Merge branch 'feature/server-project-bootstrap' into develop

Source/MQTTnet.AspnetCore/ApplicationBuilderExtensions.cs

@@ -30,8 +30,7 @@ namespace MQTTnet.AspNetCore
                 var adapter = app.ApplicationServices.GetRequiredService<MqttWebSocketServerAdapter>();
                 using (var webSocket = await context.WebSockets.AcceptWebSocketAsync(subProtocol))
                 {
-                    var endpoint = $"{context.Connection.RemoteIpAddress}:{context.Connection.RemotePort}";
-                    await adapter.RunWebSocketConnectionAsync(webSocket, endpoint);
+                    await adapter.RunWebSocketConnectionAsync(webSocket, context);
                 }
             });
 

Source/MQTTnet.AspnetCore/MqttConnectionContext.cs

@@ -20,6 +20,7 @@ namespace MQTTnet.AspNetCore
         }
 
         public string Endpoint => Connection.ConnectionId;
+        public bool IsSecureConnection => false; // TODO: Fix detection.
         public ConnectionContext Connection { get; }
         public MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
         public event EventHandler ReadingPacketStarted;

Source/MQTTnet.AspnetCore/MqttConnectionHandler.cs

@@ -10,7 +10,7 @@ namespace MQTTnet.AspNetCore
 {
     public class MqttConnectionHandler : ConnectionHandler, IMqttServerAdapter
     {
-        public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
+        public Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
 
         public override async Task OnConnectedAsync(ConnectionContext connection)
         {
@@ -24,9 +24,9 @@ namespace MQTTnet.AspNetCore
             using (var adapter = new MqttConnectionContext(new MqttPacketFormatterAdapter(), connection))
             {
                 var args = new MqttServerAdapterClientAcceptedEventArgs(adapter);
-                ClientAccepted?.Invoke(this, args);
+                ClientAcceptedHandler?.Invoke(args);
 
-                await args.SessionTask;
+                await args.SessionTask.ConfigureAwait(false);
             }
         }
 

Source/MQTTnet.AspnetCore/MqttWebSocketServerAdapter.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Net.WebSockets;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;
@@ -11,7 +12,16 @@ namespace MQTTnet.AspNetCore
 {
     public class MqttWebSocketServerAdapter : IMqttServerAdapter
     {
-        public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
+        private readonly IMqttNetChildLogger _logger;
+
+        public MqttWebSocketServerAdapter(IMqttNetChildLogger logger)
+        {
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
+            _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
+        }
+
+        public Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
 
         public Task StartAsync(IMqttServerOptions options)
         {
@@ -23,14 +33,21 @@ namespace MQTTnet.AspNetCore
             return Task.CompletedTask;
         }
 
-        public async Task RunWebSocketConnectionAsync(WebSocket webSocket, string endpoint)
+        public async Task RunWebSocketConnectionAsync(WebSocket webSocket, HttpContext httpContext)
         {
             if (webSocket == null) throw new ArgumentNullException(nameof(webSocket));
 
-            var clientAdapter = new MqttChannelAdapter(new MqttWebSocketChannel(webSocket, endpoint), new MqttPacketFormatterAdapter(), new MqttNetLogger().CreateChildLogger(nameof(MqttWebSocketServerAdapter)));
+            var endpoint = $"{httpContext.Connection.RemoteIpAddress}:{httpContext.Connection.RemotePort}";
+            
+            var clientCertificate = await httpContext.Connection.GetClientCertificateAsync().ConfigureAwait(false);
+            var isSecureConnection = clientCertificate != null;
+            clientCertificate?.Dispose();
+
+            var channel = new MqttWebSocketChannel(webSocket, endpoint, isSecureConnection);
+            var clientAdapter = new MqttChannelAdapter(channel, new MqttPacketFormatterAdapter(), _logger.CreateChildLogger(nameof(MqttWebSocketServerAdapter)));
 
             var eventArgs = new MqttServerAdapterClientAcceptedEventArgs(clientAdapter);
-            ClientAccepted?.Invoke(this, eventArgs);
+            ClientAcceptedHandler?.Invoke(eventArgs);
 
             if (eventArgs.SessionTask != null)
             {
@@ -40,7 +57,6 @@ namespace MQTTnet.AspNetCore
 
         public void Dispose()
         {
-            StopAsync().GetAwaiter().GetResult();
         }
     }
 }

Source/MQTTnet.Extensions.ManagedClient/ApplicationMessageProcessedHandlerDelegate.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Extensions.ManagedClient
+{
+    public class ApplicationMessageProcessedHandlerDelegate : IApplicationMessageProcessedHandler
+    {
+        private readonly Func<ApplicationMessageProcessedEventArgs, Task> _handler;
+
+        public ApplicationMessageProcessedHandlerDelegate(Action<ApplicationMessageProcessedEventArgs> handler)
+        {
+            if (handler == null) throw new ArgumentNullException(nameof(handler));
+
+            _handler = context =>
+            {
+                handler(context);
+                return Task.FromResult(0);
+            };
+        }
+
+        public ApplicationMessageProcessedHandlerDelegate(Func<ApplicationMessageProcessedEventArgs, Task> handler)
+        {
+            _handler = handler ?? throw new ArgumentNullException(nameof(handler));
+        }
+
+        public Task HandleApplicationMessageProcessedAsync(ApplicationMessageProcessedEventArgs eventArgs)
+        {
+            return _handler(eventArgs);
+        }
+    }
+}

Source/MQTTnet.Extensions.ManagedClient/ApplicationMessageSkippedHandlerDelegate.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Extensions.ManagedClient
+{
+    public class ApplicationMessageSkippedHandlerDelegate : IApplicationMessageSkippedHandler
+    {
+        private readonly Func<ApplicationMessageSkippedEventArgs, Task> _handler;
+
+        public ApplicationMessageSkippedHandlerDelegate(Action<ApplicationMessageSkippedEventArgs> handler)
+        {
+            if (handler == null) throw new ArgumentNullException(nameof(handler));
+
+            _handler = eventArgs =>
+            {
+                handler(eventArgs);
+                return Task.FromResult(0);
+            };
+        }
+
+        public ApplicationMessageSkippedHandlerDelegate(Func<ApplicationMessageSkippedEventArgs, Task> handler)
+        {
+            _handler = handler ?? throw new ArgumentNullException(nameof(handler));
+        }
+
+        public Task HandleApplicationMessageSkippedAsync(ApplicationMessageSkippedEventArgs eventArgs)
+        {
+            return _handler(eventArgs);
+        }
+    }
+}

Source/MQTTnet.Extensions.ManagedClient/ConnectingFailedHandlerDelegate.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Extensions.ManagedClient
+{
+    public class ConnectingFailedHandlerDelegate : IConnectingFailedHandler
+    {
+        private readonly Func<ManagedProcessFailedEventArgs, Task> _handler;
+
+        public ConnectingFailedHandlerDelegate(Action<ManagedProcessFailedEventArgs> handler)
+        {
+            if (handler == null) throw new ArgumentNullException(nameof(handler));
+
+            _handler = eventArgs =>
+            {
+                handler(eventArgs);
+                return Task.FromResult(0);
+            };
+        }
+
+        public ConnectingFailedHandlerDelegate(Func<ManagedProcessFailedEventArgs, Task> handler)
+        {
+            _handler = handler ?? throw new ArgumentNullException(nameof(handler));
+        }
+
+        public Task HandleConnectingFailedAsync(ManagedProcessFailedEventArgs eventArgs)
+        {
+            return _handler(eventArgs);
+        }
+    }
+}

Source/MQTTnet.Extensions.ManagedClient/IApplicationMessageProcessedHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace MQTTnet.Extensions.ManagedClient
+{
+    public interface IApplicationMessageProcessedHandler
+    {
+        Task HandleApplicationMessageProcessedAsync(ApplicationMessageProcessedEventArgs eventArgs);
+    }
+}

Source/MQTTnet.Extensions.ManagedClient/IApplicationMessageSkippedHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace MQTTnet.Extensions.ManagedClient
+{
+    public interface IApplicationMessageSkippedHandler
+    {
+        Task HandleApplicationMessageSkippedAsync(ApplicationMessageSkippedEventArgs eventArgs);
+    }
+}

Source/MQTTnet.Extensions.ManagedClient/IConnectingFailedHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace MQTTnet.Extensions.ManagedClient
+{
+    public interface IConnectingFailedHandler
+    {
+        Task HandleConnectingFailedAsync(ManagedProcessFailedEventArgs eventArgs);
+    }
+}

Source/MQTTnet.Extensions.ManagedClient/IManagedMqttClient.cs

@@ -14,19 +14,14 @@ namespace MQTTnet.Extensions.ManagedClient
         IManagedMqttClientOptions Options { get; }
 
         IMqttClientConnectedHandler ConnectedHandler { get; set; }
-        [Obsolete("Use ConnectedHandler instead.")]
-        event EventHandler<MqttClientConnectedEventArgs> Connected;
-
         IMqttClientDisconnectedHandler DisconnectedHandler { get; set; }
-        [Obsolete("Use DisconnectedHandler instead.")]
-        event EventHandler<MqttClientDisconnectedEventArgs> Disconnected;
 
-        event EventHandler<ApplicationMessageProcessedEventArgs> ApplicationMessageProcessed;
-        event EventHandler<ApplicationMessageSkippedEventArgs> ApplicationMessageSkipped;
-
-        event EventHandler<MqttManagedProcessFailedEventArgs> ConnectingFailed;
-        event EventHandler<MqttManagedProcessFailedEventArgs> SynchronizingSubscriptionsFailed;
+        IApplicationMessageProcessedHandler ApplicationMessageProcessedHandler { get; set; }
+        IApplicationMessageSkippedHandler ApplicationMessageSkippedHandler { get; set; }
 
+        IConnectingFailedHandler ConnectingFailedHandler { get; set; }
+        ISynchronizingSubscriptionsFailedHandler SynchronizingSubscriptionsFailedHandler { get; set; }
+        
         Task StartAsync(IManagedMqttClientOptions options);
         Task StopAsync();
 

Source/MQTTnet.Extensions.ManagedClient/IManagedMqttClientOptions.cs

@@ -1,5 +1,4 @@
 using System;
-using MQTTnet.Client;
 using MQTTnet.Client.Options;
 using MQTTnet.Server;
 

Source/MQTTnet.Extensions.ManagedClient/ISynchronizingSubscriptionsFailedHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace MQTTnet.Extensions.ManagedClient
+{
+    public interface ISynchronizingSubscriptionsFailedHandler
+    {
+        Task HandleSynchronizingSubscriptionsFailedAsync(ManagedProcessFailedEventArgs eventArgs);
+    }
+}

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs

@@ -13,8 +13,6 @@ using MQTTnet.Exceptions;
 using MQTTnet.Internal;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
-using MqttClientConnectedEventArgs = MQTTnet.Client.Connecting.MqttClientConnectedEventArgs;
-using MqttClientDisconnectedEventArgs = MQTTnet.Client.Disconnecting.MqttClientDisconnectedEventArgs;
 
 namespace MQTTnet.Extensions.ManagedClient
 {
@@ -36,14 +34,9 @@ namespace MQTTnet.Extensions.ManagedClient
 
         public ManagedMqttClient(IMqttClient mqttClient, IMqttNetChildLogger logger)
         {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
-
             _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
 
-            _mqttClient.UseConnectedHandler(OnConnected);
-            _mqttClient.UseDisconnectedHandler(OnDisconnected);
-            _mqttClient.UseReceivedApplicationMessageHandler(OnApplicationMessageReceived);
-
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
             _logger = logger.CreateChildLogger(nameof(ManagedMqttClient));
         }
 
@@ -52,25 +45,31 @@ namespace MQTTnet.Extensions.ManagedClient
         public int PendingApplicationMessagesCount => _messageQueue.Count;
         public IManagedMqttClientOptions Options { get; private set; }
 
-        public IMqttClientConnectedHandler ConnectedHandler { get; set; }
-        public event EventHandler<MqttClientConnectedEventArgs> Connected;
-
-        public IMqttClientDisconnectedHandler DisconnectedHandler { get; set; }
-        public event EventHandler<MqttClientDisconnectedEventArgs> Disconnected;
-
-
-        public IMqttApplicationMessageHandler ReceivedApplicationMessageHandler
+        public IMqttClientConnectedHandler ConnectedHandler
         {
-            get => _mqttClient.ReceivedApplicationMessageHandler;
-            set => _mqttClient.ReceivedApplicationMessageHandler = value;
+            get => _mqttClient.ConnectedHandler;
+            set => _mqttClient.ConnectedHandler = value;
         }
 
-        public event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
-        public event EventHandler<ApplicationMessageProcessedEventArgs> ApplicationMessageProcessed;
-        public event EventHandler<ApplicationMessageSkippedEventArgs> ApplicationMessageSkipped;
+        public IMqttClientDisconnectedHandler DisconnectedHandler
+        {
+            get => _mqttClient.DisconnectedHandler;
+            set => _mqttClient.DisconnectedHandler = value;
+        }
 
