Fix several bugs

Fix50 eventing

.bettercodehub.yml

@@ -0,0 +1,8 @@
+exclude:
+- /Frameworks/.*
+- /MQTTnet.TestApp.NetCore/Program.cs
+- /Tests/MQTTnet.TestApp.NetFramework/.*
+- /Tests/MQTTnet.TestApp.UniversalWindows/.*
+component_depth: 1
+languages:
+- csharp

.gitignore

@@ -1,5 +1,7 @@
 ## Ignore Visual Studio temporary files, build results, and
 ## files generated by popular Visual Studio add-ons.
+##
+## Get latest from https://github.com/github/gitignore/blob/master/VisualStudio.gitignore
 
 # User-specific files
 *.suo
@@ -15,12 +17,12 @@
 [Dd]ebugPublic/
 [Rr]elease/
 [Rr]eleases/
-[Xx]64/
-[Xx]86/
-[Bb]uild/
+x64/
+x86/
 bld/
 [Bb]in/
 [Oo]bj/
+[Ll]og/
 
 # Visual Studio 2015 cache/options directory
 .vs/
@@ -40,9 +42,11 @@ TestResult.xml
 [Rr]eleasePS/
 dlldata.c
 
-# DNX
+# .NET Core
 project.lock.json
+project.fragment.lock.json
 artifacts/
+**/Properties/launchSettings.json
 
 *_i.c
 *_p.c
@@ -81,6 +85,7 @@ ipch/
 *.sdf
 *.cachefile
 *.VC.db
+*.VC.VC.opendb
 
 # Visual Studio profiler
 *.psess
@@ -108,6 +113,10 @@ _TeamCity*
 # DotCover is a Code Coverage Tool
 *.dotCover
 
+# Visual Studio code coverage results
+*.coverage
+*.coveragexml
+
 # NCrunch
 _NCrunch_*
 .*crunch*.local.xml
@@ -139,13 +148,16 @@ publish/
 # Publish Web Output
 *.[Pp]ublish.xml
 *.azurePubxml
-
-# TODO: Un-comment the next line if you do not want to checkin 
-# your web deploy settings because they may include unencrypted
-# passwords
-#*.pubxml
+# TODO: Comment the next line if you want to checkin your web deploy settings
+# but database connection strings (with potential passwords) will be unencrypted
+*.pubxml
 *.publishproj
 
+# Microsoft Azure Web App publish settings. Comment the next line if you want to
+# checkin your Azure Web App publish settings, but sensitive information contained
+# in these scripts will be unencrypted
+PublishScripts/
+
 # NuGet Packages
 *.nupkg
 # The packages folder can be ignored because of Package Restore
@@ -154,7 +166,7 @@ publish/
 !**/packages/build/
 # Uncomment if necessary however generally it will be regenerated when needed
 #!**/packages/repositories.config
-# NuGet v3's project.json files produces more ignoreable files
+# NuGet v3's project.json files produces more ignorable files
 *.nuget.props
 *.nuget.targets
 
@@ -166,12 +178,11 @@ csx/
 ecf/
 rcf/
 
-# Microsoft Azure ApplicationInsights config file
-ApplicationInsights.config
-
-# Windows Store app package directory
+# Windows Store app package directories and files
 AppPackages/
 BundleArtifacts/
+Package.StoreAssociation.xml
+_pkginfo.txt
 
 # Visual Studio cache files
 # files ending in .cache can be ignored
@@ -181,16 +192,19 @@ BundleArtifacts/
 
 # Others
 ClientBin/
-[Ss]tyle[Cc]op.*
 ~$*
 *~
 *.dbmdl
 *.dbproj.schemaview
+*.jfm
 *.pfx
 *.publishsettings
-node_modules/
 orleans.codegen.cs
 
+# Since there are multiple workflows, uncomment next line to ignore bower_components
+# (https://github.com/github/gitignore/pull/1529#issuecomment-104372622)
+#bower_components/
+
 # RIA/Silverlight projects
 Generated_Code/
 
@@ -205,6 +219,7 @@ UpgradeLog*.htm
 # SQL Server files
 *.mdf
 *.ldf
+*.ndf
 
 # Business Intelligence projects
 *.rdl.data
@@ -219,6 +234,10 @@ FakesAssemblies/
 
 # Node.js Tools for Visual Studio
 .ntvs_analysis.dat
+node_modules/
+
+# Typescript v1 declaration files
+typings/
 
 # Visual Studio 6 build log
 *.plg
@@ -226,6 +245,9 @@ FakesAssemblies/
 # Visual Studio 6 workspace options file
 *.opt
 
+# Visual Studio 6 auto-generated workspace file (contains which files were open etc.)
+*.vbw
+
 # Visual Studio LightSwitch build output
 **/*.HTMLClient/GeneratedArtifacts
 **/*.DesktopClient/GeneratedArtifacts
@@ -234,12 +256,36 @@ FakesAssemblies/
 **/*.Server/ModelManifest.xml
 _Pvt_Extensions
 
-# LightSwitch generated files
-GeneratedArtifacts/
-ModelManifest.xml
-
 # Paket dependency manager
 .paket/paket.exe
+paket-files/
 
 # FAKE - F# Make
-.fake/
+.fake/
+
+# JetBrains Rider
+.idea/
+*.sln.iml
+
+# CodeRush
+.cr/
+
+# Python Tools for Visual Studio (PTVS)
+__pycache__/
+*.pyc
+
+# Cake - Uncomment if you are using it
+# tools/**
+# !tools/packages.config
+
+# Telerik's JustMock configuration file
+*.jmconfig
+
+# BizTalk build output
+*.btp.cs
+*.btm.cs
+*.odx.cs
+*.xsd.cs
+
+
+Build/nuget.exe

.travis.yml

@@ -0,0 +1,10 @@
+language: csharp
+solution: MQTTnet.sln
+
+matrix:
+  include:
+    - dotnet: 2.0.0
+      mono: none
+      dist: trusty
+      env: DOTNETCORE=1  # optional, can be used to take different code paths in your script
+    - mono: latest

Build/MQTTnet.nuspec

@@ -0,0 +1,55 @@
+<?xml version="1.0"?>
+<package >
+  <metadata>
+    <id>MQTTnet</id>
+    <version>2.4.0</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>MQTTnet is a .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker).</description>
+    <releaseNotes>* [Server] Added an event which is fired when a client has disconnected.
+* [Server] Added support for retained application messages
+* [Server] Added support for saving and loading retained messages
+* [Server] The client connection is now closed if sending of one pending application message has failed
+* [Server] Fixed handling of _Dup_ flag (Thanks to haeberle)
+* [Core] Optimized exception handling
+* [Core] Mono is now also supported (Thanks to JTrotta)
+* [Client] The options are now passed in _ConnectAsync_ (Breaking change! Read Wiki for examples)
+* [Core] Trace class renamed to _MqttNetTrace_ (Breaking change!)
+* [Client] Extended certificate validation options (Breaking change!)
+* [Client] Added static certificate validation callback (NetFramework, NetStandard) / ignorable certificate errors (UniversalWindows) to _MqttTcpChannel_
+    </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</tags> 
+    <dependencies>
+
+      <group targetFramework="netstandard1.3">
+        <dependency id="NETStandard.Library" version="1.6.1" />
+        <dependency id="System.Net.Security" version="4.3.2" />
+      </group>
+      
+      <group targetFramework="uap10.0">
+        <dependency id="Microsoft.NETCore.UniversalWindowsPlatform" version="5.4.0" />
+      </group>
+
+    </dependencies>
+  </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\"/>
+
+    <!-- Universal Windows -->
+    <file src="..\Frameworks\MQTTnet.UniversalWindows\bin\Release\MQTTnet.Core.*" target="lib\uap10.0\"/>
+    <file src="..\Frameworks\MQTTnet.UniversalWindows\bin\Release\MQTTnet.*" target="lib\uap10.0\"/>
+
+    <!-- .NET Framework -->
+    <file src="..\Frameworks\MQTTnet.NetFramework\bin\Release\MQTTnet.Core.*" target="lib\net45\"/>
+    <file src="..\Frameworks\MQTTnet.NetFramework\bin\Release\MQTTnet.*" target="lib\net45\"/>
+    
+  </files>
+</package>

Build/build.ps1

@@ -0,0 +1,12 @@
+param([string]$version)
+
+if ([string]::IsNullOrEmpty($version)) {$version = "0.0.1"}
+
+$msbuild = "MSBuild.exe"
+&$msbuild ..\Frameworks\MQTTnet.NetFramework\MQTTnet.NetFramework.csproj /t:Build /p:Configuration="Release"
+&$msbuild ..\Frameworks\MQTTnet.Netstandard\MQTTnet.Netstandard.csproj /t:Build /p:Configuration="Release"
+&$msbuild ..\Frameworks\MQTTnet.UniversalWindows\MQTTnet.UniversalWindows.csproj /t:Build /p:Configuration="Release"
+
+Remove-Item .\NuGet -Force -Recurse
+New-Item -ItemType Directory -Force -Path .\NuGet
+.\NuGet.exe pack MQTTnet.nuspec -Verbosity detailed -Symbols -OutputDir "NuGet" -Version $version

Frameworks/MQTTnet.NetCore/MQTTnet.NetCore.csproj

@@ -1,23 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <TargetFramework>netcoreapp1.1</TargetFramework>
-    <Authors>Christian Kratky</Authors>
-    <Company>Christian Kratky</Company>
-    <Product>MQTTnet</Product>
-    <Description>MQTTnet for .NET Core</Description>
-    <Copyright>Copyright © Christian Kratky 2016-2017</Copyright>
-    <Version>2.0.4.0</Version>
-    <AssemblyVersion>2.0.4.0</AssemblyVersion>
-    <FileVersion>2.0.4.0</FileVersion>
-    <GeneratePackageOnBuild>True</GeneratePackageOnBuild>
-    <AssemblyName>MQTTnet</AssemblyName>
-    <RootNamespace>MQTTnet</RootNamespace>
-    <PackageId>MQTTnet</PackageId>
-  </PropertyGroup>
-
-  <ItemGroup>
-    <ProjectReference Include="..\..\MQTTnet.Core\MQTTnet.Core.csproj" />
-  </ItemGroup>
-
-</Project>

Frameworks/MQTTnet.NetCore/MqttClientFactory.cs

@@ -1,17 +0,0 @@
-using System;
-using MQTTnet.Core.Adapter;
-using MQTTnet.Core.Client;
-using MQTTnet.Core.Serializer;
-
-namespace MQTTnet
-{
-    public class MqttClientFactory
-    {
-        public MqttClient CreateMqttClient(MqttClientOptions options)
-        {
-            if (options == null) throw new ArgumentNullException(nameof(options));
-
-            return new MqttClient(options, new MqttChannelCommunicationAdapter(new MqttTcpChannel(), new DefaultMqttV311PacketSerializer()));
-        }
-    }
-}

Frameworks/MQTTnet.NetCore/MqttServerAdapter.cs

@@ -1,56 +0,0 @@
-using System;
-using System.Net;
-using System.Net.Sockets;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Core.Adapter;
-using MQTTnet.Core.Serializer;
-using MQTTnet.Core.Server;
-
-namespace MQTTnet
-{
-    public sealed class MqttServerAdapter : IMqttServerAdapter, IDisposable
-    {
-        private CancellationTokenSource _cancellationTokenSource;
-        private Socket _socket;
-
-        public event EventHandler<MqttClientConnectedEventArgs> ClientConnected;
-
-        public void Start(MqttServerOptions options)
-        {
-            if (_socket != null) throw new InvalidOperationException("Server is already started.");
-
-            _cancellationTokenSource = new CancellationTokenSource();
-
-            _socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
-            _socket.Bind(new IPEndPoint(IPAddress.Any, options.Port));
-            _socket.Listen(options.ConnectionBacklog);
-            
-            Task.Run(async () => await AcceptConnectionsAsync(_cancellationTokenSource.Token), _cancellationTokenSource.Token);
-        }
-
-        public void Stop()
-        {
-            _cancellationTokenSource?.Dispose();
-            _cancellationTokenSource = null;
-
-            _socket?.Dispose();
-            _socket = null;
-        }
-
-        public void Dispose()
-        {
-            Stop();
-        }
-
-        private async Task AcceptConnectionsAsync(CancellationToken cancellationToken)
-        {
-            while (!cancellationToken.IsCancellationRequested)
-            {
-                var clientSocket = await _socket.AcceptAsync();
-                var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(clientSocket), new DefaultMqttV311PacketSerializer());    
-                ClientConnected?.Invoke(this, new MqttClientConnectedEventArgs(clientSocket.RemoteEndPoint.ToString(), clientAdapter));
-            }
-        }
-    }
-}

Frameworks/MQTTnet.NetCore/MqttServerFactory.cs

@@ -1,15 +0,0 @@
-using System;
-using MQTTnet.Core.Server;
-
-namespace MQTTnet
-{
-    public class MqttServerFactory
-    {
-        public MqttServer CreateMqttServer(MqttServerOptions options)
-        {
-            if (options == null) throw new ArgumentNullException(nameof(options));
-
-            return new MqttServer(options, new MqttServerAdapter());
-        }
-    }
-}

Frameworks/MQTTnet.NetCore/MqttTcpChannel.cs

@@ -1,81 +0,0 @@
-using System;
-using System.Net.Sockets;
-using System.Threading.Tasks;
-using MQTTnet.Core.Channel;
-using MQTTnet.Core.Client;
-using MQTTnet.Core.Exceptions;
-
-namespace MQTTnet
-{
-    public class MqttTcpChannel : IMqttCommunicationChannel, IDisposable
-    {
-        private readonly Socket _socket;
-
-        public MqttTcpChannel()
-        {
-            _socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
-        }
-
-        public MqttTcpChannel(Socket socket)
-        {
-            _socket = socket ?? throw new ArgumentNullException(nameof(socket));
-        }
-
-        public async Task ConnectAsync(MqttClientOptions options)
-        {
-            try
-            {
-                await _socket.ConnectAsync(options.Server, options.Port);
-            }
-            catch (SocketException exception)
-            {
-                throw new MqttCommunicationException(exception);
-            }
-        }
-
-        public async Task DisconnectAsync()
-        {
-            try
-            {
-                _socket.Dispose();
-                await Task.FromResult(0);
-            }
-            catch (SocketException exception)
-            {
-                throw new MqttCommunicationException(exception);
-            }
-        }
-
-        public async Task WriteAsync(byte[] buffer)
-        {
-            if (buffer == null) throw new ArgumentNullException(nameof(buffer));
-
-            try
-            {
-                await _socket.SendAsync(new ArraySegment<byte>(buffer), SocketFlags.None);
-            }
-            catch (SocketException exception)
-            {
-                throw new MqttCommunicationException(exception);
-            }
-        }
-
-        public async Task ReadAsync(byte[] buffer)
-        {
-            try
-            {
-                var buffer2 = new ArraySegment<byte>(buffer);
-                await _socket.ReceiveAsync(buffer2, SocketFlags.None);
-            }
-            catch (SocketException exception)
-            {
-                throw new MqttCommunicationException(exception);
-            }
-        }
-
-        public void Dispose()
-        {
-            _socket?.Dispose();
-        }
-    }
-}

Frameworks/MQTTnet.NetFramework/Implementations/MqttCommunicationAdapterFactory.cs

@@ -0,0 +1,27 @@
+using System;
+using MQTTnet.Core.Adapter;
+using MQTTnet.Core.Client;
+using MQTTnet.Core.Serializer;
+
+namespace MQTTnet.Implementations
+{
+    public class MqttCommunicationAdapterFactory : IMqttCommunicationAdapterFactory
+    {
+        public IMqttCommunicationAdapter CreateMqttCommunicationAdapter(MqttClientOptions options)
+        {
+            if (options == null) throw new ArgumentNullException(nameof(options));
+
+            if (options is MqttClientTcpOptions tcpOptions)
+            {
+                return new MqttChannelCommunicationAdapter(new MqttTcpChannel(tcpOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion });
+            }
+
+            if (options is MqttClientWebSocketOptions webSocketOptions)
+            {
+                return new MqttChannelCommunicationAdapter(new MqttWebSocketChannel(webSocketOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion });
+            }
+
+            throw new NotSupportedException();
+        }
+    }
+}

Frameworks/MQTTnet.NetFramework/Implementations/MqttServerAdapter.cs

@@ -0,0 +1,133 @@
+using System;
+using System.Net;
+using System.Net.Security;
+using System.Net.Sockets;
+using System.Security.Authentication;
+using System.Security.Cryptography.X509Certificates;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Core.Adapter;
+using MQTTnet.Core.Diagnostics;
+using MQTTnet.Core.Serializer;
+using MQTTnet.Core.Server;
+
+namespace MQTTnet.Implementations
+{
+    public class MqttServerAdapter : IMqttServerAdapter, IDisposable
+    {
+        private CancellationTokenSource _cancellationTokenSource;
+        private Socket _defaultEndpointSocket;
+        private Socket _tlsEndpointSocket;
+        private X509Certificate2 _tlsCertificate;
+
+        private bool _isRunning;
+
+        public event Action<IMqttCommunicationAdapter> ClientAccepted;
+
+        public Task StartAsync(MqttServerOptions options)
+        {
+            if (options == null) throw new ArgumentNullException(nameof(options));
+
+            if (_isRunning) throw new InvalidOperationException("Server is already started.");
+            _isRunning = true;
+
+            _cancellationTokenSource = new CancellationTokenSource();
+
+            if (options.DefaultEndpointOptions.IsEnabled)
+            {
+                _defaultEndpointSocket = new Socket(SocketType.Stream, ProtocolType.Tcp);
+                _defaultEndpointSocket.Bind(new IPEndPoint(IPAddress.Any, options.GetDefaultEndpointPort()));
+                _defaultEndpointSocket.Listen(options.ConnectionBacklog);
+
+                Task.Run(() => AcceptDefaultEndpointConnectionsAsync(_cancellationTokenSource.Token), _cancellationTokenSource.Token);
+            }
+
+            if (options.TlsEndpointOptions.IsEnabled)
+            {
+                if (options.TlsEndpointOptions.Certificate == null)
+                {
+                    throw new ArgumentException("TLS certificate is not set.");
+                }
+
+                _tlsCertificate = new X509Certificate2(options.TlsEndpointOptions.Certificate);
+
+                _tlsEndpointSocket = new Socket(SocketType.Stream, ProtocolType.Tcp);
+                _tlsEndpointSocket.Bind(new IPEndPoint(IPAddress.Any, options.GetTlsEndpointPort()));
+                _tlsEndpointSocket.Listen(options.ConnectionBacklog);
+
+                Task.Run(() => AcceptTlsEndpointConnectionsAsync(_cancellationTokenSource.Token), _cancellationTokenSource.Token);
+            }
+
+            return Task.FromResult(0);
+        }
+
+        public Task StopAsync()
+        {
+            _isRunning = false;
+
+            _cancellationTokenSource?.Cancel(false);
+            _cancellationTokenSource?.Dispose();
+            _cancellationTokenSource = null;
+
+            _defaultEndpointSocket?.Dispose();
+            _defaultEndpointSocket = null;
+
+            _tlsEndpointSocket?.Dispose();
+            _tlsEndpointSocket = null;
+
+            return Task.FromResult(0);
+        }
+
+        public void Dispose()
+        {
+            StopAsync();
+        }
+
+        private async Task AcceptDefaultEndpointConnectionsAsync(CancellationToken cancellationToken)
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                try
+                {
+                    var clientSocket = await Task.Factory.FromAsync(_defaultEndpointSocket.BeginAccept, _defaultEndpointSocket.EndAccept, null).ConfigureAwait(false);
+
+                    var tcpChannel = new MqttTcpChannel(clientSocket, null);
+                    var clientAdapter = new MqttChannelCommunicationAdapter(tcpChannel, new MqttPacketSerializer());
+                    ClientAccepted?.Invoke(clientAdapter);
+                }
+                catch (Exception exception) when (!(exception is ObjectDisposedException))
+                {
+                    MqttNetTrace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at default endpoint.");
+
+                    //excessive CPU consumed if in endless loop of socket errors
+                    await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);
+                }
+            }
+        }
+
+        private async Task AcceptTlsEndpointConnectionsAsync(CancellationToken cancellationToken)
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                try
+                {
+                    var clientSocket = await Task.Factory.FromAsync(_tlsEndpointSocket.BeginAccept, _tlsEndpointSocket.EndAccept, null).ConfigureAwait(false);
+
+                    var sslStream = new SslStream(new NetworkStream(clientSocket));
+                    await sslStream.AuthenticateAsServerAsync(_tlsCertificate, false, SslProtocols.Tls12, false).ConfigureAwait(false);
+
+                    var tcpChannel = new MqttTcpChannel(clientSocket, sslStream);
+                    var clientAdapter = new MqttChannelCommunicationAdapter(tcpChannel, new MqttPacketSerializer());
+                    ClientAccepted?.Invoke(clientAdapter);
+                }
+                catch (Exception exception)
+                {
+                    MqttNetTrace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at TLS endpoint.");
+
+                    //excessive CPU consumed if in endless loop of socket errors
+                    await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);
+                }
+            }
+        }
+    }
+}

