Refactor tracing

Build/MQTTnet.nuspec

@@ -11,6 +11,9 @@
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>MQTTnet is a .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker).</description>
     <releaseNotes>* [Core] Merged the .NET Framwork and netstandard projects (Thanks to @JanEggers)
+* [Core] Migrated the trace to a non-static approach (Breaking Change!)
+* [Core] Added a builder for application messages using a fluent API
+* [Client] Added a first version of a managed client which will manage the connection, subscription etc. automatically (Thanks to @JTrotta)
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2017</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M</tags> 

Frameworks/MQTTnet.NetStandard/Implementations/MqttCommunicationAdapterFactory.cs

@@ -1,6 +1,7 @@
 using System;
 using MQTTnet.Core.Adapter;
 using MQTTnet.Core.Client;
+using MQTTnet.Core.Diagnostics;
 using MQTTnet.Core.Serializer;
 
 namespace MQTTnet.Implementations
@@ -13,12 +14,14 @@ namespace MQTTnet.Implementations
 
             if (options is MqttClientTcpOptions tcpOptions)
             {
-                return new MqttChannelCommunicationAdapter(new MqttTcpChannel(tcpOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion });
+                var trace = new MqttNetTrace();
+                return new MqttChannelCommunicationAdapter(new MqttTcpChannel(tcpOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion }, trace);
             }
 
             if (options is MqttClientWebSocketOptions webSocketOptions)
             {
-                return new MqttChannelCommunicationAdapter(new MqttWebSocketChannel(webSocketOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion });
+                var trace = new MqttNetTrace();
+                return new MqttChannelCommunicationAdapter(new MqttWebSocketChannel(webSocketOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion }, trace);
             }
 
             throw new NotSupportedException();

Frameworks/MQTTnet.NetStandard/Implementations/MqttServerAdapter.cs

@@ -15,11 +15,17 @@ namespace MQTTnet.Implementations
 {
     public class MqttServerAdapter : IMqttServerAdapter, IDisposable
     {
+        private readonly MqttNetTrace _trace;
         private CancellationTokenSource _cancellationTokenSource;
         private Socket _defaultEndpointSocket;
         private Socket _tlsEndpointSocket;
         private X509Certificate2 _tlsCertificate;
 
+        public MqttServerAdapter(MqttNetTrace trace)
+        {
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
+        }
+
         public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
 
         public Task StartAsync(MqttServerOptions options)
@@ -94,12 +100,12 @@ namespace MQTTnet.Implementations
 #else
                     var clientSocket = await _defaultEndpointSocket.AcceptAsync().ConfigureAwait(false);
 #endif
-                    var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(clientSocket, null), new MqttPacketSerializer());
+                    var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(clientSocket, null), new MqttPacketSerializer(), _trace);
                     ClientAccepted?.Invoke(this, new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
                 }
                 catch (Exception exception)
                 {
-                    MqttNetTrace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at default endpoint.");
+                    _trace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at default endpoint.");
 
                     //excessive CPU consumed if in endless loop of socket errors
                     await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);
@@ -122,12 +128,12 @@ namespace MQTTnet.Implementations
                     var sslStream = new SslStream(new NetworkStream(clientSocket));
                     await sslStream.AuthenticateAsServerAsync(_tlsCertificate, false, SslProtocols.Tls12, false).ConfigureAwait(false);
 
-                    var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(clientSocket, sslStream), new MqttPacketSerializer());
+                    var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(clientSocket, sslStream), new MqttPacketSerializer(), _trace);
                     ClientAccepted?.Invoke(this, new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
                 }
                 catch (Exception exception)
                 {
-                    MqttNetTrace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at TLS endpoint.");
+                    _trace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at TLS endpoint.");
 
                     //excessive CPU consumed if in endless loop of socket errors
                     await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken).ConfigureAwait(false);

Frameworks/MQTTnet.NetStandard/MqttClientFactory.cs

@@ -1,4 +1,5 @@
 using MQTTnet.Core.Client;
+using MQTTnet.Core.Diagnostics;
 using MQTTnet.Core.ManagedClient;
 using MQTTnet.Implementations;
 
@@ -6,14 +7,14 @@ namespace MQTTnet
 {
     public class MqttClientFactory : IMqttClientFactory
     {
-        public IMqttClient CreateMqttClient()
+        public IMqttClient CreateMqttClient(IMqttNetTraceHandler traceHandler = null)
         {
-            return new MqttClient(new MqttCommunicationAdapterFactory());
+            return new MqttClient(new MqttCommunicationAdapterFactory(), new MqttNetTrace(traceHandler));
         }
 
-        public ManagedMqttClient CreateManagedMqttClient()
+        public ManagedMqttClient CreateManagedMqttClient(IMqttNetTraceHandler traceHandler = null)
         {
-            return new ManagedMqttClient(new MqttCommunicationAdapterFactory());
+            return new ManagedMqttClient(new MqttCommunicationAdapterFactory(), new MqttNetTrace());
         }
     }
 }

Frameworks/MQTTnet.NetStandard/MqttServerFactory.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using MQTTnet.Core.Adapter;
+using MQTTnet.Core.Diagnostics;
 using MQTTnet.Core.Server;
 using MQTTnet.Implementations;
 
@@ -8,11 +9,12 @@ namespace MQTTnet
 {
     public class MqttServerFactory : IMqttServerFactory
     {
-        public IMqttServer CreateMqttServer(MqttServerOptions options)
+        public IMqttServer CreateMqttServer(MqttServerOptions options, IMqttNetTraceHandler traceHandler = null)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 
-            return new MqttServer(options, new List<IMqttServerAdapter> { new MqttServerAdapter() });
+            var trace = new MqttNetTrace(traceHandler);
+            return new MqttServer(options, new List<IMqttServerAdapter> { new MqttServerAdapter(trace) }, trace);
         }
     }
 }

Frameworks/MQTTnet.UniversalWindows/Implementations/MqttCommunicationAdapterFactory.cs

@@ -1,6 +1,7 @@
 using System;
 using MQTTnet.Core.Adapter;
 using MQTTnet.Core.Client;
+using MQTTnet.Core.Diagnostics;
 using MQTTnet.Core.Serializer;
 
 namespace MQTTnet.Implementations
@@ -13,12 +14,14 @@ namespace MQTTnet.Implementations
 
             if (options is MqttClientTcpOptions tcpOptions)
             {
-                return new MqttChannelCommunicationAdapter(new MqttTcpChannel(tcpOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion });
+                var trace = new MqttNetTrace();
+                return new MqttChannelCommunicationAdapter(new MqttTcpChannel(tcpOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion }, trace);
             }
 
             if (options is MqttClientWebSocketOptions webSocketOptions)
             {
-                return new MqttChannelCommunicationAdapter(new MqttWebSocketChannel(webSocketOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion });
+                var trace = new MqttNetTrace();
+                return new MqttChannelCommunicationAdapter(new MqttWebSocketChannel(webSocketOptions), new MqttPacketSerializer { ProtocolVersion = options.ProtocolVersion }, trace);
             }
 
             throw new NotSupportedException();

Frameworks/MQTTnet.UniversalWindows/Implementations/MqttServerAdapter.cs

@@ -10,8 +10,14 @@ namespace MQTTnet.Implementations
 {
     public class MqttServerAdapter : IMqttServerAdapter, IDisposable
     {
+        private readonly MqttNetTrace _trace;
         private StreamSocketListener _defaultEndpointSocket;
 
+        public MqttServerAdapter(MqttNetTrace trace)
+        {
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
+        }
+
         public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
 
         public async Task StartAsync(MqttServerOptions options)
@@ -50,12 +56,12 @@ namespace MQTTnet.Implementations
         {
             try
             {
-                var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(args.Socket), new MqttPacketSerializer());
+                var clientAdapter = new MqttChannelCommunicationAdapter(new MqttTcpChannel(args.Socket), new MqttPacketSerializer(), _trace);
                 ClientAccepted?.Invoke(this, new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at default endpoint.");
+                _trace.Error(nameof(MqttServerAdapter), exception, "Error while accepting connection at default endpoint.");
             }
         }
     }

Frameworks/MQTTnet.UniversalWindows/MqttClientFactory.cs

@@ -1,4 +1,5 @@
 using MQTTnet.Core.Client;
+using MQTTnet.Core.Diagnostics;
 using MQTTnet.Core.ManagedClient;
 using MQTTnet.Implementations;
 
