Fix UnitTests

Fix ManagedMqttClient missing call to unsubscribe topics

.gitignore

@@ -291,3 +291,5 @@ __pycache__/
 Build/nuget.exe
 *.js
 *.map
+
+/Tests/MQTTnet.TestApp.NetCore/RetainedMessages.json

Build/MQTTnet.AspNetCore.nuspec

@@ -2,7 +2,7 @@
 <package >
   <metadata>
     <id>MQTTnet.AspNetCore</id>
-    <version>2.5.3</version>
+    <version>2.7.3</version>
     <authors>Christian Kratky</authors>
     <owners>Christian Kratky</owners>
     <licenseUrl>https://github.com/chkr1011/MQTTnet/blob/master/LICENSE</licenseUrl>
@@ -10,13 +10,13 @@
     <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>This is a support library to integrate MQTTnet into AspNetCore.</description>
-    <releaseNotes>* Updated to MQTTnet 2.5.3.
+    <releaseNotes>* Updated to MQTTnet 2.7.3.
     </releaseNotes>
-    <copyright>Copyright Christian Kratky 2016-2017</copyright>
+    <copyright>Copyright Christian Kratky 2016-2018</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
     <dependencies>
       <group targetFramework="netstandard2.0">
-        <dependency id="MQTTnet" version="2.5.3-rc1" />
+        <dependency id="MQTTnet" version="2.7.3" />
       </group>
     </dependencies>
   </metadata>

Build/MQTTnet.Extensions.Rpc.nuspec

@@ -0,0 +1,47 @@
+<?xml version="1.0"?>
+<package >
+  <metadata>
+    <id>MQTTnet.Extensions.Rpc</id>
+    <version>2.6.0</version>
+    <authors>Christian Kratky</authors>
+    <owners>Christian Kratky</owners>
+    <licenseUrl>https://github.com/chkr1011/MQTTnet/blob/master/LICENSE</licenseUrl>
+    <projectUrl>https://github.com/chkr1011/MQTTnet</projectUrl>
+    <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
+    <requireLicenseAcceptance>false</requireLicenseAcceptance>
+    <description>This is a extension library which allows executing synchronous device calls including a response using MQTTnet.</description>
+    <releaseNotes>* Initial version.
+    </releaseNotes>
+    <copyright>Copyright Christian Kratky 2016-2017</copyright>
+    <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
+    <dependencies>
+      <group targetFramework="netstandard2.0">
+        <dependency id="MQTTnet" version="2.6.0-rc1" />
+      </group>
+      <group targetFramework="netstandard1.3">
+        <dependency id="MQTTnet" version="2.6.0-rc1" />  
+      </group>
+
+      <group targetFramework="netstandard2.0">
+        <dependency id="MQTTnet" version="2.6.0-rc1" />
+      </group>
+      
+      <group targetFramework="uap10.0">
+        <dependency id="MQTTnet" version="2.6.0-rc1" />
+      </group>
+        
+      <group targetFramework="net452">
+        <dependency id="MQTTnet" version="2.6.0-rc1" />
+      </group>
+
+      <group targetFramework="net461">
+        <dependency id="MQTTnet" version="2.6.0-rc1" />
+      </group>
+    </dependencies>
+  </metadata>
+
+  <files>
+    <!-- .NET Standard 2.0 -->
+    <file src="..\Frameworks\MQTTnet.AspNetCore\bin\Release\netstandard2.0\MQTTnet.AspNetCore.*" target="lib\netstandard2.0\"/>
+  </files>
+</package>

Build/MQTTnet.nuspec

@@ -2,7 +2,7 @@
 <package >
   <metadata>
     <id>MQTTnet</id>
-    <version>2.5.3</version>
+    <version>2.7.3</version>
     <authors>Christian Kratky</authors>
     <owners>Christian Kratky</owners>
     <licenseUrl>https://github.com/chkr1011/MQTTnet/blob/master/LICENSE</licenseUrl>
@@ -10,11 +10,16 @@
     <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>MQTTnet is a high performance .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker).</description>
-    <releaseNotes>* [Core] Removed all dependencies to other libraries (BREAKING CHANGE!).
+    <releaseNotes>* [Core] Add several new extension methods.
-* [Core] Updated SDK libraries.
+* [Client] Fixed an issue in _ManagedMqttClientOptionsBuilder_ when using _WithClientOptions_ and an options builder.
-* [Client] Fixed broken support for WebSocketSecure connections (Thanks to @StAI).
+* [Client] Added the "IsStarted" property for the managed client.
+* [Client] Optimized stream buffer for UWP apps.
+* [Client] Added the _BufferSize_ to the TCP options.
+* [Client] Fixed a race condition which leads to exceptions when reconnecting rapidly.
+* [Server] Fixed a race condition which leads to exceptions when clients are reconnecting rapidly.
+* [Core] Fixed some issues in stream and socket handling.
     </releaseNotes>
-    <copyright>Copyright Christian Kratky 2016-2017</copyright>
+    <copyright>Copyright Christian Kratky 2016-2018</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
     <dependencies>
 
@@ -46,23 +51,18 @@
   </metadata>
 
   <files>
+    
     <!-- .NET Standard 1.3 -->
-    <file src="..\Frameworks\MQTTnet.Netstandard\bin\Release\netstandard1.3\MQTTnet.Core.*" target="lib\netstandard1.3\"/>
     <file src="..\Frameworks\MQTTnet.Netstandard\bin\Release\netstandard1.3\MQTTnet.*" target="lib\netstandard1.3\"/>
     
     <!-- .NET Standard 2.0 -->
-    <file src="..\Frameworks\MQTTnet.Netstandard\bin\Release\netstandard2.0\MQTTnet.Core.*" target="lib\netstandard2.0\"/>
     <file src="..\Frameworks\MQTTnet.Netstandard\bin\Release\netstandard2.0\MQTTnet.*" target="lib\netstandard2.0\"/>
 
     <!-- Universal Windows -->
-    <file src="..\Frameworks\MQTTnet.Netstandard\bin\Release\uap10.0\MQTTnet.Core.*" target="lib\uap10.0\"/>
     <file src="..\Frameworks\MQTTnet.Netstandard\bin\Release\uap10.0\MQTTnet.*" target="lib\uap10.0\"/>
 
     <!-- .NET Framework -->
-    <file src="..\Frameworks\MQTTnet.Netstandard\bin\Release\net452\MQTTnet.Core.*" target="lib\net452\"/>
     <file src="..\Frameworks\MQTTnet.Netstandard\bin\Release\net452\MQTTnet.*" target="lib\net452\"/>
-
-    <file src="..\Frameworks\MQTTnet.Netstandard\bin\Release\net461\MQTTnet.Core.*" target="lib\net461\"/>
     <file src="..\Frameworks\MQTTnet.Netstandard\bin\Release\net461\MQTTnet.*" target="lib\net461\"/>
     
   </files>

Build/build.ps1

@@ -1,6 +1,7 @@
 param([string]$assemblyVersion, [string]$nugetVersion)
 
-if ([string]::IsNullOrEmpty($version)) {$version = "0.0.1"}
+if ([string]::IsNullOrEmpty($assemblyVersion)) {$assemblyVersion = "0.0.1"}
+if ([string]::IsNullOrEmpty($nugetVersion)) {$nugetVersion = "0.0.1"}
 
 $vswhere = ${Env:\ProgramFiles(x86)} + '\Microsoft Visual Studio\Installer\vswhere'
 
@@ -8,16 +9,27 @@ $path = &$vswhere -latest -products * -requires Microsoft.Component.MSBuild -pro
 if ($path) {
     $msbuild = join-path $path 'MSBuild\15.0\Bin\MSBuild.exe'
 
-    &$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net452" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+	# Build the core library
-    &$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net461" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+    &$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net452" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
-    &$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard1.3" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+    &$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net461" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
-    &$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+    &$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard1.3" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
-    &$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="uap10.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+    &$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=".\..\..\Build\codeSigningKey.pfx"
+    &$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.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"
     
-	&$msbuild ..\Frameworks\MQTTnet.AspNetCore\MQTTnet.AspNetCore.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+	# Build the ASP.NET Core 2.0 extension
+	&$msbuild ..\Frameworks\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"
+
+	# Build the RPC extension
+	&$msbuild ..\Extensions\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net452" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+    &$msbuild ..\Extensions\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="net461" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+    &$msbuild ..\Extensions\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard1.3" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+    &$msbuild ..\Extensions\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="netstandard2.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+    &$msbuild ..\Extensions\MQTTnet.Extensions.Rpc\MQTTnet.Extensions.Rpc.csproj /t:Build /p:Configuration="Release" /p:TargetFramework="uap10.0" /p:FileVersion=$assemblyVersion /p:AssemblyVersion=$assemblyVersion /verbosity:m
+
+    Remove-Item .\NuGet -Force -Recurse -ErrorAction SilentlyContinue
 
-    Remove-Item .\NuGet -Force -Recurse
     New-Item -ItemType Directory -Force -Path .\NuGet
     .\NuGet.exe pack MQTTnet.nuspec -Verbosity detailed -Symbols -OutputDir "NuGet" -Version $nugetVersion
     .\NuGet.exe pack MQTTnet.AspNetCore.nuspec -Verbosity detailed -Symbols -OutputDir "NuGet" -Version $nugetVersion
+	.\NuGet.exe pack MQTTnet.Extensions.Rpc.nuspec -Verbosity detailed -Symbols -OutputDir "NuGet" -Version $nugetVersion
 }

Documents/Import_CodeSigningKey.md

@@ -0,0 +1,9 @@
+# Import codeSigningKey.pfx
+In order to import the key for code signing on a new developer machine use the following command within the VS developer command line:
+
+> sn –i codeSigningKey.pfx VS_KEY_EFCA4C5B6DFD4B4F
+
+The container name may be different.
+
+# Check if the assembly has a strong name
+> sn -vf MQTTnet.dll

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

@@ -0,0 +1,31 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>netstandard1.3;netstandard2.0;net452;net461;uap10.0</TargetFrameworks>
+    <AssemblyVersion>0.0.0.0</AssemblyVersion>
+    <FileVersion>0.0.0.0</FileVersion>
+    <Product />
+    <Company />
+    <Authors />
+    <PackageId />
+    <Version>0.0.0.0</Version>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0'">
+    <CopyLocalLockFileAssemblies>false</CopyLocalLockFileAssemblies>
+    <NugetTargetMoniker>UAP,Version=v10.0</NugetTargetMoniker>
+    <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
+    <TargetPlatformVersion>10.0.16299.0</TargetPlatformVersion>
+    <TargetPlatformMinVersion>10.0.10240.0</TargetPlatformMinVersion>
+    <TargetFrameworkIdentifier>.NETCore</TargetFrameworkIdentifier>
+    <TargetFrameworkVersion>v5.0</TargetFrameworkVersion>
+    <DefineConstants>$(DefineConstants);WINDOWS_UWP</DefineConstants>
+    <DefaultLanguage>en</DefaultLanguage>
+    <LanguageTargets>$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets</LanguageTargets>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\Frameworks\MQTTnet.Netstandard\MQTTnet.NetStandard.csproj" />
+  </ItemGroup>
+
+</Project>

Extensions/MQTTnet.Extensions.Rpc/MqttRpcClient.cs

@@ -0,0 +1,101 @@
+using System;
+using System.Collections.Concurrent;
+using System.Threading.Tasks;
+using MQTTnet.Client;
+using MQTTnet.Internal;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Extensions.Rpc
+{
+    public sealed class MqttRpcClient : IDisposable
+    {
+        private const string ResponseTopic = "$MQTTnet.RPC/+/+/response";
+        private readonly ConcurrentDictionary<string, TaskCompletionSource<byte[]>> _waitingCalls = new ConcurrentDictionary<string, TaskCompletionSource<byte[]>>();
+        private readonly IMqttClient _mqttClient;
+        private bool _isEnabled;
+
+        public MqttRpcClient(IMqttClient mqttClient)
+        {
+            _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
+
+            _mqttClient.ApplicationMessageReceived += OnApplicationMessageReceived;
+        }
+
+        public async Task EnableAsync()
+        {
+            await _mqttClient.SubscribeAsync(new TopicFilterBuilder().WithTopic(ResponseTopic).WithAtLeastOnceQoS().Build());
+            _isEnabled = true;
+        }
+
+        public async Task DisableAsync()
+        {
+            await _mqttClient.UnsubscribeAsync(ResponseTopic);
+            _isEnabled = false;
+        }
+
+        public async Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
+        {
+            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 (!_isEnabled)
+            {
+                throw new InvalidOperationException("The RPC client is not enabled.");
+            }
+
+            var requestTopic = $"$MQTTnet.RPC/{Guid.NewGuid():N}/{methodName}";
+            var responseTopic = requestTopic + "/response";
+
+            var requestMessage = new MqttApplicationMessageBuilder()
+                .WithTopic(requestTopic)
+                .WithPayload(payload)
+                .WithQualityOfServiceLevel(qualityOfServiceLevel)
+                .Build();
+
+            try
+            {
+                var tcs = new TaskCompletionSource<byte[]>();
+                if (!_waitingCalls.TryAdd(responseTopic, tcs))
+                {
+                    throw new InvalidOperationException();
+                }
+
+                await _mqttClient.PublishAsync(requestMessage);
+                return await tcs.Task.TimeoutAfter(timeout);
+            }
+            finally
+            {
+                _waitingCalls.TryRemove(responseTopic, out _);
+            }
+        }
+
+        private void OnApplicationMessageReceived(object sender, MqttApplicationMessageReceivedEventArgs eventArgs)
+        {
+            if (!_waitingCalls.TryRemove(eventArgs.ApplicationMessage.Topic, out TaskCompletionSource<byte[]> tcs))
+            {
+                return;
+            }
+
+            if (tcs.Task.IsCompleted || tcs.Task.IsCanceled)
+            {
+                return;
+            }
+
+            tcs.TrySetResult(eventArgs.ApplicationMessage.Payload);
+        }
+
+        public void Dispose()
+        {
+            foreach (var tcs in _waitingCalls)
+            {
+                tcs.Value.SetCanceled();
+            }
+
+            _waitingCalls.Clear();
+        }
+    }
+}

Extensions/MQTTnet.Extensions.Rpc/SampleCCode.c

@@ -0,0 +1 @@
+

Frameworks/MQTTnet.AspnetCore/ApplicationBuilderExtensions.cs

@@ -1,8 +1,8 @@
 using System;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.DependencyInjection;
-using MQTTnet.Core.Server;
 using System.Linq;
+using MQTTnet.Server;
 
 namespace MQTTnet.AspNetCore
 {

Frameworks/MQTTnet.AspnetCore/MQTTnet.AspnetCore.csproj

@@ -2,14 +2,23 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <AssemblyVersion>2.5.2.0</AssemblyVersion>
+    <AssemblyVersion>0.0.0.0</AssemblyVersion>
-    <FileVersion>2.5.2.0</FileVersion>
+    <FileVersion>0.0.0.0</FileVersion>
+    <Version>0.0.0.0</Version>
+    <Product />
+    <Company />
+    <Authors />
+    <PackageId />
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
+    <DefineConstants>RELEASE;NETSTANDARD2_0</DefineConstants>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.Http.Abstractions" Version="2.0.0" />
+    <PackageReference Include="Microsoft.AspNetCore.Http.Abstractions" Version="2.0.1" />
-    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.0.0" />
+    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.0.1" />
-    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="2.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="2.0.1" />
   </ItemGroup>
 
