.Implementations
                    _networkStream = new NetworkStream(_socket, true);
                }
            }
+            catch (SocketException socketException)
+            {
+                if (socketException.SocketErrorCode == SocketError.OperationAborted)
+                {
+                    throw new OperationCanceledException();
+                }
+
+                throw new MqttCommunicationException($"Error while connecting with host '{host}:{port}'.", socketException);
+            }
            catch (ObjectDisposedException)
            {
                // This will happen when _socket.EndConnect gets called by Task library but the socket is already disposed.
+                cancellationToken.ThrowIfCancellationRequested();
            }
        }

@@ -3,6 +3,7 @@ using MQTTnet.Client.Options;
 using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
 using System;
+using MQTTnet.Channel;

 namespace MQTTnet.Implementations
 {
@@ -19,16 +20,19 @@ namespace MQTTnet.Implementations
        {
            if (options == null) throw new ArgumentNullException(nameof(options));

+            IMqttChannel channel;
            switch (options.ChannelOptions)
            {
                case MqttClientTcpOptions _:
                    {
-                        return new MqttChannelAdapter(new MqttTcpChannel(options), new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttPacketWriter()), _logger);
+                        channel = new MqttTcpChannel(options);
+                        break;
                    }

                case MqttClientWebSocketOptions webSocketOptions:
                    {
-                        return new MqttChannelAdapter(new MqttWebSocketChannel(webSocketOptions), new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttPacketWriter()), _logger);
+                        channel = new MqttWebSocketChannel(webSocketOptions);
+                        break;
                    }

                default:
@@ -36,6 +40,9 @@ namespace MQTTnet.Implementations
                        throw new NotSupportedException();
                    }
            }
+
+            var packetFormatterAdapter = new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttPacketWriter());
+            return new MqttChannelAdapter(channel, packetFormatterAdapter, options.PacketInspector, _logger);
        }
    }
 }
@@ -75,11 +75,23 @@ namespace MQTTnet.Implementations
                    _socket.Control.IgnorableServerCertificateErrors.Add(ignorableChainValidationResult);
                }

+#if NETCOREAPP3_1 || NET5_0
+                var socketProtectionLevel = SocketProtectionLevel.Tls13;
+                if (_options.TlsOptions.SslProtocol == SslProtocols.Tls12)
+                {
+                    socketProtectionLevel = SocketProtectionLevel.Tls12;
+                }
+                else if (_options.TlsOptions.SslProtocol == SslProtocols.Tls11)
+                {
+                    socketProtectionLevel = SocketProtectionLevel.Tls11;
+                }
+#else
                var socketProtectionLevel = SocketProtectionLevel.Tls12;
                if (_options.TlsOptions.SslProtocol == SslProtocols.Tls11)
                {
                    socketProtectionLevel = SocketProtectionLevel.Tls11;
                }
+#endif
                else if (_options.TlsOptions.SslProtocol == SslProtocols.Tls)
                {
                    socketProtectionLevel = SocketProtectionLevel.Tls10;
@@ -129,7 +141,7 @@ namespace MQTTnet.Implementations

            if (options.TlsOptions.Certificates.Count > 1)
            {
-                throw new NotSupportedException("Only one client certificate is supported for UWP.");
+                throw new NotSupportedException("Only one client certificate is supported when using 'uap10.0'.");
            }

            return new Certificate(options.TlsOptions.Certificates.First().AsBuffer());
@@ -10,20 +10,21 @@ using System.Runtime.ExceptionServices;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Exceptions;

 namespace MQTTnet.Implementations
 {
    public sealed class MqttTcpChannel : IMqttChannel
    {
        readonly IMqttClientOptions _clientOptions;
-        readonly MqttClientTcpOptions _options;
+        readonly MqttClientTcpOptions _tcpOptions;

        Stream _stream;

        public MqttTcpChannel(IMqttClientOptions clientOptions)
        {
            _clientOptions = clientOptions ?? throw new ArgumentNullException(nameof(clientOptions));
-            _options = (MqttClientTcpOptions)clientOptions.ChannelOptions;
+            _tcpOptions = (MqttClientTcpOptions)clientOptions.ChannelOptions;

