Refactor namings of serializers etc.

Source/MQTTnet.AspnetCore/Client/MqttClientConnectionContextFactory.cs

@@ -4,7 +4,7 @@ using MQTTnet.Adapter;
 using MQTTnet.AspNetCore.Client.Tcp;
 using MQTTnet.Client;
 using MQTTnet.Diagnostics;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.AspNetCore.Client
 {

Source/MQTTnet.AspnetCore/MqttConnectionContext.cs

@@ -3,11 +3,11 @@ using MQTTnet.Adapter;
 using MQTTnet.AspNetCore.Client.Tcp;
 using MQTTnet.Exceptions;
 using MQTTnet.Packets;
-using MQTTnet.Serializer;
 using System;
 using System.IO.Pipelines;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.AspNetCore
 {
@@ -72,7 +72,7 @@ namespace MQTTnet.AspNetCore
                     {
                         if (!buffer.IsEmpty)
                         {
-                            if (PacketSerializerAdapter.Serializer.TryDeserialize(buffer, out var packet, out consumed, out observed))
+                            if (PacketSerializerAdapter.Formatter.TryDeserialize(buffer, out var packet, out consumed, out observed))
                             {
                                 return packet;
                             }
@@ -107,7 +107,7 @@ namespace MQTTnet.AspNetCore
 
         public async Task SendPacketAsync(MqttBasePacket packet, CancellationToken cancellationToken)
         {
-            var buffer = PacketSerializerAdapter.Serialize(packet).AsMemory();
+            var buffer = PacketSerializerAdapter.Encode(packet).AsMemory();
             var output = Connection.Transport.Output;
 
             await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);

Source/MQTTnet.AspnetCore/MqttConnectionHandler.cs

@@ -1,10 +1,10 @@
 using Microsoft.AspNetCore.Connections;
 using Microsoft.AspNetCore.Connections.Features;
 using MQTTnet.Adapter;
-using MQTTnet.Serializer;
 using MQTTnet.Server;
 using System;
 using System.Threading.Tasks;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.AspNetCore
 {

Source/MQTTnet.AspnetCore/MqttWebSocketServerAdapter.cs

@@ -3,8 +3,8 @@ using System.Net.WebSockets;
 using System.Threading.Tasks;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
+using MQTTnet.Formatter;
 using MQTTnet.Implementations;
-using MQTTnet.Serializer;
 using MQTTnet.Server;
 
 namespace MQTTnet.AspNetCore

Source/MQTTnet.AspnetCore/ReaderExtensions.cs

@@ -2,15 +2,17 @@
 using System.Buffers;
 using MQTTnet.Adapter;
 using MQTTnet.Exceptions;
+using MQTTnet.Formatter;
 using MQTTnet.Packets;
-using MQTTnet.Serializer;
 
 namespace MQTTnet.AspNetCore
 {
     public static class ReaderExtensions
     {
-        public static bool TryDeserialize(this IMqttPacketSerializer serializer, in ReadOnlySequence<byte> input, out MqttBasePacket packet, out SequencePosition consumed, out SequencePosition observed)
+        public static bool TryDeserialize(this IMqttPacketFormatter formatter, in ReadOnlySequence<byte> input, out MqttBasePacket packet, out SequencePosition consumed, out SequencePosition observed)
         {
+            if (formatter == null) throw new ArgumentNullException(nameof(formatter));
+
             packet = null;
             consumed = input.Start;
             observed = input.End;
@@ -33,7 +35,7 @@ namespace MQTTnet.AspNetCore
 
             var bodySlice = copy.Slice(0, bodyLength);
             var buffer = bodySlice.GetArray();
-            packet = serializer.Deserialize(new ReceivedMqttPacket(fixedheader, new MqttPacketBodyReader(buffer, 0, buffer.Length)));
+            packet = formatter.Decode(new ReceivedMqttPacket(fixedheader, new MqttPacketBodyReader(buffer, 0, buffer.Length)));
             consumed = bodySlice.End;
             observed = bodySlice.End;
             return true;

Source/MQTTnet/Adapter/IMqttChannelAdapter.cs

@@ -1,8 +1,8 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Formatter;
 using MQTTnet.Packets;
-using MQTTnet.Serializer;
 
 namespace MQTTnet.Adapter
 {

Source/MQTTnet/Adapter/MqttChannelAdapter.cs

@@ -7,9 +7,9 @@ using System.Threading.Tasks;
 using MQTTnet.Channel;
 using MQTTnet.Diagnostics;
 using MQTTnet.Exceptions;
+using MQTTnet.Formatter;
 using MQTTnet.Internal;
 using MQTTnet.Packets;
-using MQTTnet.Serializer;
 
 namespace MQTTnet.Adapter
 {
@@ -96,7 +96,7 @@ namespace MQTTnet.Adapter
             await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
             try
             {
-                var packetData = PacketSerializerAdapter.Serialize(packet);
+                var packetData = PacketSerializerAdapter.Encode(packet);
                 await _channel.WriteAsync(packetData.Array, packetData.Offset, packetData.Count, cancellationToken).ConfigureAwait(false);
                 PacketSerializerAdapter.FreeBuffer();
 
@@ -144,7 +144,7 @@ namespace MQTTnet.Adapter
                     PacketSerializerAdapter.DetectProtocolVersion(receivedMqttPacket);
                 }
 
-                var packet = PacketSerializerAdapter.Deserialize(receivedMqttPacket);
+                var packet = PacketSerializerAdapter.Decode(receivedMqttPacket);
                 if (packet == null)
                 {
                     throw new MqttProtocolViolationException("Received malformed packet.");

Source/MQTTnet/Adapter/ReceivedMqttPacket.cs

@@ -1,4 +1,4 @@
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Adapter
 {

Source/MQTTnet/Client/IMqttClientOptions.cs

@@ -1,5 +1,5 @@
 using System;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Client
 {

Source/MQTTnet/Client/MqttClientOptions.cs

@@ -1,5 +1,5 @@
 using System;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Client
 {

Source/MQTTnet/Client/MqttClientOptionsBuilder.cs

@@ -1,6 +1,6 @@
 using System;
 using System.Linq;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Client
 {

Source/MQTTnet/Formatter/IMqttPacketFormatter.cs

@@ -0,0 +1,15 @@
+using System;
+using MQTTnet.Adapter;
+using MQTTnet.Packets;
+
+namespace MQTTnet.Formatter
+{
+    public interface IMqttPacketFormatter
+    {
+        ArraySegment<byte> Encode(MqttBasePacket mqttPacket);
+
+        MqttBasePacket Decode(ReceivedMqttPacket receivedMqttPacket);
+
+        void FreeBuffer();
+    }
+}

Source/MQTTnet/Formatter/MqttFixedHeader.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Serializer
+namespace MQTTnet.Formatter
 {
     public struct MqttFixedHeader
     {

Source/MQTTnet/Formatter/MqttPacketBodyReader.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Text;
 
-namespace MQTTnet.Serializer
+namespace MQTTnet.Formatter
 {
     public class MqttPacketBodyReader
     {

Source/MQTTnet/Formatter/MqttPacketReader.cs

@@ -4,7 +4,7 @@ using MQTTnet.Channel;
 using MQTTnet.Exceptions;
 using MQTTnet.Internal;
 
-namespace MQTTnet.Serializer
+namespace MQTTnet.Formatter
 {
     public static class MqttPacketReader
     {

Source/MQTTnet/Formatter/MqttPacketSerializerAdapter.cs

@@ -1,9 +1,12 @@
 using System;
 using MQTTnet.Adapter;
 using MQTTnet.Exceptions;
+using MQTTnet.Formatter.V310;
+using MQTTnet.Formatter.V311;
+using MQTTnet.Formatter.V500;
 using MQTTnet.Packets;
 