   <ItemGroup>

Frameworks/MQTTnet.AspnetCore/MqttHostedServer.cs

@@ -3,17 +3,17 @@ using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Hosting;
-using MQTTnet.Core.Adapter;
+using MQTTnet.Adapter;
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Diagnostics;
-using MQTTnet.Core.Server;
+using MQTTnet.Server;
 
 namespace MQTTnet.AspNetCore
 {
     public class MqttHostedServer : MqttServer, IHostedService
     {
-        private readonly MqttServerOptions _options;
+        private readonly IMqttServerOptions _options;
 
-        public MqttHostedServer(MqttServerOptions options, IEnumerable<IMqttServerAdapter> adapters, IMqttNetLogger logger) : base(adapters, logger)
+        public MqttHostedServer(IMqttServerOptions options, IEnumerable<IMqttServerAdapter> adapters, IMqttNetLogger logger) : base(adapters, logger)
         {
             _options = options ?? throw new ArgumentNullException(nameof(options));
         }

Frameworks/MQTTnet.AspnetCore/MqttWebSocketServerAdapter.cs

@@ -1,18 +1,18 @@
 using System;
 using System.Net.WebSockets;
 using System.Threading.Tasks;
-using MQTTnet.Core.Adapter;
+using MQTTnet.Adapter;
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Diagnostics;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Serializer;
-using MQTTnet.Core.Server;
+using MQTTnet.Server;
 
 namespace MQTTnet.AspNetCore
 {
-    public class MqttWebSocketServerAdapter : IMqttServerAdapter, IDisposable
+    public sealed class MqttWebSocketServerAdapter : IMqttServerAdapter, IDisposable
     {
         public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
 
-        public Task StartAsync(MqttServerOptions options)
+        public Task StartAsync(IMqttServerOptions options)
         {
             return Task.CompletedTask;
         }

Frameworks/MQTTnet.AspnetCore/MqttWebSocketServerChannel.cs

@@ -3,7 +3,7 @@ using System.IO;
 using System.Net.WebSockets;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Core.Channel;
+using MQTTnet.Channel;
 using MQTTnet.Implementations;
 
 namespace MQTTnet.AspNetCore

Frameworks/MQTTnet.AspnetCore/ServiceCollectionExtensions.cs

@@ -1,15 +1,15 @@
 using System;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
-using MQTTnet.Core.Adapter;
+using MQTTnet.Adapter;
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Diagnostics;
-using MQTTnet.Core.Server;
+using MQTTnet.Server;
 
 namespace MQTTnet.AspNetCore
 {
     public static class ServiceCollectionExtensions
     {
-        public static IServiceCollection AddHostedMqttServer(this IServiceCollection services, MqttServerOptions options)
+        public static IServiceCollection AddHostedMqttServer(this IServiceCollection services, IMqttServerOptions options)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 

Frameworks/MQTTnet.NetStandard/Adapter/IMqttChannelAdapter.cs

@@ -2,12 +2,12 @@
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Core.Packets;
+using MQTTnet.Packets;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Serializer;
 
-namespace MQTTnet.Core.Adapter
+namespace MQTTnet.Adapter
 {
-    public interface IMqttChannelAdapter
+    public interface IMqttChannelAdapter : IDisposable
     {
         IMqttPacketSerializer PacketSerializer { get; }
 

Frameworks/MQTTnet.NetStandard/Adapter/IMqttServerAdapter.cs

@@ -1,14 +1,14 @@
 using System;
 using System.Threading.Tasks;
-using MQTTnet.Core.Server;
+using MQTTnet.Server;
 
-namespace MQTTnet.Core.Adapter
+namespace MQTTnet.Adapter
 {
     public interface IMqttServerAdapter
     {
         event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
 
-        Task StartAsync(MqttServerOptions options);
+        Task StartAsync(IMqttServerOptions options);
         Task StopAsync();
     }
 }

Frameworks/MQTTnet.NetStandard/Adapter/MqttChannelAdapter.cs

@@ -1,22 +1,25 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Net.Sockets;
 using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Core.Channel;
+using MQTTnet.Channel;
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Diagnostics;
-using MQTTnet.Core.Exceptions;
+using MQTTnet.Exceptions;
-using MQTTnet.Core.Internal;
+using MQTTnet.Internal;
-using MQTTnet.Core.Packets;
+using MQTTnet.Packets;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Serializer;
 
-namespace MQTTnet.Core.Adapter
+namespace MQTTnet.Adapter
 {
-    public class MqttChannelAdapter : IMqttChannelAdapter
+    public sealed class MqttChannelAdapter : IMqttChannelAdapter
     {
         private const uint ErrorOperationAborted = 0x800703E3;
+        private const int ReadBufferSize = 4096;  // TODO: Move buffer size to config
 
+        private bool _isDisposed;
         private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1, 1);
         private readonly IMqttNetLogger _logger;
         private readonly IMqttChannel _channel;
@@ -30,29 +33,38 @@ namespace MQTTnet.Core.Adapter
 
         public IMqttPacketSerializer PacketSerializer { get; }
 
-        public async Task ConnectAsync(TimeSpan timeout)
+        public Task ConnectAsync(TimeSpan timeout)
         {
-            _logger.Info<MqttChannelAdapter>("Connecting [Timeout={0}]", timeout);
+            ThrowIfDisposed();
+            _logger.Trace<MqttChannelAdapter>("Connecting [Timeout={0}]", timeout);
 
-            await ExecuteAndWrapExceptionAsync(() => _channel.ConnectAsync().TimeoutAfter(timeout));
+            return ExecuteAndWrapExceptionAsync(() => _channel.ConnectAsync().TimeoutAfter(timeout));
         }
 
-        public async Task DisconnectAsync(TimeSpan timeout)
+        public Task DisconnectAsync(TimeSpan timeout)
         {
-            _logger.Info<MqttChannelAdapter>("Disconnecting [Timeout={0}]", timeout);
+            ThrowIfDisposed();
+            _logger.Trace<MqttChannelAdapter>("Disconnecting [Timeout={0}]", timeout);
 
-            await ExecuteAndWrapExceptionAsync(() => _channel.DisconnectAsync().TimeoutAfter(timeout));
+            return ExecuteAndWrapExceptionAsync(() => _channel.DisconnectAsync().TimeoutAfter(timeout));
         }
 
-        public async Task SendPacketsAsync(TimeSpan timeout, CancellationToken cancellationToken, IEnumerable<MqttBasePacket> packets)
+        public Task SendPacketsAsync(TimeSpan timeout, CancellationToken cancellationToken, IEnumerable<MqttBasePacket> packets)
         {
-            await ExecuteAndWrapExceptionAsync(async () =>
+            ThrowIfDisposed();
+
+            return ExecuteAndWrapExceptionAsync(async () =>
             {
                 await _semaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
                 try
                 {
                     foreach (var packet in packets)
                     {
+                        if (cancellationToken.IsCancellationRequested)
+                        {
+                            return;
+                        }
+
                         if (packet == null)
                         {
                             continue;
@@ -60,8 +72,21 @@ namespace MQTTnet.Core.Adapter
 
                         _logger.Trace<MqttChannelAdapter>("TX >>> {0} [Timeout={1}]", packet, timeout);
 
-                        var writeBuffer = PacketSerializer.Serialize(packet);
+                        var chunks = PacketSerializer.Serialize(packet);
-                        await _channel.SendStream.WriteAsync(writeBuffer, 0, writeBuffer.Length, cancellationToken).ConfigureAwait(false);
+                        foreach (var chunk in chunks)
+                        {
+                            if (cancellationToken.IsCancellationRequested)
+                            {
+                                return;
+                            }
+
+                            await _channel.SendStream.WriteAsync(chunk.Array, chunk.Offset, chunk.Count, cancellationToken).ConfigureAwait(false);
+                        }
+                    }
+
+                    if (cancellationToken.IsCancellationRequested)
+                    {
+                        return;
                     }
 
                     if (timeout > TimeSpan.Zero)
@@ -82,6 +107,8 @@ namespace MQTTnet.Core.Adapter
 
         public async Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
+            ThrowIfDisposed();
+
             MqttBasePacket packet = null;
             await ExecuteAndWrapExceptionAsync(async () =>
             {
@@ -102,7 +129,7 @@ namespace MQTTnet.Core.Adapter
                         throw new TaskCanceledException();
                     }
 
-                    packet = PacketSerializer.Deserialize(receivedMqttPacket);
+                    packet = PacketSerializer.Deserialize(receivedMqttPacket.Header, receivedMqttPacket.Body);
                     if (packet == null)
                     {
                         throw new MqttProtocolViolationException("Received malformed packet.");
@@ -114,14 +141,14 @@ namespace MQTTnet.Core.Adapter
                 {
                     receivedMqttPacket?.Dispose();
                 }
-            });
+            }).ConfigureAwait(false);
 
             return packet;
         }
 
         private static async Task<ReceivedMqttPacket> ReceiveAsync(Stream stream, CancellationToken cancellationToken)
         {
-            var header = MqttPacketReader.ReadHeaderFromSource(stream, cancellationToken);
+            var header = await MqttPacketReader.ReadHeaderAsync(stream, cancellationToken).ConfigureAwait(false);
             if (header == null)
             {
                 return null;
@@ -129,19 +156,36 @@ namespace MQTTnet.Core.Adapter
 
             if (header.BodyLength == 0)
             {
-                return new ReceivedMqttPacket(header, new MemoryStream(0));
+                return new ReceivedMqttPacket(header, new MemoryStream(new byte[0], false));
             }
 
-            var body = new byte[header.BodyLength];
+            var body = header.BodyLength <= ReadBufferSize ? new MemoryStream(header.BodyLength) : new MemoryStream();
 
-            var offset = 0;
+            var buffer = new byte[ReadBufferSize];
-            do
+            while (body.Length < header.BodyLength)
             {
-                var readBytesCount = await stream.ReadAsync(body, offset, body.Length - offset, cancellationToken).ConfigureAwait(false);
+                var bytesLeft = header.BodyLength - (int)body.Length;
-                offset += readBytesCount;
+                if (bytesLeft > buffer.Length)
-            } while (offset < header.BodyLength);
+                {
+                    bytesLeft = buffer.Length;
+                }
 
-            return new ReceivedMqttPacket(header, new MemoryStream(body, 0, body.Length));
+                var readBytesCount = await stream.ReadAsync(buffer, 0, bytesLeft, cancellationToken).ConfigureAwait(false);
+
+                // Check if the client closed the connection before sending the full body.
+                if (readBytesCount == 0)
+                {
+                    throw new MqttCommunicationException("Connection closed while reading remaining packet body.");
+                }
+
+                // Here is no need to await because internally only an array is used and no real I/O operation is made.
+                // Using async here will only generate overhead.
+                body.Write(buffer, 0, readBytesCount);
+            }
+
+            body.Seek(0L, SeekOrigin.Begin);
+
+            return new ReceivedMqttPacket(header, body);
         }
 
         private static async Task ExecuteAndWrapExceptionAsync(Func<Task> action)
@@ -175,10 +219,37 @@ namespace MQTTnet.Core.Adapter
 
                 throw new MqttCommunicationException(comException);
             }
+            catch (IOException exception)
+            {
+                if (exception.InnerException is SocketException socketException)
+                {
+                    if (socketException.SocketErrorCode == SocketError.ConnectionAborted)
+                    {
+                        throw new OperationCanceledException();
+                    }
+                }
+
+                throw new MqttCommunicationException(exception);
+            }
             catch (Exception exception)
             {
                 throw new MqttCommunicationException(exception);
             }
         }
+
+        public void Dispose()
+        {
+            _isDisposed = true;
+            _semaphore?.Dispose();
+            _channel?.Dispose();
+        }
+
+        private void ThrowIfDisposed()
+        {
+            if (_isDisposed)
+            {
+                throw new ObjectDisposedException(nameof(MqttChannelAdapter));
+            }
+        }
     }
 }

Frameworks/MQTTnet.NetStandard/Adapter/MqttConnectingFailedException.cs

@@ -1,7 +1,7 @@
-using MQTTnet.Core.Exceptions;
+using MQTTnet.Exceptions;
-using MQTTnet.Core.Protocol;
+using MQTTnet.Protocol;
 
-namespace MQTTnet.Core.Adapter
+namespace MQTTnet.Adapter
 {
     public class MqttConnectingFailedException : MqttCommunicationException
     {

Frameworks/MQTTnet.NetStandard/Adapter/MqttServerAdapterClientAcceptedEventArgs.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Threading.Tasks;
 
-namespace MQTTnet.Core.Adapter
+namespace MQTTnet.Adapter
 {
     public class MqttServerAdapterClientAcceptedEventArgs : EventArgs
     {

Frameworks/MQTTnet.NetStandard/Adapter/ReceivedMqttPacket.cs

@@ -1,8 +1,8 @@
 using System;
 using System.IO;
-using MQTTnet.Core.Packets;
+using MQTTnet.Packets;
 
-namespace MQTTnet.Core.Adapter
+namespace MQTTnet.Adapter
 {
     public sealed class ReceivedMqttPacket : IDisposable
     {

Frameworks/MQTTnet.NetStandard/ApplicationMessagePublisherExtensions.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Threading.Tasks;
+using MQTTnet.Protocol;
+
+namespace MQTTnet
+{
+    public static class ApplicationMessagePublisherExtensions
+    {
+        public static Task PublishAsync(this IApplicationMessagePublisher publisher, params MqttApplicationMessage[] applicationMessages)
+        {
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
+            if (applicationMessages == null) throw new ArgumentNullException(nameof(applicationMessages));
+
+            return publisher.PublishAsync(applicationMessages);
+        }
+
+        public static Task PublishAsync(this IApplicationMessagePublisher publisher, string topic)
+        {
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+            
+            return publisher.PublishAsync(new MqttApplicationMessageBuilder().WithTopic(topic).Build());
+        }
+
+        public static Task PublishAsync(this IApplicationMessagePublisher publisher, string topic, string payload)
+        {
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
+            return publisher.PublishAsync(new MqttApplicationMessageBuilder().WithTopic(topic).WithPayload(payload).Build());
+        }
+
+        public static Task PublishAsync(this IApplicationMessagePublisher publisher, string topic, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
+        {
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
+            return publisher.PublishAsync(new MqttApplicationMessageBuilder().WithTopic(topic).WithPayload(payload).WithQualityOfServiceLevel(qualityOfServiceLevel).Build());
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/Channel/IMqttChannel.cs

@@ -1,9 +1,10 @@
-using System.Threading.Tasks;
+using System;
 using System.IO;
+using System.Threading.Tasks;
 
-namespace MQTTnet.Core.Channel
+namespace MQTTnet.Channel
 {
-    public interface IMqttChannel
+    public interface IMqttChannel : IDisposable
     {
         Stream SendStream { get; }
         Stream ReceiveStream { get; }