            IsSecureConnection = clientOptions.ChannelOptions?.TlsOptions?.UseTls == true;
        }
@@ -49,34 +50,35 @@ namespace MQTTnet.Implementations
            CrossPlatformSocket socket = null;
            try
            {
-                if (_options.AddressFamily == AddressFamily.Unspecified)
+                if (_tcpOptions.AddressFamily == AddressFamily.Unspecified)
                {
                    socket = new CrossPlatformSocket();
                }
                else
                {
-                    socket = new CrossPlatformSocket(_options.AddressFamily);
+                    socket = new CrossPlatformSocket(_tcpOptions.AddressFamily);
                }

-                socket.ReceiveBufferSize = _options.BufferSize;
-                socket.SendBufferSize = _options.BufferSize;
-                socket.NoDelay = _options.NoDelay;
+                socket.ReceiveBufferSize = _tcpOptions.BufferSize;
+                socket.SendBufferSize = _tcpOptions.BufferSize;
+                socket.SendTimeout = (int)_clientOptions.CommunicationTimeout.TotalMilliseconds;
+                socket.NoDelay = _tcpOptions.NoDelay;

-                if (_options.DualMode.HasValue)
+                if (_tcpOptions.DualMode.HasValue)
                {
                    // It is important to avoid setting the flag if no specific value is set by the user
                    // because on IPv4 only networks the setter will always throw an exception. Regardless
                    // of the actual value.
-                    socket.DualMode = _options.DualMode.Value;
+                    socket.DualMode = _tcpOptions.DualMode.Value;
                }

-                await socket.ConnectAsync(_options.Server, _options.GetPort(), cancellationToken).ConfigureAwait(false);
+                await socket.ConnectAsync(_tcpOptions.Server, _tcpOptions.GetPort(), cancellationToken).ConfigureAwait(false);

                cancellationToken.ThrowIfCancellationRequested();

                var networkStream = socket.GetStream();

-                if (_options.TlsOptions?.UseTls == true)
+                if (_tcpOptions.TlsOptions?.UseTls == true)
                {
                    var sslStream = new SslStream(networkStream, false, InternalUserCertificateValidationCallback);
                    try
@@ -84,16 +86,16 @@ namespace MQTTnet.Implementations
 #if NETCOREAPP3_1
                        var sslOptions = new SslClientAuthenticationOptions
                        {
-                            ApplicationProtocols = _options.TlsOptions.ApplicationProtocols,
+                            ApplicationProtocols = _tcpOptions.TlsOptions.ApplicationProtocols,
                            ClientCertificates = LoadCertificates(),
-                            EnabledSslProtocols = _options.TlsOptions.SslProtocol,
-                            CertificateRevocationCheckMode = _options.TlsOptions.IgnoreCertificateRevocationErrors ? X509RevocationMode.Online : X509RevocationMode.NoCheck,
-                            TargetHost = _options.Server
+                            EnabledSslProtocols = _tcpOptions.TlsOptions.SslProtocol,
+                            CertificateRevocationCheckMode = _tcpOptions.TlsOptions.IgnoreCertificateRevocationErrors ? X509RevocationMode.NoCheck : X509RevocationMode.Online,
+                            TargetHost = _tcpOptions.Server
                        };

                        await sslStream.AuthenticateAsClientAsync(sslOptions, cancellationToken).ConfigureAwait(false);
-#else 
-                        await sslStream.AuthenticateAsClientAsync(_options.Server, LoadCertificates(), _options.TlsOptions.SslProtocol, !_options.TlsOptions.IgnoreCertificateRevocationErrors).ConfigureAwait(false);
+#else
+                        await sslStream.AuthenticateAsClientAsync(_tcpOptions.Server, LoadCertificates(), _tcpOptions.TlsOptions.SslProtocol, !_tcpOptions.TlsOptions.IgnoreCertificateRevocationErrors).ConfigureAwait(false);
 #endif
                    }
                    catch
@@ -131,22 +133,25 @@ namespace MQTTnet.Implementations

        public async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
        {
-            if (buffer is null) throw new ArgumentNullException(nameof(buffer));
-
            cancellationToken.ThrowIfCancellationRequested();