Frameworks/MQTTnet.NetFramework/Implementations/MqttTcpChannel.cs

@@ -0,0 +1,150 @@
+using System;
+using System.Net.Security;
+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;
+
+namespace MQTTnet.Implementations
+{
+    public sealed class MqttTcpChannel : IMqttCommunicationChannel, IDisposable
+    {
+        private readonly MqttClientTcpOptions _options;
+
+        // 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 Socket _socket;
+        private SslStream _sslStream;
+
+        /// <summary>
+        /// called on client sockets are created in connect
+        /// </summary>
+        public MqttTcpChannel(MqttClientTcpOptions options)
+        {
+            _options = options ?? throw new ArgumentNullException(nameof(options));
+        }
+
+        /// <summary>
+        /// called on server, sockets are passed in
+        /// connect will not be called
+        /// </summary>
+        public MqttTcpChannel(Socket socket, SslStream sslStream)
+        {
+            _socket = socket ?? throw new ArgumentNullException(nameof(socket));
+            _sslStream = sslStream;
+
+            CreateStreams(socket, sslStream);
+        }
+
+        public Stream SendStream { get; private set; }
+        public Stream ReceiveStream { get; private set; }
+        public Stream RawReceiveStream { get; private set; }
+
+        public static Func<X509Certificate, X509Chain, SslPolicyErrors, MqttClientTcpOptions, bool> CustomCertificateValidationCallback { get; set; }
+
+        public async Task ConnectAsync()
+        {
+            if (_socket == null)
+            {
+                _socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
+            }
+
+            await Task.Factory.FromAsync(_socket.BeginConnect, _socket.EndConnect, _options.Server, _options.GetPort(), null).ConfigureAwait(false);
+
+            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);
+            }
+
+            CreateStreams(_socket, _sslStream);
+        }
+
+        public Task DisconnectAsync()
+        {
+            Dispose();
+            return Task.FromResult(0);
+        }
+
+        public void Dispose()
+        {
+            RawReceiveStream?.Dispose();
+            RawReceiveStream = null;
+
+            ReceiveStream?.Dispose();
+            ReceiveStream = null;
+
+            SendStream?.Dispose();
+            SendStream = null;
+
+            _socket?.Dispose();
+            _socket = null;
+
+            _sslStream?.Dispose();
+            _sslStream = null;
+        }
+
+        private void CreateStreams(Socket socket, Stream sslStream)
+        {
+            RawReceiveStream = sslStream ?? new NetworkStream(socket);
+
+            //cannot use this as default buffering prevents from receiving the first connect message
+            //need two streams otherwise read and write have to be synchronized
+            SendStream = new BufferedStream(RawReceiveStream, BufferSize);
+            ReceiveStream = new BufferedStream(RawReceiveStream, BufferSize);
+        }
+
+        private bool InternalUserCertificateValidationCallback(object sender, X509Certificate x509Certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
+        {
+            if (CustomCertificateValidationCallback != null)
+            {
+                return CustomCertificateValidationCallback(x509Certificate, chain, sslPolicyErrors, _options);
+            }
+
+            if (sslPolicyErrors == SslPolicyErrors.None)
+            {
+                return true;
+            }
+
+            if (chain.ChainStatus.Any(c => c.Status == X509ChainStatusFlags.RevocationStatusUnknown || c.Status == X509ChainStatusFlags.Revoked || c.Status == X509ChainStatusFlags.RevocationStatusUnknown))
+            {
+                if (!_options.TlsOptions.IgnoreCertificateRevocationErrors)
+                {
+                    return false;
+                }
+            }
+
+            if (chain.ChainStatus.Any(c => c.Status == X509ChainStatusFlags.PartialChain))
+            {
+                if (!_options.TlsOptions.IgnoreCertificateChainErrors)
+                {
+                    return false;
+                }
+            }
+            
+            return _options.TlsOptions.AllowUntrustedCertificates;
+        }
+
+        private static X509CertificateCollection LoadCertificates(MqttClientOptions options)
+        {
+            var certificates = new X509CertificateCollection();
+            if (options.TlsOptions.Certificates == null)
+            {
+                return certificates;
+            }
+
+            foreach (var certificate in options.TlsOptions.Certificates)
+            {
+                certificates.Add(new X509Certificate(certificate));
+            }
+
+            return certificates;
+        }
+    }
+}

Frameworks/MQTTnet.NetFramework/Implementations/MqttWebSocketChannel.cs

@@ -0,0 +1,57 @@
+using MQTTnet.Core.Channel;
+using MQTTnet.Core.Client;
+using System;
+using System.IO;
+using System.Net.WebSockets;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Implementations
+{
+    public sealed class MqttWebSocketChannel : IMqttCommunicationChannel, IDisposable
+    {
+        private readonly MqttClientWebSocketOptions _options;
+
+        private ClientWebSocket _webSocket;
+
+        public MqttWebSocketChannel(MqttClientWebSocketOptions options)
+        {
+            _options = options ?? throw new ArgumentNullException(nameof(options));
+        }
+
+        public Stream RawReceiveStream { get; private set; }
+        public Stream SendStream => RawReceiveStream;
+        public Stream ReceiveStream => RawReceiveStream;
+        
+        public async Task ConnectAsync()
+        {
+            var uri = _options.Uri;
+            if (!uri.StartsWith("ws://", StringComparison.OrdinalIgnoreCase))
+            {
+                uri = "ws://" + uri;
+            }
+ 
+            _webSocket = new ClientWebSocket();
+            _webSocket.Options.KeepAliveInterval = _options.KeepAlivePeriod;
+            await _webSocket.ConnectAsync(new Uri(uri), CancellationToken.None).ConfigureAwait(false);
+            RawReceiveStream = new WebSocketStream(_webSocket);
+        }
+
+        public async Task DisconnectAsync()
+        {
+            RawReceiveStream = null;
+
+            if (_webSocket == null)
+            {
+                return;
+            }
+
+            await _webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, CancellationToken.None).ConfigureAwait(false);
+        }
+
+        public void Dispose()
+        {
+            _webSocket?.Dispose();
+        }
+    }
+}

Frameworks/MQTTnet.NetFramework/Implementations/WebSocketStream.cs

@@ -0,0 +1,77 @@
+using System;
+using System.IO;
+using System.Net.WebSockets;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Implementations
+{
+    public class WebSocketStream : Stream
+    {
+        private readonly ClientWebSocket _webSocket;
+
+        public WebSocketStream(ClientWebSocket webSocket)
+        {
+            _webSocket = webSocket;
+        }
+
+        public override void Flush()
+        {
+        }
+
+        public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            var currentOffset = offset;
+            var targetOffset = offset + count;
+            while (_webSocket.State == WebSocketState.Open && currentOffset < targetOffset)
+            {
+                var response = await _webSocket.ReceiveAsync(new ArraySegment<byte>(buffer, currentOffset, count), cancellationToken).ConfigureAwait(false);
+                currentOffset += response.Count;
+
+                if (response.MessageType == WebSocketMessageType.Close)
+                {
+                    await _webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, cancellationToken).ConfigureAwait(false);
+                }
+            }
+
+            return currentOffset - offset;
+        }
+
+        public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            return _webSocket.SendAsync(new ArraySegment<byte>(buffer, offset, count), WebSocketMessageType.Binary, true, cancellationToken);
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            return ReadAsync(buffer, offset, count).GetAwaiter().GetResult();
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            WriteAsync(buffer, offset, count).GetAwaiter().GetResult();
+        }
+
+        public override bool CanRead => true;
+        public override bool CanSeek => false;
+        public override bool CanWrite => true;
+
+        public override long Length => throw new NotSupportedException();
+
+        public override long Position
+        {
+            get => throw new NotSupportedException();
+            set => throw new NotSupportedException();
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            throw new NotSupportedException();
+        }
+
+        public override void SetLength(long value)
+        {
+            throw new NotSupportedException();
+        }
+    }
+}

Frameworks/MQTTnet.NetFramework/MQTTnet.NetFramework.csproj

@@ -32,20 +32,86 @@
     <WarningLevel>4</WarningLevel>
     <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Any CPU|AnyCPU'">
+    <OutputPath>bin\Any CPU\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <Optimize>true</Optimize>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x86'">
+    <DebugSymbols>true</DebugSymbols>
+    <OutputPath>bin\x86\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <DebugType>full</DebugType>
+    <PlatformTarget>x86</PlatformTarget>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
+    <OutputPath>bin\x86\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <Optimize>true</Optimize>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>x86</PlatformTarget>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Any CPU|x86'">
+    <OutputPath>bin\x86\Any CPU\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <Optimize>true</Optimize>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>x86</PlatformTarget>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x64'">
+    <DebugSymbols>true</DebugSymbols>
+    <OutputPath>bin\x64\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <DebugType>full</DebugType>
+    <PlatformTarget>x64</PlatformTarget>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x64'">
+    <OutputPath>bin\x64\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <Optimize>true</Optimize>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>x64</PlatformTarget>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Any CPU|x64'">
+    <OutputPath>bin\x64\Any CPU\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <Optimize>true</Optimize>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>x64</PlatformTarget>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="System.Core" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Implementations\MqttCommunicationAdapterFactory.cs" />
+    <Compile Include="Implementations\MqttWebSocketChannel.cs" />
+    <Compile Include="Implementations\WebSocketStream.cs" />
     <Compile Include="MqttClientFactory.cs" />
-    <Compile Include="MqttServerAdapter.cs" />
     <Compile Include="MqttServerFactory.cs" />
+    <Compile Include="Implementations\MqttServerAdapter.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="MqttTcpChannel.cs" />
+    <Compile Include="Implementations\MqttTcpChannel.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\MQTTnet.Core\MQTTnet.Core.csproj">
-      <Project>{99C884F3-B4B9-417D-AA92-DC7DD1C4CFEE}</Project>
+      <Project>{2ecb99e4-72d0-4c23-99ba-93d511d3967d}</Project>
       <Name>MQTTnet.Core</Name>
     </ProjectReference>
   </ItemGroup>

Frameworks/MQTTnet.NetFramework/MqttClientFactory.cs

@@ -1,17 +1,13 @@
-using System;
-using MQTTnet.Core.Adapter;
-using MQTTnet.Core.Client;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Core.Client;
+using MQTTnet.Implementations;
 
 namespace MQTTnet
 {
-    public class MqttClientFactory
+    public class MqttClientFactory : IMqttClientFactory
     {
-        public MqttClient CreateMqttClient(MqttClientOptions options)
+        public IMqttClient CreateMqttClient()
         {
-            if (options == null) throw new ArgumentNullException(nameof(options));
-
-            return new MqttClient(options, new MqttChannelCommunicationAdapter(new MqttTcpChannel(), new DefaultMqttV311PacketSerializer()));
+            return new MqttClient(new MqttCommunicationAdapterFactory());
         }
     }
-}
+}

Frameworks/MQTTnet.NetFramework/MqttServerAdapter.cs

@@ -1,56 +0,0 @@
-using System;
-using System.Net;
-using System.Net.Sockets;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Core.Adapter;
-using MQTTnet.Core.Serializer;
-using MQTTnet.Core.Server;
-
-namespace MQTTnet
-{
-    public sealed class MqttServerAdapter : IMqttServerAdapter, IDisposable
-    {
-        private CancellationTokenSource _cancellationTokenSource;
-        private Socket _socket;
-
-        public event EventHandler<MqttClientConnectedEventArgs> ClientConnected;
-
-        public void Start(MqttServerOptions options)
-        {
-            if (_socket != null) throw new InvalidOperationException("Server is already started.");
-
-            _cancellationTokenSource = new CancellationTokenSource();
-
-            _socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
-            _socket.Bind(new IPEndPoint(IPAddress.Any, options.Port));
-            _socket.Listen(options.ConnectionBacklog);
-            
-            Task.Run(async () => await AcceptConnectionsAsync(_cancellationTokenSource.Token), _cancellationTokenSource.Token);
-        }
-
-        public void Stop()
-        {
-            _cancellationTokenSource?.Dispose();
-            _cancellationTokenSource = null;
-
-            _socket?.Dispose();
-            _socket = null;
-        }
-
-        public void Dispose()
-        {
-            Stop();
-        }
-
-        private async Task AcceptConnectionsAsync(CancellationToken cancellationToken)
-        {
-            while (!cancellationToken.IsCancellationRequested)
-            {
-                var clientSocket = await Task.Factory.FromAsync(_socket.BeginAccept, _socket.EndAccept, null);
-                var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(clientSocket), new DefaultMqttV311PacketSerializer());    
-                ClientConnected?.Invoke(this, new MqttClientConnectedEventArgs(clientSocket.RemoteEndPoint.ToString(), clientAdapter));
-            }
-        }
-    }
-}

Frameworks/MQTTnet.NetFramework/MqttServerFactory.cs

@@ -1,15 +1,18 @@
 using System;
+using System.Collections.Generic;
+using MQTTnet.Core.Adapter;
 using MQTTnet.Core.Server;
+using MQTTnet.Implementations;
 
 namespace MQTTnet
 {
-    public class MqttServerFactory
+    public class MqttServerFactory : IMqttServerFactory
     {
-        public MqttServer CreateMqttServer(MqttServerOptions options)
+        public IMqttServer CreateMqttServer(MqttServerOptions options)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 
-            return new MqttServer(options, new MqttServerAdapter());
+            return new MqttServer(options, new List<IMqttServerAdapter> { new MqttServerAdapter() });
         }
     }
 }

Frameworks/MQTTnet.NetFramework/MqttTcpChannel.cs

@@ -1,85 +0,0 @@
-using System;
-using System.Net.Sockets;
-using System.Threading.Tasks;
-using MQTTnet.Core.Channel;
-using MQTTnet.Core.Client;
-using MQTTnet.Core.Exceptions;
-
-namespace MQTTnet
-{
-    public class MqttTcpChannel : IMqttCommunicationChannel, IDisposable
-    {
-        private readonly Socket _socket;
-
-        public MqttTcpChannel()
-        {
-            _socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
-        }
-
-        public MqttTcpChannel(Socket socket)
-        {
-            _socket = socket ?? throw new ArgumentNullException(nameof(socket));
-        }
-
-        public async Task ConnectAsync(MqttClientOptions options)
-        {
-            try
-            {
-                await Task.Factory.FromAsync(_socket.BeginConnect, _socket.EndConnect, options.Server, options.Port, null);
-            }
-            catch (SocketException exception)
-            {
-                throw new MqttCommunicationException(exception);
-            }
-        }
-
-        public async Task DisconnectAsync()
-        {
-            try
-            {
-                await Task.Factory.FromAsync(_socket.BeginDisconnect, _socket.EndDisconnect, true, null);
-            }
-            catch (SocketException exception)
-            {
-                throw new MqttCommunicationException(exception);
-            }
-        }
-
-        public async Task WriteAsync(byte[] buffer)
-        {
-            if (buffer == null) throw new ArgumentNullException(nameof(buffer));
-
-            try
-            {
-                await Task.Factory.FromAsync(
-                    // ReSharper disable once AssignNullToNotNullAttribute
-                    _socket.BeginSend(buffer, 0, buffer.Length, SocketFlags.None, null, null),
-                    _socket.EndSend);
-            }
-            catch (SocketException exception)
-            {
-                throw new MqttCommunicationException(exception);
-            }
-        }
-
-        public async Task ReadAsync(byte[] buffer)
-        {
-            try
-            {
-                await Task.Factory.FromAsync(
-                    // ReSharper disable once AssignNullToNotNullAttribute
-                    _socket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, null, null),
-                    _socket.EndReceive);
-            }
-            catch (SocketException exception)
-            {
-                throw new MqttCommunicationException(exception);
-            }
-        }
-
-        public void Dispose()
-        {
-            _socket?.Dispose();
-        }
-    }
-}

Frameworks/MQTTnet.NetFramework/Properties/AssemblyInfo.cs

@@ -11,5 +11,5 @@ using System.Runtime.InteropServices;
 [assembly: AssemblyCulture("")]
 [assembly: ComVisible(false)]
 [assembly: Guid("a480ef90-0eaa-4d9a-b271-47a9c47f6f7d")]
-[assembly: AssemblyVersion("2.1.0.4")]
-[assembly: AssemblyFileVersion("2.1.0.4")]
+[assembly: AssemblyVersion("2.4.0.0")]
+[assembly: AssemblyFileVersion("2.4.0.0")]

Frameworks/MQTTnet.NetStandard/Implementations/MqttCommunicationAdapterFactory.cs

@@ -0,0 +1,27 @@
+using System;
+using MQTTnet.Core.Adapter;
+using MQTTnet.Core.Client;
+using MQTTnet.Core.Serializer;
+
+namespace MQTTnet.Implementations
+{
+    public class MqttCommunicationAdapterFactory : IMqttCommunicationAdapterFactory
+    {
+        public IMqttCommunicationAdapter CreateMqttCommunicationAdapter(MqttClientOptions options)
+        {
+            if (options == null) throw new ArgumentNullException(nameof(options));
+
+            if (options is MqttClientTcpOptions tcpOptions)
+            {
+                return new MqttChannelCommunicationAdapter(new MqttTcpChannel(tcpOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion });
+            }
+
+            if (options is MqttClientWebSocketOptions webSocketOptions)
+            {
+                return new MqttChannelCommunicationAdapter(new MqttWebSocketChannel(webSocketOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion });
+            }
+
+            throw new NotSupportedException();
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/Implementations/MqttServerAdapter.cs