-namespace MQTTnet.Serializer
+namespace MQTTnet.Formatter
 {
     public class MqttPacketSerializerAdapter
     {
@@ -18,31 +21,31 @@ namespace MQTTnet.Serializer
 
         public MqttProtocolVersion? ProtocolVersion { get; private set; }
 
-        public IMqttPacketSerializer Serializer { get; private set; }
+        public IMqttPacketFormatter Formatter { get; private set; }
 
-        public ArraySegment<byte> Serialize(MqttBasePacket packet)
+        public ArraySegment<byte> Encode(MqttBasePacket packet)
         {
-            if (Serializer == null)
+            if (Formatter == null)
             {
                 throw new InvalidOperationException("Protocol version not set or detected.");
             }
 
-            return Serializer.Serialize(packet);
+            return Formatter.Encode(packet);
         }
 
-        public MqttBasePacket Deserialize(ReceivedMqttPacket receivedMqttPacket)
+        public MqttBasePacket Decode(ReceivedMqttPacket receivedMqttPacket)
         {
-            if (Serializer == null)
+            if (Formatter == null)
             {
                 throw new InvalidOperationException("Protocol version not set or detected.");
             }
 
-            return Serializer.Deserialize(receivedMqttPacket);
+            return Formatter.Decode(receivedMqttPacket);
         }
 
         public void FreeBuffer()
         {
-            Serializer?.FreeBuffer();
+            Formatter?.FreeBuffer();
         }
 
         public void DetectProtocolVersion(ReceivedMqttPacket receivedMqttPacket)
@@ -65,20 +68,20 @@ namespace MQTTnet.Serializer
             {
                 case MqttProtocolVersion.V500:
                     {
-                        Serializer = new MqttV500PacketSerializer();
+                        Formatter = new MqttV500PacketFormatter();
                         break;
                     }
 
                 case MqttProtocolVersion.V311:
                     {
-                        Serializer = new MqttV311PacketSerializer();
+                        Formatter = new MqttV311PacketFormatter();
                         break;
                     }
 
                 case MqttProtocolVersion.V310:
                     {
 
-                        Serializer = new MqttV310PacketSerializer();
+                        Formatter = new MqttV310PacketFormatter();
                         break;
                     }
                     

Source/MQTTnet/Formatter/MqttPacketWriter.cs

@@ -3,7 +3,7 @@ using System.Runtime.CompilerServices;
 using System.Text;
 using MQTTnet.Protocol;
 
-namespace MQTTnet.Serializer
+namespace MQTTnet.Formatter
 {
     /// <summary>
     /// This is a custom implementation of a memory stream which provides only MQTTnet relevant features.

Source/MQTTnet/Formatter/MqttProtocolVersion.cs

@@ -1,4 +1,4 @@
-namespace MQTTnet.Serializer
+namespace MQTTnet.Formatter
 {
     public enum MqttProtocolVersion
     {

Source/MQTTnet/Formatter/V310/MqttV310PacketFormatter.cs

@@ -1,19 +1,20 @@
-using MQTTnet.Exceptions;
-using MQTTnet.Packets;
-using MQTTnet.Protocol;
-using System;
+using System;
 using System.Linq;
 using MQTTnet.Adapter;
+using MQTTnet.Exceptions;
+using MQTTnet.Internal;
+using MQTTnet.Packets;
+using MQTTnet.Protocol;
 
-namespace MQTTnet.Serializer
+namespace MQTTnet.Formatter.V310
 {
-    public class MqttV310PacketSerializer : IMqttPacketSerializer
+    public class MqttV310PacketFormatter : IMqttPacketFormatter
     {
         private const int FixedHeaderSize = 1;
 
         private readonly MqttPacketWriter _packetWriter = new MqttPacketWriter();
 
-        public ArraySegment<byte> Serialize(MqttBasePacket packet)
+        public ArraySegment<byte> Encode(MqttBasePacket packet)
         {
             if (packet == null) throw new ArgumentNullException(nameof(packet));
 
@@ -38,7 +39,7 @@ namespace MQTTnet.Serializer
             return new ArraySegment<byte>(buffer, headerOffset, _packetWriter.Length - headerOffset);
         }
 
-        public MqttBasePacket Deserialize(ReceivedMqttPacket receivedMqttPacket)
+        public MqttBasePacket Decode(ReceivedMqttPacket receivedMqttPacket)
         {
             if (receivedMqttPacket == null) throw new ArgumentNullException(nameof(receivedMqttPacket));
 
@@ -300,11 +301,6 @@ namespace MQTTnet.Serializer
             {
                 throw new MqttProtocolViolationException("CleanSession must be set if ClientId is empty [MQTT-3.1.3-7].");
             }
-
-            if (packet.Properties != null)
-            {
-                throw new MqttProtocolViolationException("Properties are only supported in MQTT Version 5.");
-            }
         }
 
         // ReSharper disable once ParameterOnlyUsedForPreconditionCheck.Local

Source/MQTTnet/Formatter/V311/MqttV311PacketFormatter.cs

@@ -1,10 +1,11 @@
 using MQTTnet.Exceptions;
+using MQTTnet.Formatter.V310;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
 
-namespace MQTTnet.Serializer
+namespace MQTTnet.Formatter.V311
 {
-    public class MqttV311PacketSerializer : MqttV310PacketSerializer
+    public class MqttV311PacketFormatter : MqttV310PacketFormatter
     {
         protected override byte SerializeConnectPacket(MqttConnectPacket packet, MqttPacketWriter packetWriter)
         {

Source/MQTTnet/Formatter/V500/MqttV500PacketDecoder.cs

@@ -0,0 +1,6 @@
+namespace MQTTnet.Formatter.V500
+{
+    public class MqttV500PacketDecoder
+    {
+    }
+}

Source/MQTTnet/Formatter/V500/MqttV500PacketEncoder.cs

@@ -0,0 +1,6 @@
+namespace MQTTnet.Formatter.V500
+{
+    public class MqttV500PacketEncoder
+    {
+    }
+}