            try
            {
+                var stream = _stream;
+
+                if (stream == null)
+                {
+                    return 0;
+                }
+
+                if (!stream.CanRead)
+                {
+                    return 0;
+                }
+
                // Workaround for: https://github.com/dotnet/corefx/issues/24430
                using (cancellationToken.Register(Dispose))
                {
-                    var stream = _stream;
-
-                    if (stream == null)
-                    {
-                        throw new ObjectDisposedException(nameof(stream));
-                    }
-
                    return await stream.ReadAsync(buffer, offset, count, cancellationToken).ConfigureAwait(false);
                }
            }
@@ -168,8 +173,6 @@ namespace MQTTnet.Implementations

        public async Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
        {
-            if (buffer is null) throw new ArgumentNullException(nameof(buffer));
-
            cancellationToken.ThrowIfCancellationRequested();

            try
@@ -181,7 +184,7 @@ namespace MQTTnet.Implementations

                    if (stream == null)
                    {
-                        throw new ObjectDisposedException(nameof(stream));
+                        throw new MqttCommunicationException("The TCP connection is closed.");
                    }

                    await stream.WriteAsync(buffer, offset, count, cancellationToken).ConfigureAwait(false);
@@ -189,6 +192,7 @@ namespace MQTTnet.Implementations
            }
            catch (ObjectDisposedException)
            {
+                throw new MqttCommunicationException("The TCP connection is closed.");
            }
            catch (IOException exception)
            {
@@ -225,7 +229,7 @@ namespace MQTTnet.Implementations
            #region OBSOLETE

 #pragma warning disable CS0618 // Type or member is obsolete
-            var certificateValidationCallback = _options?.TlsOptions?.CertificateValidationCallback;
+            var certificateValidationCallback = _tcpOptions?.TlsOptions?.CertificateValidationCallback;
 #pragma warning restore CS0618 // Type or member is obsolete
            if (certificateValidationCallback != null)
            {
@@ -233,7 +237,7 @@ namespace MQTTnet.Implementations
            }
            #endregion

-            var certificateValidationHandler = _options?.TlsOptions?.CertificateValidationHandler;
+            var certificateValidationHandler = _tcpOptions?.TlsOptions?.CertificateValidationHandler;
            if (certificateValidationHandler != null)
            {
                var context = new MqttClientCertificateValidationCallbackContext
@@ -241,7 +245,7 @@ namespace MQTTnet.Implementations
                    Certificate = x509Certificate,
                    Chain = chain,
                    SslPolicyErrors = sslPolicyErrors,
-                    ClientOptions = _options
+                    ClientOptions = _tcpOptions
                };

                return certificateValidationHandler(context);
@@ -254,7 +258,7 @@ namespace MQTTnet.Implementations

            if (chain.ChainStatus.Any(c => c.Status == X509ChainStatusFlags.RevocationStatusUnknown || c.Status == X509ChainStatusFlags.Revoked || c.Status == X509ChainStatusFlags.OfflineRevocation))
            {
-                if (_options?.TlsOptions?.IgnoreCertificateRevocationErrors != true)
+                if (_tcpOptions?.TlsOptions?.IgnoreCertificateRevocationErrors != true)
                {
                    return false;
                }
@@ -262,24 +266,24 @@ namespace MQTTnet.Implementations

            if (chain.ChainStatus.Any(c => c.Status == X509ChainStatusFlags.PartialChain))
            {
-                if (_options?.TlsOptions?.IgnoreCertificateChainErrors != true)
+                if (_tcpOptions?.TlsOptions?.IgnoreCertificateChainErrors != true)
                {
                    return false;
                }
            }

-            return _options?.TlsOptions?.AllowUntrustedCertificates == true;
+            return _tcpOptions?.TlsOptions?.AllowUntrustedCertificates == true;
        }

        X509CertificateCollection LoadCertificates()
        {
            var certificates = new X509CertificateCollection();
-            if (_options.TlsOptions.Certificates == null)
+            if (_tcpOptions.TlsOptions.Certificates == null)
            {
                return certificates;
            }