@@ -6,14 +7,14 @@ namespace MQTTnet
 {
     public class MqttClientFactory : IMqttClientFactory
     {
-        public IMqttClient CreateMqttClient()
+        public IMqttClient CreateMqttClient(IMqttNetTraceHandler traceHandler = null)
         {
-            return new MqttClient(new MqttCommunicationAdapterFactory());
+            return new MqttClient(new MqttCommunicationAdapterFactory(), new MqttNetTrace(traceHandler));
         }
 
-        public ManagedMqttClient CreateManagedMqttClient()
+        public ManagedMqttClient CreateManagedMqttClient(IMqttNetTraceHandler traceHandler = null)
         {
-            return new ManagedMqttClient(new MqttCommunicationAdapterFactory());
+            return new ManagedMqttClient(new MqttCommunicationAdapterFactory(), new MqttNetTrace(traceHandler));
         }
     }
 }

Frameworks/MQTTnet.UniversalWindows/MqttServerFactory.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using MQTTnet.Core.Adapter;
+using MQTTnet.Core.Diagnostics;
 using MQTTnet.Core.Server;
 using MQTTnet.Implementations;
 
@@ -8,11 +9,12 @@ namespace MQTTnet
 {
     public class MqttServerFactory : IMqttServerFactory
     {
-        public IMqttServer CreateMqttServer(MqttServerOptions options)
+        public IMqttServer CreateMqttServer(MqttServerOptions options, IMqttNetTraceHandler traceHandler = null)
         {
             if (options == null) throw new ArgumentNullException(nameof(options));
 
-            return new MqttServer(options, new List<IMqttServerAdapter> { new MqttServerAdapter() });
+            var trace = new MqttNetTrace(traceHandler);
+            return new MqttServer(options, new List<IMqttServerAdapter> { new MqttServerAdapter(trace) }, trace);
         }
     }
 }

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2017 Christian
+Copyright (c) 2017 Christian Kratky
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

MQTTnet.Core/Adapter/MqttChannelCommunicationAdapter.cs

@@ -14,11 +14,13 @@ namespace MQTTnet.Core.Adapter
 {
     public class MqttChannelCommunicationAdapter : IMqttCommunicationAdapter
     {
+        private readonly MqttNetTrace _trace;
         private readonly IMqttCommunicationChannel _channel;
         private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1, 1);
 
-        public MqttChannelCommunicationAdapter(IMqttCommunicationChannel channel, IMqttPacketSerializer serializer)
+        public MqttChannelCommunicationAdapter(IMqttCommunicationChannel channel, IMqttPacketSerializer serializer, MqttNetTrace trace)
         {
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
             _channel = channel ?? throw new ArgumentNullException(nameof(channel));
             PacketSerializer = serializer ?? throw new ArgumentNullException(nameof(serializer));
         }
@@ -94,7 +96,7 @@ namespace MQTTnet.Core.Adapter
                         continue;
                     }
 
-                    MqttNetTrace.Information(nameof(MqttChannelCommunicationAdapter), "TX >>> {0} [Timeout={1}]", packet, timeout);
+                    _trace.Information(nameof(MqttChannelCommunicationAdapter), "TX >>> {0} [Timeout={1}]", packet, timeout);
 
                     var writeBuffer = PacketSerializer.Serialize(packet);
                     await _channel.SendStream.WriteAsync(writeBuffer, 0, writeBuffer.Length, cancellationToken).ConfigureAwait(false);
@@ -160,7 +162,7 @@ namespace MQTTnet.Core.Adapter
                     throw new MqttProtocolViolationException("Received malformed packet.");
                 }
 
-                MqttNetTrace.Information(nameof(MqttChannelCommunicationAdapter), "RX <<< {0}", packet);
+                _trace.Information(nameof(MqttChannelCommunicationAdapter), "RX <<< {0}", packet);
                 return packet;
             }
             catch (TaskCanceledException)

MQTTnet.Core/Client/IMqttClientFactory.cs

@@ -1,11 +1,12 @@
-using MQTTnet.Core.ManagedClient;
+using MQTTnet.Core.Diagnostics;
+using MQTTnet.Core.ManagedClient;
 
 namespace MQTTnet.Core.Client
 {
     public interface IMqttClientFactory
     {
-        IMqttClient CreateMqttClient();
+        IMqttClient CreateMqttClient(IMqttNetTraceHandler traceHandler = null);
 
-        ManagedMqttClient CreateManagedMqttClient();
+        ManagedMqttClient CreateManagedMqttClient(IMqttNetTraceHandler traceHandler = null);
     }
 }

MQTTnet.Core/Client/MqttClient.cs

@@ -15,8 +15,9 @@ namespace MQTTnet.Core.Client
     public class MqttClient : IMqttClient
     {
         private readonly HashSet<ushort> _unacknowledgedPublishPackets = new HashSet<ushort>();
-        private readonly MqttPacketDispatcher _packetDispatcher = new MqttPacketDispatcher();
+        private readonly MqttPacketDispatcher _packetDispatcher;
         private readonly IMqttCommunicationAdapterFactory _communicationChannelFactory;
+        private readonly MqttNetTrace _trace;
 
         private IMqttClientOptions _options;
         private bool _isReceivingPackets;
@@ -24,9 +25,12 @@ namespace MQTTnet.Core.Client
         private CancellationTokenSource _cancellationTokenSource;
         private IMqttCommunicationAdapter _adapter;
 
-        public MqttClient(IMqttCommunicationAdapterFactory communicationChannelFactory)
+        public MqttClient(IMqttCommunicationAdapterFactory communicationChannelFactory, MqttNetTrace trace)
         {
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
             _communicationChannelFactory = communicationChannelFactory ?? throw new ArgumentNullException(nameof(communicationChannelFactory));
+
+            _packetDispatcher = new MqttPacketDispatcher(trace);
         }
 
         public event EventHandler Connected;
@@ -50,14 +54,14 @@ namespace MQTTnet.Core.Client
 
                 _adapter = _communicationChannelFactory.CreateMqttCommunicationAdapter(options);
 
-                MqttNetTrace.Verbose(nameof(MqttClient), "Trying to connect with server.");
+                _trace.Verbose(nameof(MqttClient), "Trying to connect with server.");
                 await _adapter.ConnectAsync(_options.DefaultCommunicationTimeout).ConfigureAwait(false);
-                MqttNetTrace.Verbose(nameof(MqttClient), "Connection with server established.");
+                _trace.Verbose(nameof(MqttClient), "Connection with server established.");
 
                 await SetupIncomingPacketProcessingAsync();
                 await AuthenticateAsync(options.WillMessage);
 
-                MqttNetTrace.Verbose(nameof(MqttClient), "MQTT connection with server established.");
+                _trace.Verbose(nameof(MqttClient), "MQTT connection with server established.");
 
                 if (_options.KeepAlivePeriod != TimeSpan.Zero)
                 {
@@ -239,11 +243,11 @@ namespace MQTTnet.Core.Client
             try
             {
                 await _adapter.DisconnectAsync(_options.DefaultCommunicationTimeout).ConfigureAwait(false);
-                MqttNetTrace.Information(nameof(MqttClient), "Disconnected from adapter.");
+                _trace.Information(nameof(MqttClient), "Disconnected from adapter.");
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Warning(nameof(MqttClient), exception, "Error while disconnecting from adapter.");
+                _trace.Warning(nameof(MqttClient), exception, "Error while disconnecting from adapter.");
             }
             finally
             {
@@ -255,7 +259,7 @@ namespace MQTTnet.Core.Client
         {
             try
             {
-                MqttNetTrace.Information(nameof(MqttClient), "Received <<< {0}", packet);
+                _trace.Information(nameof(MqttClient), "Received <<< {0}", packet);
 
                 if (packet is MqttPingReqPacket)
                 {
@@ -285,7 +289,7 @@ namespace MQTTnet.Core.Client
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttClient), exception, "Unhandled exception while processing received packet.");
+                _trace.Error(nameof(MqttClient), exception, "Unhandled exception while processing received packet.");
             }
         }
 
@@ -298,7 +302,7 @@ namespace MQTTnet.Core.Client
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttClient), exception, "Unhandled exception while handling application message.");
+                _trace.Error(nameof(MqttClient), exception, "Unhandled exception while handling application message.");
             }
         }
 
@@ -362,7 +366,7 @@ namespace MQTTnet.Core.Client
 
         private async Task SendKeepAliveMessagesAsync(CancellationToken cancellationToken)
         {
-            MqttNetTrace.Information(nameof(MqttClient), "Start sending keep alive packets.");
+            _trace.Information(nameof(MqttClient), "Start sending keep alive packets.");
 
             try
             {
@@ -387,23 +391,23 @@ namespace MQTTnet.Core.Client
                     return;
                 }
 