Source/MQTTnet/Formatter/V500/MqttV500PacketFormatter.cs

@@ -0,0 +1,187 @@
+using System;
+using System.Collections.Generic;
+using MQTTnet.Exceptions;
+using MQTTnet.Formatter.V311;
+using MQTTnet.Packets;
+using MQTTnet.Packets.Properties;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Formatter.V500
+{
+    public class MqttV500PacketFormatter : MqttV311PacketFormatter
+    {
+        private readonly MqttV500PacketEncoder _encoder = new MqttV500PacketEncoder();
+        private readonly MqttV500PacketDecoder _decoder = new MqttV500PacketDecoder();
+
+        protected override byte SerializeConnectPacket(MqttConnectPacket packet, MqttPacketWriter packetWriter)
+        {
+            ValidateConnectPacket(packet);
+
+            packetWriter.WriteWithLengthPrefix("MQTT");
+            packetWriter.Write(5); // [3.1.2.2 Protocol Version]
+
+            byte connectFlags = 0x0;
+            if (packet.CleanSession)
+            {
+                connectFlags |= 0x2;
+            }
+
+            if (packet.WillMessage != null)
+            {
+                connectFlags |= 0x4;
+                connectFlags |= (byte)((byte)packet.WillMessage.QualityOfServiceLevel << 3);
+
+                if (packet.WillMessage.Retain)
+                {
+                    connectFlags |= 0x20;
+                }
+            }
+
+            if (packet.Password != null && packet.Username == null)
+            {
+                throw new MqttProtocolViolationException("If the User Name Flag is set to 0, the Password Flag MUST be set to 0 [MQTT-3.1.2-22].");
+            }
+
+            if (packet.Password != null)
+            {
+                connectFlags |= 0x40;
+            }
+
+            if (packet.Username != null)
+            {
+                connectFlags |= 0x80;
+            }
+
+            packetWriter.Write(connectFlags);
+            packetWriter.Write(packet.KeepAlivePeriod);
+            packetWriter.WriteWithLengthPrefix(packet.ClientId);
+
+            if (packet.WillMessage != null)
+            {
+                packetWriter.WriteWithLengthPrefix(packet.WillMessage.Topic);
+                packetWriter.WriteWithLengthPrefix(packet.WillMessage.Payload);
+            }
+
+            if (packet.Username != null)
+            {
+                packetWriter.WriteWithLengthPrefix(packet.Username);
+            }
+
+            if (packet.Password != null)
+            {
+                packetWriter.WriteWithLengthPrefix(packet.Password);
+            }
+
+            WriteProperty(MqttMessagePropertyID.WillDelayInterval, packet.WillDelayIntervalProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.SessionExpiryInterval, packet.SessionExpiryIntervalProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.AuthenticationMethod, packet.AuthenticationMethodProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.AuthenticationData, packet.AuthenticationDataProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.RequestProblemInformation, packet.RequestProblemInformationProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.RequestResponseInformation, packet.RequestResponseInformationProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.ReceiveMaximum, packet.ReceiveMaximumProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.TopicAlias, packet.TopicAliasMaximumProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.MaximumPacketSize, packet.MaximumPacketSizeProperty, packetWriter);
+            WriteUserProperties(packet.UserPropertiesProperty, packetWriter);
+
+            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Connect);
+        }
+
+        protected override byte SerializeConnAckPacket(MqttConnAckPacket packet, MqttPacketWriter packetWriter)
+        {
+            byte connectAcknowledgeFlags = 0x0;
+            if (packet.IsSessionPresent)
+            {
+                connectAcknowledgeFlags |= 0x1;
+            }
+
+            packetWriter.Write(connectAcknowledgeFlags);
+            packetWriter.Write((byte)packet.ConnectReturnCode);
+
+            WriteProperty(MqttMessagePropertyID.SessionExpiryInterval, packet.SessionExpiryIntervalProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.AuthenticationMethod, packet.AuthenticationMethodProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.AuthenticationData, packet.AuthenticationDataProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.ReceiveMaximum, packet.ReceiveMaximumProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.TopicAlias, packet.TopicAliasMaximumProperty, packetWriter);
+            WriteProperty(MqttMessagePropertyID.MaximumPacketSize, packet.MaximumPacketSizeProperty, packetWriter);
+            WriteUserProperties(packet.UserPropertiesProperty, packetWriter);
+
+            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.ConnAck);
+        }
+
+        private static void WriteProperty(MqttMessagePropertyID id, bool? value, MqttPacketWriter target)
+        {
+            if (!value.HasValue)
+            {
+                return;
+            }
+
+            target.Write((byte)id);
+            target.Write(value.Value ? (byte)0x1 : (byte)0x0);
+        }
+
+        private static void WriteProperty(MqttMessagePropertyID id, ushort? value, MqttPacketWriter target)
+        {
+            if (!value.HasValue)
+            {
+                return;
+            }
+
+            target.Write((byte)id);
+            target.Write(value.Value);
+        }
+
+        private static void WriteProperty(MqttMessagePropertyID id, uint? value, MqttPacketWriter target)
+        {
+            if (!value.HasValue)
+            {
+                return;
+            }
+
+            // TODO: Check if order must be reversed like for ushort.
+            target.Write((byte)id);
+            var bytes = BitConverter.GetBytes(value.Value);
+            target.Write(bytes, 0, bytes.Length);
+        }
+
+        private static void WriteProperty(MqttMessagePropertyID id, string value, MqttPacketWriter target)
+        {
+            if (value == null)
+            {
+                return;
+            }
+            
+            target.Write((byte)id);
+            target.WriteWithLengthPrefix(value);
+        }
+
+        private static void WriteProperty(MqttMessagePropertyID id, byte[] value, MqttPacketWriter target)
+        {
+            if (value == null)
+            {
+                return;
+            }
+
+            target.Write((byte)id);
+            target.WriteWithLengthPrefix(value);
+        }
+
+        private static void WriteUserProperties(List<MqttUserProperty> userProperties, MqttPacketWriter target)
+        {
+            if (userProperties == null || userProperties.Count == 0)
+            {
+                return;
+            }
+
+            var propertyWriter = new MqttPacketWriter();
+            foreach (var property in userProperties)
+            {
+                propertyWriter.WriteWithLengthPrefix(property.Name);
+                propertyWriter.WriteWithLengthPrefix(property.Value);
+            }
+
+            target.Write((byte)MqttMessagePropertyID.UserProperty);
+            target.WriteVariableLengthInteger((uint)propertyWriter.Length);
+            target.Write(propertyWriter);
+        }
+    }
+}

Source/MQTTnet/Implementations/MqttClientAdapterFactory.cs

@@ -2,7 +2,7 @@
 using MQTTnet.Adapter;
 using MQTTnet.Client;
 using MQTTnet.Diagnostics;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Implementations
 {

Source/MQTTnet/Implementations/MqttTcpServerAdapter.Uwp.cs

@@ -4,7 +4,7 @@ using System.Threading.Tasks;
 using Windows.Networking.Sockets;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 using MQTTnet.Server;
 
 namespace MQTTnet.Implementations

Source/MQTTnet/Implementations/MqttTcpServerListener.cs

@@ -9,7 +9,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 using MQTTnet.Server;
 
 namespace MQTTnet.Implementations

Source/MQTTnet/Internal/ArraySegmentExtensions.cs

@@ -1,8 +1,8 @@
 using System;
 
-namespace MQTTnet.Serializer
+namespace MQTTnet.Internal
 {
-    public static class Extensions
+    public static class ArraySegmentExtensions
     {
         public static byte[] ToArray(this ArraySegment<byte> source)
         {

Source/MQTTnet/MQTTnet.csproj

@@ -69,4 +69,10 @@
     <None Remove="NewFolder\**" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Reference Include="System.Net.Requests">
+      <HintPath>C:\Program Files\dotnet\sdk\NuGetFallbackFolder\microsoft.netcore.app\2.1.0\ref\netcoreapp2.1\System.Net.Requests.dll</HintPath>
+    </Reference>
+  </ItemGroup>
+
 </Project>

Source/MQTTnet/Packets/MqttAuthPacket.cs

@@ -0,0 +1,16 @@
+using System.Collections.Generic;
+using MQTTnet.Packets.Properties;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Packets
+{
+    /// <summary>
+    /// Added in MQTTv5.0.0.
+    /// </summary>
+    public class MqttAuthPacket : MqttBasePacket
+    {
+        public MqttAuthenticateReasonCode ReasonCode { get; set; }
+
+        public List<IProperty> Properties { get; set; }
+    }
+}

Source/MQTTnet/Packets/MqttBasePublishPacket.cs

@@ -1,7 +1,15 @@
-namespace MQTTnet.Packets
+using System.Collections.Generic;
+using MQTTnet.Packets.Properties;
+
+namespace MQTTnet.Packets
 {
     public class MqttBasePublishPacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
         public ushort? PacketIdentifier { get; set; }
+
+        /// <summary>
+        /// Added in MQTTv5.0.0.
+        /// </summary>
+        public List<IProperty> Properties { get; set; }
     }
 }

