1681 misleading signature of mqttclientconnectasync mqttclientconnectresultcode expected but throws exception (#1749 )

1724 nullreferenceexception on mqttclientconnectasync (#1748 )
Update MqttClient.cs
2026-10-15 00:15:15 +08:00 · 2023-05-29 16:29:16 +02:00 · 2023-05-29 13:55:36 +02:00 · 2023-05-29 13:53:42 +02:00 · 2023-05-29 13:47:09 +02:00 · 2023-05-29 13:45:44 +02:00
128 changed files with 2471 additions and 2729 deletions
@@ -1,8 +1,13 @@
-* [Core] Added net7.0 builds (#1635, thanks to @YAJeff).
-* [Client] Added support for passing MQTT v5 options (User properties etc.) for disconnects.
-* [Client] An internal exception is no longer caught silently when calling _DisconnectAsync_ to indicate that the disconnect is not clean (BREAKING CHANGE).
-* [Client] MQTTv5 features are now checked and an exception is thrown if they are used when using protocol version 3.1.1 and lower. These checks can be disabled in client options. (BREAKING CHANGE!).
-* [Server] Exposed MQTT v5 sent properties from the affected client in _ClientDisconnectedAsync_ event.
-* [Server] Fixed wrong client ID passed to _InterceptingUnsubscriptionEventArgs_ (#1631, thanks to @ghord). 
-* [Server] Exposed socket settings for TCP keep alive in TCP options (#1544).
-* [Server] Exposed server session items at server level and allow custom session items for injected application messages (#1638).
+* [Core] Add validation of maximum string lengths (#1718).
+* [Core] Added .NET 4.8 builds (#1729).
+* [Core] Exposed more details of DISCONNECT packet in log (#1729).
+* [Core] Fixed _ArgumentNullException_ in _ConvertPayloadToString_ (#1745, thanks to @ramonsmits).
+* [Client] Added overloads for setting packet payload and will payload (#1720).
+* [Client] The proper connect result is now exposed in the _Disconnected_ event when authentication fails (#1139).
+* [Client] Exposed _UseDefaultCredentials_ and more for Web Socket options and proxy options (#1734, thanks to @impworks).
+* [Client] Exposed more TLS options (#1729).
+* [Client] Fixed wrong return code conversion (#1729).
+* [Client] Added an option to avoid throwing an exception when the server returned a proper non success (but valid) response (#1681).
+* [Server] Improved performance by changing internal locking strategy for subscriptions (#1716, thanks to @zeheng).
+* [Server] Fixed exceptions when clients are connecting and disconnecting very fast while accessing the client status for connection validation (#1742).
+* [Server] Exposed more properties in _ClientConnectedEventArgs_ (#1738).
@@ -3,7 +3,7 @@ name: CI
 on: [push, pull_request]

 env:
-  VERSION: "4.2.0.${{github.run_number}}"
+  VERSION: "4.2.1.${{github.run_number}}"

 jobs:
  build:
@@ -1,67 +1,4 @@
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-  &amp;lt;Language id="EditorConfig"&amp;gt;&#xD;
-    &amp;lt;Reformat&amp;gt;true&amp;lt;/Reformat&amp;gt;&#xD;
-  &amp;lt;/Language&amp;gt;&#xD;
-  &amp;lt;Language id="HTML"&amp;gt;&#xD;
-    &amp;lt;Reformat&amp;gt;true&amp;lt;/Reformat&amp;gt;&#xD;
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-    &amp;lt;OptimizeImports&amp;gt;true&amp;lt;/OptimizeImports&amp;gt;&#xD;
-  &amp;lt;/Language&amp;gt;&#xD;
-  &amp;lt;Language id="HTTP Request"&amp;gt;&#xD;
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-    &amp;lt;Reformat&amp;gt;true&amp;lt;/Reformat&amp;gt;&#xD;
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-  &amp;lt;Language id="JSON"&amp;gt;&#xD;
-    &amp;lt;Reformat&amp;gt;true&amp;lt;/Reformat&amp;gt;&#xD;
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-  &amp;lt;Language id="Jade"&amp;gt;&#xD;
-    &amp;lt;Reformat&amp;gt;true&amp;lt;/Reformat&amp;gt;&#xD;
-  &amp;lt;/Language&amp;gt;&#xD;
-  &amp;lt;Language id="JavaScript"&amp;gt;&#xD;
-    &amp;lt;Reformat&amp;gt;true&amp;lt;/Reformat&amp;gt;&#xD;
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-    &amp;lt;OptimizeImports&amp;gt;true&amp;lt;/OptimizeImports&amp;gt;&#xD;
-  &amp;lt;/Language&amp;gt;&#xD;
-  &amp;lt;Language id="Markdown"&amp;gt;&#xD;
-    &amp;lt;Reformat&amp;gt;true&amp;lt;/Reformat&amp;gt;&#xD;
-  &amp;lt;/Language&amp;gt;&#xD;
-  &amp;lt;Language id="Properties"&amp;gt;&#xD;
-    &amp;lt;Reformat&amp;gt;true&amp;lt;/Reformat&amp;gt;&#xD;
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 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpCodeStyle/BRACES_FOR_FOR/@EntryValue">Required</s:String>
 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpCodeStyle/BRACES_FOR_FOREACH/@EntryValue">Required</s:String>
 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpCodeStyle/BRACES_FOR_IFELSE/@EntryValue">Required</s:String>
@@ -71,28 +8,23 @@
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/KEEP_EXISTING_INITIALIZER_ARRANGEMENT/@EntryValue">False</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/KEEP_EXISTING_INVOCATION_PARENS_ARRANGEMENT/@EntryValue">False</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/KEEP_EXISTING_PROPERTY_PATTERNS_ARRANGEMENT/@EntryValue">False</s:Boolean>
-	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/KEEP_EXISTING_SWITCH_EXPRESSION_ARRANGEMENT/@EntryValue">False</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/KEEP_USER_LINEBREAKS/@EntryValue">False</s:Boolean>
 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/PLACE_ACCESSORHOLDER_ATTRIBUTE_ON_SAME_LINE_EX/@EntryValue">NEVER</s:String>
-	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/PLACE_SIMPLE_ACCESSOR_ON_SINGLE_LINE/@EntryValue">False</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/PLACE_SIMPLE_ANONYMOUSMETHOD_ON_SINGLE_LINE/@EntryValue">False</s:Boolean>
 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/PLACE_SIMPLE_EMBEDDED_STATEMENT_ON_SAME_LINE/@EntryValue">NEVER</s:String>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/PLACE_SIMPLE_INITIALIZER_ON_SINGLE_LINE/@EntryValue">False</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/PLACE_SIMPLE_PROPERTY_PATTERN_ON_SINGLE_LINE/@EntryValue">False</s:Boolean>
-	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/PLACE_WHILE_ON_NEW_LINE/@EntryValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/SPACE_WITHIN_METHOD_CALL_PARENTHESES/@EntryValue">False</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/SPACE_WITHIN_METHOD_PARENTHESES/@EntryValue">False</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/SPACE_WITHIN_PARENTHESES/@EntryValue">False</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_AFTER_DECLARATION_LPAR/@EntryValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_AFTER_INVOCATION_LPAR/@EntryValue">True</s:Boolean>
 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_ARGUMENTS_STYLE/@EntryValue">CHOP_IF_LONG</s:String>
-	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_ARRAY_INITIALIZER_STYLE/@EntryValue">CHOP_ALWAYS</s:String>
+	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_ARRAY_INITIALIZER_STYLE/@EntryValue">CHOP_IF_LONG</s:String>
 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_CHAINED_METHOD_CALLS/@EntryValue">CHOP_IF_LONG</s:String>
 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_EXTENDS_LIST_STYLE/@EntryValue">CHOP_IF_LONG</s:String>
 	<s:Int64 x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_LIMIT/@EntryValue">180</s:Int64>
-	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_OBJECT_AND_COLLECTION_INITIALIZER_STYLE/@EntryValue">CHOP_ALWAYS</s:String>
 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_PARAMETERS_STYLE/@EntryValue">CHOP_IF_LONG</s:String>
-	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpFormat/WRAP_PROPERTY_PATTERN/@EntryValue">CHOP_ALWAYS</s:String>
 	<s:Boolean x:Key="/Default/CodeStyle/CodeFormatting/XmlDocFormatter/KeepUserLineBreaks/@EntryValue">True</s:Boolean>
 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/XmlDocFormatter/ProcessingInstructionAttributesFormat/@EntryValue">OnDifferentLines</s:String>
 	<s:String x:Key="/Default/CodeStyle/CodeFormatting/XmlDocFormatter/TagAttributesFormat/@EntryValue">OnDifferentLines</s:String>
@@ -50,6 +50,22 @@ MQTTnet is a high performance .NET library for MQTT based communication. It prov
 * A custom message interceptor can be added which allows transforming or extending every received application message
 * Validate subscriptions and deny subscribing of certain topics depending on requesting clients

+## Getting Started
+
+MQTTnet is delivered via <b>NuGet</b> package manager. You can find the packages here: https://www.nuget.org/packages/MQTTnet/
+
+Use these command in the Package Manager console to install MQTTnet manually:
+```
+Install-Package MQTTnet
+```
+
+Samples for using MQTTnet are part of this repository. For starters these samples are recommended:
+
+- [Connect with a broker](https://github.com/dotnet/MQTTnet/blob/master/Samples/Client/Client_Connection_Samples.cs)
+- [Subscribing to data](https://github.com/dotnet/MQTTnet/blob/master/Samples/Client/Client_Subscribe_Samples.cs)
+- [Publishing data](https://github.com/dotnet/MQTTnet/blob/master/Samples/Client/Client_Publish_Samples.cs)
+- [Host own broker](https://github.com/dotnet/MQTTnet/blob/master/Samples/Server/Server_Simple_Samples.cs)
+
 ## Code of Conduct

 This project has adopted the code of conduct defined by the Contributor Covenant to clarify expected behavior in our community.
@@ -70,6 +70,32 @@ public static class Client_Connection_Samples
            await mqttClient.DisconnectAsync(mqttClientDisconnectOptions, CancellationToken.None);
        }
    }
+    
+    public static async Task Connect_With_Amazon_AWS()
+    {
+        /*
+         * This sample creates a simple MQTT client and connects to an Amazon Web Services broker.
+         *
+         * The broker requires special settings which are set here.
+         */
+
+        var mqttFactory = new MqttFactory();
+
+        using (var mqttClient = mqttFactory.CreateMqttClient())
+        {
+            var mqttClientOptions = new MqttClientOptionsBuilder()
+                .WithTcpServer("amazon.web.services.broker")
+                // Disabling packet fragmentation is very important!  
+                .WithoutPacketFragmentation()
+                .Build();
+            
+            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
+
+            Console.WriteLine("The MQTT client is connected.");
+
+            await mqttClient.DisconnectAsync();
+        }
+    }

    public static async Task Connect_Client_Timeout()
    {
@@ -26,7 +26,7 @@ public static class PackageInspection_Samples
                .WithTcpServer("broker.hivemq.com")
                .Build();
            
-            mqttClient.InspectPackage += OnInspectPackage;
+            mqttClient.InspectPacketAsync += OnInspectPacket;
            
            await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);
            
@@ -39,7 +39,7 @@ public static class PackageInspection_Samples
        }
    }

-    static Task OnInspectPackage(InspectMqttPacketEventArgs eventArgs)
+    static Task OnInspectPacket(InspectMqttPacketEventArgs eventArgs)
    {
        if (eventArgs.Direction == MqttPacketFlowDirection.Inbound)
        {
@@ -44,9 +44,9 @@ public sealed class Managed_Client_Simple_Samples
            Console.WriteLine("The managed MQTT client is connected.");
            
            // Wait until the queue is fully processed.
-            SpinWait.SpinUntil(() => managedMqttClient.EnqueuedApplicationMessagesCount == 0, 10000);
+            SpinWait.SpinUntil(() => managedMqttClient.PendingApplicationMessagesCount == 0, 10000);
            
-            Console.WriteLine($"Pending messages = {managedMqttClient.EnqueuedApplicationMessagesCount}");
+            Console.WriteLine($"Pending messages = {managedMqttClient.PendingApplicationMessagesCount}");
        }
    }
 }
@@ -4,7 +4,13 @@

 using System.Reflection;

-Console.WriteLine("Welcome to MQTTnet samples!");
+Console.BackgroundColor = ConsoleColor.White;
+Console.BackgroundColor = ConsoleColor.Red;
+Console.Title = "Samples - MQTTnet";
+Console.WriteLine("----------------------------------------------");
+Console.WriteLine("-         Welcome to MQTTnet samples!        -");
+Console.WriteLine("----------------------------------------------");
+Console.ResetColor();
 Console.WriteLine();

 var sampleClasses = Assembly.GetExecutingAssembly().GetExportedTypes().OrderBy(c => c.Name).ToList();
@@ -16,7 +22,11 @@ foreach (var sampleClass in sampleClasses)
    index++;
 }

+Console.WriteLine();
+Console.ForegroundColor = ConsoleColor.Green;
 Console.Write("Please choose sample class (press Enter to continue): ");
+Console.ResetColor();
+
 var input = Console.ReadLine();
 var selectedIndex = int.Parse(input ?? "0");
 var selectedSampleClass = sampleClasses[selectedIndex];
@@ -29,12 +39,19 @@ foreach (var sampleMethod in sampleMethods)
    index++;
 }

+Console.WriteLine();
+Console.ForegroundColor = ConsoleColor.Green;
 Console.Write("Please choose sample (press Enter to continue): ");
+Console.ResetColor();
+
 input = Console.ReadLine();
 selectedIndex = int.Parse(input ?? "0");
 var selectedSampleMethod = sampleMethods[selectedIndex];

+Console.WriteLine();
+Console.ForegroundColor = ConsoleColor.White;
 Console.WriteLine("Executing sample...");
+Console.ResetColor();
 Console.WriteLine();

 try
@@ -17,7 +17,7 @@ using MQTTnet.Server;

 namespace MQTTnet.Samples.Server;

-public static class Server_Asp_Net_Samples
+public static class Server_ASP_NET_Samples
 {
    public static Task Start_Server_With_WebSockets_Support()
    {
@@ -0,0 +1,75 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+// ReSharper disable UnusedType.Global
+// ReSharper disable UnusedMember.Global
+// ReSharper disable InconsistentNaming
+
+using System.Net;
+using System.Security.Cryptography;
+using System.Security.Cryptography.X509Certificates;
+using MQTTnet.Server;
+
+namespace MQTTnet.Samples.Server;
+
+public static class Server_TLS_Samples
+{
+    public static async Task Run_Server_With_Self_Signed_Certificate()
+    {
+        /*
+         * This sample starts a simple MQTT server which will accept any TCP connection.
+         * It also has an encrypted connection using a self signed TLS certificate.
+         *
+         * See sample "Run_Minimal_Server" for more details.
+         */
+
+        var mqttFactory = new MqttFactory();
+
+        // This certificate is self signed so that
+        var certificate = CreateSelfSignedCertificate("1.3.6.1.5.5.7.3.1");
+        
+        var mqttServerOptions = new MqttServerOptionsBuilder().WithEncryptionCertificate(certificate).WithEncryptedEndpoint().Build();
+
+        using (var mqttServer = mqttFactory.CreateMqttServer(mqttServerOptions))
+        {
+            await mqttServer.StartAsync();
+
+            Console.WriteLine("Press Enter to exit.");
+            Console.ReadLine();
+
+            // Stop and dispose the MQTT server if it is no longer needed!
+            await mqttServer.StopAsync();
+        }
+    }
+
+    static X509Certificate2 CreateSelfSignedCertificate(string oid)
+    {
+        var sanBuilder = new SubjectAlternativeNameBuilder();
+        sanBuilder.AddIpAddress(IPAddress.Loopback);
+        sanBuilder.AddIpAddress(IPAddress.IPv6Loopback);
+        sanBuilder.AddDnsName("localhost");
+
+        using (var rsa = RSA.Create())
+        {
+            var certRequest = new CertificateRequest("CN=localhost", rsa, HashAlgorithmName.SHA512, RSASignaturePadding.Pkcs1);
+
+            certRequest.CertificateExtensions.Add(
+                new X509KeyUsageExtension(X509KeyUsageFlags.DataEncipherment | X509KeyUsageFlags.KeyEncipherment | X509KeyUsageFlags.DigitalSignature, false));
+
+            certRequest.CertificateExtensions.Add(new X509EnhancedKeyUsageExtension(new OidCollection { new(oid) }, false));
+
+            certRequest.CertificateExtensions.Add(sanBuilder.Build());
+
+            using (var certificate = certRequest.CreateSelfSigned(DateTimeOffset.Now.AddMinutes(-10), DateTimeOffset.Now.AddMinutes(10)))
+            {
+                var pfxCertificate = new X509Certificate2(
+                    certificate.Export(X509ContentType.Pfx),
+                    (string)null!,
+                    X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.Exportable);
+
+                return pfxCertificate;
+            }
+        }
+    }
+}
@@ -103,7 +103,7 @@ namespace MQTTnet.AspNetCore.Tests
            connection.Transport = pipe;
            var ctx = new MqttConnectionContext(serializer, connection);

-            await ctx.SendPacketAsync(new MqttPublishPacket { Payload = new byte[20_000] }, CancellationToken.None).ConfigureAwait(false);
+            await ctx.SendPacketAsync(new MqttPublishPacket { PayloadSegment = new ArraySegment<byte>(new byte[20_000]) }, CancellationToken.None).ConfigureAwait(false);

            var readResult = await pipe.Send.Reader.ReadAsync();
            Assert.IsTrue(readResult.Buffer.Length > 20000);
@@ -19,7 +19,7 @@ namespace MQTTnet.AspNetCore.Tests
        {
            var serializer = new MqttPacketFormatterAdapter(MqttProtocolVersion.V311, new MqttBufferWriter(4096, 65535));

-            var buffer = serializer.Encode(new MqttPublishPacket {Topic = "a", Payload = new byte[5]}).Join();
+            var buffer = serializer.Encode(new MqttPublishPacket {Topic = "a", PayloadSegment = new byte[5]}).Join();

            var sequence = new ReadOnlySequence<byte>(buffer.Array, buffer.Offset, buffer.Count);

@@ -2,38 +2,34 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.

-using Microsoft.AspNetCore.Http;
-using MQTTnet.Adapter;
-using MQTTnet.Formatter;
-using MQTTnet.Implementations;
-using MQTTnet.Server;
 using System;
 using System.Net.WebSockets;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
+using MQTTnet.Formatter;
+using MQTTnet.Implementations;
+using MQTTnet.Server;

 namespace MQTTnet.AspNetCore
 {
    public sealed class MqttWebSocketServerAdapter : IMqttServerAdapter
    {
-        IMqttNetLogger _logger = new MqttNetNullLogger();
-        
+        IMqttNetLogger _logger = MqttNetNullLogger.Instance;
+
        public Func<IMqttChannelAdapter, Task> ClientHandler { get; set; }

-        public Task StartAsync(MqttServerOptions options, IMqttNetLogger logger)
+        public void Dispose()
        {
-            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
-            return Task.CompletedTask;
-        }
-
-        public Task StopAsync()
-        {
-            return Task.CompletedTask;
        }

        public async Task RunWebSocketConnectionAsync(WebSocket webSocket, HttpContext httpContext)
        {
-            if (webSocket == null) throw new ArgumentNullException(nameof(webSocket));
+            if (webSocket == null)
+            {
+                throw new ArgumentNullException(nameof(webSocket));
+            }

            var endpoint = $"{httpContext.Connection.RemoteIpAddress}:{httpContext.Connection.RemotePort}";

@@ -48,7 +44,7 @@ namespace MQTTnet.AspNetCore
                    var formatter = new MqttPacketFormatterAdapter(new MqttBufferWriter(4096, 65535));
                    var channel = new MqttWebSocketChannel(webSocket, endpoint, isSecureConnection, clientCertificate);

-                    using (var channelAdapter = new MqttChannelAdapter(channel, formatter, null, _logger))
+                    using (var channelAdapter = new MqttChannelAdapter(channel, formatter, _logger))
                    {
                        await clientHandler(channelAdapter).ConfigureAwait(false);
                    }
@@ -60,8 +56,15 @@ namespace MQTTnet.AspNetCore
            }
        }

-        public void Dispose()
+        public Task StartAsync(MqttServerOptions options, IMqttNetLogger logger)
        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+            return Task.CompletedTask;
+        }
+
+        public Task StopAsync()
+        {
+            return Task.CompletedTask;
        }
    }
 }
@@ -73,7 +73,7 @@ namespace MQTTnet.Benchmarks

            var channel = new MemoryMqttChannel(_stream);

-            _channelAdapter = new MqttChannelAdapter(channel, serializer, null, new MqttNetEventLogger());
+            _channelAdapter = new MqttChannelAdapter(channel, serializer, new MqttNetEventLogger());
        }

        static byte[] Join(params ArraySegment<byte>[] chunks)
@@ -30,17 +30,17 @@ namespace MQTTnet.Benchmarks
            
            var writer = new MqttBufferWriter(4096, 65535);
            writer.WriteString("A relative short string.");
-            writer.WriteBinaryData(_demoPayload);
+            writer.WriteBinary(_demoPayload);
            writer.WriteByte(0x01);
            writer.WriteByte(0x02);
            writer.WriteVariableByteInteger(5647382);
            writer.WriteString("A relative short string.");
            writer.WriteVariableByteInteger(8574489);
-            writer.WriteBinaryData(_demoPayload);
+            writer.WriteBinary(_demoPayload);
            writer.WriteByte(2);
            writer.WriteByte(0x02);
            writer.WriteString("fjgffiogfhgfhoihgoireghreghreguhreguireoghreouighreouighreughreguiorehreuiohruiorehreuioghreug");
-            writer.WriteBinaryData(_demoPayload);
+            writer.WriteBinary(_demoPayload);

            _readPayload = new ArraySegment<byte>(writer.GetBuffer(), 0, writer.Length).ToArray();
        }
@@ -83,11 +83,11 @@ namespace MQTTnet.Benchmarks
                writer.WriteVariableByteInteger(5647382);
                writer.WriteString("A relative short string.");
                writer.WriteVariableByteInteger(8574589);
-                writer.WriteBinaryData(_demoPayload);
+                writer.WriteBinary(_demoPayload);
                writer.WriteByte(2);
                writer.WriteByte(0x02);
                writer.WriteString("fjgffiogfhgfhoihgoireghreghreguhreguireoghreouighreouighreughreguiorehreuiohruiorehreuioghreug");
-                writer.WriteBinaryData(_demoPayload);
+                writer.WriteBinary(_demoPayload);

                writer.Reset(0);
            }
@@ -54,7 +54,7 @@ namespace MQTTnet.Benchmarks
        public void Deserialize_10000_Messages()
        {
            var channel = new BenchmarkMqttChannel(_serializedPacket);
-            var reader = new MqttChannelAdapter(channel, new MqttPacketFormatterAdapter(new MqttBufferWriter(4096, 65535)), null, new MqttNetEventLogger());
+            var reader = new MqttChannelAdapter(channel, new MqttPacketFormatterAdapter(new MqttBufferWriter(4096, 65535)), new MqttNetEventLogger());

            for (var i = 0; i < 10000; i++)
            {
@@ -15,12 +15,10 @@ namespace MQTTnet.Extensions.ManagedClient
        }

        public ManagedMqttApplicationMessage ApplicationMessage { get; }
-
+        
        /// <summary>
-        ///     Gets or sets the exception which was thrown while sending the message.
+        /// Then this is _null_ the message was processed successfully without any error.
        /// </summary>
        public Exception Exception { get; }
-
-        public bool HasFailed => Exception != null;
    }
-}
+}
@@ -6,13 +6,13 @@ using System;

 namespace MQTTnet.Extensions.ManagedClient
 {
-    public sealed class ApplicationMessageDroppedEventArgs : EventArgs
+    public sealed class ApplicationMessageSkippedEventArgs : EventArgs
    {
-        public ApplicationMessageDroppedEventArgs(ManagedMqttApplicationMessage applicationMessage)
+        public ApplicationMessageSkippedEventArgs(ManagedMqttApplicationMessage applicationMessage)
        {
            ApplicationMessage = applicationMessage ?? throw new ArgumentNullException(nameof(applicationMessage));
        }

        public ManagedMqttApplicationMessage ApplicationMessage { get; }
    }
-}
+}
@@ -1,7 +1,3 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
 using System;
 using MQTTnet.Client;

@@ -16,7 +12,7 @@ namespace MQTTnet.Extensions.ManagedClient
        }

        /// <summary>
-        ///     This is null when the server was not reachable and thus no MQTT response was transmitted.
+        /// This is null when the connection was failing and the server was not reachable.
        /// </summary>
        public MqttClientConnectResult ConnectResult { get; }

@@ -1,56 +1,52 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
 using System;
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Client;
+using MQTTnet.Packets;

 namespace MQTTnet.Extensions.ManagedClient
 {
    public interface IManagedMqttClient : IDisposable
    {
-        event Func<ApplicationMessageDroppedEventArgs, Task> ApplicationMessageDroppedAsync;
-
-        event Func<EventArgs, Task> ApplicationMessageEnqueueingAsync;
-
        event Func<ApplicationMessageProcessedEventArgs, Task> ApplicationMessageProcessedAsync;
-
+        
        event Func<MqttApplicationMessageReceivedEventArgs, Task> ApplicationMessageReceivedAsync;
-
+        
+        event Func<ApplicationMessageSkippedEventArgs, Task> ApplicationMessageSkippedAsync;
+        
        event Func<MqttClientConnectedEventArgs, Task> ConnectedAsync;
-
+        
        event Func<ConnectingFailedEventArgs, Task> ConnectingFailedAsync;
-
+        
+        event Func<EventArgs, Task> ConnectionStateChangedAsync;
+        
        event Func<MqttClientDisconnectedEventArgs, Task> DisconnectedAsync;
-
-        event Func<SubscribeProcessedEventArgs, Task> SubscribeProcessedAsync;
-
-        event Func<UnsubscribeProcessedEventArgs, Task> UnsubscribeProcessedAsync;
-
-        int EnqueuedApplicationMessagesCount { get; }
-
+        
+        event Func<ManagedProcessFailedEventArgs, Task> SynchronizingSubscriptionsFailedAsync;
+        
        IMqttClient InternalClient { get; }
-
+        
        bool IsConnected { get; }
-
+        
        bool IsStarted { get; }
-
+        
        ManagedMqttClientOptions Options { get; }
-
+        
+        int PendingApplicationMessagesCount { get; }
+        
        Task EnqueueAsync(MqttApplicationMessage applicationMessage);
-
+        
        Task EnqueueAsync(ManagedMqttApplicationMessage applicationMessage);
-
+        
        Task PingAsync(CancellationToken cancellationToken = default);
-
+        
        Task StartAsync(ManagedMqttClientOptions options);
-
-        Task StopAsync(MqttClientDisconnectOptions options, CancellationToken cancellationToken);
-
-        Task SubscribeAsync(MqttClientSubscribeOptions options);
-
-        Task UnsubscribeAsync(MqttClientUnsubscribeOptions options);
+        
+        Task StopAsync(bool cleanDisconnect = true);
+        
+        Task SubscribeAsync(ICollection<MqttTopicFilter> topicFilters);
+        
+        Task UnsubscribeAsync(ICollection<string> topics);
    }
 }
@@ -2,10 +2,9 @@

    <PropertyGroup>
        <TargetFrameworks>netstandard1.3;netstandard2.0;netstandard2.1;netcoreapp3.1;net5.0;net6.0;net7.0</TargetFrameworks>
-        <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net452;net461</TargetFrameworks>
+        <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net452;net461;net48</TargetFrameworks>
        <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' AND '$(MSBuildRuntimeType)' != 'Core' ">$(TargetFrameworks);uap10.0</TargetFrameworks>
-
-        <LangVersion>7.3</LangVersion>
+        
        <AssemblyName>MQTTnet.Extensions.ManagedClient</AssemblyName>
        <RootNamespace>MQTTnet.Extensions.ManagedClient</RootNamespace>
        <GeneratePackageOnBuild>True</GeneratePackageOnBuild>
@@ -1,4 +0,0 @@
-<wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
-	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=new/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=new_005Cevents/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=new_005Coptions/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>
@@ -6,16 +6,10 @@ using System;

 namespace MQTTnet.Extensions.ManagedClient
 {
-    public sealed class ManagedMqttApplicationMessage
+    public class ManagedMqttApplicationMessage
    {
-        public ManagedMqttApplicationMessage(string id, MqttApplicationMessage applicationMessage)
-        {
-            Id = id ?? throw new ArgumentNullException(nameof(id));
-            ApplicationMessage = applicationMessage ?? throw new ArgumentNullException(nameof(applicationMessage));
-        }
-        
-        public string Id { get; }
+        public Guid Id { get; set; } = Guid.NewGuid();

-        public MqttApplicationMessage ApplicationMessage { get; }
+        public MqttApplicationMessage ApplicationMessage { get; set; }
    }
 }
@@ -6,19 +6,15 @@ using System;

 namespace MQTTnet.Extensions.ManagedClient
 {
-    public sealed class ManagedMqttApplicationMessageBuilder
+    public class ManagedMqttApplicationMessageBuilder
    {
-        MqttApplicationMessage _applicationMessage;
-        string _id = Guid.NewGuid().ToString();
+        private Guid _id = Guid.NewGuid();
+        private MqttApplicationMessage _applicationMessage;