-                MqttNetTrace.Warning(nameof(MqttClient), exception, "MQTT communication exception while sending/receiving keep alive packets.");
+                _trace.Warning(nameof(MqttClient), exception, "MQTT communication exception while sending/receiving keep alive packets.");
                 await DisconnectInternalAsync().ConfigureAwait(false);
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Warning(nameof(MqttClient), exception, "Unhandled exception while sending/receiving keep alive packets.");
+                _trace.Warning(nameof(MqttClient), exception, "Unhandled exception while sending/receiving keep alive packets.");
                 await DisconnectInternalAsync().ConfigureAwait(false);
             }
             finally
             {
-                MqttNetTrace.Information(nameof(MqttClient), "Stopped sending keep alive packets.");
+                _trace.Information(nameof(MqttClient), "Stopped sending keep alive packets.");
             }
         }
 
         private async Task ReceivePackets(CancellationToken cancellationToken)
         {
-            MqttNetTrace.Information(nameof(MqttClient), "Start receiving packets.");
+            _trace.Information(nameof(MqttClient), "Start receiving packets.");
 
             try
             {
@@ -430,17 +434,17 @@ namespace MQTTnet.Core.Client
                     return;
                 }
 
-                MqttNetTrace.Warning(nameof(MqttClient), exception, "MQTT communication exception while receiving packets.");
+                _trace.Warning(nameof(MqttClient), exception, "MQTT communication exception while receiving packets.");
                 await DisconnectInternalAsync().ConfigureAwait(false);
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttClient), exception, "Unhandled exception while receiving packets.");
+                _trace.Error(nameof(MqttClient), exception, "Unhandled exception while receiving packets.");
                 await DisconnectInternalAsync().ConfigureAwait(false);
             }
             finally
             {
-                MqttNetTrace.Information(nameof(MqttClient), "Stopped receiving packets.");
+                _trace.Information(nameof(MqttClient), "Stopped receiving packets.");
             }
         }
 

MQTTnet.Core/Client/MqttPacketDispatcher.cs

@@ -12,6 +12,12 @@ namespace MQTTnet.Core.Client
     {
         private readonly ConcurrentDictionary<Type, TaskCompletionSource<MqttBasePacket>> _packetByResponseType = new ConcurrentDictionary<Type, TaskCompletionSource<MqttBasePacket>>();
         private readonly ConcurrentDictionary<Type, ConcurrentDictionary<ushort, TaskCompletionSource<MqttBasePacket>>> _packetByResponseTypeAndIdentifier = new ConcurrentDictionary<Type, ConcurrentDictionary<ushort, TaskCompletionSource<MqttBasePacket>>>();
+        private readonly MqttNetTrace _trace;
+
+        public MqttPacketDispatcher(MqttNetTrace trace)
+        {
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
+        }
 
         public async Task<MqttBasePacket> WaitForPacketAsync(MqttBasePacket request, Type responseType, TimeSpan timeout)
         {
@@ -24,7 +30,7 @@ namespace MQTTnet.Core.Client
             }
             catch (MqttCommunicationTimedOutException)
             {
-                MqttNetTrace.Warning(nameof(MqttPacketDispatcher), "Timeout while waiting for packet of type '{0}'.", responseType.Name);
+                _trace.Warning(nameof(MqttPacketDispatcher), "Timeout while waiting for packet of type '{0}'.", responseType.Name);
                 throw;
             }
             finally

MQTTnet.Core/Diagnostics/IMqttNetTraceHandler.cs

@@ -0,0 +1,9 @@
+namespace MQTTnet.Core.Diagnostics
+{
+    public interface IMqttNetTraceHandler
+    {
+        bool IsEnabled { get; }
+
+        void HandleTraceMessage(MqttNetTraceMessage traceMessage);
+    }
+}

MQTTnet.Core/Diagnostics/MqttNetTrace.cs

@@ -2,48 +2,62 @@
 
 namespace MQTTnet.Core.Diagnostics
 {
-    public static class MqttNetTrace
+    public sealed class MqttNetTrace : IMqttNetTraceHandler
     {
+        private readonly IMqttNetTraceHandler _traceHandler;
+
+        public MqttNetTrace(IMqttNetTraceHandler traceHandler = null)
+        {
+            _traceHandler = traceHandler ?? this;
+        }
+        
         public static event EventHandler<MqttNetTraceMessagePublishedEventArgs> TraceMessagePublished;
 
-        public static void Verbose(string source, string message, params object[] parameters)
+        public bool IsEnabled => TraceMessagePublished != null;
+
+        public void Verbose(string source, string message, params object[] parameters)
         {
             Publish(source, MqttNetTraceLevel.Verbose, null, message, parameters);
         }
 
-        public static void Information(string source, string message, params object[] parameters)
+        public void Information(string source, string message, params object[] parameters)
         {
             Publish(source, MqttNetTraceLevel.Information, null, message, parameters);
         }
 
-        public static void Warning(string source, string message, params object[] parameters)
+        public void Warning(string source, string message, params object[] parameters)
         {
             Publish(source, MqttNetTraceLevel.Warning, null, message, parameters);
         }
 
-        public static void Warning(string source, Exception exception, string message, params object[] parameters)
+        public void Warning(string source, Exception exception, string message, params object[] parameters)
         {
             Publish(source, MqttNetTraceLevel.Warning, exception, message, parameters);
         }
 
-        public static void Error(string source, string message, params object[] parameters)
+        public void Error(string source, string message, params object[] parameters)
         {
             Publish(source, MqttNetTraceLevel.Error, null, message, parameters);
         }
 
-        public static void Error(string source, Exception exception, string message, params object[] parameters)
+        public void Error(string source, Exception exception, string message, params object[] parameters)
         {
             Publish(source, MqttNetTraceLevel.Error, exception, message, parameters);
         }
 
-        private static void Publish(string source, MqttNetTraceLevel traceLevel, Exception exception, string message, params object[] parameters)
+        public void HandleTraceMessage(MqttNetTraceMessage mqttNetTraceMessage)
         {
-            var handler = TraceMessagePublished;
+            TraceMessagePublished?.Invoke(this, new MqttNetTraceMessagePublishedEventArgs(mqttNetTraceMessage));
-            if (handler == null)
+        }
+
+        private void Publish(string source, MqttNetTraceLevel traceLevel, Exception exception, string message, params object[] parameters)
+        {
+            if (!_traceHandler.IsEnabled)
             {
                 return;
             }
 
+            var now = DateTime.Now;
             if (parameters?.Length > 0)
             {
                 try
@@ -57,7 +71,7 @@ namespace MQTTnet.Core.Diagnostics
                 }
             }
 
-            handler.Invoke(null, new MqttNetTraceMessagePublishedEventArgs(Environment.CurrentManagedThreadId, source, traceLevel, message, exception));
+            _traceHandler.HandleTraceMessage(new MqttNetTraceMessage(now, Environment.CurrentManagedThreadId, source, traceLevel, message, exception));
         }
     }
 }

MQTTnet.Core/Diagnostics/MqttNetTraceMessage.cs

@@ -0,0 +1,29 @@
+using System;
+
+namespace MQTTnet.Core.Diagnostics
+{
+    public sealed class MqttNetTraceMessage
+    {
+        public MqttNetTraceMessage(DateTime timestamp, int threadId, string source, MqttNetTraceLevel level, string message, Exception exception)
+        {
+            Timestamp = timestamp;
+            ThreadId = threadId;
+            Source = source;
+            Level = level;
+            Message = message;
+            Exception = exception;
+        }
+
+        public DateTime Timestamp { get; }
+
+        public int ThreadId { get; }
+
+        public string Source { get; }
+
+        public MqttNetTraceLevel Level { get; }
+
+        public string Message { get; }
+
+        public Exception Exception { get; }
+    }
+}

MQTTnet.Core/Diagnostics/MqttNetTraceMessagePublishedEventArgs.cs

@@ -4,23 +4,11 @@ namespace MQTTnet.Core.Diagnostics
 {
     public sealed class MqttNetTraceMessagePublishedEventArgs : EventArgs
     {
-        public MqttNetTraceMessagePublishedEventArgs(int threadId, string source, MqttNetTraceLevel level, string message, Exception exception)
+        public MqttNetTraceMessagePublishedEventArgs(MqttNetTraceMessage traceMessage)
         {
-            ThreadId = threadId;
+            TraceMessage = traceMessage ?? throw new ArgumentNullException(nameof(traceMessage));
-            Source = source;
-            Level = level;
-            Message = message;
-            Exception = exception;
         }
 