-        public event EventHandler<MqttManagedProcessFailedEventArgs> ConnectingFailed;
-        public event EventHandler<MqttManagedProcessFailedEventArgs> SynchronizingSubscriptionsFailed;
+        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler
+        {
+            get => _mqttClient.ApplicationMessageReceivedHandler;
+            set => _mqttClient.ApplicationMessageReceivedHandler = value;
+        }
+
+        public IApplicationMessageProcessedHandler ApplicationMessageProcessedHandler { get; set; }
+
+        public IApplicationMessageSkippedHandler ApplicationMessageSkippedHandler { get; set; }
+
+        public IConnectingFailedHandler ConnectingFailedHandler { get; set; }
+
+        public ISynchronizingSubscriptionsFailedHandler SynchronizingSubscriptionsFailedHandler { get; set; }
 
         public async Task StartAsync(IManagedMqttClientOptions options)
         {
@@ -129,28 +128,45 @@ namespace MQTTnet.Extensions.ManagedClient
             if (applicationMessage == null) throw new ArgumentNullException(nameof(applicationMessage));
 
             ManagedMqttApplicationMessage removedMessage = null;
-            lock (_messageQueue)
+            ApplicationMessageSkippedEventArgs applicationMessageSkippedEventArgs = null;
+
+            try
             {
-                if (_messageQueue.Count >= Options.MaxPendingMessages)
+                lock (_messageQueue)
                 {
-                    if (Options.PendingMessagesOverflowStrategy == MqttPendingMessagesOverflowStrategy.DropNewMessage)
+                    if (_messageQueue.Count >= Options.MaxPendingMessages)
                     {
-                        _logger.Verbose("Skipping publish of new application message because internal queue is full.");
-                        ApplicationMessageSkipped?.Invoke(this, new ApplicationMessageSkippedEventArgs(applicationMessage));
-                        return;
+                        if (Options.PendingMessagesOverflowStrategy == MqttPendingMessagesOverflowStrategy.DropNewMessage)
+                        {
+                            _logger.Verbose("Skipping publish of new application message because internal queue is full.");
+                            applicationMessageSkippedEventArgs = new ApplicationMessageSkippedEventArgs(applicationMessage);
+                            return;
+                        }
+
+                        if (Options.PendingMessagesOverflowStrategy == MqttPendingMessagesOverflowStrategy.DropOldestQueuedMessage)
+                        {
+                            removedMessage = _messageQueue.RemoveFirst();
+                            _logger.Verbose("Removed oldest application message from internal queue because it is full.");
+                            applicationMessageSkippedEventArgs = new ApplicationMessageSkippedEventArgs(removedMessage);
+                        }
                     }
 
-                    if (Options.PendingMessagesOverflowStrategy == MqttPendingMessagesOverflowStrategy.DropOldestQueuedMessage)
+                    _messageQueue.Enqueue(applicationMessage);
+                }
+            }
+            finally
+            {
+                if (applicationMessageSkippedEventArgs != null)
+                {
+                    var applicationMessageSkippedHandler = ApplicationMessageSkippedHandler;
+                    if (applicationMessageSkippedHandler != null)
                     {
-                        removedMessage = _messageQueue.RemoveFirst();
-                        _logger.Verbose("Removed oldest application message from internal queue because it is full.");
-                        ApplicationMessageSkipped?.Invoke(this, new ApplicationMessageSkippedEventArgs(removedMessage));
+                        await applicationMessageSkippedHandler.HandleApplicationMessageSkippedAsync(applicationMessageSkippedEventArgs).ConfigureAwait(false);
                     }
                 }
 
-                _messageQueue.Enqueue(applicationMessage);
             }
-
+            
             if (_storageManager != null)
             {
                 if (removedMessage != null)
@@ -355,7 +371,7 @@ namespace MQTTnet.Extensions.ManagedClient
             }
             finally
             {
-                ApplicationMessageProcessed?.Invoke(this, new ApplicationMessageProcessedEventArgs(message, transmitException));
+                ApplicationMessageProcessedHandler?.HandleApplicationMessageProcessedAsync(new ApplicationMessageProcessedEventArgs(message, transmitException)).GetAwaiter().GetResult();
             }
         }
 
@@ -398,7 +414,11 @@ namespace MQTTnet.Extensions.ManagedClient
                 _logger.Warning(exception, "Synchronizing subscriptions failed.");
                 _subscriptionsNotPushed = true;
 
-                SynchronizingSubscriptionsFailed?.Invoke(this, new MqttManagedProcessFailedEventArgs(exception));
+                var synchronizingSubscriptionsFailedHandler = SynchronizingSubscriptionsFailedHandler;
+                if (SynchronizingSubscriptionsFailedHandler != null)
+                {
+                    await synchronizingSubscriptionsFailedHandler.HandleSynchronizingSubscriptionsFailedAsync(new ManagedProcessFailedEventArgs(exception)).ConfigureAwait(false);
+                }
             }
         }
 
@@ -416,29 +436,16 @@ namespace MQTTnet.Extensions.ManagedClient
             }
             catch (Exception exception)
             {
-                ConnectingFailed?.Invoke(this, new MqttManagedProcessFailedEventArgs(exception));
+                var connectingFailedHandler = ConnectingFailedHandler;
+                if (connectingFailedHandler != null)
+                {
+                    await connectingFailedHandler.HandleConnectingFailedAsync(new ManagedProcessFailedEventArgs(exception)).ConfigureAwait(false);
+                }
+
                 return ReconnectionResult.NotConnected;
             }
         }
-
-        private Task OnApplicationMessageReceived(MqttApplicationMessageHandlerContext context)
-        {
-            ApplicationMessageReceived?.Invoke(this, new MqttApplicationMessageReceivedEventArgs(context.SenderClientId, context.ApplicationMessage));
-            return Task.FromResult(0);
-        }
-
-        private Task OnDisconnected(MqttClientDisconnectedEventArgs eventArgs)
-        {
-            Disconnected?.Invoke(this, eventArgs);
-            return DisconnectedHandler?.HandleDisconnectedAsync(eventArgs);
-        }
-
-        private Task OnConnected(MqttClientConnectedEventArgs eventArgs)
-        {
-            Connected?.Invoke(this, eventArgs);
-            return ConnectedHandler?.HandleConnectedAsync(eventArgs);
-        }
-
+        
         private void StartPublishing()
         {
             if (_publishingCancellationToken != null)

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClientExtensions.cs

@@ -60,28 +60,28 @@ namespace MQTTnet.Extensions.ManagedClient
             return client;
         }
 
-        public static IManagedMqttClient UseReceivedApplicationMessageHandler(this IManagedMqttClient client, Func<MqttApplicationMessageHandlerContext, Task> handler)
+        public static IManagedMqttClient UseApplicationMessageReceivedHandler(this IManagedMqttClient client, Func<MqttApplicationMessageReceivedEventArgs, Task> handler)
         {
             if (handler == null)
             {
-                client.ReceivedApplicationMessageHandler = null;
+                client.ApplicationMessageReceivedHandler = null;
                 return client;
             }
 
-            client.ReceivedApplicationMessageHandler = new MqttApplicationMessageHandlerDelegate(handler);
+            client.ApplicationMessageReceivedHandler = new MqttApplicationMessageReceivedHandlerDelegate(handler);
 
             return client;
         }
 
-        public static IManagedMqttClient UseReceivedApplicationMessageHandler(this IManagedMqttClient client, Action<MqttApplicationMessageHandlerContext> handler)
+        public static IManagedMqttClient UseApplicationMessageReceivedHandler(this IManagedMqttClient client, Action<MqttApplicationMessageReceivedEventArgs> handler)
         {
             if (handler == null)
             {
-                client.ReceivedApplicationMessageHandler = null;
+                client.ApplicationMessageReceivedHandler = null;
                 return client;
             }
 
-            client.ReceivedApplicationMessageHandler = new MqttApplicationMessageHandlerDelegate(handler);
+            client.ApplicationMessageReceivedHandler = new MqttApplicationMessageReceivedHandlerDelegate(handler);
 
             return client;
         }

Source/MQTTnet.Extensions.ManagedClient/ManagedProcessFailedEventArgs.cs

@@ -2,9 +2,9 @@
 
 namespace MQTTnet.Extensions.ManagedClient
 {
-    public class MqttManagedProcessFailedEventArgs : EventArgs
+    public class ManagedProcessFailedEventArgs : EventArgs
     {
-        public MqttManagedProcessFailedEventArgs(Exception exception)
+        public ManagedProcessFailedEventArgs(Exception exception)
         {
             Exception = exception;
         }

Source/MQTTnet.Extensions.ManagedClient/MqttFactoryExtensions.cs

@@ -1,19 +1,18 @@
 using System;
-using MQTTnet.Client;
 using MQTTnet.Diagnostics;
 
 namespace MQTTnet.Extensions.ManagedClient
 {
     public static class MqttFactoryExtensions
     {
-        public static IManagedMqttClient CreateManagedMqttClient(this IMqttClientFactory factory)
+        public static IManagedMqttClient CreateManagedMqttClient(this IMqttFactory factory)
         {
             if (factory == null) throw new ArgumentNullException(nameof(factory));
 
-            return new ManagedMqttClient(factory.CreateMqttClient(), new MqttNetLogger().CreateChildLogger());
+            return new ManagedMqttClient(factory.CreateMqttClient(), factory.DefaultLogger.CreateChildLogger());
         }
 
-        public static IManagedMqttClient CreateManagedMqttClient(this IMqttClientFactory factory, IMqttNetLogger logger)
+        public static IManagedMqttClient CreateManagedMqttClient(this IMqttFactory factory, IMqttNetLogger logger)
         {
             if (factory == null) throw new ArgumentNullException(nameof(factory));
             if (logger == null) throw new ArgumentNullException(nameof(logger));

Source/MQTTnet.Extensions.ManagedClient/SynchronizingSubscriptionsFailedHandlerDelegate.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Extensions.ManagedClient
+{
+    public class SynchronizingSubscriptionsFailedHandlerDelegate : ISynchronizingSubscriptionsFailedHandler
+    {
+        private readonly Func<ManagedProcessFailedEventArgs, Task> _handler;
+
+        public SynchronizingSubscriptionsFailedHandlerDelegate(Action<ManagedProcessFailedEventArgs> handler)
+        {
+            if (handler == null) throw new ArgumentNullException(nameof(handler));
+
+            _handler = context =>
+            {
+                handler(context);
+                return Task.FromResult(0);
+            };
+        }
+
+        public SynchronizingSubscriptionsFailedHandlerDelegate(Func<ManagedProcessFailedEventArgs, Task> handler)
+        {
+            _handler = handler ?? throw new ArgumentNullException(nameof(handler));
+        }
+
+        public Task HandleSynchronizingSubscriptionsFailedAsync(ManagedProcessFailedEventArgs eventArgs)
+        {
+            return _handler(eventArgs);
+        }
+    }
+}

Source/MQTTnet.Extensions.Rpc/MqttRpcClient.cs

@@ -13,12 +13,17 @@ namespace MQTTnet.Extensions.Rpc
     {
         private readonly ConcurrentDictionary<string, TaskCompletionSource<byte[]>> _waitingCalls = new ConcurrentDictionary<string, TaskCompletionSource<byte[]>>();
         private readonly IMqttClient _mqttClient;
+        private readonly RpcAwareApplicationMessageReceivedHandler _applicationMessageReceivedHandler;
 
         public MqttRpcClient(IMqttClient mqttClient)
         {
             _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
 
-            _mqttClient.ApplicationMessageReceived += OnApplicationMessageReceived;
+            _applicationMessageReceivedHandler = new RpcAwareApplicationMessageReceivedHandler(
+                mqttClient.ApplicationMessageReceivedHandler,
+                HandleApplicationMessageReceivedAsync);
+
+            _mqttClient.ApplicationMessageReceivedHandler = _applicationMessageReceivedHandler;
         }
 
         public Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
@@ -45,6 +50,11 @@ namespace MQTTnet.Extensions.Rpc
                 throw new ArgumentException("The method name cannot contain /, + or #.");
             }
 
+            if (!(_mqttClient.ApplicationMessageReceivedHandler is RpcAwareApplicationMessageReceivedHandler))
+            {
+                throw new InvalidOperationException("The application message received handler was modified.");
+            }
+
             var requestTopic = $"MQTTnet.RPC/{Guid.NewGuid():N}/{methodName}";
             var responseTopic = requestTopic + "/response";
 
@@ -102,26 +112,30 @@ namespace MQTTnet.Extensions.Rpc
             }
         }
 
-        private void OnApplicationMessageReceived(object sender, MqttApplicationMessageReceivedEventArgs eventArgs)
+        private Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
         {
             if (!_waitingCalls.TryRemove(eventArgs.ApplicationMessage.Topic, out var tcs))
             {
-                return;
+                return Task.FromResult(0);
             }
 
             if (tcs.Task.IsCompleted || tcs.Task.IsCanceled)
             {
-                return;
+                return Task.FromResult(0);
             }
 
             tcs.TrySetResult(eventArgs.ApplicationMessage.Payload);
+
+            return Task.FromResult(0);
         }
 
         public void Dispose()
         {
+            _mqttClient.ApplicationMessageReceivedHandler = _applicationMessageReceivedHandler.OriginalHandler;
+
             foreach (var tcs in _waitingCalls)
             {
-                tcs.Value.SetCanceled();
+                tcs.Value.TrySetCanceled();
             }
 
             _waitingCalls.Clear();