Source/MQTTnet/Packets/MqttConnAckPacket.cs

@@ -1,15 +1,53 @@
-using MQTTnet.Protocol;
+using System.Collections.Generic;
+using MQTTnet.Protocol;
 
 namespace MQTTnet.Packets
 {
     public class MqttConnAckPacket : MqttBasePacket
     {
+        public MqttConnectReturnCode ConnectReturnCode { get; set; }
+
         /// <summary>
         /// Added in MQTTv3.1.1.
         /// </summary>
         public bool IsSessionPresent { get; set; }
 
-        public MqttConnectReturnCode ConnectReturnCode { get; set; }
+        #region Added in MQTTv5
+
+        public uint? SessionExpiryIntervalProperty { get; set; }
+
+        // TODO: Add enum
+        public byte? ReceiveMaximumProperty { get; set; }
+
+        public bool? RetainAvailableProperty { get; set; }
+
+        public uint? MaximumPacketSizeProperty { get; set; }
+
+        public string AssignedClientIdentifierProperty { get; set; }
+
+        public ushort? TopicAliasMaximumProperty { get; set; }
+
+        public string ReasonStringProperty { get; set; }
+
+        public List<MqttUserProperty> UserPropertiesProperty { get; set; }
+
+        public bool? WildcardSubscriptionAvailableProperty { get; set; }
+
+        public bool? SubscriptionIdentifiersAvailableProperty { get; set; }
+
+        public bool? SharedSubscriptionAvailableProperty { get; set; }
+
+        public ushort? ServerKeepAliveProperty { get; set; }
+
+        public string ResponseInformationProperty { get; set; }
+
+        public string ServerReferenceProperty { get; set; }
+
+        public string AuthenticationMethodProperty { get; set; }
+
+        public byte[] AuthenticationDataProperty { get; set; }
+
+        #endregion
 
         public override string ToString()
         {

Source/MQTTnet/Packets/MqttConnectPacket.cs

@@ -1,5 +1,4 @@
 using System.Collections.Generic;
-using MQTTnet.Packets.Properties;
 
 namespace MQTTnet.Packets
 {
@@ -24,7 +23,29 @@ namespace MQTTnet.Packets
 
         public MqttApplicationMessage WillMessage { get; set; }
 
-        public List<IProperty> Properties { get; set; }
+        #region Added in MQTTv5
+
+        public uint? WillDelayIntervalProperty { get; set; }
+
+        public uint? SessionExpiryIntervalProperty { get; set; }
+
+        public string AuthenticationMethodProperty { get; set; }
+
+        public byte[] AuthenticationDataProperty { get; set; }
+
+        public bool? RequestProblemInformationProperty { get; set; }
+
+        public bool? RequestResponseInformationProperty { get; set; }
+
+        public ushort? ReceiveMaximumProperty { get; set; }
+
+        public ushort? TopicAliasMaximumProperty { get; set; }
+
+        public uint? MaximumPacketSizeProperty { get; set; }
+
+        public List<MqttUserProperty> UserPropertiesProperty { get; set; }
+
+        #endregion
 
         public override string ToString()
         {

Source/MQTTnet/Packets/MqttDisconnectPacket.cs

@@ -1,7 +1,15 @@
-namespace MQTTnet.Packets
+using System.Collections.Generic;
+using MQTTnet.Packets.Properties;
+
+namespace MQTTnet.Packets
 {
     public class MqttDisconnectPacket : MqttBasePacket
     {
+        /// <summary>
+        /// Added in MQTTv5.0.0.
+        /// </summary>
+        public List<IProperty> Properties { get; set; }
+
         public override string ToString()
         {
             return "Disconnect";

Source/MQTTnet/Packets/MqttPublishPacket.cs

@@ -1,4 +1,6 @@
-using MQTTnet.Protocol;
+using System.Collections.Generic;
+using MQTTnet.Packets.Properties;
+using MQTTnet.Protocol;
 
 namespace MQTTnet.Packets
 {
@@ -14,6 +16,11 @@ namespace MQTTnet.Packets
 
         public byte[] Payload { get; set; }
 
+        /// <summary>
+        /// Added in MQTTv5.0.0.
+        /// </summary>
+        public List<IProperty> Properties { get; set; }
+
         public override string ToString()
         {
             return "Publish: [Topic=" + Topic + "]" +

Source/MQTTnet/Packets/MqttSubscribePacket.cs

@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using System.Linq;
+using MQTTnet.Packets.Properties;
 
 namespace MQTTnet.Packets
 {
@@ -9,6 +10,11 @@ namespace MQTTnet.Packets
 
         public IList<TopicFilter> TopicFilters { get; set; } = new List<TopicFilter>();
 
+        /// <summary>
+        /// Added in MQTTv5.0.0.
+        /// </summary>
+        public List<IProperty> Properties { get; set; }
+
         public override string ToString()
         {
             var topicFiltersText = string.Join(",", TopicFilters.Select(f => f.Topic + "@" + f.QualityOfServiceLevel));

Source/MQTTnet/Packets/MqttUserProperty.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace MQTTnet.Packets
+{
+    public class MqttUserProperty
+    {
+        public MqttUserProperty(string name, string value)
+        {
+            Name = name ?? throw new ArgumentNullException(nameof(name));
+            Value = value ?? throw new ArgumentNullException(nameof(value));
+        }
+
+        public string Name { get; }
+
+        public string Value { get; }
+    }
+}

Source/MQTTnet/Packets/Properties/AssignedClientIdentifierProperty.cs

@@ -1,9 +1,11 @@
-namespace MQTTnet.Packets.Properties
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
 {
     public class AssignedClientIdentifierProperty : StringProperty
     {
         public AssignedClientIdentifierProperty(string value) 
-            : base((byte)PropertyID.AssignedClientIdentifer, value)
+            : base((byte)MqttMessagePropertyID.AssignedClientIdentifer, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/AuthenticationDataProperty.cs

@@ -1,11 +1,12 @@
 using System;
+using MQTTnet.Packets.Properties.BaseTypes;
 
 namespace MQTTnet.Packets.Properties
 {
     public class AuthenticationDataProperty : BinaryDataProperty
     {
         public AuthenticationDataProperty(ArraySegment<byte> data) 
-            : base((byte)PropertyID.AuthenticationData, data)
+            : base((byte)MqttMessagePropertyID.AuthenticationData, data)
         {
         }
     }

Source/MQTTnet/Packets/Properties/AuthenticationMethodProperty.cs

@@ -1,9 +1,11 @@
-namespace MQTTnet.Packets.Properties
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
 {
     public class AuthenticationMethodProperty : StringProperty
     {
         public AuthenticationMethodProperty(string value) 
-            : base((byte)PropertyID.AuthenticationMethod, value)
+            : base((byte)MqttMessagePropertyID.AuthenticationMethod, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/BaseTypes/BinaryDataProperty.cs

@@ -1,7 +1,7 @@
 using System;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
-namespace MQTTnet.Packets.Properties
+namespace MQTTnet.Packets.Properties.BaseTypes
 {
     public class BinaryDataProperty : IProperty
     {
@@ -24,6 +24,7 @@ namespace MQTTnet.Packets.Properties
         {
             if (writer == null) throw new ArgumentNullException(nameof(writer));
 
+            writer.Write(Id);
             writer.Write((ushort)Data.Count);
             writer.Write(Data);
         }

Source/MQTTnet/Packets/Properties/BaseTypes/ByteProperty.cs

@@ -1,7 +1,7 @@
 using System;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
-namespace MQTTnet.Packets.Properties
+namespace MQTTnet.Packets.Properties.BaseTypes
 {
     public class ByteProperty : IProperty
     {
@@ -18,7 +18,8 @@ namespace MQTTnet.Packets.Properties
         public void WriteTo(MqttPacketWriter writer)
         {
             if (writer == null) throw new ArgumentNullException(nameof(writer));
-            
+
+            writer.Write(Id);
             writer.Write(Value);
         }
     }