@@ -0,0 +1,129 @@
+using System;
+using System.Net;
+using System.Net.Security;
+using System.Net.Sockets;
+using System.Security.Authentication;
+using System.Security.Cryptography.X509Certificates;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Core.Adapter;
+using MQTTnet.Core.Diagnostics;
+using MQTTnet.Core.Serializer;
+using MQTTnet.Core.Server;
+
+namespace MQTTnet.Implementations
+{
+    public class MqttServerAdapter : IMqttServerAdapter, IDisposable
+    {
+        private CancellationTokenSource _cancellationTokenSource;
+        private Socket _defaultEndpointSocket;
+        private Socket _tlsEndpointSocket;
+        private X509Certificate2 _tlsCertificate;
+
+        private bool _isRunning;
+
+        public event Action<IMqttCommunicationAdapter> ClientAccepted;
+
+        public Task StartAsync(MqttServerOptions options)
+        {
+            if (_isRunning) throw new InvalidOperationException("Server is already started.");
+
+            _isRunning = true;
+
+            _cancellationTokenSource = new CancellationTokenSource();
+
+            if (options.DefaultEndpointOptions.IsEnabled)
+            {
+                _defaultEndpointSocket = new Socket(SocketType.Stream, ProtocolType.Tcp);
+                _defaultEndpointSocket.Bind(new IPEndPoint(IPAddress.Any, options.GetDefaultEndpointPort()));
+                _defaultEndpointSocket.Listen(options.ConnectionBacklog);
+
+                Task.Run(() => AcceptDefaultEndpointConnectionsAsync(_cancellationTokenSource.Token), _cancellationTokenSource.Token);
+            }
+
+            if (options.TlsEndpointOptions.IsEnabled)
+            {
+                if (options.TlsEndpointOptions.Certificate == null)
+                {
+                    throw new ArgumentException("TLS certificate is not set.");
+                }
+
+                _tlsCertificate = new X509Certificate2(options.TlsEndpointOptions.Certificate);
+
+                _tlsEndpointSocket = new Socket(SocketType.Stream, ProtocolType.Tcp);
+                _tlsEndpointSocket.Bind(new IPEndPoint(IPAddress.Any, options.GetTlsEndpointPort()));
+                _tlsEndpointSocket.Listen(options.ConnectionBacklog);
+
+                Task.Run(() => AcceptTlsEndpointConnectionsAsync(_cancellationTokenSource.Token), _cancellationTokenSource.Token);
+            }
+
+            return Task.FromResult(0);
+        }
+
+        public Task StopAsync()
+        {
+            _isRunning = false;
+
+            _cancellationTokenSource?.Cancel(false);
+            _cancellationTokenSource?.Dispose();
+            _cancellationTokenSource = null;
+
+            _defaultEndpointSocket?.Dispose();
+            _defaultEndpointSocket = null;
+
+            _tlsEndpointSocket?.Dispose();
+            _tlsEndpointSocket = null;
+
+            return Task.FromResult(0);
+        }
+
+        public void Dispose()
+        {
+            StopAsync();
+        }
+
+        private async Task AcceptDefaultEndpointConnectionsAsync(CancellationToken cancellationToken)
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                try
+                {
+                    var clientSocket = await _defaultEndpointSocket.AcceptAsync().ConfigureAwait(false);
+                    var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(clientSocket, null), new MqttPacketSerializer());
+                    ClientAccepted?.Invoke(clientAdapter);
+                }
+                catch (Exception exception)
+                {
+                    MqttNetTrace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at default endpoint.");
+
+                    //excessive CPU consumed if in endless loop of socket errors
+                    await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);
+                }
+            }
+        }
+
+        private async Task AcceptTlsEndpointConnectionsAsync(CancellationToken cancellationToken)
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                try
+                {
+                    var clientSocket = await _tlsEndpointSocket.AcceptAsync().ConfigureAwait(false);
+
+                    var sslStream = new SslStream(new NetworkStream(clientSocket));
+                    await sslStream.AuthenticateAsServerAsync(_tlsCertificate, false, SslProtocols.Tls12, false).ConfigureAwait(false);
+
+                    var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(clientSocket, sslStream), new MqttPacketSerializer());
+                    ClientAccepted?.Invoke(clientAdapter);
+                }
+                catch (Exception exception)
+                {
+                    MqttNetTrace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at TLS endpoint.");
+
+                    //excessive CPU consumed if in endless loop of socket errors
+                    await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);
+                }
+            }
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.cs

@@ -0,0 +1,129 @@
+using System;
+using System.Net.Security;
+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;
+
+namespace MQTTnet.Implementations
+{
+    public sealed class MqttTcpChannel : IMqttCommunicationChannel, IDisposable
+    {
+        private readonly MqttClientTcpOptions _options;
+
+        private Socket _socket;
+        private SslStream _sslStream;
+        
+        /// <summary>
+        /// called on client sockets are created in connect
+        /// </summary>
+        public MqttTcpChannel(MqttClientTcpOptions options)
+        {
+            _options = options ?? throw new ArgumentNullException(nameof(options));
+        }
+
+        /// <summary>
+        /// called on server, sockets are passed in
+        /// connect will not be called
+        /// </summary>
+        public MqttTcpChannel(Socket socket, SslStream sslStream)
+        {
+            _socket = socket ?? throw new ArgumentNullException(nameof(socket));
+            _sslStream = sslStream;
+            ReceiveStream = (Stream)sslStream ?? new NetworkStream(socket);
+        }
+
+        public Stream SendStream => ReceiveStream;
+        public Stream ReceiveStream { get; private set; }
+        public Stream RawReceiveStream => ReceiveStream;
+
+        public static Func<X509Certificate, X509Chain, SslPolicyErrors, MqttClientTcpOptions, bool> CustomCertificateValidationCallback { get; set; }
+
+        public async Task ConnectAsync()
+        {
+            if (_socket == null)
+            {
+                _socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
+            }
+
+            await _socket.ConnectAsync(_options.Server, _options.GetPort()).ConfigureAwait(false);
+
+            if (_options.TlsOptions.UseTls)
+            {
+                _sslStream = new SslStream(new NetworkStream(_socket, true), false, InternalUserCertificateValidationCallback);
+                ReceiveStream = _sslStream;
+                await _sslStream.AuthenticateAsClientAsync(_options.Server, LoadCertificates(_options), SslProtocols.Tls12, _options.TlsOptions.IgnoreCertificateRevocationErrors).ConfigureAwait(false);
+            }
+            else
+            {
+                ReceiveStream = new NetworkStream(_socket);
+            }
+        }
+
+        public Task DisconnectAsync()
+        {
+            Dispose();
+            return Task.FromResult(0);
+        }
+
+        public void Dispose()
+        {
+            _socket?.Dispose();
+            _socket = null;
+
+            _sslStream?.Dispose();
+            _sslStream = null;
+        }
+
+        private bool InternalUserCertificateValidationCallback(object sender, X509Certificate x509Certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
+        {
+            if (CustomCertificateValidationCallback != null)
+            {
+                return CustomCertificateValidationCallback(x509Certificate, chain, sslPolicyErrors, _options);
+            }
+
+            if (sslPolicyErrors == SslPolicyErrors.None)
+            {
+                return true;
+            }
+
+            if (chain.ChainStatus.Any(c => c.Status == X509ChainStatusFlags.RevocationStatusUnknown || c.Status == X509ChainStatusFlags.Revoked || c.Status == X509ChainStatusFlags.RevocationStatusUnknown))
+            {
+                if (!_options.TlsOptions.IgnoreCertificateRevocationErrors)
+                {
+                    return false;
+                }
+            }
+
+            if (chain.ChainStatus.Any(c => c.Status == X509ChainStatusFlags.PartialChain))
+            {
+                if (!_options.TlsOptions.IgnoreCertificateChainErrors)
+                {
+                    return false;
+                }
+            }
+
+            return _options.TlsOptions.AllowUntrustedCertificates;
+        }
+
+        private static X509CertificateCollection LoadCertificates(MqttClientOptions options)
+        {
+            var certificates = new X509CertificateCollection();
+            if (options.TlsOptions.Certificates == null)
+            {
+                return certificates;
+            }
+
+            foreach (var certificate in options.TlsOptions.Certificates)
+            {
+                certificates.Add(new X509Certificate(certificate));
+            }
+
+            return certificates;
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/Implementations/MqttWebSocketChannel.cs

@@ -0,0 +1,56 @@
+using MQTTnet.Core.Channel;
+using MQTTnet.Core.Client;
+using System;
+using System.IO;
+using System.Net.WebSockets;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Implementations
+{
+    public sealed class MqttWebSocketChannel : IMqttCommunicationChannel, IDisposable
+    {
+        private readonly MqttClientWebSocketOptions _options;
+        private ClientWebSocket _webSocket;
+
+        public MqttWebSocketChannel(MqttClientWebSocketOptions options)
+        {
+            _options = options ?? throw new ArgumentNullException(nameof(options));
+        }
+
+        public Stream SendStream => RawReceiveStream;
+        public Stream ReceiveStream => RawReceiveStream;
+        public Stream RawReceiveStream { get; private set; }
+
+        public async Task ConnectAsync()
+        {
+            var uri = _options.Uri;
+            if (!uri.StartsWith("ws://", StringComparison.OrdinalIgnoreCase))
+            {
+                uri = "ws://" + uri;
+            }
+
+            _webSocket = new ClientWebSocket();
+            _webSocket.Options.KeepAliveInterval = _options.KeepAlivePeriod;
+            await _webSocket.ConnectAsync(new Uri(uri), CancellationToken.None);
+            RawReceiveStream = new WebSocketStream(_webSocket);
+        }
+
+        public async Task DisconnectAsync()
+        {
+            RawReceiveStream = null;
+
+            if (_webSocket == null)
+            {
+                return;
+            }
+
+            await _webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, CancellationToken.None).ConfigureAwait(false);
+        }
+
+        public void Dispose()
+        {
+            _webSocket?.Dispose();
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/Implementations/WebSocketStream.cs

@@ -0,0 +1,79 @@
+using System;
+using System.IO;
+using System.Net.WebSockets;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Implementations
+{
+    public class WebSocketStream : Stream
+    {
+        private readonly ClientWebSocket _webSocket;
+        
+        public WebSocketStream(ClientWebSocket webSocket)
+        {
+            _webSocket = webSocket;
+        }
+
+        public override bool CanRead => true;
+
+        public override bool CanSeek => false;
+
+        public override bool CanWrite => true;
+
+        public override long Length => throw new NotSupportedException();
+
+        public override long Position
+        {
+            get => throw new NotSupportedException();
+            set => throw new NotSupportedException();
+        }
+
+        public override void Flush()
+        {
+        }
+
+        public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            var currentOffset = offset;
+            var targetOffset = offset + count;
+            while (_webSocket.State == WebSocketState.Open && currentOffset < targetOffset)
+            {
+                var response = await _webSocket.ReceiveAsync(new ArraySegment<byte>(buffer, currentOffset, count), cancellationToken).ConfigureAwait(false);
+                currentOffset += response.Count;
+
+                if (response.MessageType == WebSocketMessageType.Close)
+                {
+                    await _webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, cancellationToken).ConfigureAwait(false);
+                }
+            }
+
+            return currentOffset - offset;
+        }
+
+        public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            return _webSocket.SendAsync(new ArraySegment<byte>(buffer, offset, count), WebSocketMessageType.Binary, true, cancellationToken);
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            return ReadAsync(buffer, offset, count).GetAwaiter().GetResult();
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            WriteAsync(buffer, offset, count).GetAwaiter().GetResult();
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            throw new NotSupportedException();
+        }
+
+        public override void SetLength(long value)
+        {
+            throw new NotSupportedException();
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/MQTTnet.Netstandard.csproj

@@ -0,0 +1,32 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard1.3</TargetFramework>
+    <AssemblyName>MQTTnet</AssemblyName>
+    <RootNamespace>MQTTnet</RootNamespace>
+    <AssemblyVersion>2.4.0.0</AssemblyVersion>
+    <FileVersion>2.4.0.0</FileVersion>
+    <Version>0.0.0.0</Version>
+    <Company />
+    <Product />
+    <Description />
+    <Authors />
+    <PackageId />
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x86'" />
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" />
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\MQTTnet.Core\MQTTnet.Core.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="System.Net.Security" Version="4.3.2" />
+    <PackageReference Include="System.Net.WebSockets" Version="4.3.0" />
+    <PackageReference Include="System.Net.WebSockets.Client" Version="4.3.1" />
+    <PackageReference Include="System.Threading.Thread" Version="4.3.0" />
+  </ItemGroup>
+
+</Project>

Frameworks/MQTTnet.NetStandard/MqttClientFactory.cs

@@ -0,0 +1,13 @@
+using MQTTnet.Core.Client;
+using MQTTnet.Implementations;
+
+namespace MQTTnet
+{
+    public class MqttClientFactory : IMqttClientFactory
+    {
+        public IMqttClient CreateMqttClient()
+        {
+            return new MqttClient(new MqttCommunicationAdapterFactory());
+        }
+    }
+}

Frameworks/MQTTnet.NetStandard/MqttServerFactory.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using MQTTnet.Core.Adapter;
+using MQTTnet.Core.Server;
+using MQTTnet.Implementations;
+
+namespace MQTTnet
+{
+    public class MqttServerFactory : IMqttServerFactory
+    {
+        public IMqttServer CreateMqttServer(MqttServerOptions options)
+        {
+            if (options == null) throw new ArgumentNullException(nameof(options));
+
+            return new MqttServer(options, new List<IMqttServerAdapter> { new MqttServerAdapter() });
+        }
+    }
+}

Frameworks/MQTTnet.UniversalWindows/Implementations/MqttCommunicationAdapterFactory.cs

@@ -0,0 +1,27 @@
+using System;
+using MQTTnet.Core.Adapter;
+using MQTTnet.Core.Client;
+using MQTTnet.Core.Serializer;
+
+namespace MQTTnet.Implementations
+{
+    public class MqttCommunicationAdapterFactory : IMqttCommunicationAdapterFactory
+    {
+        public IMqttCommunicationAdapter CreateMqttCommunicationAdapter(MqttClientOptions options)
+        {
+            if (options == null) throw new ArgumentNullException(nameof(options));
+
+            if (options is MqttClientTcpOptions tcpOptions)
+            {
+                return new MqttChannelCommunicationAdapter(new MqttTcpChannel(tcpOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion });
+            }
+
+            if (options is MqttClientWebSocketOptions webSocketOptions)
+            {
+                return new MqttChannelCommunicationAdapter(new MqttWebSocketChannel(webSocketOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion });
+            }
+
+            throw new NotSupportedException();
+        }
+    }
+}

Frameworks/MQTTnet.UniversalWindows/Implementations/MqttServerAdapter.cs

@@ -0,0 +1,68 @@
+using System;
+using System.Threading.Tasks;
+using MQTTnet.Core.Adapter;
+using MQTTnet.Core.Diagnostics;
+using MQTTnet.Core.Serializer;
+using MQTTnet.Core.Server;
+using Windows.Networking.Sockets;
+
+namespace MQTTnet.Implementations
+{
+    public class MqttServerAdapter : IMqttServerAdapter, IDisposable
+    {
+        private StreamSocketListener _defaultEndpointSocket;
+
+        private bool _isRunning;
+
+        public event Action<IMqttCommunicationAdapter> ClientAccepted;
+
+        public async Task StartAsync(MqttServerOptions options)
+        {
+            if (options == null) throw new ArgumentNullException(nameof(options));
+
+            if (_isRunning) throw new InvalidOperationException("Server is already started.");
+
+            _isRunning = true;
+
+            if (options.DefaultEndpointOptions.IsEnabled)
+            {
+                _defaultEndpointSocket = new StreamSocketListener();
+                await _defaultEndpointSocket.BindServiceNameAsync(options.GetDefaultEndpointPort().ToString(), SocketProtectionLevel.PlainSocket);
+                _defaultEndpointSocket.ConnectionReceived += AcceptDefaultEndpointConnectionsAsync;
+            }
+
+            if (options.TlsEndpointOptions.IsEnabled)
+            {
+                throw new NotSupportedException("TLS servers are not supported for UWP apps.");
+            }
+        }
+
+        public Task StopAsync()
+        {
+            _isRunning = false;
+
+            _defaultEndpointSocket?.Dispose();
+            _defaultEndpointSocket = null;
+
+            return Task.FromResult(0);
+        }
+
+        public void Dispose()
+        {
+            StopAsync();
+        }
+
+        private void AcceptDefaultEndpointConnectionsAsync(StreamSocketListener sender, StreamSocketListenerConnectionReceivedEventArgs args)
+        {
+            try
+            {
+                var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(args.Socket), new MqttPacketSerializer());
+                ClientAccepted?.Invoke(clientAdapter);
+            }
+            catch (Exception exception)
+            {
+                MqttNetTrace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at default endpoint.");
+            }
+        }
+    }
+}

Frameworks/MQTTnet.UniversalWindows/Implementations/MqttTcpChannel.cs

@@ -0,0 +1,136 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices.WindowsRuntime;
+using System.Threading.Tasks;
+using Windows.Networking;
+using Windows.Networking.Sockets;
+using Windows.Security.Cryptography.Certificates;
+using MQTTnet.Core.Channel;
+using MQTTnet.Core.Client;
+
+namespace MQTTnet.Implementations
+{
+    public sealed class MqttTcpChannel : IMqttCommunicationChannel, IDisposable
+    {
+        private readonly MqttClientTcpOptions _options;
+        private StreamSocket _socket;
+
+        public MqttTcpChannel(MqttClientTcpOptions options)
+        {
+            _options = options ?? throw new ArgumentNullException(nameof(options));
+        }
+
+        public MqttTcpChannel(StreamSocket socket)
+        {
+            _socket = socket ?? throw new ArgumentNullException(nameof(socket));
+
+            CreateStreams();
+        }
+
+        public Stream SendStream { get; private set; }
+        public Stream ReceiveStream { get; private set; }
+        public Stream RawReceiveStream { get; private set; }
+
+        public static Func<MqttClientTcpOptions, IEnumerable<ChainValidationResult>> CustomIgnorableServerCertificateErrorsResolver { get; set; }
+
+        public async Task ConnectAsync()
+        {
+            if (_socket == null)
+            {
+                _socket = new StreamSocket();
+            }
+
+            if (!_options.TlsOptions.UseTls)
+            {
+                await _socket.ConnectAsync(new HostName(_options.Server), _options.GetPort().ToString());
+            }
+            else
+            {
+                _socket.Control.ClientCertificate = LoadCertificate(_options);
+
+                foreach (var ignorableChainValidationResult in ResolveIgnorableServerCertificateErrors())
+                {
+                    _socket.Control.IgnorableServerCertificateErrors.Add(ignorableChainValidationResult);
+                }
+
+                await _socket.ConnectAsync(new HostName(_options.Server), _options.GetPort().ToString(), SocketProtectionLevel.Tls12);
+            }
+
+            CreateStreams();
+        }
+
+        public Task DisconnectAsync()
+        {
+            Dispose();
+            return Task.FromResult(0);
+        }
+
+        public void Dispose()
+        {
+            RawReceiveStream?.Dispose();
+            RawReceiveStream = null;
+
+            SendStream?.Dispose();
+            SendStream = null;
+
+            ReceiveStream?.Dispose();
+            ReceiveStream = null;
+
+            _socket?.Dispose();
+            _socket = null;
+        }
+
+        private void CreateStreams()
+        {
+            SendStream = _socket.OutputStream.AsStreamForWrite();
+            ReceiveStream = _socket.InputStream.AsStreamForRead();
+            RawReceiveStream = ReceiveStream;
+        }
+
+        private static Certificate LoadCertificate(MqttClientOptions options)
+        {
+            if (options.TlsOptions.Certificates == null || !options.TlsOptions.Certificates.Any())
+            {
+                return null;
+            }
+
+            if (options.TlsOptions.Certificates.Count > 1)
+            {
+                throw new NotSupportedException("Only one client certificate is supported for UWP.");
+            }
+
+            return new Certificate(options.TlsOptions.Certificates.First().AsBuffer());
+        }
+
+        private IEnumerable<ChainValidationResult> ResolveIgnorableServerCertificateErrors()
+        {
+            if (CustomIgnorableServerCertificateErrorsResolver != null)
+            {
+                return CustomIgnorableServerCertificateErrorsResolver(_options);
+            }
+
+            var result = new List<ChainValidationResult>();
+
+            if (_options.TlsOptions.IgnoreCertificateRevocationErrors)
+            {
+                result.Add(ChainValidationResult.RevocationInformationMissing);
+                //_socket.Control.IgnorableServerCertificateErrors.Add(ChainValidationResult.Revoked); Not supported.
+                result.Add(ChainValidationResult.RevocationFailure);
+            }
+
+            if (_options.TlsOptions.IgnoreCertificateChainErrors)
+            {
+                result.Add(ChainValidationResult.IncompleteChain);
+            }
+
+            if (_options.TlsOptions.AllowUntrustedCertificates)
+            {
+                result.Add(ChainValidationResult.Untrusted);
+            }
+
+            return result;
+        }
+    }
+}