Source/MQTTnet.Extensions.Rpc/RpcAwareApplicationMessageReceivedHandler.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+using MQTTnet.Client.Receiving;
+
+namespace MQTTnet.Extensions.Rpc
+{
+    public class RpcAwareApplicationMessageReceivedHandler : IMqttApplicationMessageReceivedHandler
+    {
+        private readonly Func<MqttApplicationMessageReceivedEventArgs, Task> _handleReceivedApplicationMessageAsync;
+
+        public RpcAwareApplicationMessageReceivedHandler(
+            IMqttApplicationMessageReceivedHandler originalHandler,
+            Func<MqttApplicationMessageReceivedEventArgs, Task> handleReceivedApplicationMessageAsync)
+        {
+            OriginalHandler = originalHandler;
+            _handleReceivedApplicationMessageAsync = handleReceivedApplicationMessageAsync ?? throw new ArgumentNullException(nameof(handleReceivedApplicationMessageAsync));
+        }
+
+        public IMqttApplicationMessageReceivedHandler OriginalHandler { get; }
+
+        public async Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs)
+        {
+            if (OriginalHandler != null)
+            {
+                await OriginalHandler.HandleApplicationMessageReceivedAsync(eventArgs).ConfigureAwait(false);
+            }
+
+            await _handleReceivedApplicationMessageAsync(eventArgs).ConfigureAwait(false);
+        }
+    }
+}

Source/MQTTnet.Server/Configuration/ListenModel.cs

@@ -0,0 +1,132 @@
+using System.IO;
+using System.Net;
+
+namespace MQTTnet.Server.Configuration
+{
+    /// <summary>
+    /// Listen Entry Settings Model
+    /// </summary>
+    public class ListenModel
+    {
+        /// <summary>
+        /// Constructor
+        /// </summary>
+        public ListenModel()
+        {
+        }
+
+        /// <summary>
+        /// Path to Certificate
+        /// </summary>
+        public string CertificatePath { get; set; }
+
+        /// <summary>
+        /// Enabled / Disable
+        /// </summary>
+        public bool Enabled { get; set; } = true;
+
+        /// <summary>
+        /// Listen Address
+        /// </summary>
+        public string IPv4 { get; set; }
+
+        /// <summary>
+        /// Listen Address
+        /// </summary>
+        public string IPv6 { get; set; }
+
+        /// <summary>
+        /// Listen Port
+        /// </summary>
+        public int Port { get; set; } = 1883;
+
+        /// <summary>
+        /// Read Certificate file
+        /// </summary>
+        /// <returns></returns>
+        public byte[] ReadCertificate()
+        {
+            if (string.IsNullOrEmpty(CertificatePath) || string.IsNullOrWhiteSpace(CertificatePath))
+            {
+                throw new FileNotFoundException("No path set");
+            }
+
+            if (!File.Exists(CertificatePath))
+            {
+                throw new FileNotFoundException($"Could not find Certificate in path: {CertificatePath}");
+            }
+
+            return File.ReadAllBytes(CertificatePath);
+        }
+
+        /// <summary>
+        /// Read IPv4
+        /// </summary>
+        /// <returns></returns>
+        public bool TryReadIPv4(out IPAddress address)
+        {
+            if (IPv4 == "*")
+            {
+                address = IPAddress.Parse("0.0.0.0");
+                return true;
+            }
+
+            if (IPv4 == "localhost")
+            {
+                address = IPAddress.Parse("127.0.0.1");
+                return true;
+            }
+
+            if (IPv4 == "disable")
+            {
+                address = IPAddress.None;
+                return true;
+            }
+
+            if (IPAddress.TryParse(IPv4, out var ip))
+            {
+                address = ip;
+                return true;
+            }
+            else
+            {
+                throw new System.Exception($"Could not parse IPv4 address: {IPv4}");
+            }
+        }
+
+        /// <summary>
+        /// Read IPv6
+        /// </summary>
+        /// <returns></returns>
+        public bool TryReadIPv6(out IPAddress address)
+        {
+            if (IPv6 == "*")
+            {
+                address = IPAddress.Parse("::");
+                return true;
+            }
+
+            if (IPv6 == "localhost")
+            {
+                address = IPAddress.Parse("::1");
+                return true;
+            }
+
+            if (IPv6 == "disable")
+            {
+                address = IPAddress.None;
+                return true;
+            }
+
+            if (IPAddress.TryParse(IPv6, out var ip))
+            {
+                address = ip;
+                return true;
+            }
+            else
+            {
+                throw new System.Exception($"Could not parse IPv6 address: {IPv6}");
+            }
+        }
+    }
+}

Source/MQTTnet.Server/Configuration/SettingsModel.cs

@@ -0,0 +1,42 @@
+namespace MQTTnet.Server.Configuration
+{
+    /// <summary>
+    /// Main Settings Model
+    /// </summary>
+    public class SettingsModel
+    {
+        public SettingsModel()
+        {
+        }
+
+        /// <summary>
+        /// Set default connection timeout in seconds
+        /// </summary>
+        public int CommunicationTimeout { get; set; } = 15;
+
+        /// <summary>
+        /// Set 0 to disable connection backlogging
+        /// </summary>
+        public int ConnectionBacklog { get; set; }
+
+        /// <summary>
+        /// Enable support for persistent sessions
+        /// </summary>
+        public bool EnablePersistentSessions { get; set; } = false;
+
+        /// <summary>
+        /// Listen Settings
+        /// </summary>
+        public ListenModel EndPoint { get; set; } = new ListenModel();
+
+        /// <summary>
+        /// Encryption Listen Settings
+        /// </summary>
+        public ListenModel EndPointEncryption { get; set; } = new ListenModel();
+
+        /// <summary>
+        /// Set limit for max pending messages per client
+        /// </summary>
+        public int MaxPendingMessagesPerClient { get; set; } = 250;
+    }
+}

Source/MQTTnet.Server/Controllers/ValuesController.cs

@@ -0,0 +1,42 @@
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Mvc;
+
+namespace MQTTnet.Server.Controllers
+{
+    [Route("api/[controller]")]
+    [ApiController]
+    public class ValuesController : ControllerBase
+    {
+        // GET api/values
+        [HttpGet]
+        public ActionResult<IEnumerable<string>> Get()
+        {
+            return new string[] { "value1", "value2" };
+        }
+
+        // GET api/values/5
+        [HttpGet("{id}")]
+        public ActionResult<string> Get(int id)
+        {
+            return "value";
+        }
+
+        // POST api/values
+        [HttpPost]
+        public void Post([FromBody] string value)
+        {
+        }
+
+        // PUT api/values/5
+        [HttpPut("{id}")]
+        public void Put(int id, [FromBody] string value)
+        {
+        }
+
+        // DELETE api/values/5
+        [HttpDelete("{id}")]
+        public void Delete(int id)
+        {
+        }
+    }
+}

Source/MQTTnet.Server/LICENSE

@@ -0,0 +1,21 @@
+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.

Source/MQTTnet.Server/Logging/MqttNetChildLoggerWrapper.cs

@@ -0,0 +1,43 @@
+using System;
+using MQTTnet.Diagnostics;
+
+namespace MQTTnet.Server.Logging
+{
+    public class MqttNetChildLoggerWrapper : IMqttNetChildLogger
+    {
+        private readonly MqttNetLoggerWrapper _logger;
+        private readonly string _source;
+
+        public MqttNetChildLoggerWrapper(string source, MqttNetLoggerWrapper logger)
+        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+
+            _source = source;
+        }
+
+        public IMqttNetChildLogger CreateChildLogger(string source = null)
+        {
+            return _logger.CreateChildLogger(source);
+        }
+
+        public void Verbose(string message, params object[] parameters)
+        {
+            _logger.Publish(MqttNetLogLevel.Verbose, _source, message, parameters, null);
+        }
+
+        public void Info(string message, params object[] parameters)
+        {
+            _logger.Publish(MqttNetLogLevel.Info, _source, message, parameters, null);
+        }
+
+        public void Warning(Exception exception, string message, params object[] parameters)
+        {
+            _logger.Publish(MqttNetLogLevel.Warning, _source, message, parameters, exception);
+        }
+
+        public void Error(Exception exception, string message, params object[] parameters)
+        {
+            _logger.Publish(MqttNetLogLevel.Error, _source, message, parameters, exception);
+        }
+    }
+}

Source/MQTTnet.Server/Logging/MqttNetLoggerWrapper.cs

@@ -0,0 +1,48 @@
+using System;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Diagnostics;
+
+namespace MQTTnet.Server.Logging
+{
+    public class MqttNetLoggerWrapper : IMqttNetLogger
+    {
+        private readonly ILogger<MqttServer> _logger;
+
+        public MqttNetLoggerWrapper(ILogger<MqttServer> logger)
+        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public event EventHandler<MqttNetLogMessagePublishedEventArgs> LogMessagePublished;
+        
+        public IMqttNetChildLogger CreateChildLogger(string source = null)
+        {
+            return new MqttNetChildLoggerWrapper(source, this);
+        }
+
+        public void Publish(MqttNetLogLevel logLevel, string source, string message, object[] parameters, Exception exception)
+        {
+            var convertedLogLevel = ConvertLogLevel(logLevel);
+
+            if (!_logger.IsEnabled(convertedLogLevel))
+            {
+                return;
+            }
+
+            _logger.Log(convertedLogLevel, exception, message, parameters);
+        }
+
+        private static LogLevel ConvertLogLevel(MqttNetLogLevel logLevel)
+        {
+            switch (logLevel)
+            {
+                case MqttNetLogLevel.Error: return LogLevel.Error;
+                case MqttNetLogLevel.Warning: return LogLevel.Warning;
+                case MqttNetLogLevel.Info: return LogLevel.Information;
+                case MqttNetLogLevel.Verbose: return LogLevel.Trace;
+            }
+
+            return LogLevel.Debug;
+        }
+    }
+}

Source/MQTTnet.Server/MQTTnet.Server.csproj

@@ -0,0 +1,83 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
+    <AssemblyName>MQTTnet.Server</AssemblyName>
+    <RootNamespace>MQTTnet.Server</RootNamespace>
+    <GeneratePackageOnBuild>False</GeneratePackageOnBuild>
+    <Company />
+    <Product>MQTTnet</Product>
+    <Description />
+    <Authors />
+    <PackageId />
+    <SignAssembly>false</SignAssembly>
+    <DelaySign>false</DelaySign>
+    <LangVersion>latest</LangVersion>
+    <TypeScriptToolsVersion>3.3</TypeScriptToolsVersion>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <StartupObject></StartupObject>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
+    <DocumentationFile></DocumentationFile>
+    <WarningsAsErrors>NU1605</WarningsAsErrors>
+    <NoWarn>1701;1702</NoWarn>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Content Remove="wwwroot\app\app.ts" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Content Update="appsettings.json">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Update="wwwroot\app\app.js">
+      <CopyToOutputDirectory>Never</CopyToOutputDirectory>
+    </Content>
+    <Content Update="wwwroot\app\app.js.map">
+      <CopyToOutputDirectory>Never</CopyToOutputDirectory>
+    </Content>
+    <Content Update="wwwroot\Index.html">
+      <CopyToOutputDirectory>Never</CopyToOutputDirectory>
+    </Content>
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="IronPython" Version="2.7.9" />
+    <PackageReference Include="IronPython.StdLib" Version="2.7.9" />
+    <PackageReference Include="Microsoft.AspNetCore.App" />
+    <PackageReference Include="Microsoft.AspNetCore.Razor.Design" Version="2.2.0" PrivateAssets="All" />
+    <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="2.2.0" />
+    <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.2.1" />
+    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerGen" Version="4.0.1" />
+    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="4.0.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\MQTTnet.AspnetCore\MQTTnet.AspNetCore.csproj" />
+    <ProjectReference Include="..\MQTTnet\MQTTnet.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Update="LICENSE">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+    <None Update="Scripts\readme.md">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+    <None Update="Scripts\00_sample.py">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+  <ItemGroup>
+    <TypeScriptCompile Include="wwwroot\app\app.ts">
+      <CopyToOutputDirectory>Never</CopyToOutputDirectory>
+    </TypeScriptCompile>
+  </ItemGroup>
+
+</Project>

Source/MQTTnet.Server/Mqtt/CustomMqttFactory.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Generic;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Adapter;
+using MQTTnet.Diagnostics;
+using MQTTnet.Server.Logging;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class CustomMqttFactory
+    {
+        private readonly MqttFactory _mqttFactory;
+
+        public CustomMqttFactory(ILogger<MqttServer> logger)
+        {
+            if (logger == null) throw new ArgumentNullException(nameof(logger));
+
+            Logger = new MqttNetLoggerWrapper(logger);
+
+            _mqttFactory = new MqttFactory(Logger);
+        }
+        
+        public IMqttNetLogger Logger { get; }
+
+        public IMqttServer CreateMqttServer(List<IMqttServerAdapter> adapters)
+        {
+            if (adapters == null) throw new ArgumentNullException(nameof(adapters));
+
+            return _mqttFactory.CreateMqttServer(adapters);
+        }
+    }
+}