-            foreach (var certificate in _options.TlsOptions.Certificates)
+            foreach (var certificate in _tcpOptions.TlsOptions.Certificates)
            {
                certificates.Add(certificate);
            }
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Christian	12f346115f	Improve RPC client handling.	2021-02-26 10:55:26 +01:00
Christian	05827341d4	Update codeql-analysis.yml	2021-02-23 12:05:24 +01:00
Christian	1e88d6a05b	Merge remote-tracking branch 'origin/master'	2021-02-23 11:46:38 +01:00
Christian	8261ba9dc1	Update docs.	2021-02-23 11:46:16 +01:00
Christian	b766c1bebb	Refactor keep alive message handling in order to fix issues with sudden disconnects.	2021-02-23 11:45:22 +01:00
Christian	6c188899fb	Create codeql-analysis.yml	2021-02-21 11:33:51 +01:00
Christian	2d4ea8ee9b	Improve nuget packages.	2021-02-19 21:52:42 +01:00
Christian	15d3761843	Merge pull request #1097 from yyjdelete/nuspec Update nuspecs	2021-02-19 21:50:49 +01:00
Christian	ed520455d0	Use the data converter only when creating packets.	2021-02-19 21:45:23 +01:00
Christian	cfc4ebe6a3	Expose Dup flag in application messages (#1096 ).	2021-02-19 21:39:23 +01:00
Christian	120b7fb7d1	Fix RPC issue #1093 by calling both message handlers.	2021-02-18 18:56:15 +01:00
SilverFox	8b164a4846	Update nuspecs Manually sync with the file generated by `msbuild /t:pack` or `dotnet pack`, and remove some unnessary dependencies	2021-02-18 11:26:54 +08:00
Christian	fda4272611	Update docs.	2021-02-11 12:31:13 +01:00
Christian	88cc79d52f	Fix issues in nuspecs.	2021-02-11 12:25:58 +01:00
Christian	8ba960343c	Fix exception handling issues (#1082 ).	2021-02-08 13:29:15 +01:00
Christian	0976fa682a	Merge pull request #1083 from milbrandt/bugfix/noUsername Test for Regression: No exception on ConnectAsync(null, password) [MQTT-3.1.2-22]	2021-02-06 13:38:04 +01:00
Christian	18cc454842	Fix build script for .net5.0.	2021-02-06 13:36:23 +01:00
Volker Milbrandt	e342a51d50	Merge branch 'master'	2021-02-04 21:23:02 +01:00
Volker Milbrandt	57652c76cf	tests with MqttClient.ConnectAsync with credentials for all four combinations of null/non-null for username and password	2021-02-04 21:09:36 +01:00
HansM	bb52159e49	Added reference to SparkplugNet.	2021-01-31 17:35:39 +01:00
HansM	109acccd19	Update MQTTnet.nuspec Added code documentation hint.	2021-01-31 11:34:27 +01:00
HansM	deb2c3dec6	Merge pull request #1055 from chkr1011/add-code-doc Added client documentation.	2021-01-31 11:33:13 +01:00
HansM	63ca6086d5	Added missing changelog entry. Missing changelog change from https://github.com/chkr1011/MQTTnet/pull/1076.	2021-01-30 15:39:04 +01:00
Christian	3f92f2ca2b	Remove UWP test app because it gets replaced by MQTTnet.App in a separate repository.	2021-01-30 13:24:24 +01:00
Christian	a13874d8a5	Add missing overloads for client disconnect. Add timeout for disconnect in managed client.	2021-01-30 13:17:03 +01:00
Christian	c91a1f8572	Update solution settings.	2021-01-30 13:12:41 +01:00
Christian	b103718bd9	Add Unit Tests.	2021-01-29 23:17:16 +01:00
Christian	b88924bce5	Fixed wrong buffer size calculation.	2021-01-29 23:10:40 +01:00
Christian	f3f1d81b52	Update docs.	2021-01-29 22:44:18 +01:00
Christian	031b60878d	Merge pull request #1071 from muneebmajeed/master Allow to respond with a reason code in PUBACK/PUBREC	2021-01-29 22:27:09 +01:00