Frameworks/MQTTnet.NetStandard/Client/IMqttClient.cs

@@ -1,11 +1,10 @@
 using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
-using MQTTnet.Core.Packets;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
-    public interface IMqttClient : IApplicationMessageReceiver, IApplicationMessagePublisher
+    public interface IMqttClient : IApplicationMessageReceiver, IApplicationMessagePublisher, IDisposable
     {
         bool IsConnected { get; }
 
@@ -16,6 +15,6 @@ namespace MQTTnet.Core.Client
         Task DisconnectAsync();
 
         Task<IList<MqttSubscribeResult>> SubscribeAsync(IEnumerable<TopicFilter> topicFilters);
-        Task UnsubscribeAsync(IEnumerable<string> topicFilters);
+        Task UnsubscribeAsync(IEnumerable<string> topics);
     }
 }

Frameworks/MQTTnet.NetStandard/Client/IMqttClientAdapterFactory.cs

@@ -1,7 +1,7 @@
-using MQTTnet.Core.Adapter;
+using MQTTnet.Adapter;
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Diagnostics;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public interface IMqttClientAdapterFactory
     {

Frameworks/MQTTnet.NetStandard/Client/IMqttClientChannelOptions.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public interface IMqttClientChannelOptions
     {

Frameworks/MQTTnet.NetStandard/Client/IMqttClientCredentials.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public interface IMqttClientCredentials
     {

Frameworks/MQTTnet.NetStandard/Client/IMqttClientFactory.cs

@@ -1,7 +1,7 @@
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Diagnostics;
-using MQTTnet.Core.ManagedClient;
+using MQTTnet.ManagedClient;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public interface IMqttClientFactory
     {

Frameworks/MQTTnet.NetStandard/Client/IMqttClientOptions.cs

@@ -1,7 +1,7 @@
 using System;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Serializer;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public interface IMqttClientOptions
     {
@@ -13,6 +13,8 @@ namespace MQTTnet.Core.Client
         
         TimeSpan CommunicationTimeout { get; }
         TimeSpan KeepAlivePeriod { get; }
+        TimeSpan? KeepAliveSendInterval { get; set; }
+
         MqttProtocolVersion ProtocolVersion { get; }
 
         IMqttClientChannelOptions ChannelOptions { get; }

Frameworks/MQTTnet.NetStandard/Client/MqttClient.cs

@@ -1,36 +1,39 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Core.Adapter;
+using MQTTnet.Adapter;
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Diagnostics;
-using MQTTnet.Core.Exceptions;
+using MQTTnet.Exceptions;
-using MQTTnet.Core.Internal;
+using MQTTnet.Internal;
-using MQTTnet.Core.Packets;
+using MQTTnet.Packets;
-using MQTTnet.Core.Protocol;
+using MQTTnet.Protocol;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttClient : IMqttClient
     {
-        private readonly HashSet<ushort> _unacknowledgedPublishPackets = new HashSet<ushort>();
+        private readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
-
+        private readonly Stopwatch _sendTracker = new Stopwatch();
+        private readonly SemaphoreSlim _disconnectLock = new SemaphoreSlim(1, 1);
         private readonly IMqttClientAdapterFactory _adapterFactory;
         private readonly MqttPacketDispatcher _packetDispatcher;
         private readonly IMqttNetLogger _logger;
 
         private IMqttClientOptions _options;
         private bool _isReceivingPackets;
-        private int _latestPacketIdentifier;
         private CancellationTokenSource _cancellationTokenSource;
+        private Task _packetReceiverTask;
+        private Task _keepAliveMessageSenderTask;
         private IMqttChannelAdapter _adapter;
 
         public MqttClient(IMqttClientAdapterFactory channelFactory, IMqttNetLogger logger)
         {
             _adapterFactory = channelFactory ?? throw new ArgumentNullException(nameof(channelFactory));
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
-            
+
             _packetDispatcher = new MqttPacketDispatcher(logger);
         }
 
@@ -51,23 +54,25 @@ namespace MQTTnet.Core.Client
             {
                 _options = options;
                 _cancellationTokenSource = new CancellationTokenSource();
-                _latestPacketIdentifier = 0;
+                _packetIdentifierProvider.Reset();
                 _packetDispatcher.Reset();
 
                 _adapter = _adapterFactory.CreateClientAdapter(options.ChannelOptions, _logger);
-                
+
                 _logger.Trace<MqttClient>("Trying to connect with server.");
                 await _adapter.ConnectAsync(_options.CommunicationTimeout).ConfigureAwait(false);
                 _logger.Trace<MqttClient>("Connection with server established.");
 
-                await StartReceivingPacketsAsync(_cancellationTokenSource.Token).ConfigureAwait(false);
+                await StartReceivingPacketsAsync().ConfigureAwait(false);
-                var connectResponse = await AuthenticateAsync(options.WillMessage).ConfigureAwait(false);
 
+                var connectResponse = await AuthenticateAsync(options.WillMessage).ConfigureAwait(false);
                 _logger.Trace<MqttClient>("MQTT connection with server established.");
 
+                _sendTracker.Restart();
+
                 if (_options.KeepAlivePeriod != TimeSpan.Zero)
                 {
-                    StartSendingKeepAliveMessages(_cancellationTokenSource.Token);
+                    StartSendingKeepAliveMessages();
                 }
 
                 IsConnected = true;
@@ -77,7 +82,8 @@ namespace MQTTnet.Core.Client
             catch (Exception exception)
             {
                 _logger.Error<MqttClient>(exception, "Error while connecting with server.");
-                await DisconnectInternalAsync().ConfigureAwait(false);
+                await DisconnectInternalAsync(exception).ConfigureAwait(false);
+
                 throw;
             }
         }
@@ -91,11 +97,14 @@ namespace MQTTnet.Core.Client
 
             try
             {
-                await SendAsync(new MqttDisconnectPacket()).ConfigureAwait(false);
+                if (!_cancellationTokenSource.IsCancellationRequested)
+                {
+                    await SendAsync(new MqttDisconnectPacket()).ConfigureAwait(false);
+                }
             }
             finally
             {
-                await DisconnectInternalAsync().ConfigureAwait(false);
+                await DisconnectInternalAsync(null).ConfigureAwait(false);
             }
         }
 
@@ -107,7 +116,7 @@ namespace MQTTnet.Core.Client
 
             var subscribePacket = new MqttSubscribePacket
             {
-                PacketIdentifier = GetNewPacketIdentifier(),
+                PacketIdentifier = _packetIdentifierProvider.GetNewPacketIdentifier(),
                 TopicFilters = topicFilters.ToList()
             };
 
@@ -129,11 +138,11 @@ namespace MQTTnet.Core.Client
 
             var unsubscribePacket = new MqttUnsubscribePacket
             {
-                PacketIdentifier = GetNewPacketIdentifier(),
+                PacketIdentifier = _packetIdentifierProvider.GetNewPacketIdentifier(),
                 TopicFilters = topicFilters.ToList()
             };
 
-            await SendAndReceiveAsync<MqttUnsubAckPacket>(unsubscribePacket);
+            await SendAndReceiveAsync<MqttUnsubAckPacket>(unsubscribePacket).ConfigureAwait(false);
         }
 
         public async Task PublishAsync(IEnumerable<MqttApplicationMessage> applicationMessages)
@@ -141,23 +150,23 @@ namespace MQTTnet.Core.Client
             ThrowIfNotConnected();
 
             var publishPackets = applicationMessages.Select(m => m.ToPublishPacket());
+            var packetGroups = publishPackets.GroupBy(p => p.QualityOfServiceLevel).OrderBy(g => g.Key);
 
-            foreach (var qosGroup in publishPackets.GroupBy(p => p.QualityOfServiceLevel))
+            foreach (var qosGroup in packetGroups)
             {
-                var qosPackets = qosGroup.ToArray();
                 switch (qosGroup.Key)
                 {
                     case MqttQualityOfServiceLevel.AtMostOnce:
                         {
                             // No packet identifier is used for QoS 0 [3.3.2.2 Packet Identifier]
-                            await _adapter.SendPacketsAsync(_options.CommunicationTimeout, _cancellationTokenSource.Token, qosPackets).ConfigureAwait(false);
+                            await SendAsync((MqttPublishPacket[])qosGroup.ToArray()).ConfigureAwait(false);
                             break;
                         }
                     case MqttQualityOfServiceLevel.AtLeastOnce:
                         {
-                            foreach (var publishPacket in qosPackets)
+                            foreach (var publishPacket in qosGroup)
                             {
-                                publishPacket.PacketIdentifier = GetNewPacketIdentifier();
+                                publishPacket.PacketIdentifier = _packetIdentifierProvider.GetNewPacketIdentifier();
                                 await SendAndReceiveAsync<MqttPubAckPacket>(publishPacket).ConfigureAwait(false);
                             }
 
@@ -165,11 +174,17 @@ namespace MQTTnet.Core.Client
                         }
                     case MqttQualityOfServiceLevel.ExactlyOnce:
                         {
-                            foreach (var publishPacket in qosPackets)
+                            foreach (var publishPacket in qosGroup)
                             {
-                                publishPacket.PacketIdentifier = GetNewPacketIdentifier();
+                                publishPacket.PacketIdentifier = _packetIdentifierProvider.GetNewPacketIdentifier();
+
                                 var pubRecPacket = await SendAndReceiveAsync<MqttPubRecPacket>(publishPacket).ConfigureAwait(false);
-                                await SendAndReceiveAsync<MqttPubCompPacket>(pubRecPacket.CreateResponse<MqttPubRelPacket>()).ConfigureAwait(false);
+                                var pubRelPacket = new MqttPubRelPacket
+                                {
+                                    PacketIdentifier = pubRecPacket.PacketIdentifier
+                                };
+
+                                await SendAndReceiveAsync<MqttPubCompPacket>(pubRelPacket).ConfigureAwait(false);
                             }
 
                             break;
@@ -182,6 +197,14 @@ namespace MQTTnet.Core.Client
             }
         }
 
+        public void Dispose()
+        {
+            _cancellationTokenSource?.Dispose();
+            _cancellationTokenSource = null;
+
+            _adapter?.Dispose();
+        }
+
         private async Task<MqttConnAckPacket> AuthenticateAsync(MqttApplicationMessage willApplicationMessage)
         {
             var connectPacket = new MqttConnectPacket
@@ -213,34 +236,50 @@ namespace MQTTnet.Core.Client
             if (IsConnected) throw new MqttProtocolViolationException(message);
         }
 
-        private async Task DisconnectInternalAsync()
+        private async Task DisconnectInternalAsync(Exception exception)
         {
+            await _disconnectLock.WaitAsync();
             var clientWasConnected = IsConnected;
-            IsConnected = false;
-
-            var cts = _cancellationTokenSource;
-            if (cts == null || cts.IsCancellationRequested)
-            {
-                return;
-            }
-
-            cts.Cancel(false);
-            cts.Dispose();
-            _cancellationTokenSource = null;
-
             try
             {
+                IsConnected = false;
+
+                if (_cancellationTokenSource == null || _cancellationTokenSource.IsCancellationRequested)
+                {
+                    return;
+                }
+
+                _cancellationTokenSource.Cancel(false);
+
+                if (_packetReceiverTask != null)
+                {
+                    Task.WaitAll(_packetReceiverTask);
+                }
+
+                if (_keepAliveMessageSenderTask != null)
+                {
+                    Task.WaitAll(_keepAliveMessageSenderTask);
+                }
+
                 await _adapter.DisconnectAsync(_options.CommunicationTimeout).ConfigureAwait(false);
-                _logger.Info<MqttClient>("Disconnected from adapter.");
+                _logger.Trace<MqttClient>("Disconnected from adapter.");
             }
-            catch (Exception exception)
+            catch (Exception adapterException)
             {
-                _logger.Warning<MqttClient>(exception, "Error while disconnecting from adapter.");
+                _logger.Warning<MqttClient>(adapterException, "Error while disconnecting from adapter.");
             }
             finally
             {
+                _adapter?.Dispose();
+                _adapter = null;
+
+                _cancellationTokenSource?.Dispose();
+                _cancellationTokenSource = null;
+
+                _disconnectLock.Release();
+                
                 _logger.Info<MqttClient>("Disconnected.");
-                Disconnected?.Invoke(this, new MqttClientDisconnectedEventArgs(clientWasConnected));
+                Disconnected?.Invoke(this, new MqttClientDisconnectedEventArgs(clientWasConnected, exception));
             }
         }
 
@@ -250,27 +289,27 @@ namespace MQTTnet.Core.Client
             {
                 _logger.Info<MqttClient>("Received <<< {0}", packet);
 
+                if (packet is MqttPublishPacket publishPacket)
+                {
+                    await ProcessReceivedPublishPacketAsync(publishPacket).ConfigureAwait(false);
+                    return;
+                }
+
                 if (packet is MqttPingReqPacket)
                 {
-                    await SendAsync(new MqttPingRespPacket());
+                    await SendAsync(new MqttPingRespPacket()).ConfigureAwait(false);
                     return;
                 }
 
                 if (packet is MqttDisconnectPacket)
                 {
-                    await DisconnectAsync();
+                    await DisconnectAsync().ConfigureAwait(false);
-                    return;
-                }
-
-                if (packet is MqttPublishPacket publishPacket)
-                {
-                    await ProcessReceivedPublishPacket(publishPacket);
                     return;
                 }
 
                 if (packet is MqttPubRelPacket pubRelPacket)
                 {
-                    await ProcessReceivedPubRelPacket(pubRelPacket);
+                    await ProcessReceivedPubRelPacket(pubRelPacket).ConfigureAwait(false);
                     return;
                 }
 
@@ -295,32 +334,30 @@ namespace MQTTnet.Core.Client
             }
         }
 
-        private async Task ProcessReceivedPublishPacket(MqttPublishPacket publishPacket)
+        private Task ProcessReceivedPublishPacketAsync(MqttPublishPacket publishPacket)
         {
+            if (_cancellationTokenSource.IsCancellationRequested)
+            {
+                return Task.FromResult(0);
+            }
+
             if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtMostOnce)
             {
                 FireApplicationMessageReceivedEvent(publishPacket);
-                return;
+                return Task.FromResult(0);
             }
 
             if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtLeastOnce)
             {
                 FireApplicationMessageReceivedEvent(publishPacket);
-                await SendAsync(new MqttPubAckPacket { PacketIdentifier = publishPacket.PacketIdentifier });
+                return SendAsync(new MqttPubAckPacket { PacketIdentifier = publishPacket.PacketIdentifier });
-                return;
             }
 
             if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.ExactlyOnce)
             {
                 // QoS 2 is implement as method "B" [4.3.3 QoS 2: Exactly once delivery]
-                lock (_unacknowledgedPublishPackets)
-                {
-                    _unacknowledgedPublishPackets.Add(publishPacket.PacketIdentifier);
-                }
-
                 FireApplicationMessageReceivedEvent(publishPacket);
-                await SendAsync(new MqttPubRecPacket { PacketIdentifier = publishPacket.PacketIdentifier });
+                return SendAsync(new MqttPubRecPacket { PacketIdentifier = publishPacket.PacketIdentifier });
-                return;
             }
 
             throw new MqttCommunicationException("Received a not supported QoS level.");
@@ -328,71 +365,77 @@ namespace MQTTnet.Core.Client
 
         private Task ProcessReceivedPubRelPacket(MqttPubRelPacket pubRelPacket)
         {
-            lock (_unacknowledgedPublishPackets)
+            var response = new MqttPubCompPacket
             {
-                _unacknowledgedPublishPackets.Remove(pubRelPacket.PacketIdentifier);
+                PacketIdentifier = pubRelPacket.PacketIdentifier
-            }
+            };
 