-        public int ThreadId { get; }
+        public MqttNetTraceMessage TraceMessage { get; }
-
-        public string Source { get; }
-
-        public MqttNetTraceLevel Level { get; }
-
-        public string Message { get; }
-
-        public Exception Exception { get; }
     }
 }

MQTTnet.Core/ManagedClient/ManagedMqttClient.cs

@@ -4,6 +4,7 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.Core.Client;
+using MQTTnet.Core.Diagnostics;
 using MQTTnet.Core.Exceptions;
 using MQTTnet.Core.Packets;
 
@@ -14,36 +15,23 @@ namespace MQTTnet.Core.ManagedClient
         private readonly List<MqttApplicationMessage> _messageQueue = new List<MqttApplicationMessage>();
         private readonly AutoResetEvent _messageQueueGate = new AutoResetEvent(false);
         private readonly MqttClient _mqttClient;
+        private readonly MqttNetTrace _trace;
 
         private IManagedMqttClientOptions _options;
         
-        public ManagedMqttClient(IMqttCommunicationAdapterFactory communicationChannelFactory)
+        public ManagedMqttClient(IMqttCommunicationAdapterFactory communicationChannelFactory, MqttNetTrace trace)
         {
             if (communicationChannelFactory == null) throw new ArgumentNullException(nameof(communicationChannelFactory));
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
 
-            _mqttClient = new MqttClient(communicationChannelFactory);
+            _mqttClient = new MqttClient(communicationChannelFactory, _trace);
             _mqttClient.Connected += OnConnected;
             _mqttClient.Disconnected += OnDisconnected;
             _mqttClient.ApplicationMessageReceived += OnApplicationMessageReceived;
         }
 
-        private void OnApplicationMessageReceived(object sender, MqttApplicationMessageReceivedEventArgs e)
-        {
-            ApplicationMessageReceived?.Invoke(this, e);
-        }
-
-        private void OnDisconnected(object sender, MqttClientDisconnectedEventArgs eventArgs)
-        {
-            //Disconnected?.Invoke(this, e);
-        }
-
-        private void OnConnected(object sender, EventArgs e)
-        {
-            Connected?.Invoke(this, e);
-        }
-
         public event EventHandler Connected;
-        public event EventHandler Disconnected;
+        public event EventHandler<MqttClientDisconnectedEventArgs> Disconnected;
         public event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
 
         public bool IsConnected => _mqttClient.IsConnected;
@@ -51,6 +39,9 @@ namespace MQTTnet.Core.ManagedClient
 
         public void Start(IManagedMqttClientOptions options)
         {
+            if (options == null) throw new ArgumentNullException(nameof(options));
+            if (options.ClientOptions == null) throw new ArgumentException("The client options are not set.", nameof(options));
+
 
         }
 
@@ -90,6 +81,8 @@ namespace MQTTnet.Core.ManagedClient
 
         public void Enqueue(IEnumerable<MqttApplicationMessage> applicationMessages)
         {
+            if (applicationMessages == null) throw new ArgumentNullException(nameof(applicationMessages));
+
             ThrowIfNotConnected();
 
             _messageQueue.AddRange(applicationMessages);
@@ -152,5 +145,20 @@ namespace MQTTnet.Core.ManagedClient
             //    MqttNetTrace.Information(nameof(MqttClient), "Stopped sending packets.");
             //}
         }
+
+        private void OnApplicationMessageReceived(object sender, MqttApplicationMessageReceivedEventArgs eventArgs)
+        {
+            ApplicationMessageReceived?.Invoke(this, eventArgs);
+        }
+
+        private void OnDisconnected(object sender, MqttClientDisconnectedEventArgs eventArgs)
+        {
+            Disconnected?.Invoke(this, eventArgs);
+        }
+
+        private void OnConnected(object sender, EventArgs eventArgs)
+        {
+            Connected?.Invoke(this, eventArgs);
+        }
     }
 }

MQTTnet.Core/ManagedClient/ManagedMqttClientMessagesManager.cs

@@ -1,82 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Threading.Tasks;
-using MQTTnet.Core.Diagnostics;
-
-namespace MQTTnet.Core.ManagedClient
-{
-    public class ManagedMqttClientMessagesManager
-    {
-        private readonly IList<MqttApplicationMessage> _persistedMessages = new List<MqttApplicationMessage>();
-        private readonly ManagedMqttClientOptions _options;
-
-        public ManagedMqttClientMessagesManager(ManagedMqttClientOptions options)
-        {
-            _options = options ?? throw new ArgumentNullException(nameof(options));
-        }
-
-        public async Task LoadMessagesAsync()
-        {
-            try
-            {
-                var persistentMessages = await _options.Storage.LoadQueuedMessagesAsync();
-                lock (_persistedMessages)
-                {
-                    _persistedMessages.Clear();
-                    foreach (var persistentMessage in persistentMessages)
-                    {
-                        _persistedMessages.Add(persistentMessage);
-                    }
-                }
-            }
-            catch (Exception exception)
-            {
-                MqttNetTrace.Error(nameof(ManagedMqttClientMessagesManager), exception, "Unhandled exception while loading persistent messages.");
-            }
-        }
-
-        public async Task SaveMessageAsync(MqttApplicationMessage applicationMessage)
-        {
-            if (applicationMessage != null)
-            {
-                lock (_persistedMessages)
-                {
-                    _persistedMessages.Add(applicationMessage);
-                }
-            }
-            try
-            {               
-                if (_options.Storage != null)
-                {
-                    await _options.Storage.SaveQueuedMessagesAsync(_persistedMessages);
-                }
-            }
-            catch (Exception exception)
-            {
-                MqttNetTrace.Error(nameof(ManagedMqttClientMessagesManager), exception, "Unhandled exception while saving persistent messages.");
-            }
-        }
-
-        public List<MqttApplicationMessage> GetMessages()
-        {
-            var persistedMessages = new List<MqttApplicationMessage>();
-            lock (_persistedMessages)
-            {
-                foreach (var persistedMessage in _persistedMessages)
-                {
-                    persistedMessages.Add(persistedMessage);
-                }
-            }
-
-            return persistedMessages;
-        }
-
-        public async Task Remove(MqttApplicationMessage message)
-        {
-            lock (_persistedMessages)
-                _persistedMessages.Remove(message);
-
-            await SaveMessageAsync(null);
-        }
-    }
-}

MQTTnet.Core/MqttApplicationMessageBuilder.cs

@@ -0,0 +1,108 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using MQTTnet.Core.Exceptions;
+using MQTTnet.Core.Protocol;
+
+namespace MQTTnet.Core
+{
+    public class MqttApplicationMessageBuilder
+    {
+        private MqttQualityOfServiceLevel _qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce;
+        private string _topic;
+        private byte[] _payload;
+        private bool _retain;
+        
+        public MqttApplicationMessageBuilder WithTopic(string topic)
+        {
+            _topic = topic;
+            return this;
+        }
+
+        public MqttApplicationMessageBuilder WithPayload(IEnumerable<byte> payload)
+        {
+            if (payload == null)
+            {
+                _payload = null;
+                return this;
+            }
+
+            _payload = payload.ToArray();
+            return this;
+        }
+
+        public MqttApplicationMessageBuilder WithPayload(MemoryStream payload)
+        {
+            if (payload == null)
+            {
+                _payload = null;
+                return this;
+            }
+
+            if (payload.Length == 0)
+            {
+                _payload = new byte[0];
+            }
+            else
+            {
+                _payload = new byte[payload.Length - payload.Position];
+                payload.Read(_payload, 0, _payload.Length);
+            }
+
+            return this;
+        }
+
+        public MqttApplicationMessageBuilder WithPayload(string payload)
+        {
+            if (payload == null)
+            {
+                _payload = null;
+                return this;
+            }
+
+            _payload = string.IsNullOrEmpty(payload) ? new byte[0] : Encoding.UTF8.GetBytes(payload);
+            return this;
+        }
+
+        public MqttApplicationMessageBuilder WithQualityOfServiceLevel(MqttQualityOfServiceLevel qualityOfServiceLevel)
+        {
+            _qualityOfServiceLevel = qualityOfServiceLevel;
+            return this;
+        }
+
+        public MqttApplicationMessageBuilder WithRetainFlag(bool value = true)
+        {
+            _retain = value;
+            return this;
+        }
+
+        public MqttApplicationMessageBuilder WithAtLeastOnceQoS()
+        {
+            _qualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce;
+            return this;
+        }
+
+        public MqttApplicationMessageBuilder WithAtMostOnceQoS()
+        {
+            _qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce;
+            return this;
+        }
+
+        public MqttApplicationMessageBuilder WithExactlyOnceQoS()
+        {
+            _qualityOfServiceLevel = MqttQualityOfServiceLevel.ExactlyOnce;
+            return this;
+        }
+
+        public MqttApplicationMessage Build()
+        {
+            if (string.IsNullOrEmpty(_topic))
+            {
+                throw new MqttProtocolViolationException("Topic is not set.");
+            }
+
+            return new MqttApplicationMessage(_topic, _payload ?? new byte[0], _qualityOfServiceLevel, _retain);
+        }
+    }
+}