-        public ManagedMqttApplicationMessage Build()
+        public ManagedMqttApplicationMessageBuilder WithId(Guid id)
        {
-            if (_applicationMessage == null)
-            {
-                throw new InvalidOperationException("The ApplicationMessage cannot be null.");
-            }
-
-            return new ManagedMqttApplicationMessage(_id, _applicationMessage);
+            _id = id;
+            return this;
        }

        public ManagedMqttApplicationMessageBuilder WithApplicationMessage(MqttApplicationMessage applicationMessage)
@@ -29,10 +25,7 @@ namespace MQTTnet.Extensions.ManagedClient

        public ManagedMqttApplicationMessageBuilder WithApplicationMessage(Action<MqttApplicationMessageBuilder> builder)
        {
-            if (builder == null)
-            {
-                throw new ArgumentNullException(nameof(builder));
-            }
+            if (builder == null) throw new ArgumentNullException(nameof(builder));

            var internalBuilder = new MqttApplicationMessageBuilder();
            builder(internalBuilder);
@@ -41,16 +34,18 @@ namespace MQTTnet.Extensions.ManagedClient
            return this;
        }

-        public ManagedMqttApplicationMessageBuilder WithId(Guid id)
+        public ManagedMqttApplicationMessage Build()
        {
-            _id = id.ToString();
-            return this;
-        }
+            if (_applicationMessage == null)
+            {
+                throw new InvalidOperationException("The ApplicationMessage cannot be null.");
+            }

-        public ManagedMqttApplicationMessageBuilder WithId(string id)
-        {
-            _id = id ?? throw new ArgumentNullException(nameof(id));
-            return this;
+            return new ManagedMqttApplicationMessage
+            {
+                Id = _id,
+                ApplicationMessage = _applicationMessage
+            };
        }
    }
-}
+}
@@ -17,10 +17,10 @@ using MQTTnet.Server;

 namespace MQTTnet.Extensions.ManagedClient
 {
-    public sealed class ManagedMqttClient : Disposable
+    public sealed class ManagedMqttClient : Disposable, IManagedMqttClient
    {
        readonly AsyncEvent<ApplicationMessageProcessedEventArgs> _applicationMessageProcessedEvent = new AsyncEvent<ApplicationMessageProcessedEventArgs>();
-        readonly AsyncEvent<ApplicationMessageDroppedEventArgs> _applicationMessageSkippedEvent = new AsyncEvent<ApplicationMessageDroppedEventArgs>();
+        readonly AsyncEvent<ApplicationMessageSkippedEventArgs> _applicationMessageSkippedEvent = new AsyncEvent<ApplicationMessageSkippedEventArgs>();
        readonly AsyncEvent<ConnectingFailedEventArgs> _connectingFailedEvent = new AsyncEvent<ConnectingFailedEventArgs>();
        readonly AsyncEvent<EventArgs> _connectionStateChangedEvent = new AsyncEvent<EventArgs>();
        readonly AsyncEvent<ManagedProcessFailedEventArgs> _synchronizingSubscriptionsFailedEvent = new AsyncEvent<ManagedProcessFailedEventArgs>();
@@ -76,7 +76,7 @@ namespace MQTTnet.Extensions.ManagedClient
            _logger = logger.WithSource(nameof(ManagedMqttClient));
        }

-        public event Func<ApplicationMessageDroppedEventArgs, Task> ApplicationMessageSkippedAsync
+        public event Func<ApplicationMessageSkippedEventArgs, Task> ApplicationMessageSkippedAsync
        {
            add => _applicationMessageSkippedEvent.AddHandler(value);
            remove => _applicationMessageSkippedEvent.RemoveHandler(value);
@@ -118,18 +118,12 @@ namespace MQTTnet.Extensions.ManagedClient
            remove => InternalClient.DisconnectedAsync -= value;
        }

-        public event Func<SubscribeProcessedEventArgs, Task> SubscribeProcessedAsync;
-        
-        public event Func<UnsubscribeProcessedEventArgs, Task> UnsubscribeProcessedAsync;
-
-        public event Func<ManagedProcessFailedEventArgs, Task> SubscribedAsync
+        public event Func<ManagedProcessFailedEventArgs, Task> SynchronizingSubscriptionsFailedAsync
        {
            add => _synchronizingSubscriptionsFailedEvent.AddHandler(value);
            remove => _synchronizingSubscriptionsFailedEvent.RemoveHandler(value);
        }

-        public event Func<EventArgs, Task> ApplicationMessageEnqueued;
-
        public IMqttClient InternalClient { get; }

        public bool IsConnected => InternalClient.IsConnected;
@@ -170,7 +164,7 @@ namespace MQTTnet.Extensions.ManagedClient
            MqttTopicValidator.ThrowIfInvalid(applicationMessage.ApplicationMessage);

            ManagedMqttApplicationMessage removedMessage = null;
-            ApplicationMessageDroppedEventArgs applicationMessageDroppedEventArgs = null;
+            ApplicationMessageSkippedEventArgs applicationMessageSkippedEventArgs = null;

            try
            {
@@ -181,7 +175,7 @@ namespace MQTTnet.Extensions.ManagedClient
                        if (Options.PendingMessagesOverflowStrategy == MqttPendingMessagesOverflowStrategy.DropNewMessage)
                        {
                            _logger.Verbose("Skipping publish of new application message because internal queue is full.");
-                            applicationMessageDroppedEventArgs = new ApplicationMessageDroppedEventArgs(applicationMessage);
+                            applicationMessageSkippedEventArgs = new ApplicationMessageSkippedEventArgs(applicationMessage);
                            return;
                        }

@@ -189,7 +183,7 @@ namespace MQTTnet.Extensions.ManagedClient
                        {
                            removedMessage = _messageQueue.RemoveFirst();
                            _logger.Verbose("Removed oldest application message from internal queue because it is full.");
-                            applicationMessageDroppedEventArgs = new ApplicationMessageDroppedEventArgs(removedMessage);
+                            applicationMessageSkippedEventArgs = new ApplicationMessageSkippedEventArgs(removedMessage);
                        }
                    }

@@ -208,9 +202,9 @@ namespace MQTTnet.Extensions.ManagedClient
            }
            finally
            {
-                if (applicationMessageDroppedEventArgs != null && _applicationMessageSkippedEvent.HasHandlers)
+                if (applicationMessageSkippedEventArgs != null && _applicationMessageSkippedEvent.HasHandlers)
                {
-                    await _applicationMessageSkippedEvent.InvokeAsync(applicationMessageDroppedEventArgs).ConfigureAwait(false);
+                    await _applicationMessageSkippedEvent.InvokeAsync(applicationMessageSkippedEventArgs).ConfigureAwait(false);
                }
            }
        }
@@ -359,13 +353,13 @@ namespace MQTTnet.Extensions.ManagedClient
            return remainingTime < TimeSpan.Zero ? TimeSpan.Zero : remainingTime;
        }

-        async Task HandleSubscriptionExceptionAsync(Exception exception)
+        async Task HandleSubscriptionExceptionAsync(Exception exception, List<MqttTopicFilter> addedSubscriptions, List<string> removedSubscriptions)
        {
            _logger.Warning(exception, "Synchronizing subscriptions failed.");

            if (_synchronizingSubscriptionsFailedEvent.HasHandlers)
            {
-                await _synchronizingSubscriptionsFailedEvent.InvokeAsync(new ManagedProcessFailedEventArgs(exception)).ConfigureAwait(false);
+                await _synchronizingSubscriptionsFailedEvent.InvokeAsync(new ManagedProcessFailedEventArgs(exception, addedSubscriptions, removedSubscriptions)).ConfigureAwait(false);
            }
        }

@@ -463,11 +457,13 @@ namespace MQTTnet.Extensions.ManagedClient
        {
            _logger.Info("Publishing subscriptions at reconnect");

+            List<MqttTopicFilter> topicFilters = null;
+
            try
            {
                if (_reconnectSubscriptions.Any())
                {
-                    var topicFilters = new List<MqttTopicFilter>();
+                    topicFilters = new List<MqttTopicFilter>();

                    foreach (var sub in _reconnectSubscriptions)
                    {
@@ -485,7 +481,7 @@ namespace MQTTnet.Extensions.ManagedClient
            }
            catch (Exception exception)
            {
-                await HandleSubscriptionExceptionAsync(exception).ConfigureAwait(false);
+                await HandleSubscriptionExceptionAsync(exception, topicFilters, null).ConfigureAwait(false);
            }
        }

@@ -597,6 +593,9 @@ namespace MQTTnet.Extensions.ManagedClient
                    }

                    await InternalClient.UnsubscribeAsync(unsubscribeOptionsBuilder.Build()).ConfigureAwait(false);
+
+                    //clear because these worked, maybe the subscribe below will fail, only report those
+                    removedSubscriptions.Clear();
                }

                if (addedSubscriptions != null && addedSubscriptions.Any())
@@ -613,7 +612,7 @@ namespace MQTTnet.Extensions.ManagedClient
            }
            catch (Exception exception)
            {
-                await HandleSubscriptionExceptionAsync(exception).ConfigureAwait(false);
+                await HandleSubscriptionExceptionAsync(exception, addedSubscriptions, removedSubscriptions).ConfigureAwait(false);
            }
        }

@@ -3,9 +3,8 @@
 // See the LICENSE file in the project root for more information.

 using System;
-using System.Threading;
+using System.Collections.Generic;
 using System.Threading.Tasks;
-using MQTTnet.Client;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;

@@ -39,35 +38,6 @@ namespace MQTTnet.Extensions.ManagedClient
            return managedMqttClient.EnqueueAsync(applicationMessage);
        }

-        public static Task StopAsync(this IManagedMqttClient managedMqttClient, bool isClean = true, CancellationToken cancellationToken = default)
-        {
-            if (managedMqttClient == null)
-            {
-                throw new ArgumentNullException(nameof(managedMqttClient));
-            }
-
-            return managedMqttClient.StopAsync(new MqttClientDisconnectOptions
-            {
-                IsClean = isClean
-            }, cancellationToken);
-        }
-        
-        public static Task SubscribeAsync(this IManagedMqttClient managedMqttClient, MqttTopicFilter topicFilter)
-        {
-            if (managedMqttClient == null)
-            {
-                throw new ArgumentNullException(nameof(managedMqttClient));
-            }
-
-            if (topicFilter == null)
-            {
-                throw new ArgumentNullException(nameof(topicFilter));
-            }
-
-            var subscribeOptions = new MqttClientSubscribeOptionsBuilder().WithTopicFilter(topicFilter).Build();
-            return managedMqttClient.SubscribeAsync(subscribeOptions);
-        }
-
        public static Task SubscribeAsync(
            this IManagedMqttClient managedMqttClient,
            string topic,
@@ -83,8 +53,11 @@ namespace MQTTnet.Extensions.ManagedClient
                throw new ArgumentNullException(nameof(topic));
            }

-            var subscribeOptions = new MqttClientSubscribeOptionsBuilder().WithTopicFilter(topic, qualityOfServiceLevel).Build();
-            return managedMqttClient.SubscribeAsync(subscribeOptions);
+            return managedMqttClient.SubscribeAsync(
+                new List<MqttTopicFilter>
+                {
+                    new MqttTopicFilterBuilder().WithTopic(topic).WithQualityOfServiceLevel(qualityOfServiceLevel).Build()
+                });
        }

        public static Task UnsubscribeAsync(this IManagedMqttClient managedMqttClient, string topic)
@@ -99,8 +72,7 @@ namespace MQTTnet.Extensions.ManagedClient
                throw new ArgumentNullException(nameof(topic));
            }

-            var unsubscribeOptions = new MqttClientUnsubscribeOptionsBuilder().WithTopicFilter(topic).Build();
-            return managedMqttClient.UnsubscribeAsync(unsubscribeOptions);
+            return managedMqttClient.UnsubscribeAsync(new List<string> { topic });
        }
    }
 }
@@ -10,15 +10,6 @@ namespace MQTTnet.Extensions.ManagedClient
 {
    public sealed class ManagedMqttClientOptions
    {
-        public ManagedMqttClientOptions()
-        {
-        }
-
-        public ManagedMqttClientOptions(MqttClientOptions clientOptions)
-        {
-            ClientOptions = clientOptions;
-        }
-        
        public MqttClientOptions ClientOptions { get; set; }

        public TimeSpan AutoReconnectDelay { get; set; } = TimeSpan.FromSeconds(5);
@@ -33,7 +24,7 @@ namespace MQTTnet.Extensions.ManagedClient

        /// <summary>
        /// Defines the maximum amount of topic filters which will be sent in a SUBSCRIBE/UNSUBSCRIBE packet.
-        /// Amazon AWS limits this number to 8. The default is int.MaxValue.
+        /// Amazon Web Services (AWS) limits this number to 8. The default is int.MaxValue.
        /// </summary>
        public int MaxTopicFiltersInSubscribeUnsubscribePackets { get; set; } = int.MaxValue;
    }
@@ -8,7 +8,7 @@ using MQTTnet.Server;

 namespace MQTTnet.Extensions.ManagedClient
 {
-    public sealed class ManagedMqttClientOptionsBuilder
+    public class ManagedMqttClientOptionsBuilder
    {
        readonly ManagedMqttClientOptions _options = new ManagedMqttClientOptions();
        MqttClientOptionsBuilder _clientOptionsBuilder;
@@ -0,0 +1,34 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using MQTTnet.Packets;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace MQTTnet.Extensions.ManagedClient
+{
+    public class ManagedProcessFailedEventArgs : EventArgs
+    {
+        public ManagedProcessFailedEventArgs(Exception exception, List<MqttTopicFilter> addedSubscriptions, List<string> removedSubscriptions)
+        {
+            Exception = exception ?? throw new ArgumentNullException(nameof(exception));
+
+            if (addedSubscriptions != null)
+            {
+                AddedSubscriptions = new List<string>(addedSubscriptions.Select(item => item.Topic));
+            }
+
+            if (removedSubscriptions != null)
+            {
+                RemovedSubscriptions = new List<string>(removedSubscriptions);
+            }
+        }
+
+        public Exception Exception { get; }
+
+        public List<string> AddedSubscriptions { get; }
+        public List<string> RemovedSubscriptions { get; }
+    }
+}
@@ -10,21 +10,6 @@ namespace MQTTnet.Extensions.ManagedClient
 {
    public static class MqttFactoryExtensions
    {
-        public static IManagedMqttClient CreateManagedMqttClient(this MqttFactory factory, IMqttClient mqttClient, IMqttNetLogger logger)
-        {
-            if (factory == null)
-            {
-                throw new ArgumentNullException(nameof(factory));
-            }
-
-            if (mqttClient == null)
-            {
-                return new NewManagedMqttClient(factory.CreateMqttClient(), logger);
-            }
-
-            return new NewManagedMqttClient(mqttClient, logger);
-        }
-
        public static IManagedMqttClient CreateManagedMqttClient(this MqttFactory factory, IMqttClient mqttClient = null)
        {
            if (factory == null)
@@ -34,10 +19,10 @@ namespace MQTTnet.Extensions.ManagedClient

            if (mqttClient == null)
            {
-                return new NewManagedMqttClient(factory.CreateMqttClient(), factory.DefaultLogger);
+                return new ManagedMqttClient(factory.CreateMqttClient(), factory.DefaultLogger);
            }

-            return new NewManagedMqttClient(mqttClient, factory.DefaultLogger);
+            return new ManagedMqttClient(mqttClient, factory.DefaultLogger);
        }

        public static IManagedMqttClient CreateManagedMqttClient(this MqttFactory factory, IMqttNetLogger logger)
@@ -52,10 +37,10 @@ namespace MQTTnet.Extensions.ManagedClient
                throw new ArgumentNullException(nameof(logger));
            }

-            return new NewManagedMqttClient(factory.CreateMqttClient(logger), logger);
+            return new ManagedMqttClient(factory.CreateMqttClient(logger), logger);
        }

-        public static ManagedMqttClientOptionsBuilder CreateManagedMqttClientOptionsBuilder(this MqttFactory factory)
+        public static ManagedMqttClientOptionsBuilder CreateManagedMqttClientOptionsBuilder(this MqttFactory _)
        {
            return new ManagedMqttClientOptionsBuilder();
        }
@@ -1,95 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Collections.Generic;
-using System.Threading.Tasks;
-using MQTTnet.Client;
-using MQTTnet.Diagnostics;
-using MQTTnet.Internal;
-
-namespace MQTTnet.Extensions.ManagedClient
-{
-    public sealed class ApplicationMessagesManager
-    {
-        readonly MqttNetSourceLogger _logger;
-
-        readonly Queue<ManagedMqttApplicationMessage> _messageQueue = new Queue<ManagedMqttApplicationMessage>();
-        readonly IMqttClient _mqttClient;
-
-        public ApplicationMessagesManager(IMqttClient mqttClient, IMqttNetLogger logger)
-        {
-            _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
-
-            if (logger == null)
-            {
-                throw new ArgumentNullException(nameof(logger));
-            }
-
-            _logger = logger.WithSource<ApplicationMessagesManager>();
-        }
-
-        public AsyncEvent<ApplicationMessageDroppedEventArgs> ApplicationMessageDroppedEvent { get; } = new AsyncEvent<ApplicationMessageDroppedEventArgs>();
-
-        public AsyncEvent<ApplicationMessageEnqueueingEventArgs> ApplicationMessageEnqueueingEvent { get; } = new AsyncEvent<ApplicationMessageEnqueueingEventArgs>();
-
-        public int EnqueuedApplicationMessagesCount
-        {
-            get
-            {
-                lock (_messageQueue)
-                {
-                    return _messageQueue.Count;
-                }
-            }
-        }
-
-        public void Dequeue()
-        {
-            lock (_messageQueue)
-            {
-                _messageQueue.Dequeue();
-            }
-        }
-
-        public async Task Enqueue(ManagedMqttApplicationMessage applicationMessage)
-        {
-            if (applicationMessage == null)
-            {
-                throw new ArgumentNullException(nameof(applicationMessage));
-            }
-
-            // Fire the event first so that the handler can make sure that this message is 
-            // properly backed up in a suitable storage.
-            if (ApplicationMessageEnqueueingEvent.HasHandlers)
-            {
-                var eventArgs = new ApplicationMessageEnqueueingEventArgs(applicationMessage, 0);
-                await ApplicationMessageEnqueueingEvent.InvokeAsync(eventArgs).ConfigureAwait(false);
-            }
-
-            lock (_messageQueue)
-            {
-                
-                // TODO: Drop if too much!
-                
-                _messageQueue.Enqueue(applicationMessage);
-            }
-        }
-
-        public bool TryPeek(out ManagedMqttApplicationMessage applicationMessage)
-        {
-            lock (_messageQueue)
-            {
-                if (_messageQueue.Count == 0)
-                {
-                    applicationMessage = null;
-                    return false;
-                }
-
-                applicationMessage = _messageQueue.Peek();
-                return true;
-            }
-        }
-    }
-}
@@ -1,21 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-
-namespace MQTTnet.Extensions.ManagedClient
-{
-    public sealed class ApplicationMessageEnqueueingEventArgs : EventArgs
-    {
-        public ApplicationMessageEnqueueingEventArgs(ManagedMqttApplicationMessage applicationMessage, ushort packetIdentifier)
-        {
-            ApplicationMessage = applicationMessage ?? throw new ArgumentNullException(nameof(applicationMessage));
-            PacketIdentifier = packetIdentifier;
-        }
-
-        public ManagedMqttApplicationMessage ApplicationMessage { get; }
-
-        public ushort PacketIdentifier { get; }
-    }
-}
@@ -1,18 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-
-namespace MQTTnet.Extensions.ManagedClient
-{
-    public class ManagedProcessFailedEventArgs : EventArgs
-    {
-        public ManagedProcessFailedEventArgs(Exception exception)
-        {
-            Exception = exception ?? throw new ArgumentNullException(nameof(exception));
-        }
-
-        public Exception Exception { get; }
-    }
-}
@@ -1,27 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Collections.Generic;
-using MQTTnet.Client;
-using MQTTnet.Packets;
-
-namespace MQTTnet.Extensions.ManagedClient
-{
-    public sealed class SubscribeProcessedEventArgs : EventArgs
-    {
-        public SubscribeProcessedEventArgs(MqttClientSubscribeOptions options, MqttClientSubscribeResultCode result, IReadOnlyCollection<MqttUserProperty> userProperties)
-        {
-            Options = options ?? throw new ArgumentNullException(nameof(options));
-            Result = result;
-            UserProperties = userProperties;
-        }
-
-        public MqttClientSubscribeOptions Options { get; }
-
-        public MqttClientSubscribeResultCode Result { get; }
-
-        public IReadOnlyCollection<MqttUserProperty> UserProperties { get; }
-    }
-}
@@ -1,27 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Collections.Generic;
-using MQTTnet.Client;
-using MQTTnet.Packets;
-
-namespace MQTTnet.Extensions.ManagedClient
-{
-    public sealed class UnsubscribeProcessedEventArgs : EventArgs
-    {
-        public UnsubscribeProcessedEventArgs(MqttClientUnsubscribeOptions options, MqttClientUnsubscribeResultCode result, IReadOnlyCollection<MqttUserProperty> userProperties)
-        {
-            Options = options ?? throw new ArgumentNullException(nameof(options));
-            Result = result;
-            UserProperties = userProperties;
-        }
-
-        public MqttClientUnsubscribeOptions Options { get; }
-
-        public MqttClientUnsubscribeResultCode Result { get; }
-
-        public IReadOnlyCollection<MqttUserProperty> UserProperties { get; }
-    }
-}
@@ -1,15 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-namespace MQTTnet.Extensions.ManagedClient
-{
-    public enum MaintainConnectionResult
-    {
-        NoChange,
-
-        ConnectedEstablished,
-
-        NotConnected
-    }
-}
@@ -1,35 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Linq;
-using MQTTnet.Client;
-
-namespace MQTTnet.Extensions.ManagedClient
-{
-    public sealed class ManagedMqttSubscription
-    {
-        public ManagedMqttSubscription(MqttClientSubscribeOptions subscribeOptions)
-        {
-            SubscribeOptions = subscribeOptions ?? throw new ArgumentNullException(nameof(subscribeOptions));
-
-            Topic = subscribeOptions.TopicFilters.First().Topic;
-        }
-
-        public bool IsObsolete => UnsubscribeOptions != null;
-
-        public bool IsPending { get; set; } = true;
-
-        public MqttClientSubscribeOptions SubscribeOptions { get; }
-
-        public string Topic { get; }
-
-        public MqttClientUnsubscribeOptions UnsubscribeOptions { get; private set; }
-
-        public void MarkAsUnsubscribed(MqttClientUnsubscribeOptions options)
-        {
-            UnsubscribeOptions = options ?? throw new ArgumentNullException(nameof(options));
-        }
-    }
-}
@@ -1,155 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Client;
-using MQTTnet.Diagnostics;
-using MQTTnet.Internal;
-using MQTTnet.Protocol;
-
-namespace MQTTnet.Extensions.ManagedClient
-{
-    public sealed class ManagedMqttSubscriptionsManager
-    {
-        readonly MqttNetSourceLogger _logger;
-        readonly IMqttClient _mqttClient;
-        
-        // Do not use a dictionary in order to preserve subscription ordering (retained messages).
-        readonly List<ManagedMqttSubscription> _subscriptions = new List<ManagedMqttSubscription>();
-
-        public ManagedMqttSubscriptionsManager(IMqttClient mqttClient, IMqttNetLogger logger)
-        {
-            _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
-
-            if (logger == null)
-            {
-                throw new ArgumentNullException(nameof(logger));
-            }
-
-            _logger = logger.WithSource<ManagedMqttSubscriptionsManager>();
-        }
-
-        public AsyncEvent<SubscribeProcessedEventArgs> SubscribeProcessedEvent { get; } = new AsyncEvent<SubscribeProcessedEventArgs>();
-
-        public AsyncEvent<UnsubscribeProcessedEventArgs> UnsubscribeProcessedEvent { get; } = new AsyncEvent<UnsubscribeProcessedEventArgs>();
-
-        public void ResubscribeAll()
-        {
-            lock (_subscriptions)
-            {
-                foreach (var subscription in _subscriptions)
-                {
-                    subscription.IsPending = true;
-                }
-            }
-        }
-
-        public void Subscribe(MqttClientSubscribeOptions options)
-        {
-            if (options == null)
-            {
-                throw new ArgumentNullException(nameof(options));
-            }
-
-            if (options.TopicFilters.Count > 1)
-            {
-                throw new NotSupportedException("The managed client only supports subscribing to one topic at the same time.");
-            }
-
-            var topic = options.TopicFilters.First().Topic;
-            
-            lock (_subscriptions)
-            {
-                MqttTopicValidator.ThrowIfInvalidSubscribe(topic);
-
-                _subscriptions.RemoveAll(s => s.Topic.Equals(topic));
-                _subscriptions.Add(new ManagedMqttSubscription(options));
-            }
-        }
-
-        public async Task Synchronize(CancellationToken cancellationToken)
-        {
-            // TODO: Remember real changes.
-
-            List<ManagedMqttSubscription> pendingSubscriptions;
-            List<ManagedMqttSubscription> obsoleteSubscriptions;
-            lock (_subscriptions)
-            {
-                pendingSubscriptions = _subscriptions.Where(s => s.IsPending).ToList();
-                obsoleteSubscriptions = _subscriptions.Where(s => s.IsObsolete).ToList();
-            }
-
-            if (pendingSubscriptions.Count == 0 && obsoleteSubscriptions.Count == 0)
-            {
-                _logger.Verbose("No subscriptions to synchronize");
-                return;
-            }
-
-            foreach (var subscription in pendingSubscriptions)
-            {
-                var subscribeResult = await _mqttClient.SubscribeAsync(subscription.SubscribeOptions, cancellationToken).ConfigureAwait(false);
-                subscription.IsPending = false;
-                await FireSubscribeProcessedEvent(subscription, subscribeResult).ConfigureAwait(false);
-            }
-
-            foreach (var subscription in obsoleteSubscriptions)
-            {
-                var unsubscribeResult = await _mqttClient.UnsubscribeAsync(subscription.UnsubscribeOptions, cancellationToken).ConfigureAwait(false);
-                lock (_subscriptions)
-                {
-                    _subscriptions.Remove(subscription);
-                }
-
-                await FireUnsubscribeProcessedEvent(subscription, unsubscribeResult).ConfigureAwait(false);
-            }
-        }
-
-        public void Unsubscribe(MqttClientUnsubscribeOptions options)
-        {
-            if (options == null)
-            {
-                throw new ArgumentNullException(nameof(options));
-            }
-
-            lock (_subscriptions)
-            {
-                var topic = options.TopicFilters.First();
-                var existingSubscription = _subscriptions.FirstOrDefault(s => s.Topic.Equals(topic));
-
-                if (existingSubscription != null)
-                {
-                    existingSubscription.MarkAsUnsubscribed(options);
-                }
-            }
-        }
-
-        async Task FireSubscribeProcessedEvent(ManagedMqttSubscription subscription, MqttClientSubscribeResult subscribeResult)
-        {
-            _logger.Info("Subscribed topic '{0}'.", subscription.Topic);
-
-            if (SubscribeProcessedEvent.HasHandlers)
-            {
-                var resultCode = subscribeResult?.Items.First().ResultCode ?? MqttClientSubscribeResultCode.UnspecifiedError;
-                var eventArgs = new SubscribeProcessedEventArgs(subscription.SubscribeOptions, resultCode, subscribeResult?.UserProperties);
-                await SubscribeProcessedEvent.InvokeAsync(eventArgs).ConfigureAwait(false);
-            }
-        }
-
-        async Task FireUnsubscribeProcessedEvent(ManagedMqttSubscription subscription, MqttClientUnsubscribeResult unsubscribeResult)
-        {
-            _logger.Info("Unsubscribed topic '{0}'.", subscription.Topic);
-
-            if (UnsubscribeProcessedEvent.HasHandlers)
-            {
-                var resultCode = unsubscribeResult?.Items.First().ResultCode ?? MqttClientUnsubscribeResultCode.UnspecifiedError;
-                var eventArgs = new UnsubscribeProcessedEventArgs(subscription.UnsubscribeOptions, resultCode, unsubscribeResult?.UserProperties);
-                await UnsubscribeProcessedEvent.InvokeAsync(eventArgs).ConfigureAwait(false);
-            }
-        }
-    }
-}
@@ -1,103 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Client;
-using MQTTnet.Diagnostics;
-using MQTTnet.Internal;
-
-namespace MQTTnet.Extensions.ManagedClient
-{
-    public sealed class MqttConnectionManager
-    {
-        readonly MqttNetSourceLogger _logger;
-        readonly IMqttClient _mqttClient;
-
-        bool _wasConnected;
-
-        public MqttConnectionManager(IMqttClient mqttClient, IMqttNetLogger logger)
-        {
-            _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
-
-            if (logger == null)
-            {
-                throw new ArgumentNullException(nameof(logger));
-            }
-
-            _logger = logger.WithSource<MqttConnectionManager>();
-
-            _mqttClient.DisconnectedAsync += OnClientDisconnected;
-        }
-
-        public AsyncEvent<MqttClientConnectedEventArgs> ConnectedEvent { get; } = new AsyncEvent<MqttClientConnectedEventArgs>();
-
-        public AsyncEvent<ConnectingFailedEventArgs> ConnectingFailedEvent { get; } = new AsyncEvent<ConnectingFailedEventArgs>();
-
-        public AsyncEvent<MqttClientDisconnectedEventArgs> DisconnectedEvent { get; } = new AsyncEvent<MqttClientDisconnectedEventArgs>();
-
-        public async Task<MaintainConnectionResult> MaintainConnection(ManagedMqttClientOptions options, CancellationToken cancellationToken)
-        {
-            cancellationToken.ThrowIfCancellationRequested();
-            
-            if (_wasConnected)
-            {
-                try
-                {
-                    // The only valid way for testing the connection is to send a PING. So we start with this
-                    // in order to check if reconnecting etc. is require or not.
-                    await _mqttClient.PingAsync(cancellationToken).ConfigureAwait(false);
-
-                    // The client is properly connection. No further action required.
-                    return MaintainConnectionResult.NoChange;
-                }
-                catch (Exception exception)
-                {
-                    _logger.Error(exception, "Error while checking connection.");
-                }
-            }
-
-            MqttClientConnectResult connectResult = null;
-            try
-            {
-                // The PING was not successful so that there is no working connection. So we connect.
-                connectResult = await _mqttClient.ConnectAsync(options.ClientOptions, cancellationToken).ConfigureAwait(false);
-
-                _wasConnected = true;
-                _logger.Info("Connected.");
-
-                if (ConnectedEvent.HasHandlers)
-                {
-                    var eventArgs = new MqttClientConnectedEventArgs(connectResult);
-                    await ConnectedEvent.TryInvokeAsync(eventArgs, _logger).ConfigureAwait(false);
-                }
-
-                return MaintainConnectionResult.ConnectedEstablished;
-            }
-            catch (Exception exception)
-            {
-                if (!(exception is OperationCanceledException))
-                {
-                    _logger.Error(exception, "Error while connecting.");
-                }
-
-                if (ConnectingFailedEvent.HasHandlers)
-                {
-                    var eventArgs = new ConnectingFailedEventArgs(connectResult, exception);
-                    await ConnectingFailedEvent.InvokeAsync(eventArgs).ConfigureAwait(false);
-                }
-            }
-
-            _wasConnected = false;
-            return MaintainConnectionResult.NotConnected;
-        }
-
-        Task OnClientDisconnected(MqttClientDisconnectedEventArgs arg)
-        {
-            _wasConnected = false;
-            return DisconnectedEvent?.InvokeAsync(arg);
-        }
-    }
-}
@@ -1,309 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Threading;
-using System.Threading.Tasks;
-using MQTTnet.Client;
-using MQTTnet.Diagnostics;
-using MQTTnet.Internal;
-
-namespace MQTTnet.Extensions.ManagedClient
-{
-    public sealed class NewManagedMqttClient : Disposable, IManagedMqttClient
-    {
-        readonly AsyncEvent<ApplicationMessageProcessedEventArgs> _applicationMessageProcessedEvent = new AsyncEvent<ApplicationMessageProcessedEventArgs>();
-        readonly ApplicationMessagesManager _applicationMessagesManager;
-        readonly MqttConnectionManager _connectionManager;
-        readonly AsyncEvent<EventArgs> _isConnectedChangedEvent = new AsyncEvent<EventArgs>();
-        readonly MqttNetSourceLogger _logger;
-        readonly ManagedMqttSubscriptionsManager _subscriptionsManager;
-
-        readonly ManualResetEventSlim _workSignal = new ManualResetEventSlim();
-
-        CancellationTokenSource _workerCancellationToken;
-        Task _workerTask;
-
-        public NewManagedMqttClient(IMqttClient mqttClient, IMqttNetLogger logger)
-        {
-            InternalClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
-
-            if (logger == null)
-            {
-                throw new ArgumentNullException(nameof(logger));
-            }
-
-            InternalClient.DisconnectedAsync += OnInternalClientDisconnected;
-
-            _logger = logger.WithSource(nameof(NewManagedMqttClient));
-
-            _connectionManager = new MqttConnectionManager(mqttClient, logger);
-            _subscriptionsManager = new ManagedMqttSubscriptionsManager(mqttClient, logger);
-            _applicationMessagesManager = new ApplicationMessagesManager(mqttClient, logger);
-
-            // TODO: Start timer for periodical connection checking.
-        }
-
-        public event Func<EventArgs, Task> ApplicationMessageEnqueueingAsync
-        {
-            add => _applicationMessagesManager.ApplicationMessageEnqueueingEvent.AddHandler(value);
-            remove => _applicationMessagesManager.ApplicationMessageEnqueueingEvent.RemoveHandler(value);
-        }
-
-        public event Func<ApplicationMessageProcessedEventArgs, Task> ApplicationMessageProcessedAsync
-        {
-            add => _applicationMessageProcessedEvent.AddHandler(value);
-            remove => _applicationMessageProcessedEvent.RemoveHandler(value);
-        }
-
-        public event Func<MqttApplicationMessageReceivedEventArgs, Task> ApplicationMessageReceivedAsync
-        {
-            add => InternalClient.ApplicationMessageReceivedAsync += value;
-            remove => InternalClient.ApplicationMessageReceivedAsync += value;
-        }
-
-        public event Func<ApplicationMessageDroppedEventArgs, Task> ApplicationMessageDroppedAsync
-        {
-            add => _applicationMessagesManager.ApplicationMessageDroppedEvent.AddHandler(value);
-            remove => _applicationMessagesManager.ApplicationMessageDroppedEvent.RemoveHandler(value);
-        }
-
-        public event Func<MqttClientConnectedEventArgs, Task> ConnectedAsync
-        {
-            add => _connectionManager.ConnectedEvent.AddHandler(value);
-            remove => _connectionManager.ConnectedEvent.RemoveHandler(value);
-        }
-
-        public event Func<ConnectingFailedEventArgs, Task> ConnectingFailedAsync
-        {
-            add => _connectionManager.ConnectingFailedEvent.AddHandler(value);
-            remove => _connectionManager.ConnectingFailedEvent.RemoveHandler(value);
-        }
-
-        public event Func<MqttClientDisconnectedEventArgs, Task> DisconnectedAsync
-        {
-            add => _connectionManager.DisconnectedEvent.AddHandler(value);
-            remove => _connectionManager.DisconnectedEvent.RemoveHandler(value);
-        }
-
-        public event Func<SubscribeProcessedEventArgs, Task> SubscribeProcessedAsync
-        {
-            add => _subscriptionsManager.SubscribeProcessedEvent.AddHandler(value);
-            remove => _subscriptionsManager.SubscribeProcessedEvent.RemoveHandler(value);
-        }
-
-        public event Func<UnsubscribeProcessedEventArgs, Task> UnsubscribeProcessedAsync
-        {
-            add => _subscriptionsManager.UnsubscribeProcessedEvent.AddHandler(value);
-            remove => _subscriptionsManager.UnsubscribeProcessedEvent.RemoveHandler(value);
-        }
-
-        public IMqttClient InternalClient { get; }
-
-        public bool IsConnected { get; private set; }
-
-        public bool IsStarted { get; private set; }
-
-        public ManagedMqttClientOptions Options { get; private set; }
-
-        public int EnqueuedApplicationMessagesCount => _applicationMessagesManager.EnqueuedApplicationMessagesCount;
-
-        public Task EnqueueAsync(MqttApplicationMessage applicationMessage)
-        {
-            return EnqueueAsync(new ManagedMqttApplicationMessage(Guid.NewGuid().ToString(), applicationMessage));
-        }
-
-        public async Task EnqueueAsync(ManagedMqttApplicationMessage applicationMessage)
-        {
-            if (applicationMessage == null)
-            {
-                throw new ArgumentNullException(nameof(applicationMessage));
-            }
-
-            await _applicationMessagesManager.Enqueue(applicationMessage).ConfigureAwait(false);
-            _workSignal.Set();
-        }
-
-        public Task PingAsync(CancellationToken cancellationToken = default)
-        {
-            return InternalClient.PingAsync(cancellationToken);
-        }
-
-        public Task StartAsync(ManagedMqttClientOptions options)
-        {
-            Options = options ?? throw new ArgumentNullException(nameof(options));
-
-            _workerCancellationToken = new CancellationTokenSource();
-
-            _workerTask = Task.Factory.StartNew(
-                () => WorkerLoop(_workerCancellationToken.Token),
-                _workerCancellationToken.Token,
-                TaskCreationOptions.PreferFairness,
-                TaskScheduler.Default);
-
-            _workSignal.Set();
-
-            return CompletedTask.Instance;
-        }
-
-        public async Task StopAsync(MqttClientDisconnectOptions options, CancellationToken cancellationToken = default)
-        {
-            if (options == null)
-            {
-                throw new ArgumentNullException(nameof(options));
-            }
-
-            // TODO: Send proper Disconnect signal.
-
-            try
-            {
-                await InternalClient.DisconnectAsync(options, cancellationToken).ConfigureAwait(false);
-            }
-            catch (Exception exception)
-            {
-                _logger.Error(exception, "Error while disconnecting.");
-            }
-
-            _workerCancellationToken?.Cancel(false);
-            _workerCancellationToken?.Dispose();
-
-            _workerCancellationToken = null;
-
-            if (_workerTask != null)
-            {
-            }
-        }
-
-        public Task SubscribeAsync(MqttClientSubscribeOptions options)
-        {
-            ThrowIfDisposed();
-
-            _subscriptionsManager.Subscribe(options);
-            _workSignal.Set();
-
-            return CompletedTask.Instance;
-        }
-
-        public Task UnsubscribeAsync(MqttClientUnsubscribeOptions options)
-        {
-            ThrowIfDisposed();
-
-            _subscriptionsManager.Unsubscribe(options);
-            _workSignal.Set();
-
-            return CompletedTask.Instance;
-        }
-
-        protected override void Dispose(bool disposing)
-        {
-            base.Dispose(disposing);
-
-            if (disposing)
-            {
-            }
-        }
-
-        Task OnInternalClientDisconnected(MqttClientDisconnectedEventArgs eventArgs)
-        {
-            _workSignal.Set();
-            return CompletedTask.Instance;
-        }
-
-        async Task UpdateConnectionStatus(MaintainConnectionResult maintainConnectionResult)
-        {
-            var isConnected = maintainConnectionResult != MaintainConnectionResult.NotConnected;
-
-            if (IsConnected.Equals(isConnected))
-            {
-                return;
-            }
-
-            IsConnected = isConnected;
-
-            if (_isConnectedChangedEvent.HasHandlers)
-            {
-                await _isConnectedChangedEvent.InvokeAsync(EventArgs.Empty).ConfigureAwait(false);
-            }
-        }
-
-        async Task WorkerLoop(CancellationToken cancellationToken)
-        {
-            try
-            {
-                IsStarted = true;
-
-                while (!cancellationToken.IsCancellationRequested)
-                {
-                    _workSignal.Wait(cancellationToken);
-                    _workSignal.Reset();
-
-                    var maintainConnectionResult = await _connectionManager.MaintainConnection(Options, cancellationToken).ConfigureAwait(false);
-                    await UpdateConnectionStatus(maintainConnectionResult).ConfigureAwait(false);
-
-                    if (maintainConnectionResult == MaintainConnectionResult.ConnectedEstablished && Options.ClientOptions.CleanSession)
-                    {
-                        // Since the session is clean the server will now know any subscription so that
-                        // we have to subscribe to all of them again.
-                        _subscriptionsManager.ResubscribeAll();
-                    }
-
-                    if (IsConnected)
-                    {
-                        await _subscriptionsManager.Synchronize(cancellationToken).ConfigureAwait(false);
-                    }
-
-                    if (IsConnected)
-                    {
-                        // TODO: Move into pending messages manager + locking.
-                        while (_applicationMessagesManager.TryPeek(out var nextPendingMessage))
-                        {
-                            Exception processingException = null;
-                            try
-                            {
-                                _logger.Verbose("Publishing managed application message {0}.", nextPendingMessage.Id);
-
-                                await InternalClient.PublishAsync(nextPendingMessage.ApplicationMessage, cancellationToken).ConfigureAwait(false);
-
-                                // The message was delivered successfully. So we can get rid of it.
-                                _applicationMessagesManager.Dequeue();
-                            }
-                            catch (Exception exception)
-                            {
-                                processingException = exception;
-                            }
-                            finally
-                            {
-                                if (_applicationMessageProcessedEvent.HasHandlers)
-                                {
-                                    var eventArgs = new ApplicationMessageProcessedEventArgs(nextPendingMessage, processingException);
-                                    await _applicationMessageProcessedEvent.InvokeAsync(eventArgs).ConfigureAwait(false);
-                                }
-                            }
-                        }
-                    }
-                }
-            }
-            catch (OperationCanceledException)
-            {
-            }
-#if !NETSTANDARD1_3
-            catch (ThreadAbortException)
-            {
-            }
-#endif
-            catch (Exception exception)
-            {
-                _logger.Error(exception, "Error while maintaining connection.");
-            }
-            finally
-            {
-                IsStarted = false;
-
-                await UpdateConnectionStatus(MaintainConnectionResult.NotConnected).ConfigureAwait(false);
-            }
-
-            // TODO: Disconnected!
-        }
-    }
-}
@@ -2,7 +2,7 @@