Source/MQTTnet.Server/Mqtt/MqttApplicationMessageInterceptor.cs

@@ -0,0 +1,66 @@
+using System;
+using System.Threading.Tasks;
+using IronPython.Runtime;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Protocol;
+using MQTTnet.Server.Scripting;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class MqttApplicationMessageInterceptor : IMqttServerApplicationMessageInterceptor
+    {
+        private readonly PythonScriptHostService _pythonScriptHostService;
+        private readonly ILogger _logger;
+
+        public MqttApplicationMessageInterceptor(PythonScriptHostService pythonScriptHostService, ILogger<MqttApplicationMessageInterceptor> logger)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public Task InterceptApplicationMessagePublishAsync(MqttApplicationMessageInterceptorContext context)
+        {
+            try
+            {
+                var pythonContext = new PythonDictionary
+                {
+                    { "accept_publish", context.AcceptPublish },
+                    { "close_connection", context.CloseConnection },
+                    { "client_id", context.ClientId },
+                    { "topic", context.ApplicationMessage.Topic },
+                    { "qos", (int)context.ApplicationMessage.QualityOfServiceLevel },
+                    { "retain", context.ApplicationMessage.Retain }
+                };
+                
+                _pythonScriptHostService.InvokeOptionalFunction("on_intercept_application_message", pythonContext);
+
+                context.AcceptPublish = (bool)pythonContext.get("accept_publish", context.AcceptPublish);
+                context.CloseConnection = (bool)pythonContext.get("close_connection", context.CloseConnection);
+                context.ApplicationMessage.Topic = (string)pythonContext.get("topic", context.ApplicationMessage.Topic);
+                context.ApplicationMessage.QualityOfServiceLevel = (MqttQualityOfServiceLevel)(int)pythonContext.get("qos", (int)context.ApplicationMessage.QualityOfServiceLevel);
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Error while intercepting application message.");
+            }
+
+            return Task.CompletedTask;
+        }
+
+        // TODO: Create dump(object) method in wrapper (creates JSON and prints it).
+        public class PythonMqttApplicationMessageInterceptorContext
+        {
+            public bool accept_connection;
+
+            public bool accept_publish;
+
+            public string client_id;
+
+            public string topic;
+
+            public int qos;
+
+            public bool retain;
+        }
+    }
+}

Source/MQTTnet.Server/Mqtt/MqttClientConnectedHandler.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Threading.Tasks;
+using IronPython.Runtime;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Server.Scripting;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class MqttClientConnectedHandler : IMqttServerClientConnectedHandler
+    {
+        private readonly PythonScriptHostService _pythonScriptHostService;
+        private readonly ILogger _logger;
+
+        public MqttClientConnectedHandler(PythonScriptHostService pythonScriptHostService, ILogger<MqttClientConnectedHandler> logger)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public Task HandleClientConnectedAsync(MqttServerClientConnectedEventArgs eventArgs)
+        {
+            try
+            {
+                var pythonEventArgs = new PythonDictionary
+                {
+                    { "client_id", eventArgs.ClientId }
+                };
+
+                _pythonScriptHostService.InvokeOptionalFunction("on_client_connected", pythonEventArgs);
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Error while handling client connected event.");
+            }
+
+            return Task.CompletedTask;
+        }
+    }
+}

Source/MQTTnet.Server/Mqtt/MqttClientDisconnectedHandler.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Threading.Tasks;
+using IronPython.Runtime;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Server.Scripting;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class MqttClientDisconnectedHandler : IMqttServerClientDisconnectedHandler
+    {
+        private readonly PythonScriptHostService _pythonScriptHostService;
+        private readonly ILogger _logger;
+
+        public MqttClientDisconnectedHandler(PythonScriptHostService pythonScriptHostService, ILogger<MqttClientDisconnectedHandler> logger)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public Task HandleClientDisconnectedAsync(MqttServerClientDisconnectedEventArgs eventArgs)
+        {
+            try
+            {
+                var pythonEventArgs = new PythonDictionary
+                {
+                    { "client_id", eventArgs.ClientId },
+                    { "type", PythonConvert.Pythonfy(eventArgs.DisconnectType) }
+                };
+
+                _pythonScriptHostService.InvokeOptionalFunction("on_client_disconnected", pythonEventArgs);
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Error while handling client disconnected event.");
+            }
+
+            return Task.CompletedTask;
+        }
+    }
+}

Source/MQTTnet.Server/Mqtt/MqttClientSubscribedTopicHandler.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Threading.Tasks;
+using IronPython.Runtime;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Server.Scripting;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class MqttClientSubscribedTopicHandler : IMqttServerClientSubscribedTopicHandler
+    {
+        private readonly PythonScriptHostService _pythonScriptHostService;
+        private readonly ILogger _logger;
+
+        public MqttClientSubscribedTopicHandler(PythonScriptHostService pythonScriptHostService, ILogger<MqttClientSubscribedTopicHandler> logger)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public Task HandleClientSubscribedTopicAsync(MqttServerClientSubscribedTopicEventArgs eventArgs)
+        {
+            try
+            {
+                var pythonEventArgs = new PythonDictionary
+                {
+                    { "client_id", eventArgs.ClientId },
+                    { "topic", eventArgs.TopicFilter.Topic },
+                    { "qos", (int)eventArgs.TopicFilter.QualityOfServiceLevel }
+                };
+
+                _pythonScriptHostService.InvokeOptionalFunction("on_client_subscribed_topic", pythonEventArgs);
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Error while handling client subscribed topic event.");
+            }
+
+            return Task.CompletedTask;
+        }
+    }
+}

Source/MQTTnet.Server/Mqtt/MqttClientUnsubscribedTopicHandler.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Threading.Tasks;
+using IronPython.Runtime;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Server.Scripting;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class MqttClientUnsubscribedTopicHandler : IMqttServerClientUnsubscribedTopicHandler
+    {
+        private readonly PythonScriptHostService _pythonScriptHostService;
+        private readonly ILogger _logger;
+
+        public MqttClientUnsubscribedTopicHandler(PythonScriptHostService pythonScriptHostService, ILogger<MqttClientUnsubscribedTopicHandler> logger)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public Task HandleClientUnsubscribedTopicAsync(MqttServerClientUnsubscribedTopicEventArgs eventArgs)
+        {
+            try
+            {
+                var pythonEventArgs = new PythonDictionary
+                {
+                    { "client_id", eventArgs.ClientId },
+                    { "topic", eventArgs.TopicFilter }
+                };
+
+                _pythonScriptHostService.InvokeOptionalFunction("on_client_unsubscribed_topic", pythonEventArgs);
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Error while handling client unsubscribed topic event.");
+            }
+
+            return Task.CompletedTask;
+        }
+    }
+}

Source/MQTTnet.Server/Mqtt/MqttConnectionValidator.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Threading.Tasks;
+using IronPython.Runtime;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Protocol;
+using MQTTnet.Server.Scripting;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class MqttConnectionValidator : IMqttServerConnectionValidator
+    {
+        private readonly PythonScriptHostService _pythonScriptHostService;
+        private readonly ILogger _logger;
+
+        public MqttConnectionValidator(PythonScriptHostService pythonScriptHostService, ILogger<MqttConnectionValidator> logger)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public Task ValidateConnectionAsync(MqttConnectionValidatorContext context)
+        {
+            try
+            {
+                var pythonContext = new PythonDictionary
+                {
+                    { "client_id", context.ClientId },
+                    { "endpoint", context.Endpoint },
+                    { "is_secure_connection", context.IsSecureConnection },
+                    { "username", context.Username },
+                    { "password", context.Password },
+                    { "result", PythonConvert.Pythonfy(context.ReturnCode) }
+                };
+
+                _pythonScriptHostService.InvokeOptionalFunction("on_validate_client_connection", pythonContext);
+
+                context.ReturnCode = PythonConvert.ParseEnum<MqttConnectReturnCode>((string)pythonContext["result"]);
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Error while validating client connection.");
+            }
+
+            return Task.CompletedTask;
+        }
+    }
+}

Source/MQTTnet.Server/Mqtt/MqttServerService.cs

@@ -0,0 +1,191 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using IronPython.Runtime;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Adapter;
+using MQTTnet.AspNetCore;
+using MQTTnet.Implementations;
+using MQTTnet.Protocol;
+using MQTTnet.Server.Scripting;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class MqttServerService
+    {
+        private readonly ILogger<MqttServerService> _logger;
+
+        private readonly Configuration.SettingsModel _settings;
+        private readonly MqttApplicationMessageInterceptor _mqttApplicationMessageInterceptor;
+        private readonly MqttClientConnectedHandler _mqttClientConnectedHandler;
+        private readonly MqttClientDisconnectedHandler _mqttClientDisconnectedHandler;
+        private readonly MqttClientSubscribedTopicHandler _mqttClientSubscribedTopicHandler;
+        private readonly MqttClientUnsubscribedTopicHandler _mqttClientUnsubscribedTopicHandler;
+        private readonly MqttConnectionValidator _mqttConnectionValidator;
+        private readonly IMqttServer _mqttServer;
+        private readonly MqttSubscriptionInterceptor _mqttSubscriptionInterceptor;
+        private readonly PythonScriptHostService _pythonScriptHostService;
+
+        public MqttServerService(
+            Configuration.SettingsModel settings,
+            CustomMqttFactory mqttFactory,
+            MqttClientConnectedHandler mqttClientConnectedHandler,
+            MqttClientDisconnectedHandler mqttClientDisconnectedHandler,
+            MqttClientSubscribedTopicHandler mqttClientSubscribedTopicHandler,
+            MqttClientUnsubscribedTopicHandler mqttClientUnsubscribedTopicHandler,
+            MqttConnectionValidator mqttConnectionValidator,
+            MqttSubscriptionInterceptor mqttSubscriptionInterceptor,
+            MqttApplicationMessageInterceptor mqttApplicationMessageInterceptor,
+            PythonScriptHostService pythonScriptHostService,
+            ILogger<MqttServerService> logger)
+        {
+            _settings = settings;
+            _mqttClientConnectedHandler = mqttClientConnectedHandler ?? throw new ArgumentNullException(nameof(mqttClientConnectedHandler));
+            _mqttClientDisconnectedHandler = mqttClientDisconnectedHandler ?? throw new ArgumentNullException(nameof(mqttClientDisconnectedHandler));
+            _mqttClientSubscribedTopicHandler = mqttClientSubscribedTopicHandler ?? throw new ArgumentNullException(nameof(mqttClientSubscribedTopicHandler));
+            _mqttClientUnsubscribedTopicHandler = mqttClientUnsubscribedTopicHandler ?? throw new ArgumentNullException(nameof(mqttClientUnsubscribedTopicHandler));
+            _mqttConnectionValidator = mqttConnectionValidator ?? throw new ArgumentNullException(nameof(mqttConnectionValidator));
+            _mqttSubscriptionInterceptor = mqttSubscriptionInterceptor ?? throw new ArgumentNullException(nameof(mqttSubscriptionInterceptor));
+            _mqttApplicationMessageInterceptor = mqttApplicationMessageInterceptor ?? throw new ArgumentNullException(nameof(mqttApplicationMessageInterceptor));
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+
+            WebSocketServerAdapter = new MqttWebSocketServerAdapter(mqttFactory.Logger.CreateChildLogger());
+
+            var adapters = new List<IMqttServerAdapter>
+            {
+                new MqttTcpServerAdapter(mqttFactory.Logger.CreateChildLogger()),
+                WebSocketServerAdapter
+            };
+
+            _mqttServer = mqttFactory.CreateMqttServer(adapters);
+        }
+
+        public MqttWebSocketServerAdapter WebSocketServerAdapter { get; }
+
+        public void Configure()
+        {
+            _pythonScriptHostService.RegisterProxyObject("publish", new Action<PythonDictionary>(Publish));
+
+            var options = new MqttServerOptionsBuilder()
+                .WithMaxPendingMessagesPerClient(_settings.MaxPendingMessagesPerClient)
+                .WithDefaultCommunicationTimeout(TimeSpan.FromSeconds(_settings.CommunicationTimeout))
+                .WithConnectionValidator(_mqttConnectionValidator)
+                .WithApplicationMessageInterceptor(_mqttApplicationMessageInterceptor)
+                .WithSubscriptionInterceptor(_mqttSubscriptionInterceptor);
+
+            // Configure unencrypted connections
+            if (_settings.EndPoint.Enabled)
+            {
+                options.WithDefaultEndpoint();
+                if (_settings.EndPoint.TryReadIPv4(out var address4))
+                {
+                    options.WithDefaultEndpointBoundIPAddress(address4);
+                }
+
+                if (_settings.EndPoint.TryReadIPv6(out var address6))
+                {
+                    options.WithDefaultEndpointBoundIPV6Address(address6);
+                }
+
+                if (_settings.EndPoint.Port > 0)
+                {
+                    options.WithDefaultEndpointPort(_settings.EndPoint.Port);
+                }
+            }
+            else
+            {
+                options.WithoutDefaultEndpoint();
+            }
+
+            // Configure encrypted connections
+            if (_settings.EndPointEncryption.Enabled)
+            {
+                options
+                    .WithEncryptedEndpoint()
+                    .WithEncryptionSslProtocol(System.Security.Authentication.SslProtocols.Tls12)
+                    .WithEncryptionCertificate(_settings.EndPointEncryption.ReadCertificate());
+
+                if (_settings.EndPointEncryption.TryReadIPv4(out var address4))
+                {
+                    options.WithEncryptedEndpointBoundIPAddress(address4);
+                }
+
+                if (_settings.EndPointEncryption.TryReadIPv6(out var address6))
+                {
+                    options.WithEncryptedEndpointBoundIPV6Address(address6);
+                }
+
+                if (_settings.EndPoint.Port > 0)
+                {
+                    options.WithEncryptedEndpointPort(_settings.EndPointEncryption.Port);
+                }
+            }
+            else
+            {
+                options.WithoutEncryptedEndpoint();
+            }
+
+            if (_settings.ConnectionBacklog > 0)
+            {
+                options.WithConnectionBacklog(_settings.ConnectionBacklog);
+            }
+
+            _mqttServer.ClientConnectedHandler = _mqttClientConnectedHandler;
+            _mqttServer.ClientDisconnectedHandler = _mqttClientDisconnectedHandler;
+            _mqttServer.ClientSubscribedTopicHandler = _mqttClientSubscribedTopicHandler;
+            _mqttServer.ClientUnsubscribedTopicHandler = _mqttClientUnsubscribedTopicHandler;
+
+            _mqttServer.StartAsync(options.Build()).GetAwaiter().GetResult();
+
+            _logger.LogInformation("MQTT server started.");
+        }
+
+        private void Publish(PythonDictionary parameters)
+        {
+            try
+            {
+                var applicationMessageBuilder = new MqttApplicationMessageBuilder()
+                    .WithTopic((string)parameters.get("topic", null))
+                    .WithRetainFlag((bool)parameters.get("retain", false))
+                    .WithQualityOfServiceLevel((MqttQualityOfServiceLevel)(int)parameters.get("qos", 0));
+
+                var payload = parameters.get("payload", null);
+                byte[] binaryPayload;
+
+                if (payload == null)
+                {
+                    binaryPayload = new byte[0];
+                }
+                else if (payload is string stringPayload)
+                {
+                    binaryPayload = Encoding.UTF8.GetBytes(stringPayload);
+                }
+                else if (payload is ByteArray byteArray)
+                {
+                    binaryPayload = byteArray.ToArray();
+                }
+                else if (payload is IEnumerable<int> intArray)
+                {
+                    binaryPayload = intArray.Select(Convert.ToByte).ToArray();
+                }
+                else
+                {
+                    throw new NotSupportedException("Payload type not supported.");
+                }
+
+                applicationMessageBuilder = applicationMessageBuilder
+                    .WithPayload(binaryPayload);
+
+                var applicationMessage = applicationMessageBuilder.Build();
+
+                _mqttServer.PublishAsync(applicationMessage).GetAwaiter().GetResult();
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Error while publishing application message from server.");
+            }
+        }
+    }
+}