Source/MQTTnet/Packets/Properties/BaseTypes/FourByteIntegerProperty.cs

@@ -1,5 +1,5 @@
 using System;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Packets.Properties.BaseTypes
 {
@@ -20,6 +20,7 @@ namespace MQTTnet.Packets.Properties.BaseTypes
             if (writer == null) throw new ArgumentNullException(nameof(writer));
 
             // TODO: Check if order must be reversed like for ushort.
+            writer.Write(Id);
             var bytes = BitConverter.GetBytes(Value);
             writer.Write(bytes, 0, bytes.Length);
         }

Source/MQTTnet/Packets/Properties/BaseTypes/StringProperty.cs

@@ -1,7 +1,7 @@
 using System;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
-namespace MQTTnet.Packets.Properties
+namespace MQTTnet.Packets.Properties.BaseTypes
 {
     public class StringProperty : IProperty
     {
@@ -19,6 +19,7 @@ namespace MQTTnet.Packets.Properties
         {
             if (writer == null) throw new ArgumentNullException(nameof(writer));
 
+            writer.Write(Id);
             writer.WriteWithLengthPrefix(Value);
         }
     }

Source/MQTTnet/Packets/Properties/BaseTypes/TwoByteIntegerProperty.cs

@@ -1,5 +1,5 @@
 using System;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Packets.Properties.BaseTypes
 {
@@ -19,6 +19,7 @@ namespace MQTTnet.Packets.Properties.BaseTypes
         {
             if (writer == null) throw new ArgumentNullException(nameof(writer));
 
+            writer.Write(Id);
             writer.Write(Value);
         }
     }

Source/MQTTnet/Packets/Properties/BaseTypes/VariableByteIntegerProperty.cs

@@ -1,5 +1,5 @@
 using System;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Packets.Properties.BaseTypes
 {
@@ -20,6 +20,8 @@ namespace MQTTnet.Packets.Properties.BaseTypes
             if (writer == null) throw new ArgumentNullException(nameof(writer));
 
             var buffer = MqttPacketWriter.EncodeVariableByteInteger(Value);
+
+            writer.Write(Id);
             writer.Write(buffer);
         }
     }

Source/MQTTnet/Packets/Properties/ContentTypeProperty.cs

@@ -1,9 +1,11 @@
-namespace MQTTnet.Packets.Properties
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
 {
     public class ContentTypeProperty : StringProperty
     {
         public ContentTypeProperty(string value) 
-            : base((byte)PropertyID.ContentType, value)
+            : base((byte)MqttMessagePropertyID.ContentType, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/CorrelationDataProperty.cs

@@ -1,11 +1,12 @@
 using System;
+using MQTTnet.Packets.Properties.BaseTypes;
 
 namespace MQTTnet.Packets.Properties
 {
     public class CorrelationDataProperty : BinaryDataProperty
     {
         public CorrelationDataProperty(ArraySegment<byte> data) 
-            : base((byte)PropertyID.CorrelationData, data)
+            : base((byte)MqttMessagePropertyID.CorrelationData, data)
         {
         }
     }

Source/MQTTnet/Packets/Properties/IProperty.cs

@@ -1,4 +1,4 @@
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Packets.Properties
 {

Source/MQTTnet/Packets/Properties/MaximumPacketSizeProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class MaximumPacketSizeProperty : FourByteIntegerValue
+    {
+        public MaximumPacketSizeProperty(uint value) 
+            : base((byte)MqttMessagePropertyID.MaximumPacketSize, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/MaximumQoSProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class MaximumQoSProperty : ByteProperty
+    {
+        public MaximumQoSProperty(byte value) 
+            : base((byte)MqttMessagePropertyID.MaximumQoS, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/MessageExpiryIntervalProperty.cs

@@ -5,7 +5,7 @@ namespace MQTTnet.Packets.Properties
     public class MessageExpiryIntervalProperty : FourByteIntegerValue
     {
         public MessageExpiryIntervalProperty(uint value) 
-            : base((byte)PropertyID.MessageExpiryInterval, value)
+            : base((byte)MqttMessagePropertyID.MessageExpiryInterval, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/MqttMessagePropertyID.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Packets.Properties
 {
-    public enum PropertyID
+    public enum MqttMessagePropertyID
     {
         PayloadFormatIndicator = 1,
         MessageExpiryInterval = 2,

Source/MQTTnet/Packets/Properties/PayloadFormatIndicatorProperty.cs

@@ -1,9 +1,11 @@
-namespace MQTTnet.Packets.Properties
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
 {
     public class PayloadFormatIndicatorProperty : ByteProperty
     {
         public PayloadFormatIndicatorProperty(byte value) 
-            : base((byte)PropertyID.PayloadFormatIndicator, value)
+            : base((byte)MqttMessagePropertyID.PayloadFormatIndicator, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/ReasonStringProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class ReasonStringProperty : StringProperty
+    {
+        public ReasonStringProperty(string value) 
+            : base((byte)MqttMessagePropertyID.ReasonString, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/ReceiveMaximumProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class ReceiveMaximumProperty : TwoByteIntegerProperty
+    {
+        public ReceiveMaximumProperty(ushort value) 
+            : base((byte)MqttMessagePropertyID.ReceiveMaximum, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/RequestProblemInformationProperty.cs

@@ -1,9 +1,11 @@
-namespace MQTTnet.Packets.Properties
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
 {
     public class RequestProblemInformationProperty : ByteProperty
     {
         public RequestProblemInformationProperty(byte value) 
-            : base((byte)PropertyID.RequestProblemInformation, value)
+            : base((byte)MqttMessagePropertyID.RequestProblemInformation, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/RequestResponseInformationProperty.cs

@@ -1,9 +1,11 @@
-namespace MQTTnet.Packets.Properties
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
 {
     public class RequestResponseInformationProperty : ByteProperty
     {
         public RequestResponseInformationProperty(byte value) 
-            : base((byte)PropertyID.RequestResponseInformation, value)
+            : base((byte)MqttMessagePropertyID.RequestResponseInformation, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/ResponseInformationProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class ResponseInformationProperty : StringProperty
+    {
+        public ResponseInformationProperty(string value) 
+            : base((byte)MqttMessagePropertyID.ResponseInformation, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/ResponseTopicProperty.cs

@@ -1,9 +1,11 @@
-namespace MQTTnet.Packets.Properties
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
 {
     public class ResponseTopicProperty : StringProperty
     {
         public ResponseTopicProperty(string value) 
-            : base((byte)PropertyID.ResponseTopic, value)
+            : base((byte)MqttMessagePropertyID.ResponseTopic, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/RetainAvailableProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class RetainAvailableProperty : ByteProperty
+    {
+        public RetainAvailableProperty(byte value) 
+            : base((byte)MqttMessagePropertyID.RetainAvailable, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/ServerKeepAliveProperty.cs

@@ -5,7 +5,7 @@ namespace MQTTnet.Packets.Properties
     public class ServerKeepAliveProperty : TwoByteIntegerProperty
     {
         public ServerKeepAliveProperty(ushort value) 
-            : base((byte)PropertyID.ServerKeepAlive, value)
+            : base((byte)MqttMessagePropertyID.ServerKeepAlive, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/ServerReferenceProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class ServerReferenceProperty : StringProperty
+    {
+        public ServerReferenceProperty(string value) 
+            : base((byte)MqttMessagePropertyID.ServerReference, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/SessionExpiryIntervalProperty.cs