    <PropertyGroup>
        <TargetFrameworks>netstandard1.3;netstandard2.0;netstandard2.1;netcoreapp3.1;net5.0;net6.0;net7.0</TargetFrameworks>
-        <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net452;net461</TargetFrameworks>
+        <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net452;net461;net48</TargetFrameworks>
        <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' AND '$(MSBuildRuntimeType)' != 'Core' ">$(TargetFrameworks);uap10.0</TargetFrameworks>
        
        <AssemblyName>MQTTnet.Extensions.Rpc</AssemblyName>
@@ -4,6 +4,7 @@

 using System;
 using System.Collections.Concurrent;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Client;
@@ -119,7 +120,6 @@ namespace MQTTnet.Extensions.Rpc
            finally
            {
                _waitingCalls.TryRemove(responseTopic, out _);
-
                await _mqttClient.UnsubscribeAsync(responseTopic, CancellationToken.None).ConfigureAwait(false);
            }
        }
@@ -131,7 +131,8 @@ namespace MQTTnet.Extensions.Rpc
                return CompletedTask.Instance;
            }

-            awaitable.TrySetResult(eventArgs.ApplicationMessage.Payload);
+            var payloadBuffer = eventArgs.ApplicationMessage.PayloadSegment.ToArray();
+            awaitable.TrySetResult(payloadBuffer);

            // Set this message to handled to that other code can avoid execution etc.
            eventArgs.IsHandled = true;
@@ -2,7 +2,7 @@

    <PropertyGroup>
        <TargetFrameworks>netstandard1.3;netstandard2.0;netstandard2.1;netcoreapp3.1;net5.0;net6.0;net7.0</TargetFrameworks>
-        <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net452;net461</TargetFrameworks>
+        <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net452;net461;net48</TargetFrameworks>
        <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' AND '$(MSBuildRuntimeType)' != 'Core' ">$(TargetFrameworks);uap10.0</TargetFrameworks>
        
        <AssemblyName>MQTTnet.Extensions.WebSocket4Net</AssemblyName>
@@ -27,8 +27,10 @@ namespace MQTTnet.Extensions.WebSocket4Net
                    return new MqttChannelAdapter(
                        new MqttTcpChannel(options),
                        new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttBufferWriter(options.WriterBufferSize, options.WriterBufferSizeMax)),
-                        packetInspector,
-                        logger);
+                        logger)
+                    {
+                        PacketInspector = packetInspector
+                    };
                }

                case MqttClientWebSocketOptions webSocketOptions:
@@ -36,8 +38,10 @@ namespace MQTTnet.Extensions.WebSocket4Net
                    return new MqttChannelAdapter(
                        new WebSocket4NetMqttChannel(options, webSocketOptions),
                        new MqttPacketFormatterAdapter(options.ProtocolVersion, new MqttBufferWriter(options.WriterBufferSize, options.WriterBufferSizeMax)),
-                        packetInspector,
-                        logger);
+                        logger)
+                    {
+                        PacketInspector = packetInspector
+                    };
                }

                default:
@@ -33,9 +33,18 @@ namespace MQTTnet.TestApp

                client.ApplicationMessageReceivedAsync += e =>
                {
+                    var payloadText = string.Empty;
+                    if (e.ApplicationMessage.PayloadSegment.Count > 0)
+                    {
+                        payloadText = Encoding.UTF8.GetString(
+                            e.ApplicationMessage.PayloadSegment.Array,
+                            e.ApplicationMessage.PayloadSegment.Offset,
+                            e.ApplicationMessage.PayloadSegment.Count);
+                    }
+                    
                    Console.WriteLine("### RECEIVED APPLICATION MESSAGE ###");
                    Console.WriteLine($"+ Topic = {e.ApplicationMessage.Topic}");
-                    Console.WriteLine($"+ Payload = {Encoding.UTF8.GetString(e.ApplicationMessage.Payload)}");
+                    Console.WriteLine($"+ Payload = {payloadText}");
                    Console.WriteLine($"+ QoS = {e.ApplicationMessage.QualityOfServiceLevel}");
                    Console.WriteLine($"+ Retain = {e.ApplicationMessage.Retain}");
                    Console.WriteLine();
@@ -196,7 +196,7 @@ namespace MQTTnet.TestApp
            return new MqttApplicationMessage
            {
                Topic = "A/B/C",
-                Payload = Encoding.UTF8.GetBytes(Payload),
+                PayloadSegment = new ArraySegment<byte>(Encoding.UTF8.GetBytes(Payload)),
                QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce
            };
        }
@@ -229,7 +229,7 @@ namespace MQTTnet.TestApp
                var message = new MqttApplicationMessage
                {
                    Topic = "A/B/C",
-                    Payload = Encoding.UTF8.GetBytes("Hello World"),
+                    PayloadSegment = new ArraySegment<byte>(Encoding.UTF8.GetBytes("Hello World")),
                    QualityOfServiceLevel = MqttQualityOfServiceLevel.ExactlyOnce
                };

@@ -280,7 +280,7 @@ namespace MQTTnet.TestApp
                var message = new MqttApplicationMessage
                {
                    Topic = "A/B/C",
-                    Payload = Encoding.UTF8.GetBytes("Hello World"),
+                    PayloadSegment = new ArraySegment<byte>(Encoding.UTF8.GetBytes("Hello World")),
                    QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce
                };

@@ -331,7 +331,7 @@ namespace MQTTnet.TestApp
                var message = new MqttApplicationMessage
                {
                    Topic = "A/B/C",
-                    Payload = Encoding.UTF8.GetBytes("Hello World"),
+                    PayloadSegment = new ArraySegment<byte>(Encoding.UTF8.GetBytes("Hello World")),
                    QualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce
                };

@@ -5,6 +5,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using MQTTnet.Diagnostics;
@@ -100,7 +101,7 @@ namespace MQTTnet.TestApp
                    {
                        // Replace the payload with the timestamp. But also extending a JSON 
                        // based payload with the timestamp is a suitable use case.
-                        e.ApplicationMessage.Payload = Encoding.UTF8.GetBytes(DateTime.Now.ToString("O"));
+                        e.ApplicationMessage.PayloadSegment = new ArraySegment<byte>(Encoding.UTF8.GetBytes(DateTime.Now.ToString("O")));
                    }

                    if (e.ApplicationMessage.Topic == "not_allowed_topic")
@@ -143,10 +144,16 @@ namespace MQTTnet.TestApp
                
                mqttServer.InterceptingPublishAsync += e =>
                {
-                    MqttNetConsoleLogger.PrintToConsole(
-                        $"'{e.ClientId}' reported '{e.ApplicationMessage.Topic}' > '{Encoding.UTF8.GetString(e.ApplicationMessage.Payload ?? new byte[0])}'",
-                        ConsoleColor.Magenta);
+                    var payloadText = string.Empty;
+                    if (e.ApplicationMessage.PayloadSegment.Count > 0)
+                    {
+                        payloadText = Encoding.UTF8.GetString(
+                            e.ApplicationMessage.PayloadSegment.Array,
+                            e.ApplicationMessage.PayloadSegment.Offset,
+                            e.ApplicationMessage.PayloadSegment.Count);
+                    }
                    
+                    MqttNetConsoleLogger.PrintToConsole($"'{e.ClientId}' reported '{e.ApplicationMessage.Topic}' > '{payloadText}'", ConsoleColor.Magenta);
                    return CompletedTask.Instance;
                };

@@ -1,178 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Threading;
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Extensions.ManagedClient;
-using MQTTnet.Internal;
-
-namespace MQTTnet.Tests.ManagedMqttClient
-{
-    [TestClass]
-    public sealed class ManagedMqttClient_Event_Tests : BaseTestClass
-    {
-        [TestMethod]
-        public async Task Connecting_Should_Fire_Event()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                await testEnvironment.StartServer();
-
-                var managedClient = testEnvironment.CreateManagedClient();
-
-                var eventFired = false;
-                managedClient.ConnectedAsync += e =>
-                {
-                    eventFired = true;
-                    return CompletedTask.Instance;
-                };
-
-                await managedClient.StartAsync(testEnvironment.CreateDefaultManagedMqttClientOptions());
-
-                await LongTestDelay();
-
-                Assert.IsTrue(eventFired);
-            }
-        }
-
-        [TestMethod]
-        public async Task Connecting_To_Invalid_Server_Should_Fire_Event()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                testEnvironment.IgnoreClientLogErrors = true;
-
-                var managedClient = testEnvironment.CreateManagedMqttClient();
-
-                ConnectingFailedEventArgs connectingFailedEventArgs = null;
-                managedClient.ConnectingFailedAsync += args =>
-                {
-                    connectingFailedEventArgs = args;
-                    return CompletedTask.Instance;
-                };
-
-                await managedClient.StartAsync(
-                    new ManagedMqttClientOptions
-                    {
-                        ClientOptions = testEnvironment.Factory.CreateClientOptionsBuilder().WithTimeout(TimeSpan.FromSeconds(2)).WithTcpServer("wrong_server", 1234).Build()
-                    });
-
-                SpinWait.SpinUntil(() => connectingFailedEventArgs != null, 10000);
-
-                // The wrong server must be reported in general.
-                Assert.IsNotNull(connectingFailedEventArgs);
-                Assert.IsNotNull(connectingFailedEventArgs.Exception);
-                Assert.IsNull(connectingFailedEventArgs.ConnectResult);
-            }
-        }
-
-        [TestMethod]
-        public async Task Disconnect_Should_Fire_Event()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                var server = await testEnvironment.StartServer();
-
-                var managedClient = testEnvironment.CreateManagedClient();
-
-                var eventFired = false;
-                managedClient.DisconnectedAsync += e =>
-                {
-                    eventFired = true;
-                    return CompletedTask.Instance;
-                };
-
-                await managedClient.StartAsync(testEnvironment.CreateDefaultManagedMqttClientOptions());
-
-                await LongTestDelay();
-
-                await server.StopAsync();
-
-                await LongTestDelay();
-
-                Assert.IsTrue(eventFired);
-            }
-        }
-
-        [TestMethod]
-        public async Task Enqueueing_Should_Fire_Event()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                await testEnvironment.StartServer();
-
-                var managedClient = testEnvironment.CreateManagedClient();
-
-                var eventFired = false;
-                managedClient.ApplicationMessageEnqueueingAsync += e =>
-                {
-                    eventFired = true;
-                    return CompletedTask.Instance;
-                };
-
-                await managedClient.EnqueueAsync("A");
-
-                Assert.IsTrue(eventFired);
-            }
-        }
-
-        [TestMethod]
-        public async Task Subscription_Should_Fire_Event()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                await testEnvironment.StartServer();
-
-                var managedClient = testEnvironment.CreateManagedClient();
-
-                await managedClient.SubscribeAsync("A");
-
-                var eventFired = false;
-                managedClient.SubscribeProcessedAsync += e =>
-                {
-                    eventFired = e.Options.TopicFilters[0].Topic == "A";
-                    return CompletedTask.Instance;
-                };
-
-                await managedClient.StartAsync(testEnvironment.CreateDefaultManagedMqttClientOptions());
-
-                await LongTestDelay();
-
-                Assert.IsTrue(eventFired);
-            }
-        }
-
-        [TestMethod]
-        public async Task Unsubscription_Should_Fire_Event()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                await testEnvironment.StartServer();
-
-                var managedClient = testEnvironment.CreateManagedClient();
-
-                await managedClient.SubscribeAsync("A");
-
-                var eventFired = false;
-                managedClient.UnsubscribeProcessedAsync += e =>
-                {
-                    eventFired = e.Options.TopicFilters[0] == "A";
-                    return CompletedTask.Instance;
-                };
-
-                await managedClient.StartAsync(testEnvironment.CreateDefaultManagedMqttClientOptions());
-
-                await LongTestDelay();
-
-                await managedClient.UnsubscribeAsync("A");
-
-                await LongTestDelay();
-
-                Assert.IsTrue(eventFired);
-            }
-        }
-    }
-}
@@ -1,135 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Extensions.ManagedClient;
-using MQTTnet.Implementations;
-using MQTTnet.Internal;
-using MQTTnet.Server;
-
-namespace MQTTnet.Tests.ManagedMqttClient
-{
-    [TestClass]
-    public sealed class ManagedMqttClient_Messages_Tests : BaseTestClass
-    {
-        [TestMethod]
-        public async Task Drop_New_Messages_On_Full_Queue()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                await testEnvironment.StartServer();
-
-                var managedClient = testEnvironment.CreateManagedMqttClient();
-
-                var clientOptions = new ManagedMqttClientOptionsBuilder().WithClientOptions(o => o.WithTcpServer("localhost"))
-                    .WithMaxPendingMessages(5)
-                    .WithPendingMessagesOverflowStrategy(MqttPendingMessagesOverflowStrategy.DropNewMessage);
-
-                await managedClient.StartAsync(clientOptions.Build());
-
-                await managedClient.EnqueueAsync("1");
-                await managedClient.EnqueueAsync("2");
-                await managedClient.EnqueueAsync("3");
-                await managedClient.EnqueueAsync("4");
-                await managedClient.EnqueueAsync("5");
-                await managedClient.EnqueueAsync("6");
-                await managedClient.EnqueueAsync("7");
-                await managedClient.EnqueueAsync("8");
-
-                Assert.AreEqual(5, managedClient.EnqueuedApplicationMessagesCount);
-            }
-        }
-
-        [TestMethod]
-        public async Task Drop_Old_Messages_On_Full_Queue()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                await testEnvironment.StartServer();
-
-                var managedClient = testEnvironment.CreateManagedMqttClient();
-
-                var clientOptions = new ManagedMqttClientOptionsBuilder().WithClientOptions(o => o.WithTcpServer("localhost"))
-                    .WithMaxPendingMessages(5)
-                    .WithPendingMessagesOverflowStrategy(MqttPendingMessagesOverflowStrategy.DropOldestQueuedMessage);
-
-                await managedClient.StartAsync(clientOptions.Build());
-
-                await managedClient.EnqueueAsync("1");
-                await managedClient.EnqueueAsync("2");
-                await managedClient.EnqueueAsync("3");
-                await managedClient.EnqueueAsync("4");
-                await managedClient.EnqueueAsync("5");
-                await managedClient.EnqueueAsync("6");
-                await managedClient.EnqueueAsync("7");
-                await managedClient.EnqueueAsync("8");
-
-                Assert.AreEqual(5, managedClient.EnqueuedApplicationMessagesCount);
-            }
-        }
-
-        [TestMethod]
-        public async Task Preserve_Order_Of_Subscriptions()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                var server = await testEnvironment.StartServer();
-
-                // Prepare the retained messages.
-                await server.InjectApplicationMessage(testEnvironment.Factory.CreateApplicationMessageBuilder().WithTopic("A").WithPayload("P").WithRetainFlag().Build());
-                await server.InjectApplicationMessage(testEnvironment.Factory.CreateApplicationMessageBuilder().WithTopic("B").WithPayload("P").WithRetainFlag().Build());
-                await server.InjectApplicationMessage(testEnvironment.Factory.CreateApplicationMessageBuilder().WithTopic("C").WithPayload("P").WithRetainFlag().Build());
-                await server.InjectApplicationMessage(testEnvironment.Factory.CreateApplicationMessageBuilder().WithTopic("3").WithPayload("P").WithRetainFlag().Build());
-                await server.InjectApplicationMessage(testEnvironment.Factory.CreateApplicationMessageBuilder().WithTopic("2").WithPayload("P").WithRetainFlag().Build());
-                await server.InjectApplicationMessage(testEnvironment.Factory.CreateApplicationMessageBuilder().WithTopic("1").WithPayload("P").WithRetainFlag().Build());
-
-                // Subscribe to the retained messages in a defined order.
-                var managedClient = testEnvironment.CreateManagedMqttClient();
-
-                var applicationMessages = new List<MqttApplicationMessage>();
-                managedClient.ApplicationMessageReceivedAsync += e =>
-                {
-                    applicationMessages.Add(e.ApplicationMessage);
-                    return CompletedTask.Instance;
-                };
-
-                await managedClient.SubscribeAsync("B");
-                await managedClient.SubscribeAsync("C");
-                await managedClient.SubscribeAsync("A");
-                await managedClient.SubscribeAsync("2");
-                await managedClient.SubscribeAsync("1");
-                await managedClient.SubscribeAsync("3");
-
-                await managedClient.StartAsync(testEnvironment.CreateDefaultManagedMqttClientOptions()).ConfigureAwait(false);
-
-                await LongTestDelay();
-
-                var order = string.Join(string.Empty, applicationMessages.Select(a => a.Topic));
-
-                Assert.AreEqual("BCA213", order);
-            }
-        }
-
-        [TestMethod]
-        public async Task Publish()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                testEnvironment.TrackServerReceivedApplicationMessages = true;
-                await testEnvironment.StartServer();
-
-                var managedClient = await testEnvironment.StartManagedClient();
-
-                await managedClient.EnqueueAsync(testEnvironment.Factory.CreateApplicationMessageBuilder().WithTopic("TEST").Build());
-
-                await LongTestDelay();
-
-                Assert.AreEqual(1, testEnvironment.ServerReceivedApplicationMessages.Count);
-            }
-        }
-    }
-}
@@ -9,6 +9,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
+using MQTTnet.Diagnostics;
 using MQTTnet.Extensions.ManagedClient;
 using MQTTnet.Formatter;
 using MQTTnet.Internal;
@@ -19,17 +20,111 @@ using MQTTnet.Tests.Mockups;
 namespace MQTTnet.Tests.Clients.ManagedMqttClient
 {
    [TestClass]
-    public sealed class ManagedMqttClient_Connection_Tests : BaseTestClass
+    public sealed class ManagedMqttClient_Tests : BaseTestClass
    {
+        [TestMethod]
+        public async Task Expose_Custom_Connection_Error()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                var server = await testEnvironment.StartServer();
+                
+                server.ValidatingConnectionAsync += args =>
+                {
+                    args.ReasonCode = MqttConnectReasonCode.BadUserNameOrPassword;
+                    return CompletedTask.Instance;
+                };
+
+                var managedClient = testEnvironment.Factory.CreateManagedMqttClient();
+
+                MqttClientDisconnectedEventArgs disconnectedArgs = null;
+                managedClient.DisconnectedAsync += args =>
+                {
+                    disconnectedArgs = args;
+                    return CompletedTask.Instance;
+                };
+                
+                var clientOptions = testEnvironment.Factory.CreateManagedMqttClientOptionsBuilder().WithClientOptions(testEnvironment.CreateDefaultClientOptions()).Build();
+                await managedClient.StartAsync(clientOptions);
+
+                await LongTestDelay();
+
+                Assert.IsNotNull(disconnectedArgs);
+                Assert.AreEqual(MqttClientConnectResultCode.BadUserNameOrPassword, disconnectedArgs.ConnectResult.ResultCode);
+            }
+        }
+        
+        [TestMethod]
+        public async Task Receive_While_Not_Cleanly_Disconnected()
+        {
+            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
+            {
+                await testEnvironment.StartServer(o => o.WithPersistentSessions());
+
+                var senderClient = await testEnvironment.ConnectClient();
+
+                // Prepare managed client.
+                var managedClient = testEnvironment.Factory.CreateManagedMqttClient();
+                await managedClient.SubscribeAsync("#");
+                var receivedMessages = testEnvironment.CreateApplicationMessageHandler(managedClient);
+                
+                var managedClientOptions = new ManagedMqttClientOptions
+                {
+                    ClientOptions = testEnvironment.Factory.CreateClientOptionsBuilder()
+                        .WithTcpServer("127.0.0.1", testEnvironment.ServerPort)
+                        .WithClientId(nameof(Receive_While_Not_Cleanly_Disconnected) + "_managed")
+                        .WithCleanSession(false)
+                        .Build()
+                };
+
+                await managedClient.StartAsync(managedClientOptions);
+                await LongTestDelay();
+                await LongTestDelay();
+                
+                // Send test data.
+                await senderClient.PublishStringAsync("topic1");
+                await LongTestDelay();
+                await LongTestDelay();
+                
+                receivedMessages.AssertReceivedCountEquals(1);
+
+                // Stop the managed client but keep session at server (not clean disconnect required).
+                await managedClient.StopAsync(false);
+                await LongTestDelay();
+                
+                // Send new messages in the meantime.
+                await senderClient.PublishStringAsync("topic2", qualityOfServiceLevel: MqttQualityOfServiceLevel.ExactlyOnce);
+                await LongTestDelay();
+                
+                // Start the managed client, it should receive the new message.
+                await managedClient.StartAsync(managedClientOptions);
+                await LongTestDelay();
+                
+                receivedMessages.AssertReceivedCountEquals(2);
+                
+                // Stop and start again, no new message should be received.
+                for (var i = 0; i < 3; i++)
+                {
+                    await managedClient.StopAsync(false);
+                    await LongTestDelay();
+                    await managedClient.StartAsync(managedClientOptions);
+                    await LongTestDelay();
+                }
+
+                receivedMessages.AssertReceivedCountEquals(2);
+            }
+        }
+
        [TestMethod]
        public async Task Connect_To_Invalid_Server()
        {
            using (var testEnvironment = CreateTestEnvironment())
            {
-                await testEnvironment.StartServer();
-                await LongTestDelay();
+                testEnvironment.IgnoreClientLogErrors = true;