MQTTnet.Core/MqttApplicationMessageFactory.cs

@@ -1,51 +0,0 @@
-using System;
-using System.Globalization;
-using System.IO;
-using System.Text;
-using MQTTnet.Core.Protocol;
-
-namespace MQTTnet.Core
-{
-    public class MqttApplicationMessageFactory
-    {
-        public MqttApplicationMessage CreateApplicationMessage(string topic, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce, bool retain = false)
-        {
-            if (topic == null) throw new ArgumentNullException(nameof(topic));
-
-            if (payload == null)
-            {
-                payload = new byte[0];
-            }
-
-            return new MqttApplicationMessage(topic, payload, qualityOfServiceLevel, retain);
-        }
-
-        public MqttApplicationMessage CreateApplicationMessage<TPayload>(string topic, TPayload payload, MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce, bool retain = false)
-        {
-            if (topic == null) throw new ArgumentNullException(nameof(topic));
-
-            var payloadString = Convert.ToString(payload, CultureInfo.InvariantCulture);
-            var payloadBuffer = string.IsNullOrEmpty(payloadString) ? new byte[0] : Encoding.UTF8.GetBytes(payloadString);
-
-            return CreateApplicationMessage(topic, payloadBuffer, qualityOfServiceLevel, retain);
-        }
-
-        public MqttApplicationMessage CreateApplicationMessage(string topic, Stream payload, MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce, bool retain = false)
-        {
-            if (topic == null) throw new ArgumentNullException(nameof(topic));
-
-            byte[] payloadBuffer;
-            if (payload == null || payload.Length == 0)
-            {
-                payloadBuffer = new byte[0];
-            }
-            else
-            {
-                payloadBuffer = new byte[payload.Length - payload.Position];
-                payload.Read(payloadBuffer, 0, payloadBuffer.Length);
-            }
-
-            return CreateApplicationMessage(topic, payloadBuffer, qualityOfServiceLevel, retain);
-        }
-    }
-}

MQTTnet.Core/Server/IMqttServerFactory.cs

@@ -1,7 +1,9 @@
-namespace MQTTnet.Core.Server
+using MQTTnet.Core.Diagnostics;
+
+namespace MQTTnet.Core.Server
 {
     public interface IMqttServerFactory
     {
-        IMqttServer CreateMqttServer(MqttServerOptions options);
+        IMqttServer CreateMqttServer(MqttServerOptions options, IMqttNetTraceHandler traceHandler = null);
     }
 }

MQTTnet.Core/Server/MqttClientPendingMessagesQueue.cs

@@ -15,9 +15,11 @@ namespace MQTTnet.Core.Server
         private readonly BlockingCollection<MqttPublishPacket> _pendingPublishPackets = new BlockingCollection<MqttPublishPacket>();
         private readonly MqttClientSession _session;
         private readonly MqttServerOptions _options;
+        private readonly MqttNetTrace _trace;
 
-        public MqttClientPendingMessagesQueue(MqttServerOptions options, MqttClientSession session)
+        public MqttClientPendingMessagesQueue(MqttServerOptions options, MqttClientSession session, MqttNetTrace trace)
         {
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
             _session = session ?? throw new ArgumentNullException(nameof(session));
             _options = options ?? throw new ArgumentNullException(nameof(options));
         }
@@ -50,7 +52,7 @@ namespace MQTTnet.Core.Server
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttClientPendingMessagesQueue), exception, "Unhandled exception while sending pending publish packets.");
+                _trace.Error(nameof(MqttClientPendingMessagesQueue), exception, "Unhandled exception while sending pending publish packets.");
             }
         }
 
@@ -66,18 +68,18 @@ namespace MQTTnet.Core.Server
             {
                 if (exception is MqttCommunicationTimedOutException)
                 {
-                    MqttNetTrace.Warning(nameof(MqttClientPendingMessagesQueue), exception, "Sending publish packet failed due to timeout.");
+                    _trace.Warning(nameof(MqttClientPendingMessagesQueue), exception, "Sending publish packet failed due to timeout.");
                 }
                 else if (exception is MqttCommunicationException)
                 {
-                    MqttNetTrace.Warning(nameof(MqttClientPendingMessagesQueue), exception, "Sending publish packet failed due to communication exception.");
+                    _trace.Warning(nameof(MqttClientPendingMessagesQueue), exception, "Sending publish packet failed due to communication exception.");
                 }
                 if (exception is OperationCanceledException)
                 {
                 }
                 else
                 {
-                    MqttNetTrace.Error(nameof(MqttClientPendingMessagesQueue), exception, "Sending publish packet failed.");
+                    _trace.Error(nameof(MqttClientPendingMessagesQueue), exception, "Sending publish packet failed.");
                 }
 
                 if (packet.QualityOfServiceLevel > MqttQualityOfServiceLevel.AtMostOnce)

MQTTnet.Core/Server/MqttClientRetainedMessagesManager.cs

@@ -10,11 +10,13 @@ namespace MQTTnet.Core.Server
 {
     public sealed class MqttClientRetainedMessagesManager
     {
+        private readonly MqttNetTrace _trace;
         private readonly Dictionary<string, MqttPublishPacket> _retainedMessages = new Dictionary<string, MqttPublishPacket>();
         private readonly MqttServerOptions _options;
 
-        public MqttClientRetainedMessagesManager(MqttServerOptions options)
+        public MqttClientRetainedMessagesManager(MqttServerOptions options, MqttNetTrace trace)
         {
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
             _options = options ?? throw new ArgumentNullException(nameof(options));
         }
 
@@ -39,7 +41,7 @@ namespace MQTTnet.Core.Server
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttClientRetainedMessagesManager), exception, "Unhandled exception while loading retained messages.");
+                _trace.Error(nameof(MqttClientRetainedMessagesManager), exception, "Unhandled exception while loading retained messages.");
             }
         }
 
@@ -53,12 +55,12 @@ namespace MQTTnet.Core.Server
                 if (publishPacket.Payload?.Any() == false)
                 {
                     _retainedMessages.Remove(publishPacket.Topic);
-                    MqttNetTrace.Information(nameof(MqttClientRetainedMessagesManager), "Client '{0}' cleared retained message for topic '{1}'.", clientId, publishPacket.Topic);
+                    _trace.Information(nameof(MqttClientRetainedMessagesManager), "Client '{0}' cleared retained message for topic '{1}'.", clientId, publishPacket.Topic);
                 }
                 else
                 {
                     _retainedMessages[publishPacket.Topic] = publishPacket;
-                    MqttNetTrace.Information(nameof(MqttClientRetainedMessagesManager), "Client '{0}' updated retained message for topic '{1}'.", clientId, publishPacket.Topic);
+                    _trace.Information(nameof(MqttClientRetainedMessagesManager), "Client '{0}' updated retained message for topic '{1}'.", clientId, publishPacket.Topic);
                 }
 
                 allRetainedMessages = new List<MqttPublishPacket>(_retainedMessages.Values);
@@ -74,7 +76,7 @@ namespace MQTTnet.Core.Server
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttClientRetainedMessagesManager), exception, "Unhandled exception while saving retained messages.");
+                _trace.Error(nameof(MqttClientRetainedMessagesManager), exception, "Unhandled exception while saving retained messages.");
             }
         }
 

MQTTnet.Core/Server/MqttClientSession.cs

@@ -20,17 +20,19 @@ namespace MQTTnet.Core.Server
         private readonly MqttClientSessionsManager _mqttClientSessionsManager;
         private readonly MqttClientPendingMessagesQueue _pendingMessagesQueue;
         private readonly MqttServerOptions _options;
+        private readonly MqttNetTrace _trace;
 
         private IMqttCommunicationAdapter _adapter;
         private CancellationTokenSource _cancellationTokenSource;
         private MqttApplicationMessage _willMessage;
 