-            return SendAsync(pubRelPacket.CreateResponse<MqttPubCompPacket>());
+            return SendAsync(response);
         }
 
-        private Task SendAsync(MqttBasePacket packet)
+        private Task SendAsync(params MqttBasePacket[] packets)
         {
-            return _adapter.SendPacketsAsync(_options.CommunicationTimeout, _cancellationTokenSource.Token, packet);
+            _sendTracker.Restart();
+            return _adapter.SendPacketsAsync(_options.CommunicationTimeout, _cancellationTokenSource.Token, packets);
         }
 
         private async Task<TResponsePacket> SendAndReceiveAsync<TResponsePacket>(MqttBasePacket requestPacket) where TResponsePacket : MqttBasePacket
         {
-            var packetAwaiter = _packetDispatcher.WaitForPacketAsync(requestPacket, typeof(TResponsePacket), _options.CommunicationTimeout);
+            ushort? identifier = null;
-            await _adapter.SendPacketsAsync(_options.CommunicationTimeout, _cancellationTokenSource.Token, requestPacket).ConfigureAwait(false);
+            if (requestPacket is IMqttPacketWithIdentifier requestPacketWithIdentifier)
+            {
+                identifier = requestPacketWithIdentifier.PacketIdentifier;
+            }
+
+            var packetAwaiter = _packetDispatcher.WaitForPacketAsync(typeof(TResponsePacket), identifier, _options.CommunicationTimeout);
+            await SendAsync(requestPacket).ConfigureAwait(false);
+
             return (TResponsePacket)await packetAwaiter.ConfigureAwait(false);
         }
 
-        private ushort GetNewPacketIdentifier()
+        private async Task SendKeepAliveMessagesAsync()
-        {
-            return (ushort)Interlocked.Increment(ref _latestPacketIdentifier);
-        }
-
-        private async Task SendKeepAliveMessagesAsync(CancellationToken cancellationToken)
         {
             _logger.Info<MqttClient>("Start sending keep alive packets.");
 
             try
             {
-                while (!cancellationToken.IsCancellationRequested)
+                while (!_cancellationTokenSource.Token.IsCancellationRequested)
                 {
-                    await Task.Delay(_options.KeepAlivePeriod, cancellationToken).ConfigureAwait(false);
+                    var keepAliveSendInterval = TimeSpan.FromSeconds(_options.KeepAlivePeriod.TotalSeconds * 0.75);
-                    if (cancellationToken.IsCancellationRequested)
+                    if (_options.KeepAliveSendInterval.HasValue)
                     {
-                        return;
+                        keepAliveSendInterval = _options.KeepAliveSendInterval.Value;
                     }
 
-                    await SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket()).ConfigureAwait(false);
+                    if (_sendTracker.Elapsed > keepAliveSendInterval)
+                    {
+                        await SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket()).ConfigureAwait(false);
+                    }
+
+                    await Task.Delay(keepAliveSendInterval, _cancellationTokenSource.Token).ConfigureAwait(false);
                 }
             }
             catch (OperationCanceledException)
             {
-                if (cancellationToken.IsCancellationRequested)
-                {
-                    return;
-                }
-
-                await DisconnectInternalAsync().ConfigureAwait(false);
-            }
-            catch (MqttCommunicationException exception)
-            {
-                if (cancellationToken.IsCancellationRequested)
-                {
-                    return;
-                }
-
-                _logger.Warning<MqttClient>(exception, "MQTT communication exception while sending/receiving keep alive packets.");
-                await DisconnectInternalAsync().ConfigureAwait(false);
             }
             catch (Exception exception)
             {
-                _logger.Warning<MqttClient>(exception, "Unhandled exception while sending/receiving keep alive packets.");
+                if (_cancellationTokenSource.Token.IsCancellationRequested)
-                await DisconnectInternalAsync().ConfigureAwait(false);
+                {
+                    return;
+                }
+
+                if (exception is MqttCommunicationException)
+                {
+                    _logger.Warning<MqttClient>(exception, "MQTT communication exception while sending/receiving keep alive packets.");
+                }
+                else
+                {
+                    _logger.Warning<MqttClient>(exception, "Unhandled exception while sending/receiving keep alive packets.");
+
+                }
+
+                await DisconnectInternalAsync(exception).ConfigureAwait(false);
             }
             finally
             {
@@ -400,49 +443,47 @@ namespace MQTTnet.Core.Client
             }
         }
 
-        private async Task ReceivePacketsAsync(CancellationToken cancellationToken)
+        private async Task ReceivePacketsAsync()
         {
             _logger.Info<MqttClient>("Start receiving packets.");
 
             try
             {
-                while (!cancellationToken.IsCancellationRequested)
+                while (!_cancellationTokenSource.Token.IsCancellationRequested)
                 {
                     _isReceivingPackets = true;
 
-                    var packet = await _adapter.ReceivePacketAsync(TimeSpan.Zero, cancellationToken).ConfigureAwait(false);
+                    var packet = await _adapter.ReceivePacketAsync(TimeSpan.Zero, _cancellationTokenSource.Token).ConfigureAwait(false);
 
-                    if (cancellationToken.IsCancellationRequested)
+                    if (_cancellationTokenSource.Token.IsCancellationRequested)
                     {
                         return;
                     }
 
-                    StartProcessReceivedPacket(packet, cancellationToken);
+                    StartProcessReceivedPacket(packet);
                 }
             }
             catch (OperationCanceledException)
             {
-                if (cancellationToken.IsCancellationRequested)
-                {
-                    return;
-                }
-
-                await DisconnectInternalAsync().ConfigureAwait(false);
-            }
-            catch (MqttCommunicationException exception)
-            {
-                if (cancellationToken.IsCancellationRequested)
-                {
-                    return;
-                }
-
-                _logger.Warning<MqttClient>(exception, "MQTT communication exception while receiving packets.");
-                await DisconnectInternalAsync().ConfigureAwait(false);
             }
             catch (Exception exception)
             {
-                _logger.Error<MqttClient>(exception, "Unhandled exception while receiving packets.");
+                if (_cancellationTokenSource.IsCancellationRequested)
-                await DisconnectInternalAsync().ConfigureAwait(false);
+                {
+                    return;
+                }
+
+                if (exception is MqttCommunicationException)
+                {
+                    _logger.Warning<MqttClient>(exception, "MQTT communication exception while receiving packets.");
+                }
+                else
+                {
+                    _logger.Error<MqttClient>(exception, "Unhandled exception while receiving packets.");
+
+                }
+
+                await DisconnectInternalAsync(exception).ConfigureAwait(false);
             }
             finally
             {
@@ -450,38 +491,26 @@ namespace MQTTnet.Core.Client
             }
         }
 
-        private void StartProcessReceivedPacket(MqttBasePacket packet, CancellationToken cancellationToken)
+        private void StartProcessReceivedPacket(MqttBasePacket packet)
         {
-#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
+            Task.Run(() => ProcessReceivedPacketAsync(packet), _cancellationTokenSource.Token);
-            Task.Run(
-                () => ProcessReceivedPacketAsync(packet),
-                cancellationToken).ConfigureAwait(false);
-#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
         }
 
-        private async Task StartReceivingPacketsAsync(CancellationToken cancellationToken)
+        private async Task StartReceivingPacketsAsync()
         {
             _isReceivingPackets = false;
 
-#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
+            _packetReceiverTask = Task.Run(ReceivePacketsAsync, _cancellationTokenSource.Token);
-            Task.Run(
-                async () => await ReceivePacketsAsync(cancellationToken),
-                cancellationToken).ConfigureAwait(false);
-#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
 
-            while (!_isReceivingPackets && !cancellationToken.IsCancellationRequested)
+            while (!_isReceivingPackets && !_cancellationTokenSource.Token.IsCancellationRequested)
             {
-                await Task.Delay(TimeSpan.FromMilliseconds(100), cancellationToken).ConfigureAwait(false);
+                await Task.Delay(TimeSpan.FromMilliseconds(100), _cancellationTokenSource.Token).ConfigureAwait(false);
             }
         }
 
-        private void StartSendingKeepAliveMessages(CancellationToken cancellationToken)
+        private void StartSendingKeepAliveMessages()
         {
-#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
+            _keepAliveMessageSenderTask = Task.Run(SendKeepAliveMessagesAsync, _cancellationTokenSource.Token);
-            Task.Run(
-                async () => await SendKeepAliveMessagesAsync(cancellationToken), 
-                cancellationToken).ConfigureAwait(false);
-#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
         }
     }
 }

Frameworks/MQTTnet.NetStandard/Client/MqttClientConnectResult.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttClientConnectResult
     {

Frameworks/MQTTnet.NetStandard/Client/MqttClientConnectedEventArgs.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttClientConnectedEventArgs : EventArgs
     {

Frameworks/MQTTnet.NetStandard/Client/MqttClientCredentials.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttClientCredentials : IMqttClientCredentials
     {

Frameworks/MQTTnet.NetStandard/Client/MqttClientDisconnectedEventArgs.cs

@@ -1,14 +1,17 @@
 using System;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttClientDisconnectedEventArgs : EventArgs
     {
-        public MqttClientDisconnectedEventArgs(bool clientWasConnected)
+        public MqttClientDisconnectedEventArgs(bool clientWasConnected, Exception exception)
         {
             ClientWasConnected = clientWasConnected;
+            Exception = exception;
         }
 
         public bool ClientWasConnected { get; }
+
+        public Exception Exception { get; }
     }
 }

Frameworks/MQTTnet.NetStandard/Client/MqttClientExtensions.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Client
+{
+    public static class MqttClientExtensions
+    {
+        public static Task<IList<MqttSubscribeResult>> SubscribeAsync(this IMqttClient client, params TopicFilter[] topicFilters)
+        {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (topicFilters == null) throw new ArgumentNullException(nameof(topicFilters));
+
+            return client.SubscribeAsync(topicFilters.ToList());
+        }
+
+        public static Task<IList<MqttSubscribeResult>> SubscribeAsync(this IMqttClient client, string topic, MqttQualityOfServiceLevel qualityOfServiceLevel)
+        {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
+            return client.SubscribeAsync(new TopicFilterBuilder().WithTopic(topic).WithQualityOfServiceLevel(qualityOfServiceLevel).Build());
+        }
+
+        public static Task<IList<MqttSubscribeResult>> SubscribeAsync(this IMqttClient client, string topic)
+        {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
+            return client.SubscribeAsync(new TopicFilterBuilder().WithTopic(topic).Build());
+        }
+
+        public static Task UnsubscribeAsync(this IMqttClient client, params string[] topicFilters)
+        {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (topicFilters == null) throw new ArgumentNullException(nameof(topicFilters));
+
+            return client.UnsubscribeAsync(topicFilters.ToList());
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/Client/MqttClientOptions.cs

@@ -1,7 +1,7 @@
 using System;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Serializer;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttClientOptions : IMqttClientOptions
     {
@@ -13,7 +13,9 @@ namespace MQTTnet.Core.Client
 
         public IMqttClientCredentials Credentials { get; set; } = new MqttClientCredentials();
 
-        public TimeSpan KeepAlivePeriod { get; set; } = TimeSpan.FromSeconds(5);
+        public TimeSpan KeepAlivePeriod { get; set; } = TimeSpan.FromSeconds(15);
+
+        public TimeSpan? KeepAliveSendInterval { get; set; }
 
         public TimeSpan CommunicationTimeout { get; set; } = TimeSpan.FromSeconds(10);
 

Frameworks/MQTTnet.NetStandard/Client/MqttClientOptionsBuilder.cs

@@ -1,8 +1,8 @@
 using System;
 using System.Linq;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Serializer;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttClientOptionsBuilder
     {
@@ -119,11 +119,11 @@ namespace MQTTnet.Core.Client
 
                 if (_tcpOptions != null)
                 {
-                    _options.ChannelOptions = _tcpOptions;
+                    _tcpOptions.TlsOptions = _tlsOptions;
                 }
-                else
+                else if (_webSocketOptions != null)
                 {
-                    _options.ChannelOptions = _webSocketOptions;
+                    _webSocketOptions.TlsOptions = _tlsOptions;
                 }
             }
 

Frameworks/MQTTnet.NetStandard/Client/MqttClientTcpOptions.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttClientTcpOptions : IMqttClientChannelOptions
     {
@@ -6,6 +6,8 @@
 
         public int? Port { get; set; }
 
+        public int BufferSize { get; set; } = 20 * 4096;
+
         public MqttClientTlsOptions TlsOptions { get; set; } = new MqttClientTlsOptions();
     }
 }

Frameworks/MQTTnet.NetStandard/Client/MqttClientTcpOptionsExtensions.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public static class MqttClientTcpOptionsExtensions
     {

Frameworks/MQTTnet.NetStandard/Client/MqttClientTlsOptions.cs

@@ -1,6 +1,6 @@
 using System.Collections.Generic;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttClientTlsOptions
     {

Frameworks/MQTTnet.NetStandard/Client/MqttClientWebSocketOptions.cs

@@ -1,7 +1,7 @@
 using System.Collections.Generic;
 using System.Net;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttClientWebSocketOptions : IMqttClientChannelOptions
     {
@@ -9,7 +9,7 @@ namespace MQTTnet.Core.Client
 
         public IDictionary<string, string> RequestHeaders { get; set; }
 
-        public ICollection<string> SubProtocols { get; set; }
+        public ICollection<string> SubProtocols { get; set; } = new List<string> { "mqtt" };
 
         public CookieContainer CookieContainer { get; set; }
 

Frameworks/MQTTnet.NetStandard/Client/MqttPacketDispatcher.cs

@@ -0,0 +1,97 @@
+using System;
+using System.Collections.Concurrent;
+using System.Threading.Tasks;
+using MQTTnet.Diagnostics;
+using MQTTnet.Exceptions;
+using MQTTnet.Internal;
+using MQTTnet.Packets;
+
+namespace MQTTnet.Client
+{
+    public class MqttPacketDispatcher
+    {
+        private readonly ConcurrentDictionary<Type, ConcurrentDictionary<ushort, TaskCompletionSource<MqttBasePacket>>> _awaiters = new ConcurrentDictionary<Type, ConcurrentDictionary<ushort, TaskCompletionSource<MqttBasePacket>>>();
+        private readonly IMqttNetLogger _logger;
+
+        public MqttPacketDispatcher(IMqttNetLogger logger)
+        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public async Task<MqttBasePacket> WaitForPacketAsync(Type responseType, ushort? identifier, TimeSpan timeout)
+        {
+            var packetAwaiter = AddPacketAwaiter(responseType, identifier);
+            try
+            {
+                return await packetAwaiter.Task.TimeoutAfter(timeout).ConfigureAwait(false);
+            }
+            catch (MqttCommunicationTimedOutException)
+            {
+                _logger.Warning<MqttPacketDispatcher>("Timeout while waiting for packet of type '{0}'.", responseType.Name);
+                throw;
+            }
+            finally
+            {
+                RemovePacketAwaiter(responseType, identifier);
+            }
+        }
+
+        public void Dispatch(MqttBasePacket packet)
+        {
+            if (packet == null) throw new ArgumentNullException(nameof(packet));
+
+            var type = packet.GetType();
+
+            if (_awaiters.TryGetValue(type, out var byId))
+            {
+                ushort? identifier = 0;
+                if (packet is IMqttPacketWithIdentifier packetWithIdentifier)
+                {
+                    identifier = packetWithIdentifier.PacketIdentifier;
+                }
+
+                if (byId.TryRemove(identifier.Value, out var tcs))
+                {
+                    tcs.TrySetResult(packet);
+                    return;
+                }
+            }
+
+            throw new InvalidOperationException($"Packet of type '{type.Name}' not handled or dispatched.");
+        }
+
+        public void Reset()
+        {
+            _awaiters.Clear();
+        }
+
+        private TaskCompletionSource<MqttBasePacket> AddPacketAwaiter(Type responseType, ushort? identifier)
+        {
+            var tcs = new TaskCompletionSource<MqttBasePacket>();
+
+            if (!identifier.HasValue)
+            {
+                identifier = 0;
+            }
+
+            var byId = _awaiters.GetOrAdd(responseType, key => new ConcurrentDictionary<ushort, TaskCompletionSource<MqttBasePacket>>());
+            if (!byId.TryAdd(identifier.Value, tcs))
+            {
+                throw new InvalidOperationException($"The packet dispatcher already has an awaiter for packet of type '{responseType}' with identifier {identifier}.");
+            }
+
+            return tcs;
+        }
+
+        private void RemovePacketAwaiter(Type responseType, ushort? identifier)
+        {
+            if (!identifier.HasValue)
+            {
+                identifier = 0;
+            }
+
+            var byId = _awaiters.GetOrAdd(responseType, key => new ConcurrentDictionary<ushort, TaskCompletionSource<MqttBasePacket>>());
+            byId.TryRemove(identifier.Value, out var _);
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/Client/MqttPacketIdentifierProvider.cs