-                var managedClient = testEnvironment.Factory.CreateManagedMqttClient(testEnvironment.CreateClient());
+                var mqttClient = testEnvironment.CreateClient();
+
+                var managedClient = testEnvironment.Factory.CreateManagedMqttClient(mqttClient);

                ConnectingFailedEventArgs connectingFailedEventArgs = null;
                managedClient.ConnectingFailedAsync += args =>
@@ -56,63 +151,76 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
        }

        [TestMethod]
-        public async Task Receive_While_Not_Cleanly_Disconnected()
+        public async Task Drop_New_Messages_On_Full_Queue()
        {
-            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
+            var factory = new MqttFactory();
+            var managedClient = factory.CreateManagedMqttClient();
+            try
            {
-                await testEnvironment.StartServer(o => o.WithPersistentSessions());
+                var clientOptions = new ManagedMqttClientOptionsBuilder().WithMaxPendingMessages(5)
+                    .WithPendingMessagesOverflowStrategy(MqttPendingMessagesOverflowStrategy.DropNewMessage);

-                var senderClient = await testEnvironment.ConnectClient();
+                clientOptions.WithClientOptions(o => o.WithTcpServer("localhost"));

-                // Prepare managed client.
-                var managedClient = testEnvironment.Factory.CreateManagedMqttClient();
-                await managedClient.SubscribeAsync("#");
-                var receivedMessages = testEnvironment.CreateApplicationMessageHandler(managedClient);
+                await managedClient.StartAsync(clientOptions.Build());

-                var managedClientOptions = new ManagedMqttClientOptions
+                await managedClient.EnqueueAsync("1");
+                await managedClient.EnqueueAsync("2");
+                await managedClient.EnqueueAsync("3");
+                await managedClient.EnqueueAsync("4");
+                await managedClient.EnqueueAsync("5");
+                await managedClient.EnqueueAsync("6");
+                await managedClient.EnqueueAsync("7");
+                await managedClient.EnqueueAsync("8");
+
+                Assert.AreEqual(5, managedClient.PendingApplicationMessagesCount);
+            }
+            finally
+            {
+                await managedClient.StopAsync();
+            }
+        }
+
+        [TestMethod]
+        public async Task ManagedClients_Will_Message_Send()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                await testEnvironment.StartServer();
+
+                var receivedMessagesCount = 0;
+
+                var clientOptions = new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort)
+                    .WithWillTopic("My/last/will")
+                    .WithWillQualityOfServiceLevel(MqttQualityOfServiceLevel.AtMostOnce)
+                    .Build();
+
+                var dyingClient = testEnvironment.CreateClient();
+                var dyingManagedClient = new MQTTnet.Extensions.ManagedClient.ManagedMqttClient(dyingClient, testEnvironment.ClientLogger);
+
+                await dyingManagedClient.StartAsync(new ManagedMqttClientOptionsBuilder().WithClientOptions(clientOptions).Build());
+
+                // Wait until the managed client is fully set up and running.
+                await Task.Delay(1000);
+
+                var receivingClient = await testEnvironment.ConnectClient();
+
+                receivingClient.ApplicationMessageReceivedAsync += e =>
                {
-                    ClientOptions = testEnvironment.Factory.CreateClientOptionsBuilder()
-                        .WithTcpServer("127.0.0.1", testEnvironment.ServerPort)
-                        .WithClientId(nameof(Receive_While_Not_Cleanly_Disconnected) + "_managed")
-                        .WithCleanSession(false)
-                        .Build()
+                    Interlocked.Increment(ref receivedMessagesCount);
+                    return CompletedTask.Instance;
                };

-                await managedClient.StartAsync(managedClientOptions);
-                await LongTestDelay();
-                await LongTestDelay();
+                await receivingClient.SubscribeAsync("My/last/will");

-                // Send test data.
-                await senderClient.PublishStringAsync("topic1");
-                await LongTestDelay();
-                await LongTestDelay();
+                // Disposing the client will not sent a DISCONNECT packet so that connection is terminated
+                // which will lead to the will publish.
+                dyingManagedClient.Dispose();

-                receivedMessages.AssertReceivedCountEquals(1);
+                // Wait for arrival of the will message at the receiver.
+                await Task.Delay(5000);

-                // Stop the managed client but keep session at server (not clean disconnect required).
-                await managedClient.StopAsync(false);
-                await LongTestDelay();
-
-                // Send new messages in the meantime.
-                await senderClient.PublishStringAsync("topic2", qualityOfServiceLevel: MqttQualityOfServiceLevel.ExactlyOnce);
-                await LongTestDelay();
-
-                // Start the managed client, it should receive the new message.
-                await managedClient.StartAsync(managedClientOptions);
-                await LongTestDelay();
-
-                receivedMessages.AssertReceivedCountEquals(2);
-
-                // Stop and start again, no new message should be received.
-                for (var i = 0; i < 3; i++)
-                {
-                    await managedClient.StopAsync(false);
-                    await LongTestDelay();
-                    await managedClient.StartAsync(managedClientOptions);
-                    await LongTestDelay();
-                }
-
-                receivedMessages.AssertReceivedCountEquals(2);
+                Assert.AreEqual(1, receivedMessagesCount);
            }
        }

@@ -123,18 +231,18 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
            {
                var server = await testEnvironment.StartServer();

-                var managedClient = testEnvironment.CreateManagedClient();
+                var managedClient = new MQTTnet.Extensions.ManagedClient.ManagedMqttClient(testEnvironment.CreateClient(), new MqttNetEventLogger());
                var clientOptions = new MqttClientOptionsBuilder().WithTcpServer("localhost", testEnvironment.ServerPort);

                var connected = GetConnectedTask(managedClient);

-                await managedClient.StartAsync(testEnvironment.CreateDefaultManagedMqttClientOptions());
+                await managedClient.StartAsync(new ManagedMqttClientOptionsBuilder().WithClientOptions(clientOptions).Build());

                await connected;

                await managedClient.StopAsync();

-                await LongTestDelay();
+                await Task.Delay(500);

                Assert.AreEqual(0, (await server.GetClientsAsync()).Count);
            }
@@ -150,7 +258,7 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient

                await testEnvironment.StartServer();

-                var managedClient = testEnvironment.CreateManagedClient();
+                var managedClient = new MQTTnet.Extensions.ManagedClient.ManagedMqttClient(testEnvironment.CreateClient(), new MqttNetEventLogger());
                var clientOptions = new MqttClientOptionsBuilder().WithTcpServer("localhost", testEnvironment.ServerPort);
                var storage = new ManagedMqttClientTestStorage();

@@ -190,8 +298,6 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
        {
            using (var testEnvironment = CreateTestEnvironment())
            {
-                await testEnvironment.StartServer();
-
                var unmanagedClient = testEnvironment.CreateClient();
                var managedClient = await CreateManagedClientAsync(testEnvironment, unmanagedClient);

@@ -208,7 +314,7 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
                await managedClient.SubscribeAsync("unsubscribedThenSubscribed");

                //wait a bit for the subscriptions to become established before the messages are published
-                await LongTestDelay();
+                await Task.Delay(500);

                var sendingClient = await testEnvironment.ConnectClient();

@@ -238,7 +344,7 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
                await connected;

                // wait a bit so that the managed client can reestablish the subscriptions
-                await LongTestDelay();
+                await Task.Delay(500);

                received = SetupReceivingOfMessages(managedClient, 2);

@@ -254,7 +360,7 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
        {
            using (var testEnvironment = CreateTestEnvironment())
            {
-                var server = await testEnvironment.StartServer().ConfigureAwait(false);
+                await testEnvironment.StartServer().ConfigureAwait(false);

                var sendingClient = await testEnvironment.ConnectClient().ConfigureAwait(false);
                await sendingClient.PublishStringAsync("topic", "A", retain: true);
@@ -264,12 +370,12 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient

                await sendingClient.DisconnectAsync();

-                // Prepare retained messages.
-                await server.InjectApplicationMessage(testEnvironment.Factory.CreateApplicationMessageBuilder().WithTopic("topic").WithPayload("payload").WithRetainFlag().Build());
-
                // Now use the managed client and check if subscriptions get cleared properly.
-                var receivedManagedMessages = new List<MqttApplicationMessage>();

+                var clientOptions = new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort);
+
+                var receivedManagedMessages = new List<MqttApplicationMessage>();
+                
                var managedClient = testEnvironment.Factory.CreateManagedMqttClient(testEnvironment.CreateClient());
                managedClient.ApplicationMessageReceivedAsync += e =>
                {
@@ -279,10 +385,7 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient

                await managedClient.SubscribeAsync("topic");

-                var managedClientOptions = testEnvironment.CreateDefaultManagedMqttClientOptions();
-                managedClientOptions.ClientOptions.CleanSession = false;
-                await managedClient.StartAsync(managedClientOptions);
-
+                await managedClient.StartAsync(new ManagedMqttClientOptionsBuilder().WithClientOptions(clientOptions).WithAutoReconnectDelay(TimeSpan.FromSeconds(0.5)).Build());
                await LongTestDelay();

                Assert.AreEqual(1, receivedManagedMessages.Count);
@@ -290,8 +393,7 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
                await managedClient.StopAsync();
                await LongTestDelay();

-                await managedClient.StartAsync(managedClientOptions);
-
+                await managedClient.StartAsync(new ManagedMqttClientOptionsBuilder().WithClientOptions(clientOptions).WithAutoReconnectDelay(TimeSpan.FromSeconds(0.5)).Build());
                await LongTestDelay();

                // After reconnect and then some delay, the retained message must not be received,
@@ -301,7 +403,7 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
                // Make sure that it gets received after subscribing again.
                await managedClient.SubscribeAsync("topic");
                await LongTestDelay();
-
+                
                Assert.AreEqual(2, receivedManagedMessages.Count);
            }
        }
@@ -313,13 +415,12 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
        {
            using (var testEnvironment = CreateTestEnvironment())
            {
-                await testEnvironment.StartServer();
-
                // Use a long connection check interval to verify that the subscriptions
                // do not depend on the connection check interval anymore
                var connectionCheckInterval = TimeSpan.FromSeconds(10);
                var receivingClient = await CreateManagedClientAsync(testEnvironment, null, connectionCheckInterval);
                var sendingClient = await testEnvironment.ConnectClient();
+
                await sendingClient.PublishAsync(new MqttApplicationMessage { Topic = "topic", Payload = new byte[] { 1 }, Retain = true });

                var subscribeTime = DateTime.UtcNow;
@@ -344,9 +445,7 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
        {
            using (var testEnvironment = CreateTestEnvironment())
            {
-                await testEnvironment.StartServer();
-
-                var managedClient = testEnvironment.CreateManagedClient();
+                var managedClient = await CreateManagedClientAsync(testEnvironment);

                var sendingClient = await testEnvironment.ConnectClient();

@@ -372,52 +471,14 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
            }
        }

-        [TestMethod]
-        public async Task Will_Message_Send()
-        {
-            using (var testEnvironment = CreateTestEnvironment())
-            {
-                await testEnvironment.StartServer();
-
-                // Prepare the receiving client.
-                var receivedMessagesCount = 0;
-
-                var receivingClient = await testEnvironment.ConnectClient();
-                receivingClient.ApplicationMessageReceivedAsync += e =>
-                {
-                    Interlocked.Increment(ref receivedMessagesCount);
-                    return CompletedTask.Instance;
-                };
-
-                await receivingClient.SubscribeAsync("My/last/will");
-
-                // Prepare the managed client.
-                var clientOptions = new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).WithWillTopic("My/last/will").Build();
-
-                var dyingClient = testEnvironment.CreateClient();
-                var dyingManagedClient = testEnvironment.CreateManagedMqttClient(dyingClient);
-                await dyingManagedClient.StartAsync(new ManagedMqttClientOptionsBuilder().WithClientOptions(clientOptions).Build());
-
-                // Wait until the managed client is fully set up and running.
-                await LongTestDelay();
-
-                // Disposing the client will not sent a DISCONNECT packet so that connection is terminated
-                // which will lead to the will publish.
-                dyingManagedClient.Dispose();
-
-                // Wait for arrival of the will message at the receiver.
-                await LongTestDelay();
-
-                Assert.AreEqual(1, receivedMessagesCount);
-            }
-        }
-
-        static async Task<IManagedMqttClient> CreateManagedClientAsync(
+        async Task<MQTTnet.Extensions.ManagedClient.ManagedMqttClient> CreateManagedClientAsync(
            TestEnvironment testEnvironment,
            IMqttClient underlyingClient = null,
            TimeSpan? connectionCheckInterval = null,
            string host = "localhost")
        {
+            await testEnvironment.StartServer();
+
            var clientOptions = new MqttClientOptionsBuilder().WithTcpServer(host, testEnvironment.ServerPort);

            var managedOptions = new ManagedMqttClientOptionsBuilder().WithClientOptions(clientOptions).Build();
@@ -427,7 +488,7 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
            // at connection check intervals
            managedOptions.ConnectionCheckInterval = connectionCheckInterval ?? TimeSpan.FromSeconds(0.1);

-            var managedClient = testEnvironment.CreateManagedMqttClient(underlyingClient ?? testEnvironment.CreateClient());
+            var managedClient = new MQTTnet.Extensions.ManagedClient.ManagedMqttClient(underlyingClient ?? testEnvironment.CreateClient(), new MqttNetEventLogger());

            var connected = GetConnectedTask(managedClient);

@@ -438,20 +499,35 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient
            return managedClient;
        }

-        static Task GetConnectedTask(IManagedMqttClient managedClient)
+        /// <summary>
+        ///     Returns a task that will finish when the
+        ///     <paramref
+        ///         name="managedClient" />
+        ///     has connected
+        /// </summary>
+        Task GetConnectedTask(MQTTnet.Extensions.ManagedClient.ManagedMqttClient managedClient)
        {
-            var promise = new TaskCompletionSource<bool>();
+            var connected = new TaskCompletionSource<bool>();

            managedClient.ConnectedAsync += e =>
            {
-                promise.TrySetResult(true);
+                connected.TrySetResult(true);
                return CompletedTask.Instance;
            };

-            return promise.Task;
+            return connected.Task;
        }

-        static Task<List<MqttApplicationMessage>> SetupReceivingOfMessages(IManagedMqttClient managedClient, int expectedNumberOfMessages)
+        /// <summary>
+        ///     Returns a task that will return the messages received on
+        ///     <paramref
+        ///         name="managedClient" />
+        ///     when
+        ///     <paramref
+        ///         name="expectedNumberOfMessages" />
+        ///     have been received
+        /// </summary>
+        Task<List<MqttApplicationMessage>> SetupReceivingOfMessages(MQTTnet.Extensions.ManagedClient.ManagedMqttClient managedClient, int expectedNumberOfMessages)
        {
            var receivedMessages = new List<MqttApplicationMessage>();
            var result = new AsyncTaskCompletionSource<List<MqttApplicationMessage>>();
@@ -474,7 +550,7 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient

    public class ManagedMqttClientTestStorage : IManagedMqttClientStorage
    {
-        IList<ManagedMqttApplicationMessage> _messages = new List<ManagedMqttApplicationMessage>();
+        IList<ManagedMqttApplicationMessage> _messages;

        public int GetMessageCount()
        {
@@ -483,6 +559,11 @@ namespace MQTTnet.Tests.Clients.ManagedMqttClient

        public Task<IList<ManagedMqttApplicationMessage>> LoadQueuedMessagesAsync()
        {
+            if (_messages == null)
+            {
+                _messages = new List<ManagedMqttApplicationMessage>();
+            }
+
            return Task.FromResult(_messages);
        }

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.

 using System;
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
@@ -10,6 +11,7 @@ using MQTTnet.Client;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
 using MQTTnet.Internal;
+using MQTTnet.Packets;
 using MQTTnet.Protocol;
 using MQTTnet.Server;

@@ -99,6 +101,8 @@ namespace MQTTnet.Tests.Clients.MqttClient
                // Perform a clean disconnect.
                await client.DisconnectAsync(disconnectOptions);

+                await LongTestDelay();
+
                Assert.IsNotNull(eventArgs);
                Assert.AreEqual(MqttClientDisconnectType.Clean, eventArgs.DisconnectType);
            }
@@ -125,6 +129,8 @@ namespace MQTTnet.Tests.Clients.MqttClient
                // Perform a clean disconnect.
                await client.DisconnectAsync(disconnectOptions);

+                await LongTestDelay();
+
                Assert.IsNotNull(eventArgs);
                Assert.AreEqual(MqttDisconnectReasonCode.MessageRateTooHigh, eventArgs.ReasonCode);
            }
@@ -150,7 +156,9 @@ namespace MQTTnet.Tests.Clients.MqttClient

                // Perform a clean disconnect.
                await client.DisconnectAsync(disconnectOptions);
-                
+
+                await LongTestDelay();
+
                Assert.IsNotNull(eventArgs);
                Assert.IsNotNull(eventArgs.UserProperties);
                Assert.AreEqual(1, eventArgs.UserProperties.Count);
@@ -158,5 +166,35 @@ namespace MQTTnet.Tests.Clients.MqttClient
                Assert.AreEqual("test_value", eventArgs.UserProperties[0].Value);
            }
        }
+
+        [TestMethod]
+        public async Task Return_Non_Success()
+        {
+            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
+            {
+                var server = await testEnvironment.StartServer();
+
+                server.ValidatingConnectionAsync += args =>
+                {
+                    args.ResponseUserProperties = new List<MqttUserProperty>
+                    {
+                        new MqttUserProperty("Property", "Value")
+                    };
+
+                    args.ReasonCode = MqttConnectReasonCode.QuotaExceeded;
+
+                    return CompletedTask.Instance;
+                };
+
+                var client = testEnvironment.CreateClient();
+
+                var response = await client.ConnectAsync(testEnvironment.CreateDefaultClientOptionsBuilder().WithoutThrowOnNonSuccessfulConnectResponse().Build());
+
+                Assert.IsNotNull(response);
+                Assert.AreEqual(MqttClientConnectResultCode.QuotaExceeded, response.ResultCode);
+                Assert.AreEqual(response.UserProperties[0].Name, "Property");
+                Assert.AreEqual(response.UserProperties[0].Value, "Value");
+            }
+        }
    }
 }
@@ -30,7 +30,7 @@ namespace MQTTnet.Tests.Diagnostics

                    var packets = new List<string>();
                    
-                    mqttClient.InspectPackage += eventArgs =>
+                    mqttClient.InspectPacketAsync += eventArgs =>
                    {
                        packets.Add(eventArgs.Direction + ":" + Convert.ToBase64String(eventArgs.Buffer));
                        return CompletedTask.Instance;
@@ -111,7 +111,7 @@ namespace MQTTnet.Tests.Formatter
                PacketIdentifier = 123,
                Dup = true,
                Retain = true,
-                Payload = Encoding.ASCII.GetBytes("HELLO"),
+                PayloadSegment = new ArraySegment<byte>(Encoding.ASCII.GetBytes("HELLO")),
                QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce,
                Topic = "A/B/C"
            };
@@ -318,10 +318,9 @@ namespace MQTTnet.Tests.Formatter
            var publishPacket = new MqttPublishPacket
            {
                Topic = "abcdefghijklmnopqrstuvwxyz0123456789",
-                Payload = payload
+                PayloadSegment = new ArraySegment<byte>(payload)
            };

-
            var serializationHelper = new MqttPacketSerializationHelper();

            var buffer = serializationHelper.Encode(publishPacket);
@@ -329,17 +328,17 @@ namespace MQTTnet.Tests.Formatter

            Assert.IsNotNull(publishPacketCopy);
            Assert.AreEqual(publishPacket.Topic, publishPacketCopy.Topic);
-            CollectionAssert.AreEqual(publishPacket.Payload, publishPacketCopy.Payload);
+            CollectionAssert.AreEqual(publishPacket.PayloadSegment.ToArray(), publishPacketCopy.PayloadSegment.ToArray());

            // Now modify the payload and test again.
-            publishPacket.Payload = Encoding.UTF8.GetBytes("MQTT");
+            publishPacket.PayloadSegment = new ArraySegment<byte>(Encoding.UTF8.GetBytes("MQTT"));

            buffer = serializationHelper.Encode(publishPacket);
            var publishPacketCopy2 = serializationHelper.Decode(buffer) as MqttPublishPacket;

            Assert.IsNotNull(publishPacketCopy2);
            Assert.AreEqual(publishPacket.Topic, publishPacketCopy2.Topic);
-            CollectionAssert.AreEqual(publishPacket.Payload, publishPacketCopy2.Payload);
+            CollectionAssert.AreEqual(publishPacket.PayloadSegment.ToArray(), publishPacketCopy2.PayloadSegment.ToArray());
        }

        [TestMethod]
@@ -463,7 +462,7 @@ namespace MQTTnet.Tests.Formatter
                PacketIdentifier = 123,
                Dup = true,
                Retain = true,
-                Payload = Encoding.ASCII.GetBytes("HELLO"),
+                PayloadSegment = new ArraySegment<byte>(Encoding.ASCII.GetBytes("HELLO")),
                QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce,
                Topic = "A/B/C"
            };
@@ -567,7 +566,6 @@ namespace MQTTnet.Tests.Formatter
                    using (var adapter = new MqttChannelAdapter(
                               channel,
                               new MqttPacketFormatterAdapter(protocolVersion, new MqttBufferWriter(4096, 65535)),
-                               null,
                               new MqttNetEventLogger()))
                    {
                        var receivedPacket = adapter.ReceivePacketAsync(CancellationToken.None).GetAwaiter().GetResult();
@@ -583,19 +581,12 @@ namespace MQTTnet.Tests.Formatter
        MqttProtocolVersion DeserializeAndDetectVersion(MqttPacketFormatterAdapter packetFormatterAdapter, byte[] buffer)
        {
            var channel = new MemoryMqttChannel(buffer);
-            var adapter = new MqttChannelAdapter(channel, packetFormatterAdapter, null, new MqttNetEventLogger());
+            var adapter = new MqttChannelAdapter(channel, packetFormatterAdapter, new MqttNetEventLogger());

            adapter.ReceivePacketAsync(CancellationToken.None).GetAwaiter().GetResult();
            return packetFormatterAdapter.ProtocolVersion;
        }

-        MqttBufferReader ReaderFactory(byte[] data)
-        {
-            var reader = new MqttBufferReader();
-            reader.SetBuffer(data, 0, data.Length);
-            return reader;
-        }
-
        TPacket Roundtrip<TPacket>(TPacket packet, MqttProtocolVersion protocolVersion = MqttProtocolVersion.V311, MqttBufferWriter bufferWriter = null) where TPacket : MqttPacket
        {
            var writer = bufferWriter ?? WriterFactory();
@@ -604,7 +595,7 @@ namespace MQTTnet.Tests.Formatter

            using (var channel = new MemoryMqttChannel(buffer.Join().ToArray()))
            {
-                var adapter = new MqttChannelAdapter(channel, new MqttPacketFormatterAdapter(protocolVersion, new MqttBufferWriter(4096, 65535)), null, new MqttNetEventLogger());
+                var adapter = new MqttChannelAdapter(channel, new MqttPacketFormatterAdapter(protocolVersion, new MqttBufferWriter(4096, 65535)), new MqttNetEventLogger());
                return (TPacket)adapter.ReceivePacketAsync(CancellationToken.None).GetAwaiter().GetResult();
            }
        }
@@ -2,7 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.

+using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Exceptions;
@@ -76,7 +78,7 @@ namespace MQTTnet.Tests.Formatter
            Assert.IsNull(deserialized.UserProperties); // Not supported in v3.1.1
        }
        
-                [TestMethod]
+        [TestMethod]
        public void Serialize_Full_MqttConnAckPacket_V310()
        {
            var connAckPacket = new MqttConnAckPacket
@@ -296,7 +298,7 @@ namespace MQTTnet.Tests.Formatter
                PacketIdentifier = 123,
                Dup = true,
                Retain = true,
-                Payload = Encoding.ASCII.GetBytes("Payload"),
+                PayloadSegment = new ArraySegment<byte>(Encoding.ASCII.GetBytes("Payload")),
                QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce,
                Topic = "Topic",
                ResponseTopic = "/Response",
@@ -320,7 +322,7 @@ namespace MQTTnet.Tests.Formatter
            Assert.AreEqual(publishPacket.PacketIdentifier, deserialized.PacketIdentifier);
            Assert.AreEqual(publishPacket.Dup, deserialized.Dup);
            Assert.AreEqual(publishPacket.Retain, deserialized.Retain);
-            CollectionAssert.AreEqual(publishPacket.Payload, deserialized.Payload);
+            CollectionAssert.AreEqual(publishPacket.PayloadSegment.ToArray(), deserialized.PayloadSegment.ToArray());
            Assert.AreEqual(publishPacket.QualityOfServiceLevel, deserialized.QualityOfServiceLevel);
            Assert.AreEqual(publishPacket.Topic, deserialized.Topic);
            Assert.AreEqual(null, deserialized.ResponseTopic); // Not supported in v3.1.1.
@@ -2,7 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.

+using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Formatter;
@@ -257,7 +259,7 @@ namespace MQTTnet.Tests.Formatter
                PacketIdentifier = 123,
                Dup = true,
                Retain = true,
-                Payload = Encoding.ASCII.GetBytes("Payload"),
+                PayloadSegment = new ArraySegment<byte>(Encoding.ASCII.GetBytes("Payload")),
                QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce,
                Topic = "Topic",
                ResponseTopic = "/Response",
@@ -281,7 +283,7 @@ namespace MQTTnet.Tests.Formatter
            Assert.AreEqual(publishPacket.PacketIdentifier, deserialized.PacketIdentifier);
            Assert.AreEqual(publishPacket.Dup, deserialized.Dup);
            Assert.AreEqual(publishPacket.Retain, deserialized.Retain);
-            CollectionAssert.AreEqual(publishPacket.Payload, deserialized.Payload);
+            CollectionAssert.AreEqual(publishPacket.PayloadSegment.ToArray(), deserialized.PayloadSegment.ToArray());
            Assert.AreEqual(publishPacket.QualityOfServiceLevel, deserialized.QualityOfServiceLevel);
            Assert.AreEqual(publishPacket.Topic, deserialized.Topic);
            Assert.AreEqual(publishPacket.ResponseTopic, deserialized.ResponseTopic);
@@ -1,6 +1,7 @@
 using System;
 using System.Linq;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Exceptions;
 using MQTTnet.Formatter;

 namespace MQTTnet.Tests.Formatter
@@ -47,23 +48,32 @@ namespace MQTTnet.Tests.Formatter
            Assert.AreEqual(1234U, reader.ReadVariableByteInteger());
            Assert.AreEqual(9876U, reader.ReadVariableByteInteger());
        }
+        
+        [TestMethod]
+        [ExpectedException(typeof(MqttProtocolViolationException))]
+        public void Throw_If_String_Too_Long()
+        {
+            var writer = new MqttBufferWriter(4096, 65535);
+            
+            writer.WriteString(string.Empty.PadLeft(65536));
+        }

        [TestMethod]
        public void Write_And_Read_Multiple_Times()
        {
            var writer = new MqttBufferWriter(4096, 65535);
            writer.WriteString("A relative short string.");
-            writer.WriteBinaryData(new byte[1234]);
+            writer.WriteBinary(new byte[1234]);
            writer.WriteByte(0x01);
            writer.WriteByte(0x02);
            writer.WriteVariableByteInteger(5647382);
            writer.WriteString("A relative short string.");
            writer.WriteVariableByteInteger(8574489);
-            writer.WriteBinaryData(new byte[48]);
+            writer.WriteBinary(new byte[48]);
            writer.WriteByte(2);
            writer.WriteByte(0x02);
            writer.WriteString("fjgffiogfhgfhoihgoireghreghreguhreguireoghreouighreouighreughreguiorehreuiohruiorehreuioghreug");
-            writer.WriteBinaryData(new byte[3]);
+            writer.WriteBinary(new byte[3]);

            var readPayload = new ArraySegment<byte>(writer.GetBuffer(), 0, writer.Length).ToArray();

@@ -51,10 +51,7 @@ namespace MQTTnet.Tests.Mockups

        public void AssertReceivedCountEquals(int expectedCount)
        {
-            lock (_receivedEventArgs)
-            {
-                Assert.AreEqual(expectedCount, _receivedEventArgs.Count);
-            }
+            Assert.AreEqual(expectedCount, Count);
        }

        public string GeneratePayloadSequence()
@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.