Frameworks/MQTTnet.UniversalWindows/Implementations/MqttWebSocketChannel.cs

@@ -0,0 +1,57 @@
+using MQTTnet.Core.Channel;
+using MQTTnet.Core.Client;
+using System;
+using System.IO;
+using System.Net.WebSockets;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Implementations
+{
+    public sealed class MqttWebSocketChannel : IMqttCommunicationChannel, IDisposable
+    {
+        private readonly MqttClientWebSocketOptions _options;
+        private ClientWebSocket _webSocket = new ClientWebSocket();
+
+        public MqttWebSocketChannel(MqttClientWebSocketOptions options)
+        {
+            _options = options ?? throw new ArgumentNullException(nameof(options));
+        }
+
+        public Stream RawReceiveStream { get; private set; }
+        public Stream SendStream => RawReceiveStream;
+        public Stream ReceiveStream => RawReceiveStream;
+
+        public async Task ConnectAsync()
+        {
+            var uri = _options.Uri;
+            if (!uri.StartsWith("ws://", StringComparison.OrdinalIgnoreCase))
+            {
+                uri = "ws://" + uri;
+            }
+
+            _webSocket = new ClientWebSocket();
+            _webSocket.Options.KeepAliveInterval = _options.KeepAlivePeriod;
+            await _webSocket.ConnectAsync(new Uri(uri), CancellationToken.None).ConfigureAwait(false);
+
+            RawReceiveStream = new WebSocketStream(_webSocket);
+        }
+
+        public async Task DisconnectAsync()
+        {
+            RawReceiveStream = null;
+
+            if (_webSocket == null)
+            {
+                return;
+            }
+
+            await _webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, CancellationToken.None).ConfigureAwait(false);
+        }
+
+        public void Dispose()
+        {
+            _webSocket?.Dispose();
+        }
+    }
+}

Frameworks/MQTTnet.UniversalWindows/Implementations/WebSocketStream.cs

@@ -0,0 +1,77 @@
+using System;
+using System.IO;
+using System.Net.WebSockets;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Implementations
+{
+    public class WebSocketStream : Stream
+    {
+        private readonly ClientWebSocket _webSocket;
+
+        public WebSocketStream(ClientWebSocket webSocket)
+        {
+            _webSocket = webSocket;
+        }
+
+        public override void Flush()
+        {
+        }
+
+        public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            var currentOffset = offset;
+            var targetOffset = offset + count;
+            while (_webSocket.State == WebSocketState.Open && currentOffset < targetOffset)
+            {
+                var response = await _webSocket.ReceiveAsync(new ArraySegment<byte>(buffer, currentOffset, count), cancellationToken).ConfigureAwait(false);
+                currentOffset += response.Count;
+                
+                if (response.MessageType == WebSocketMessageType.Close)
+                {
+                    await _webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, cancellationToken).ConfigureAwait(false);
+                }
+            }
+
+            return currentOffset - offset;
+        }
+
+        public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            return _webSocket.SendAsync(new ArraySegment<byte>(buffer, offset, count), WebSocketMessageType.Binary, true, cancellationToken);
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            return ReadAsync(buffer, offset, count).GetAwaiter().GetResult();
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            WriteAsync(buffer, offset, count).GetAwaiter().GetResult();
+        }
+
+        public override bool CanRead => true;
+        public override bool CanSeek => false;
+        public override bool CanWrite => true;
+
+        public override long Length => throw new NotSupportedException();
+
+        public override long Position
+        {
+            get => throw new NotSupportedException();
+            set => throw new NotSupportedException();
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            throw new NotSupportedException();
+        }
+
+        public override void SetLength(long value)
+        {
+            throw new NotSupportedException();
+        }
+    }
+}

Frameworks/MQTTnet.UniversalWindows/MQTTnet.UniversalWindows.csproj

@@ -11,11 +11,12 @@
     <AssemblyName>MQTTnet</AssemblyName>
     <DefaultLanguage>en-US</DefaultLanguage>
     <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
-    <TargetPlatformVersion>10.0.14393.0</TargetPlatformVersion>
+    <TargetPlatformVersion>10.0.15063.0</TargetPlatformVersion>
     <TargetPlatformMinVersion>10.0.10240.0</TargetPlatformMinVersion>
     <MinimumVisualStudioVersion>14</MinimumVisualStudioVersion>
     <FileAlignment>512</FileAlignment>
     <ProjectTypeGuids>{A5A43C5B-DE2A-4C0C-9213-0A381AF9435A};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <RuntimeIdentifiers>win10-arm;win10-arm-aot;win10-x86;win10-x86-aot;win10-x64;win10-x64-aot</RuntimeIdentifiers>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <PlatformTarget>AnyCPU</PlatformTarget>
@@ -26,6 +27,7 @@
     <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <NoWarn>CS1591</NoWarn>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <PlatformTarget>AnyCPU</PlatformTarget>
@@ -35,13 +37,14 @@
     <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <NoWarn>CS1591</NoWarn>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x86'">
     <PlatformTarget>x86</PlatformTarget>
     <DebugSymbols>true</DebugSymbols>
     <OutputPath>bin\x86\Debug\</OutputPath>
     <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <NoWarn>;2008</NoWarn>
+    <NoWarn>;2008,CS1591</NoWarn>
     <DebugType>full</DebugType>
     <PlatformTarget>x86</PlatformTarget>
     <UseVSHostingProcess>false</UseVSHostingProcess>
@@ -52,18 +55,19 @@
     <OutputPath>bin\x86\Release\</OutputPath>
     <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
     <Optimize>true</Optimize>
-    <NoWarn>;2008</NoWarn>
+    <NoWarn>;2008,CS1591</NoWarn>
     <DebugType>pdbonly</DebugType>
     <PlatformTarget>x86</PlatformTarget>
     <UseVSHostingProcess>false</UseVSHostingProcess>
     <ErrorReport>prompt</ErrorReport>
+    <DocumentationFile>bin\x86\Release\MQTTnet.XML</DocumentationFile>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|ARM'">
     <PlatformTarget>ARM</PlatformTarget>
     <DebugSymbols>true</DebugSymbols>
     <OutputPath>bin\ARM\Debug\</OutputPath>
     <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <NoWarn>;2008</NoWarn>
+    <NoWarn>;2008,CS1591</NoWarn>
     <DebugType>full</DebugType>
     <PlatformTarget>ARM</PlatformTarget>
     <UseVSHostingProcess>false</UseVSHostingProcess>
@@ -74,18 +78,19 @@
     <OutputPath>bin\ARM\Release\</OutputPath>
     <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
     <Optimize>true</Optimize>
-    <NoWarn>;2008</NoWarn>
+    <NoWarn>;2008,CS1591</NoWarn>
     <DebugType>pdbonly</DebugType>
     <PlatformTarget>ARM</PlatformTarget>
     <UseVSHostingProcess>false</UseVSHostingProcess>
     <ErrorReport>prompt</ErrorReport>
+    <DocumentationFile>bin\ARM\Release\MQTTnet.XML</DocumentationFile>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x64'">
     <PlatformTarget>x64</PlatformTarget>
     <DebugSymbols>true</DebugSymbols>
     <OutputPath>bin\x64\Debug\</OutputPath>
     <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <NoWarn>;2008</NoWarn>
+    <NoWarn>;2008,CS1591</NoWarn>
     <DebugType>full</DebugType>
     <PlatformTarget>x64</PlatformTarget>
     <UseVSHostingProcess>false</UseVSHostingProcess>
@@ -96,33 +101,89 @@
     <OutputPath>bin\x64\Release\</OutputPath>
     <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
     <Optimize>true</Optimize>
-    <NoWarn>;2008</NoWarn>
+    <NoWarn>;2008,CS1591</NoWarn>
     <DebugType>pdbonly</DebugType>
     <PlatformTarget>x64</PlatformTarget>
     <UseVSHostingProcess>false</UseVSHostingProcess>
     <ErrorReport>prompt</ErrorReport>
+    <GenerateLibraryLayout>false</GenerateLibraryLayout>
+    <DocumentationFile>bin\x64\Release\MQTTnet.XML</DocumentationFile>
   </PropertyGroup>
   <ItemGroup>
-    <!-- A reference to the entire .Net Framework and Windows SDK are automatically included -->
-    <None Include="project.json" />
-  </ItemGroup>
-  <ItemGroup>
+    <Compile Include="Implementations\MqttCommunicationAdapterFactory.cs" />
+    <Compile Include="Implementations\MqttWebSocketChannel.cs" />
     <Compile Include="MqttClientFactory.cs" />
-    <Compile Include="MqttServerAdapter.cs" />
+    <Compile Include="Implementations\MqttServerAdapter.cs" />
+    <Compile Include="Implementations\MqttTcpChannel.cs" />
     <Compile Include="MqttServerFactory.cs" />
-    <Compile Include="MqttTcpChannel.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="Implementations\WebSocketStream.cs" />
     <EmbeddedResource Include="Properties\MQTTnet.Universal.rd.xml" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\MQTTnet.Core\MQTTnet.Core.csproj">
-      <Project>{99C884F3-B4B9-417D-AA92-DC7DD1C4CFEE}</Project>
+      <Project>{2ecb99e4-72d0-4c23-99ba-93d511d3967d}</Project>
       <Name>MQTTnet.Core</Name>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NETCore.UniversalWindowsPlatform">
+      <Version>5.4.0</Version>
+    </PackageReference>
+  </ItemGroup>
   <PropertyGroup Condition=" '$(VisualStudioVersion)' == '' or '$(VisualStudioVersion)' &lt; '14.0' ">
     <VisualStudioVersion>14.0</VisualStudioVersion>
   </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Any CPU|AnyCPU'">
+    <OutputPath>bin\Any CPU\</OutputPath>
+    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
+    <Optimize>true</Optimize>
+    <NoStdLib>true</NoStdLib>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Any CPU|x86'">
+    <OutputPath>bin\x86\Any CPU\</OutputPath>
+    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
+    <DocumentationFile>bin\x86\Release\MQTTnet.XML</DocumentationFile>
+    <Optimize>true</Optimize>
+    <NoWarn>;2008</NoWarn>
+    <NoStdLib>true</NoStdLib>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>x86</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Any CPU|ARM'">
+    <OutputPath>bin\ARM\Any CPU\</OutputPath>
+    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
+    <DocumentationFile>bin\ARM\Release\MQTTnet.XML</DocumentationFile>
+    <Optimize>true</Optimize>
+    <NoWarn>;2008</NoWarn>
+    <NoStdLib>true</NoStdLib>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>ARM</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Any CPU|x64'">
+    <OutputPath>bin\x64\Any CPU\</OutputPath>
+    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
+    <DocumentationFile>bin\x64\Release\MQTTnet.XML</DocumentationFile>
+    <Optimize>true</Optimize>
+    <NoWarn>;2008</NoWarn>
+    <NoStdLib>true</NoStdLib>
+    <DebugType>pdbonly</DebugType>
+    <PlatformTarget>x64</PlatformTarget>
+    <UseVSHostingProcess>false</UseVSHostingProcess>
+    <ErrorReport>prompt</ErrorReport>
+    <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
+  </PropertyGroup>
   <Import Project="$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.

Frameworks/MQTTnet.UniversalWindows/MqttClientFactory.cs

@@ -1,17 +1,13 @@
-using System;
-using MQTTnet.Core.Adapter;
-using MQTTnet.Core.Client;
-using MQTTnet.Core.Serializer;
+using MQTTnet.Core.Client;
+using MQTTnet.Implementations;
 
 namespace MQTTnet
 {
-    public class MqttClientFactory
+    public class MqttClientFactory : IMqttClientFactory
     {
-        public MqttClient CreateMqttClient(MqttClientOptions options)
+        public IMqttClient CreateMqttClient()
         {
-            if (options == null) throw new ArgumentNullException(nameof(options));
-
-            return new MqttClient(options, new MqttChannelCommunicationAdapter(new MqttTcpChannel(), new DefaultMqttV311PacketSerializer()));
+            return new MqttClient(new MqttCommunicationAdapterFactory());
         }
     }
-}
+}

Frameworks/MQTTnet.UniversalWindows/MqttServerAdapter.cs

@@ -1,54 +0,0 @@
-using System;
-using System.Threading;
-using Windows.Networking.Sockets;
-using MQTTnet.Core.Adapter;
-using MQTTnet.Core.Serializer;
-using MQTTnet.Core.Server;
-
-namespace MQTTnet
-{
-    public sealed class MqttServerAdapter : IMqttServerAdapter, IDisposable
-    {
-        private CancellationTokenSource _cancellationTokenSource;
-        private StreamSocketListener _socket;
-
-        public event EventHandler<MqttClientConnectedEventArgs> ClientConnected;
-
-        public void Start(MqttServerOptions options)
-        {
-            if (_socket != null) throw new InvalidOperationException("Server is already started.");
-
-            _cancellationTokenSource = new CancellationTokenSource();
-
-            _socket = new StreamSocketListener();
-            _socket.BindServiceNameAsync(options.Port.ToString()).AsTask().Wait();
-            _socket.ConnectionReceived += ConnectionReceived;
-        }
-
-        private void ConnectionReceived(StreamSocketListener sender, StreamSocketListenerConnectionReceivedEventArgs args)
-        {
-            var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(args.Socket), new DefaultMqttV311PacketSerializer());
-
-            var identifier = $"{args.Socket.Information.RemoteAddress}:{args.Socket.Information.RemotePort}";
-            ClientConnected?.Invoke(this, new MqttClientConnectedEventArgs(identifier, clientAdapter));
-        }
-
-        public void Stop()
-        {
-            _cancellationTokenSource?.Dispose();
-
-            if (_socket != null)
-            {
-                _socket.ConnectionReceived -= ConnectionReceived;
-            }
-
-            _socket?.Dispose();
-            _socket = null;
-        }
-
-        public void Dispose()
-        {
-            Stop();
-        }
-    }
-}

Frameworks/MQTTnet.UniversalWindows/MqttServerFactory.cs

@@ -1,15 +1,18 @@
 using System;
+using System.Collections.Generic;
+using MQTTnet.Core.Adapter;
 using MQTTnet.Core.Server;
+using MQTTnet.Implementations;
 
 namespace MQTTnet
 {
-    public class MqttServerFactory
+    public class MqttServerFactory : IMqttServerFactory
     {
-        public MqttServer CreateMqttServer(MqttServerOptions options)
+        public IMqttServer CreateMqttServer(MqttServerOptions options)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 
-            return new MqttServer(options, new MqttServerAdapter());
+            return new MqttServer(options, new List<IMqttServerAdapter> { new MqttServerAdapter() });
         }
     }
 }

Frameworks/MQTTnet.UniversalWindows/MqttTcpChannel.cs

@@ -1,62 +0,0 @@
-using System;
-using System.Runtime.InteropServices.WindowsRuntime;
-using System.Threading.Tasks;
-using Windows.Networking;
-using Windows.Networking.Sockets;
-using Windows.Storage.Streams;
-using MQTTnet.Core.Channel;
-using MQTTnet.Core.Client;
-using Buffer = Windows.Storage.Streams.Buffer;
-
-namespace MQTTnet
-{
-    public sealed class MqttTcpChannel : IMqttCommunicationChannel, IDisposable
-    {
-        private readonly StreamSocket _socket;
-
-        public MqttTcpChannel()
-        {
-            _socket = new StreamSocket();
-        }
-
-        public MqttTcpChannel(StreamSocket socket)
-        {
-            _socket = socket ?? throw new ArgumentNullException(nameof(socket));
-        }
-
-        public async Task ConnectAsync(MqttClientOptions options)
-        {
-            if (options == null) throw new ArgumentNullException(nameof(options));
-
-            await _socket.ConnectAsync(new HostName(options.Server), options.Port.ToString());
-        }
-
-        public async Task DisconnectAsync()
-        {
-            await _socket.CancelIOAsync();
-            _socket.Dispose();
-        }
-
-        public async Task WriteAsync(byte[] buffer)
-        {
-            if (buffer == null) throw new ArgumentNullException(nameof(buffer));
-
-            await _socket.OutputStream.WriteAsync(buffer.AsBuffer());
-            await _socket.OutputStream.FlushAsync();
-        }
-
-        public async Task ReadAsync(byte[] buffer)
-        {
-            var buffer2 = new Buffer((uint)buffer.Length);
-            await _socket.InputStream.ReadAsync(buffer2, (uint)buffer.Length, InputStreamOptions.None);
-
-            var array2 = buffer2.ToArray();
-            Array.Copy(array2, buffer, array2.Length);
-        }
-
-        public void Dispose()
-        {
-            _socket?.Dispose();
-        }
-    }
-}

Frameworks/MQTTnet.UniversalWindows/Properties/AssemblyInfo.cs

@@ -10,5 +10,5 @@ using System.Runtime.InteropServices;
 [assembly: AssemblyTrademark("")]
 [assembly: AssemblyCulture("")]
 [assembly: ComVisible(false)]
-[assembly: AssemblyVersion("2.1.0.4")]
-[assembly: AssemblyFileVersion("2.1.0.4")]
+[assembly: AssemblyVersion("2.4.0.0")]
+[assembly: AssemblyFileVersion("2.4.0.0")]

Frameworks/MQTTnet.UniversalWindows/Properties/MQTTnet.Universal.rd.xml

@@ -1,33 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!--
-    This file contains Runtime Directives, specifications about types your application accesses
-    through reflection and other dynamic code patterns. Runtime Directives are used to control the
-    .NET Native optimizer and ensure that it does not remove code accessed by your library. If your
-    library does not do any reflection, then you generally do not need to edit this file. However,
-    if your library reflects over types, especially types passed to it or derived from its types,
-    then you should write Runtime Directives.
-
-    The most common use of reflection in libraries is to discover information about types passed
-    to the library. Runtime Directives have three ways to express requirements on types passed to
-    your library.
-
-    1.  Parameter, GenericParameter, TypeParameter, TypeEnumerableParameter
-        Use these directives to reflect over types passed as a parameter.
-
-    2.  SubTypes
-        Use a SubTypes directive to reflect over types derived from another type.
-
-    3.  AttributeImplies
-        Use an AttributeImplies directive to indicate that your library needs to reflect over
-        types or methods decorated with an attribute.
-
-    For more information on writing Runtime Directives for libraries, please visit
-    http://go.microsoft.com/fwlink/?LinkID=391919
--->
 <Directives xmlns="http://schemas.microsoft.com/netfx/2013/01/metadata">
   <Library Name="MQTTnet.Universal">
-
-  	<!-- add directives for your library here -->
-
   </Library>
 </Directives>

Frameworks/MQTTnet.UniversalWindows/project.json

@@ -1,16 +0,0 @@
-{
-  "dependencies": {
-    "Microsoft.NETCore.UniversalWindowsPlatform": "5.1.0"
-  },
-  "frameworks": {
-    "uap10.0": {}
-  },
-  "runtimes": {
-    "win10-arm": {},
-    "win10-arm-aot": {},
-    "win10-x86": {},
-    "win10-x86-aot": {},
-    "win10-x64": {},
-    "win10-x64-aot": {}
-  }
-}

MQTTnet.Core/Adapter/IMqttCommunicationAdapter.cs

@@ -1,18 +1,22 @@
 using System;
+using System.Collections.Generic;
+using System.Threading;
 using System.Threading.Tasks;
-using MQTTnet.Core.Client;
 using MQTTnet.Core.Packets;
+using MQTTnet.Core.Serializer;
 
 namespace MQTTnet.Core.Adapter
 {
     public interface IMqttCommunicationAdapter
     {
-        Task ConnectAsync(MqttClientOptions options, TimeSpan timeout);
+        IMqttPacketSerializer PacketSerializer { get; }
 