@@ -0,0 +1,32 @@
+namespace MQTTnet.Client
+{
+    public class MqttPacketIdentifierProvider
+    {
+        private readonly object _syncRoot = new object();
+        private ushort _value;
+
+        public void Reset()
+        {
+            lock (_syncRoot)
+            {
+                _value = 0;
+            }
+        }
+
+        public ushort GetNewPacketIdentifier()
+        {
+            lock (_syncRoot)
+            {
+                _value++;
+
+                if (_value == 0)
+                {
+                    // As per official MQTT documentation the package identifier should never be 0.
+                    _value = 1;
+                }
+
+                return _value;
+            }
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/Client/MqttSubscribeResult.cs

@@ -1,7 +1,6 @@
-using MQTTnet.Core.Packets;
+using MQTTnet.Protocol;
-using MQTTnet.Core.Protocol;
 
-namespace MQTTnet.Core.Client
+namespace MQTTnet.Client
 {
     public class MqttSubscribeResult
     {

Frameworks/MQTTnet.NetStandard/Diagnostics/IMqttNetLogger.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace MQTTnet.Core.Diagnostics
+namespace MQTTnet.Diagnostics
 {
     public interface IMqttNetLogger
     {

Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetConsoleLogger.cs

@@ -1,50 +0,0 @@
-using System;
-using System.Text;
-using MQTTnet.Core.Diagnostics;
-
-namespace MQTTnet.Diagnostics
-{
-    public static class MqttNetConsoleLogger
-    {
-        private static readonly object Lock = new object();
-
-        public static void ForwardToConsole()
-        {
-            MqttNetGlobalLog.LogMessagePublished -= PrintToConsole;
-            MqttNetGlobalLog.LogMessagePublished += PrintToConsole;
-        }
-
-        private static void PrintToConsole(object sender, MqttNetLogMessagePublishedEventArgs e)
-        {
-            var output = new StringBuilder();
-            output.AppendLine($">> [{e.TraceMessage.Timestamp:O}] [{e.TraceMessage.ThreadId}] [{e.TraceMessage.Source}] [{e.TraceMessage.Level}]: {e.TraceMessage.Message}");
-            if (e.TraceMessage.Exception != null)
-            {
-                output.AppendLine(e.TraceMessage.Exception.ToString());
-            }
-
-            lock (Lock)
-            {
-                var backupColor = Console.ForegroundColor;
-                switch (e.TraceMessage.Level)
-                {
-                    case MqttNetLogLevel.Error:
-                        Console.ForegroundColor = ConsoleColor.Red;
-                        break;
-                    case MqttNetLogLevel.Warning:
-                        Console.ForegroundColor = ConsoleColor.Yellow;
-                        break;
-                    case MqttNetLogLevel.Info:
-                        Console.ForegroundColor = ConsoleColor.Green;
-                        break;
-                    case MqttNetLogLevel.Verbose:
-                        Console.ForegroundColor = ConsoleColor.Gray;
-                        break;
-                }
-
-                Console.Write(output);
-                Console.ForegroundColor = backupColor;
-            }
-        }
-    }
-}

Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetGlobalLogger.cs

@@ -1,8 +1,8 @@
 using System;
 
-namespace MQTTnet.Core.Diagnostics
+namespace MQTTnet.Diagnostics
 {
-    public static class MqttNetGlobalLog
+    public static class MqttNetGlobalLogger
     {
         public static event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 

Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogLevel.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Diagnostics
+namespace MQTTnet.Diagnostics
 {
     public enum MqttNetLogLevel
     {

Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogMessage.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace MQTTnet.Core.Diagnostics
+namespace MQTTnet.Diagnostics
 {
     public sealed class MqttNetLogMessage
     {
@@ -28,5 +28,16 @@ namespace MQTTnet.Core.Diagnostics
         public string Message { get; }
 
         public Exception Exception { get; }
+
+        public override string ToString()
+        {
+            var result = $"[{Timestamp:O}] [{LogId}] [{ThreadId}] [{Source}] [{Level}]: {Message}";
+            if (Exception != null)
+            {
+                result += Environment.NewLine + Exception;
+            }
+
+            return result;
+        }
     }
 }

Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogMessagePublishedEventArgs.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace MQTTnet.Core.Diagnostics
+namespace MQTTnet.Diagnostics
 {
     public sealed class MqttNetLogMessagePublishedEventArgs : EventArgs
     {

Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogger.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace MQTTnet.Core.Diagnostics
+namespace MQTTnet.Diagnostics
 {
     public class MqttNetLogger : IMqttNetLogger
     {
@@ -10,7 +10,7 @@ namespace MQTTnet.Core.Diagnostics
         {
             _logId = logId;
         }
-        
+
         public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
 
         public void Trace<TSource>(string message, params object[] parameters)
@@ -46,7 +46,7 @@ namespace MQTTnet.Core.Diagnostics
         private void Publish<TSource>(MqttNetLogLevel logLevel, Exception exception, string message, object[] parameters)
         {
             var hasLocalListeners = LogMessagePublished != null;
-            var hasGlobalListeners = MqttNetGlobalLog.HasListeners;
+            var hasGlobalListeners = MqttNetGlobalLogger.HasListeners;
 
             if (!hasLocalListeners && !hasGlobalListeners)
             {
@@ -62,7 +62,7 @@ namespace MQTTnet.Core.Diagnostics
 
             if (hasGlobalListeners)
             {
-                MqttNetGlobalLog.Publish(traceMessage);
+                MqttNetGlobalLogger.Publish(traceMessage);
             }
 
             if (hasLocalListeners)

Frameworks/MQTTnet.NetStandard/Diagnostics/TargetFrameworkInfoProvider.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet
+namespace MQTTnet.Diagnostics
 {
     public static class TargetFrameworkInfoProvider
     {

Frameworks/MQTTnet.NetStandard/Exceptions/MqttCommunicationException.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace MQTTnet.Core.Exceptions
+namespace MQTTnet.Exceptions
 {
     public class MqttCommunicationException : Exception
     {

Frameworks/MQTTnet.NetStandard/Exceptions/MqttCommunicationTimedOutException.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Exceptions
+namespace MQTTnet.Exceptions
 {
     public sealed class MqttCommunicationTimedOutException : MqttCommunicationException
     {

Frameworks/MQTTnet.NetStandard/Exceptions/MqttProtocolViolationException.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace MQTTnet.Core.Exceptions
+namespace MQTTnet.Exceptions
 {
     public sealed class MqttProtocolViolationException : Exception
     {

Frameworks/MQTTnet.NetStandard/IApplicationMessagePublisher.cs

@@ -1,7 +1,7 @@
 using System.Collections.Generic;
 using System.Threading.Tasks;
 
-namespace MQTTnet.Core
+namespace MQTTnet
 {
     public interface IApplicationMessagePublisher
     {

Frameworks/MQTTnet.NetStandard/IApplicationMessageReceiver.cs

@@ -1,7 +1,6 @@
 using System;
-using MQTTnet.Core.Client;
 
-namespace MQTTnet.Core
+namespace MQTTnet
 {
     public interface IApplicationMessageReceiver
     {

Frameworks/MQTTnet.NetStandard/Implementations/MqttClientAdapterFactory.cs

@@ -1,8 +1,8 @@
 using System;
-using MQTTnet.Core.Adapter;
+using MQTTnet.Adapter;
-using MQTTnet.Core.Client;
+using MQTTnet.Client;
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Diagnostics;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Serializer;
 
 namespace MQTTnet.Implementations
 {

Frameworks/MQTTnet.NetStandard/Implementations/MqttServerAdapter.Uwp.cs

@@ -1,11 +1,11 @@
 #if WINDOWS_UWP
 using System;
 using System.Threading.Tasks;
-using MQTTnet.Core.Adapter;
-using MQTTnet.Core.Server;
 using Windows.Networking.Sockets;
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Adapter;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Diagnostics;
+using MQTTnet.Serializer;
+using MQTTnet.Server;
 
 namespace MQTTnet.Implementations
 {
@@ -21,7 +21,7 @@ namespace MQTTnet.Implementations
 
         public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
 
-        public async Task StartAsync(MqttServerOptions options)
+        public async Task StartAsync(IMqttServerOptions options)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 

Frameworks/MQTTnet.NetStandard/Implementations/MqttServerAdapter.cs

@@ -7,10 +7,10 @@ using System.Security.Authentication;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Core.Adapter;
+using MQTTnet.Adapter;
-using MQTTnet.Core.Server;
+using MQTTnet.Diagnostics;
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Serializer;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Server;
 
 namespace MQTTnet.Implementations
 {
@@ -30,7 +30,7 @@ namespace MQTTnet.Implementations
 
         public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
 
-        public Task StartAsync(MqttServerOptions options)
+        public Task StartAsync(IMqttServerOptions options)
         {
             if (_cancellationTokenSource != null) throw new InvalidOperationException("Server is already started.");
 
@@ -39,10 +39,10 @@ namespace MQTTnet.Implementations
             if (options.DefaultEndpointOptions.IsEnabled)
             {
                 _defaultEndpointSocket = new Socket(SocketType.Stream, ProtocolType.Tcp);
-                _defaultEndpointSocket.Bind(new IPEndPoint(IPAddress.Any, options.GetDefaultEndpointPort()));
+                _defaultEndpointSocket.Bind(new IPEndPoint(options.DefaultEndpointOptions.BoundIPAddress, options.GetDefaultEndpointPort()));
                 _defaultEndpointSocket.Listen(options.ConnectionBacklog);
 
-                Task.Run(() => AcceptDefaultEndpointConnectionsAsync(_cancellationTokenSource.Token), _cancellationTokenSource.Token);
+                Task.Run(async () => await AcceptDefaultEndpointConnectionsAsync(_cancellationTokenSource.Token).ConfigureAwait(false), _cancellationTokenSource.Token).ConfigureAwait(false);
             }
 
             if (options.TlsEndpointOptions.IsEnabled)
@@ -59,10 +59,10 @@ namespace MQTTnet.Implementations
                 }
 
                 _tlsEndpointSocket = new Socket(SocketType.Stream, ProtocolType.Tcp);
-                _tlsEndpointSocket.Bind(new IPEndPoint(IPAddress.Any, options.GetTlsEndpointPort()));
+                _tlsEndpointSocket.Bind(new IPEndPoint(options.TlsEndpointOptions.BoundIPAddress, options.GetTlsEndpointPort()));
                 _tlsEndpointSocket.Listen(options.ConnectionBacklog);
 
-                Task.Run(() => AcceptTlsEndpointConnectionsAsync(_cancellationTokenSource.Token), _cancellationTokenSource.Token);
+                Task.Run(async () => await AcceptTlsEndpointConnectionsAsync(_cancellationTokenSource.Token).ConfigureAwait(false), _cancellationTokenSource.Token).ConfigureAwait(false);
             }
 
             return Task.FromResult(0);
@@ -102,14 +102,22 @@ namespace MQTTnet.Implementations
 #else
                     var clientSocket = await _defaultEndpointSocket.AcceptAsync().ConfigureAwait(false);
 #endif
+
                     var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(clientSocket, null), new MqttPacketSerializer(), _logger);
                     ClientAccepted?.Invoke(this, new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
                 }
+                catch (ObjectDisposedException)
+                {
+                    // It can happen that the listener socket is accessed after the cancellation token is already set and the listener socket is disposed.
+                }
                 catch (Exception exception)
                 {
-                    _logger.Error<MqttServerAdapter>(exception, "Error while accepting connection at default endpoint.");
+                    if (exception is SocketException s && s.SocketErrorCode == SocketError.OperationAborted)
+                    {
+                        return;
+                    }
 
-                    //excessive CPU consumed if in endless loop of socket errors
+                    _logger.Error<MqttServerAdapter>(exception, "Error while accepting connection at default endpoint.");
                     await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);
                 }
             }
@@ -129,15 +137,22 @@ namespace MQTTnet.Implementations
 
                     var sslStream = new SslStream(new NetworkStream(clientSocket));
                     await sslStream.AuthenticateAsServerAsync(_tlsCertificate, false, SslProtocols.Tls12, false).ConfigureAwait(false);
-
+                    
                     var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(clientSocket, sslStream), new MqttPacketSerializer(), _logger);
                     ClientAccepted?.Invoke(this, new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
                 }
+                catch (ObjectDisposedException)
+                {
+                    // It can happen that the listener socket is accessed after the cancellation token is already set and the listener socket is disposed.
+                }
                 catch (Exception exception)
                 {
-                    _logger.Error<MqttServerAdapter>(exception, "Error while accepting connection at TLS endpoint.");
+                    if (exception is SocketException s && s.SocketErrorCode == SocketError.OperationAborted)
+                    {
+                        return;
+                    }
 
-                    //excessive CPU consumed if in endless loop of socket errors
+                    _logger.Error<MqttServerAdapter>(exception, "Error while accepting connection at TLS endpoint.");
                     await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);
                 }
             }

Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.Uwp.cs

@@ -8,19 +8,26 @@ using System.Threading.Tasks;
 using Windows.Networking;
 using Windows.Networking.Sockets;
 using Windows.Security.Cryptography.Certificates;
-using MQTTnet.Core.Channel;
+using MQTTnet.Channel;
-using MQTTnet.Core.Client;
+using MQTTnet.Client;
 
 namespace MQTTnet.Implementations
 {
-    public sealed class MqttTcpChannel : IMqttChannel, IDisposable
+    public sealed class MqttTcpChannel : IMqttChannel
     {
+        // ReSharper disable once MemberCanBePrivate.Global
+        // ReSharper disable once AutoPropertyCanBeMadeGetOnly.Global
+        public static int BufferSize { get; set; } = 4096 * 20; // Can be changed for fine tuning by library user.
+
+        private readonly int _bufferSize = BufferSize;
         private readonly MqttClientTcpOptions _options;
+
         private StreamSocket _socket;
 
         public MqttTcpChannel(MqttClientTcpOptions options)
         {
             _options = options ?? throw new ArgumentNullException(nameof(options));
+            _bufferSize = _options.BufferSize;
         }
 
         public MqttTcpChannel(StreamSocket socket)
@@ -69,20 +76,56 @@ namespace MQTTnet.Implementations
 
         public void Dispose()
         {
-            SendStream?.Dispose();
+            try
-            SendStream = null;
+            {
+                SendStream?.Dispose();
+            }
+            catch (ObjectDisposedException)
+            {
+            }
+            catch (NullReferenceException)
+            {
+            }
+            finally
+            {
+                SendStream = null;
+            }
 
-            ReceiveStream?.Dispose();
+            try
-            ReceiveStream = null;
+            {
+                ReceiveStream?.Dispose();
+            }
+            catch (ObjectDisposedException)
+            {
+            }
+            catch (NullReferenceException)
+            {
+            }
+            finally
+            {
+                ReceiveStream = null;
+            }
 
-            _socket?.Dispose();
+            try
-            _socket = null;
+            {
+                _socket?.Dispose();
+            }
+            catch (ObjectDisposedException)
+            {
+            }
+            catch (NullReferenceException)
+            {
+            }
+            finally
+            {
+                _socket = null;
+            }
         }
 
         private void CreateStreams()
         {
-            SendStream = _socket.OutputStream.AsStreamForWrite();
+            SendStream = _socket.OutputStream.AsStreamForWrite(_bufferSize);
-            ReceiveStream = _socket.InputStream.AsStreamForRead();
+            ReceiveStream = _socket.InputStream.AsStreamForRead(_bufferSize);
         }
 
         private static Certificate LoadCertificate(MqttClientTcpOptions options)

Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.cs

@@ -5,24 +5,27 @@ using System.Net.Sockets;
 using System.Security.Authentication;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading.Tasks;
-using MQTTnet.Core.Channel;
-using MQTTnet.Core.Client;
 using System.IO;
 using System.Linq;
+using MQTTnet.Channel;
+using MQTTnet.Client;
 
 namespace MQTTnet.Implementations
 {
-    public sealed class MqttTcpChannel : IMqttChannel, IDisposable
+    public sealed class MqttTcpChannel : IMqttChannel
     {
-        private readonly MqttClientTcpOptions _options;
-
-        //todo: this can be used with min dependency NetStandard1.6
 #if NET452 || NET461
         // ReSharper disable once MemberCanBePrivate.Global
         // ReSharper disable once AutoPropertyCanBeMadeGetOnly.Global
         public static int BufferSize { get; set; } = 4096 * 20; // Can be changed for fine tuning by library user.
+
+        private readonly int _bufferSize = BufferSize;
+#else
+        private readonly int _bufferSize = 0;
 #endif
 
+        private readonly MqttClientTcpOptions _options;
+
         private Socket _socket;
         private SslStream _sslStream;
 
@@ -32,6 +35,7 @@ namespace MQTTnet.Implementations
         public MqttTcpChannel(MqttClientTcpOptions options)
         {
             _options = options ?? throw new ArgumentNullException(nameof(options));
+            _bufferSize = options.BufferSize;
         }
 
         /// <summary>
@@ -43,7 +47,7 @@ namespace MQTTnet.Implementations
             _socket = socket ?? throw new ArgumentNullException(nameof(socket));
             _sslStream = sslStream;
 
-            CreateStreams(socket, sslStream);
+            CreateStreams();
         }
 
         public Stream SendStream { get; private set; }
@@ -58,7 +62,6 @@ namespace MQTTnet.Implementations
                 _socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
             }
 
-            //todo: else brach can be used with min dependency NET46
 #if NET452 || NET461
             await Task.Factory.FromAsync(_socket.BeginConnect, _socket.EndConnect, _options.Server, _options.GetPort(), null).ConfigureAwait(false);
 #else
@@ -68,10 +71,10 @@ namespace MQTTnet.Implementations
             if (_options.TlsOptions.UseTls)
             {
                 _sslStream = new SslStream(new NetworkStream(_socket, true), false, InternalUserCertificateValidationCallback);
-                await _sslStream.AuthenticateAsClientAsync(_options.Server, LoadCertificates(_options), SslProtocols.Tls12, _options.TlsOptions.IgnoreCertificateRevocationErrors).ConfigureAwait(false);
+                await _sslStream.AuthenticateAsClientAsync(_options.Server, LoadCertificates(), SslProtocols.Tls12, _options.TlsOptions.IgnoreCertificateRevocationErrors).ConfigureAwait(false);
             }
-
+            
-            CreateStreams(_socket, _sslStream);
+            CreateStreams();
         }
 
         public Task DisconnectAsync()
@@ -82,11 +85,70 @@ namespace MQTTnet.Implementations
 
         public void Dispose()
         {
-            _socket?.Dispose();
+            var oneStreamIsUsed = SendStream != null && ReceiveStream != null && ReferenceEquals(SendStream, ReceiveStream);
-            _socket = null;
 
-            _sslStream?.Dispose();
+            try
-            _sslStream = null;
+            {
+                SendStream?.Dispose();
+            }
+            catch (ObjectDisposedException)
+            {
+            }
+            catch (NullReferenceException)
+            {
+            }
+            finally
+            {
+                SendStream = null;
+            }
+
+            try
+            {
+                if (!oneStreamIsUsed)
+                {
+                    ReceiveStream?.Dispose();
+                }
+            }
+            catch (ObjectDisposedException)
+            {
+            }
+            catch (NullReferenceException)
+            {
+            }
+            finally
+            {
+                ReceiveStream = null;
+            }
+
+            try
+            {
+                _sslStream?.Dispose();
+            }
+            catch (ObjectDisposedException)
+            {
+            }
+            catch (NullReferenceException)
+            {
+            }
+            finally
+            {
+                _sslStream = null;
+            }
+
+            try
+            {
+                _socket?.Dispose();
+            }
+            catch (ObjectDisposedException)
+            {
+            }
+            catch (NullReferenceException)
+            {
+            }
+            finally
+            {
+                _socket = null;
+            }
         }
 
         private bool InternalUserCertificateValidationCallback(object sender, X509Certificate x509Certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
@@ -120,39 +182,42 @@ namespace MQTTnet.Implementations
             return _options.TlsOptions.AllowUntrustedCertificates;
         }
 
-        private static X509CertificateCollection LoadCertificates(MqttClientTcpOptions options)
+        private X509CertificateCollection LoadCertificates()
         {
             var certificates = new X509CertificateCollection();
-            if (options.TlsOptions.Certificates == null)
+            if (_options.TlsOptions.Certificates == null)
             {
                 return certificates;
             }
 
-            foreach (var certificate in options.TlsOptions.Certificates)
+            foreach (var certificate in _options.TlsOptions.Certificates)
             {
-                certificates.Add(new X509Certificate(certificate));
+                certificates.Add(new X509Certificate2(certificate));
             }
 
             return certificates;
         }
 
-        private void CreateStreams(Socket socket, Stream sslStream)
+        private void CreateStreams()
         {
-            var stream = sslStream ?? new NetworkStream(socket);
+            Stream stream;
-
+            if (_sslStream != null)
-            //cannot use this as default buffering prevents from receiving the first connect message
+            {
-            //need two streams otherwise read and write have to be synchronized
+                stream = _sslStream;
-
+            }
-            //todo: if branch can be used with min dependency NetStandard1.6
+            else
+            {
+                stream = new NetworkStream(_socket, true);
+            }
+            
 #if NET452 || NET461
-            SendStream = new BufferedStream(stream, BufferSize);
+            SendStream = new BufferedStream(stream, _bufferSize);
-            ReceiveStream = new BufferedStream(stream, BufferSize);
+            ReceiveStream = new BufferedStream(stream, _bufferSize);
 #else
             SendStream = stream;
             ReceiveStream = stream;
 #endif
         }
-
     }
 }
-#endif
+#endif

Frameworks/MQTTnet.NetStandard/Implementations/MqttWebSocketChannel.cs

@@ -1,11 +1,11 @@
-using MQTTnet.Core.Channel;
+using System;
-using MQTTnet.Core.Client;
-using System;
 using System.IO;
 using System.Net.WebSockets;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Channel;
+using MQTTnet.Client;
 
 namespace MQTTnet.Implementations
 {
@@ -96,8 +96,17 @@ namespace MQTTnet.Implementations
 
         public void Dispose()
         {
-            _webSocket?.Dispose();
+            try
-            _webSocket = null;
+            {
+                _webSocket?.Dispose();
+            }
+            catch (ObjectDisposedException)
+            {
+            }
+            finally
+            {
+                _webSocket = null;
+            }            
         }
     }
 }

Frameworks/MQTTnet.NetStandard/Implementations/WebSocketStream.cs

@@ -5,15 +5,15 @@ using System.Linq;
 using System.Net.WebSockets;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Core.Exceptions;
+using MQTTnet.Exceptions;
 
 namespace MQTTnet.Implementations
 {
     public class WebSocketStream : Stream
     {
-        private readonly WebSocket _webSocket;
+        private readonly byte[] _chunckBuffer = new byte[MqttWebSocketChannel.BufferSize];
-        private readonly byte[] _chunkBuffer = new byte[MqttWebSocketChannel.BufferSize];
         private readonly Queue<byte> _buffer = new Queue<byte>(MqttWebSocketChannel.BufferSize);
+        private readonly WebSocket _webSocket;
 
         public WebSocketStream(WebSocket webSocket)
         {
@@ -55,25 +55,28 @@ namespace MQTTnet.Implementations
             // Use existing date from buffer.
             while (count > 0 && _buffer.Any())
             {
-                buffer[offset++] = _buffer.Dequeue();
+                buffer[offset] = _buffer.Dequeue();
                 count--;
                 bytesRead++;
+                offset++;
             }
 
             if (count == 0)
             {
                 return bytesRead;
             }
-            
+
+            // Fetch new data if the buffer is not full.
             while (_webSocket.State == WebSocketState.Open)
             {
-                await FetchChunkAsync(cancellationToken);
+                await FetchChunkAsync(cancellationToken).ConfigureAwait(false);
 
                 while (count > 0 && _buffer.Any())
                 {
-                    buffer[offset++] = _buffer.Dequeue();
+                    buffer[offset] = _buffer.Dequeue();
                     count--;
                     bytesRead++;
+                    offset++;
                 }
 
                 if (count == 0)
@@ -111,19 +114,24 @@ namespace MQTTnet.Implementations
         }
 
         private async Task FetchChunkAsync(CancellationToken cancellationToken)
-        {
+        {   
-            var response = await _webSocket.ReceiveAsync(new ArraySegment<byte>(_chunkBuffer, 0, _chunkBuffer.Length), cancellationToken).ConfigureAwait(false);
+            var response = await _webSocket.ReceiveAsync(new ArraySegment<byte>(_chunckBuffer, 0, _chunckBuffer.Length), cancellationToken).ConfigureAwait(false);
-
-            for (var i = 0; i < response.Count; i++)
-            {
-                var @byte = _chunkBuffer[i];
-                _buffer.Enqueue(@byte);
-            }
 
             if (response.MessageType == WebSocketMessageType.Close)
             {
                 await _webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, cancellationToken).ConfigureAwait(false);
             }
+            else if (response.MessageType == WebSocketMessageType.Binary)
+            {
+                for (var i = 0; i < response.Count; i++)
+                {
+                    _buffer.Enqueue(_chunckBuffer[i]);
+                }
+            }
+            else if (response.MessageType == WebSocketMessageType.Text)
+            {
+                throw new MqttProtocolViolationException("WebSocket channel received TEXT message.");
+            }
         }
     }
 }

Frameworks/MQTTnet.NetStandard/Internal/MqttApplicationMessageExtensions.cs

@@ -1,6 +1,6 @@
-using MQTTnet.Core.Packets;
+using MQTTnet.Packets;
 
-namespace MQTTnet.Core.Internal
+namespace MQTTnet.Internal
 {
     internal static class MqttApplicationMessageExtensions
     {

Frameworks/MQTTnet.NetStandard/Internal/TaskExtensions.cs

@@ -1,21 +1,23 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Core.Exceptions;
+using MQTTnet.Exceptions;
 
-namespace MQTTnet.Core.Internal
+namespace MQTTnet.Internal
 {
     public static class TaskExtensions
     {
         public static async Task TimeoutAfter(this Task task, TimeSpan timeout)
         {
-            using (var cancellationTokenSource = new CancellationTokenSource())
+            if (task == null) throw new ArgumentNullException(nameof(task));
+
+            using (var timeoutCts = new CancellationTokenSource())
             {
                 try
                 {
-                    var timeoutTask = Task.Delay(timeout, cancellationTokenSource.Token);
+                    var timeoutTask = Task.Delay(timeout, timeoutCts.Token);
                     var finishedTask = await Task.WhenAny(timeoutTask, task).ConfigureAwait(false);
-
+                    
                     if (finishedTask == timeoutTask)
                     {
                         throw new MqttCommunicationTimedOutException();
@@ -28,23 +30,25 @@ namespace MQTTnet.Core.Internal
 
                     if (task.IsFaulted)
                     {
-                        throw new MqttCommunicationException(task.Exception.GetBaseException());
+                        throw new MqttCommunicationException(task.Exception?.GetBaseException());
                     }
                 }
                 finally
                 {
-                    cancellationTokenSource.Cancel();
+                    timeoutCts.Cancel();
                 }
             }
         }
 
         public static async Task<TResult> TimeoutAfter<TResult>(this Task<TResult> task, TimeSpan timeout)
         {
-            using (var cancellationTokenSource = new CancellationTokenSource())
+            if (task == null) throw new ArgumentNullException(nameof(task));
+
+            using (var timeoutCts = new CancellationTokenSource())
             {
                 try
                 {
-                    var timeoutTask = Task.Delay(timeout, cancellationTokenSource.Token);
+                    var timeoutTask = Task.Delay(timeout, timeoutCts.Token);
                     var finishedTask = await Task.WhenAny(timeoutTask, task).ConfigureAwait(false);
 
                     if (finishedTask == timeoutTask)
@@ -66,7 +70,7 @@ namespace MQTTnet.Core.Internal
                 }
                 finally
                 {
-                    cancellationTokenSource.Cancel();
+                    timeoutCts.Cancel();
                 }
             }
         }