HansM	1fbf20a569	Merge pull request #1076 from dagophil/bug/topic-filter-comparer-edge-case The topic filter comparer now checks for e.g. "foo/" matching "foo/#".	2021-01-29 18:24:37 +01:00
Philip Schill	b1bf7698aa	The topic filter comparer now checks for e.g. "foo/" matching "foo/#".	2021-01-29 17:37:47 +01:00
Muneeb Majeed	f8eaf02516	Allow to respond with a reason code in PUBACK/PUBREC	2021-01-26 17:18:52 -05:00
Christian	df45540d6b	Update docs.	2021-01-25 22:28:01 +01:00
Christian	2abcf6d8bc	Update docs.	2021-01-25 22:27:45 +01:00
Christian	c1001db450	Add packet inspector API.	2021-01-24 20:58:15 +01:00
SeppPenner	3d8d06f9b3	Hopefully completely reset the IManagedMqttClient file.	2021-01-15 20:43:57 +01:00
SeppPenner	d804b805c1	Smaller changes on the comments.	2021-01-15 20:41:47 +01:00
SeppPenner	bba04e2b5d	Updated all code comments, should be ok now.	2021-01-15 20:34:33 +01:00
SeppPenner	5eab337e13	Removed not needed comments on client side (Server side is still missing).	2021-01-15 19:41:45 +01:00
Christian	e1d39a3fef	Fix build of MQTTnet Server.	2021-01-10 12:55:38 +01:00
Christian	3f5d627e9e	Fix issues in QoS 2 handling.	2021-01-07 23:22:45 +01:00
SeppPenner	2047f44554	Added client documentation.	2021-01-03 21:46:53 +01:00
Christian	75845d6416	Fix cancellation issues when connecting.	2021-01-01 15:56:38 +01:00
Christian	74e952bb03	Merge remote-tracking branch 'origin/master'	2020-12-23 21:38:14 +01:00
Christian	3773048bc5	Update docs.	2020-12-23 21:38:08 +01:00
Christian	f9aec0c067	Merge pull request #1048 from tobiasfrick/bugfix/cleandisconnect Only set _cleanDisconnectInitiated if no disconnect is pending	2020-12-23 17:21:04 +01:00
Tobias Frick	91c8a15f65	Only set _cleanDisconnectInitiated if no disconnect is pending	2020-12-21 13:26:59 +01:00
Christian	b95d6b08bc	Update docs.	2020-12-19 13:45:13 +01:00
Christian	a44ea74739	Merge pull request #1027 from StefanOssendorf/feature/Add-net5-tfm .Net5.0 TFMs added	2020-12-19 13:02:11 +01:00
JanEggers	02e65bca67	fixed .net 5 build	2020-12-16 14:45:15 +01:00
Stefan Ossendorf	37b783908a	.Net5.0 TFMs added .Net5.0 TFMs added and related nuget packages updated.	2020-12-16 14:45:15 +01:00
Christian	72211ae85a	Improve packet writer performance.	2020-12-14 21:17:22 +01:00
Christian	1f78a92c4d	Remove timeout from send method.	2020-12-14 21:17:11 +01:00
Christian	f92cfcd293	Add new multi threaded application message handler for server.	2020-12-13 11:36:31 +01:00
Christian	86256d1b10	Update README.md	2020-12-09 22:42:07 +01:00
Christian	c3e65390ab	Improve performance test.	2020-12-08 21:08:05 +01:00
Christian	b0699003e2	Refactor code.	2020-12-08 21:07:58 +01:00
Christian	1214b15260	Update docs.	2020-11-29 11:43:29 +01:00
Christian	322067466b	Fix wrong usage of client session items for undelivered messages.	2020-11-25 21:31:26 +01:00
Christian	ef2ed1c897	Remove _WithoutAutoReconnect_ from managed client.	2020-11-25 21:18:36 +01:00
Christian	9fddfb3e77	Add UnitTests	2020-11-25 21:08:01 +01:00
Christian	ec015e7620	Refactor naming for background tasks.	2020-11-25 21:07:50 +01:00
Christian	7738c5faa1	Refactor platform detection for unsupported features.	2020-11-21 15:43:32 +01:00
Christian	01bb09ff4b	Remove obsolete files.	2020-11-17 22:23:08 +01:00
Christian	e1494c1004	Update nuget packages.	2020-11-17 22:06:20 +01:00