-#region
-
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -21,8 +19,6 @@ using MQTTnet.LowLevelClient;
 using MQTTnet.Protocol;
 using MQTTnet.Server;

-#endregion
-
 namespace MQTTnet.Tests.Mockups
 {
    public sealed class TestEnvironment : IDisposable
@@ -32,7 +28,6 @@ namespace MQTTnet.Tests.Mockups

        readonly List<Exception> _exceptions = new List<Exception>();
        readonly List<ILowLevelMqttClient> _lowLevelClients = new List<ILowLevelMqttClient>();
-        readonly List<IManagedMqttClient> _managedClients = new List<IManagedMqttClient>();
        readonly MqttProtocolVersion _protocolVersion;
        readonly List<string> _serverErrors = new List<string>();

@@ -94,12 +89,8 @@ namespace MQTTnet.Tests.Mockups

        public int ServerPort { get; set; }

-        public List<MqttApplicationMessage> ServerReceivedApplicationMessages { get; } = new List<MqttApplicationMessage>();
-
        public TestContext TestContext { get; }

-        public bool TrackServerReceivedApplicationMessages { get; set; }
-
        public Task<IMqttClient> ConnectClient()
        {
            return ConnectClient(Factory.CreateClientOptionsBuilder().WithProtocolVersion(_protocolVersion));
@@ -247,11 +238,6 @@ namespace MQTTnet.Tests.Mockups
            }
        }

-        public ManagedMqttClientOptions CreateDefaultManagedMqttClientOptions()
-        {
-            return Factory.CreateManagedMqttClientOptionsBuilder().WithClientOptions(Factory.CreateClientOptionsBuilder().WithTcpServer("127.0.0.1", ServerPort).Build()).Build();
-        }
-
        public MqttClientOptions CreateDefaultClientOptions()
        {
            return CreateDefaultClientOptionsBuilder().Build();
@@ -259,7 +245,7 @@ namespace MQTTnet.Tests.Mockups

        public MqttClientOptionsBuilder CreateDefaultClientOptionsBuilder()
        {
-            return Factory.CreateClientOptionsBuilder().WithProtocolVersion(_protocolVersion).WithTcpServer("127.0.0.1", ServerPort);
+            return Factory.CreateClientOptionsBuilder().WithProtocolVersion(_protocolVersion).WithTcpServer("127.0.0.1", ServerPort).WithClientId(TestContext.TestName + "_" + Guid.NewGuid());
        }

        public ILowLevelMqttClient CreateLowLevelClient()
@@ -273,21 +259,6 @@ namespace MQTTnet.Tests.Mockups
            }
        }

-        public IManagedMqttClient CreateManagedClient()
-        {
-            return Factory.CreateManagedMqttClient(CreateClient());
-        }
-
-        public IManagedMqttClient CreateManagedMqttClient()
-        {
-            return Factory.CreateManagedMqttClient(CreateClient(), ClientLogger);
-        }
-
-        public IManagedMqttClient CreateManagedMqttClient(IMqttClient client)
-        {
-            return Factory.CreateManagedMqttClient(client, ClientLogger);
-        }
-
        public MqttServer CreateServer(MqttServerOptions options)
        {
            if (Server != null)
@@ -299,11 +270,6 @@ namespace MQTTnet.Tests.Mockups

            Server = Factory.CreateMqttServer(options, logger);

-            if (TrackServerReceivedApplicationMessages)
-            {
-                Server.InterceptingPublishAsync += ServerOnInterceptingPublishAsync;
-            }
-
            Server.ValidatingConnectionAsync += e =>
            {
                if (TestContext != null)
@@ -340,18 +306,6 @@ namespace MQTTnet.Tests.Mockups
                }
            }

-            foreach (var managedMqttClient in _managedClients)
-            {
-                try
-                {
-                    managedMqttClient.StopAsync().Wait();
-                }
-                finally
-                {
-                    managedMqttClient.Dispose();
-                }
-            }
-
            foreach (var lowLevelMqttClient in _lowLevelClients)
            {
                lowLevelMqttClient.Dispose();
@@ -378,13 +332,6 @@ namespace MQTTnet.Tests.Mockups
            }
        }

-        public async Task<IManagedMqttClient> StartManagedClient()
-        {
-            var managedClient = Factory.CreateManagedMqttClient(CreateClient());
-            await managedClient.StartAsync(CreateDefaultManagedMqttClientOptions());
-            return managedClient;
-        }
-
        public Task<MqttServer> StartServer()
        {
            return StartServer(Factory.CreateServerOptionsBuilder());
@@ -454,15 +401,5 @@ namespace MQTTnet.Tests.Mockups
                _exceptions.Add(exception);
            }
        }
-
-        Task ServerOnInterceptingPublishAsync(InterceptingPublishEventArgs arg)
-        {
-            lock (ServerReceivedApplicationMessages)
-            {
-                ServerReceivedApplicationMessages.Add(arg.ApplicationMessage);
-            }
-
-            return CompletedTask.Instance;
-        }
    }
 }
@@ -0,0 +1,48 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Tests
+{
+    [TestClass]
+    public class MqttApplicationMessageTest
+    {
+        [TestMethod]
+        public void PayloadSegment()
+        {
+            var message = new MqttApplicationMessage();
+            Assert.AreEqual(0, message.Payload.Length);
+            Assert.AreEqual(0, message.PayloadSegment.Count);
+
+            Assert.IsTrue(object.ReferenceEquals(message.Payload, message.Payload));
+            Assert.IsTrue(object.ReferenceEquals(message.Payload, message.PayloadSegment.Array));
+
+            message.Payload = new byte[] { 1, 2 };
+            Assert.AreEqual(2, message.Payload.Length);
+            Assert.AreEqual(2, message.PayloadSegment.Count);
+            Assert.IsTrue(object.ReferenceEquals(message.Payload, message.Payload));
+            Assert.IsTrue(object.ReferenceEquals(message.Payload, message.PayloadSegment.Array));
+
+            message.Payload = new byte[] { 1, 2, 3 };
+            Assert.AreEqual(3, message.Payload.Length);
+            Assert.AreEqual(3, message.PayloadSegment.Count);
+            Assert.IsTrue(object.ReferenceEquals(message.Payload, message.Payload));
+            Assert.IsTrue(object.ReferenceEquals(message.Payload, message.PayloadSegment.Array));
+
+            message.PayloadSegment = new ArraySegment<byte>(new byte[] { 1, 2, 3 });
+            Assert.AreEqual(3, message.Payload.Length);
+            Assert.AreEqual(3, message.PayloadSegment.Count);
+            Assert.IsTrue(object.ReferenceEquals(message.Payload, message.Payload));
+            Assert.IsTrue(object.ReferenceEquals(message.Payload, message.PayloadSegment.Array));
+
+            message.PayloadSegment = new ArraySegment<byte>(new byte[] { 1, 2, 3 }, 1, 1);
+            Assert.AreEqual(1, message.Payload.Length);
+            Assert.AreEqual(1, message.PayloadSegment.Count);
+            Assert.IsTrue(object.ReferenceEquals(message.Payload, message.Payload));
+            Assert.IsFalse(object.ReferenceEquals(message.Payload, message.PayloadSegment.Array));
+        }
+    }
+}
@@ -31,7 +31,7 @@ namespace MQTTnet.Tests
            {
                var formatterAdapter = new MqttPacketFormatterAdapter(_protocolVersion, new MqttBufferWriter(4096, 65535));

-                var adapter = new MqttChannelAdapter(channel, formatterAdapter, null, MqttNetNullLogger.Instance);
+                var adapter = new MqttChannelAdapter(channel, formatterAdapter, MqttNetNullLogger.Instance);
                return adapter.ReceivePacketAsync(CancellationToken.None).GetAwaiter().GetResult();
            }
        }
@@ -24,10 +24,10 @@ namespace MQTTnet.Tests
            writer.WriteString("1234567890");
            Assert.AreEqual(10 + 2, writer.Length);

-            writer.WriteBinaryData(new byte[300]);
+            writer.WriteBinary(new byte[300]);
            Assert.AreEqual(300 + 2 + 12, writer.Length);

-            writer.WriteBinaryData(new byte[5000]);
+            writer.WriteBinary(new byte[5000]);
            Assert.AreEqual(5000 + 2 + 300 + 2 + 12, writer.Length);
        }
    }
@@ -954,7 +954,7 @@ namespace MQTTnet.Tests.Server

                var client = testEnvironment.CreateClient();

-                client.InspectPackage += e =>
+                client.InspectPacketAsync += e =>
                {
                    if (e.Buffer.Length > 0)
                    {
@@ -228,7 +228,7 @@ namespace MQTTnet.Tests.Server

        CheckSubscriptionsResult CheckSubscriptions(string topic, MqttQualityOfServiceLevel applicationMessageQoSLevel, string senderClientId)
        {
-            MqttSubscription.CalculateTopicHash(topic, out var topicHash, out _, out _);
+            MqttTopicHash.Calculate(topic, out var topicHash, out _, out _);
            return _subscriptionsManager.CheckSubscriptions(topic, topicHash, applicationMessageQoSLevel, senderClientId);
        }
    }
@@ -1,58 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System.Threading.Tasks;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Client;
-using MQTTnet.Formatter;
-using MQTTnet.Protocol;
-
-namespace MQTTnet.Tests.Server
-{
-    [TestClass]
-    public sealed class Publish_Tests : BaseTestClass
-    {
-        [TestMethod]
-        public async Task Return_Success_When_Subscribed()
-        {
-            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
-            {
-                await testEnvironment.StartServer();
-
-                var sender = await testEnvironment.ConnectClient();
-                var receiver = await testEnvironment.ConnectClient();
-
-                await receiver.SubscribeAsync("A");
-
-                // AtLeastOnce is required to get an ACK packet from the server.
-                var publishResult = await sender.PublishStringAsync("A", "Payload", MqttQualityOfServiceLevel.AtLeastOnce);
-                
-                Assert.AreEqual(MqttClientPublishReasonCode.Success, publishResult.ReasonCode);
-                
-                Assert.AreEqual(true, publishResult.IsSuccess);
-            }
-        }
-        
-        [TestMethod]
-        public async Task Return_NoMatchingSubscribers_When_Not_Subscribed()
-        {
-            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
-            {
-                await testEnvironment.StartServer();
-
-                var sender = await testEnvironment.ConnectClient();
-                var receiver = await testEnvironment.ConnectClient();
-             
-                await receiver.SubscribeAsync("A");
-
-                // AtLeastOnce is required to get an ACK packet from the server.
-                var publishResult = await sender.PublishStringAsync("B", "Payload", MqttQualityOfServiceLevel.AtLeastOnce);
-                
-                Assert.AreEqual(MqttClientPublishReasonCode.NoMatchingSubscribers, publishResult.ReasonCode);
-                
-                Assert.AreEqual(true, publishResult.IsSuccess);
-            }
-        }
-    }
-}
@@ -5,6 +5,8 @@
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
+using MQTTnet.Formatter;
+using MQTTnet.Internal;
 using MQTTnet.Protocol;

 namespace MQTTnet.Tests.Server
@@ -27,5 +29,118 @@ namespace MQTTnet.Tests.Server
                await client.PublishStringAsync("test", qualityOfServiceLevel: MqttQualityOfServiceLevel.AtLeastOnce);
            }
        }
+
+        [TestMethod]
+        public async Task Return_NoMatchingSubscribers_When_Not_Subscribed()
+        {
+            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
+            {
+                await testEnvironment.StartServer();
+
+                var sender = await testEnvironment.ConnectClient();
+                var receiver = await testEnvironment.ConnectClient();
+
+                await receiver.SubscribeAsync("A");
+
+                // AtLeastOnce is required to get an ACK packet from the server.
+                var publishResult = await sender.PublishStringAsync("B", "Payload", MqttQualityOfServiceLevel.AtLeastOnce);
+
+                Assert.AreEqual(MqttClientPublishReasonCode.NoMatchingSubscribers, publishResult.ReasonCode);
+
+                Assert.AreEqual(true, publishResult.IsSuccess);
+            }
+        }
+
+        [TestMethod]
+        public async Task Return_Success_When_Subscribed()
+        {
+            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
+            {
+                await testEnvironment.StartServer();
+
+                var sender = await testEnvironment.ConnectClient();
+                var receiver = await testEnvironment.ConnectClient();
+
+                await receiver.SubscribeAsync("A");
+
+                // AtLeastOnce is required to get an ACK packet from the server.
+                var publishResult = await sender.PublishStringAsync("A", "Payload", MqttQualityOfServiceLevel.AtLeastOnce);
+
+                Assert.AreEqual(MqttClientPublishReasonCode.Success, publishResult.ReasonCode);
+
+                Assert.AreEqual(true, publishResult.IsSuccess);
+            }
+        }
+
+        [TestMethod]
+        public async Task Intercept_Client_Enqueue()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                var server = await testEnvironment.StartServer();
+                
+                var sender = await testEnvironment.ConnectClient();
+                
+                var receiver = await testEnvironment.ConnectClient();
+                await receiver.SubscribeAsync("A");
+                var receivedMessages = testEnvironment.CreateApplicationMessageHandler(receiver);
+                
+                await sender.PublishStringAsync("A", "Payload", MqttQualityOfServiceLevel.AtLeastOnce);
+
+                await LongTestDelay();
+                
+                receivedMessages.AssertReceivedCountEquals(1);
+                
+                server.InterceptingClientEnqueueAsync += e =>
+                {
+                    e.AcceptEnqueue = false;
+                    return CompletedTask.Instance;
+                };
+                
+                await sender.PublishStringAsync("A", "Payload", MqttQualityOfServiceLevel.AtLeastOnce);
+
+                await LongTestDelay();
+                
+                // Do not increase because the internal enqueue to the target client is not accepted!
+                receivedMessages.AssertReceivedCountEquals(1);
+            }
+        }
+
+        [TestMethod]
+        public async Task Intercept_Client_Enqueue_Multiple_Clients_Subscribed_Messages_Are_Filtered()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                var server = await testEnvironment.StartServer();
+
+                var sender = await testEnvironment.ConnectClient();
+
+                var receiverOne = await testEnvironment.ConnectClient(o => o.WithClientId("One"));
+                await receiverOne.SubscribeAsync("A");
+                var receivedMessagesOne = testEnvironment.CreateApplicationMessageHandler(receiverOne);
+
+                var receiverTwo = await testEnvironment.ConnectClient(o => o.WithClientId("Two"));
+                await receiverTwo.SubscribeAsync("A");
+                var receivedMessagesTwo = testEnvironment.CreateApplicationMessageHandler(receiverTwo);
+
+                var receiverThree = await testEnvironment.ConnectClient(o => o.WithClientId("Three"));
+                await receiverThree.SubscribeAsync("A");
+                var receivedMessagesThree = testEnvironment.CreateApplicationMessageHandler(receiverThree);
+
+                server.InterceptingClientEnqueueAsync += e =>
+                {
+                    if (e.ReceiverClientId.Contains("Two")) e.AcceptEnqueue = false;
+                    return CompletedTask.Instance;
+                };
+
+                await sender.PublishStringAsync("A", "Payload", MqttQualityOfServiceLevel.AtLeastOnce);
+
+                await LongTestDelay();
+
+                receivedMessagesOne.AssertReceivedCountEquals(1);
+                receivedMessagesTwo.AssertReceivedCountEquals(0);
+                receivedMessagesThree.AssertReceivedCountEquals(1);
+            }
+        }
    }
 }
@@ -164,7 +164,7 @@ namespace MQTTnet.Tests.Server

                var clientOptions = new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1", testEnvironment.ServerPort).WithCredentials(userName, password).Build();

-                var ex = await Assert.ThrowsExceptionAsync<MqttConnectingFailedException>(async () => await client.ConnectAsync(clientOptions));
+                var ex = await Assert.ThrowsExceptionAsync<MqttConnectingFailedException>(() => client.ConnectAsync(clientOptions));
                Assert.AreEqual(MqttClientConnectResultCode.BadUserNameOrPassword, ex.Result.ResultCode);
            }
        }
@@ -62,7 +62,7 @@ namespace MQTTnet.Tests.Server
                }
            }
        }
-        
+
        [TestMethod]
        public async Task Deny_Invalid_Topic()
        {
@@ -90,6 +90,29 @@ namespace MQTTnet.Tests.Server
            }
        }

+        [TestMethod]
+        public async Task Intercept_Subscribe_With_User_Properties()
+        {
+            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
+            {
+                var server = await testEnvironment.StartServer();
+
+                InterceptingSubscriptionEventArgs eventArgs = null;
+                server.InterceptingSubscriptionAsync += e =>
+                {
+                    eventArgs = e;
+                    return CompletedTask.Instance;
+                };
+
+                var client = await testEnvironment.ConnectClient();
+
+                var subscribeOptions = testEnvironment.Factory.CreateSubscribeOptionsBuilder().WithTopicFilter("X").WithUserProperty("A", "1").Build();
+                await client.SubscribeAsync(subscribeOptions);
+
+                CollectionAssert.AreEqual(subscribeOptions.UserProperties.ToList(), eventArgs.UserProperties);
+            }
+        }
+
        [TestMethod]
        [ExpectedException(typeof(MqttClientDisconnectedException))]
        public async Task Disconnect_While_Subscribing()
@@ -105,7 +128,7 @@ namespace MQTTnet.Tests.Server
                await client.SubscribeAsync("#");
            }
        }
-        
+
        [TestMethod]
        public async Task Enqueue_Message_After_Subscription()
        {
@@ -47,7 +47,7 @@ namespace MQTTnet.Tests.Server
                var topics = t.Value;
                foreach (var topic in topics)
                {
-                    MqttSubscription.CalculateTopicHash(topic, out var topicHash, out var hashMask, out var hasWildcard);
+                    MqttTopicHash.Calculate(topic, out var topicHash, out var hashMask, out var hasWildcard);

                    bucketDepths.TryGetValue(topicHash, out var currentValue);
                    ++currentValue;
@@ -96,7 +96,7 @@ namespace MQTTnet.Tests.Server
        {
            var topic = "asdfasdf/asdfasdf/asdfasdf/asdfasdf/asdfas/dfaf/assfdgsdfgdf/#";

-            MqttSubscription.CalculateTopicHash(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);
+            MqttTopicHash.Calculate(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);

            Assert.IsTrue(topicHasWildcard, "Wildcard not detected");
        }
@@ -110,7 +110,7 @@ namespace MQTTnet.Tests.Server
        {
            var topic = "asdfasdf/asdfasdf/asdfasdf/asdfasdf/asdfas/dfaf/assfdgsdfgdf/+";

-            MqttSubscription.CalculateTopicHash(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);
+            MqttTopicHash.Calculate(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);

            Assert.IsTrue(topicHasWildcard, "Wildcard not detected");
        }
@@ -150,7 +150,7 @@ namespace MQTTnet.Tests.Server

            // UInt64 is limited to 8 levels

-            MqttSubscription.CalculateTopicHash(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);
+            MqttTopicHash.Calculate(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);

            Assert.IsTrue(topicHasWildcard, "Wildcard not detected");

@@ -212,7 +212,7 @@ namespace MQTTnet.Tests.Server

            var topic = sb.ToString();

-            MqttSubscription.CalculateTopicHash(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);
+            MqttTopicHash.Calculate(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);

            Assert.IsFalse(topicHasWildcard, "Wildcard detected when not present");

@@ -269,7 +269,7 @@ namespace MQTTnet.Tests.Server

            var topic = sb.ToString();

-            MqttSubscription.CalculateTopicHash(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);
+            MqttTopicHash.Calculate(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);

            Assert.IsTrue(topicHasWildcard, "Wildcard not detected");

@@ -319,7 +319,7 @@ namespace MQTTnet.Tests.Server
            var l3 = "#";
            var topic = $"{l0}/{l1}/{l2}/{l3}";

-            MqttSubscription.CalculateTopicHash(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);
+            MqttTopicHash.Calculate(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);

            Assert.IsTrue(topicHasWildcard, "Wildcard not detected");

@@ -354,7 +354,7 @@ namespace MQTTnet.Tests.Server
            var l3 = "prop1";
            var topic = $"{l0}/{l1}/{l2}/{l3}";

-            MqttSubscription.CalculateTopicHash(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);
+            MqttTopicHash.Calculate(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);

            Assert.IsFalse(topicHasWildcard, "Wildcard detected when not wildcard present");

@@ -447,7 +447,7 @@ namespace MQTTnet.Tests.Server
            var l3 = "prop1";
            var topic = $"{l0}/{l1}/{l2}/{l3}";

-            MqttSubscription.CalculateTopicHash(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);
+            MqttTopicHash.Calculate(topic, out var topicHash, out var topicHashMask, out var topicHasWildcard);

            Assert.IsTrue(topicHasWildcard, "Wildcard not detected");

@@ -475,7 +475,7 @@ namespace MQTTnet.Tests.Server

        void CheckTopicHash(string topic, ulong expectedHash, ulong expectedHashMask)
        {
-            MqttSubscription.CalculateTopicHash(topic, out var topicHash, out var hashMask, out var hasWildcard);
+            MqttTopicHash.Calculate(topic, out var topicHash, out var hashMask, out var hasWildcard);

            Console.WriteLine();
            Console.WriteLine("Topic: " + topic);
@@ -501,7 +501,7 @@ namespace MQTTnet.Tests.Server
                {
                    var topicToFind = topicsToFind[countDown];

-                    MqttSubscription.CalculateTopicHash(topicToFind, out var topicHash, out _, out _);
+                    MqttTopicHash.Calculate(topicToFind, out var topicHash, out _, out _);

                    clientSession.TryCheckSubscriptions(topicToFind, topicHash, MqttQualityOfServiceLevel.AtMostOnce, "OtherClient", out var result);
                    if (result.IsSubscribed)
@@ -0,0 +1,204 @@
+#if !WINDOWS_UWP && (NET48_OR_GREATER || NET5_0_OR_GREATER)
+using System;
+using System.Linq;
+using System.Net;
+using System.Security.Authentication;
+using System.Security.Cryptography;
+using System.Security.Cryptography.X509Certificates;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Certificates;
+using MQTTnet.Client;
+using MQTTnet.Formatter;
+using MQTTnet.Server;
+using MQTTnet.Tests.Mockups;
+
+namespace MQTTnet.Tests.Server
+{
+    [TestClass]
+    public sealed class Tls_Tests : BaseTestClass
+    {
+        static X509Certificate2 CreateCertificate(string oid)
+        {
+            var sanBuilder = new SubjectAlternativeNameBuilder();
+            sanBuilder.AddIpAddress(IPAddress.Loopback);
+            sanBuilder.AddIpAddress(IPAddress.IPv6Loopback);
+            sanBuilder.AddDnsName("localhost");
+            
+            using (var rsa = RSA.Create())
+            {
+                var certRequest = new CertificateRequest("CN=localhost", rsa, HashAlgorithmName.SHA512, RSASignaturePadding.Pkcs1);
+
+                certRequest.CertificateExtensions.Add(
+                    new X509KeyUsageExtension(X509KeyUsageFlags.DataEncipherment | X509KeyUsageFlags.KeyEncipherment | X509KeyUsageFlags.DigitalSignature, false));
+
+                certRequest.CertificateExtensions.Add(new X509EnhancedKeyUsageExtension(new OidCollection { new Oid(oid) }, false));
+
+                certRequest.CertificateExtensions.Add(sanBuilder.Build());
+
+                using (var certificate = certRequest.CreateSelfSigned(DateTimeOffset.Now.AddMinutes(-10), DateTimeOffset.Now.AddMinutes(10)))
+                {
+                    var pfxCertificate = new X509Certificate2(
+                        certificate.Export(X509ContentType.Pfx),
+                        (string)null,
+                        X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.Exportable);
+
+                    return pfxCertificate;
+                }
+            }
+        }
+
+        [TestMethod]
+        public async Task Tls_Swap_Test()
+        {
+            var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500);
+            var serverOptionsBuilder = testEnvironment.Factory.CreateServerOptionsBuilder();
+
+            var firstOid = "1.3.6.1.5.5.7.3.1";
+            var secondOid = "1.3.6.1.5.5.7.3.2";
+
+            var certificateProvider = new CertificateProvider
+            {
+                CurrentCertificate = CreateCertificate(firstOid)
+            };
+
+            serverOptionsBuilder.WithoutDefaultEndpoint().WithEncryptedEndpoint().WithEncryptionSslProtocol(SslProtocols.Tls12).WithEncryptionCertificate(certificateProvider);
+
+            var serverOptions = serverOptionsBuilder.Build();
+
+            var server = testEnvironment.CreateServer(serverOptions);
+
+            var publishedCount = 0;
+            server.InterceptingPublishAsync += args =>
+            {
+                Interlocked.Increment(ref publishedCount);
+
+                return Task.CompletedTask;
+            };
+
+            await server.StartAsync();
+
+            var firstClient = await ConnectClientAsync(
+                testEnvironment,
+                args =>
+                {
+                    Assert.AreEqual(firstOid, ((X509Certificate2)args.Certificate).Extensions.OfType<X509EnhancedKeyUsageExtension>().First().EnhancedKeyUsages[0].Value);
+                    return true;
+                });
+
+            var firstClientReceivedCount = 0;
+            firstClient.ApplicationMessageReceivedAsync += args =>
+            {
+                Interlocked.Increment(ref firstClientReceivedCount);
+
+                return Task.CompletedTask;
+            };
+
+            await firstClient.SubscribeAsync("TestTopic1");
+
+            await firstClient.PublishAsync(
+                new MqttApplicationMessage
+                {
+                    Topic = "TestTopic1",
+                    Payload = new byte[] { 1, 2, 3, 4 }
+                });
+
+            await testEnvironment.Server.InjectApplicationMessage(
+                new InjectedMqttApplicationMessage(
+                    new MqttApplicationMessage
+                    {
+                        Topic = "TestTopic1",
+                        Payload = new byte[] { 1, 2, 3, 4 }
+                    }));
+
+            certificateProvider.CurrentCertificate = CreateCertificate(secondOid);
+
+            // Validate that the certificate was switched
+            var secondClient = await ConnectClientAsync(
+                testEnvironment,
+                args =>
+                {
+                    Assert.AreEqual(secondOid, ((X509Certificate2)args.Certificate).Extensions.OfType<X509EnhancedKeyUsageExtension>().First().EnhancedKeyUsages[0].Value);
+                    return true;
+                });
+
+            var secondClientReceivedCount = 0;
+            secondClient.ApplicationMessageReceivedAsync += args =>
+            {
+                Interlocked.Increment(ref secondClientReceivedCount);
+
+                return Task.CompletedTask;
+            };
+
+            await secondClient.SubscribeAsync("TestTopic2");
+
+            await firstClient.PublishAsync(
+                new MqttApplicationMessage
+                {
+                    Topic = "TestTopic2",
+                    Payload = new byte[] { 1, 2, 3, 4 }
+                });
+
+            await testEnvironment.Server.InjectApplicationMessage(
+                new InjectedMqttApplicationMessage(
+                    new MqttApplicationMessage
+                    {
+                        Topic = "TestTopic2",
+                        Payload = new byte[] { 1, 2, 3, 4 }
+                    }));
+
+            // Ensure first client still works
+            await firstClient.PublishAsync(
+                new MqttApplicationMessage
+                {
+                    Topic = "TestTopic1",
+                    Payload = new byte[] { 1, 2, 3, 4 }
+                });
+
+            await testEnvironment.Server.InjectApplicationMessage(
+                new InjectedMqttApplicationMessage(
+                    new MqttApplicationMessage
+                    {
+                        Topic = "TestTopic1",
+                        Payload = new byte[] { 1, 2, 3, 4 }
+                    }));
+
+            await Task.Delay(1000);
+
+            Assert.AreEqual(6, publishedCount);
+            Assert.AreEqual(4, firstClientReceivedCount);
+            Assert.AreEqual(2, secondClientReceivedCount);
+
+            await server.StopAsync();
+        }
+
+        static async Task<IMqttClient> ConnectClientAsync(TestEnvironment testEnvironment, Func<MqttClientCertificateValidationEventArgs, bool> certValidator)
+        {
+            var clientOptionsBuilder = testEnvironment.Factory.CreateClientOptionsBuilder();
+            clientOptionsBuilder.WithClientId(Guid.NewGuid().ToString())
+                .WithTcpServer("localhost", 8883)
+                .WithTls(
+                    tls =>
+                    {
+                        tls.UseTls = true;
+                        tls.SslProtocol = SslProtocols.Tls12;
+                        tls.CertificateValidationHandler = certValidator;
+                    });
+
+            var clientOptions = clientOptionsBuilder.Build();
+            return await testEnvironment.ConnectClient(clientOptions);
+        }
+        
+        sealed class CertificateProvider : ICertificateProvider
+        {
+            public X509Certificate2 CurrentCertificate { get; set; }
+
+            public X509Certificate2 GetCertificate()
+            {
+                return CurrentCertificate;
+            }
+        }
+    }
+}
+#endif
@@ -2,10 +2,14 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.