Frameworks/MQTTnet.NetStandard/MQTTnet.Netstandard.csproj

@@ -1,19 +1,22 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard1.3;netstandard2.0;net452;net461;uap10.0</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">netstandard1.3;netstandard2.0;net452;net461;uap10.0</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' != 'Windows_NT' ">netstandard1.3;netstandard2.0</TargetFrameworks>
     <AssemblyName>MQTTnet</AssemblyName>
     <RootNamespace>MQTTnet</RootNamespace>
     <GeneratePackageOnBuild>False</GeneratePackageOnBuild>
     <DebugType>Full</DebugType>
-    <AssemblyVersion>2.5.3.0</AssemblyVersion>
+    <AssemblyVersion>0.0.0.0</AssemblyVersion>
-    <FileVersion>2.5.3.0</FileVersion>
+    <FileVersion>0.0.0.0</FileVersion>
     <Version>0.0.0.0</Version>
     <Company />
     <Product />
     <Description />
     <Authors />
     <PackageId />
+    <SignAssembly>false</SignAssembly>
+    <DelaySign>false</DelaySign>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(TargetFramework)' == 'uap10.0'">
@@ -25,17 +28,17 @@
     <TargetFrameworkIdentifier>.NETCore</TargetFrameworkIdentifier>
     <TargetFrameworkVersion>v5.0</TargetFrameworkVersion>
     <DefineConstants>$(DefineConstants);WINDOWS_UWP</DefineConstants>
+    <DefaultLanguage>en</DefaultLanguage>
     <LanguageTargets>$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets</LanguageTargets>
-    
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x86'" />
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" />
 
-  <ItemGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Release|netstandard1.3|AnyCPU'">
-    <ProjectReference Include="..\..\MQTTnet.Core\MQTTnet.Core.csproj" />
+    <DefineConstants>RELEASE;NETSTANDARD1_3</DefineConstants>
-  </ItemGroup>
+  </PropertyGroup>
 
   <ItemGroup Condition="'$(TargetFramework)'=='netstandard2.0'">
     <PackageReference Include="System.Net.Security" Version="4.3.2" />

Frameworks/MQTTnet.NetStandard/ManagedClient/ApplicationMessageProcessedEventArgs.cs

@@ -0,0 +1,19 @@
+using System;
+
+namespace MQTTnet.ManagedClient
+{
+    public class ApplicationMessageProcessedEventArgs : EventArgs
+    {
+        public ApplicationMessageProcessedEventArgs(MqttApplicationMessage applicationMessage, Exception exception)
+        {
+            ApplicationMessage = applicationMessage ?? throw new ArgumentNullException(nameof(applicationMessage));
+            Exception = exception;
+        }
+
+        public MqttApplicationMessage ApplicationMessage { get; }
+        public Exception Exception { get; }
+
+        public bool HasFailed => Exception != null;
+        public bool HasSucceeded => Exception == null;
+    }
+}

Frameworks/MQTTnet.NetStandard/ManagedClient/IManagedMqttClient.cs

@@ -1,21 +1,24 @@
 using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
-using MQTTnet.Core.Client;
+using MQTTnet.Client;
 
-namespace MQTTnet.Core.ManagedClient
+namespace MQTTnet.ManagedClient
 {
-    public interface IManagedMqttClient : IApplicationMessageReceiver, IApplicationMessagePublisher
+    public interface IManagedMqttClient : IApplicationMessageReceiver, IApplicationMessagePublisher, IDisposable
     {
+        bool IsStarted { get; }
         bool IsConnected { get; }
 
         event EventHandler<MqttClientConnectedEventArgs> Connected;
         event EventHandler<MqttClientDisconnectedEventArgs> Disconnected;
 
+        event EventHandler<ApplicationMessageProcessedEventArgs> ApplicationMessageProcessed;
+
         Task StartAsync(IManagedMqttClientOptions options);
         Task StopAsync();
 
         Task SubscribeAsync(IEnumerable<TopicFilter> topicFilters);
-        Task UnsubscribeAsync(IEnumerable<TopicFilter> topicFilters);
+        Task UnsubscribeAsync(IEnumerable<string> topics);
     }
 }

Frameworks/MQTTnet.NetStandard/ManagedClient/IManagedMqttClientOptions.cs

@@ -1,7 +1,7 @@
 using System;
-using MQTTnet.Core.Client;
+using MQTTnet.Client;
 
-namespace MQTTnet.Core.ManagedClient
+namespace MQTTnet.ManagedClient
 {
     public interface IManagedMqttClientOptions
     {

Frameworks/MQTTnet.NetStandard/ManagedClient/IManagedMqttClientStorage.cs

@@ -1,7 +1,7 @@
 using System.Collections.Generic;
 using System.Threading.Tasks;
 
-namespace MQTTnet.Core.ManagedClient
+namespace MQTTnet.ManagedClient
 {
     public interface IManagedMqttClientStorage
     {

Frameworks/MQTTnet.NetStandard/ManagedClient/ManagedMqttClient.cs

@@ -4,18 +4,19 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Core.Client;
+using MQTTnet.Client;
-using MQTTnet.Core.Diagnostics;
+using MQTTnet.Diagnostics;
-using MQTTnet.Core.Exceptions;
+using MQTTnet.Exceptions;
-using MQTTnet.Core.Protocol;
+using MQTTnet.Protocol;
 
-namespace MQTTnet.Core.ManagedClient
+namespace MQTTnet.ManagedClient
 {
     public class ManagedMqttClient : IManagedMqttClient
     {
-        private readonly ManagedMqttClientStorageManager _storageManager = new ManagedMqttClientStorageManager();
         private readonly BlockingCollection<MqttApplicationMessage> _messageQueue = new BlockingCollection<MqttApplicationMessage>();
-        private readonly HashSet<TopicFilter> _subscriptions = new HashSet<TopicFilter>();
+        private readonly Dictionary<string, MqttQualityOfServiceLevel> _subscriptions = new Dictionary<string, MqttQualityOfServiceLevel>();
+        private readonly SemaphoreSlim _subscriptionsSemaphore = new SemaphoreSlim(1, 1);
+        private readonly List<string> _unsubscriptions = new List<string>();
 
         private readonly IMqttClient _mqttClient;
         private readonly IMqttNetLogger _logger;
@@ -23,9 +24,11 @@ namespace MQTTnet.Core.ManagedClient
         private CancellationTokenSource _connectionCancellationToken;
         private CancellationTokenSource _publishingCancellationToken;
 
+        private ManagedMqttClientStorageManager _storageManager;
         private IManagedMqttClientOptions _options;
+
         private bool _subscriptionsNotPushed;
-        
+
         public ManagedMqttClient(IMqttClient mqttClient, IMqttNetLogger logger)
         {
             _logger = logger ?? throw new ArgumentNullException(nameof(logger));
@@ -37,10 +40,13 @@ namespace MQTTnet.Core.ManagedClient
         }
 
         public bool IsConnected => _mqttClient.IsConnected;
+        public bool IsStarted => _connectionCancellationToken != null;
 
         public event EventHandler<MqttClientConnectedEventArgs> Connected;
         public event EventHandler<MqttClientDisconnectedEventArgs> Disconnected;
         public event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
+        public event EventHandler<ApplicationMessageProcessedEventArgs> ApplicationMessageProcessed;
+        public event EventHandler SynchronizingSubscriptionsFailed;
 
         public async Task StartAsync(IManagedMqttClientOptions options)
         {
@@ -55,21 +61,17 @@ namespace MQTTnet.Core.ManagedClient
             if (_connectionCancellationToken != null) throw new InvalidOperationException("The managed client is already started.");
 
             _options = options;
-            await _storageManager.SetStorageAsync(_options.Storage).ConfigureAwait(false);
 
             if (_options.Storage != null)
             {
-                var loadedMessages = await _options.Storage.LoadQueuedMessagesAsync().ConfigureAwait(false);
+                _storageManager = new ManagedMqttClientStorageManager(_options.Storage);
-                foreach (var loadedMessage in loadedMessages)
+                await _storageManager.LoadQueuedMessagesAsync().ConfigureAwait(false);
-                {
-                    _messageQueue.Add(loadedMessage);    
-                }
             }
 
             _connectionCancellationToken = new CancellationTokenSource();
-            
+
 #pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
-            Task.Run(async () => await MaintainConnectionAsync(_connectionCancellationToken.Token), _connectionCancellationToken.Token).ConfigureAwait(false);
+            Task.Run(async () => await MaintainConnectionAsync(_connectionCancellationToken.Token).ConfigureAwait(false), _connectionCancellationToken.Token).ConfigureAwait(false);
 #pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
 
             _logger.Info<ManagedMqttClient>("Started");
@@ -77,11 +79,8 @@ namespace MQTTnet.Core.ManagedClient
 
         public Task StopAsync()
         {
-            _connectionCancellationToken?.Cancel(false);
+            StopPublishing();
-            _connectionCancellationToken = null;
+            StopMaintainingConnection();
-
-            _publishingCancellationToken?.Cancel(false);
-            _publishingCancellationToken = null;
 
             while (_messageQueue.Any())
             {
@@ -97,43 +96,60 @@ namespace MQTTnet.Core.ManagedClient
 
             foreach (var applicationMessage in applicationMessages)
             {
-                await _storageManager.AddAsync(applicationMessage).ConfigureAwait(false);
+                if (_storageManager != null)
+                {
+                    await _storageManager.AddAsync(applicationMessage).ConfigureAwait(false);
+                }
+
                 _messageQueue.Add(applicationMessage);
             }
         }
 
-        public Task SubscribeAsync(IEnumerable<TopicFilter> topicFilters)
+        public async Task SubscribeAsync(IEnumerable<TopicFilter> topicFilters)
         {
             if (topicFilters == null) throw new ArgumentNullException(nameof(topicFilters));
 
-            lock (_subscriptions)
+            await _subscriptionsSemaphore.WaitAsync().ConfigureAwait(false);
+            try
             {
                 foreach (var topicFilter in topicFilters)
                 {
-                    if (_subscriptions.Add(topicFilter))
+                    _subscriptions[topicFilter.Topic] = topicFilter.QualityOfServiceLevel;
-                    {
+                    _subscriptionsNotPushed = true;
-                        _subscriptionsNotPushed = true;
-                    }
                 }
             }
-
+            finally
-            return Task.FromResult(0);
+            {
+                _subscriptionsSemaphore.Release();
+            }
         }
 
-        public Task UnsubscribeAsync(IEnumerable<TopicFilter> topicFilters)
+        public async Task UnsubscribeAsync(IEnumerable<string> topics)
         {
-            lock (_subscriptions)
+            await _subscriptionsSemaphore.WaitAsync().ConfigureAwait(false);
+            try
             {
-                foreach (var topicFilter in topicFilters)
+                foreach (var topic in topics)
                 {
-                    if (_subscriptions.Remove(topicFilter))
+                    if (_subscriptions.Remove(topic))
                     {
+                        _unsubscriptions.Add(topic);
                         _subscriptionsNotPushed = true;
                     }
                 }
             }
+            finally
+            {
+                _subscriptionsSemaphore.Release();
+            }
+        }
 
-            return Task.FromResult(0);
+        public void Dispose()
+        {
+            _messageQueue?.Dispose();
+            _subscriptionsSemaphore?.Dispose();
+            _connectionCancellationToken?.Dispose();
+            _publishingCancellationToken?.Dispose();
         }
 
         private async Task MaintainConnectionAsync(CancellationToken cancellationToken)
@@ -142,33 +158,48 @@ namespace MQTTnet.Core.ManagedClient
             {
                 while (!cancellationToken.IsCancellationRequested)
                 {
-                    var connectionState = await ReconnectIfRequiredAsync().ConfigureAwait(false);
+                    await TryMaintainConnectionAsync(cancellationToken).ConfigureAwait(false);
-                    if (connectionState == ReconnectionResult.NotConnected)
+                }
-                    {
+            }
-                        _publishingCancellationToken?.Cancel(false);
+            catch (OperationCanceledException)
-                        _publishingCancellationToken = null;
+            {
+            }
+            catch (Exception exception)
+            {
+                _logger.Error<ManagedMqttClient>(exception, "Unhandled exception while maintaining connection.");
+            }
+            finally
+            {
+                await _mqttClient.DisconnectAsync().ConfigureAwait(false);
+                _logger.Info<ManagedMqttClient>("Stopped");
+            }
+        }
 
-                        await Task.Delay(_options.AutoReconnectDelay, cancellationToken).ConfigureAwait(false);
+        private async Task TryMaintainConnectionAsync(CancellationToken cancellationToken)
-                        continue;
+        {
-                    }
+            try
+            {
+                var connectionState = await ReconnectIfRequiredAsync().ConfigureAwait(false);
+                if (connectionState == ReconnectionResult.NotConnected)
+                {
+                    StopPublishing();
+                    await Task.Delay(_options.AutoReconnectDelay, cancellationToken).ConfigureAwait(false);
+                    return;
+                }
 
-                    if (connectionState == ReconnectionResult.Reconnected || _subscriptionsNotPushed)
+                if (connectionState == ReconnectionResult.Reconnected || _subscriptionsNotPushed)
-                    {
+                {
-                        await PushSubscriptionsAsync();
+                    await SynchronizeSubscriptionsAsync().ConfigureAwait(false);
 
-                        _publishingCancellationToken = new CancellationTokenSource();
+                    StartPublishing();
 
-#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
-                        Task.Run(async () => await PublishQueuedMessagesAsync(_publishingCancellationToken.Token), _publishingCancellationToken.Token).ConfigureAwait(false);
-#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
 
-                        continue;
+                    return;
-                    }
+                }
 
-                    if (connectionState == ReconnectionResult.StillConnected)
+                if (connectionState == ReconnectionResult.StillConnected)
-                    {
+                {
-                        await Task.Delay(TimeSpan.FromSeconds(1), _connectionCancellationToken.Token).ConfigureAwait(false);
+                    await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);
-                    }
                 }
             }
             catch (OperationCanceledException)
@@ -182,11 +213,6 @@ namespace MQTTnet.Core.ManagedClient
             {
                 _logger.Error<ManagedMqttClient>(exception, "Unhandled exception while maintaining connection.");
             }
-            finally
-            {
-                await _mqttClient.DisconnectAsync().ConfigureAwait(false);
-                _logger.Info<ManagedMqttClient>("Stopped");
-            }
         }
 
         private async Task PublishQueuedMessagesAsync(CancellationToken cancellationToken)
@@ -207,26 +233,37 @@ namespace MQTTnet.Core.ManagedClient
                     }
 
                     await TryPublishQueuedMessageAsync(message).ConfigureAwait(false);
-                    await _storageManager.RemoveAsync(message).ConfigureAwait(false);
                 }
             }
             catch (OperationCanceledException)
             {
             }
+            catch (Exception exception)
+            {
+                _logger.Error<ManagedMqttClient>(exception, "Unhandled exception while publishing queued application messages.");
+            }
             finally
             {
-                _logger.Info<ManagedMqttClient>("Stopped publishing messages");
+                _logger.Trace<ManagedMqttClient>("Stopped publishing messages.");
             }
         }
 
         private async Task TryPublishQueuedMessageAsync(MqttApplicationMessage message)
         {
+            Exception transmitException = null;
             try
             {
                 await _mqttClient.PublishAsync(message).ConfigureAwait(false);
+
+                if (_storageManager != null)
+                {
+                    await _storageManager.RemoveAsync(message).ConfigureAwait(false);
+                }
             }
             catch (MqttCommunicationException exception)
             {
+                transmitException = exception;
+
                 _logger.Warning<ManagedMqttClient>(exception, "Publishing application message failed.");
 
                 if (message.QualityOfServiceLevel > MqttQualityOfServiceLevel.AtMostOnce)
@@ -236,34 +273,60 @@ namespace MQTTnet.Core.ManagedClient
             }
             catch (Exception exception)
             {
+                transmitException = exception;
                 _logger.Error<ManagedMqttClient>(exception, "Unhandled exception while publishing queued application message.");
             }
+            finally
+            {
+                ApplicationMessageProcessed?.Invoke(this, new ApplicationMessageProcessedEventArgs(message, transmitException));
+            }
         }
 