Christian	1e2231c461	Improve Unit Tests.	2020-11-16 21:03:18 +01:00
Christian	de0f5dc1f0	Update docs.	2020-11-16 20:57:31 +01:00
Christian	a93f44217b	Align different formats of log messages.	2020-11-16 20:47:44 +01:00
Christian	f9c3014e52	Fix Unit Tests.	2020-11-15 14:34:59 +01:00
Christian	483c2d8b10	Fix Unit Tests.	2020-11-15 14:21:11 +01:00
Christian	02ab0e4903	Fix Unit Tests.	2020-11-15 14:17:18 +01:00
Christian	0bc25571e0	Fix Unit Tests	2020-11-15 12:46:10 +01:00
Christian Kratky	5b29b8cfd8	Fix Unit Tests.	2020-11-14 16:06:43 +01:00
Christian Kratky	dd9dc054e8	Merge remote-tracking branch 'origin/master'	2020-11-14 15:31:06 +01:00
Christian Kratky	b7c178b85c	Fix Unit Tests.	2020-11-14 15:30:57 +01:00
Christian	f8e29f8dc0	Update appveyor.yml	2020-11-14 15:24:49 +01:00
Christian	3d68951f68	Update MQTTnet.nuspec	2020-11-14 11:40:58 +01:00
Christian	7eb6d2d1e3	Merge pull request #1019 from chkr1011/feature/Single_Connection_Monitoring_Task Feature/single connection monitoring task	2020-11-14 10:36:18 +01:00
Christian Kratky	0446635ed6	Add comments.	2020-11-14 10:35:08 +01:00
Christian Kratky	4514348821	Fix Unit Tests.	2020-11-13 23:24:45 +01:00
Christian Kratky	7b32abe625	Fix Unit Tests.	2020-11-13 23:11:01 +01:00
Christian Kratky	0febc12b3d	Merge branch 'master' into feature/Single_Connection_Monitoring_Task	2020-11-13 20:36:51 +01:00
Christian Kratky	d0a848c8b4	Improve performance.	2020-11-13 20:33:47 +01:00
Christian	fe69f5a633	Merge pull request #1029 from mmuecke/patch-1 Added reference to Rx Wrapper for Managed Client	2020-11-12 11:26:22 +01:00
mmuecke	ca95754fc3	Added reference to Rx Wrapper for Managed Client	2020-11-12 00:24:01 +00:00
Christian Kratky	cc405c3e90	Update settings.	2020-11-11 21:12:37 +01:00
Christian Kratky	315206f05e	Update settings.	2020-11-11 21:12:15 +01:00
Christian Kratky	f252374437	Extend support for topic alias.	2020-11-11 21:12:04 +01:00
Christian Kratky	38d3531db6	Refactor code.	2020-11-11 21:11:49 +01:00
Christian Kratky	da5a172504	Refactor code.	2020-11-09 21:30:36 +01:00
Christian Kratky	f894622884	Merge branch 'master' into feature/Single_Connection_Monitoring_Task	2020-11-09 21:29:38 +01:00
Christian	88b0af9b21	Merge pull request #1023 from StefanOssendorf/fix/compile-error Fix: Compile error, cancellation token removed since the method does not support it	2020-11-09 21:11:48 +01:00
Christian Kratky	e1bf9de347	Add support for topic alias.	2020-11-09 21:10:05 +01:00
Christian Kratky	6c15693456	Add support for TopicAlias in application message builder.	2020-11-09 17:22:32 +01:00
Stefan Ossendorf	4608930a37	Cancellation token removed since the method does not support it Cancellation token removed because the SendAsync() method does not support it.	2020-11-08 14:31:01 +01:00
Christian Kratky	eaf1195f95	Cleanup Unit Tests.	2020-11-06 21:00:25 +01:00
Christian Kratky	a35dee9352	Update docs.	2020-11-06 20:03:33 +01:00
Christian	6cef746ed9	Merge pull request #1021 from nayato/max-qos Add support for Maximum QoS property on CONNACK	2020-11-06 20:00:09 +01:00
Max Gortman	344cf674e6	PR fixes	2020-11-05 16:55:50 -08:00
Christian Kratky	26af205ab0	Update docs.	2020-11-04 21:29:26 +01:00
Christian Kratky	06c9d27c87	Fixed bug in PubRel packet generation (MQTTv5 only).	2020-11-04 21:28:40 +01:00