+using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
+using MQTTnet.Formatter;
+using MQTTnet.Internal;
 using MQTTnet.Protocol;
+using MQTTnet.Server;

 namespace MQTTnet.Tests.Server
 {
@@ -28,5 +32,28 @@ namespace MQTTnet.Tests.Server
                await client.UnsubscribeAsync("#");
            }
        }
+
+        [TestMethod]
+        public async Task Intercept_Unsubscribe_With_User_Properties()
+        {
+            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
+            {
+                var server = await testEnvironment.StartServer();
+
+                InterceptingUnsubscriptionEventArgs eventArgs = null;
+                server.InterceptingUnsubscriptionAsync += e =>
+                {
+                    eventArgs = e;
+                    return CompletedTask.Instance;
+                };
+
+                var client = await testEnvironment.ConnectClient();
+
+                var unsubscribeOptions = testEnvironment.Factory.CreateUnsubscribeOptionsBuilder().WithTopicFilter("X").WithUserProperty("A", "1").Build();
+                await client.UnsubscribeAsync(unsubscribeOptions);
+
+                CollectionAssert.AreEqual(unsubscribeOptions.UserProperties.ToList(), eventArgs.UserProperties);
+            }
+        }
    }
 }
@@ -150,18 +150,8 @@ namespace MQTTnet.Tests
        {
            Assert.AreEqual(expectedResult, MqttTopicFilterComparer.Compare(topic, filter));

-            ulong topicHash;
-            ulong topicHashMask;
-            bool topicHasWildcard;
-
-            MqttSubscription.CalculateTopicHash(topic, out topicHash, out topicHashMask, out topicHasWildcard);
-
-
-            ulong filterTopicHash;
-            ulong filterTopicHashMask;
-            bool filterTopicHasWildcard;
-
-            MqttSubscription.CalculateTopicHash(filter, out filterTopicHash, out filterTopicHashMask, out filterTopicHasWildcard);
+            MqttTopicHash.Calculate(topic, out var topicHash, out _, out _);
+            MqttTopicHash.Calculate(filter, out var filterTopicHash, out var filterTopicHashMask, out _);

            if (expectedResult == MqttTopicFilterCompareResult.IsMatch)
            {
@@ -27,18 +27,15 @@ namespace MQTTnet.Adapter
        readonly byte[] _fixedHeaderBuffer = new byte[2];
        readonly MqttNetSourceLogger _logger;

-        readonly MqttPacketInspector _packetInspector;
-
        readonly byte[] _singleByteBuffer = new byte[1];

        readonly AsyncLock _syncRoot = new AsyncLock();

-        Statistics _statistics;     // mutable struct, don't make readonly!
+        Statistics _statistics; // mutable struct, don't make readonly!

-        public MqttChannelAdapter(IMqttChannel channel, MqttPacketFormatterAdapter packetFormatterAdapter, MqttPacketInspector packetInspector, IMqttNetLogger logger)
+        public MqttChannelAdapter(IMqttChannel channel, MqttPacketFormatterAdapter packetFormatterAdapter, IMqttNetLogger logger)
        {
            _channel = channel ?? throw new ArgumentNullException(nameof(channel));
-            _packetInspector = packetInspector;

            PacketFormatterAdapter = packetFormatterAdapter ?? throw new ArgumentNullException(nameof(packetFormatterAdapter));

@@ -64,6 +61,10 @@ namespace MQTTnet.Adapter

        public MqttPacketFormatterAdapter PacketFormatterAdapter { get; }

+        public MqttPacketInspector PacketInspector { get; set; }
+
+        public bool AllowPacketFragmentation { get; set; } = true;
+
        public async Task ConnectAsync(CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
@@ -126,7 +127,7 @@ namespace MQTTnet.Adapter

            try
            {
-                _packetInspector?.BeginReceivePacket();
+                PacketInspector?.BeginReceivePacket();

                ReceivedMqttPacket receivedPacket;
                var receivedPacketTask = ReceiveAsync(cancellationToken);
@@ -144,7 +145,7 @@ namespace MQTTnet.Adapter
                    return null;
                }

-                _packetInspector?.EndReceivePacket();
+                PacketInspector?.EndReceivePacket();

                Interlocked.Add(ref _statistics._bytesSent, receivedPacket.TotalLength);

@@ -180,7 +181,10 @@ namespace MQTTnet.Adapter
            return null;
        }

-        public void ResetStatistics() => _statistics.Reset();
+        public void ResetStatistics()
+        {
+            _statistics.Reset();
+        }

        public async Task SendPacketAsync(MqttPacket packet, CancellationToken cancellationToken)
        {
@@ -197,18 +201,18 @@ namespace MQTTnet.Adapter
                try
                {
                    var packetBuffer = PacketFormatterAdapter.Encode(packet);
-                    _packetInspector?.BeginSendPacket(packetBuffer);
+                    PacketInspector?.BeginSendPacket(packetBuffer);

                    _logger.Verbose("TX ({0} bytes) >>> {1}", packetBuffer.Length, packet);
-
-                    if (packetBuffer.Payload.Count > 0)
+                    
+                    if (packetBuffer.Payload.Count == 0 || !AllowPacketFragmentation)
                    {
-                        await _channel.WriteAsync(packetBuffer.Packet, false, cancellationToken).ConfigureAwait(false);
-                        await _channel.WriteAsync(packetBuffer.Payload, true, cancellationToken).ConfigureAwait(false);
+                        await _channel.WriteAsync(packetBuffer.Join(), true, cancellationToken).ConfigureAwait(false);
                    }
                    else
                    {
-                        await _channel.WriteAsync(packetBuffer.Packet, true, cancellationToken).ConfigureAwait(false);
+                        await _channel.WriteAsync(packetBuffer.Packet, false, cancellationToken).ConfigureAwait(false);
+                        await _channel.WriteAsync(packetBuffer.Payload, true, cancellationToken).ConfigureAwait(false);
                    }

                    Interlocked.Add(ref _statistics._bytesReceived, packetBuffer.Length);
@@ -270,7 +274,7 @@ namespace MQTTnet.Adapter
                    return 0;
                }

-                _packetInspector?.FillReceiveBuffer(_singleByteBuffer);
+                PacketInspector?.FillReceiveBuffer(_singleByteBuffer);

                encodedByte = _singleByteBuffer[0];

@@ -309,7 +313,7 @@ namespace MQTTnet.Adapter
                {
                    return ReadFixedHeaderResult.ConnectionClosed;
                }
-               
+
                if (cancellationToken.IsCancellationRequested)
                {
                    return ReadFixedHeaderResult.Canceled;
@@ -323,7 +327,7 @@ namespace MQTTnet.Adapter
                totalBytesRead += bytesRead;
            }

-            _packetInspector?.FillReceiveBuffer(buffer);
+            PacketInspector?.FillReceiveBuffer(buffer);

            var hasRemainingLength = buffer[1] != 0;
            if (!hasRemainingLength)
@@ -407,7 +411,7 @@ namespace MQTTnet.Adapter
                    bodyOffset += readBytes;
                } while (bodyOffset < bodyLength);

-                _packetInspector?.FillReceiveBuffer(body);
+                PacketInspector?.FillReceiveBuffer(body);

                var bodySegment = new ArraySegment<byte>(body, 0, bodyLength);
                return new ReceivedMqttPacket(fixedHeader.Flags, bodySegment, fixedHeader.TotalLength);
@@ -455,7 +459,7 @@ namespace MQTTnet.Adapter
            throw new MqttCommunicationException(exception);
        }

-        private struct Statistics
+        struct Statistics
        {
            public long _bytesReceived;
            public long _bytesSent;
@@ -11,112 +11,110 @@ namespace MQTTnet.Client
    public sealed class MqttClientConnectResult
    {
        /// <summary>
-        ///     Gets the client identifier which was chosen by the server.
-        ///     MQTTv5 only.
-        /// </summary>
-        public string AssignedClientIdentifier { get; internal set; }
-
-        /// <summary>
-        ///     Gets the authentication data.
-        ///     MQTTv5 only.
-        /// </summary>
-        public byte[] AuthenticationData { get; internal set; }
-
-        /// <summary>
-        ///     Gets the authentication method.
-        ///     MQTTv5 only.
-        /// </summary>
-        public string AuthenticationMethod { get; internal set; }
-
-        /// <summary>
-        ///     Gets a value indicating whether a session was already available or not.
-        ///     MQTTv5 only.
-        /// </summary>
-        public bool IsSessionPresent { get; internal set; }
-
-        public uint? MaximumPacketSize { get; internal set; }
-
-        /// <summary>
-        ///     Gets the maximum QoS which is supported by the server.
-        ///     MQTTv5 only.
-        /// </summary>
-        public MqttQualityOfServiceLevel MaximumQoS { get; internal set; }
-
-        /// <summary>
-        ///     Gets the reason string.
-        ///     MQTTv5 only.
-        /// </summary>
-        public string ReasonString { get; internal set; }
-
-        public ushort? ReceiveMaximum { get; internal set; }
-
-        /// <summary>
-        ///     Gets the response information.
-        ///     MQTTv5 only.
-        /// </summary>
-        public string ResponseInformation { get; internal set; }
-
-        /// <summary>
-        ///     Gets the result code.
-        ///     MQTTv5 only.
+        /// Gets the result code.
+        /// MQTTv5 only.
        /// </summary>
        public MqttClientConnectResultCode ResultCode { get; internal set; }

        /// <summary>
-        ///     Gets whether the server supports retained messages.
-        ///     MQTTv5 only.
+        /// Gets a value indicating whether a session was already available or not.
+        /// MQTTv5 only.
+        /// </summary>
+        public bool IsSessionPresent { get; internal set; }
+
+        /// <summary>
+        /// Gets a value indicating whether wildcards can be used in subscriptions at the current server.
+        /// MQTTv5 only.
+        /// </summary>
+        public bool WildcardSubscriptionAvailable { get; internal set; }
+
+        /// <summary>
+        /// Gets whether the server supports retained messages.
+        /// MQTTv5 only.
        /// </summary>
        public bool RetainAvailable { get; internal set; }

        /// <summary>
-        ///     MQTTv5 only.
-        ///     Gets the keep alive interval which was chosen by the server instead of the
-        ///     keep alive interval from the client CONNECT packet.
-        ///     A value of 0 indicates that the feature is not used.
+        /// Gets the client identifier which was chosen by the server.
+        /// MQTTv5 only.
        /// </summary>
-        public ushort ServerKeepAlive { get; internal set; }
+        public string AssignedClientIdentifier { get; internal set; }

        /// <summary>
-        ///     Gets an alternate server which should be used instead of the current one.
-        ///     MQTTv5 only.
+        /// Gets the authentication method.
+        /// MQTTv5 only.
        /// </summary>
-        public string ServerReference { get; internal set; }
-
-        public uint? SessionExpiryInterval { get; internal set; }
+        public string AuthenticationMethod { get; internal set; }

        /// <summary>
-        ///     Gets a value indicating whether the shared subscriptions are available or not.
-        ///     MQTTv5 only.
+        /// Gets the authentication data.
+        /// MQTTv5 only.
        /// </summary>
-        public bool SharedSubscriptionAvailable { get; internal set; }
+        public byte[] AuthenticationData { get; internal set; }
+
+        public uint? MaximumPacketSize { get; internal set; }

        /// <summary>
-        ///     Gets a value indicating whether the subscription identifiers are available or not.
-        ///     MQTTv5 only.
+        /// Gets the reason string.
+        /// MQTTv5 only.
        /// </summary>
-        public bool SubscriptionIdentifiersAvailable { get; internal set; }
+        public string ReasonString { get; internal set; }
+
+        public ushort? ReceiveMaximum { get; internal set; }
+        
+        /// <summary>
+        /// Gets the maximum QoS which is supported by the server.
+        /// MQTTv5 only.
+        /// </summary>
+        public MqttQualityOfServiceLevel MaximumQoS { get; internal set; }

        /// <summary>
-        ///     Gets the maximum value for a topic alias. 0 means not supported.
-        ///     MQTTv5 only.
+        /// Gets the response information.
+        /// MQTTv5 only.
+        /// </summary>
+        public string ResponseInformation { get; internal set; }
+
+        /// <summary>
+        /// Gets the maximum value for a topic alias. 0 means not supported.
+        /// MQTTv5 only.
        /// </summary>
        public ushort TopicAliasMaximum { get; internal set; }

        /// <summary>
-        ///     Gets the user properties.
-        ///     In MQTT 5, user properties are basic UTF-8 string key-value pairs that you can append to almost every type of MQTT
-        ///     packet.
-        ///     As long as you don’t exceed the maximum message size, you can use an unlimited number of user properties to add
-        ///     metadata to MQTT messages and pass information between publisher, broker, and subscriber.
-        ///     The feature is very similar to the HTTP header concept.
-        ///     MQTTv5 only.
+        /// Gets an alternate server which should be used instead of the current one.
+        /// MQTTv5 only.
        /// </summary>
-        public List<MqttUserProperty> UserProperties { get; internal set; }
+        public string ServerReference { get; internal set; }

        /// <summary>
-        ///     Gets a value indicating whether wildcards can be used in subscriptions at the current server.
-        ///     MQTTv5 only.
+        /// MQTTv5 only.
+        /// Gets the keep alive interval which was chosen by the server instead of the
+        /// keep alive interval from the client CONNECT packet.
+        /// A value of 0 indicates that the feature is not used.
        /// </summary>
-        public bool WildcardSubscriptionAvailable { get; internal set; }
+        public ushort ServerKeepAlive { get; internal set; }
+
+        public uint? SessionExpiryInterval { get; internal set; }
+
+        /// <summary>
+        /// Gets a value indicating whether the subscription identifiers are available or not.
+        /// MQTTv5 only.
+        /// </summary>
+        public bool SubscriptionIdentifiersAvailable { get; internal set; }
+
+        /// <summary>
+        /// Gets a value indicating whether the shared subscriptions are available or not.
+        /// MQTTv5 only.
+        /// </summary>
+        public bool SharedSubscriptionAvailable { get; internal set; }
+
+        /// <summary>
+        /// Gets the user properties.
+        /// In MQTT 5, user properties are basic UTF-8 string key-value pairs that you can append to almost every type of MQTT packet.
+        /// As long as you don’t exceed the maximum message size, you can use an unlimited number of user properties to add metadata to MQTT messages and pass information between publisher, broker, and subscriber.
+        /// The feature is very similar to the HTTP header concept.
+        /// MQTTv5 only.
+        /// </summary>
+        public List<MqttUserProperty> UserProperties { get; internal set; }
    }
-}
+}
@@ -9,14 +9,9 @@ namespace MQTTnet.Client
 {
    public sealed class MqttClientDisconnectOptions
    {
-        /// <summary>
-        /// Gets or sets whether this disconnect is a clean disconnect.
-        /// </summary>
-        public bool IsClean { get; set; }
-        
        /// <summary>
        ///     Gets or sets the reason code.
-        ///     Hint: MQTT 5 feature only.
+        ///     <remarks>MQTT 5.0.0+ feature.</remarks>
        /// </summary>
        public MqttClientDisconnectOptionsReason Reason { get; set; } = MqttClientDisconnectOptionsReason.NormalDisconnection;

@@ -15,7 +15,7 @@ namespace MQTTnet.Client

        event Func<MqttClientDisconnectedEventArgs, Task> DisconnectedAsync;

-        event Func<InspectMqttPacketEventArgs, Task> InspectPackage;
+        event Func<InspectMqttPacketEventArgs, Task> InspectPacketAsync;

        bool IsConnected { get; }

@@ -0,0 +1,18 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using MQTTnet.Diagnostics;
+using MQTTnet.Internal;
+
+namespace MQTTnet.Client.Internal
+{
+    public sealed class MqttClientEvents
+    {
+        public AsyncEvent<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceivedEvent { get; } = new AsyncEvent<MqttApplicationMessageReceivedEventArgs>();
+        public AsyncEvent<MqttClientConnectedEventArgs> ConnectedEvent { get; } = new AsyncEvent<MqttClientConnectedEventArgs>();
+        public AsyncEvent<MqttClientConnectingEventArgs> ConnectingEvent { get; } = new AsyncEvent<MqttClientConnectingEventArgs>();
+        public AsyncEvent<MqttClientDisconnectedEventArgs> DisconnectedEvent { get; } = new AsyncEvent<MqttClientDisconnectedEventArgs>();
+        public AsyncEvent<InspectMqttPacketEventArgs> InspectPacketEvent { get; } = new AsyncEvent<InspectMqttPacketEventArgs>();
+    }
+}
@@ -0,0 +1,14 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace MQTTnet.Client.Internal
+{
+    public static class MqttClientResultFactory
+    {
+        public static readonly MqttClientConnectResultFactory ConnectResult = new MqttClientConnectResultFactory();
+        public static readonly MqttClientPublishResultFactory PublishResult = new MqttClientPublishResultFactory();
+        public static readonly MqttClientSubscribeResultFactory SubscribeResult = new MqttClientSubscribeResultFactory();
+        public static readonly MqttClientUnsubscribeResultFactory UnsubscribeResult = new MqttClientUnsubscribeResultFactory();
+    }
+}
@@ -7,6 +7,7 @@ using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Adapter;
+using MQTTnet.Client.Internal;
 using MQTTnet.Diagnostics;
 using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
@@ -20,17 +21,9 @@ namespace MQTTnet.Client
    public sealed class MqttClient : Disposable, IMqttClient
    {
        readonly IMqttClientAdapterFactory _adapterFactory;
-        readonly AsyncEvent<MqttApplicationMessageReceivedEventArgs> _applicationMessageReceivedEvent = new AsyncEvent<MqttApplicationMessageReceivedEventArgs>();

-        readonly MqttClientPublishResultFactory _clientPublishResultFactory = new MqttClientPublishResultFactory();
-        readonly MqttClientSubscribeResultFactory _clientSubscribeResultFactory = new MqttClientSubscribeResultFactory();
-        readonly MqttClientUnsubscribeResultFactory _clientUnsubscribeResultFactory = new MqttClientUnsubscribeResultFactory();
-
-        readonly AsyncEvent<MqttClientConnectedEventArgs> _connectedEvent = new AsyncEvent<MqttClientConnectedEventArgs>();
-        readonly AsyncEvent<MqttClientConnectingEventArgs> _connectingEvent = new AsyncEvent<MqttClientConnectingEventArgs>();
-        readonly AsyncEvent<MqttClientDisconnectedEventArgs> _disconnectedEvent = new AsyncEvent<MqttClientDisconnectedEventArgs>();
        readonly object _disconnectLock = new object();
-        readonly AsyncEvent<InspectMqttPacketEventArgs> _inspectPacketEvent = new AsyncEvent<InspectMqttPacketEventArgs>();
+        readonly MqttClientEvents _events = new MqttClientEvents();
        readonly MqttNetSourceLogger _logger;

        readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
@@ -65,35 +58,35 @@ namespace MQTTnet.Client

        public event Func<MqttApplicationMessageReceivedEventArgs, Task> ApplicationMessageReceivedAsync
        {
-            add => _applicationMessageReceivedEvent.AddHandler(value);
-            remove => _applicationMessageReceivedEvent.RemoveHandler(value);
+            add => _events.ApplicationMessageReceivedEvent.AddHandler(value);
+            remove => _events.ApplicationMessageReceivedEvent.RemoveHandler(value);
        }

        public event Func<MqttClientConnectedEventArgs, Task> ConnectedAsync
        {
-            add => _connectedEvent.AddHandler(value);
-            remove => _connectedEvent.RemoveHandler(value);
+            add => _events.ConnectedEvent.AddHandler(value);
+            remove => _events.ConnectedEvent.RemoveHandler(value);
        }

        public event Func<MqttClientConnectingEventArgs, Task> ConnectingAsync
        {
-            add => _connectingEvent.AddHandler(value);
-            remove => _connectingEvent.RemoveHandler(value);
+            add => _events.ConnectingEvent.AddHandler(value);
+            remove => _events.ConnectingEvent.RemoveHandler(value);
        }

        public event Func<MqttClientDisconnectedEventArgs, Task> DisconnectedAsync
        {
-            add => _disconnectedEvent.AddHandler(value);
-            remove => _disconnectedEvent.RemoveHandler(value);
+            add => _events.DisconnectedEvent.AddHandler(value);
+            remove => _events.DisconnectedEvent.RemoveHandler(value);
        }

-        public event Func<InspectMqttPacketEventArgs, Task> InspectPackage
+        public event Func<InspectMqttPacketEventArgs, Task> InspectPacketAsync
        {
-            add => _inspectPacketEvent.AddHandler(value);
-            remove => _inspectPacketEvent.RemoveHandler(value);
+            add => _events.InspectPacketEvent.AddHandler(value);
+            remove => _events.InspectPacketEvent.RemoveHandler(value);
        }

-        public bool IsConnected => _adapter != null && (MqttClientConnectionStatus)_connectionStatus == MqttClientConnectionStatus.Connected;
+        public bool IsConnected => (MqttClientConnectionStatus)_connectionStatus == MqttClientConnectionStatus.Connected;

        public MqttClientOptions Options { get; private set; }

@@ -114,9 +107,9 @@ namespace MQTTnet.Client
            {
                Options = options;

-                if (_connectingEvent.HasHandlers)
+                if (_events.ConnectingEvent.HasHandlers)
                {
-                    await _connectingEvent.InvokeAsync(new MqttClientConnectingEventArgs(options)).ConfigureAwait(false);
+                    await _events.ConnectingEvent.InvokeAsync(new MqttClientConnectingEventArgs(options));
                }

                Cleanup();
@@ -127,12 +120,12 @@ namespace MQTTnet.Client
                _mqttClientAlive = new CancellationTokenSource();
                var mqttClientAliveToken = _mqttClientAlive.Token;

-                var adapter = _adapterFactory.CreateClientAdapter(options, new MqttPacketInspector(_inspectPacketEvent, _rootLogger), _rootLogger);
-                _adapter = adapter;
+                var adapter = _adapterFactory.CreateClientAdapter(options, new MqttPacketInspector(_events.InspectPacketEvent, _rootLogger), _rootLogger);
+                _adapter = adapter ?? throw new InvalidOperationException("The adapter factory did not provide an adapter.");

                if (cancellationToken.CanBeCanceled)
                {
-                    connectResult = await ConnectInternal(cancellationToken).ConfigureAwait(false);
+                    connectResult = await ConnectInternal(adapter, cancellationToken).ConfigureAwait(false);
                }
                else
                {
@@ -140,46 +133,50 @@ namespace MQTTnet.Client
                    // CancellationToken.None or similar.
                    using (var timeout = new CancellationTokenSource(Options.Timeout))
                    {
-                        connectResult = await ConnectInternal(timeout.Token).ConfigureAwait(false);
+                        connectResult = await ConnectInternal(adapter, timeout.Token).ConfigureAwait(false);
                    }
                }

+                if (connectResult.ResultCode != MqttClientConnectResultCode.Success)
+                {
+                    _logger.Warning("Connecting failed: {0}", connectResult.ResultCode);
+                    return connectResult;
+                }
+
                _lastPacketSentTimestamp = DateTime.UtcNow;

                var keepAliveInterval = Options.KeepAlivePeriod;
                if (connectResult.ServerKeepAlive > 0)
                {
-                    _logger.Info($"Using keep alive value ({connectResult.ServerKeepAlive}) sent from the server.");
+                    _logger.Info($"Using keep alive value ({connectResult.ServerKeepAlive}) sent from the server");
                    keepAliveInterval = TimeSpan.FromSeconds(connectResult.ServerKeepAlive);
                }

                if (keepAliveInterval != TimeSpan.Zero)
                {
-                    _keepAlivePacketsSenderTask = Task.Run(() => TrySendKeepAliveMessagesAsync(mqttClientAliveToken), mqttClientAliveToken);
+                    _keepAlivePacketsSenderTask = Task.Run(() => TrySendKeepAliveMessages(mqttClientAliveToken), mqttClientAliveToken);
                }

                CompareExchangeConnectionStatus(MqttClientConnectionStatus.Connected, MqttClientConnectionStatus.Connecting);

-                _logger.Info("Connected.");
+                _logger.Info("Connected");

-                if (_connectedEvent.HasHandlers)
-                {
-                    var eventArgs = new MqttClientConnectedEventArgs(connectResult);
-                    await _connectedEvent.InvokeAsync(eventArgs).ConfigureAwait(false);
-                }
+                await OnConnected(connectResult).ConfigureAwait(false);

                return connectResult;
            }
            catch (Exception exception)
            {
-                _disconnectReason = (int)MqttClientDisconnectOptionsReason.UnspecifiedError;
-
-                if (!(exception is OperationCanceledException))
+                if (exception is MqttConnectingFailedException connectingFailedException)
                {
-                    _logger.Error(exception, "Error while connecting with server.");
+                    connectResult = connectingFailedException.Result;
                }

-                await DisconnectInternalAsync(null, exception, connectResult).ConfigureAwait(false);
+                _disconnectReason = (int)MqttClientDisconnectOptionsReason.UnspecifiedError;
+
+                _logger.Error(exception, "Error while connecting with server");
+
+                await DisconnectInternal(null, exception, connectResult).ConfigureAwait(false);

                throw;
            }
@@ -222,19 +219,19 @@ namespace MQTTnet.Client

                if (cancellationToken.CanBeCanceled)
                {
-                    await SendAsync(disconnectPacket, cancellationToken).ConfigureAwait(false);
+                    await Send(disconnectPacket, cancellationToken).ConfigureAwait(false);
                }
                else
                {
                    using (var timeout = new CancellationTokenSource(Options.Timeout))
                    {
-                        await SendAsync(disconnectPacket, timeout.Token).ConfigureAwait(false);
+                        await Send(disconnectPacket, timeout.Token).ConfigureAwait(false);
                    }
                }
            }
            finally
            {
-                await DisconnectCoreAsync(null, null, null, clientWasConnected).ConfigureAwait(false);
+                await DisconnectCore(null, null, null, clientWasConnected).ConfigureAwait(false);
            }
        }

@@ -242,13 +239,13 @@ namespace MQTTnet.Client
        {
            if (cancellationToken.CanBeCanceled)
            {
-                await SendAndReceiveAsync<MqttPingRespPacket>(MqttPingReqPacket.Instance, cancellationToken).ConfigureAwait(false);
+                await Request<MqttPingRespPacket>(MqttPingReqPacket.Instance, cancellationToken).ConfigureAwait(false);
            }
            else
            {
                using (var timeout = new CancellationTokenSource(Options.Timeout))
                {
-                    await SendAndReceiveAsync<MqttPingRespPacket>(MqttPingReqPacket.Instance, timeout.Token).ConfigureAwait(false);
+                    await Request<MqttPingRespPacket>(MqttPingReqPacket.Instance, timeout.Token).ConfigureAwait(false);
                }
            }
        }
@@ -277,11 +274,11 @@ namespace MQTTnet.Client
                }
                case MqttQualityOfServiceLevel.AtLeastOnce:
                {
-                    return PublishAtLeastOnceAsync(publishPacket, cancellationToken);
+                    return PublishAtLeastOnce(publishPacket, cancellationToken);
                }
                case MqttQualityOfServiceLevel.ExactlyOnce:
                {
-                    return PublishExactlyOnceAsync(publishPacket, cancellationToken);
+                    return PublishExactlyOnce(publishPacket, cancellationToken);
                }
                default:
                {
@@ -309,7 +306,7 @@ namespace MQTTnet.Client
                UserProperties = data.UserProperties
            };

-            return SendAsync(authPacket, cancellationToken);
+            return Send(authPacket, cancellationToken);
        }

        public async Task<MqttClientSubscribeResult> SubscribeAsync(MqttClientSubscribeOptions options, CancellationToken cancellationToken = default)
@@ -338,17 +335,17 @@ namespace MQTTnet.Client
            MqttSubAckPacket subAckPacket;
            if (cancellationToken.CanBeCanceled)
            {
-                subAckPacket = await SendAndReceiveAsync<MqttSubAckPacket>(subscribePacket, cancellationToken).ConfigureAwait(false);
+                subAckPacket = await Request<MqttSubAckPacket>(subscribePacket, cancellationToken).ConfigureAwait(false);
            }
            else
            {
                using (var timeout = new CancellationTokenSource(Options.Timeout))
                {
-                    subAckPacket = await SendAndReceiveAsync<MqttSubAckPacket>(subscribePacket, timeout.Token).ConfigureAwait(false);
+                    subAckPacket = await Request<MqttSubAckPacket>(subscribePacket, timeout.Token).ConfigureAwait(false);
                }
            }

-            return _clientSubscribeResultFactory.Create(subscribePacket, subAckPacket);
+            return MqttClientResultFactory.SubscribeResult.Create(subscribePacket, subAckPacket);
        }

        public async Task<MqttClientUnsubscribeResult> UnsubscribeAsync(MqttClientUnsubscribeOptions options, CancellationToken cancellationToken = default)
@@ -377,17 +374,17 @@ namespace MQTTnet.Client
            MqttUnsubAckPacket unsubAckPacket;
            if (cancellationToken.CanBeCanceled)
            {
-                unsubAckPacket = await SendAndReceiveAsync<MqttUnsubAckPacket>(unsubscribePacket, cancellationToken).ConfigureAwait(false);
+                unsubAckPacket = await Request<MqttUnsubAckPacket>(unsubscribePacket, cancellationToken).ConfigureAwait(false);
            }
            else
            {
                using (var timeout = new CancellationTokenSource(Options.Timeout))
                {
-                    unsubAckPacket = await SendAndReceiveAsync<MqttUnsubAckPacket>(unsubscribePacket, timeout.Token).ConfigureAwait(false);
+                    unsubAckPacket = await Request<MqttUnsubAckPacket>(unsubscribePacket, timeout.Token).ConfigureAwait(false);
                }
            }