-        Task DisconnectAsync();
+        Task ConnectAsync(TimeSpan timeout);
 
-        Task SendPacketAsync(MqttBasePacket packet, TimeSpan timeout);
+        Task DisconnectAsync(TimeSpan timeout);
 
-        Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout);
+        Task SendPacketsAsync(TimeSpan timeout, CancellationToken cancellationToken, IEnumerable<MqttBasePacket> packets);
+
+        Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout, CancellationToken cancellationToken);
     }
 }

MQTTnet.Core/Adapter/IMqttServerAdapter.cs

@@ -1,14 +1,14 @@
 using System;
+using System.Threading.Tasks;
 using MQTTnet.Core.Server;
 
 namespace MQTTnet.Core.Adapter
 {
     public interface IMqttServerAdapter
     {
-        event EventHandler<MqttClientConnectedEventArgs> ClientConnected;
+        event Action<IMqttCommunicationAdapter> ClientAccepted;
 
-        void Start(MqttServerOptions options);
-
-        void Stop();
+        Task StartAsync(MqttServerOptions options);
+        Task StopAsync();
     }
 }

MQTTnet.Core/Adapter/MqttChannelCommunicationAdapter.cs

@@ -1,9 +1,12 @@
 using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Core.Channel;
-using MQTTnet.Core.Client;
 using MQTTnet.Core.Diagnostics;
 using MQTTnet.Core.Exceptions;
+using MQTTnet.Core.Internal;
 using MQTTnet.Core.Packets;
 using MQTTnet.Core.Serializer;
 
@@ -11,78 +14,196 @@ namespace MQTTnet.Core.Adapter
 {
     public class MqttChannelCommunicationAdapter : IMqttCommunicationAdapter
     {
-        private readonly IMqttPacketSerializer _serializer;
         private readonly IMqttCommunicationChannel _channel;
+        private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1, 1);
 
         public MqttChannelCommunicationAdapter(IMqttCommunicationChannel channel, IMqttPacketSerializer serializer)
         {
             _channel = channel ?? throw new ArgumentNullException(nameof(channel));
-            _serializer = serializer ?? throw new ArgumentNullException(nameof(serializer));
+            PacketSerializer = serializer ?? throw new ArgumentNullException(nameof(serializer));
         }
 
-        public async Task ConnectAsync(MqttClientOptions options, TimeSpan timeout)
-        {
-            var task = _channel.ConnectAsync(options);
-            if (await Task.WhenAny(Task.Delay(timeout), task) != task)
-            {
-                throw new MqttCommunicationTimedOutException();
-            }
-        }
+        public IMqttPacketSerializer PacketSerializer { get; }
 
-        public async Task DisconnectAsync()
+        public async Task ConnectAsync(TimeSpan timeout)
         {
-            await _channel.DisconnectAsync();
-        }
-
-        public async Task SendPacketAsync(MqttBasePacket packet, TimeSpan timeout)
-        {
-            MqttTrace.Information(nameof(MqttChannelCommunicationAdapter), $"TX >>> {packet} [Timeout={timeout}]");
-
-            bool hasTimeout;
             try
             {
-                var task = _serializer.SerializeAsync(packet, _channel);
-                hasTimeout = await Task.WhenAny(Task.Delay(timeout), task) != task;
+                await _channel.ConnectAsync().TimeoutAfter(timeout).ConfigureAwait(false);
+            }
+            catch (TaskCanceledException)
+            {
+                throw;
+            }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
+            catch (MqttCommunicationTimedOutException)
+            {
+                throw;
+            }
+            catch (MqttCommunicationException)
+            {
+                throw;
             }
             catch (Exception exception)
             {
                 throw new MqttCommunicationException(exception);
             }
+        }
 
-            if (hasTimeout)
+        public async Task DisconnectAsync(TimeSpan timeout)
+        {
+            try
             {
-                throw new MqttCommunicationTimedOutException();
+                await _channel.DisconnectAsync().TimeoutAfter(timeout).ConfigureAwait(false);
+            }
+            catch (TaskCanceledException)
+            {
+                throw;
+            }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
+            catch (MqttCommunicationTimedOutException)
+            {
+                throw;
+            }
+            catch (MqttCommunicationException)
+            {
+                throw;
+            }
+            catch (Exception exception)
+            {
+                throw new MqttCommunicationException(exception);
             }
         }
 
-        public async Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout)
+        public async Task SendPacketsAsync(TimeSpan timeout, CancellationToken cancellationToken, IEnumerable<MqttBasePacket> packets)
         {
-            MqttBasePacket packet;
-            if (timeout > TimeSpan.Zero)
-            {
-                var workerTask = _serializer.DeserializeAsync(_channel);
-                var timeoutTask = Task.Delay(timeout);
-                var hasTimeout = Task.WhenAny(timeoutTask, workerTask) == timeoutTask;
+            await _semaphore.WaitAsync(cancellationToken);
 
-                if (hasTimeout)
+            try
+            {
+                foreach (var packet in packets)
                 {
-                    throw new MqttCommunicationTimedOutException();
+                    if (packet == null)
+                    {
+                        continue;
+                    }
+
+                    MqttNetTrace.Information(nameof(MqttChannelCommunicationAdapter), "TX >>> {0} [Timeout={1}]", packet, timeout);
+
+                    var writeBuffer = PacketSerializer.Serialize(packet);
+                    await _channel.SendStream.WriteAsync(writeBuffer, 0, writeBuffer.Length, cancellationToken).ConfigureAwait(false);
                 }
 
-                packet = workerTask.Result;
+                if (timeout > TimeSpan.Zero)
+                {
+                    await _channel.SendStream.FlushAsync(cancellationToken).TimeoutAfter(timeout).ConfigureAwait(false);
+                }
+                else
+                {
+                    await _channel.SendStream.FlushAsync(cancellationToken).ConfigureAwait(false);
+                }
             }
-            else
+            catch (TaskCanceledException)
             {
-                packet = await _serializer.DeserializeAsync(_channel);
+                throw;
+            }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
+            catch (MqttCommunicationTimedOutException)
+            {
+                throw;
+            }
+            catch (MqttCommunicationException)
+            {
+                throw;
+            }
+            catch (Exception exception)
+            {
+                throw new MqttCommunicationException(exception);
+            }
+            finally
+            {
+                _semaphore.Release();
+            }
+        }
+
+        public async Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout, CancellationToken cancellationToken)
+        {
+            try
+            {
+                ReceivedMqttPacket receivedMqttPacket;
+                if (timeout > TimeSpan.Zero)
+                {
+                    receivedMqttPacket = await ReceiveAsync(_channel.RawReceiveStream, cancellationToken).TimeoutAfter(timeout).ConfigureAwait(false);
+                }
+                else
+                {
+                    receivedMqttPacket = await ReceiveAsync(_channel.ReceiveStream, cancellationToken).ConfigureAwait(false);
+                }
+
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    throw new TaskCanceledException();
+                }
+
+                var packet = PacketSerializer.Deserialize(receivedMqttPacket);
+                if (packet == null)
+                {
+                    throw new MqttProtocolViolationException("Received malformed packet.");
+                }
+
+                MqttNetTrace.Information(nameof(MqttChannelCommunicationAdapter), "RX <<< {0}", packet);
+                return packet;
+            }
+            catch (TaskCanceledException)
+            {
+                throw;
+            }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
+            catch (MqttCommunicationTimedOutException)
+            {
+                throw;
+            }
+            catch (MqttCommunicationException)
+            {
+                throw;
+            }
+            catch (Exception exception)
+            {
+                throw new MqttCommunicationException(exception);
+            }
+        }
+
+        private static async Task<ReceivedMqttPacket> ReceiveAsync(Stream stream, CancellationToken cancellationToken)
+        {
+            var header = MqttPacketReader.ReadHeaderFromSource(stream, cancellationToken);
+
+            if (header.BodyLength == 0)
+            {
+                return new ReceivedMqttPacket(header, new MemoryStream(0));
             }
 
-            if (packet == null)
-            {
-                throw new MqttProtocolViolationException("Received malformed packet.");
-            }
+            var body = new byte[header.BodyLength];
 
-            MqttTrace.Information(nameof(MqttChannelCommunicationAdapter), $"RX <<< {packet}");
-            return packet;
+            var offset = 0;
+            do
+            {
+                var readBytesCount = await stream.ReadAsync(body, offset, body.Length - offset, cancellationToken).ConfigureAwait(false);
+                offset += readBytesCount;
+            } while (offset < header.BodyLength);
+
+            return new ReceivedMqttPacket(header, new MemoryStream(body, 0, body.Length));
         }
     }
-}
+}

MQTTnet.Core/Adapter/MqttClientConnectedEventArgs.cs

@@ -1,17 +1,15 @@
-using System;
+using MQTTnet.Core.Server;
+using System;
 
 namespace MQTTnet.Core.Adapter
 {
     public class MqttClientConnectedEventArgs : EventArgs
     {
-        public MqttClientConnectedEventArgs(string identifier, IMqttCommunicationAdapter clientAdapter)
+        public MqttClientConnectedEventArgs(ConnectedMqttClient client)
         {
-            Identifier = identifier ?? throw new ArgumentNullException(nameof(identifier));
-            ClientAdapter = clientAdapter ?? throw new ArgumentNullException(nameof(clientAdapter));
+            Client = client ?? throw new ArgumentNullException(nameof(client));
         }
 
-        public string Identifier { get; }
-
-        public IMqttCommunicationAdapter ClientAdapter { get; }
+        public ConnectedMqttClient Client { get; }
     }
 }

MQTTnet.Core/Adapter/MqttClientDisconnectedEventArgs.cs

@@ -0,0 +1,15 @@
+using MQTTnet.Core.Server;
+using System;
+
+namespace MQTTnet.Core.Adapter
+{
+    public class MqttClientDisconnectedEventArgs : EventArgs
+    {
+        public MqttClientDisconnectedEventArgs(ConnectedMqttClient client)
+        {
+            Client = client ?? throw new ArgumentNullException(nameof(client));
+        }
+        
+        public ConnectedMqttClient Client { get; }
+    }
+}

MQTTnet.Core/Adapter/MqttCommunicationAdapterExtensions.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Core.Packets;
+
+namespace MQTTnet.Core.Adapter
+{
+    public static class MqttCommunicationAdapterExtensions
+    {
+        public static Task SendPacketsAsync(this IMqttCommunicationAdapter adapter, TimeSpan timeout, CancellationToken cancellationToken, params MqttBasePacket[] packets)
+        {
+            return adapter.SendPacketsAsync(timeout, cancellationToken, packets);
+        }
+    }
+}

MQTTnet.Core/Adapter/MqttConnectingFailedException.cs

@@ -5,7 +5,7 @@ namespace MQTTnet.Core.Adapter
 {
     public class MqttConnectingFailedException : MqttCommunicationException
     {
-        public MqttConnectingFailedException(MqttConnectReturnCode returnCode) 
+        public MqttConnectingFailedException(MqttConnectReturnCode returnCode)
             : base($"Connecting with MQTT server failed ({returnCode}).")
         {
             ReturnCode = returnCode;

MQTTnet.Core/Adapter/ReceivedMqttPacket.cs

@@ -0,0 +1,19 @@
+using System;
+using System.IO;
+using MQTTnet.Core.Packets;
+
+namespace MQTTnet.Core.Adapter
+{
+    public class ReceivedMqttPacket
+    {
+        public ReceivedMqttPacket(MqttPacketHeader header, MemoryStream body)
+        {
+            Header = header ?? throw new ArgumentNullException(nameof(header));
+            Body = body ?? throw new ArgumentNullException(nameof(body));
+        }
+
+        public MqttPacketHeader Header { get; }
+
+        public MemoryStream Body { get; }
+    }
+}

MQTTnet.Core/Channel/IMqttCommunicationChannel.cs

@@ -1,16 +1,15 @@
 using System.Threading.Tasks;
-using MQTTnet.Core.Client;
+using System.IO;
 
 namespace MQTTnet.Core.Channel
 {
     public interface IMqttCommunicationChannel
     {
-        Task ConnectAsync(MqttClientOptions options);
+        Stream SendStream { get; }
+        Stream ReceiveStream { get; }
+        Stream RawReceiveStream { get; }
 
+        Task ConnectAsync();
         Task DisconnectAsync();
-
-        Task WriteAsync(byte[] buffer);
-
-        Task ReadAsync(byte[] buffer);
     }
 }

MQTTnet.Core/Client/IMqttClient.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using MQTTnet.Core.Packets;
+
+namespace MQTTnet.Core.Client
+{
+    public interface IMqttClient
+    {
+        bool IsConnected { get; }
+
+        event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
+        event EventHandler Connected;
+        event EventHandler Disconnected;
+
+        Task ConnectAsync(MqttClientOptions options);
+        Task DisconnectAsync();
+
+        Task<IList<MqttSubscribeResult>> SubscribeAsync(IEnumerable<TopicFilter> topicFilters);
+        Task UnsubscribeAsync(IEnumerable<string> topicFilters);
+
+        Task PublishAsync(IEnumerable<MqttApplicationMessage> applicationMessages);
+    }
+}

MQTTnet.Core/Client/IMqttClientFactory.cs

@@ -0,0 +1,7 @@
+namespace MQTTnet.Core.Client
+{
+    public interface IMqttClientFactory
+    {
+        IMqttClient CreateMqttClient();
+    }
+}

MQTTnet.Core/Client/IMqttCommunicationAdapterFactory.cs

@@ -0,0 +1,9 @@
+using MQTTnet.Core.Adapter;
+
+namespace MQTTnet.Core.Client
+{
+    public interface IMqttCommunicationAdapterFactory
+    {
+        IMqttCommunicationAdapter CreateMqttCommunicationAdapter(MqttClientOptions options);
+    }
+}

MQTTnet.Core/Client/MqttApplicationMessageReceivedEventArgs.cs

@@ -1,8 +1,8 @@
 using System;
 
-namespace MQTTnet.Core
+namespace MQTTnet.Core.Client
 {
-    public class MqttApplicationMessageReceivedEventArgs : EventArgs
+    public sealed class MqttApplicationMessageReceivedEventArgs : EventArgs
     {
         public MqttApplicationMessageReceivedEventArgs(MqttApplicationMessage applicationMessage)
         {

MQTTnet.Core/Client/MqttClient.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
@@ -13,159 +12,201 @@ using MQTTnet.Core.Protocol;
 
 namespace MQTTnet.Core.Client
 {
-    public class MqttClient
+    public class MqttClient : IMqttClient
     {
-        private readonly ConcurrentDictionary<ushort, MqttPublishPacket> _pendingExactlyOncePublishPackets = new ConcurrentDictionary<ushort, MqttPublishPacket>();
-        private readonly HashSet<ushort> _processedPublishPackets = new HashSet<ushort>();
-
+        private readonly HashSet<ushort> _unacknowledgedPublishPackets = new HashSet<ushort>();
         private readonly MqttPacketDispatcher _packetDispatcher = new MqttPacketDispatcher();
-        private readonly MqttClientOptions _options;
-        private readonly IMqttCommunicationAdapter _adapter;
+        private readonly IMqttCommunicationAdapterFactory _communicationChannelFactory;
 
+        private MqttClientOptions _options;
+        private bool _isReceivingPackets;
         private int _latestPacketIdentifier;
         private CancellationTokenSource _cancellationTokenSource;
+        private IMqttCommunicationAdapter _adapter;
 
-        public MqttClient(MqttClientOptions options, IMqttCommunicationAdapter adapter)
+        public MqttClient(IMqttCommunicationAdapterFactory communicationChannelFactory)
         {
-            _options = options ?? throw new ArgumentNullException(nameof(options));
-            _adapter = adapter ?? throw new ArgumentNullException(nameof(adapter));
+            _communicationChannelFactory = communicationChannelFactory ?? throw new ArgumentNullException(nameof(communicationChannelFactory));
         }
 
         public event EventHandler Connected;
-
         public event EventHandler Disconnected;
-
         public event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
 
-        public bool IsConnected { get; private set; }
+        public bool IsConnected => _cancellationTokenSource != null && !_cancellationTokenSource.IsCancellationRequested;
 
-        public async Task ConnectAsync(MqttApplicationMessage willApplicationMessage = null)
+        public async Task ConnectAsync(MqttClientOptions options)
         {
-            MqttTrace.Verbose(nameof(MqttClient), "Trying to connect.");
+            if (options == null) throw new ArgumentNullException(nameof(options));
 
-            if (IsConnected)
+            ThrowIfConnected("It is not allowed to connect with a server after the connection is established.");
+
+            try
             {
-                throw new MqttProtocolViolationException("It is not allowed to connect with a server after the connection is established.");
+                _options = options;
+                _cancellationTokenSource = new CancellationTokenSource();
+                _latestPacketIdentifier = 0;
+                _packetDispatcher.Reset();
+
+                _adapter = _communicationChannelFactory.CreateMqttCommunicationAdapter(options);
+                
+                MqttNetTrace.Verbose(nameof(MqttClient), "Trying to connect with server.");
+                await _adapter.ConnectAsync(_options.DefaultCommunicationTimeout).ConfigureAwait(false);
+                MqttNetTrace.Verbose(nameof(MqttClient), "Connection with server established.");
+
+                await SetupIncomingPacketProcessingAsync();
+                await AuthenticateAsync(options.WillMessage);
+
+                MqttNetTrace.Verbose(nameof(MqttClient), "MQTT connection with server established.");
+
+                if (_options.KeepAlivePeriod != TimeSpan.Zero)
+                {
+                    StartSendKeepAliveMessages(_cancellationTokenSource.Token);
+                }
+
+                Connected?.Invoke(this, EventArgs.Empty);
             }
-
-            var connectPacket = new MqttConnectPacket
+            catch (Exception)
             {
-                ClientId = _options.ClientId,
-                Username = _options.UserName,
-                Password = _options.Password,
-                KeepAlivePeriod = (ushort)_options.KeepAlivePeriod.TotalSeconds,
-                WillMessage = willApplicationMessage
-            };
-
-            await _adapter.ConnectAsync(_options, _options.DefaultCommunicationTimeout);
-            MqttTrace.Verbose(nameof(MqttClient), "Connection with server established.");
-
-            _cancellationTokenSource = new CancellationTokenSource();
-            _latestPacketIdentifier = 0;
-            _processedPublishPackets.Clear();
-            _packetDispatcher.Reset();
-            IsConnected = true;
-
-            Task.Run(async () => await ReceivePackets(_cancellationTokenSource.Token), _cancellationTokenSource.Token).Forget();
-
-            var response = await SendAndReceiveAsync<MqttConnAckPacket>(connectPacket);
-            if (response.ConnectReturnCode != MqttConnectReturnCode.ConnectionAccepted)
-            {
-                throw new MqttConnectingFailedException(response.ConnectReturnCode);
+                await DisconnectInternalAsync().ConfigureAwait(false);
+                throw;
             }
-
-            if (_options.KeepAlivePeriod != TimeSpan.Zero)
-            {
-                Task.Run(async () => await SendKeepAliveMessagesAsync(_cancellationTokenSource.Token), _cancellationTokenSource.Token).Forget();
-            }
-
-            Connected?.Invoke(this, EventArgs.Empty);
         }
 
         public async Task DisconnectAsync()
         {
-            await SendAsync(new MqttDisconnectPacket());
-            await DisconnectInternalAsync();
+            if (!IsConnected)
+            {
+                return;
+            }
+
+            try
+            {
+                await SendAsync(new MqttDisconnectPacket()).ConfigureAwait(false);
+            }
+            finally
+            {
+                await DisconnectInternalAsync().ConfigureAwait(false);
+            }
         }
 