Source/MQTTnet.Server/Mqtt/MqttSubscriptionInterceptor.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Threading.Tasks;
+using IronPython.Runtime;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Server.Scripting;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class MqttSubscriptionInterceptor : IMqttServerSubscriptionInterceptor
+    {
+        private readonly PythonScriptHostService _pythonScriptHostService;
+        private readonly ILogger _logger;
+
+        public MqttSubscriptionInterceptor(PythonScriptHostService pythonScriptHostService, ILogger<MqttSubscriptionInterceptor> logger)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public Task InterceptSubscriptionAsync(MqttSubscriptionInterceptorContext context)
+        {
+            try
+            {
+                var pythonContext = new PythonDictionary
+                {
+                    { "accept_subscription", context.AcceptSubscription },
+                    { "close_connection", context.CloseConnection },
+
+                    { "client_id", context.ClientId },
+                    { "topic", context.TopicFilter.Topic },
+                    { "qos", (int)context.TopicFilter.QualityOfServiceLevel }
+                };
+
+                _pythonScriptHostService.InvokeOptionalFunction("on_intercept_subscription", pythonContext);
+
+                context.AcceptSubscription = (bool)pythonContext["accept_subscription"];
+                context.CloseConnection = (bool)pythonContext["close_connection"];
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Error while intercepting subscription.");
+            }
+
+            return Task.CompletedTask;
+        }
+    }
+}

Source/MQTTnet.Server/Program.cs

@@ -0,0 +1,67 @@
+using System;
+using Microsoft.AspNetCore;
+using Microsoft.AspNetCore.Hosting;
+
+namespace MQTTnet.Server
+{
+    public static class Program
+    {
+        public static int Main(string[] args)
+        {
+            try
+            {
+                PrintLogo();
+
+                CreateWebHostBuilder(args).Build().Run();
+                return 0;
+            }
+            catch (Exception exception)
+            {
+                Console.WriteLine(exception);
+                return -1;
+            }
+        }
+
+        private static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
+            WebHost.CreateDefaultBuilder(args)
+                  .UseKestrel()
+                  .UseStartup<Startup>();
+
+        private static void PrintLogo()
+        {
+            Console.ResetColor();
+            Console.ForegroundColor = ConsoleColor.Red;
+            Console.WriteLine(@"
+  __  __  ____ _______ _______         _      _____
+ |  \/  |/ __ \__   __|__   __|       | |    / ____|
+ | \  / | |  | | | |     | |_ __   ___| |_  | (___   ___ _ ____   _____ _ __
+ | |\/| | |  | | | |     | | '_ \ / _ \ __|  \___ \ / _ \ '__\ \ / / _ \ '__|
+ | |  | | |__| | | |     | | | | |  __/ |_   ____) |  __/ |   \ V /  __/ |
+ |_|  |_|\___\_\ |_|     |_|_| |_|\___|\__| |_____/ \___|_|    \_/ \___|_|");
+
+            Console.ForegroundColor = ConsoleColor.White;
+            Console.WriteLine(@"
+          -- The official MQTT server implementation of MQTTnet --
+                 Copyright (c) 2017-2019 The MQTTnet Team");
+
+            Console.ForegroundColor = ConsoleColor.Blue;
+            Console.WriteLine(@"
+                   https://github.com/chkr1011/MQTTnet");
+
+            Console.ForegroundColor = ConsoleColor.White;
+            Console.WriteLine(@"
+ Version:    1.0.0-alpha1
+ License:    MIT (read LICENSE file)
+ Sponsoring: https://opencollective.com/mqttnet
+ Support:    https://github.com/chkr1011/MQTTnet/issues
+ Docs:       https://github.com/chkr1011/MQTTnet/wiki/MQTTnetServer
+");
+
+            Console.BackgroundColor = ConsoleColor.White;
+            Console.ForegroundColor = ConsoleColor.Red;
+            Console.WriteLine(" ! THIS IS AN ALPHA VERSION! IT IS NOT RECOMMENDED TO USE IT FOR ANY DIFFERENT PURPOSE THAN TESTING OR EVALUATING!");
+            Console.WriteLine();
+            Console.ResetColor();
+        }
+    }
+}

Source/MQTTnet.Server/Scripting/DataSharing/DataSharingService.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using Microsoft.Extensions.Logging;
+
+namespace MQTTnet.Server.Scripting.DataSharing
+{
+    public class DataSharingService
+    {
+        private readonly Dictionary<string, object> _storage = new Dictionary<string, object>();
+        private readonly PythonScriptHostService _pythonScriptHostService;
+        private readonly ILogger<DataSharingService> _logger;
+
+        public DataSharingService(PythonScriptHostService pythonScriptHostService, ILogger<DataSharingService> logger)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public void Configure()
+        {
+            _pythonScriptHostService.RegisterProxyObject("write_shared_data", new Action<string, object>(Write));
+            _pythonScriptHostService.RegisterProxyObject("read_shared_data", new Func<string, object, object>(Read));
+        }
+
+        public void Write(string key, object value)
+        {
+            lock (_storage)
+            {
+                _storage[key] = value;
+                _logger.LogInformation($"Shared data with key '{key}' updated.");
+            }
+        }
+
+        public object Read(string key, object defaultValue)
+        {
+            lock (_storage)
+            {
+                if (!_storage.TryGetValue(key, out var value))
+                {
+                    return defaultValue;
+                }
+
+                return value;
+            }
+        }
+    }
+}

Source/MQTTnet.Server/Scripting/PythonConvert.cs

@@ -0,0 +1,88 @@
+using System;
+using System.Collections;
+using System.Text;
+using IronPython.Runtime;
+
+namespace MQTTnet.Server.Scripting
+{
+    public static class PythonConvert
+    {
+        public static object ToPython(object value)
+        {
+            if (value is PythonDictionary)
+            {
+                return value;
+            }
+
+            if (value is string)
+            {
+                return value;
+            }
+
+            if (value is int)
+            {
+                return value;
+            }
+
+            if (value is float)
+            {
+                return value;
+            }
+
+            if (value is bool)
+            {
+                return value;
+            }
+
+            if (value is IDictionary dictionary)
+            {
+                var pythonDictionary = new PythonDictionary();
+                foreach (DictionaryEntry dictionaryEntry in dictionary)
+                {
+                    pythonDictionary.Add(dictionaryEntry.Key, ToPython(dictionaryEntry.Value));
+                }
+
+                return pythonDictionary;
+            }
+
+            if (value is IEnumerable enumerable)
+            {
+                var pythonList = new List();
+                foreach (var item in enumerable)
+                {
+                    pythonList.Add(ToPython(item));
+                }
+
+                return pythonList;
+            }
+
+            return value;
+        }
+
+        public static string Pythonfy(Enum value)
+        {
+            return Pythonfy(value.ToString());
+        }
+
+        public static string Pythonfy(string value)
+        {
+            var result = new StringBuilder();
+            foreach (var @char in value)
+            {
+                if (char.IsUpper(@char) && result.Length > 0)
+                {
+                    result.Append('_');
+                }
+
+                result.Append(char.ToLowerInvariant(@char));
+            }
+
+            return result.ToString();
+        }
+
+        public static TEnum ParseEnum<TEnum>(string value) where TEnum : Enum
+        {
+            return (TEnum)Enum.Parse(typeof(TEnum), value.Replace("_", string.Empty), true);
+        }
+    }
+}

Source/MQTTnet.Server/Scripting/PythonIOStream.cs

@@ -0,0 +1,66 @@
+using System;
+using System.IO;
+using System.Text;
+using Microsoft.Extensions.Logging;
+
+namespace MQTTnet.Server.Scripting
+{
+    public class PythonIOStream : Stream
+    {
+        private readonly ILogger _logger;
+        private readonly Encoding _encoder = Encoding.UTF8;
+
+        public PythonIOStream(ILogger<PythonIOStream> logger)
+        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public override void Flush()
+        {
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            throw new NotSupportedException();
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            throw new NotSupportedException();
+        }
+
+        public override void SetLength(long value)
+        {
+            throw new NotSupportedException();
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            if (buffer == null) throw new ArgumentNullException(nameof(buffer));
+
+            if (count == 0)
+            {
+                return;
+            }
+
+            var text = _encoder.GetString(buffer, offset, count);
+            if (text.Equals(Environment.NewLine))
+            {
+                return;
+            }
+
+            _logger.LogDebug(text);
+        }
+
+        public override bool CanRead { get; } = false;
+        public override bool CanSeek { get; } = false;
+        public override bool CanWrite { get; } = true;
+        public override long Length { get; } = 0L;
+
+        public override long Position
+        {
+            get => throw new NotSupportedException();
+            set => throw new NotSupportedException();
+        }
+    }
+}

Source/MQTTnet.Server/Scripting/PythonScriptHostService.cs

@@ -0,0 +1,130 @@
+using System;
+using System.Collections.Generic;
+using System.Dynamic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using Microsoft.Extensions.Logging;
+using Microsoft.Scripting;
+using Microsoft.Scripting.Hosting;
+
+namespace MQTTnet.Server.Scripting
+{
+    public class PythonScriptHostService
+    {
+        private readonly IDictionary<string, object> _proxyObjects = new ExpandoObject();
+        private readonly List<PythonScriptInstance> _scriptInstances = new List<PythonScriptInstance>();
+        private readonly ILogger<PythonScriptHostService> _logger;
+        private readonly ScriptEngine _scriptEngine;
+        
+        public PythonScriptHostService(PythonIOStream pythonIOStream, ILogger<PythonScriptHostService> logger)
+        {
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+
+            _scriptEngine = IronPython.Hosting.Python.CreateEngine();
+            _scriptEngine.Runtime.IO.SetOutput(pythonIOStream, Encoding.UTF8);
+        }
+
+        public void Configure()
+        {
+            AddSearchPaths(_scriptEngine);
+
+            var scriptsDirectory = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Scripts");
+            foreach (var filename in Directory.GetFiles(scriptsDirectory, "*.py", SearchOption.AllDirectories).OrderBy(file => file))
+            {
+                TryInitializeScript(filename);
+            }
+        }
+
+        public void RegisterProxyObject(string name, object @object)
+        {
+            if (name == null) throw new ArgumentNullException(nameof(name));
+            if (@object == null) throw new ArgumentNullException(nameof(@object));
+
+            _proxyObjects.Add(name, @object);
+        }
+
+        public void InvokeOptionalFunction(string name, object parameters)
+        {
+            if (name == null) throw new ArgumentNullException(nameof(name));
+
+            lock (_scriptInstances)
+            {
+                foreach (var pythonScriptInstance in _scriptInstances)
+                {
+                    try
+                    {
+                        pythonScriptInstance.InvokeOptionalFunction(name, parameters);
+                    }
+                    catch (Exception exception)
+                    {
+                        _logger.LogError(exception, $"Error while invoking function '{name}' at script '{pythonScriptInstance.Name}'.");
+                    }
+                }
+            }
+        }
+
+        private void TryInitializeScript(string filename)
+        {
+            try
+            {
+                var scriptName = new FileInfo(filename).Name;
+
+                _logger.LogTrace($"Initializing Python script '{scriptName}'...");
+                var code = File.ReadAllText(filename);
+
+                var scriptInstance = CreateScriptInstance(scriptName, code);
+                scriptInstance.InvokeOptionalFunction("initialize");
+
+                _scriptInstances.Add(scriptInstance);
+
+                _logger.LogInformation($"Initialized script '{scriptName}'.");
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, $"Error while initializing script '{new FileInfo(filename).Name}'.");
+            }
+        }
+
+        private PythonScriptInstance CreateScriptInstance(string name, string code)
+        {
+            var scriptScope = _scriptEngine.CreateScope();
+
+            var source = scriptScope.Engine.CreateScriptSourceFromString(code, SourceCodeKind.File);
+            var compiledCode = source.Compile();
+
+            scriptScope.SetVariable("mqtt_net_server", _proxyObjects);
+            compiledCode.Execute(scriptScope);
+            
+            return new PythonScriptInstance(name, scriptScope);
+        }
+
+        private void AddSearchPaths(ScriptEngine scriptEngine)
+        {
+            var paths = new List<string>
+            {
+                Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Lib"),
+                "/usr/lib/python2.7",
+                @"C:\Python27\Lib"
+            };
+            
+            AddSearchPaths(scriptEngine, paths);
+        }
+
+        private void AddSearchPaths(ScriptEngine scriptEngine, IEnumerable<string> paths)
+        {
+            var searchPaths = scriptEngine.GetSearchPaths();
+
+            foreach (var path in paths)
+            {
+                if (Directory.Exists(path))
+                {
+                    searchPaths.Add(path);
+                    _logger.LogInformation($"Added Python lib path: {path}");
+                }
+            }
+
+            scriptEngine.SetSearchPaths(searchPaths);
+        }
+    }
+}