-        public MqttClientSession(string clientId, MqttServerOptions options, MqttClientSessionsManager mqttClientSessionsManager)
+        public MqttClientSession(string clientId, MqttServerOptions options, MqttClientSessionsManager mqttClientSessionsManager, MqttNetTrace trace)
         {
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
             ClientId = clientId;
             _options = options ?? throw new ArgumentNullException(nameof(options));
             _mqttClientSessionsManager = mqttClientSessionsManager ?? throw new ArgumentNullException(nameof(mqttClientSessionsManager));
-            _pendingMessagesQueue = new MqttClientPendingMessagesQueue(options, this);
+            _pendingMessagesQueue = new MqttClientPendingMessagesQueue(options, this, trace);
         }
 
         public string ClientId { get; }
@@ -58,11 +60,11 @@ namespace MQTTnet.Core.Server
             }
             catch (MqttCommunicationException exception)
             {
-                MqttNetTrace.Warning(nameof(MqttClientSession), exception, "Client '{0}': Communication exception while processing client packets.", ClientId);
+                _trace.Warning(nameof(MqttClientSession), exception, "Client '{0}': Communication exception while processing client packets.", ClientId);
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttClientSession), exception, "Client '{0}': Unhandled exception while processing client packets.", ClientId);
+                _trace.Error(nameof(MqttClientSession), exception, "Client '{0}': Unhandled exception while processing client packets.", ClientId);
             }
         }
 
@@ -79,7 +81,7 @@ namespace MQTTnet.Core.Server
 
             _adapter = null;
 
-            MqttNetTrace.Information(nameof(MqttClientSession), "Client '{0}': Disconnected.", ClientId);
+            _trace.Information(nameof(MqttClientSession), "Client '{0}': Disconnected.", ClientId);
         }
 
         public void EnqueuePublishPacket(MqttPublishPacket publishPacket)
@@ -92,7 +94,7 @@ namespace MQTTnet.Core.Server
             }
 
             _pendingMessagesQueue.Enqueue(publishPacket);
-            MqttNetTrace.Verbose(nameof(MqttClientSession), "Client '{0}': Enqueued pending publish packet.", ClientId);
+            _trace.Verbose(nameof(MqttClientSession), "Client '{0}': Enqueued pending publish packet.", ClientId);
         }
 
         public void Dispose()
@@ -116,12 +118,12 @@ namespace MQTTnet.Core.Server
             }
             catch (MqttCommunicationException exception)
             {
-                MqttNetTrace.Warning(nameof(MqttClientSession), exception, "Client '{0}': Communication exception while processing client packets.", ClientId);
+                _trace.Warning(nameof(MqttClientSession), exception, "Client '{0}': Communication exception while processing client packets.", ClientId);
                 Stop();
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttClientSession), exception, "Client '{0}': Unhandled exception while processing client packets.", ClientId);
+                _trace.Error(nameof(MqttClientSession), exception, "Client '{0}': Unhandled exception while processing client packets.", ClientId);
                 Stop();
             }
         }
@@ -163,7 +165,7 @@ namespace MQTTnet.Core.Server
             }
             else
             {
-                MqttNetTrace.Warning(nameof(MqttClientSession), "Client '{0}': Received not supported packet ({1}). Closing connection.", ClientId, packet);
+                _trace.Warning(nameof(MqttClientSession), "Client '{0}': Received not supported packet ({1}). Closing connection.", ClientId, packet);
                 Stop();
             }
         }

MQTTnet.Core/Server/MqttClientSessionsManager.cs

@@ -17,11 +17,13 @@ namespace MQTTnet.Core.Server
     {
         private readonly Dictionary<string, MqttClientSession> _clientSessions = new Dictionary<string, MqttClientSession>();
         private readonly MqttServerOptions _options;
+        private readonly MqttNetTrace _trace;
 
-        public MqttClientSessionsManager(MqttServerOptions options)
+        public MqttClientSessionsManager(MqttServerOptions options, MqttNetTrace trace)
         {
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
             _options = options ?? throw new ArgumentNullException(nameof(options));
-            RetainedMessagesManager = new MqttClientRetainedMessagesManager(options);
+            RetainedMessagesManager = new MqttClientRetainedMessagesManager(options, trace);
         }
 
         public event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
@@ -74,7 +76,7 @@ namespace MQTTnet.Core.Server
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttServer), exception, exception.Message);
+                _trace.Error(nameof(MqttServer), exception, exception.Message);
             }
             finally
             {
@@ -124,7 +126,7 @@ namespace MQTTnet.Core.Server
             }
             catch (Exception exception)
             {
-                MqttNetTrace.Error(nameof(MqttClientSessionsManager), exception, "Error while processing application message");
+                _trace.Error(nameof(MqttClientSessionsManager), exception, "Error while processing application message");
             }
 
             lock (_clientSessions)
@@ -158,11 +160,11 @@ namespace MQTTnet.Core.Server
                         _clientSessions.Remove(connectPacket.ClientId);
                         clientSession.Dispose();
                         clientSession = null;
-                        MqttNetTrace.Verbose(nameof(MqttClientSessionsManager), "Disposed existing session of client '{0}'.", connectPacket.ClientId);
+                        _trace.Verbose(nameof(MqttClientSessionsManager), "Disposed existing session of client '{0}'.", connectPacket.ClientId);
                     }
                     else
                     {
-                        MqttNetTrace.Verbose(nameof(MqttClientSessionsManager), "Reusing existing session of client '{0}'.", connectPacket.ClientId);
+                        _trace.Verbose(nameof(MqttClientSessionsManager), "Reusing existing session of client '{0}'.", connectPacket.ClientId);
                     }
                 }
 
@@ -171,10 +173,10 @@ namespace MQTTnet.Core.Server
                 {
                     isExistingSession = false;
 
-                    clientSession = new MqttClientSession(connectPacket.ClientId, _options, this);
+                    clientSession = new MqttClientSession(connectPacket.ClientId, _options, this, _trace);
                     _clientSessions[connectPacket.ClientId] = clientSession;
 
-                    MqttNetTrace.Verbose(nameof(MqttClientSessionsManager), "Created a new session for client '{0}'.", connectPacket.ClientId);
+                    _trace.Verbose(nameof(MqttClientSessionsManager), "Created a new session for client '{0}'.", connectPacket.ClientId);
                 }
 
                 return new GetOrCreateClientSessionResult { IsExistingSession = isExistingSession, Session = clientSession };

MQTTnet.Core/Server/MqttServer.cs

@@ -10,18 +10,20 @@ namespace MQTTnet.Core.Server
 {
     public sealed class MqttServer : IMqttServer
     {
+        private readonly MqttNetTrace _trace;
         private readonly MqttClientSessionsManager _clientSessionsManager;
         private readonly ICollection<IMqttServerAdapter> _adapters;
         private readonly MqttServerOptions _options;
 
         private CancellationTokenSource _cancellationTokenSource;
 
-        public MqttServer(MqttServerOptions options, ICollection<IMqttServerAdapter> adapters)
+        public MqttServer(MqttServerOptions options, ICollection<IMqttServerAdapter> adapters, MqttNetTrace trace)
         {
+            _trace = trace ?? throw new ArgumentNullException(nameof(trace));
             _options = options ?? throw new ArgumentNullException(nameof(options));
             _adapters = adapters ?? throw new ArgumentNullException(nameof(adapters));
 
-            _clientSessionsManager = new MqttClientSessionsManager(options);
+            _clientSessionsManager = new MqttClientSessionsManager(options, trace);
             _clientSessionsManager.ApplicationMessageReceived += (s, e) => ApplicationMessageReceived?.Invoke(s, e);
             _clientSessionsManager.ClientConnected += OnClientConnected;
             _clientSessionsManager.ClientDisconnected += OnClientDisconnected;
@@ -57,7 +59,7 @@ namespace MQTTnet.Core.Server
                 await adapter.StartAsync(_options);
             }
 
-            MqttNetTrace.Information(nameof(MqttServer), "Started.");
+            _trace.Information(nameof(MqttServer), "Started.");
         }
 
         public async Task StopAsync()
@@ -74,7 +76,7 @@ namespace MQTTnet.Core.Server
 
             _clientSessionsManager.Clear();
 
-            MqttNetTrace.Information(nameof(MqttServer), "Stopped.");
+            _trace.Information(nameof(MqttServer), "Stopped.");
         }
 
         private void OnClientAccepted(object sender, MqttServerAdapterClientAcceptedEventArgs eventArgs)
@@ -84,13 +86,13 @@ namespace MQTTnet.Core.Server
 
         private void OnClientConnected(object sender, MqttClientConnectedEventArgs eventArgs)
         {
-            MqttNetTrace.Information(nameof(MqttServer), "Client '{0}': Connected.", eventArgs.Client.ClientId);
+            _trace.Information(nameof(MqttServer), "Client '{0}': Connected.", eventArgs.Client.ClientId);
             ClientConnected?.Invoke(this, eventArgs);
         }
 
         private void OnClientDisconnected(object sender, MqttClientDisconnectedEventArgs eventArgs)
         {
-            MqttNetTrace.Information(nameof(MqttServer), "Client '{0}': Disconnected.", eventArgs.Client.ClientId);
+            _trace.Information(nameof(MqttServer), "Client '{0}': Disconnected.", eventArgs.Client.ClientId);
             ClientDisconnected?.Invoke(this, eventArgs);
         }
     }

MQTTnet.sln

@@ -25,6 +25,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Build", "Build", "{67C28AC1
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{B3F60ECB-45BA-4C66-8903-8BB89CA67998}"
 	ProjectSection(SolutionItems) = preProject
+		LICENSE = LICENSE
 		README.md = README.md
 	EndProjectSection
 EndProject

README.md

@@ -6,7 +6,7 @@
 [![BCH compliance](https://bettercodehub.com/edge/badge/chkr1011/MQTTnet?branch=master)](https://bettercodehub.com/)
 
 # MQTTnet
-MQTTnet is a .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker). The implementation is based on the documentation from http://mqtt.org/.
+MQTTnet is a high performance .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker). The implementation is based on the documentation from http://mqtt.org/.
 