@@ -5,7 +5,7 @@ namespace MQTTnet.Packets.Properties
     public class SessionExpiryIntervalProperty : FourByteIntegerValue
     {
         public SessionExpiryIntervalProperty(uint value) 
-            : base((byte)PropertyID.SessionExpiryInterval, value)
+            : base((byte)MqttMessagePropertyID.SessionExpiryInterval, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/SharedSubscriptionAvailableProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class SharedSubscriptionAvailableProperty : ByteProperty
+    {
+        public SharedSubscriptionAvailableProperty(byte value) 
+            : base((byte)MqttMessagePropertyID.SharedSubscriptionAvailable, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/SubscriptionIdentifierAvailable.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class SubscriptionIdentifierAvailable : ByteProperty
+    {
+        public SubscriptionIdentifierAvailable(byte value) 
+            : base((byte)MqttMessagePropertyID.SubscriptionIdentifierAvailable, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/SubscriptionIdentifierProperty.cs

@@ -5,7 +5,7 @@ namespace MQTTnet.Packets.Properties
     public class SubscriptionIdentifierProperty : VariableByteIntegerProperty
     {
         public SubscriptionIdentifierProperty(uint value) 
-            : base((byte)PropertyID.SubscriptionIdentifier, value)
+            : base((byte)MqttMessagePropertyID.SubscriptionIdentifier, value)
         {
         }
     }

Source/MQTTnet/Packets/Properties/TopicAliasMaximumProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class TopicAliasMaximumProperty : TwoByteIntegerProperty
+    {
+        public TopicAliasMaximumProperty(ushort value)
+            : base((byte)MqttMessagePropertyID.TopicAliasMaximum, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/TopicAliasProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class TopicAliasProperty : TwoByteIntegerProperty
+    {
+        public TopicAliasProperty(ushort value) 
+            : base((byte)MqttMessagePropertyID.TopicAlias, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/UserPropertyProperty.cs

@@ -0,0 +1,29 @@
+using System;
+using MQTTnet.Formatter;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class UserPropertyProperty : IProperty
+    {
+        public UserPropertyProperty(string name, string value)
+        {
+            Name = name ?? throw new ArgumentNullException(nameof(name));
+            Value = value ?? throw new ArgumentNullException(nameof(value));
+        }
+
+        public byte Id { get; } = (byte)MqttMessagePropertyID.UserProperty;
+
+        public string Name { get; }
+
+        public string Value { get; }
+
+        public void WriteTo(MqttPacketWriter writer)
+        {
+            if (writer == null) throw new ArgumentNullException(nameof(writer));
+            
+            writer.Write(Id);
+            writer.WriteWithLengthPrefix(Name);
+            writer.WriteWithLengthPrefix(Value);
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/WildcardSubscriptionAvailableProperty.cs

@@ -0,0 +1,12 @@
+using MQTTnet.Packets.Properties.BaseTypes;
+
+namespace MQTTnet.Packets.Properties
+{
+    public class WildcardSubscriptionAvailableProperty : ByteProperty
+    {
+        public WildcardSubscriptionAvailableProperty(byte value)
+            : base((byte)MqttMessagePropertyID.WildcardSubscriptionAvailable, value)
+        {
+        }
+    }
+}

Source/MQTTnet/Packets/Properties/WillDelayIntervalProperty.cs

@@ -5,7 +5,7 @@ namespace MQTTnet.Packets.Properties
     public class WillDelayIntervalProperty : FourByteIntegerValue
     {
         public WillDelayIntervalProperty(uint value) 
-            : base((byte)PropertyID.WillDelayInterval, value)
+            : base((byte)MqttMessagePropertyID.WillDelayInterval, value)
         {
         }
     }

Source/MQTTnet/Protocol/MqttAuthenticateReasonCode.cs

@@ -0,0 +1,9 @@
+namespace MQTTnet.Protocol
+{
+    public enum MqttAuthenticateReasonCode
+    {
+        Success = 0,
+        ContinueAuthentication = 24,
+        ReAuthenticate = 25
+    }
+}

Source/MQTTnet/Serializer/IMqttPacketSerializer.cs

@@ -1,15 +0,0 @@
-using System;
-using MQTTnet.Adapter;
-using MQTTnet.Packets;
-
-namespace MQTTnet.Serializer
-{
-    public interface IMqttPacketSerializer
-    {
-        ArraySegment<byte> Serialize(MqttBasePacket mqttPacket);
-
-        MqttBasePacket Deserialize(ReceivedMqttPacket receivedMqttPacket);
-
-        void FreeBuffer();
-    }
-}

Source/MQTTnet/Serializer/MqttV500PacketSerializer.cs

@@ -1,96 +0,0 @@
-using System;
-using MQTTnet.Adapter;
-using MQTTnet.Exceptions;
-using MQTTnet.Packets;
-using MQTTnet.Protocol;
-
-namespace MQTTnet.Serializer
-{
-    public class MqttV500PacketSerializer : MqttV311PacketSerializer
-    {
-        //public ArraySegment<byte> Serialize(MqttBasePacket mqttPacket)
-        //{
-        //    throw new NotImplementedException();
-        //}
-
-        //public MqttBasePacket Deserialize(ReceivedMqttPacket receivedMqttPacket)
-        //{
-        //    throw new NotImplementedException();
-        //}
-
-        protected override byte SerializeConnectPacket(MqttConnectPacket packet, MqttPacketWriter packetWriter)
-        {
-            ValidateConnectPacket(packet);
-
-            packetWriter.WriteWithLengthPrefix("MQTT");
-            packetWriter.Write(5); // [3.1.2.2 Protocol Version]
-
-            byte connectFlags = 0x0;
-            if (packet.CleanSession)
-            {
-                connectFlags |= 0x2;
-            }
-
-            if (packet.WillMessage != null)
-            {
-                connectFlags |= 0x4;
-                connectFlags |= (byte)((byte)packet.WillMessage.QualityOfServiceLevel << 3);
-
-                if (packet.WillMessage.Retain)
-                {
-                    connectFlags |= 0x20;
-                }
-            }
-
-            if (packet.Password != null && packet.Username == null)
-            {
-                throw new MqttProtocolViolationException("If the User Name Flag is set to 0, the Password Flag MUST be set to 0 [MQTT-3.1.2-22].");
-            }
-
-            if (packet.Password != null)
-            {
-                connectFlags |= 0x40;
-            }
-
-            if (packet.Username != null)
-            {
-                connectFlags |= 0x80;
-            }
-
-            packetWriter.Write(connectFlags);
-            packetWriter.Write(packet.KeepAlivePeriod);
-            packetWriter.WriteWithLengthPrefix(packet.ClientId);
-
-            if (packet.WillMessage != null)
-            {
-                packetWriter.WriteWithLengthPrefix(packet.WillMessage.Topic);
-                packetWriter.WriteWithLengthPrefix(packet.WillMessage.Payload);
-            }
-
-            if (packet.Username != null)
-            {
-                packetWriter.WriteWithLengthPrefix(packet.Username);
-            }
-
-            if (packet.Password != null)
-            {
-                packetWriter.WriteWithLengthPrefix(packet.Password);
-            }
-
-            if (packet.Properties != null)
-            {
-                var propertyWriter = new MqttPacketWriter();
-                foreach (var property in packet.Properties)
-                {
-                    propertyWriter.Write(property.Id);
-                    property.WriteTo(propertyWriter);
-                }
-
-                packetWriter.WriteVariableLengthInteger((uint)propertyWriter.Length);
-                packetWriter.Write(propertyWriter);
-            }
-
-            return MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Connect);
-        }
-    }
-}

Source/MQTTnet/Server/IMqttClientSessionStatus.cs

@@ -1,6 +1,6 @@
 using System;
 using System.Threading.Tasks;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Server
 {