Max Gortman	14224e4180	Add support for Maximum QoS property on CONNACK	2020-11-03 12:19:38 -08:00
Christian Kratky	b954c9512e	Fix swagger configuration.	2020-11-02 22:03:47 +01:00
Christian Kratky	fb2be79673	Remove not used timeout for receiving.	2020-11-02 21:45:23 +01:00
Christian Kratky	44b7133a1c	Improve keep alive tests.	2020-11-02 21:17:31 +01:00
Christian Kratky	2f0513212e	Merge branch 'master' into feature/Single_Connection_Monitoring_Task	2020-11-01 12:35:59 +01:00
Christian Kratky	1a9460776b	Update docs.	2020-11-01 12:03:19 +01:00
Christian Kratky	2716db04e3	Move the RPC topic validation to the topic generation strategy.	2020-11-01 12:00:12 +01:00
Christian Kratky	3e4f4a59a8	Improve Unit Tests.	2020-11-01 11:58:43 +01:00
Christian Kratky	24f0ea01f5	Improve session takeover and keep alive handling.	2020-10-31 20:59:41 +01:00
Christian Kratky	1625aadae9	Improve disconnect reason transfer to client (especially for session take over).	2020-10-31 11:43:14 +01:00
Christian Kratky	e800901b4c	Merge branch 'master' into feature/Single_Connection_Monitoring_Task	2020-10-31 11:33:54 +01:00
Christian Kratky	34ae54d542	Improve Unit Tests.	2020-10-31 11:33:44 +01:00
Christian Kratky	838d50c1d3	Remove file which is not part of the solution.	2020-10-31 11:27:46 +01:00
Christian Kratky	558d281a33	Refactor TLS 1.3 support.	2020-10-31 11:23:14 +01:00
Christian Kratky	f8c956a9e2	Merge remote-tracking branch 'origin/master'	2020-10-31 11:14:07 +01:00
Christian	9a6823597e	Merge pull request #1020 from Dvergatal/master Added support for Tls1.3	2020-10-31 11:13:50 +01:00
Christian Kratky	42c1155bee	Fix nullref exception in connection handler.	2020-10-30 23:51:11 +01:00
Christian Kratky	f773257c86	Improve exception handling in AsyncQueue.	2020-10-30 20:43:39 +01:00
Christian Kratky	4e9df98817	Improve test environment.	2020-10-30 20:43:02 +01:00
Christian Kratky	3208045baa	Extend application message builder.	2020-10-30 20:42:52 +01:00
Piotr Łobacz	7274f4390c	added support for Tls1.3 protocol	2020-10-30 12:45:57 +01:00
Dvergatal	11c8abfd54	Merge pull request #1 from chkr1011/master Merging with mainline.	2020-10-30 11:16:09 +01:00
Christian Kratky	f606a5996b	Merge remote-tracking branch 'origin/master'	2020-10-30 00:26:40 +01:00
Christian Kratky	58ad599783	Improve disconnect code of client.	2020-10-30 00:23:45 +01:00
Christian Kratky	ccd102a59f	Refactor code.	2020-10-30 00:21:08 +01:00
Christian Kratky	05101f0e0e	Improve exception handling of AsyncLock.	2020-10-30 00:19:57 +01:00
Christian Kratky	f9630ef347	Improve internal session/connection management and connection takeover.	2020-10-30 00:19:30 +01:00
Christian Kratky	c5b7735a2c	Improve cancellation token handling for client connections (Server).	2020-10-29 20:02:03 +01:00
HansM	12fca2f05a	Merge pull request #1015 from Jay424/patch-1 Fixed evaluation of IgnoreCertificateRevocationErrors to correctly se…	2020-10-29 11:34:23 +01:00
Christian Kratky	b7fb0c1002	Refactor package object model.	2020-10-28 23:11:12 +01:00
Jay424	3ea281ff84	Updated release notes	2020-10-28 17:58:48 +01:00
Jay424	c778cd7a0f	Fixed evaluation of IgnoreCertificateRevocationErrors to correctly set SslClientAuthenticationOptions.CertificateRevocationCheckMode The if was just flipped.	2020-10-28 17:14:09 +01:00
Christian Kratky	adce5662eb	Prepare docs for next release.	2020-10-24 12:22:03 +02:00