Source/MQTTnet.Server/Scripting/PythonScriptInstance.cs

@@ -0,0 +1,57 @@
+using System;
+using IronPython.Runtime;
+using Microsoft.Scripting.Hosting;
+
+namespace MQTTnet.Server.Scripting
+{
+    public class PythonScriptInstance
+    {
+        private readonly ScriptScope _scriptScope;
+
+        public PythonScriptInstance(string name, ScriptScope scriptScope)
+        {
+            _scriptScope = scriptScope;
+
+            Name = name;
+        }
+
+        public string Name { get; }
+
+        public bool InvokeOptionalFunction(string name, params object[] parameters)
+        {
+            return InvokeOptionalFunction(name, parameters, out _);
+        }
+
+        public bool InvokeOptionalFunction(string name, object[] parameters, out object result)
+        {
+            if (name == null) throw new ArgumentNullException(nameof(name));
+
+            lock (_scriptScope)
+            {
+                if (!_scriptScope.Engine.Operations.TryGetMember(_scriptScope, name, out var member))
+                {
+                    result = null;
+                    return false;
+                }
+
+                if (!(member is PythonFunction function))
+                {
+                    throw new Exception($"Member '{name}' is no Python function.");
+                }
+
+                try
+                {
+                    result = _scriptScope.Engine.Operations.Invoke(function, parameters);
+                    return true;
+                }
+                catch (Exception exception)
+                {
+                    var details = _scriptScope.Engine.GetService<ExceptionOperations>().FormatException(exception);
+                    var message = $"Error while invoking function '{name}'. " + Environment.NewLine + details;
+
+                    throw new Exception(message, exception);
+                }
+            }
+        }
+    }
+}

Source/MQTTnet.Server/Scripts/00_sample.py

@@ -0,0 +1,107 @@
+import json
+
+
+def initialize():
+    """
+    This function is invoked after the script file has been loaded.
+    It will be executed only one time.
+    """
+
+    print("Hello World from Sample script.")
+   
+
+def on_validate_client_connection(context):
+    """
+    This function is invoked whenever a client wants to connect. It can be used to validate the connection.
+    """
+    
+    print(context)
+
+    mqtt_net_server.write_shared_data(context["client_id"], {"custom_value_1": 1, "custom_value_2": True})
+
+    return
+
+    if context["client_id"] != "test_client":
+        context["result"] = "connection_refused_not_authorized"
+        return
+
+    if context["username"] != "bud spencer":
+        context["result"] = "connection_refused_not_authorized"
+        return
+
+    if context["password"] != "secret":
+        context["result"] = "connection_refused_not_authorized"
+
+    print(context)
+
+
+def on_intercept_subscription(context):
+    """
+    This function is invoked whenever a client wants to subscribe to a topic.
+    """
+    
+    print("Client '{client_id}' want's to subscribe to topic '{topic}'.".format(client_id=context["client_id"], topic=context["topic"]))
+
+
+def on_intercept_application_message(context):
+    """
+    This function is invoked for every processed application message. It also allows modifying
+    the message or cancel processing at all.
+    """
+
+    client_id = context["client_id"]
+
+    if client_id != None:
+        shared_data = mqtt_net_server.read_shared_data(context["client_id"], {})
+        print(shared_data)
+
+    if context["topic"] == "topic_with_response":
+
+        json_payload = {
+            "hello": "world",
+            "x": 1,
+            "y": True,
+            "z": None
+        }
+
+        application_message = {
+            "retain": False,
+            "topic": "reply",
+            "payload": json.dumps(json_payload)
+            }
+
+        mqtt_net_server.publish(application_message)
+
+    print("Client '{client_id}' published topic '{topic}'.".format(client_id=context["client_id"], topic=context["topic"]))
+
+
+def on_client_connected(event_args):
+    """
+    This function is called whenever a client has passed the validation is connected.
+    """
+
+    print("Client '{client_id}' is now connected.".format(client_id=event_args["client_id"]))
+
+
+def on_client_disconnected(event_args):
+    """
+    This function is called whenever a client has disconnected.
+    """
+
+    print("Client '{client_id}' is now disconnected (type = {type}).".format(client_id=event_args["client_id"], type=event_args["type"]))
+
+
+def on_client_subscribed_topic(event_args):
+    """
+    This function is called whenever a client has subscribed to a topic (when allowed).
+    """
+
+    print("Client '{client_id}' has subscribed to '{topic}'.".format(client_id=event_args["client_id"], topic=event_args["topic"]))
+
+
+def on_client_unsubscribed_topic(event_args):
+    """
+    This function is called whenever a client has unsubscribed from a topic.
+    """
+
+    print("Client '{client_id}' has unsubscribed from '{topic}'.".format(client_id=event_args["client_id"], topic=event_args["topic"]))

Source/MQTTnet.Server/Scripts/readme.md

@@ -0,0 +1,19 @@
+This directory contains scripts which are loaded by the server and can be used to perform the following tasks.
+
+1. Validation of client connections via credentials, client IDs etc.
+2. Manipulation of every processed message.
+3. Validation of subscription attempts.
+4. Publishing of custom application messages.
+
+All scripts are loaded and _MQTTnet Server_ will invoke functions according to predefined naming conventions.
+If a function is implemented in multiple scripts the context will be moved throug all instances. This allows overriding of results or passing data to other (following) scripts.
+
+The Python starndard library ships with _MQTTnet Server_. But it is possible to add custom paths with Python libraries.
+
+```
+import sys
+sys.path.append(PATH_TO_LIBRARY)
+```
+
+* All scripts must have the file extension _.py_. 
+* All scripts are sorted alphabetically (A to Z) before being loaded and parsed.

Source/MQTTnet.Server/Startup.cs

@@ -0,0 +1,110 @@
+using System;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using MQTTnet.Server.Logging;
+using MQTTnet.Server.Mqtt;
+using MQTTnet.Server.Scripting;
+using MQTTnet.Server.Scripting.DataSharing;
+
+namespace MQTTnet.Server
+{
+    public class Startup
+    {
+        public Startup(IConfiguration configuration)
+        {
+            var builder = new ConfigurationBuilder()
+                .AddJsonFile("appsettings.json")
+                .AddEnvironmentVariables();
+
+            Configuration = builder.Build();
+        }
+        
+        public IConfigurationRoot Configuration { get; }
+
+        public void Configure(
+            IApplicationBuilder application, 
+            IHostingEnvironment environment, 
+            MqttServerService mqttServerService,
+            PythonScriptHostService pythonScriptHostService,
+            DataSharingService dataSharingService)
+        {
+            if (environment.IsDevelopment())
+            {
+                application.UseDeveloperExceptionPage();
+            }
+            else
+            {
+                application.UseHsts();
+            }
+
+            application.UseStaticFiles();
+
+            var webSocketOptions = new WebSocketOptions
+            {
+                KeepAliveInterval = TimeSpan.FromSeconds(120),
+                ReceiveBufferSize = 4 * 1024
+            };
+
+            application.UseWebSockets(webSocketOptions);
+
+            application.UseHttpsRedirection();
+            application.UseMvc();
+
+            application.Use(async (context, next) =>
+            {
+                if (context.Request.Path == "/mqtt") // TODO: Full path to config.
+                {
+                    if (context.WebSockets.IsWebSocketRequest)
+                    {
+                        using (var webSocket = await context.WebSockets.AcceptWebSocketAsync().ConfigureAwait(false))
+                        {
+                            await mqttServerService.WebSocketServerAdapter.RunWebSocketConnectionAsync(webSocket, context).ConfigureAwait(false);
+                        }
+                    }
+                    else
+                    {
+                        context.Response.StatusCode = 400;
+                    }
+                }
+                else
+                {
+                    await next().ConfigureAwait(false);
+                }
+            });
+
+            dataSharingService.Configure();
+            pythonScriptHostService.Configure();
+            mqttServerService.Configure();
+        }
+
+        public void ConfigureServices(IServiceCollection services)
+        {
+            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
+
+            // Read settings
+            var settings = new Configuration.SettingsModel();
+            Configuration.Bind("MQTT", settings);
+            services.AddSingleton(settings);
+
+            // Wire up dependencies
+            services.AddSingleton<PythonIOStream>();
+            services.AddSingleton<PythonScriptHostService>();
+            services.AddSingleton<DataSharingService>();
+
+            services.AddSingleton<MqttNetLoggerWrapper>();
+            services.AddSingleton<CustomMqttFactory>();
+            services.AddSingleton<MqttServerService>();
+
+            services.AddSingleton<MqttClientConnectedHandler>();
+            services.AddSingleton<MqttClientDisconnectedHandler>();
+            services.AddSingleton<MqttClientSubscribedTopicHandler>();
+            services.AddSingleton<MqttClientUnsubscribedTopicHandler>();
+            services.AddSingleton<MqttConnectionValidator>();
+            services.AddSingleton<MqttSubscriptionInterceptor>();
+            services.AddSingleton<MqttApplicationMessageInterceptor>();
+        }
+    }
+}

Source/MQTTnet.Server/appsettings.Development.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Debug",
+      "System": "Information",
+      "Microsoft": "Information"
+    }
+  }
+}

Source/MQTTnet.Server/appsettings.json

@@ -0,0 +1,43 @@
+{
+    "Kestrel": {
+        "EndPoints": {
+            "Http": {
+                "Url": "http://localhost:80"
+            },
+            "Https": {
+                "Url": "http://localhost:443"
+            }
+        }
+    },
+    "MQTT": {
+        /*
+         Wildcard Addresses:
+          *             - All local IP addresses
+          localhost     - Localhost only
+          disable       - Skip address assignment
+        */
+        "EndPoint": {
+            "Enabled": true,
+            "IPv4": "localhost",
+            "IPv6": "localhost",
+            "Port": 1883
+        },
+        "EndPointEncryption": {
+            "Enabled": false,
+            "IPv4": "localhost",
+            "IPv6": "localhost",
+            "Port": 8883,
+            "CertificatePath": "/absolute/path/to/pfx"
+        },
+        "CommunicationTimeout": 15, /* In seconds */
+        "ConnectionBacklog": 0, /* Set 0 to disable */
+        "EnablePersistentSessions": false,
+        "MaxPendingMessagesPerClient": 250
+    },
+    "Logging": {
+        "LogLevel": {
+            "Default": "Warning"
+        }
+    },
+    "AllowedHosts": "*"
+}

Source/MQTTnet.Server/package.json

@@ -0,0 +1,12 @@
+{
+  "version": "1.0.0",
+  "name": "mqtt.test",
+  "private": true,
+  "devDependencies": {},
+  "dependencies": {
+    "@types/node": "^8.0.46",
+    "mqtt": "^2.15.1",
+    "systemjs": "^0.20.19",
+    "typescript": "^2.3.4"
+  }
+}

Source/MQTTnet.Server/tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "compilerOptions": {
+    "noImplicitAny": false,
+    "noEmitOnError": true,
+    "removeComments": false,
+    "sourceMap": true,
+    "target": "es5"
+  },
+  "exclude": [
+    "node_modules"
+  ]
+}

Source/MQTTnet.Server/wwwroot/Index.html

@@ -0,0 +1,35 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8" />
+    <title>MQTTnet Server test</title>
+</head>
+<body>
+<script src="node_modules/systemjs/dist/system.js"></script>
+<script>
+    System.config({
+        packages: {
+            '': {
+                defaultExtension: 'js'
+            }
+        },
+        map: {
+            mqtt: 'node_modules/mqtt/dist/mqtt.min'
+        }
+    });
+    System.import('app/app');
+</script>
+    
+<div>
+    <p id="state"></p>
+    <input id="topic" placeholder="topic" />
+    <input id="msg" placeholder="msg" />
+    <button id="publish">send</button>
+</div>
+
+<div>
+    <ul id="msgs" ></ul>
+</div>
+
+</body>
+</html>