-        private async Task PushSubscriptionsAsync()
+        private async Task SynchronizeSubscriptionsAsync()
         {
             _logger.Info<ManagedMqttClient>(nameof(ManagedMqttClient), "Synchronizing subscriptions");
 
             List<TopicFilter> subscriptions;
-            lock (_subscriptions)
+            List<string> unsubscriptions;
+
+            await _subscriptionsSemaphore.WaitAsync().ConfigureAwait(false);
+            try
             {
-                subscriptions = _subscriptions.ToList();
+                subscriptions = _subscriptions.Select(i => new TopicFilter(i.Key, i.Value)).ToList();
+
+                unsubscriptions = new List<string>(_unsubscriptions);
+                _unsubscriptions.Clear();
+
                 _subscriptionsNotPushed = false;
             }
-
+            finally
-            if (!_subscriptions.Any())
+            {
+                _subscriptionsSemaphore.Release();
+            }
+            
+            if (!subscriptions.Any() && !unsubscriptions.Any())
             {
                 return;
             }
 
             try
             {
-                await _mqttClient.SubscribeAsync(subscriptions).ConfigureAwait(false);
+                if (subscriptions.Any())
+                {
+                    await _mqttClient.SubscribeAsync(subscriptions).ConfigureAwait(false);
+                }
+
+                if (unsubscriptions.Any())
+                {
+                    await _mqttClient.UnsubscribeAsync(unsubscriptions).ConfigureAwait(false);
+                }
             }
             catch (Exception exception)
             {
-                _logger.Warning<ManagedMqttClient>(exception, "Synchronizing subscriptions failed");
+                _logger.Warning<ManagedMqttClient>(exception, "Synchronizing subscriptions failed.");
                 _subscriptionsNotPushed = true;
+
+                SynchronizingSubscriptionsFailed?.Invoke(this, EventArgs.Empty);
             }
         }
 
@@ -299,5 +362,35 @@ namespace MQTTnet.Core.ManagedClient
         {
             Connected?.Invoke(this, eventArgs);
         }
+
+        private void StartPublishing()
+        {
+            if (_publishingCancellationToken != null)
+            {
+                StopPublishing();
+            }
+
+            var cts = new CancellationTokenSource();
+
+            _publishingCancellationToken = cts;
+
+#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
+            Task.Run(async () => await PublishQueuedMessagesAsync(cts.Token).ConfigureAwait(false), cts.Token).ConfigureAwait(false);
+#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
+        }
+
+        private void StopPublishing()
+        {
+            _publishingCancellationToken?.Cancel(false);
+            _publishingCancellationToken?.Dispose();
+            _publishingCancellationToken = null;
+        }
+
+        private void StopMaintainingConnection()
+        {
+            _connectionCancellationToken?.Cancel(false);
+            _connectionCancellationToken?.Dispose();
+            _connectionCancellationToken = null;
+        }
     }
 }

Frameworks/MQTTnet.NetStandard/ManagedClient/ManagedMqttClientExtensions.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Threading.Tasks;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.ManagedClient
+{
+    public static class ManagedMqttClientExtensions
+    {
+        public static Task SubscribeAsync(this IManagedMqttClient managedClient, params TopicFilter[] topicFilters)
+        {
+            if (managedClient == null) throw new ArgumentNullException(nameof(managedClient));
+
+            return managedClient.SubscribeAsync(topicFilters);
+        }
+
+        public static Task SubscribeAsync(this IManagedMqttClient managedClient, string topic, MqttQualityOfServiceLevel qualityOfServiceLevel)
+        {
+            if (managedClient == null) throw new ArgumentNullException(nameof(managedClient));
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
+            return managedClient.SubscribeAsync(new TopicFilterBuilder().WithTopic(topic).WithQualityOfServiceLevel(qualityOfServiceLevel).Build());
+        }
+
+        public static Task SubscribeAsync(this IManagedMqttClient managedClient, string topic)
+        {
+            if (managedClient == null) throw new ArgumentNullException(nameof(managedClient));
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
+            return managedClient.SubscribeAsync(new TopicFilterBuilder().WithTopic(topic).Build());
+        }
+
+        public static Task UnsubscribeAsync(this IManagedMqttClient managedClient, params string[] topicFilters)
+        {
+            if (managedClient == null) throw new ArgumentNullException(nameof(managedClient));
+
+            return managedClient.UnsubscribeAsync(topicFilters);
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/ManagedClient/ManagedMqttClientOptions.cs

@@ -1,7 +1,7 @@
 using System;
-using MQTTnet.Core.Client;
+using MQTTnet.Client;
 
-namespace MQTTnet.Core.ManagedClient
+namespace MQTTnet.ManagedClient
 {
     public class ManagedMqttClientOptions : IManagedMqttClientOptions
     {

Frameworks/MQTTnet.NetStandard/ManagedClient/ManagedMqttClientOptionsBuilder.cs

@@ -1,11 +1,12 @@
 using System;
-using MQTTnet.Core.Client;
+using MQTTnet.Client;
 
-namespace MQTTnet.Core.ManagedClient
+namespace MQTTnet.ManagedClient
 {
     public class ManagedMqttClientOptionsBuilder
     {
         private readonly ManagedMqttClientOptions _options = new ManagedMqttClientOptions();
+        private MqttClientOptionsBuilder _clientOptionsBuilder;
 
         public ManagedMqttClientOptionsBuilder WithAutoReconnectDelay(TimeSpan value)
         {
@@ -21,7 +22,24 @@ namespace MQTTnet.Core.ManagedClient
 
         public ManagedMqttClientOptionsBuilder WithClientOptions(IMqttClientOptions value)
         {
+            if (_clientOptionsBuilder != null)
+            {
+                throw new InvalidOperationException("Cannot use client options builder and client options at the same time.");
+            }
+
             _options.ClientOptions = value ?? throw new ArgumentNullException(nameof(value));
+
+            return this;
+        }
+
+        public ManagedMqttClientOptionsBuilder WithClientOptions(MqttClientOptionsBuilder builder)
+        {
+            if (_options.ClientOptions != null)
+            {
+                throw new InvalidOperationException("Cannot use client options builder and client options at the same time.");
+            }
+
+            _clientOptionsBuilder = builder;
             return this;
         }
 
@@ -29,15 +47,22 @@ namespace MQTTnet.Core.ManagedClient
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 
-            var builder = new MqttClientOptionsBuilder();
+            if (_clientOptionsBuilder == null)
-            options(builder);
+            {
-            _options.ClientOptions = builder.Build();
+                _clientOptionsBuilder = new MqttClientOptionsBuilder();
+            }
 
+            options(_clientOptionsBuilder);
             return this;
         }
 
         public ManagedMqttClientOptions Build()
         {
+            if (_clientOptionsBuilder != null)
+            {
+                _options.ClientOptions = _clientOptionsBuilder.Build();
+            }
+
             if (_options.ClientOptions == null)
             {
                 throw new InvalidOperationException("The ClientOptions cannot be null.");

Frameworks/MQTTnet.NetStandard/ManagedClient/ManagedMqttClientStorageManager.cs

@@ -1,25 +1,27 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 
-namespace MQTTnet.Core.ManagedClient
+namespace MQTTnet.ManagedClient
 {
     public class ManagedMqttClientStorageManager
     {
         private readonly List<MqttApplicationMessage> _applicationMessages = new List<MqttApplicationMessage>();
         private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1, 1);
-        private IManagedMqttClientStorage _storage;
+        private readonly IManagedMqttClientStorage _storage;
 
-        public async Task SetStorageAsync(IManagedMqttClientStorage storage)
+        public ManagedMqttClientStorageManager(IManagedMqttClientStorage storage)
         {
-            await _semaphore.WaitAsync().ConfigureAwait(false);
+            _storage = storage ?? throw new ArgumentNullException(nameof(storage));
-            try
+        }
+
+        public async Task LoadQueuedMessagesAsync()
+        {
+            var loadedMessages = await _storage.LoadQueuedMessagesAsync().ConfigureAwait(false);
+            foreach (var loadedMessage in loadedMessages)
             {
-                _storage = storage;
+                _applicationMessages.Add(loadedMessage);
-            }
-            finally
-            {
-                _semaphore.Release();
             }
         }
 
@@ -28,11 +30,6 @@ namespace MQTTnet.Core.ManagedClient
             await _semaphore.WaitAsync().ConfigureAwait(false);
             try
             {
-                if (_storage == null)
-                {
-                    return;
-                }
-
                 _applicationMessages.Add(applicationMessage);
                 await SaveAsync().ConfigureAwait(false);
             }
@@ -47,11 +44,6 @@ namespace MQTTnet.Core.ManagedClient
             await _semaphore.WaitAsync().ConfigureAwait(false);
             try
             {
-                if (_storage == null)
-                {
-                    return;
-                }
-
                 var index = _applicationMessages.IndexOf(applicationMessage);
                 if (index == -1)
                 {

Frameworks/MQTTnet.NetStandard/ManagedClient/ReconnectionResult.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.ManagedClient
+namespace MQTTnet.ManagedClient
 {
     public enum ReconnectionResult
     {

Frameworks/MQTTnet.NetStandard/MqttApplicationMessage.cs

@@ -1,7 +1,7 @@
 using System;
-using MQTTnet.Core.Protocol;
+using MQTTnet.Protocol;
 
-namespace MQTTnet.Core
+namespace MQTTnet
 {
     public sealed class MqttApplicationMessage
     {

Frameworks/MQTTnet.NetStandard/MqttApplicationMessageBuilder.cs

@@ -2,10 +2,10 @@
 using System.IO;
 using System.Linq;
 using System.Text;
-using MQTTnet.Core.Exceptions;
+using MQTTnet.Exceptions;
-using MQTTnet.Core.Protocol;
+using MQTTnet.Protocol;
 
-namespace MQTTnet.Core
+namespace MQTTnet
 {
     public class MqttApplicationMessageBuilder
     {

Frameworks/MQTTnet.NetStandard/MqttApplicationMessageExtensions.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Text;
+
+namespace MQTTnet
+{
+    public static class MqttApplicationMessageExtensions
+    {
+        public static string ConvertPayloadToString(this MqttApplicationMessage applicationMessage)
+        {
+            if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
+
+            if (applicationMessage.Payload == null)
+            {
+                return null;
+            }
+
+            if (applicationMessage.Payload.Length == 0)
+            {
+                return string.Empty;
+            }
+
+            return Encoding.UTF8.GetString(applicationMessage.Payload, 0, applicationMessage.Payload.Length);
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/MqttApplicationMessageReceivedEventArgs.cs

@@ -1,6 +1,6 @@
 using System;
 
-namespace MQTTnet.Core
+namespace MQTTnet
 {
     public sealed class MqttApplicationMessageReceivedEventArgs : EventArgs
     {

Frameworks/MQTTnet.NetStandard/MqttFactory.cs

@@ -1,11 +1,11 @@
 using System;
 using System.Collections.Generic;
-using MQTTnet.Core.Adapter;
+using MQTTnet.Adapter;
-using MQTTnet.Core.Client;
+using MQTTnet.Client;
+using MQTTnet.Diagnostics;
 using MQTTnet.Implementations;
-using MQTTnet.Core.ManagedClient;
+using MQTTnet.ManagedClient;
-using MQTTnet.Core.Server;
+using MQTTnet.Server;
-using MQTTnet.Core.Diagnostics;
 
 namespace MQTTnet
 {

Frameworks/MQTTnet.NetStandard/Packets/IMqttPacketWithIdentifier.cs

@@ -0,0 +1,7 @@
+namespace MQTTnet.Packets
+{
+    public interface IMqttPacketWithIdentifier
+    {
+        ushort? PacketIdentifier { get; set; }
+    }
+}

Frameworks/MQTTnet.NetStandard/Packets/MqttBasePacket.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public abstract class MqttBasePacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttBasePublishPacket.cs

@@ -1,7 +1,7 @@
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public class MqttBasePublishPacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
-        public ushort PacketIdentifier { get; set; }
+        public ushort? PacketIdentifier { get; set; }
     }
 }

Frameworks/MQTTnet.NetStandard/Packets/MqttConnAckPacket.cs

@@ -1,6 +1,6 @@
-using MQTTnet.Core.Protocol;
+using MQTTnet.Protocol;
 
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttConnAckPacket : MqttBasePacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttConnectPacket.cs

@@ -1,6 +1,6 @@
-using MQTTnet.Core.Serializer;
+using MQTTnet.Serializer;
 
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttConnectPacket : MqttBasePacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttDisconnectPacket.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttDisconnectPacket : MqttBasePacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttPacketHeader.cs

@@ -1,6 +1,6 @@
-using MQTTnet.Core.Protocol;
+using MQTTnet.Protocol;
 
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public class MqttPacketHeader
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttPingReqPacket.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttPingReqPacket : MqttBasePacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttPingRespPacket.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttPingRespPacket : MqttBasePacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttPubAckPacket.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttPubAckPacket : MqttBasePublishPacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttPubCompPacket.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttPubCompPacket : MqttBasePublishPacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttPubRecPacket.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttPubRecPacket : MqttBasePublishPacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttPubRelPacket.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttPubRelPacket : MqttBasePublishPacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttPublishPacket.cs

@@ -1,6 +1,6 @@
-using MQTTnet.Core.Protocol;
+using MQTTnet.Protocol;
 
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttPublishPacket : MqttBasePublishPacket
     {

Frameworks/MQTTnet.NetStandard/Packets/MqttSubAckPacket.cs

@@ -1,12 +1,12 @@
 using System.Collections.Generic;
 using System.Linq;
-using MQTTnet.Core.Protocol;
+using MQTTnet.Protocol;
 
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttSubAckPacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
-        public ushort PacketIdentifier { get; set; }
+        public ushort? PacketIdentifier { get; set; }
 
         public IList<MqttSubscribeReturnCode> SubscribeReturnCodes { get; } = new List<MqttSubscribeReturnCode>();
 

Frameworks/MQTTnet.NetStandard/Packets/MqttSubscribePacket.cs

@@ -1,11 +1,11 @@
 using System.Collections.Generic;
 using System.Linq;
 
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttSubscribePacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
-        public ushort PacketIdentifier { get; set; }
+        public ushort? PacketIdentifier { get; set; }
 
         public IList<TopicFilter> TopicFilters { get; set; } = new List<TopicFilter>();
 

Frameworks/MQTTnet.NetStandard/Packets/MqttUnsubAckPacket.cs

@@ -1,8 +1,8 @@
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Packets
 {
     public sealed class MqttUnsubAckPacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
-        public ushort PacketIdentifier { get; set; }
+        public ushort? PacketIdentifier { get; set; }
 
         public override string ToString()
         {