-        public async Task<IList<MqttSubscribeResult>> SubscribeAsync(params TopicFilter[] topicFilters)
+        public async Task<IList<MqttSubscribeResult>> SubscribeAsync(IEnumerable<TopicFilter> topicFilters)
         {
             if (topicFilters == null) throw new ArgumentNullException(nameof(topicFilters));
 
-            return await SubscribeAsync(topicFilters.ToList());
-        }
-
-        public async Task<IList<MqttSubscribeResult>> SubscribeAsync(IList<TopicFilter> topicFilters)
-        {
-            if (topicFilters == null) throw new ArgumentNullException(nameof(topicFilters));
-            if (!topicFilters.Any()) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.8.3-3].");
             ThrowIfNotConnected();
 
             var subscribePacket = new MqttSubscribePacket
             {
                 PacketIdentifier = GetNewPacketIdentifier(),
-                TopicFilters = topicFilters
+                TopicFilters = topicFilters.ToList()
             };
 
-            var response = await SendAndReceiveAsync<MqttSubAckPacket>(subscribePacket);
+            var response = await SendAndReceiveAsync<MqttSubAckPacket>(subscribePacket).ConfigureAwait(false);
 
-            if (response.SubscribeReturnCodes.Count != topicFilters.Count)
+            if (response.SubscribeReturnCodes.Count != subscribePacket.TopicFilters.Count)
             {
                 throw new MqttProtocolViolationException("The return codes are not matching the topic filters [MQTT-3.9.3-1].");
             }
 
-            var result = new List<MqttSubscribeResult>();
-            for (var i = 0; i < topicFilters.Count; i++)
-            {
-                result.Add(new MqttSubscribeResult(topicFilters[i], response.SubscribeReturnCodes[i]));
-            }
-
-            return result;
+            return subscribePacket.TopicFilters.Select((t, i) => new MqttSubscribeResult(t, response.SubscribeReturnCodes[i])).ToList();
         }
 
-        public async Task Unsubscribe(params string[] topicFilters)
+        public async Task UnsubscribeAsync(IEnumerable<string> topicFilters)
         {
             if (topicFilters == null) throw new ArgumentNullException(nameof(topicFilters));
 
-            await Unsubscribe(topicFilters.ToList());
-        }
-
-        public async Task Unsubscribe(IList<string> topicFilters)
-        {
-            if (topicFilters == null) throw new ArgumentNullException(nameof(topicFilters));
-            if (!topicFilters.Any()) throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.10.3-2].");
             ThrowIfNotConnected();
 
             var unsubscribePacket = new MqttUnsubscribePacket
             {
                 PacketIdentifier = GetNewPacketIdentifier(),
-                TopicFilters = topicFilters
+                TopicFilters = topicFilters.ToList()
             };
 
             await SendAndReceiveAsync<MqttUnsubAckPacket>(unsubscribePacket);
         }
 
-        public async Task PublishAsync(MqttApplicationMessage applicationMessage)
+        public async Task PublishAsync(IEnumerable<MqttApplicationMessage> applicationMessages)
         {
-            if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
             ThrowIfNotConnected();
 
-            var publishPacket = applicationMessage.ToPublishPacket();
+            var publishPackets = applicationMessages.Select(m => m.ToPublishPacket());
 
-            if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtMostOnce)
+            foreach (var qosGroup in publishPackets.GroupBy(p => p.QualityOfServiceLevel))
             {
-                await SendAsync(publishPacket);
+                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.DefaultCommunicationTimeout, _cancellationTokenSource.Token, qosPackets);
+                            break;
+                        }
+                    case MqttQualityOfServiceLevel.AtLeastOnce:
+                        {
+                            foreach (var publishPacket in qosPackets)
+                            {
+                                publishPacket.PacketIdentifier = GetNewPacketIdentifier();
+                                await SendAndReceiveAsync<MqttPubAckPacket>(publishPacket);
+                            }
+
+                            break;
+                        }
+                    case MqttQualityOfServiceLevel.ExactlyOnce:
+                        {
+                            foreach (var publishPacket in qosPackets)
+                            {
+                                publishPacket.PacketIdentifier = GetNewPacketIdentifier();
+                                var pubRecPacket = await SendAndReceiveAsync<MqttPubRecPacket>(publishPacket).ConfigureAwait(false);
+                                await SendAndReceiveAsync<MqttPubCompPacket>(pubRecPacket.CreateResponse<MqttPubRelPacket>()).ConfigureAwait(false);
+                            }
+
+                            break;
+                        }
+                    default:
+                        {
+                            throw new InvalidOperationException();
+                        }
+                }
             }
-            else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtLeastOnce)
+        }
+
+        private async Task AuthenticateAsync(MqttApplicationMessage willApplicationMessage)
+        {
+            var connectPacket = new MqttConnectPacket
             {
-                publishPacket.PacketIdentifier = GetNewPacketIdentifier();
-                await SendAndReceiveAsync<MqttPubAckPacket>(publishPacket);
+                ClientId = _options.ClientId,
+                Username = _options.UserName,
+                Password = _options.Password,
+                CleanSession = _options.CleanSession,
+                KeepAlivePeriod = (ushort)_options.KeepAlivePeriod.TotalSeconds,
+                WillMessage = willApplicationMessage
+            };
+
+            var response = await SendAndReceiveAsync<MqttConnAckPacket>(connectPacket).ConfigureAwait(false);
+            if (response.ConnectReturnCode != MqttConnectReturnCode.ConnectionAccepted)
+            {
+                throw new MqttConnectingFailedException(response.ConnectReturnCode);
             }
-            else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.ExactlyOnce)
+        }
+
+        private async Task SetupIncomingPacketProcessingAsync()
+        {
+            _isReceivingPackets = false;
+
+#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
+            Task.Factory.StartNew(
+                () => ReceivePackets(_cancellationTokenSource.Token),
+                _cancellationTokenSource.Token,
+                TaskCreationOptions.LongRunning,
+                TaskScheduler.Default).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 && _cancellationTokenSource != null && !_cancellationTokenSource.IsCancellationRequested)
             {
-                publishPacket.PacketIdentifier = GetNewPacketIdentifier();
-                await SendAndReceiveAsync<MqttPubRecPacket>(publishPacket);
-                await SendAsync(publishPacket.CreateResponse<MqttPubCompPacket>());
+                await Task.Delay(TimeSpan.FromMilliseconds(100));
             }
         }
 
@@ -174,76 +215,87 @@ namespace MQTTnet.Core.Client
             if (!IsConnected) throw new MqttCommunicationException("The client is not connected.");
         }
 
+        private void ThrowIfConnected(string message)
+        {
+            if (IsConnected) throw new MqttProtocolViolationException(message);
+        }
+
         private async Task DisconnectInternalAsync()
         {
+            var cts = _cancellationTokenSource;
+            if (cts == null || cts.IsCancellationRequested)
+            {
+                return;
+            }
+
+            cts.Cancel(false);
+            cts.Dispose();
+            _cancellationTokenSource = null;
+
             try
             {
-                await _adapter.DisconnectAsync();
+                await _adapter.DisconnectAsync(_options.DefaultCommunicationTimeout).ConfigureAwait(false);
+                MqttNetTrace.Information(nameof(MqttClient), "Disconnected from adapter.");
             }
-            catch
+            catch (Exception exception)
             {
+                MqttNetTrace.Warning(nameof(MqttClient), exception, "Error while disconnecting from adapter.");
             }
             finally
             {
-                _cancellationTokenSource?.Cancel();
-                IsConnected = false;
                 Disconnected?.Invoke(this, EventArgs.Empty);
             }
         }
 
-        private async void ProcessReceivedPacket(MqttBasePacket mqttPacket)
+        private async Task ProcessReceivedPacketAsync(MqttBasePacket packet)
         {
             try
             {
-                if (mqttPacket is MqttPingReqPacket)
+                MqttNetTrace.Information(nameof(MqttClient), "Received <<< {0}", packet);
+
+                if (packet is MqttPingReqPacket)
                 {
                     await SendAsync(new MqttPingRespPacket());
                     return;
                 }
 
-                if (mqttPacket is MqttDisconnectPacket)
+                if (packet is MqttDisconnectPacket)
                 {
                     await DisconnectAsync();
                     return;
                 }
 
-                var publishPacket = mqttPacket as MqttPublishPacket;
-                if (publishPacket != null)
+                if (packet is MqttPublishPacket publishPacket)
                 {
                     await ProcessReceivedPublishPacket(publishPacket);
                     return;
                 }
 
-                var pubRelPacket = mqttPacket as MqttPubRelPacket;
-                if (pubRelPacket != null)
+                if (packet is MqttPubRelPacket pubRelPacket)
                 {
                     await ProcessReceivedPubRelPacket(pubRelPacket);
                     return;
                 }
 
-                _packetDispatcher.Dispatch(mqttPacket);
+                _packetDispatcher.Dispatch(packet);
             }
             catch (Exception exception)
             {
-                MqttTrace.Error(nameof(MqttClient), exception, "Error while processing received packet.");
+                MqttNetTrace.Error(nameof(MqttClient), exception, "Unhandled exception while processing received packet.");
             }
         }
 
         private void FireApplicationMessageReceivedEvent(MqttPublishPacket publishPacket)
         {
-            if (publishPacket.QualityOfServiceLevel != MqttQualityOfServiceLevel.AtMostOnce)
+            try
             {
-                _processedPublishPackets.Add(publishPacket.PacketIdentifier);
+                var applicationMessage = publishPacket.ToApplicationMessage();
+                ApplicationMessageReceived?.Invoke(this, new MqttApplicationMessageReceivedEventArgs(applicationMessage));
+            }
+            catch (Exception exception)
+            {
+                MqttNetTrace.Error(nameof(MqttClient), exception, "Unhandled exception while handling application message.");
             }
-
-            var applicationMessage = new MqttApplicationMessage(
-                publishPacket.Topic,
-                publishPacket.Payload,
-                publishPacket.QualityOfServiceLevel,
-                publishPacket.Retain
-            );
-
-            ApplicationMessageReceived?.Invoke(this, new MqttApplicationMessageReceivedEventArgs(applicationMessage));
         }
 
         private async Task ProcessReceivedPublishPacket(MqttPublishPacket publishPacket)
@@ -251,66 +303,52 @@ namespace MQTTnet.Core.Client
             if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtMostOnce)
             {
                 FireApplicationMessageReceivedEvent(publishPacket);
+                return;
             }
-            else
+
+            if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtLeastOnce)
             {
-                if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtLeastOnce)
-                {
-                    FireApplicationMessageReceivedEvent(publishPacket);
-                    await SendAsync(new MqttPubAckPacket { PacketIdentifier = publishPacket.PacketIdentifier });
-                }
-                else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.ExactlyOnce)
-                {
-                    _pendingExactlyOncePublishPackets[publishPacket.PacketIdentifier] = publishPacket;
-                    await SendAsync(new MqttPubRecPacket { PacketIdentifier = publishPacket.PacketIdentifier });
-                }
+                FireApplicationMessageReceivedEvent(publishPacket);
+                await 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;
+            }
+
+            throw new MqttCommunicationException("Received a not supported QoS level.");
         }
 
-        private async Task ProcessReceivedPubRelPacket(MqttPubRelPacket pubRelPacket)
+        private Task ProcessReceivedPubRelPacket(MqttPubRelPacket pubRelPacket)
         {
-            MqttPublishPacket originalPublishPacket;
-            if (!_pendingExactlyOncePublishPackets.TryRemove(pubRelPacket.PacketIdentifier, out originalPublishPacket))
+            lock (_unacknowledgedPublishPackets)
             {
-                throw new MqttCommunicationException();
+                _unacknowledgedPublishPackets.Remove(pubRelPacket.PacketIdentifier);
             }
 
-            await SendAsync(originalPublishPacket.CreateResponse<MqttPubCompPacket>());
-
-            FireApplicationMessageReceivedEvent(originalPublishPacket);
+            return SendAsync(pubRelPacket.CreateResponse<MqttPubCompPacket>());
         }
 
-        private async Task SendAsync(MqttBasePacket packet)
+        private Task SendAsync(MqttBasePacket packet)
         {
-            await _adapter.SendPacketAsync(packet, _options.DefaultCommunicationTimeout);
+            return _adapter.SendPacketsAsync(_options.DefaultCommunicationTimeout, _cancellationTokenSource.Token, packet);
         }
 
         private async Task<TResponsePacket> SendAndReceiveAsync<TResponsePacket>(MqttBasePacket requestPacket) where TResponsePacket : MqttBasePacket
         {
-            Func<MqttBasePacket, bool> responsePacketSelector = p =>
-            {
-                var p1 = p as TResponsePacket;
-                if (p1 == null)
-                {
-                    return false;
-                }
-
-                var pi1 = requestPacket as IPacketWithIdentifier;
-                var pi2 = p as IPacketWithIdentifier;
-
-                if (pi1 != null && pi2 != null)
-                {
-                    if (pi1.PacketIdentifier != pi2.PacketIdentifier)
-                    {
-                        return false;
-                    }
-                }
-
-                return true;
-            };
-
-            await _adapter.SendPacketAsync(requestPacket, _options.DefaultCommunicationTimeout);
-            return (TResponsePacket)await _packetDispatcher.WaitForPacketAsync(responsePacketSelector, _options.DefaultCommunicationTimeout);
+            var packetAwaiter = _packetDispatcher.WaitForPacketAsync(requestPacket, typeof(TResponsePacket), _options.DefaultCommunicationTimeout);
+            await _adapter.SendPacketsAsync(_options.DefaultCommunicationTimeout, _cancellationTokenSource.Token, requestPacket).ConfigureAwait(false);
+            return (TResponsePacket)await packetAwaiter.ConfigureAwait(false);
         }
 
         private ushort GetNewPacketIdentifier()
@@ -320,55 +358,100 @@ namespace MQTTnet.Core.Client
 
         private async Task SendKeepAliveMessagesAsync(CancellationToken cancellationToken)
         {
-            MqttTrace.Information(nameof(MqttClient), "Start sending keep alive packets.");
+            MqttNetTrace.Information(nameof(MqttClient), "Start sending keep alive packets.");
 
             try
             {
                 while (!cancellationToken.IsCancellationRequested)
                 {
-                    await Task.Delay(_options.KeepAlivePeriod, cancellationToken);
-                    await SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket());
+                    await Task.Delay(_options.KeepAlivePeriod, cancellationToken).ConfigureAwait(false);
+                    if (cancellationToken.IsCancellationRequested)
+                    {
+                        return;
+                    }
+
+                    await SendAndReceiveAsync<MqttPingRespPacket>(new MqttPingReqPacket()).ConfigureAwait(false);
                 }
             }
-            catch (MqttCommunicationException)
+            catch (OperationCanceledException)
             {
             }
+            catch (MqttCommunicationException exception)
+            {
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    return;
+                }
+
+                MqttNetTrace.Warning(nameof(MqttClient), exception, "MQTT communication exception while sending/receiving keep alive packets.");
+                await DisconnectInternalAsync().ConfigureAwait(false);
+            }
             catch (Exception exception)
             {
-                MqttTrace.Warning(nameof(MqttClient), exception, "Error while sending/receiving keep alive packets.");
+                MqttNetTrace.Warning(nameof(MqttClient), exception, "Unhandled exception while sending/receiving keep alive packets.");
+                await DisconnectInternalAsync().ConfigureAwait(false);
             }
             finally
             {
-                MqttTrace.Information(nameof(MqttClient), "Stopped sending keep alive packets.");
-                await DisconnectInternalAsync();
+                MqttNetTrace.Information(nameof(MqttClient), "Stopped sending keep alive packets.");
             }
         }
 
         private async Task ReceivePackets(CancellationToken cancellationToken)
         {
-            MqttTrace.Information(nameof(MqttClient), "Start receiving packets.");
+            MqttNetTrace.Information(nameof(MqttClient), "Start receiving packets.");
+
             try
             {
                 while (!cancellationToken.IsCancellationRequested)
                 {
-                    var mqttPacket = await _adapter.ReceivePacketAsync(TimeSpan.Zero);
-                    MqttTrace.Information(nameof(MqttClient), $"Received <<< {mqttPacket}");
+                    _isReceivingPackets = true;
 
-                    Task.Run(() => ProcessReceivedPacket(mqttPacket), cancellationToken).Forget();
+                    var packet = await _adapter.ReceivePacketAsync(TimeSpan.Zero, cancellationToken).ConfigureAwait(false);
+                    if (cancellationToken.IsCancellationRequested)
+                    {
+                        return;
+                    }
+
+                    StartProcessReceivedPacket(packet, cancellationToken);
                 }
             }
-            catch (MqttCommunicationException)
+            catch (OperationCanceledException)
             {
             }
+            catch (MqttCommunicationException exception)
+            {
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    return;
+                }
+
+                MqttNetTrace.Warning(nameof(MqttClient), exception, "MQTT communication exception while receiving packets.");
+                await DisconnectInternalAsync().ConfigureAwait(false);
+            }
             catch (Exception exception)
             {
-                MqttTrace.Error(nameof(MqttClient), exception, "Error while receiving packets.");
+                MqttNetTrace.Error(nameof(MqttClient), exception, "Unhandled exception while receiving packets.");
+                await DisconnectInternalAsync().ConfigureAwait(false);
             }
             finally
             {
-                MqttTrace.Information(nameof(MqttClient), "Stopped receiving packets.");
-                await DisconnectInternalAsync();
+                MqttNetTrace.Information(nameof(MqttClient), "Stopped receiving packets.");
             }
         }
+
+        private void StartProcessReceivedPacket(MqttBasePacket packet, CancellationToken cancellationToken)
+        {
+#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), 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 void StartSendKeepAliveMessages(CancellationToken cancellationToken)
+        {
+#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
+            Task.Factory.StartNew(() => SendKeepAliveMessagesAsync(cancellationToken), cancellationToken, TaskCreationOptions.LongRunning, TaskScheduler.Default).ConfigureAwait(false);
+#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
+        }
     }
 }

MQTTnet.Core/Client/MqttClientExtensions.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using MQTTnet.Core.Packets;
+
+namespace MQTTnet.Core.Client
+{
+    public static class MqttClientExtensions
+    {
+        public static Task PublishAsync(this IMqttClient client, params MqttApplicationMessage[] applicationMessages)
+        {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+            if (applicationMessages == null) throw new ArgumentNullException(nameof(applicationMessages));
+
+            return client.PublishAsync(applicationMessages);
+        }
+
+        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 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());
+        }
+    }
+}

MQTTnet.Core/Client/MqttClientOptions.cs

@@ -1,12 +1,13 @@
 using System;
+using MQTTnet.Core.Serializer;
 
 namespace MQTTnet.Core.Client
 {
-    public class MqttClientOptions
+    public abstract class MqttClientOptions
     {
-        public string Server { get; set; }
+        public MqttClientTlsOptions TlsOptions { get; set; } = new MqttClientTlsOptions();
 
-        public int Port { get; set; } = 1883;
+        public MqttApplicationMessage WillMessage { get; set; }
 
         public string UserName { get; set; }
 
@@ -14,8 +15,12 @@ namespace MQTTnet.Core.Client
 
         public string ClientId { get; set; } = Guid.NewGuid().ToString().Replace("-", string.Empty);
 
+        public bool CleanSession { get; set; } = true;
+
         public TimeSpan KeepAlivePeriod { get; set; } = TimeSpan.FromSeconds(5);
 
         public TimeSpan DefaultCommunicationTimeout { get; set; } = TimeSpan.FromSeconds(10);
+
+        public MqttProtocolVersion ProtocolVersion { get; set; } = MqttProtocolVersion.V311;
     }
 }

MQTTnet.Core/Client/MqttClientTcpOptions.cs

@@ -0,0 +1,9 @@
+namespace MQTTnet.Core.Client
+{
+    public class MqttClientTcpOptions : MqttClientOptions
+    {
+        public string Server { get; set; }
+
+        public int? Port { get; set; }
+    }
+}