Source/MQTTnet.Server/wwwroot/app/app.ts

@@ -0,0 +1,58 @@
+import { connect } from "mqtt";
+
+var client = connect('ws://' + location.host + '/mqtt',
+    {
+        clientId: "client" + Math.floor(Math.random() * 6) + 1
+    });
+
+window.onbeforeunload = () => {
+    client.end();
+};
+
+var publishButton = document.getElementById("publish");
+var topicInput = <HTMLInputElement>document.getElementById("topic");
+var msgInput = <HTMLInputElement>document.getElementById("msg");
+var stateParagraph = document.getElementById("state");
+var msgsList = <HTMLUListElement>document.getElementById("msgs");
+
+publishButton.onclick = click => {
+    var topic = topicInput.value;
+    var msg = msgInput.value;
+    client.publish(topic, msg);
+};
+
+client.on('connect', () => {
+    client.subscribe('#', { qos: 0 }, (err, granted) => {
+        console.log(err);
+    });
+    client.publish('presence', 'Hello mqtt');
+
+    stateParagraph.innerText = "connected";
+    showMsg("[connect]");
+});
+
+client.on("error", e => {
+    showMsg("error: " + e.message);
+});
+
+client.on("reconnect", () => {
+    stateParagraph.innerText = "reconnecting";
+    showMsg("[reconnect]");
+});
+
+client.on('message', (topic, message) => {
+    showMsg(topic + ": " + message.toString());
+});
+
+function showMsg(msg: string) {
+    //console.log(msg);
+
+    var node = document.createElement("LI");
+    node.appendChild(document.createTextNode(msg));
+
+    msgsList.appendChild(node);
+
+    if (msgsList.childElementCount > 50) {
+        msgsList.removeChild(msgsList.childNodes[0]);
+    }
+}

Source/MQTTnet/Adapter/IMqttChannelAdapter.cs

@@ -10,6 +10,8 @@ namespace MQTTnet.Adapter
     {
         string Endpoint { get; }
 
+        bool IsSecureConnection { get; }
+
         MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
         
         event EventHandler ReadingPacketStarted;

Source/MQTTnet/Adapter/IMqttServerAdapter.cs

@@ -6,7 +6,7 @@ namespace MQTTnet.Adapter
 {
     public interface IMqttServerAdapter : IDisposable
     {
-        event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
+        Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
 
         Task StartAsync(IMqttServerOptions options);
         Task StopAsync();

Source/MQTTnet/Adapter/MqttChannelAdapter.cs

@@ -42,6 +42,8 @@ namespace MQTTnet.Adapter
 
         public string Endpoint => _channel.Endpoint;
 
+        public bool IsSecureConnection => _channel.IsSecureConnection;
+
         public MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
 
         public event EventHandler ReadingPacketStarted;

Source/MQTTnet/Channel/IMqttChannel.cs

@@ -7,6 +7,7 @@ namespace MQTTnet.Channel
     public interface IMqttChannel : IDisposable
     {
         string Endpoint { get; }
+        bool IsSecureConnection { get; }
 
         Task ConnectAsync(CancellationToken cancellationToken);
         Task DisconnectAsync(CancellationToken cancellationToken);

Source/MQTTnet/Client/IMqttClient.cs

@@ -15,13 +15,9 @@ namespace MQTTnet.Client
         IMqttClientOptions Options { get; }
 
         IMqttClientConnectedHandler ConnectedHandler { get; set; }
-        [Obsolete("Use ConnectedHandler instead.")]
-        event EventHandler<MqttClientConnectedEventArgs> Connected;
-
+        
         IMqttClientDisconnectedHandler DisconnectedHandler { get; set; }
-        [Obsolete("Use DisconnectedHandler instead.")]
-        event EventHandler<MqttClientDisconnectedEventArgs> Disconnected;
-
+        
         Task<MqttClientAuthenticateResult> ConnectAsync(IMqttClientOptions options, CancellationToken cancellationToken);
         Task DisconnectAsync(MqttClientDisconnectOptions options, CancellationToken cancellationToken);
 

Source/MQTTnet/Client/MqttClient.cs

@@ -46,15 +46,9 @@ namespace MQTTnet.Client
 
         public IMqttClientConnectedHandler ConnectedHandler { get; set; }
 
-        public event EventHandler<MqttClientConnectedEventArgs> Connected;
-
         public IMqttClientDisconnectedHandler DisconnectedHandler { get; set; }
 
-        public event EventHandler<MqttClientDisconnectedEventArgs> Disconnected;
-
-        public IMqttApplicationMessageHandler ReceivedApplicationMessageHandler { get; set; }
-
-        public event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
+        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler { get; set; }
 
         public bool IsConnected { get; private set; }
 
@@ -106,9 +100,6 @@ namespace MQTTnet.Client
                     await connectedHandler.HandleConnectedAsync(new MqttClientConnectedEventArgs(authenticateResult)).ConfigureAwait(false);
                 }
 
-                // TODO: Remove!
-                Connected?.Invoke(this, new MqttClientConnectedEventArgs(authenticateResult));
-
                 return authenticateResult;
             }
             catch (Exception exception)
@@ -276,8 +267,6 @@ namespace MQTTnet.Client
                 {
                     await disconnectedHandler.HandleDisconnectedAsync(new MqttClientDisconnectedEventArgs(clientWasConnected, exception)).ConfigureAwait(false);
                 }
-
-                Disconnected?.Invoke(this, new MqttClientDisconnectedEventArgs(clientWasConnected, exception));
             }
         }
 
@@ -521,25 +510,27 @@ namespace MQTTnet.Client
                 }
                 else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtLeastOnce)
                 {
-                    await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false);
-
-                    await SendAsync(new MqttPubAckPacket
+                    if (await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false))
                     {
-                        PacketIdentifier = publishPacket.PacketIdentifier,
-                        ReasonCode = MqttPubAckReasonCode.Success
-                    }, cancellationToken).ConfigureAwait(false);
+                        await SendAsync(new MqttPubAckPacket
+                        {
+                            PacketIdentifier = publishPacket.PacketIdentifier,
+                            ReasonCode = MqttPubAckReasonCode.Success
+                        }, cancellationToken).ConfigureAwait(false);
+                    }
                 }
                 else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.ExactlyOnce)
                 {
-                    await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false);
-
-                    var pubRecPacket = new MqttPubRecPacket
+                    if (await HandleReceivedApplicationMessageAsync(publishPacket).ConfigureAwait(false))
                     {
-                        PacketIdentifier = publishPacket.PacketIdentifier,
-                        ReasonCode = MqttPubRecReasonCode.Success
-                    };
+                        var pubRecPacket = new MqttPubRecPacket
+                        {
+                            PacketIdentifier = publishPacket.PacketIdentifier,
+                            ReasonCode = MqttPubRecReasonCode.Success
+                        };
 
-                    await SendAsync(pubRecPacket, cancellationToken).ConfigureAwait(false);
+                        await SendAsync(pubRecPacket, cancellationToken).ConfigureAwait(false);
+                    }                    
                 }
                 else
                 {
@@ -583,20 +574,19 @@ namespace MQTTnet.Client
             return _adapter.PacketFormatterAdapter.DataConverter.CreatePublishResult(pubRecPacket, pubCompPacket);
         }
 
-        private Task HandleReceivedApplicationMessageAsync(MqttPublishPacket publishPacket)
+        private async Task<bool> HandleReceivedApplicationMessageAsync(MqttPublishPacket publishPacket)
         {
             var applicationMessage = _adapter.PacketFormatterAdapter.DataConverter.CreateApplicationMessage(publishPacket);
 
-            ApplicationMessageReceived?.Invoke(this, new MqttApplicationMessageReceivedEventArgs(Options.ClientId, applicationMessage));
-
-            var handler = ReceivedApplicationMessageHandler;
+            var handler = ApplicationMessageReceivedHandler;
             if (handler != null)
             {
-                return handler.HandleApplicationMessageAsync(
-                    new MqttApplicationMessageHandlerContext(Options.ClientId, applicationMessage));
+                var eventArgs = new MqttApplicationMessageReceivedEventArgs(Options.ClientId, applicationMessage);
+                await handler.HandleApplicationMessageReceivedAsync(eventArgs).ConfigureAwait(false);
+                return !eventArgs.ProcessingFailed;
             }
 
-            return Task.FromResult(0);
+            return true;
         }
 
         private static async Task WaitForTaskAsync(Task task, Task sender)

Source/MQTTnet/Client/MqttClientExtensions.cs

@@ -63,35 +63,35 @@ namespace MQTTnet.Client
             return client;
         }
 
-        public static IMqttClient UseReceivedApplicationMessageHandler(this IMqttClient client, Func<MqttApplicationMessageHandlerContext, Task> handler)
+        public static IMqttClient UseApplicationMessageReceivedHandler(this IMqttClient client, Func<MqttApplicationMessageReceivedEventArgs, Task> handler)
         {
             if (handler == null)
             {
-                client.ReceivedApplicationMessageHandler = null;
+                client.ApplicationMessageReceivedHandler = null;
                 return client;
             }
 
-            client.ReceivedApplicationMessageHandler = new MqttApplicationMessageHandlerDelegate(handler);
+            client.ApplicationMessageReceivedHandler = new MqttApplicationMessageReceivedHandlerDelegate(handler);
 
             return client;
         }
 
-        public static IMqttClient UseReceivedApplicationMessageHandler(this IMqttClient client, Action<MqttApplicationMessageHandlerContext> handler)
+        public static IMqttClient UseApplicationMessageReceivedHandler(this IMqttClient client, Action<MqttApplicationMessageReceivedEventArgs> handler)
         {
             if (handler == null)
             {
-                client.ReceivedApplicationMessageHandler = null;
+                client.ApplicationMessageReceivedHandler = null;
                 return client;
             }
 
-            client.ReceivedApplicationMessageHandler = new MqttApplicationMessageHandlerDelegate(handler);
+            client.ApplicationMessageReceivedHandler = new MqttApplicationMessageReceivedHandlerDelegate(handler);
 
             return client;
         }
 
-        public static IMqttClient UseReceivedApplicationMessageHandler(this IMqttClient client, IMqttApplicationMessageHandler handler)
+        public static IMqttClient UseApplicationMessageReceivedHandler(this IMqttClient client, IMqttApplicationMessageReceivedHandler handler)
         {
-            client.ReceivedApplicationMessageHandler = handler;
+            client.ApplicationMessageReceivedHandler = handler;
 
             return client;
         }

Source/MQTTnet/Client/Receiving/IMqttApplicationMessageHandler.cs

@@ -1,9 +0,0 @@
-using System.Threading.Tasks;
-
-namespace MQTTnet.Client.Receiving
-{
-    public interface IMqttApplicationMessageHandler
-    {
-        Task HandleApplicationMessageAsync(MqttApplicationMessageHandlerContext context);
-    }
-}

Source/MQTTnet/Client/Receiving/IMqttApplicationMessageReceivedHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace MQTTnet.Client.Receiving
+{
+    public interface IMqttApplicationMessageReceivedHandler
+    {
+        Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs eventArgs);
+    }
+}

Source/MQTTnet/Client/Receiving/MqttApplicationMessageHandlerContext.cs

@@ -1,15 +0,0 @@
-namespace MQTTnet.Client.Receiving
-{
-    public class MqttApplicationMessageHandlerContext
-    {
-        public MqttApplicationMessageHandlerContext(string senderClientId, MqttApplicationMessage applicationMessage)
-        {
-            SenderClientId = senderClientId;
-            ApplicationMessage = applicationMessage;
-        }
-
-        public string SenderClientId { get; }
-
-        public MqttApplicationMessage ApplicationMessage { get; }
-    }
-}

Source/MQTTnet/Client/Receiving/MqttApplicationMessageHandlerDelegate.cs

@@ -1,31 +0,0 @@
-using System;
-using System.Threading.Tasks;
-
-namespace MQTTnet.Client.Receiving
-{
-    public class MqttApplicationMessageHandlerDelegate : IMqttApplicationMessageHandler
-    {
-        private readonly Func<MqttApplicationMessageHandlerContext, Task> _handler;
-
-        public MqttApplicationMessageHandlerDelegate(Action<MqttApplicationMessageHandlerContext> handler)
-        {
-            if (handler == null) throw new ArgumentNullException(nameof(handler));
-
-            _handler = context =>
-            {
-                handler(context);
-                return Task.FromResult(0);
-            };
-        }
-
-        public MqttApplicationMessageHandlerDelegate(Func<MqttApplicationMessageHandlerContext, Task> handler)
-        {
-            _handler = handler ?? throw new ArgumentNullException(nameof(handler));
-        }
-
-        public Task HandleApplicationMessageAsync(MqttApplicationMessageHandlerContext context)
-        {
-            return _handler(context);
-        }
-    }
-}

Source/MQTTnet/Client/Receiving/MqttApplicationMessageReceivedHandlerDelegate.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Client.Receiving
+{
+    public class MqttApplicationMessageReceivedHandlerDelegate : IMqttApplicationMessageReceivedHandler
+    {
+        private readonly Func<MqttApplicationMessageReceivedEventArgs, Task> _handler;
+
+        public MqttApplicationMessageReceivedHandlerDelegate(Action<MqttApplicationMessageReceivedEventArgs> handler)
+        {
+            if (handler == null) throw new ArgumentNullException(nameof(handler));
+
+            _handler = context =>
+            {
+                handler(context);
+                return Task.FromResult(0);
+            };
+        }
+
+        public MqttApplicationMessageReceivedHandlerDelegate(Func<MqttApplicationMessageReceivedEventArgs, Task> handler)
+        {
+            _handler = handler ?? throw new ArgumentNullException(nameof(handler));
+        }
+
+        public Task HandleApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs context)
+        {
+            return _handler(context);
+        }
+    }
+}