 # Features
 
@@ -18,7 +18,7 @@ MQTTnet is a .NET library for MQTT based communication. It provides a MQTT clien
 * Performance optimized (processing ~27.000 messages / second)*
 * Interfaces included for mocking and testing
 * Access to internal trace messages
-* Unit tested (62+ tests)
+* Unit tested (67+ tests)
 
 \* Tested on local machine with MQTTnet client and server running in the same process using the TCP channel. The app for verification is part of this repository and stored in _/Tests/MQTTnet.TestApp.NetFramework_.
 
@@ -62,3 +62,25 @@ This library is used in the following projects:
 * Wirehome (Open Source Home Automation system for .NET, https://github.com/chkr1011/Wirehome)
 
 If you use this library and want to see your project here please let me know.
+
+# MIT License
+
+Copyright (c) 2017 Christian Kratky
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Tests/MQTTnet.Core.Tests/MqttApplicationMessageBuilderTests.cs

@@ -0,0 +1,61 @@
+using System;
+using System.IO;
+using System.Text;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Core.Protocol;
+
+namespace MQTTnet.Core.Tests
+{
+    [TestClass]
+    public class MqttApplicationMessageBuilderTests
+    {
+        [TestMethod]
+        public void CreateApplicationMessage_TopicOnly()
+        {
+            var message = new MqttApplicationMessageBuilder().WithTopic("Abc").Build();
+            Assert.AreEqual("Abc", message.Topic);
+            Assert.IsFalse(message.Retain);
+            Assert.AreEqual(MqttQualityOfServiceLevel.AtMostOnce, message.QualityOfServiceLevel);
+        }
+
+        [TestMethod]
+        public void CreateApplicationMessage_TimeStampPayload()
+        {
+            var message = new MqttApplicationMessageBuilder().WithTopic("xyz").WithPayload(TimeSpan.FromSeconds(360).ToString()).Build();
+            Assert.AreEqual("xyz", message.Topic);
+            Assert.IsFalse(message.Retain);
+            Assert.AreEqual(MqttQualityOfServiceLevel.AtMostOnce, message.QualityOfServiceLevel);
+            Assert.AreEqual(Encoding.UTF8.GetString(message.Payload), "00:06:00");
+        }
+
+        [TestMethod]
+        public void CreateApplicationMessage_StreamPayload()
+        {
+            var stream = new MemoryStream(Encoding.UTF8.GetBytes("xHello")) { Position = 1 };
+
+            var message = new MqttApplicationMessageBuilder().WithTopic("123").WithPayload(stream).Build();
+            Assert.AreEqual("123", message.Topic);
+            Assert.IsFalse(message.Retain);
+            Assert.AreEqual(MqttQualityOfServiceLevel.AtMostOnce, message.QualityOfServiceLevel);
+            Assert.AreEqual(Encoding.UTF8.GetString(message.Payload), "Hello");
+        }
+
+        [TestMethod]
+        public void CreateApplicationMessage_Retained()
+        {
+            var message = new MqttApplicationMessageBuilder().WithTopic("lol").WithRetainFlag().Build();
+            Assert.AreEqual("lol", message.Topic);
+            Assert.IsTrue(message.Retain);
+            Assert.AreEqual(MqttQualityOfServiceLevel.AtMostOnce, message.QualityOfServiceLevel);
+        }
+
+        [TestMethod]
+        public void CreateApplicationMessage_QosLevel2()
+        {
+            var message = new MqttApplicationMessageBuilder().WithTopic("rofl").WithRetainFlag().WithQualityOfServiceLevel(MqttQualityOfServiceLevel.ExactlyOnce).Build();
+            Assert.AreEqual("rofl", message.Topic);
+            Assert.IsTrue(message.Retain);
+            Assert.AreEqual(MqttQualityOfServiceLevel.ExactlyOnce, message.QualityOfServiceLevel);
+        }
+    }
+}

Tests/MQTTnet.Core.Tests/MqttApplicationMessageFactoryTests.cs

@@ -1,30 +0,0 @@
-using System;
-using System.Text;
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Core.Protocol;
-
-namespace MQTTnet.Core.Tests
-{
-    [TestClass]
-    public class MqttApplicationMessageFactoryTests
-    {
-        [TestMethod]
-        public void CreateApplicationMessage_TopicOnly()
-        {
-            var message = new MqttApplicationMessageFactory().CreateApplicationMessage("Abc", MqttQualityOfServiceLevel.AtLeastOnce);
-            Assert.AreEqual("Abc", message.Topic);
-            Assert.IsFalse(message.Retain);
-            Assert.AreEqual(MqttQualityOfServiceLevel.AtLeastOnce, message.QualityOfServiceLevel);
-        }
-
-        [TestMethod]
-        public void CreateApplicationMessage_TimeStampPayload()
-        {
-            var message = new MqttApplicationMessageFactory().CreateApplicationMessage("xyz", TimeSpan.FromSeconds(360));
-            Assert.AreEqual("xyz", message.Topic);
-            Assert.IsFalse(message.Retain);
-            Assert.AreEqual(MqttQualityOfServiceLevel.AtMostOnce, message.QualityOfServiceLevel);
-            Assert.AreEqual(Encoding.UTF8.GetString(message.Payload), "00:06:00");
-        }
-    }
-}

Tests/MQTTnet.Core.Tests/MqttServerTests.cs

@@ -3,6 +3,7 @@ using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Core.Adapter;
 using MQTTnet.Core.Client;
+using MQTTnet.Core.Diagnostics;
 using MQTTnet.Core.Packets;
 using MQTTnet.Core.Protocol;
 using MQTTnet.Core.Server;
@@ -49,7 +50,7 @@ namespace MQTTnet.Core.Tests
         public async Task MqttServer_WillMessage()
         {
             var serverAdapter = new TestMqttServerAdapter();
-            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter });
+            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter }, new MqttNetTrace());
             await s.StartAsync();
 
             var willMessage = new MqttApplicationMessage("My/last/will", new byte[0], MqttQualityOfServiceLevel.AtMostOnce, false);
@@ -73,7 +74,7 @@ namespace MQTTnet.Core.Tests
         public async Task MqttServer_Unsubscribe()
         {
             var serverAdapter = new TestMqttServerAdapter();
-            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter });
+            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter }, new MqttNetTrace());
             await s.StartAsync();
 
             var c1 = await serverAdapter.ConnectTestClient(s, "c1");
@@ -109,7 +110,7 @@ namespace MQTTnet.Core.Tests
         public async Task MqttServer_Publish()
         {
             var serverAdapter = new TestMqttServerAdapter();
-            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter });
+            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter }, new MqttNetTrace());
             await s.StartAsync();
 
             var c1 = await serverAdapter.ConnectTestClient(s, "c1");
@@ -132,7 +133,7 @@ namespace MQTTnet.Core.Tests
         public async Task MqttServer_NoRetainedMessage()
         {
             var serverAdapter = new TestMqttServerAdapter();
-            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter });
+            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter }, new MqttNetTrace());
             await s.StartAsync();
 
             var c1 = await serverAdapter.ConnectTestClient(s, "c1");
@@ -155,7 +156,7 @@ namespace MQTTnet.Core.Tests
         public async Task MqttServer_RetainedMessage()
         {
             var serverAdapter = new TestMqttServerAdapter();
-            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter });
+            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter }, new MqttNetTrace());
             await s.StartAsync();
 
             var c1 = await serverAdapter.ConnectTestClient(s, "c1");
@@ -178,7 +179,7 @@ namespace MQTTnet.Core.Tests
         public async Task MqttServer_ClearRetainedMessage()
         {
             var serverAdapter = new TestMqttServerAdapter();
-            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter });
+            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter }, new MqttNetTrace());
             await s.StartAsync();
 
             var c1 = await serverAdapter.ConnectTestClient(s, "c1");
@@ -204,7 +205,7 @@ namespace MQTTnet.Core.Tests
             var storage = new TestStorage();
 
             var serverAdapter = new TestMqttServerAdapter();
-            var s = new MqttServer(new MqttServerOptions { Storage = storage }, new List<IMqttServerAdapter> { serverAdapter });
+            var s = new MqttServer(new MqttServerOptions { Storage = storage }, new List<IMqttServerAdapter> { serverAdapter }, new MqttNetTrace());
             await s.StartAsync();
 
             var c1 = await serverAdapter.ConnectTestClient(s, "c1");
@@ -213,7 +214,7 @@ namespace MQTTnet.Core.Tests
 
             await s.StopAsync();
 