Source/MQTTnet/Server/MqttClientSessionStatus.cs

@@ -1,6 +1,6 @@
 using System;
 using System.Threading.Tasks;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Server
 {

Tests/MQTTnet.AspNetCore.Tests/MqttConnectionContextTest.cs

@@ -3,11 +3,11 @@ using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.AspNetCore.Tests.Mockups;
 using MQTTnet.Exceptions;
 using MQTTnet.Packets;
-using MQTTnet.Serializer;
 using System;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.AspNetCore.Tests
 {

Tests/MQTTnet.AspNetCore.Tests/ReaderExtensionsTest.cs

@@ -2,8 +2,8 @@
 using System.Buffers;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.AspNetCore;
+using MQTTnet.Formatter.V311;
 using MQTTnet.Packets;
-using MQTTnet.Serializer;
 
 namespace MQTTnet.AspNetCore.Tests
 {
@@ -13,9 +13,9 @@ namespace MQTTnet.AspNetCore.Tests
         [TestMethod]
         public void TestTryDeserialize()
         {
-            var serializer = new MqttV311PacketSerializer();
+            var serializer = new MqttV311PacketFormatter();
 
-            var buffer = serializer.Serialize(new MqttPublishPacket() {Topic = "a", Payload = new byte[5]});
+            var buffer = serializer.Encode(new MqttPublishPacket() {Topic = "a", Payload = new byte[5]});
 
             var sequence = new ReadOnlySequence<byte>(buffer.Array, buffer.Offset, buffer.Count);
 

Tests/MQTTnet.Benchmarks/ChannelAdapterBenchmark.cs

@@ -3,10 +3,10 @@ using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
 using MQTTnet.Internal;
 using MQTTnet.Packets;
-using MQTTnet.Serializer;
 using System;
 using System.IO;
 using System.Threading;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Benchmarks
 {
@@ -28,7 +28,7 @@ namespace MQTTnet.Benchmarks
             _packet = message.ToPublishPacket();
             var serializer = new MqttPacketSerializerAdapter(MqttProtocolVersion.V311);
             
-            var serializedPacket = Join(serializer.Serialize(_packet));
+            var serializedPacket = Join(serializer.Encode(_packet));
 
             _iterations = 10000;
 

Tests/MQTTnet.Benchmarks/SerializerBenchmark.cs

@@ -1,12 +1,13 @@
 using BenchmarkDotNet.Attributes;
 using MQTTnet.Packets;
-using MQTTnet.Serializer;
 using MQTTnet.Internal;
 using System;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Adapter;
 using MQTTnet.Channel;
+using MQTTnet.Formatter;
+using MQTTnet.Formatter.V311;
 
 namespace MQTTnet.Benchmarks
 {
@@ -17,7 +18,7 @@ namespace MQTTnet.Benchmarks
     {
         private MqttBasePacket _packet;
         private ArraySegment<byte> _serializedPacket;
-        private IMqttPacketSerializer _serializer;
+        private IMqttPacketFormatter _serializer;
 
         [GlobalSetup]
         public void Setup()
@@ -27,8 +28,8 @@ namespace MQTTnet.Benchmarks
                 .Build();
 
             _packet = message.ToPublishPacket();
-            _serializer = new MqttV311PacketSerializer();
-            _serializedPacket = _serializer.Serialize(_packet);
+            _serializer = new MqttV311PacketFormatter();
+            _serializedPacket = _serializer.Encode(_packet);
         }
 
         [Benchmark]
@@ -36,7 +37,7 @@ namespace MQTTnet.Benchmarks
         {
             for (var i = 0; i < 10000; i++)
             {
-                _serializer.Serialize(_packet);
+                _serializer.Encode(_packet);
                 _serializer.FreeBuffer();
             }
         }
@@ -58,7 +59,7 @@ namespace MQTTnet.Benchmarks
                     header.Flags,
                     new MqttPacketBodyReader(_serializedPacket.Array, _serializedPacket.Count - header.RemainingLength, _serializedPacket.Array.Length));
 
-                _serializer.Deserialize(receivedPacket);
+                _serializer.Decode(receivedPacket);
             }
         }
 

Tests/MQTTnet.Core.Tests/MqttPacketReaderTests.cs

@@ -2,8 +2,8 @@
 using System.Threading;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Exceptions;
+using MQTTnet.Formatter;
 using MQTTnet.Internal;
-using MQTTnet.Serializer;
 
 namespace MQTTnet.Core.Tests
 {

Tests/MQTTnet.Core.Tests/MqttPacketSerializerTests.cs

@@ -5,10 +5,12 @@ using System.Text;
 using System.Threading;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Adapter;
+using MQTTnet.Formatter;
+using MQTTnet.Formatter.V310;
+using MQTTnet.Formatter.V311;
 using MQTTnet.Internal;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
-using MQTTnet.Serializer;
 
 namespace MQTTnet.Core.Tests
 {
@@ -153,7 +155,7 @@ namespace MQTTnet.Core.Tests
         [TestMethod]
         public void Serialize_LargePacket()
         {
-            var serializer = new MqttV311PacketSerializer();
+            var serializer = new MqttV311PacketFormatter();
 
             const int payloadLength = 80000;
 
@@ -176,7 +178,7 @@ namespace MQTTnet.Core.Tests
                 Payload = payload
             };
 
-            var buffer = serializer.Serialize(publishPacket);
+            var buffer = serializer.Encode(publishPacket);
             var testChannel = new TestMqttChannel(new MemoryStream(buffer.Array, buffer.Offset, buffer.Count));
 
             var header = MqttPacketReader.ReadFixedHeaderAsync(
@@ -191,7 +193,7 @@ namespace MQTTnet.Core.Tests
                 header.Flags,
                 new MqttPacketBodyReader(buffer.Array, eof - header.RemainingLength, buffer.Count + buffer.Offset));
 
-            var packet = (MqttPublishPacket)serializer.Deserialize(receivedPacket);
+            var packet = (MqttPublishPacket)serializer.Decode(receivedPacket);
 
             Assert.AreEqual(publishPacket.Topic, packet.Topic);
             Assert.IsTrue(publishPacket.Payload.SequenceEqual(packet.Payload));
@@ -509,42 +511,42 @@ namespace MQTTnet.Core.Tests
 
         private static void SerializeAndCompare(MqttBasePacket packet, string expectedBase64Value, MqttProtocolVersion protocolVersion = MqttProtocolVersion.V311)
         {
-            IMqttPacketSerializer serializer;
+            IMqttPacketFormatter serializer;
             if (protocolVersion == MqttProtocolVersion.V311)
             {
-                serializer = new MqttV311PacketSerializer();
+                serializer = new MqttV311PacketFormatter();
             }
             else if (protocolVersion == MqttProtocolVersion.V310)
             {
-                serializer = new MqttV310PacketSerializer();
+                serializer = new MqttV310PacketFormatter();
             }
             else
             {
                 throw new NotSupportedException();
             }
 
-            var data = serializer.Serialize(packet);
+            var data = serializer.Encode(packet);
 
             Assert.AreEqual(expectedBase64Value, Convert.ToBase64String(Join(data)));
         }
 
         private static void DeserializeAndCompare(MqttBasePacket packet, string expectedBase64Value, MqttProtocolVersion protocolVersion = MqttProtocolVersion.V311)
         {
-            IMqttPacketSerializer serializer;
+            IMqttPacketFormatter serializer;
             if (protocolVersion == MqttProtocolVersion.V311)
             {
-                serializer = new MqttV311PacketSerializer();
+                serializer = new MqttV311PacketFormatter();
             }
             else if (protocolVersion == MqttProtocolVersion.V310)
             {
-                serializer = new MqttV310PacketSerializer();
+                serializer = new MqttV310PacketFormatter();
             }
             else
             {
                 throw new NotSupportedException();
             }
 