-            return _clientUnsubscribeResultFactory.Create(unsubscribePacket, unsubAckPacket);
+            return MqttClientResultFactory.UnsubscribeResult.Create(unsubscribePacket, unsubAckPacket);
        }

        protected override void Dispose(bool disposing)
@@ -411,7 +408,7 @@ namespace MQTTnet.Client
                if (!eventArgs.ProcessingFailed)
                {
                    var pubAckPacket = MqttPacketFactories.PubAck.Create(eventArgs);
-                    return SendAsync(pubAckPacket, cancellationToken);
+                    return Send(pubAckPacket, cancellationToken);
                }
            }
            else if (eventArgs.PublishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.ExactlyOnce)
@@ -419,7 +416,7 @@ namespace MQTTnet.Client
                if (!eventArgs.ProcessingFailed)
                {
                    var pubRecPacket = MqttPacketFactories.PubRec.Create(eventArgs);
-                    return SendAsync(pubRecPacket, cancellationToken);
+                    return Send(pubRecPacket, cancellationToken);
                }
            }
            else
@@ -430,27 +427,43 @@ namespace MQTTnet.Client
            return CompletedTask.Instance;
        }

-        async Task<MqttClientConnectResult> AuthenticateAsync(MqttClientOptions options, CancellationToken cancellationToken)
+        async Task<MqttClientConnectResult> Authenticate(IMqttChannelAdapter channelAdapter, MqttClientOptions options, CancellationToken cancellationToken)
        {
            MqttClientConnectResult result;

            try
            {
                var connectPacket = MqttPacketFactories.Connect.Create(options);
+                await Send(connectPacket, cancellationToken).ConfigureAwait(false);

-                var connAckPacket = await SendAndReceiveAsync<MqttConnAckPacket>(connectPacket, cancellationToken).ConfigureAwait(false);
+                var receivedPacket = await Receive(cancellationToken).ConfigureAwait(false);

-                var clientConnectResultFactory = new MqttClientConnectResultFactory();
-                result = clientConnectResultFactory.Create(connAckPacket, _adapter.PacketFormatterAdapter.ProtocolVersion);
+                if (receivedPacket is MqttConnAckPacket connAckPacket)
+                {
+                    result = MqttClientResultFactory.ConnectResult.Create(connAckPacket, _adapter.PacketFormatterAdapter.ProtocolVersion);
+                }
+                else
+                {
+                    throw new NotSupportedException("Extended authentication handler is not yet supported");
+                }
            }
            catch (Exception exception)
            {
                throw new MqttConnectingFailedException($"Error while authenticating. {exception.Message}", exception, null);
            }

-            if (result.ResultCode != MqttClientConnectResultCode.Success)
+            // This is no feature. It is basically a backward compatibility option and should be removed in the future.
+            // The client should not throw any exception if the transport layer connection was successful and the server
+            // did send a proper ACK packet with a non success response.
+            if (options.ThrowOnNonSuccessfulConnectResponse)
            {
-                throw new MqttConnectingFailedException($"Connecting with MQTT server failed ({result.ResultCode}).", null, result);
+                _logger.Warning(
+                    "Client will now throw an _MqttConnectingFailedException_. This is obsolete and will be removed in the future. Consider setting _ThrowOnNonSuccessfulResponseFromServer=False_ in client options.");
+
+                if (result.ResultCode != MqttClientConnectResultCode.Success)
+                {
+                    throw new MqttConnectingFailedException($"Connecting with MQTT server failed ({result.ResultCode}).", null, result);
+                }
            }

            _logger.Verbose("Authenticated MQTT connection with server established.");
@@ -485,27 +498,31 @@ namespace MQTTnet.Client
            return (MqttClientConnectionStatus)Interlocked.CompareExchange(ref _connectionStatus, (int)value, (int)comparand);
        }

-        async Task<MqttClientConnectResult> ConnectInternal(CancellationToken cancellationToken)
+        async Task<MqttClientConnectResult> ConnectInternal(IMqttChannelAdapter channelAdapter, CancellationToken cancellationToken)
        {
            var backgroundCancellationToken = _mqttClientAlive.Token;

            using (var effectiveCancellationToken = CancellationTokenSource.CreateLinkedTokenSource(backgroundCancellationToken, cancellationToken))
            {
-                _logger.Verbose("Trying to connect with server '{0}'.", Options.ChannelOptions);
+                _logger.Verbose("Trying to connect with server '{0}'", Options.ChannelOptions);
                await _adapter.ConnectAsync(effectiveCancellationToken.Token).ConfigureAwait(false);
-                _logger.Verbose("Connection with server established.");
+                _logger.Verbose("Connection with server established");

                _publishPacketReceiverQueue?.Dispose();
                _publishPacketReceiverQueue = new AsyncQueue<MqttPublishPacket>();

-                _publishPacketReceiverTask = Task.Run(() => ProcessReceivedPublishPackets(backgroundCancellationToken), backgroundCancellationToken);
-                _packetReceiverTask = Task.Run(() => TryReceivePacketsAsync(backgroundCancellationToken), backgroundCancellationToken);
+                var connectResult = await Authenticate(channelAdapter, Options, effectiveCancellationToken.Token).ConfigureAwait(false);
+                if (connectResult.ResultCode == MqttClientConnectResultCode.Success)
+                {
+                    _publishPacketReceiverTask = Task.Run(() => ProcessReceivedPublishPackets(backgroundCancellationToken), backgroundCancellationToken);
+                    _packetReceiverTask = Task.Run(() => ReceivePacketsLoop(backgroundCancellationToken), backgroundCancellationToken);
+                }

-                return await AuthenticateAsync(Options, effectiveCancellationToken.Token).ConfigureAwait(false);
+                return connectResult;
            }
        }

-        async Task DisconnectCoreAsync(Task sender, Exception exception, MqttClientConnectResult connectResult, bool clientWasConnected)
+        async Task DisconnectCore(Task sender, Exception exception, MqttClientConnectResult connectResult, bool clientWasConnected)
        {
            TryInitiateDisconnect();

@@ -560,17 +577,17 @@ namespace MQTTnet.Client

                // This handler must be executed in a new thread because otherwise a dead lock may happen
                // when trying to reconnect in that handler etc.
-                Task.Run(() => _disconnectedEvent.InvokeAsync(eventArgs)).RunInBackground(_logger);
+                Task.Run(() => _events.DisconnectedEvent.InvokeAsync(eventArgs)).RunInBackground(_logger);
            }
        }

-        Task DisconnectInternalAsync(Task sender, Exception exception, MqttClientConnectResult connectResult)
+        Task DisconnectInternal(Task sender, Exception exception, MqttClientConnectResult connectResult)
        {
            var clientWasConnected = IsConnected;

            if (!DisconnectIsPendingOrFinished())
            {
-                return DisconnectCoreAsync(sender, exception, connectResult, clientWasConnected);
+                return DisconnectCore(sender, exception, connectResult, clientWasConnected);
            }

            return CompletedTask.Instance;
@@ -600,8 +617,7 @@ namespace MQTTnet.Client
                        connectionStatus = curStatus;
                        break;
                }
-            }
-            while (true);
+            } while (true);
        }

        void EnqueueReceivedPublishPacket(MqttPublishPacket publishPacket)
@@ -616,15 +632,26 @@ namespace MQTTnet.Client
            }
        }

-        async Task<MqttApplicationMessageReceivedEventArgs> HandleReceivedApplicationMessageAsync(MqttPublishPacket publishPacket)
+        async Task<MqttApplicationMessageReceivedEventArgs> HandleReceivedApplicationMessage(MqttPublishPacket publishPacket)
        {
            var applicationMessage = MqttApplicationMessageFactory.Create(publishPacket);
            var eventArgs = new MqttApplicationMessageReceivedEventArgs(Options.ClientId, applicationMessage, publishPacket, AcknowledgeReceivedPublishPacket);
-            await _applicationMessageReceivedEvent.InvokeAsync(eventArgs).ConfigureAwait(false);
+            await _events.ApplicationMessageReceivedEvent.InvokeAsync(eventArgs).ConfigureAwait(false);

            return eventArgs;
        }

+        Task OnConnected(MqttClientConnectResult connectResult)
+        {
+            if (_events.ConnectedEvent.HasHandlers)
+            {
+                var eventArgs = new MqttClientConnectedEventArgs(connectResult);
+                return _events.ConnectedEvent.InvokeAsync(eventArgs);
+            }
+
+            return CompletedTask.Instance;
+        }
+
        Task ProcessReceivedAuthPacket(MqttAuthPacket authPacket)
        {
            var extendedAuthenticationExchangeHandler = Options.ExtendedAuthenticationExchangeHandler;
@@ -645,7 +672,7 @@ namespace MQTTnet.Client
            // Also dispatch disconnect to waiting threads to generate a proper exception.
            _packetDispatcher.Dispose(new MqttClientUnexpectedDisconnectReceivedException(disconnectPacket));

-            return DisconnectInternalAsync(_packetReceiverTask, null, null);
+            return DisconnectInternal(_packetReceiverTask, null, null);
        }

        async Task ProcessReceivedPublishPackets(CancellationToken cancellationToken)
@@ -661,7 +688,7 @@ namespace MQTTnet.Client
                    }

                    var publishPacket = publishPacketDequeueResult.Item;
-                    var eventArgs = await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false);
+                    var eventArgs = await HandleReceivedApplicationMessage(publishPacket).ConfigureAwait(false);

                    if (eventArgs.AutoAcknowledge)
                    {
@@ -685,7 +712,7 @@ namespace MQTTnet.Client
                // The packet is unknown. Probably due to a restart of the client.
                // So wen send this to the server to trigger a full resend of the message.
                var pubRelPacket = MqttPacketFactories.PubRel.Create(pubRecPacket, MqttApplicationMessageReceivedReasonCode.PacketIdentifierNotFound);
-                return SendAsync(pubRelPacket, cancellationToken);
+                return Send(pubRelPacket, cancellationToken);
            }

            return CompletedTask.Instance;
@@ -694,42 +721,117 @@ namespace MQTTnet.Client
        Task ProcessReceivedPubRelPacket(MqttPubRelPacket pubRelPacket, CancellationToken cancellationToken)
        {
            var pubCompPacket = MqttPacketFactories.PubComp.Create(pubRelPacket, MqttApplicationMessageReceivedReasonCode.Success);
-            return SendAsync(pubCompPacket, cancellationToken);
+            return Send(pubCompPacket, cancellationToken);
        }

-        async Task<MqttClientPublishResult> PublishAtLeastOnceAsync(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
+        async Task<MqttClientPublishResult> PublishAtLeastOnce(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
        {
            publishPacket.PacketIdentifier = _packetIdentifierProvider.GetNextPacketIdentifier();

-            var pubAckPacket = await SendAndReceiveAsync<MqttPubAckPacket>(publishPacket, cancellationToken).ConfigureAwait(false);
-            return _clientPublishResultFactory.Create(pubAckPacket);
+            var pubAckPacket = await Request<MqttPubAckPacket>(publishPacket, cancellationToken).ConfigureAwait(false);
+            return MqttClientResultFactory.PublishResult.Create(pubAckPacket);
        }

        async Task<MqttClientPublishResult> PublishAtMostOnce(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
        {
            // No packet identifier is used for QoS 0 [3.3.2.2 Packet Identifier]
-            await SendAsync(publishPacket, cancellationToken).ConfigureAwait(false);
+            await Send(publishPacket, cancellationToken).ConfigureAwait(false);

-            return _clientPublishResultFactory.Create(null);
+            return MqttClientResultFactory.PublishResult.Create(null);
        }

-        async Task<MqttClientPublishResult> PublishExactlyOnceAsync(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
+        async Task<MqttClientPublishResult> PublishExactlyOnce(MqttPublishPacket publishPacket, CancellationToken cancellationToken)
        {
            publishPacket.PacketIdentifier = _packetIdentifierProvider.GetNextPacketIdentifier();

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

            var pubRelPacket = MqttPacketFactories.PubRel.Create(pubRecPacket, MqttApplicationMessageReceivedReasonCode.Success);

-            var pubCompPacket = await SendAndReceiveAsync<MqttPubCompPacket>(pubRelPacket, cancellationToken).ConfigureAwait(false);
+            var pubCompPacket = await Request<MqttPubCompPacket>(pubRelPacket, cancellationToken).ConfigureAwait(false);

-            return _clientPublishResultFactory.Create(pubRecPacket, pubCompPacket);
+            return MqttClientResultFactory.PublishResult.Create(pubRecPacket, pubCompPacket);
        }

-        async Task<TResponsePacket> SendAndReceiveAsync<TResponsePacket>(MqttPacket requestPacket, CancellationToken cancellationToken) where TResponsePacket : MqttPacket
+        async Task<MqttPacket> Receive(CancellationToken cancellationToken)
+        {
+            var packetTask = _adapter.ReceivePacketAsync(cancellationToken);
+
+            MqttPacket packet;
+            if (packetTask.IsCompleted)
+            {
+                packet = packetTask.Result;
+            }
+            else
+            {
+                packet = await packetTask.ConfigureAwait(false);
+            }
+
+            return packet;
+        }
+
+        async Task ReceivePacketsLoop(CancellationToken cancellationToken)
+        {
+            try
+            {
+                _logger.Verbose("Start receiving packets.");
+
+                while (!cancellationToken.IsCancellationRequested)
+                {
+                    var packet = await Receive(cancellationToken).ConfigureAwait(false);
+
+                    if (cancellationToken.IsCancellationRequested)
+                    {
+                        return;
+                    }
+
+                    if (packet == null)
+                    {
+                        await DisconnectInternal(_packetReceiverTask, null, null).ConfigureAwait(false);
+
+                        return;
+                    }
+
+                    await TryProcessReceivedPacket(packet, cancellationToken).ConfigureAwait(false);
+                }
+            }
+            catch (Exception exception)
+            {
+                if (_cleanDisconnectInitiated)
+                {
+                    return;
+                }
+
+                if (exception is AggregateException aggregateException)
+                {
+                    exception = aggregateException.GetBaseException();
+                }
+
+                if (exception is OperationCanceledException)
+                {
+                }
+                else if (exception is MqttCommunicationException)
+                {
+                    _logger.Warning(exception, "Communication error while receiving packets.");
+                }
+                else
+                {
+                    _logger.Error(exception, "Error while receiving packets.");
+                }
+
+                _packetDispatcher.FailAll(exception);
+
+                await DisconnectInternal(_packetReceiverTask, exception, null).ConfigureAwait(false);
+            }
+            finally
+            {
+                _logger.Verbose("Stopped receiving packets.");
+            }
+        }
+
+        async Task<TResponsePacket> Request<TResponsePacket>(MqttPacket requestPacket, CancellationToken cancellationToken) where TResponsePacket : MqttPacket
        {
            cancellationToken.ThrowIfCancellationRequested();
-            ThrowIfNoAdapter();

            ushort packetIdentifier = 0;
            if (requestPacket is MqttPacketWithIdentifier packetWithIdentifier)
@@ -741,7 +843,7 @@ namespace MQTTnet.Client
            {
                try
                {
-                    await SendAsync(requestPacket, cancellationToken).ConfigureAwait(false);
+                    await Send(requestPacket, cancellationToken).ConfigureAwait(false);
                }
                catch (Exception exception)
                {
@@ -765,12 +867,12 @@ namespace MQTTnet.Client
            }
        }

-        Task SendAsync(MqttPacket packet, CancellationToken cancellationToken)
+        Task Send(MqttPacket packet, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
-            ThrowIfNoAdapter();

            _lastPacketSentTimestamp = DateTime.UtcNow;
+
            return _adapter.SendPacketAsync(packet, cancellationToken);
        }

@@ -782,16 +884,6 @@ namespace MQTTnet.Client
            }
        }

-        void ThrowIfNoAdapter()
-        {
-            // Having no adapter indicates that the connection is closed or still being created.
-            // Thus the client is disconnected.
-            if (_adapter == null)
-            {
-                ThrowNotConnected();
-            }
-        }
-
        void ThrowIfNotConnected()
        {
            if (!IsConnected)
@@ -838,7 +930,7 @@ namespace MQTTnet.Client
            }
        }

-        async Task TryProcessReceivedPacketAsync(MqttPacket packet, CancellationToken cancellationToken)
+        async Task TryProcessReceivedPacket(MqttPacket packet, CancellationToken cancellationToken)
        {
            try
            {
@@ -899,80 +991,11 @@ namespace MQTTnet.Client

                _packetDispatcher.FailAll(exception);

-                await DisconnectInternalAsync(_packetReceiverTask, exception, null).ConfigureAwait(false);
+                await DisconnectInternal(_packetReceiverTask, exception, null).ConfigureAwait(false);
            }
        }

-        async Task TryReceivePacketsAsync(CancellationToken cancellationToken)
-        {
-            try
-            {
-                _logger.Verbose("Start receiving packets.");
-
-                while (!cancellationToken.IsCancellationRequested)
-                {
-                    MqttPacket packet;
-                    var packetTask = _adapter.ReceivePacketAsync(cancellationToken);
-
-                    if (packetTask.IsCompleted)
-                    {
-                        packet = packetTask.Result;
-                    }
-                    else
-                    {
-                        packet = await packetTask.ConfigureAwait(false);
-                    }
-
-                    if (cancellationToken.IsCancellationRequested)
-                    {
-                        return;
-                    }
-
-                    if (packet == null)
-                    {
-                        await DisconnectInternalAsync(_packetReceiverTask, null, null).ConfigureAwait(false);
-
-                        return;
-                    }
-
-                    await TryProcessReceivedPacketAsync(packet, cancellationToken).ConfigureAwait(false);
-                }
-            }
-            catch (Exception exception)
-            {
-                if (_cleanDisconnectInitiated)
-                {
-                    return;
-                }
-
-                if (exception is AggregateException aggregateException)
-                {
-                    exception = aggregateException.GetBaseException();
-                }
-
-                if (exception is OperationCanceledException)
-                {
-                }
-                else if (exception is MqttCommunicationException)
-                {
-                    _logger.Warning(exception, "Communication error while receiving packets.");
-                }
-                else
-                {
-                    _logger.Error(exception, "Error while receiving packets.");
-                }
-
-                _packetDispatcher.FailAll(exception);
-
-                await DisconnectInternalAsync(_packetReceiverTask, exception, null).ConfigureAwait(false);
-            }
-            finally
-            {
-                _logger.Verbose("Stopped receiving packets.");
-            }
-        }
-
-        async Task TrySendKeepAliveMessagesAsync(CancellationToken cancellationToken)
+        async Task TrySendKeepAliveMessages(CancellationToken cancellationToken)
        {
            try
            {
@@ -1021,7 +1044,7 @@ namespace MQTTnet.Client
                    _logger.Error(exception, "Error exception while sending/receiving keep alive packets.");
                }

-                await DisconnectInternalAsync(_keepAlivePacketsSenderTask, exception, null).ConfigureAwait(false);
+                await DisconnectInternal(_keepAlivePacketsSenderTask, exception, null).ConfigureAwait(false);
            }
            finally
            {
@@ -12,6 +12,14 @@ namespace MQTTnet.Client
 {
    public sealed class MqttClientOptions
    {
+        /// <summary>
+        ///     Usually the MQTT packets can be send partially. This is done by using multiple TCP packets
+        ///     or WebSocket frames etc. Unfortunately not all brokers (like Amazon Web Services (AWS)) do support this feature and
+        ///     will close the connection when receiving such packets. If such a service is used this flag must
+        ///     be set to _false_.
+        /// </summary>
+        public bool AllowPacketFragmentation { get; set; } = true;
+
        /// <summary>
        ///     Gets or sets the authentication data.
        ///     <remarks>MQTT 5.0.0+ feature.</remarks>
@@ -92,6 +100,11 @@ namespace MQTTnet.Client
        /// </summary>
        public uint SessionExpiryInterval { get; set; }

+        /// <summary>
+        ///     Gets or sets whether an exception should be thrown when the server has sent a non success ACK packet.
+        /// </summary>
+        public bool ThrowOnNonSuccessfulConnectResponse { get; set; } = true;
+
        /// <summary>
        ///     Gets or sets the timeout which will be applied at socket level and internal operations.
        ///     The default value is the same as for sockets in .NET in general.
@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.

@@ -75,10 +75,20 @@ namespace MQTTnet.Client
            _options.ChannelOptions = (IMqttClientChannelOptions)_tcpOptions ?? _webSocketOptions;

            MqttClientOptionsValidator.ThrowIfNotSupported(_options);
-            
+
            return _options;
        }
-
+        
+        /// <summary>
+        /// The client will not throw an exception when the MQTT server responses with a non success ACK packet.
+        /// This will become the default behavior in future versions of the library.
+        /// </summary>
+        public MqttClientOptionsBuilder WithoutThrowOnNonSuccessfulConnectResponse()
+        {
+            _options.ThrowOnNonSuccessfulConnectResponse = false;
+            return this;
+        }
+        
        public MqttClientOptionsBuilder WithAuthentication(string method, byte[] data)
        {
            _options.AuthenticationMethod = method;
@@ -86,12 +96,24 @@ namespace MQTTnet.Client
            return this;
        }

+        /// <summary>
+        ///     Clean session is used in MQTT versions below 5.0.0. It is the same as setting "CleanStart".
+        /// </summary>
        public MqttClientOptionsBuilder WithCleanSession(bool value = true)
        {
            _options.CleanSession = value;
            return this;
        }

+        /// <summary>
+        ///     Clean start is used in MQTT versions 5.0.0 and higher. It is the same as setting "CleanSession".
+        /// </summary>
+        public MqttClientOptionsBuilder WithCleanStart(bool value = true)
+        {
+            _options.CleanSession = value;
+            return this;
+        }
+
        public MqttClientOptionsBuilder WithClientId(string value)
        {
            _options.ClientId = value;
@@ -188,6 +210,18 @@ namespace MQTTnet.Client
            return WithKeepAlivePeriod(TimeSpan.Zero);
        }

+        /// <summary>
+        ///     Usually the MQTT packets can be send partially. This is done by using multiple TCP packets
+        ///     or WebSocket frames etc. Unfortunately not all brokers (like Amazon Web Services (AWS)) do support this feature and
+        ///     will close the connection when receiving such packets. If such a service is used this flag must
+        ///     be set to _true_.
+        /// </summary>
+        public MqttClientOptionsBuilder WithoutPacketFragmentation()
+        {
+            _options.AllowPacketFragmentation = false;
+            return this;
+        }
+
        public MqttClientOptionsBuilder WithProtocolVersion(MqttProtocolVersion value)
        {
            if (value == MqttProtocolVersion.Unknown)
@@ -266,7 +300,7 @@ namespace MQTTnet.Client

            return this;
        }
-        
+
        public MqttClientOptionsBuilder WithTcpServer(Action<MqttClientTcpOptions> optionsBuilder)
        {
            if (optionsBuilder == null)
@@ -373,6 +407,18 @@ namespace MQTTnet.Client
            return this;
        }

+        public MqttClientOptionsBuilder WithWillContentType(string willContentType)
+        {
+            _options.WillContentType = willContentType;
+            return this;
+        }
+
+        public MqttClientOptionsBuilder WithWillCorrelationData(byte[] willCorrelationData)
+        {
+            _options.WillCorrelationData = willCorrelationData;
+            return this;
+        }
+
        public MqttClientOptionsBuilder WithWillDelayInterval(uint willDelayInterval)
        {
            _options.WillDelayInterval = willDelayInterval;
@@ -384,27 +430,45 @@ namespace MQTTnet.Client
            _options.WillPayload = willPayload;
            return this;
        }
-        
+
+        public MqttClientOptionsBuilder WithWillPayload(ArraySegment<byte> willPayload)
+        {
+            if (willPayload.Count == 0)
+            {
+                _options.WillPayload = null;
+                return this;
+            }
+
+            _options.WillPayload = willPayload.ToArray();
+            return this;
+        }
+
        public MqttClientOptionsBuilder WithWillPayload(string willPayload)
        {
            if (string.IsNullOrEmpty(willPayload))
            {
                return WithWillPayload((byte[])null);
            }
-            
+
            _options.WillPayload = Encoding.UTF8.GetBytes(willPayload);
            return this;
        }

+        public MqttClientOptionsBuilder WithWillPayloadFormatIndicator(MqttPayloadFormatIndicator willPayloadFormatIndicator)
+        {
+            _options.WillPayloadFormatIndicator = willPayloadFormatIndicator;
+            return this;
+        }
+
        public MqttClientOptionsBuilder WithWillQualityOfServiceLevel(MqttQualityOfServiceLevel willQualityOfServiceLevel)
        {
            _options.WillQualityOfServiceLevel = willQualityOfServiceLevel;
            return this;
        }

-        public MqttClientOptionsBuilder WithWillTopic(string willTopic)
+        public MqttClientOptionsBuilder WithWillResponseTopic(string willResponseTopic)
        {
-            _options.WillTopic = willTopic;
+            _options.WillResponseTopic = willResponseTopic;
            return this;
        }

@@ -413,38 +477,20 @@ namespace MQTTnet.Client
            _options.WillRetain = willRetain;
            return this;
        }
-        
-        public MqttClientOptionsBuilder WithWillContentType(string willContentType)
+
+        public MqttClientOptionsBuilder WithWillTopic(string willTopic)
        {
-            _options.WillContentType = willContentType;
+            _options.WillTopic = willTopic;
            return this;
        }
-        
-        public MqttClientOptionsBuilder WithWillCorrelationData(byte[] willCorrelationData)
-        {
-            _options.WillCorrelationData = willCorrelationData;
-            return this;
-        }
-        
-        public MqttClientOptionsBuilder WithWillResponseTopic(string willResponseTopic)
-        {
-            _options.WillResponseTopic = willResponseTopic;
-            return this;
-        }
-        
-        public MqttClientOptionsBuilder WithWillPayloadFormatIndicator(MqttPayloadFormatIndicator willPayloadFormatIndicator)
-        {
-            _options.WillPayloadFormatIndicator = willPayloadFormatIndicator;
-            return this;
-        }
-        
+
        public MqttClientOptionsBuilder WithWillUserProperty(string name, string value)
        {
            if (_options.WillUserProperties == null)
            {
                _options.WillUserProperties = new List<MqttUserProperty>();
            }
-            
+
            _options.WillUserProperties.Add(new MqttUserProperty(name, value));
            return this;
        }
@@ -4,6 +4,7 @@

 using System;
 using System.Collections.Generic;
+using System.Net.Security;
 using System.Security.Authentication;
 using System.Security.Cryptography.X509Certificates;

@@ -30,11 +31,21 @@ namespace MQTTnet.Client
 #endif

 #if NETCOREAPP3_1_OR_GREATER
-        public List<System.Net.Security.SslApplicationProtocol> ApplicationProtocols { get; set; }
-        
-        public System.Net.Security.CipherSuitesPolicy CipherSuitesPolicy { get; set; }
+        public List<SslApplicationProtocol> ApplicationProtocols { get; set; }
+
+        public CipherSuitesPolicy CipherSuitesPolicy { get; set; }
+
+        public EncryptionPolicy EncryptionPolicy { get; set; } = EncryptionPolicy.RequireEncryption;
+
+        public bool AllowRenegotiation { get; set; } = true;
 #endif

+        /// <summary>
+        ///     Gets or sets the target host.
+        ///     If the value is null or empty the same host as the TCP socket host will be used.
+        /// </summary>
+        public string TargetHost { get; set; }
+
 #if NET48 || NETCOREAPP3_1_OR_GREATER
        public SslProtocols SslProtocol { get; set; } = SslProtocols.Tls12 | SslProtocols.Tls13;
 #else
@@ -2,15 +2,19 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.