MQTTnet.Core/Client/MqttClientTcpOptionsExtensions.cs

@@ -0,0 +1,19 @@
+using System;
+
+namespace MQTTnet.Core.Client
+{
+    public static class MqttClientTcpOptionsExtensions
+    {
+        public static int GetPort(this MqttClientTcpOptions options)
+        {
+            if (options == null) throw new ArgumentNullException(nameof(options));
+
+            if (options.Port.HasValue)
+            {
+                return options.Port.Value;
+            }
+
+            return !options.TlsOptions.UseTls ? 1883 : 8883;
+        }
+    }
+}

MQTTnet.Core/Client/MqttClientTlsOptions.cs

@@ -0,0 +1,17 @@
+using System.Collections.Generic;
+
+namespace MQTTnet.Core.Client
+{
+    public sealed class MqttClientTlsOptions
+    {
+        public bool UseTls { get; set; }
+
+        public bool IgnoreCertificateRevocationErrors { get; set; }
+
+        public bool IgnoreCertificateChainErrors { get; set; }
+
+        public bool AllowUntrustedCertificates { get; set; }
+
+        public List<byte[]> Certificates { get; set; }
+    }
+}

MQTTnet.Core/Client/MqttClientWebSocketOptions.cs

@@ -0,0 +1,7 @@
+namespace MQTTnet.Core.Client
+{
+    public class MqttClientWebSocketOptions : MqttClientOptions
+    {
+        public string Uri { get; set; }
+    }
+}

MQTTnet.Core/Client/MqttPacketAwaiter.cs

@@ -1,16 +0,0 @@
-using System;
-using System.Threading.Tasks;
-using MQTTnet.Core.Packets;
-
-namespace MQTTnet.Core.Client
-{
-    public class MqttPacketAwaiter : TaskCompletionSource<MqttBasePacket>
-    {
-        public MqttPacketAwaiter(Func<MqttBasePacket, bool> packetSelector)
-        {
-            PacketSelector = packetSelector ?? throw new ArgumentNullException(nameof(packetSelector));
-        }
-
-        public Func<MqttBasePacket, bool> PacketSelector { get; }
-    }
-}

MQTTnet.Core/Client/MqttPacketDispatcher.cs

@@ -1,111 +1,96 @@
 using System;
-using System.Collections.Generic;
 using System.Threading.Tasks;
 using MQTTnet.Core.Diagnostics;
 using MQTTnet.Core.Exceptions;
+using MQTTnet.Core.Internal;
 using MQTTnet.Core.Packets;
+using System.Collections.Concurrent;
 
 namespace MQTTnet.Core.Client
 {
     public class MqttPacketDispatcher
     {
-        private readonly object _syncRoot = new object();
-        private readonly List<MqttBasePacket> _receivedPackets = new List<MqttBasePacket>();
-        private readonly List<MqttPacketAwaiter> _packetAwaiters = new List<MqttPacketAwaiter>();
+        private readonly ConcurrentDictionary<Type, TaskCompletionSource<MqttBasePacket>> _packetByResponseType = new ConcurrentDictionary<Type, TaskCompletionSource<MqttBasePacket>>();
+        private readonly ConcurrentDictionary<Type, ConcurrentDictionary<ushort, TaskCompletionSource<MqttBasePacket>>> _packetByResponseTypeAndIdentifier = new ConcurrentDictionary<Type, ConcurrentDictionary<ushort, TaskCompletionSource<MqttBasePacket>>>();
 
-        public async Task<MqttBasePacket> WaitForPacketAsync(Func<MqttBasePacket, bool> selector, TimeSpan timeout)
+        public async Task<MqttBasePacket> WaitForPacketAsync(MqttBasePacket request, Type responseType, TimeSpan timeout)
         {
-            if (selector == null) throw new ArgumentNullException(nameof(selector));
+            if (request == null) throw new ArgumentNullException(nameof(request));
 
-            var packetAwaiter = AddPacketAwaiter(selector);
-            DispatchPendingPackets();
-
-            var hasTimeout = await Task.WhenAny(Task.Delay(timeout), packetAwaiter.Task) != packetAwaiter.Task;
-            RemovePacketAwaiter(packetAwaiter);
-
-            if (hasTimeout)
+            var packetAwaiter = AddPacketAwaiter(request, responseType);
+            try
             {
-                MqttTrace.Warning(nameof(MqttPacketDispatcher), "Timeout while waiting for packet.");
-                throw new MqttCommunicationTimedOutException();
+                return await packetAwaiter.Task.TimeoutAfter(timeout).ConfigureAwait(false);
+            }
+            catch (MqttCommunicationTimedOutException)
+            {
+                MqttNetTrace.Warning(nameof(MqttPacketDispatcher), "Timeout while waiting for packet of type '{0}'.", responseType.Name);
+                throw;
+            }
+            finally
+            {
+                RemovePacketAwaiter(request, responseType);
             }
-
-            return packetAwaiter.Task.Result;
         }
 
         public void Dispatch(MqttBasePacket packet)
         {
             if (packet == null) throw new ArgumentNullException(nameof(packet));
 
-            var packetDispatched = false;
-            foreach (var packetAwaiter in GetPacketAwaiters())
+            var type = packet.GetType();
+            if (packet is IMqttPacketWithIdentifier withIdentifier)
             {
-                if (packetAwaiter.PacketSelector(packet))
+                if (_packetByResponseTypeAndIdentifier.TryGetValue(type, out var byid))
                 {
-                    packetAwaiter.SetResult(packet);
-                    packetDispatched = true;
-                    break;
+                    if (byid.TryRemove(withIdentifier.PacketIdentifier, out var tcs))
+                    {
+                        tcs.TrySetResult(packet);
+                        return;
+                    }
                 }
             }
+            else if (_packetByResponseType.TryRemove(type, out var tcs))
+            {
+                tcs.TrySetResult(packet);
+                return;
+            }
 
-            lock (_syncRoot)
-            {
-                if (!packetDispatched)
-                {
-                    _receivedPackets.Add(packet);
-                }
-                else
-                {
-                    _receivedPackets.Remove(packet);
-                }
-            }
+            throw new InvalidOperationException($"Packet of type '{type.Name}' not handled or dispatched.");
         }
 
         public void Reset()
         {
-            lock (_syncRoot)
-            {
-                _packetAwaiters.Clear();
-                _receivedPackets.Clear();
-            }
+            _packetByResponseTypeAndIdentifier.Clear();
+            _packetByResponseType.Clear();
         }
 
-        private List<MqttPacketAwaiter> GetPacketAwaiters()
+        private TaskCompletionSource<MqttBasePacket> AddPacketAwaiter(MqttBasePacket request, Type responseType)
         {
-            lock (_packetAwaiters)
+            var tcs = new TaskCompletionSource<MqttBasePacket>();
+
+            if (request is IMqttPacketWithIdentifier requestWithIdentifier)
             {
-                return new List<MqttPacketAwaiter>(_packetAwaiters);
+                var byId = _packetByResponseTypeAndIdentifier.GetOrAdd(responseType, key => new ConcurrentDictionary<ushort, TaskCompletionSource<MqttBasePacket>>());
+                byId[requestWithIdentifier.PacketIdentifier] = tcs;
             }
+            else
+            {
+                _packetByResponseType[responseType] = tcs;
+            }
+
+            return tcs;
         }
 
-        private MqttPacketAwaiter AddPacketAwaiter(Func<MqttBasePacket, bool> selector)
+        private void RemovePacketAwaiter(MqttBasePacket request, Type responseType)
         {
-            lock (_syncRoot)
+            if (request is IMqttPacketWithIdentifier requestWithIdentifier)
             {
-                var packetAwaiter = new MqttPacketAwaiter(selector);
-                _packetAwaiters.Add(packetAwaiter);
-                return packetAwaiter;
+                var byId = _packetByResponseTypeAndIdentifier.GetOrAdd(responseType, key => new ConcurrentDictionary<ushort, TaskCompletionSource<MqttBasePacket>>());
+                byId.TryRemove(requestWithIdentifier.PacketIdentifier, out var _);
             }
-        }
-
-        private void RemovePacketAwaiter(MqttPacketAwaiter packetAwaiter)
-        {
-            lock (_syncRoot)
+            else
             {
-                _packetAwaiters.Remove(packetAwaiter);
-            }
-        }
-
-        private void DispatchPendingPackets()
-        {
-            List<MqttBasePacket> receivedPackets;
-            lock (_syncRoot)
-            {
-                receivedPackets = new List<MqttBasePacket>(_receivedPackets);
-            }
-
-            foreach (var pendingPacket in receivedPackets)
-            {
-                Dispatch(pendingPacket);
+                _packetByResponseType.TryRemove(responseType, out var _);
             }
         }
     }

MQTTnet.Core/Diagnostics/MqttNetTrace.cs

@@ -0,0 +1,63 @@
+using System;
+
+namespace MQTTnet.Core.Diagnostics
+{
+    public static class MqttNetTrace
+    {
+        public static event EventHandler<MqttNetTraceMessagePublishedEventArgs> TraceMessagePublished;
+
+        public static void Verbose(string source, string message, params object[] parameters)
+        {
+            Publish(source, MqttNetTraceLevel.Verbose, null, message, parameters);
+        }
+
+        public static void Information(string source, string message, params object[] parameters)
+        {
+            Publish(source, MqttNetTraceLevel.Information, null, message, parameters);
+        }
+
+        public static void Warning(string source, string message, params object[] parameters)
+        {
+            Publish(source, MqttNetTraceLevel.Warning, null, message, parameters);
+        }
+
+        public static void Warning(string source, Exception exception, string message, params object[] parameters)
+        {
+            Publish(source, MqttNetTraceLevel.Warning, exception, message, parameters);
+        }
+
+        public static void Error(string source, string message, params object[] parameters)
+        {
+            Publish(source, MqttNetTraceLevel.Error, null, message, parameters);
+        }
+
+        public static void Error(string source, Exception exception, string message, params object[] parameters)
+        {
+            Publish(source, MqttNetTraceLevel.Error, exception, message, parameters);
+        }
+
+        private static void Publish(string source, MqttNetTraceLevel traceLevel, Exception exception, string message, params object[] parameters)
+        {
+            var handler = TraceMessagePublished;
+            if (handler == null)
+            {
+                return;
+            }
+
+            if (parameters?.Length > 0)
+            {
+                try
+                {
+                    message = string.Format(message, parameters);
+                }
+                catch (Exception formatException)
+                {
+                    Error(nameof(MqttNetTrace), formatException, "Error while tracing message: " + message);
+                    return;
+                }
+            }
+
+            handler.Invoke(null, new MqttNetTraceMessagePublishedEventArgs(Environment.CurrentManagedThreadId, source, traceLevel, message, exception));
+        }
+    }
+}

MQTTnet.Core/Diagnostics/MqttNetTraceLevel.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Diagnostics
 {
-    public enum  MqttTraceLevel
+    public enum MqttNetTraceLevel
     {
         Verbose,
         Information,

MQTTnet.Core/Diagnostics/MqttNetTraceMessagePublishedEventArgs.cs

@@ -2,9 +2,9 @@
 
 namespace MQTTnet.Core.Diagnostics
 {
-    public class MqttTraceMessagePublishedEventArgs : EventArgs
+    public sealed class MqttNetTraceMessagePublishedEventArgs : EventArgs
     {
-        public MqttTraceMessagePublishedEventArgs(int threadId, string source, MqttTraceLevel level, string message, Exception exception)
+        public MqttNetTraceMessagePublishedEventArgs(int threadId, string source, MqttNetTraceLevel level, string message, Exception exception)
         {
             ThreadId = threadId;
             Source = source;
@@ -17,7 +17,7 @@ namespace MQTTnet.Core.Diagnostics
 
         public string Source { get; }
 
-        public MqttTraceLevel Level { get; }
+        public MqttNetTraceLevel Level { get; }
 
         public string Message { get; }
 

MQTTnet.Core/Diagnostics/MqttTrace.cs

@@ -1,44 +0,0 @@
-using System;
-
-namespace MQTTnet.Core.Diagnostics
-{
-    public static class MqttTrace
-    {
-        public static event EventHandler<MqttTraceMessagePublishedEventArgs> TraceMessagePublished;
-
-        public static void Verbose(string source, string message)
-        {
-            Publish(source, MqttTraceLevel.Verbose, null, message);
-        }
-
-        public static void Information(string source, string message)
-        {
-            Publish(source, MqttTraceLevel.Information, null, message);
-        }
-
-        public static void Warning(string source, string message)
-        {
-            Publish(source, MqttTraceLevel.Warning, null, message);
-        }
-
-        public static void Warning(string source, Exception exception, string message)
-        {
-            Publish(source, MqttTraceLevel.Warning, exception, message);
-        }
-
-        public static void Error(string source, string message)
-        {
-            Publish(source, MqttTraceLevel.Error, null, message);
-        }
-
-        public static void Error(string source, Exception exception, string message)
-        {
-            Publish(source, MqttTraceLevel.Error, exception, message);
-        }
-
-        private static void Publish(string source, MqttTraceLevel traceLevel, Exception exception, string message)
-        {
-            TraceMessagePublished?.Invoke(null, new MqttTraceMessagePublishedEventArgs(Environment.CurrentManagedThreadId, source, traceLevel, message, exception));
-        }
-    }
-}

MQTTnet.Core/Exceptions/MqttCommunicationException.cs

@@ -4,7 +4,7 @@ namespace MQTTnet.Core.Exceptions
 {
     public class MqttCommunicationException : Exception
     {
-        public MqttCommunicationException()
+        protected MqttCommunicationException()
         {
         }
 
@@ -17,5 +17,10 @@ namespace MQTTnet.Core.Exceptions
             : base(message)
         {
         }
+
+        public MqttCommunicationException(string message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
     }
 }

MQTTnet.Core/Exceptions/MqttCommunicationTimedOutException.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Exceptions
 {
-    public class MqttCommunicationTimedOutException : MqttCommunicationException
+    public sealed class MqttCommunicationTimedOutException : MqttCommunicationException
     {
     }
 }

MQTTnet.Core/Exceptions/MqttProtocolViolationException.cs

@@ -2,9 +2,9 @@
 
 namespace MQTTnet.Core.Exceptions
 {
-    public class MqttProtocolViolationException : Exception
+    public sealed class MqttProtocolViolationException : Exception
     {
-        public MqttProtocolViolationException(string message) 
+        public MqttProtocolViolationException(string message)
             : base(message)
         {
         }

MQTTnet.Core/Internal/MqttApplicationMessageExtensions.cs

@@ -4,6 +4,16 @@ namespace MQTTnet.Core.Internal
 {
     internal static class MqttApplicationMessageExtensions
     {
+        public static MqttApplicationMessage ToApplicationMessage(this MqttPublishPacket publishPacket)
+        {
+            return new MqttApplicationMessage(
+                publishPacket.Topic,
+                publishPacket.Payload,
+                publishPacket.QualityOfServiceLevel,
+                publishPacket.Retain
+            );
+        }
+
         public static MqttPublishPacket ToPublishPacket(this MqttApplicationMessage applicationMessage)
         {
             if (applicationMessage == null)

MQTTnet.Core/Internal/TaskExtensions.cs

@@ -1,11 +1,74 @@
-using System.Threading.Tasks;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Core.Exceptions;
 
 namespace MQTTnet.Core.Internal
 {
-    internal static class TaskExtensions
+    public static class TaskExtensions
     {
-        public static void Forget(this Task task)
+        public static async Task TimeoutAfter(this Task task, TimeSpan timeout)
         {
+            using (var cancellationTokenSource = new CancellationTokenSource())
+            {
+                try
+                {
+                    var timeoutTask = Task.Delay(timeout, cancellationTokenSource.Token);
+                    var finishedTask = await Task.WhenAny(timeoutTask, task).ConfigureAwait(false);
+
+                    if (finishedTask == timeoutTask)
+                    {
+                        throw new MqttCommunicationTimedOutException();
+                    }
+
+                    if (task.IsCanceled)
+                    {
+                        throw new TaskCanceledException();
+                    }
+
+                    if (task.IsFaulted)
+                    {
+                        throw new MqttCommunicationException(task.Exception.GetBaseException());
+                    }
+                }
+                finally
+                {
+                    cancellationTokenSource.Cancel();
+                }
+            }
+        }
+
+        public static async Task<TResult> TimeoutAfter<TResult>(this Task<TResult> task, TimeSpan timeout)
+        {
+            using (var cancellationTokenSource = new CancellationTokenSource())
+            {
+                try
+                {
+                    var timeoutTask = Task.Delay(timeout, cancellationTokenSource.Token);
+                    var finishedTask = await Task.WhenAny(timeoutTask, task).ConfigureAwait(false);
+
+                    if (finishedTask == timeoutTask)
+                    {
+                        throw new MqttCommunicationTimedOutException();
+                    }
+
+                    if (task.IsCanceled)
+                    {
+                        throw new TaskCanceledException();
+                    }
+
+                    if (task.IsFaulted)
+                    {
+                        throw new MqttCommunicationException(task.Exception.GetBaseException());
+                    }
+
+                    return task.Result;
+                }
+                finally
+                {
+                    cancellationTokenSource.Cancel();
+                }
+            }
         }
     }
 }