-            var buffer1 = serializer.Serialize(packet);
+            var buffer1 = serializer.Encode(packet);
 
             using (var headerStream = new MemoryStream(Join(buffer1)))
             {
@@ -555,8 +557,8 @@ namespace MQTTnet.Core.Tests
 
                 using (var bodyStream = new MemoryStream(Join(buffer1), (int)headerStream.Position, header.RemainingLength))
                 {
-                    var deserializedPacket = serializer.Deserialize(new ReceivedMqttPacket(header.Flags, new MqttPacketBodyReader(bodyStream.ToArray(), 0, (int)bodyStream.Length)));
-                    var buffer2 = serializer.Serialize(deserializedPacket);
+                    var deserializedPacket = serializer.Decode(new ReceivedMqttPacket(header.Flags, new MqttPacketBodyReader(bodyStream.ToArray(), 0, (int)bodyStream.Length)));
+                    var buffer2 = serializer.Encode(deserializedPacket);
 
                     Assert.AreEqual(expectedBase64Value, Convert.ToBase64String(Join(buffer2)));
                 }
@@ -566,21 +568,21 @@ namespace MQTTnet.Core.Tests
         private static T Roundtrip<T>(T packet, MqttProtocolVersion protocolVersion = MqttProtocolVersion.V311)
             where T : MqttBasePacket
         {
-            IMqttPacketSerializer serializer;
+            IMqttPacketFormatter serializer;
             if (protocolVersion == MqttProtocolVersion.V311)
             {
-                serializer = new MqttV311PacketSerializer();
+                serializer = new MqttV311PacketFormatter();
             }
             else if (protocolVersion == MqttProtocolVersion.V310)
             {
-                serializer = new MqttV310PacketSerializer();
+                serializer = new MqttV310PacketFormatter();
             }
             else
             {
                 throw new NotSupportedException();
             }
 
-            var buffer1 = serializer.Serialize(packet);
+            var buffer1 = serializer.Encode(packet);
 
             using (var headerStream = new MemoryStream(Join(buffer1)))
             {
@@ -592,7 +594,7 @@ namespace MQTTnet.Core.Tests
 
                 using (var bodyStream = new MemoryStream(Join(buffer1), (int)headerStream.Position, header.RemainingLength))
                 {
-                    return (T)serializer.Deserialize(new ReceivedMqttPacket(header.Flags, new MqttPacketBodyReader(bodyStream.ToArray(), 0, (int)bodyStream.Length)));
+                    return (T)serializer.Decode(new ReceivedMqttPacket(header.Flags, new MqttPacketBodyReader(bodyStream.ToArray(), 0, (int)bodyStream.Length)));
                 }
             }
         }

Tests/MQTTnet.Core.Tests/MqttPacketWriterTests.cs

@@ -1,5 +1,5 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Serializer;
+using MQTTnet.Formatter;
 
 namespace MQTTnet.Core.Tests
 {

Tests/MQTTnet.Core.Tests/TestMqttCommunicationAdapter.cs

@@ -3,8 +3,8 @@ using System.Collections.Concurrent;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Adapter;
+using MQTTnet.Formatter;
 using MQTTnet.Packets;
-using MQTTnet.Serializer;
 
 namespace MQTTnet.Core.Tests
 {

Tests/MQTTnet.TestApp.UniversalWindows/MainPage.xaml

@@ -37,6 +37,7 @@
                             <RowDefinition></RowDefinition>
                             <RowDefinition></RowDefinition>
                             <RowDefinition></RowDefinition>
+                            <RowDefinition></RowDefinition>
                         </Grid.RowDefinitions>
 
                         <TextBlock Grid.Column="0" Grid.Row="0">Server:</TextBlock>
@@ -57,12 +58,19 @@
                         <TextBlock Grid.Column="0" Grid.Row="5">Keep Alive interval:</TextBlock>
                         <TextBox Grid.Column="1" Grid.Row="5" x:Name="KeepAliveInterval" Text="5"></TextBox>
 
-                        <TextBlock Grid.Column="0" Grid.Row="6">Protocol:</TextBlock>
+                        <TextBlock Grid.Column="0" Grid.Row="6">Transport:</TextBlock>
                         <StackPanel Grid.Column="1" Grid.Row="6" Orientation="Horizontal">
-                            <RadioButton x:Name="UseTcp" IsChecked="True" GroupName="connection">TCP</RadioButton>
-                            <RadioButton x:Name="UseWs" GroupName="connection">WS</RadioButton>
+                            <RadioButton x:Name="UseTcp" IsChecked="True" GroupName="transport">TCP</RadioButton>
+                            <RadioButton x:Name="UseWs" GroupName="transport">WS</RadioButton>
                             <CheckBox x:Name="UseTls">Use TLS</CheckBox>
                         </StackPanel>
+
+                        <TextBlock Grid.Column="0" Grid.Row="7">Protocol:</TextBlock>
+                        <StackPanel Grid.Column="1" Grid.Row="7" Orientation="Horizontal">
+                            <RadioButton x:Name="UseMqtt500" GroupName="protocol">5.0.0</RadioButton>
+                            <RadioButton x:Name="UseMqtt311" GroupName="protocol" IsChecked="True">3.1.1</RadioButton>
+                            <RadioButton x:Name="UseMqtt310" GroupName="protocol">3.1.0</RadioButton>
+                        </StackPanel>
                     </Grid>
                    
                     <CheckBox x:Name="CleanSession" IsChecked="True">Clean session</CheckBox>

Tests/MQTTnet.TestApp.UniversalWindows/MainPage.xaml.cs

@@ -12,9 +12,9 @@ using MQTTnet.Diagnostics;
 using MQTTnet.Exceptions;
 using MQTTnet.Extensions.ManagedClient;
 using MQTTnet.Extensions.Rpc;
+using MQTTnet.Formatter;
 using MQTTnet.Implementations;
 using MQTTnet.Protocol;
-using MQTTnet.Serializer;
 using MQTTnet.Server;
 using MqttClientConnectedEventArgs = MQTTnet.Client.MqttClientConnectedEventArgs;
 using MqttClientDisconnectedEventArgs = MQTTnet.Client.MqttClientDisconnectedEventArgs;
@@ -124,7 +124,20 @@ namespace MQTTnet.TestApp.UniversalWindows
 
             options.CleanSession = CleanSession.IsChecked == true;
             options.KeepAlivePeriod = TimeSpan.FromSeconds(double.Parse(KeepAliveInterval.Text));
-            
+
+            if (UseMqtt310.IsChecked == true)
+            {
+                options.ProtocolVersion = MqttProtocolVersion.V310;
+            }
+            else if (UseMqtt311.IsChecked == true)
+            {
+                options.ProtocolVersion = MqttProtocolVersion.V311;
+            }
+            else if (UseMqtt500.IsChecked == true)
+            {
+                options.ProtocolVersion = MqttProtocolVersion.V500;
+            }
+
             try
             {
                 if (_mqttClient != null)
@@ -426,14 +439,14 @@ namespace MQTTnet.TestApp.UniversalWindows
             _sessions.Clear();
         }
 
-        private async void RefreshSessions(object sender, RoutedEventArgs e)
+        private void RefreshSessions(object sender, RoutedEventArgs e)
         {
             if (_mqttServer == null)
             {
                 return;
             }
 
-            var sessions = await _mqttServer.GetClientSessionsStatusAsync();
+            var sessions = _mqttServer.GetClientSessionsStatus();
             _sessions.Clear();
 
             foreach (var session in sessions)