+using System;
 using System.Collections.Generic;
 using System.Net;
+using System.Net.WebSockets;

 namespace MQTTnet.Client
 {
    public sealed class MqttClientWebSocketOptions : IMqttClientChannelOptions
    {
        public CookieContainer CookieContainer { get; set; }
-        
+
+        public ICredentials Credentials { get; set; }
+
        public MqttClientWebSocketProxyOptions ProxyOptions { get; set; }

        public IDictionary<string, string> RequestHeaders { get; set; }
@@ -18,12 +22,34 @@ namespace MQTTnet.Client
        public ICollection<string> SubProtocols { get; set; } = new List<string> { "mqtt" };

        public MqttClientTlsOptions TlsOptions { get; set; } = new MqttClientTlsOptions();
-        
+
        public string Uri { get; set; }

        public override string ToString()
        {
            return Uri;
        }
+
+#if !NETSTANDARD1_3
+#if !WINDOWS_UWP
+        /// <summary>
+        ///     Gets or sets the keep alive interval for the Web Socket connection.
+        ///     This is not related to the keep alive interval for the MQTT protocol.
+        /// </summary>
+        public TimeSpan KeepAliveInterval { get; set; } = WebSocket.DefaultKeepAliveInterval;
+
+        /// <summary>
+        ///     Gets or sets whether the default (system) credentials should be used when connecting via Web Socket connection.
+        ///     This is not related to the credentials which are used for the MQTT protocol.
+        /// </summary>
+        public bool UseDefaultCredentials { get; set; }
+#else
+        /// <summary>
+        ///     Gets or sets the keep alive interval for the Web Socket connection.
+        ///     This is not related to the keep alive interval for the MQTT protocol.
+        /// </summary>
+        public TimeSpan KeepAliveInterval { get; set; } = TimeSpan.FromSeconds(30);
+#endif
+#endif
    }
 }
@@ -16,6 +16,8 @@ namespace MQTTnet.Client

        public bool BypassOnLocal { get; set; }

+        public bool UseDefaultCredentials { get; set; }
+
        public string[] BypassList { get; set; }
    }
 }
@@ -10,11 +10,7 @@ namespace MQTTnet.Client
 {
    public sealed class MqttClientSubscribeResult
    {
-        public MqttClientSubscribeResult(
-            ushort packetIdentifier,
-            IReadOnlyCollection<MqttClientSubscribeResultItem> items,
-            string reasonString,
-            IReadOnlyCollection<MqttUserProperty> userProperties)
+        public MqttClientSubscribeResult(ushort packetIdentifier, IReadOnlyCollection<MqttClientSubscribeResultItem> items, string reasonString, IReadOnlyCollection<MqttUserProperty> userProperties)
        {
            PacketIdentifier = packetIdentifier;
            Items = items ?? throw new ArgumentNullException(nameof(items));
@@ -23,26 +19,25 @@ namespace MQTTnet.Client
        }

        /// <summary>
-        ///     Gets the result for every topic filter item.
+        /// Gets the result for every topic filter item.
        /// </summary>
        public IReadOnlyCollection<MqttClientSubscribeResultItem> Items { get; }
-
+        
        /// <summary>
-        ///     Gets the user properties which were part of the SUBACK packet.
-        ///     MQTTv5 only.
+        /// Gets the user properties which were part of the SUBACK packet.
+        /// <remarks>MQTT 5.0.0+ feature.</remarks>
        /// </summary>
-        public ushort PacketIdentifier { get; }
-
+        public IReadOnlyCollection<MqttUserProperty> UserProperties { get; }
+        
        /// <summary>
-        ///     Gets the reason string.
-        ///     <remarks>MQTT 5.0.0+ feature.</remarks>
+        /// Gets the reason string.
+        /// <remarks>MQTT 5.0.0+ feature.</remarks>
        /// </summary>
        public string ReasonString { get; }

        /// <summary>
-        ///     Gets the user properties which were part of the SUBACK packet.
-        ///     <remarks>MQTT 5.0.0+ feature.</remarks>
+        /// Gets the packet identifier which was used.
        /// </summary>
-        public IReadOnlyCollection<MqttUserProperty> UserProperties { get; }
+        public ushort PacketIdentifier { get; }
    }
 }
@@ -27,4 +27,4 @@ namespace MQTTnet.Client
        /// </summary>
        public MqttClientSubscribeResultCode ResultCode { get; }
    }
-}
+}
@@ -42,6 +42,6 @@ namespace MQTTnet.Client
        ///     Gets the user properties which were part of the UNSUBACK packet.
        ///     <remarks>MQTT 5.0.0+ feature.</remarks>
        /// </summary>
-        public IReadOnlyCollection<MqttUserProperty> UserProperties { get; }
+        public IReadOnlyCollection<MqttUserProperty> UserProperties { get; set; }
    }
 }
@@ -101,13 +101,6 @@ namespace MQTTnet.Diagnostics

            logger.Publish(logLevel, message, new object[] { parameter1, parameter2 }, exception);
        }
-        
-        public static MqttNetSourceLogger WithSource<TSource>(this IMqttNetLogger logger)
-        {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
-
-            return new MqttNetSourceLogger(logger, typeof(TSource).Name);
-        }

        public static void Verbose<TParameter1>(this MqttNetSourceLogger logger, string message, TParameter1 parameter1)
        {
@@ -16,6 +16,8 @@ namespace MQTTnet.Diagnostics
                return "net461";
 #elif NET472
                return "net472";
+#elif NET48
+                return "net48";
 #elif NETSTANDARD1_3
                return "netstandard1.3";
 #elif NETSTANDARD2_0
@@ -19,7 +19,7 @@ namespace MQTTnet.Formatter
            return new MqttApplicationMessage
            {
                Topic = publishPacket.Topic,
-                Payload = publishPacket.Payload,
+                PayloadSegment = publishPacket.PayloadSegment,
                QualityOfServiceLevel = publishPacket.QualityOfServiceLevel,
                Retain = publishPacket.Retain,
                Dup = publishPacket.Dup,
@@ -19,7 +19,8 @@ namespace MQTTnet.Formatter
    /// </summary>
    public sealed class MqttBufferWriter
    {
-        public const uint VariableByteIntegerMaxValue = 268435455;
+        const uint VariableByteIntegerMaxValue = 268435455;
+        const int EncodedStringMaxLength = 65535;

        readonly int _maxBufferSize;

@@ -112,25 +113,7 @@ namespace MQTTnet.Formatter
            WriteBinary(propertyWriter._buffer, 0, propertyWriter.Length);
        }

-        public void WriteBinary(byte[] buffer, int offset, int count)
-        {
-            if (buffer == null)
-            {
-                throw new ArgumentNullException(nameof(buffer));
-            }
-
-            if (count == 0)
-            {
-                return;
-            }
-
-            EnsureAdditionalCapacity(count);
-
-            MqttMemoryHelper.Copy(buffer, offset, _buffer, _position, count);
-            IncreasePosition(count);
-        }
-
-        public void WriteBinaryData(byte[] value)
+        public void WriteBinary(byte[] value)
        {
            if (value == null || value.Length == 0)
            {
@@ -155,6 +138,24 @@ namespace MQTTnet.Formatter
            }
        }

+        public void WriteBinary(byte[] buffer, int offset, int count)
+        {
+            if (buffer == null)
+            {
+                throw new ArgumentNullException(nameof(buffer));
+            }
+
+            if (count == 0)
+            {
+                return;
+            }
+
+            EnsureAdditionalCapacity(count);
+
+            MqttMemoryHelper.Copy(buffer, offset, _buffer, _position, count);
+            IncreasePosition(count);
+        }
+
        public void WriteByte(byte @byte)
        {
            EnsureAdditionalCapacity(1);
@@ -186,6 +187,13 @@ namespace MQTTnet.Formatter

                var writtenBytes = Encoding.UTF8.GetBytes(value, 0, value.Length, _buffer, _position + 2);

+                // From RFC: 1.5.4 UTF-8 Encoded String
+                // Unless stated otherwise all UTF-8 encoded strings can have any length in the range 0 to 65,535 bytes.
+                if (writtenBytes > EncodedStringMaxLength)
+                {
+                    throw new MqttProtocolViolationException($"The maximum string length is 65535. The current string has a length of {writtenBytes}.");
+                }
+
                _buffer[_position] = (byte)(writtenBytes >> 8);
                _buffer[_position + 1] = (byte)writtenBytes;

@@ -273,8 +281,7 @@ namespace MQTTnet.Formatter
                newBufferLength *= 2;
            }

-            // Array.Resize will create a new array and copy the existing
-            // data to the new one.
+            // Array.Resize will create a new array and copy the existing data to the new one.
            Array.Resize(ref _buffer, newBufferLength);
        }

@@ -285,6 +292,8 @@ namespace MQTTnet.Formatter

            if (_position > Length)
            {
+                // Also extend the position because we reached the end of the 
+                // pre allocated buffer.
                Length = _position;
            }
        }
@@ -2,54 +2,12 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.

-using MQTTnet.Exceptions;
 using MQTTnet.Protocol;

 namespace MQTTnet.Formatter
 {
    public static class MqttConnectReasonCodeConverter
    {
-        public static MqttConnectReasonCode ToConnectReasonCode(MqttConnectReturnCode returnCode)
-        {
-            switch (returnCode)
-            {
-                case MqttConnectReturnCode.ConnectionAccepted:
-                {
-                    return MqttConnectReasonCode.Success;
-                }
-
-                case MqttConnectReturnCode.ConnectionRefusedUnacceptableProtocolVersion:
-                {
-                    return MqttConnectReasonCode.UnsupportedProtocolVersion;
-                }
-
-                case MqttConnectReturnCode.ConnectionRefusedBadUsernameOrPassword:
-                {
-                    return MqttConnectReasonCode.BadUserNameOrPassword;
-                }
-
-                case MqttConnectReturnCode.ConnectionRefusedIdentifierRejected:
-                {
-                    return MqttConnectReasonCode.ClientIdentifierNotValid;
-                }
-
-                case MqttConnectReturnCode.ConnectionRefusedServerUnavailable:
-                {
-                    return MqttConnectReasonCode.ServerUnavailable;
-                }
-
-                case MqttConnectReturnCode.ConnectionRefusedNotAuthorized:
-                {
-                    return MqttConnectReasonCode.NotAuthorized;
-                }
-
-                default:
-                {
-                    throw new MqttProtocolViolationException("Unable to convert connect reason code (MQTTv5) to return code (MQTTv3).");
-                }
-            }
-        }
-
        public static MqttConnectReturnCode ToConnectReturnCode(MqttConnectReasonCode reasonCode)
        {
            switch (reasonCode)
@@ -59,11 +17,13 @@ namespace MQTTnet.Formatter
                    return MqttConnectReturnCode.ConnectionAccepted;
                }

+                case MqttConnectReasonCode.Banned:
                case MqttConnectReasonCode.NotAuthorized:
                {
                    return MqttConnectReturnCode.ConnectionRefusedNotAuthorized;
                }

+                case MqttConnectReasonCode.BadAuthenticationMethod:
                case MqttConnectReasonCode.BadUserNameOrPassword:
                {
                    return MqttConnectReturnCode.ConnectionRefusedBadUsernameOrPassword;
@@ -79,6 +39,7 @@ namespace MQTTnet.Formatter
                    return MqttConnectReturnCode.ConnectionRefusedUnacceptableProtocolVersion;
                }

+                case MqttConnectReasonCode.UseAnotherServer:
                case MqttConnectReasonCode.ServerUnavailable:
                case MqttConnectReasonCode.ServerBusy:
                case MqttConnectReasonCode.ServerMoved:
@@ -87,9 +48,7 @@ namespace MQTTnet.Formatter
                }

                default:
-                {
-                    throw new MqttProtocolViolationException("Unable to convert connect reason code (MQTTv5) to return code (MQTTv3).");
-                }
+                    return MqttConnectReturnCode.ConnectionRefusedUnacceptableProtocolVersion;
            }
        }
    }
@@ -31,10 +31,14 @@ namespace MQTTnet.Formatter

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

+        public void Cleanup()
+        {
+            _bufferWriter.Cleanup();
+        }
+
        public MqttPacket Decode(ReceivedMqttPacket receivedMqttPacket)
        {
            ThrowIfFormatterNotSet();
-
            return _formatter.Decode(receivedMqttPacket);
        }

@@ -50,11 +54,6 @@ namespace MQTTnet.Formatter
            return _formatter.Encode(packet);
        }

-        public void Cleanup()
-        {
-            _bufferWriter.Cleanup();
-        }
-
        public static IMqttPacketFormatter GetMqttPacketFormatter(MqttProtocolVersion protocolVersion, MqttBufferWriter bufferWriter)
        {
            if (protocolVersion == MqttProtocolVersion.Unknown)
@@ -98,7 +97,7 @@ namespace MQTTnet.Formatter
            // Remove the mosquitto try_private flag (MQTT 3.1.1 Bridge).
            // This flag is accepted but not yet used.
            protocolLevel &= 0x7F;
-            
+
            if (protocolName == "MQTT")
            {
                if (protocolLevel == 5)
@@ -16,7 +16,7 @@ namespace MQTTnet.Formatter
            return new MqttPublishPacket
            {
                Topic = publishPacket.Topic,
-                Payload = publishPacket.Payload,
+                PayloadSegment = publishPacket.PayloadSegment, 
                Retain = publishPacket.Retain,
                QualityOfServiceLevel = publishPacket.QualityOfServiceLevel,
                Dup = publishPacket.Dup,
@@ -36,7 +36,7 @@ namespace MQTTnet.Formatter
            var packet = new MqttPublishPacket
            {
                Topic = applicationMessage.Topic,
-                Payload = applicationMessage.Payload,
+                PayloadSegment = applicationMessage.PayloadSegment, 
                QualityOfServiceLevel = applicationMessage.QualityOfServiceLevel,
                Retain = applicationMessage.Retain,
                Dup = applicationMessage.Dup,
@@ -65,10 +65,16 @@ namespace MQTTnet.Formatter
                throw new MqttProtocolViolationException("The CONNECT packet contains no will message (WillFlag).");
            }

+            ArraySegment<byte> willMessageBuffer = default;
+            if (connectPacket.WillMessage?.Length > 0)
+            {
+                willMessageBuffer = new ArraySegment<byte>(connectPacket.WillMessage);
+            }
+
            var packet = new MqttPublishPacket
            {
                Topic = connectPacket.WillTopic,
-                Payload = connectPacket.WillMessage,
+                PayloadSegment = willMessageBuffer,
                QualityOfServiceLevel = connectPacket.WillQoS,
                Retain = connectPacket.WillRetain,
                ContentType = connectPacket.WillContentType,
@@ -54,12 +54,12 @@ namespace MQTTnet.Formatter.V3
                    return DecodePubRelPacket(receivedMqttPacket.Body);
                case MqttControlPacketType.PubComp:
                    return DecodePubCompPacket(receivedMqttPacket.Body);
-                
+
                case MqttControlPacketType.PingReq:
                    return MqttPingReqPacket.Instance;
                case MqttControlPacketType.PingResp:
                    return MqttPingRespPacket.Instance;
-                
+
                case MqttControlPacketType.Connect:
                    return DecodeConnectPacket(receivedMqttPacket.Body);
                case MqttControlPacketType.ConnAck:
@@ -73,7 +73,7 @@ namespace MQTTnet.Formatter.V3
                    }
                case MqttControlPacketType.Disconnect:
                    return DisconnectPacket;
-                
+
                case MqttControlPacketType.Subscribe:
                    return DecodeSubscribePacket(receivedMqttPacket.Body);
                case MqttControlPacketType.SubAck:
@@ -103,9 +103,10 @@ namespace MQTTnet.Formatter.V3
            var remainingLength = (uint)(_bufferWriter.Length - 5);

            var publishPacket = packet as MqttPublishPacket;
-            if (publishPacket?.Payload != null)
+            var payloadSegment = publishPacket?.PayloadSegment;
+            if (payloadSegment != null)
            {
-                remainingLength += (uint)publishPacket.Payload.Length;
+                remainingLength += (uint)payloadSegment.Value.Count;
            }

            var remainingLengthSize = MqttBufferWriter.GetVariableByteIntegerSize(remainingLength);
@@ -119,18 +120,13 @@ namespace MQTTnet.Formatter.V3
            _bufferWriter.WriteVariableByteInteger(remainingLength);

            var buffer = _bufferWriter.GetBuffer();
-
            var firstSegment = new ArraySegment<byte>(buffer, headerOffset, _bufferWriter.Length - headerOffset);

-            if (publishPacket?.Payload != null)
-            {
-                var payloadSegment = new ArraySegment<byte>(publishPacket.Payload, 0, publishPacket.Payload.Length);
-                return new MqttPacketBuffer(firstSegment, payloadSegment);
-            }
-
-            return new MqttPacketBuffer(firstSegment);
+            return payloadSegment == null
+                ? new MqttPacketBuffer(firstSegment)
+                : new MqttPacketBuffer(firstSegment, payloadSegment.Value);
        }
-        
+
        MqttPacket DecodeConnAckPacket(ArraySegment<byte> body)
        {
            ThrowIfBodyIsEmpty(body);
@@ -177,7 +173,7 @@ namespace MQTTnet.Formatter.V3

            var tryPrivate = (protocolVersion & 0x80) > 0;
            protocolVersion &= 0x7F;
-            
+
            if (protocolVersion != 3 && protocolVersion != 4)
            {
                throw new MqttProtocolViolationException("MQTT protocol version do not match MQTT v3.");
@@ -282,7 +278,7 @@ namespace MQTTnet.Formatter.V3

            if (!_bufferReader.EndOfStream)
            {
-                packet.Payload = _bufferReader.ReadRemainingData();
+                packet.PayloadSegment = new ArraySegment<byte>(_bufferReader.ReadRemainingData());
            }

            return packet;
@@ -421,7 +417,7 @@ namespace MQTTnet.Formatter.V3
            {
                protocolVersion |= 0x80;
            }
-            
+
            bufferWriter.WriteByte((byte)protocolVersion);

            byte connectFlags = 0x0;
@@ -463,7 +459,7 @@ namespace MQTTnet.Formatter.V3
            if (packet.WillFlag)
            {
                bufferWriter.WriteString(packet.WillTopic);
-                bufferWriter.WriteBinaryData(packet.WillMessage);
+                bufferWriter.WriteBinary(packet.WillMessage);
            }

            if (packet.Username != null)
@@ -473,7 +469,7 @@ namespace MQTTnet.Formatter.V3

            if (packet.Password != null)
            {
-                bufferWriter.WriteBinaryData(packet.Password);
+                bufferWriter.WriteBinary(packet.Password);
            }

            return MqttBufferWriter.BuildFixedHeader(MqttControlPacketType.Connect);
@@ -525,7 +521,7 @@ namespace MQTTnet.Formatter.V3
            if (packet.WillFlag)
            {
                bufferWriter.WriteString(packet.WillTopic);
-                bufferWriter.WriteBinaryData(packet.WillMessage);
+                bufferWriter.WriteBinary(packet.WillMessage);
            }

            if (packet.Username != null)
@@ -535,7 +531,7 @@ namespace MQTTnet.Formatter.V3

            if (packet.Password != null)
            {
-                bufferWriter.WriteBinaryData(packet.Password);
+                bufferWriter.WriteBinary(packet.Password);
            }

            return MqttBufferWriter.BuildFixedHeader(MqttControlPacketType.Connect);
@@ -130,6 +130,9 @@ namespace MQTTnet.Formatter.V5
                MaximumQoS = MqttQualityOfServiceLevel.ExactlyOnce
            };

+            // Also set the return code of MQTT 3.1.1 for backward compatibility and debugging purposes.
+            packet.ReturnCode = MqttConnectReasonCodeConverter.ToConnectReturnCode(packet.ReasonCode);
+
            var propertiesReader = new MqttV5PropertiesReader(_bufferReader);
            while (propertiesReader.MoveNext())
            {
@@ -528,7 +531,7 @@ namespace MQTTnet.Formatter.V5

            if (!_bufferReader.EndOfStream)
            {
-                packet.Payload = _bufferReader.ReadRemainingData();
+                packet.PayloadSegment = new ArraySegment<byte>(_bufferReader.ReadRemainingData());
            }

            return packet;
@@ -37,9 +37,11 @@ namespace MQTTnet.Formatter.V5
            var remainingLength = (uint)_bufferWriter.Length - 5;

            var publishPacket = packet as MqttPublishPacket;
-            if (publishPacket?.Payload != null)
+            var payloadSegment = publishPacket?.PayloadSegment;
+
+            if (payloadSegment != null)
            {
-                remainingLength += (uint)publishPacket.Payload.Length;
+                remainingLength += (uint)payloadSegment.Value.Count;
            }

            var remainingLengthSize = MqttBufferWriter.GetVariableByteIntegerSize(remainingLength);
@@ -53,18 +55,13 @@ namespace MQTTnet.Formatter.V5
            _bufferWriter.WriteVariableByteInteger(remainingLength);

            var buffer = _bufferWriter.GetBuffer();
-
            var firstSegment = new ArraySegment<byte>(buffer, headerOffset, _bufferWriter.Length - headerOffset);

-            if (publishPacket?.Payload != null)
-            {
-                var payloadSegment = new ArraySegment<byte>(publishPacket.Payload, 0, publishPacket.Payload.Length);
-                return new MqttPacketBuffer(firstSegment, payloadSegment);
-            }
-
-            return new MqttPacketBuffer(firstSegment);
+            return payloadSegment == null
+               ? new MqttPacketBuffer(firstSegment)
+               : new MqttPacketBuffer(firstSegment, payloadSegment.Value);
        }
-        
+
        byte EncodeAuthPacket(MqttAuthPacket packet)
        {
            _bufferWriter.WriteByte((byte)packet.ReasonCode);
@@ -189,7 +186,7 @@ namespace MQTTnet.Formatter.V5
                _propertiesWriter.Reset();

                _bufferWriter.WriteString(packet.WillTopic);
-                _bufferWriter.WriteBinaryData(packet.WillMessage);
+                _bufferWriter.WriteBinary(packet.WillMessage);
            }

            if (packet.Username != null)
@@ -199,7 +196,7 @@ namespace MQTTnet.Formatter.V5

            if (packet.Password != null)
            {
-                _bufferWriter.WriteBinaryData(packet.Password);
+                _bufferWriter.WriteBinary(packet.Password);
            }

            return MqttBufferWriter.BuildFixedHeader(MqttControlPacketType.Connect);
@@ -335,7 +335,7 @@ namespace MQTTnet.Formatter.V5
            }

            _bufferWriter.WriteByte((byte)id);
-            _bufferWriter.WriteBinaryData(value);
+            _bufferWriter.WriteBinary(value);
        }

        void WriteAsFourByteInteger(MqttPropertyId id, uint value)
@@ -40,7 +40,12 @@ namespace MQTTnet.Implementations

            var bufferWriter = new MqttBufferWriter(options.WriterBufferSize, options.WriterBufferSizeMax);
            var packetFormatterAdapter = new MqttPacketFormatterAdapter(options.ProtocolVersion, bufferWriter);
-            return new MqttChannelAdapter(channel, packetFormatterAdapter, packetInspector, logger);
+
+            return new MqttChannelAdapter(channel, packetFormatterAdapter, logger)
+            {
+                AllowPacketFragmentation = options.AllowPacketFragmentation,
+                PacketInspector = packetInspector
+            };
        }
    }
 }
@@ -100,6 +100,12 @@ namespace MQTTnet.Implementations

                if (_tcpOptions.TlsOptions?.UseTls == true)
                {
+                    var targetHost = _tcpOptions.TlsOptions.TargetHost;
+                    if (string.IsNullOrEmpty(targetHost))
+                    {
+                        targetHost = _tcpOptions.Server;
+                    }
+                    
                    var sslStream = new SslStream(networkStream, false, InternalUserCertificateValidationCallback);
                    try
                    {
@@ -111,14 +117,16 @@ namespace MQTTnet.Implementations
                            EnabledSslProtocols = _tcpOptions.TlsOptions.SslProtocol,
                            CertificateRevocationCheckMode =
 _tcpOptions.TlsOptions.IgnoreCertificateRevocationErrors ? X509RevocationMode.NoCheck : _tcpOptions.TlsOptions.RevocationMode,
-                            TargetHost = _tcpOptions.Server,
-                            CipherSuitesPolicy = _tcpOptions.TlsOptions.CipherSuitesPolicy
+                            TargetHost = targetHost,
+                            CipherSuitesPolicy = _tcpOptions.TlsOptions.CipherSuitesPolicy,
+                            EncryptionPolicy = _tcpOptions.TlsOptions.EncryptionPolicy,
+                            AllowRenegotiation = _tcpOptions.TlsOptions.AllowRenegotiation
                        };

                        await sslStream.AuthenticateAsClientAsync(sslOptions, cancellationToken).ConfigureAwait(false);
 #else
                        await sslStream.AuthenticateAsClientAsync(
-                                _tcpOptions.Server,
+                                targetHost,
                                LoadCertificates(),
                                _tcpOptions.TlsOptions.SslProtocol,
                                !_tcpOptions.TlsOptions.IgnoreCertificateRevocationErrors)
@@ -290,12 +298,12 @@ namespace MQTTnet.Implementations

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

+            var certificates = new X509CertificateCollection();
            foreach (var certificate in _tcpOptions.TlsOptions.Certificates)
            {
                certificates.Add(certificate);
@@ -95,7 +95,7 @@ namespace MQTTnet.Implementations
                    var packetFormatterAdapter = new MqttPacketFormatterAdapter(bufferWriter);
                    var tcpChannel = new MqttTcpChannel(args.Socket, clientCertificate, _options);

-                    using (var clientAdapter = new MqttChannelAdapter(tcpChannel, packetFormatterAdapter, null, _rootLogger))
+                    using (var clientAdapter = new MqttChannelAdapter(tcpChannel, packetFormatterAdapter, _rootLogger))
                    {
                        await clientHandler(clientAdapter).ConfigureAwait(false);
                    }
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Christian	8ad86928f1	1681 misleading signature of mqttclientconnectasync mqttclientconnectresultcode expected but throws exception (#1749 )	2023-05-29 16:29:16 +02:00
Christian	d8e5936d45	1724 nullreferenceexception on mqttclientconnectasync (#1748 ) Update MqttClient.cs	2023-05-29 13:55:36 +02:00
Christian	caa717544b	1742 some bug in mqttclientconnectionvalidatorhandle (#1746 )	2023-05-29 13:53:42 +02:00
Christian	66b77f8d6d	Merge branch 'master' of https://github.com/dotnet/MQTTnet	2023-05-29 13:47:09 +02:00
Christian	ab5264c8ca	1738 userproperties in clientconnectedeventargs (#1747 )	2023-05-29 13:45:44 +02:00
Christian	db12309bae	Update ReleaseNotes.md	2023-05-29 12:41:28 +02:00
Christian	2953e0dcc5	Improve payload to string conversion	2023-05-29 12:41:24 +02:00
Ramon Smits	1b18ac9fe3	Resolve ConvertPayloadToString resulting in ArgumentNullException (#1745 ) Resolve breaking change where previously ConvertPayloadToString returned null if the payload was null	2023-05-29 12:38:33 +02:00
Christian	2cdad6622a	Fix build	2023-05-14 09:14:37 +02:00
Andrei Kurosh	7601d11a7a	UseDefaultCredentials options for WebSockets proxy configuration. (#1734 )	2023-05-14 08:58:57 +02:00
Christian	0bb4c6ef09	Expose more TLS options (#1737 )	2023-05-13 12:08:52 +02:00
Christian	449624fd72	Expose proper connect result in clients Disconnected event (#1728 )	2023-05-06 12:49:41 +02:00
Christian	99f4f46062	Add new overloads for packet payload and will payload (#1721 )	2023-05-04 22:19:06 +02:00
henry Zeheng Feng Christian	b08d11c069	replace lock/semaphore by readerwriterlockslim to avoid lock contenti… (#1716 ) * replace lock/semaphore by readerwriterlockslim to avoid lock contention while dispatch messages * Update MqttClientSubscriptionsManager.cs removed comment out codes * Update ReleaseNotes.md --------- Co-authored-by: Zeheng Feng <hf944813@broadcom.com> Co-authored-by: Christian <6939810+chkr1011@users.noreply.github.com>	2023-05-01 13:53:15 +02:00
Christian	ac41e838ec	Merge branch 'master' of https://github.com/dotnet/MQTTnet	2023-05-01 12:20:26 +02:00
Christian	836ddf3bbc	Update version	2023-05-01 12:20:20 +02:00
Christian	0e815c626c	Add validation of string lengths (#1718 )	2023-05-01 12:03:23 +02:00
Christian	4b7d035e9e	Reset release notes	2023-04-29 12:37:36 +02:00
Christian	cb3c44f48d	Rename InspectPackage method (#1713 )	2023-04-23 13:57:59 +02:00
Christian	8b3b9d33de	Add overloads for options builder (#1711 ) * Add new overload for options builder * Refactor code * Update ReleaseNotes.md	2023-04-11 22:11:16 +02:00
scottbrogden-iheartmediaandChristian	59d99509c8	Notify what subscription topics failed as part of the SynchronizingSu… (#1678 ) * Notify what subscription topics failed as part of the SynchronizingSubscriptionsFailedAsync callback * Update ReleaseNotes.md --------- Co-authored-by: Christian <6939810+chkr1011@users.noreply.github.com>	2023-04-08 14:03:58 +02:00
RossHNPCandChristian	2933b76237	ClientMessageQueueInterceptor continues with subscription processing. (#1685 ) * ClientMessageQueueInterceptor continues with subscription processing. * Update readme --------- Co-authored-by: Christian <6939810+chkr1011@users.noreply.github.com>	2023-04-06 17:55:33 +02:00
ChristianandMichi	36c6d8974e	Allow disabling of packet fragmentation (#1709 ) * Add compatibility option for AWS * Fix UWP build * Fix comment in MqttClientOptions (#1706) * Refactor naming * Fix wrong option value --------- Co-authored-by: Michi <michael@volz.dev>	2023-04-06 17:54:36 +02:00
Christian	d6cab76728	Add user properties to event args to interceptors for subscribing and unsubscribing (#1707 ) Add user properties to event args	2023-04-06 17:31:42 +02:00
Christian	b4f740f338	Update readme	2023-04-05 22:12:58 +02:00
Christian	a004de25ac	Fix unit test	2023-02-22 21:46:33 +01:00
老九	d0584413ca	Add PayloadSegmentable feature (#1585 )	2023-02-22 20:53:55 +01:00
Christian	ba57537108	Fix running state handling in server (#1680 ) Fix running state handling	2023-02-17 21:17:31 +01:00
Christian	6dcb110737	Add InterceptingClientEnqueueAsync event (#1679 )	2023-02-17 19:13:06 +01:00
Christian	b599a832da	Add new method for reading a single retained message (#1676 )	2023-02-15 19:46:37 +01:00
Christian	9cbd5dd778	Update ReleaseNotes.md	2023-01-28 13:08:24 +01:00
Christian	ed31c51237	Code cleanup	2023-01-28 13:08:21 +01:00
Christian	e01707d25e	Improve samples	2023-01-28 13:08:08 +01:00
Jeffery MichaelandJeff Scherrer	73f118fe1c	Moved the usage of certificate provider into the server listener (#1652 ) * Moved the usage of certificate provider into the server listener so that each connection has the posibility of receiving a new SSL cert. * Removed warning from unused field. * Reduced changeds on original codebase. --------- Co-authored-by: Jeff Scherrer <Jeff.Scherrer@vw.com>	2023-01-28 12:18:31 +01:00
Int32Overflow	0234918f30	Performance impact fix (#1661 )	2023-01-28 12:12:20 +01:00
Jeffery Michael	c90ba7e061	Fixed broken UWP build (#1655 ) Added compiler declaritive to check for WINDOWS_UWP on IsAssignableFrom call.	2023-01-28 12:02:22 +01:00