-            s = new MqttServer(new MqttServerOptions { Storage = storage }, new List<IMqttServerAdapter> { serverAdapter });
+            s = new MqttServer(new MqttServerOptions { Storage = storage }, new List<IMqttServerAdapter> { serverAdapter }, new MqttNetTrace());
             await s.StartAsync();
 
             var c2 = await serverAdapter.ConnectTestClient(s, "c2");
@@ -235,7 +236,7 @@ namespace MQTTnet.Core.Tests
             public Task SaveRetainedMessagesAsync(IList<MqttApplicationMessage> messages)
             {
                 _messages = messages;
-                return Task.FromResult(0);
+                return Task.CompletedTask;
             }
 
             public Task<IList<MqttApplicationMessage>> LoadRetainedMessagesAsync()
@@ -252,7 +253,7 @@ namespace MQTTnet.Core.Tests
             int expectedReceivedMessagesCount)
         {
             var serverAdapter = new TestMqttServerAdapter();
-            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter });
+            var s = new MqttServer(new MqttServerOptions(), new List<IMqttServerAdapter> { serverAdapter }, new MqttNetTrace());
             await s.StartAsync();
 
             var c1 = await serverAdapter.ConnectTestClient(s, "c1");

Tests/MQTTnet.Core.Tests/TestMqttServerAdapter.cs

@@ -3,6 +3,7 @@ using System.Threading.Tasks;
 using MQTTnet.Core.Adapter;
 using MQTTnet.Core.Server;
 using MQTTnet.Core.Client;
+using MQTTnet.Core.Diagnostics;
 
 namespace MQTTnet.Core.Tests
 {
@@ -17,7 +18,7 @@ namespace MQTTnet.Core.Tests
             adapterA.Partner = adapterB;
             adapterB.Partner = adapterA;
 
-            var client = new MqttClient(new MqttCommunicationAdapterFactory(adapterA));
+            var client = new MqttClient(new MqttCommunicationAdapterFactory(adapterA), new MqttNetTrace());
             var connected = WaitForClientToConnect(server, clientId);
 
             FireClientAcceptedEvent(adapterB);

Tests/MQTTnet.TestApp.NetCore/Program.cs

@@ -45,10 +45,10 @@ namespace MQTTnet.TestApp.NetCore
         {
             MqttNetTrace.TraceMessagePublished += (s, e) =>
             {
-                Console.WriteLine($">> [{DateTime.Now:O}] [{e.ThreadId}] [{e.Source}] [{e.Level}]: {e.Message}");
+                Console.WriteLine($">> [{e.TraceMessage.Timestamp:O}] [{e.TraceMessage.ThreadId}] [{e.TraceMessage.Source}] [{e.TraceMessage.Level}]: {e.TraceMessage.Message}");
-                if (e.Exception != null)
+                if (e.TraceMessage.Exception != null)
                 {
-                    Console.WriteLine(e.Exception);
+                    Console.WriteLine(e.TraceMessage.Exception);
                 }
             };
 
@@ -134,10 +134,10 @@ namespace MQTTnet.TestApp.NetCore
         {
             MqttNetTrace.TraceMessagePublished += (s, e) =>
             {
-                Console.WriteLine($">> [{e.ThreadId}] [{e.Source}] [{e.Level}]: {e.Message}");
+                Console.WriteLine($">> [{e.TraceMessage.Timestamp:O}] [{e.TraceMessage.ThreadId}] [{e.TraceMessage.Source}] [{e.TraceMessage.Level}]: {e.TraceMessage.Message}");
-                if (e.Exception != null)
+                if (e.TraceMessage.Exception != null)
                 {
-                    Console.WriteLine(e.Exception);
+                    Console.WriteLine(e.TraceMessage.Exception);
                 }
             };
 
@@ -162,11 +162,11 @@ namespace MQTTnet.TestApp.NetCore
                 options.Storage = new RetainedMessageHandler();
 
 
-                var certificate = new X509Certificate(@"C:\certs\test\test.cer", "");
+                //var certificate = new X509Certificate(@"C:\certs\test\test.cer", "");
-                options.TlsEndpointOptions.Certificate = certificate.Export(X509ContentType.Cert);
+                //options.TlsEndpointOptions.Certificate = certificate.Export(X509ContentType.Cert);
-                options.ConnectionBacklog = 5;
+                //options.ConnectionBacklog = 5;
-                options.DefaultEndpointOptions.IsEnabled = true;
+                //options.DefaultEndpointOptions.IsEnabled = true;
-                options.TlsEndpointOptions.IsEnabled = false;
+                //options.TlsEndpointOptions.IsEnabled = false;
 
                 var mqttServer = new MqttServerFactory().CreateMqttServer(options);
                 mqttServer.ClientDisconnected += (s, e) =>
@@ -189,6 +189,51 @@ namespace MQTTnet.TestApp.NetCore
             Console.ReadLine();
             return Task.FromResult(0);
         }
+
+        // ReSharper disable once UnusedMember.Local
+        private static async void WikiCode()
+        {
+            {
+                var client = new MqttClientFactory().CreateMqttClient(new CustomTraceHandler("Client 1"));
+
+                var message = new MqttApplicationMessageBuilder()
+                    .WithTopic("MyTopic")
+                    .WithPayload("Hello World")
+                    .WithExactlyOnceQoS()
+                    .WithRetainFlag()
+                    .Build();
+
+                await client.PublishAsync(message);
+            }
+
+            {
+                var message = new MqttApplicationMessageBuilder()
+                    .WithTopic("/MQTTnet/is/awesome")
+                    .Build();
+            }
+        }
+    }
+
+    public class CustomTraceHandler : IMqttNetTraceHandler
+    {
+        private readonly string _clientId;
+
+        public CustomTraceHandler(string clientId)
+        {
+            _clientId = clientId;
+        }
+
+        public bool IsEnabled { get; } = true;
+
+        public void HandleTraceMessage(MqttNetTraceMessage traceMessage)
+        {
+            // Client ID is added to the trace message.
+            Console.WriteLine($">> [{_clientId}] [{traceMessage.Timestamp:O}] [{traceMessage.ThreadId}] [{traceMessage.Source}] [{traceMessage.Level}]: {traceMessage.Message}");
+            if (traceMessage.Exception != null)
+            {
+                Console.WriteLine(traceMessage.Exception);
+            }
+        }
     }
 
     public class RetainedMessageHandler : IMqttServerStorage

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

@@ -29,10 +29,10 @@ namespace MQTTnet.TestApp.UniversalWindows
         {
             await Trace.Dispatcher.RunAsync(CoreDispatcherPriority.High, () =>
             {
-                var text = $"[{DateTime.Now:yyyy-MM-dd HH:mm:ss.fff}] [{e.Level}] [{e.Source}] [{e.ThreadId}] [{e.Message}]{Environment.NewLine}";
+                var text = $"[{e.TraceMessage.Timestamp:yyyy-MM-dd HH:mm:ss.fff}] [{e.TraceMessage.Level}] [{e.TraceMessage.Source}] [{e.TraceMessage.ThreadId}] [{e.TraceMessage.Message}]{Environment.NewLine}";
-                if (e.Exception != null)
+                if (e.TraceMessage.Exception != null)
                 {
-                    text += $"{e.Exception}{Environment.NewLine}";
+                    text += $"{e.TraceMessage.Exception}{Environment.NewLine}";
                 }
 
                 Trace.Text += text;