MQTTnet.Core/MQTTnet.Core.csproj

@@ -1,107 +1,35 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+<Project Sdk="Microsoft.NET.Sdk">
+
   <PropertyGroup>
-    <MinimumVisualStudioVersion>10.0</MinimumVisualStudioVersion>
-    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
-    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-    <ProjectGuid>{99C884F3-B4B9-417D-AA92-DC7DD1C4CFEE}</ProjectGuid>
-    <OutputType>Library</OutputType>
-    <AppDesignerFolder>Properties</AppDesignerFolder>
-    <RootNamespace>MQTTnet.Core</RootNamespace>
+    <TargetFramework>netstandard1.1</TargetFramework>
     <AssemblyName>MQTTnet.Core</AssemblyName>
-    <DefaultLanguage>en-US</DefaultLanguage>
-    <FileAlignment>512</FileAlignment>
-    <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
-    <TargetFrameworkProfile>Profile111</TargetFrameworkProfile>
-    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <RootNamespace>MQTTnet.Core</RootNamespace>
+    <GeneratePackageOnBuild>False</GeneratePackageOnBuild>
+    <DebugType>Full</DebugType>
+    <Description></Description>
+    <Product></Product>
+    <Company></Company>
+    <Authors></Authors>
+    <Version>0.0.0.0</Version>
+    <PackageId></PackageId>
+    <Copyright></Copyright>
+    <PackageProjectUrl></PackageProjectUrl>
+    <PackageIconUrl></PackageIconUrl>
+    <RepositoryUrl></RepositoryUrl>
+    <PackageTags></PackageTags>
+    <FileVersion>2.4.0.0</FileVersion>
+    <AssemblyVersion>2.4.0.0</AssemblyVersion>
+    <PackageLicenseUrl></PackageLicenseUrl>
   </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-    <DebugSymbols>true</DebugSymbols>
-    <DebugType>full</DebugType>
-    <Optimize>false</Optimize>
-    <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-    <DebugType>pdbonly</DebugType>
-    <Optimize>true</Optimize>
-    <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-  </PropertyGroup>
-  <ItemGroup>
-    <!-- A reference to the entire .NET Framework is automatically included -->
-  </ItemGroup>
-  <ItemGroup>
-    <Compile Include="Adapter\IMqttCommunicationAdapter.cs" />
-    <Compile Include="Adapter\IMqttServerAdapter.cs" />
-    <Compile Include="Adapter\MqttClientConnectedEventArgs.cs" />
-    <Compile Include="Adapter\MqttConnectingFailedException.cs" />
-    <Compile Include="Adapter\MqttChannelCommunicationAdapter.cs" />
-    <Compile Include="Channel\IMqttCommunicationChannel.cs" />
-    <Compile Include="Client\MqttPacketDispatcher.cs" />
-    <Compile Include="Client\MqttSubscribeResult.cs" />
-    <Compile Include="Client\MqttPacketAwaiter.cs" />
-    <Compile Include="Diagnostics\MqttTrace.cs" />
-    <Compile Include="Diagnostics\MqttTraceLevel.cs" />
-    <Compile Include="Diagnostics\MqttTraceMessagePublishedEventArgs.cs" />
-    <Compile Include="Exceptions\MqttCommunicationException.cs" />
-    <Compile Include="Exceptions\MqttCommunicationTimedOutException.cs" />
-    <Compile Include="Exceptions\MqttProtocolViolationException.cs" />
-    <Compile Include="Internal\MqttApplicationMessageExtensions.cs" />
-    <Compile Include="MqttApplicationMessageReceivedEventArgs.cs" />
-    <Compile Include="Packets\IPacketWithPacketIdentifier.cs" />
-    <Compile Include="Packets\MqttConnAckPacket.cs" />
-    <Compile Include="Packets\MqttBasePacket.cs" />
-    <Compile Include="Packets\MqttConnectPacket.cs" />
-    <Compile Include="Packets\MqttDisconnectPacket.cs" />
-    <Compile Include="MqttApplicationMessage.cs" />
-    <Compile Include="Client\MqttClient.cs" />
-    <Compile Include="Client\MqttClientOptions.cs" />
-    <Compile Include="Packets\MqttPingReqPacket.cs" />
-    <Compile Include="Packets\MqttPubCompPacket.cs" />
-    <Compile Include="Packets\MqttBasePublishPacket.cs" />
-    <Compile Include="Packets\MqttUnsubAckPacket.cs" />
-    <Compile Include="Packets\MqttSubAckPacket.cs" />
-    <Compile Include="Packets\MqttPubRelPacket.cs" />
-    <Compile Include="Packets\MqttPingRespPacket.cs" />
-    <Compile Include="Packets\MqttPubAckPacket.cs" />
-    <Compile Include="Packets\MqttPublishPacket.cs" />
-    <Compile Include="Packets\MqttPubRecPacket.cs" />
-    <Compile Include="Packets\MqttUnsubscribe.cs" />
-    <Compile Include="Packets\MqttSubscribePacket.cs" />
-    <Compile Include="Packets\TopicFilter.cs" />
-    <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="Protocol\MqttConnectReturnCode.cs" />
-    <Compile Include="Protocol\MqttControlPacketType.cs" />
-    <Compile Include="Protocol\MqttQualityOfServiceLevel.cs" />
-    <Compile Include="Protocol\MqttSubscribeReturnCode.cs" />
-    <Compile Include="Serializer\ByteReader.cs" />
-    <Compile Include="Serializer\ByteWriter.cs" />
-    <Compile Include="Serializer\DefaultMqttV311PacketSerializer.cs" />
-    <Compile Include="Serializer\IMqttPacketSerializer.cs" />
-    <Compile Include="Serializer\MqttPacketReader.cs" />
-    <Compile Include="Serializer\MqttPacketWriter.cs" />
-    <Compile Include="Server\MqttClientSession.cs" />
-    <Compile Include="Server\MqttClientSessionManager.cs" />
-    <Compile Include="Server\MqttOutgoingPublicationsManager.cs" />
-    <Compile Include="Server\MqttServer.cs" />
-    <Compile Include="Server\MqttServerOptions.cs" />
-    <Compile Include="Server\MqttClientPublishPacketContext.cs" />
-    <Compile Include="Server\MqttTopicFilterComparer.cs" />
-    <Compile Include="Server\MqttClientSubscriptionsManager.cs" />
-    <Compile Include="Internal\TaskExtensions.cs" />
-  </ItemGroup>
-  <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
-  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
-       Other similar extension points exist, see Microsoft.Common.targets.
-  <Target Name="BeforeBuild">
-  </Target>
-  <Target Name="AfterBuild">
-  </Target>
-  -->
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Any CPU|AnyCPU'" />
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Any CPU|x64'" />
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x86'" />
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x86'" />
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Any CPU|x86'" />
+
 </Project>

MQTTnet.Core/MqttApplicationMessage.cs

@@ -3,7 +3,7 @@ using MQTTnet.Core.Protocol;
 
 namespace MQTTnet.Core
 {
-    public class MqttApplicationMessage
+    public sealed class MqttApplicationMessage
     {
         public MqttApplicationMessage(string topic, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, bool retain)
         {

MQTTnet.Core/MqttApplicationMessageFactory.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Globalization;
+using System.IO;
+using System.Text;
+using MQTTnet.Core.Protocol;
+
+namespace MQTTnet.Core
+{
+    public class MqttApplicationMessageFactory
+    {
+        public MqttApplicationMessage CreateApplicationMessage(string topic, MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce, bool retain = false)
+        {
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
+            return CreateApplicationMessage(topic, new byte[0], qualityOfServiceLevel, retain);
+        }
+
+        public MqttApplicationMessage CreateApplicationMessage(string topic, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce, bool retain = false)
+        {
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
+            if (payload == null)
+            {
+                payload = new byte[0];
+            }
+
+            return new MqttApplicationMessage(topic, payload, qualityOfServiceLevel, retain);
+        }
+
+        public MqttApplicationMessage CreateApplicationMessage<TPayload>(string topic, TPayload payload, MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce, bool retain = false)
+        {
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
+            var payloadString = Convert.ToString(payload, CultureInfo.InvariantCulture);
+            var payloadBuffer = string.IsNullOrEmpty(payloadString) ? new byte[0] : Encoding.UTF8.GetBytes(payloadString);
+
+            return CreateApplicationMessage(topic, payloadBuffer, qualityOfServiceLevel, retain);
+        }
+
+        public MqttApplicationMessage CreateApplicationMessage(string topic, Stream payload, MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce, bool retain = false)
+        {
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
+            byte[] payloadBuffer;
+            if (payload == null || payload.Length == 0)
+            {
+                payloadBuffer = new byte[0];
+            }
+            else
+            {
+                payloadBuffer = new byte[payload.Length - payload.Position];
+                payload.Read(payloadBuffer, 0, payloadBuffer.Length);
+            }
+
+            return CreateApplicationMessage(topic, payloadBuffer, qualityOfServiceLevel, retain);
+        }
+    }
+}

MQTTnet.Core/Packets/IMqttPacketWithIdentifier.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Packets
 {
-    public interface IPacketWithIdentifier
+    public interface IMqttPacketWithIdentifier
     {
         ushort PacketIdentifier { get; set; }
     }

MQTTnet.Core/Packets/MqttBasePacket.cs

@@ -1,25 +1,6 @@
-using System;
-
-namespace MQTTnet.Core.Packets
+namespace MQTTnet.Core.Packets
 {
     public abstract class MqttBasePacket
     {
-        public TResponsePacket CreateResponse<TResponsePacket>()
-        {
-            var responsePacket = Activator.CreateInstance<TResponsePacket>();
-            var responsePacketWithIdentifier = responsePacket as IPacketWithIdentifier;
-            if (responsePacketWithIdentifier != null)
-            {
-                var requestPacketWithIdentifier = this as IPacketWithIdentifier;
-                if (requestPacketWithIdentifier == null)
-                {
-                    throw new InvalidOperationException("Response packet has PacketIdentifier but request packet does not.");
-                }
-
-                responsePacketWithIdentifier.PacketIdentifier = requestPacketWithIdentifier.PacketIdentifier;
-            }
-
-            return responsePacket;
-        }
     }
 }

MQTTnet.Core/Packets/MqttBasePublishPacket.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Packets
 {
-    public class MqttBasePublishPacket : MqttBasePacket, IPacketWithIdentifier
+    public class MqttBasePublishPacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
         public ushort PacketIdentifier { get; set; }
     }

MQTTnet.Core/Packets/MqttConnAckPacket.cs

@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Core.Packets
 {
-    public class MqttConnAckPacket : MqttBasePacket
+    public sealed class MqttConnAckPacket : MqttBasePacket
     {
         public bool IsSessionPresent { get; set; }
 
@@ -10,7 +10,7 @@ namespace MQTTnet.Core.Packets
 
         public override string ToString()
         {
-            return $"{nameof(MqttConnAckPacket)}: [ConnectReturnCode={ConnectReturnCode}] [IsSessionPresent={IsSessionPresent}]";
+            return nameof(MqttConnAckPacket) + ": [ConnectReturnCode=" + ConnectReturnCode + "] [IsSessionPresent=" + IsSessionPresent + "]";
         }
     }
 }

MQTTnet.Core/Packets/MqttConnectPacket.cs

@@ -1,7 +1,11 @@
-namespace MQTTnet.Core.Packets
+using MQTTnet.Core.Serializer;
+
+namespace MQTTnet.Core.Packets
 {
-    public class MqttConnectPacket: MqttBasePacket
+    public sealed class MqttConnectPacket : MqttBasePacket
     {
+        public MqttProtocolVersion ProtocolVersion { get; set; }
+
         public string ClientId { get; set; }
 
         public string Username { get; set; }
@@ -16,7 +20,7 @@
 
         public override string ToString()
         {
-            return $"{nameof(MqttConnectPacket)} [ClientId={ClientId}] [Username={Username}] [Password={Password}] [KeepAlivePeriod={KeepAlivePeriod}] [CleanSession={CleanSession}]";
+            return nameof(MqttConnectPacket) + ": [ClientId=" + ClientId + "] [Username=" + Username + "] [Password=" + Password + "] [KeepAlivePeriod=" + KeepAlivePeriod + "] [CleanSession=" + CleanSession + "]";
         }
     }
 }

MQTTnet.Core/Packets/MqttDisconnectPacket.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Packets
 {
-    public class MqttDisconnectPacket : MqttBasePacket
+    public sealed class MqttDisconnectPacket : MqttBasePacket
     {
     }
 }

MQTTnet.Core/Packets/MqttPacketExtensions.cs

@@ -0,0 +1,27 @@
+using System;
+
+namespace MQTTnet.Core.Packets
+{
+    public static class MqttPacketExtensions
+    {
+        public static TResponsePacket CreateResponse<TResponsePacket>(this MqttBasePacket packet)
+        {
+            if (packet == null) throw new ArgumentNullException(nameof(packet));
+
+            var responsePacket = Activator.CreateInstance<TResponsePacket>();
+
+            if (responsePacket is IMqttPacketWithIdentifier responsePacketWithIdentifier)
+            {
+                var requestPacketWithIdentifier = packet as IMqttPacketWithIdentifier;
+                if (requestPacketWithIdentifier == null)
+                {
+                    throw new InvalidOperationException("Response packet has PacketIdentifier but request packet does not.");
+                }
+
+                responsePacketWithIdentifier.PacketIdentifier = requestPacketWithIdentifier.PacketIdentifier;
+            }
+
+            return responsePacket;
+        }
+    }
+}

MQTTnet.Core/Packets/MqttPacketHeader.cs

@@ -0,0 +1,13 @@
+using MQTTnet.Core.Protocol;
+
+namespace MQTTnet.Core.Packets
+{
+    public class MqttPacketHeader
+    {
+        public MqttControlPacketType ControlPacketType { get; set; }
+
+        public byte FixedHeader { get; set; }
+
+        public int BodyLength { get; set; }
+    }
+}

MQTTnet.Core/Packets/MqttPingReqPacket.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Packets
 {
-    public class MqttPingReqPacket : MqttBasePacket
+    public sealed class MqttPingReqPacket : MqttBasePacket
     {
         public override string ToString()
         {

MQTTnet.Core/Packets/MqttPingRespPacket.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Packets
 {
-    public class MqttPingRespPacket : MqttBasePacket
+    public sealed class MqttPingRespPacket : MqttBasePacket
     {
         public override string ToString()
         {

MQTTnet.Core/Packets/MqttPubAckPacket.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Packets
 {
-    public class MqttPubAckPacket : MqttBasePublishPacket
+    public sealed class MqttPubAckPacket : MqttBasePublishPacket
     {
     }
 }

MQTTnet.Core/Packets/MqttPubCompPacket.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Packets
 {
-    public class MqttPubCompPacket : MqttBasePublishPacket
+    public sealed class MqttPubCompPacket : MqttBasePublishPacket
     {
     }
 }

MQTTnet.Core/Packets/MqttPubRecPacket.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Packets
 {
-    public class MqttPubRecPacket : MqttBasePublishPacket
+    public sealed class MqttPubRecPacket : MqttBasePublishPacket
     {
     }
 }

MQTTnet.Core/Packets/MqttPubRelPacket.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Packets
 {
-    public class MqttPubRelPacket : MqttBasePublishPacket
+    public sealed class MqttPubRelPacket : MqttBasePublishPacket
     {
     }
 }

MQTTnet.Core/Packets/MqttPublishPacket.cs

@@ -1,9 +1,9 @@
-using System.Text;
+using System;
 using MQTTnet.Core.Protocol;
 
 namespace MQTTnet.Core.Packets
 {
-    public class MqttPublishPacket : MqttBasePublishPacket
+    public sealed class MqttPublishPacket : MqttBasePublishPacket
     {
         public bool Retain { get; set; }
 
@@ -17,8 +17,13 @@ namespace MQTTnet.Core.Packets
 
         public override string ToString()
         {
-            return
-                $"{nameof(MqttPublishPacket)} [Topic={Topic}] [Payload={Encoding.UTF8.GetString(Payload, 0, Payload.Length)}] [QoSLevel={QualityOfServiceLevel}] [Dup={Dup}] [Retain={Retain}] [PacketIdentifier={PacketIdentifier}]";
+            return nameof(MqttPublishPacket) +
+                ": [Topic=" + Topic + "]" +
+                " [Payload=" + Convert.ToBase64String(Payload) + "]" +
+                " [QoSLevel=" + QualityOfServiceLevel + "]" +
+                " [Dup=" + Dup + "]" +
+                " [Retain=" + Retain + "]" +
+                " [PacketIdentifier=" + PacketIdentifier + "]";
         }
     }
 }

MQTTnet.Core/Packets/MqttSubAckPacket.cs

@@ -4,7 +4,7 @@ using MQTTnet.Core.Protocol;
 
 namespace MQTTnet.Core.Packets
 {
-    public class MqttSubAckPacket : MqttBasePacket, IPacketWithIdentifier
+    public sealed class MqttSubAckPacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
         public ushort PacketIdentifier { get; set; }
 
@@ -13,8 +13,7 @@ namespace MQTTnet.Core.Packets
         public override string ToString()
         {
             var subscribeReturnCodesText = string.Join(",", SubscribeReturnCodes.Select(f => f.ToString()));
-            return
-                $"{nameof(MqttSubAckPacket)} [PacketIdentifier={PacketIdentifier}] [SubscribeReturnCodes={subscribeReturnCodesText}]";
+            return nameof(MqttSubAckPacket) + ": [PacketIdentifier=" + PacketIdentifier + "] [SubscribeReturnCodes=" + subscribeReturnCodesText + "]";
         }
     }
 }

MQTTnet.Core/Packets/MqttSubscribePacket.cs

@@ -3,17 +3,16 @@ using System.Linq;
 
 namespace MQTTnet.Core.Packets
 {
-    public class MqttSubscribePacket : MqttBasePacket, IPacketWithIdentifier
+    public sealed class MqttSubscribePacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
         public ushort PacketIdentifier { get; set; }
-        
+
         public IList<TopicFilter> TopicFilters { get; set; } = new List<TopicFilter>();
 
         public override string ToString()
         {
-            var topicFiltersText = string.Join(",", TopicFilters.Select(f => $"{f.Topic}@{f.QualityOfServiceLevel}"));
-            return
-                $"{nameof(MqttSubscribePacket)} [PacketIdentifier={PacketIdentifier}] [TopicFilters={topicFiltersText}]";
+            var topicFiltersText = string.Join(",", TopicFilters.Select(f => f.Topic + "@" + f.QualityOfServiceLevel));
+            return nameof(MqttSubscribePacket) + ": [PacketIdentifier=" + PacketIdentifier + "] [TopicFilters=" + topicFiltersText + "]";
         }
     }
 }

MQTTnet.Core/Packets/MqttUnsubAckPacket.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Core.Packets
 {
-    public class MqttUnsubAckPacket : MqttBasePacket, IPacketWithIdentifier
+    public sealed class MqttUnsubAckPacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
         public ushort PacketIdentifier { get; set; }
     }

MQTTnet.Core/Packets/MqttUnsubscribe.cs

@@ -2,10 +2,10 @@
 
 namespace MQTTnet.Core.Packets
 {
-    public class MqttUnsubscribePacket : MqttBasePacket, IPacketWithIdentifier
+    public sealed class MqttUnsubscribePacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
         public ushort PacketIdentifier { get; set; }
-        
+
         public IList<string> TopicFilters { get; set; } = new List<string>();
     }
 }

MQTTnet.Core/Packets/TopicFilter.cs

@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Core.Packets
 {
-    public class TopicFilter
+    public sealed class TopicFilter
     {
         public TopicFilter(string topic, MqttQualityOfServiceLevel qualityOfServiceLevel)
         {

MQTTnet.Core/Properties/AssemblyInfo.cs

@@ -1,15 +0,0 @@
-using System.Reflection;
-using System.Runtime.InteropServices;
-
-[assembly: AssemblyTitle("MQTTnet")]
-[assembly: AssemblyDescription("The core library of MQTTnet")]
-[assembly: AssemblyConfiguration("")]
-[assembly: AssemblyCompany("Christian Kratky")]
-[assembly: AssemblyProduct("MQTTnet")]
-[assembly: AssemblyCopyright("Copyright © Christian Kratky 2016-2017")]
-[assembly: AssemblyTrademark("")]
-[assembly: AssemblyCulture("")]
-[assembly: ComVisible(false)]
-[assembly: Guid("0e10d0ea-8e4b-4903-ab9e-93a187d07922")]
-[assembly: AssemblyVersion("2.1.0.4")]
-[assembly: AssemblyFileVersion("2.1.0.4")]

MQTTnet.Core/Serializer/ByteReader.cs

@@ -2,41 +2,47 @@
 
 namespace MQTTnet.Core.Serializer
 {
-    public class ByteReader
+    public sealed class ByteReader
     {
+        private readonly int _source;
         private int _index;
-        private readonly int _byte;
 
-        public ByteReader(byte @byte)
+        public ByteReader(int source)
         {
-            _byte = @byte;
+            _source = source;
         }
 
         public bool Read()
         {
             if (_index >= 8)
             {
-                throw new InvalidOperationException("End of the byte reached.");
+                throw new InvalidOperationException("End of byte reached.");
             }
 
-            var result = ((1 << _index) & _byte) > 0;
+            var result = ((1 << _index) & _source) > 0;
             _index++;
-
             return result;
         }
 
-        public byte Read(int count)
+        public int Read(int count)
         {
+            if (_index + count > 8)
+            {
+                throw new InvalidOperationException("End of byte will be reached.");
+            }
+
             var result = 0;
             for (var i = 0; i < count; i++)
             {
-                if (Read())
+                if (((1 << _index) & _source) > 0)
                 {
                     result |= 1 << i;
                 }
+
+                _index++;
             }
 
-            return (byte)result;
+            return result;
         }
     }
 }

MQTTnet.Core/Serializer/ByteWriter.cs

@@ -2,14 +2,14 @@
 
 namespace MQTTnet.Core.Serializer
 {
-    public class ByteWriter
+    public sealed class ByteWriter
     {
         private int _index;
         private int _byte;
 
         public byte Value => (byte)_byte;
 
-        public void Write(byte @byte, int count)
+        public void Write(int @byte, int count)
         {
             for (var i = 0; i < count; i++)
             {