Source/MQTTnet/IApplicationMessageReceiver.cs

@@ -1,13 +1,9 @@
-using System;
-using MQTTnet.Client.Receiving;
+using MQTTnet.Client.Receiving;
 
 namespace MQTTnet
 {
     public interface IApplicationMessageReceiver
     {
-        IMqttApplicationMessageHandler ReceivedApplicationMessageHandler { get; set; }
-
-        [Obsolete("Use _ReceivedApplicationMessageHandler_ instead.")]
-        event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
+        IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler { get; set; }
     }
 }

Source/MQTTnet/IMqttFactory.cs

@@ -0,0 +1,11 @@
+using MQTTnet.Client;
+using MQTTnet.Diagnostics;
+using MQTTnet.Server;
+
+namespace MQTTnet
+{
+    public interface IMqttFactory : IMqttClientFactory, IMqttServerFactory
+    {
+        IMqttNetLogger DefaultLogger { get; }
+    }
+}

Source/MQTTnet/Implementations/MqttClientAdapterFactory.cs

@@ -1,6 +1,5 @@
 using System;
 using MQTTnet.Adapter;
-using MQTTnet.Client;
 using MQTTnet.Client.Options;
 using MQTTnet.Diagnostics;
 using MQTTnet.Formatter;

Source/MQTTnet/Implementations/MqttTcpChannel.Uwp.cs

@@ -36,6 +36,8 @@ namespace MQTTnet.Implementations
             _bufferSize = serverOptions.DefaultEndpointOptions.BufferSize;
 
             CreateStreams();
+
+            IsSecureConnection = socket.Information.ProtectionLevel >= SocketProtectionLevel.Tls12;
         }
 
         public static Func<MqttClientTcpOptions, IEnumerable<ChainValidationResult>> CustomIgnorableServerCertificateErrorsResolver { get; set; }
@@ -53,6 +55,8 @@ namespace MQTTnet.Implementations
             }
         }
 
+        public bool IsSecureConnection { get; }
+
         public async Task ConnectAsync(CancellationToken cancellationToken)
         {
             if (_socket == null)

Source/MQTTnet/Implementations/MqttTcpChannel.cs

@@ -27,6 +27,8 @@ namespace MQTTnet.Implementations
         {
             _clientOptions = clientOptions ?? throw new ArgumentNullException(nameof(clientOptions));
             _options = (MqttClientTcpOptions)clientOptions.ChannelOptions;
+
+            IsSecureConnection = clientOptions.ChannelOptions?.TlsOptions?.UseTls == true;
         }
 
         /// <summary>
@@ -37,6 +39,8 @@ namespace MQTTnet.Implementations
         {
             _socket = socket ?? throw new ArgumentNullException(nameof(socket));
 
+            IsSecureConnection = sslStream != null;
+
             CreateStream(sslStream);
         }
 
@@ -45,6 +49,8 @@ namespace MQTTnet.Implementations
 
         public string Endpoint => _socket?.RemoteEndPoint?.ToString();
 
+        public bool IsSecureConnection { get; }
+
         public async Task ConnectAsync(CancellationToken cancellationToken)
         {
             if (_socket == null)

Source/MQTTnet/Implementations/MqttTcpServerAdapter.Uwp.cs

@@ -23,7 +23,7 @@ namespace MQTTnet.Implementations
             _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
         }
 
-        public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
+        public Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
 
         public async Task StartAsync(IMqttServerOptions options)
         {
@@ -73,7 +73,7 @@ namespace MQTTnet.Implementations
             try
             {
                 var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(args.Socket, _options), new MqttPacketFormatterAdapter(), _logger);
-                ClientAccepted?.Invoke(this, new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
+                ClientAcceptedHandler?.Invoke(new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
             }
             catch (Exception exception)
             {

Source/MQTTnet/Implementations/MqttTcpServerAdapter.cs

@@ -26,7 +26,7 @@ namespace MQTTnet.Implementations
             _logger = logger.CreateChildLogger(nameof(MqttTcpServerAdapter));
         }
 
-        public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
+        public Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler { get; set; }
 
         public Task StartAsync(IMqttServerOptions options)
         {
@@ -87,9 +87,11 @@ namespace MQTTnet.Implementations
                     options,
                     tlsCertificate,
                     _cancellationTokenSource.Token,
-                    _logger);
+                    _logger)
+                {
+                    ClientAcceptedHandler = OnClientAccepted
+                };
 
-                listenerV4.ClientAccepted += OnClientAccepted;
                 listenerV4.Start();
                 _listeners.Add(listenerV4);
             }
@@ -101,17 +103,19 @@ namespace MQTTnet.Implementations
                     options,
                     tlsCertificate,
                     _cancellationTokenSource.Token,
-                    _logger);
+                    _logger)
+                {
+                    ClientAcceptedHandler = OnClientAccepted
+                };
 
-                listenerV6.ClientAccepted += OnClientAccepted;
                 listenerV6.Start();
                 _listeners.Add(listenerV6);
             }
         }
 
-        private void OnClientAccepted(object sender, MqttServerAdapterClientAcceptedEventArgs e)
+        private void OnClientAccepted(MqttServerAdapterClientAcceptedEventArgs eventArgs)
         {
-            ClientAccepted?.Invoke(this, e);
+            ClientAcceptedHandler?.Invoke(eventArgs);
         }
     }
 }

Source/MQTTnet/Implementations/MqttTcpServerListener.cs

@@ -42,7 +42,7 @@ namespace MQTTnet.Implementations
             }
         }
 
-        public event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
+        public Action<MqttServerAdapterClientAcceptedEventArgs> ClientAcceptedHandler;
 
         public void Start()
         {
@@ -88,7 +88,7 @@ namespace MQTTnet.Implementations
                         _addressFamily == AddressFamily.InterNetwork ? "ipv4" : "ipv6");
 
                     var clientAdapter = new MqttChannelAdapter(new MqttTcpChannel(clientSocket, sslStream), new MqttPacketFormatterAdapter(), _logger);
-                    ClientAccepted?.Invoke(this, new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
+                    ClientAcceptedHandler?.Invoke(new MqttServerAdapterClientAcceptedEventArgs(clientAdapter));
                 }
                 catch (ObjectDisposedException)
                 {

Source/MQTTnet/Implementations/MqttWebSocketChannel.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Globalization;
 using System.Net;
 using System.Net.WebSockets;
 using System.Security.Cryptography.X509Certificates;
@@ -21,14 +22,18 @@ namespace MQTTnet.Implementations
             _options = options ?? throw new ArgumentNullException(nameof(options));
         }
 
-        public MqttWebSocketChannel(WebSocket webSocket, string endpoint)
+        public MqttWebSocketChannel(WebSocket webSocket, string endpoint, bool isSecureConnection)
         {
             _webSocket = webSocket ?? throw new ArgumentNullException(nameof(webSocket));
+
             Endpoint = endpoint;
+            IsSecureConnection = isSecureConnection;
         }
 
         public string Endpoint { get; }
 
+        public bool IsSecureConnection { get; private set; }
+
         public async Task ConnectAsync(CancellationToken cancellationToken)
         {
             var uri = _options.Uri;
@@ -83,6 +88,8 @@ namespace MQTTnet.Implementations
 
             await clientWebSocket.ConnectAsync(new Uri(uri), cancellationToken).ConfigureAwait(false);
             _webSocket = clientWebSocket;
+
+            IsSecureConnection = uri.StartsWith("wss://", StringComparison.OrdinalIgnoreCase);
         }
 
         public async Task DisconnectAsync(CancellationToken cancellationToken)

Source/MQTTnet/Internal/TestMqttChannel.cs

@@ -16,6 +16,8 @@ namespace MQTTnet.Internal
 
         public string Endpoint { get; } = "<Test channel>";
 
+        public bool IsSecureConnection { get; } = false;
+
         public Task ConnectAsync(CancellationToken cancellationToken)
         {
             return Task.FromResult(0);

Source/MQTTnet/MqttApplicationMessageReceivedEventArgs.cs

@@ -13,5 +13,7 @@ namespace MQTTnet
         public string ClientId { get; }
 
         public MqttApplicationMessage ApplicationMessage { get; }
+
+        public bool ProcessingFailed { get; set; }
     }
 }

Source/MQTTnet/MqttFactory.cs

@@ -8,11 +8,22 @@ using MQTTnet.Server;
 
 namespace MQTTnet
 {
-    public class MqttFactory : IMqttClientFactory, IMqttServerFactory
+    public class MqttFactory : IMqttFactory
     {
+        public MqttFactory() : this(new MqttNetLogger())
+        {
+        }
+
+        public MqttFactory(IMqttNetLogger logger)
+        {
+            DefaultLogger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public IMqttNetLogger DefaultLogger { get; }
+
         public IMqttClient CreateMqttClient()
         {
-            return CreateMqttClient(new MqttNetLogger());
+            return CreateMqttClient(DefaultLogger);
         }
 
         public IMqttClient CreateMqttClient(IMqttNetLogger logger)
@@ -26,7 +37,7 @@ namespace MQTTnet
         {
             if (adapterFactory == null) throw new ArgumentNullException(nameof(adapterFactory));
 
-            return new MqttClient(adapterFactory, new MqttNetLogger());
+            return new MqttClient(adapterFactory, DefaultLogger);
         }
 
         public IMqttClient CreateMqttClient(IMqttNetLogger logger, IMqttClientAdapterFactory adapterFactory)
@@ -39,8 +50,7 @@ namespace MQTTnet
 
         public IMqttServer CreateMqttServer()
         {
-            var logger = new MqttNetLogger();
-            return CreateMqttServer(logger);
+            return CreateMqttServer(DefaultLogger);
         }
 
         public IMqttServer CreateMqttServer(IMqttNetLogger logger)
@@ -57,5 +67,12 @@ namespace MQTTnet
 
             return new MqttServer(adapters, logger.CreateChildLogger());
         }
+
+        public IMqttServer CreateMqttServer(IEnumerable<IMqttServerAdapter> adapters)
+        {
+            if (adapters == null) throw new ArgumentNullException(nameof(adapters));
+            
+            return new MqttServer(adapters, DefaultLogger.CreateChildLogger());
+        }
     }
 }

Source/MQTTnet/Packets/MqttConnectPacket.cs

@@ -27,7 +27,13 @@
 
         public override string ToString()
         {
-            return string.Concat("Connect: [ProtocolLevel=", ProtocolLevel, "] [ClientId=", ClientId, "] [Username=", Username, "] [Password=", Password, "] [KeepAlivePeriod=", KeepAlivePeriod, "] [CleanSession=", CleanSession, "]");
+            var password = Password;
+            if (!string.IsNullOrEmpty(password))
+            {
+                password = "****";
+            }
+
+            return string.Concat("Connect: [ProtocolLevel=", ProtocolLevel, "] [ClientId=", ClientId, "] [Username=", Username, "] [Password=", password, "] [KeepAlivePeriod=", KeepAlivePeriod, "] [CleanSession=", CleanSession, "]");
         }
     }
 }

Source/MQTTnet/Server/IMqttServer.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using MQTTnet.Server.Status;
 
@@ -7,13 +6,13 @@ namespace MQTTnet.Server
 {
     public interface IMqttServer : IApplicationMessageReceiver, IApplicationMessagePublisher
     {
-        event EventHandler Started;
-        event EventHandler Stopped;
+        IMqttServerStartedHandler StartedHandler { get; set; }
+        IMqttServerStoppedHandler StoppedHandler { get; set; }
 
-        event EventHandler<MqttClientConnectedEventArgs> ClientConnected;
-        event EventHandler<MqttClientDisconnectedEventArgs> ClientDisconnected;
-        event EventHandler<MqttClientSubscribedTopicEventArgs> ClientSubscribedTopic;
-        event EventHandler<MqttClientUnsubscribedTopicEventArgs> ClientUnsubscribedTopic;
+        IMqttServerClientConnectedHandler ClientConnectedHandler { get; set; }
+        IMqttServerClientDisconnectedHandler ClientDisconnectedHandler { get; set; }
+        IMqttServerClientSubscribedTopicHandler ClientSubscribedTopicHandler { get; set; }
+        IMqttServerClientUnsubscribedTopicHandler ClientUnsubscribedTopicHandler { get; set; }
         
         IMqttServerOptions Options { get; }
 

Source/MQTTnet/Server/IMqttServerClientConnectedHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace MQTTnet.Server
+{
+    public interface IMqttServerClientConnectedHandler
+    {
+        Task HandleClientConnectedAsync(MqttServerClientConnectedEventArgs eventArgs);
+    }
+}

Source/MQTTnet/Server/IMqttServerClientDisconnectedHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace MQTTnet.Server
+{
+    public interface IMqttServerClientDisconnectedHandler
+    {
+        Task HandleClientDisconnectedAsync(MqttServerClientDisconnectedEventArgs eventArgs);
+    }
+}

Source/MQTTnet/Server/IMqttServerClientSubscribedTopicHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace MQTTnet.Server
+{
+    public interface IMqttServerClientSubscribedTopicHandler
+    {
+        Task HandleClientSubscribedTopicAsync(MqttServerClientSubscribedTopicEventArgs eventArgs);
+    }
+}

Source/MQTTnet/Server/IMqttServerClientUnsubscribedTopicHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace MQTTnet.Server
+{
+    public interface IMqttServerClientUnsubscribedTopicHandler
+    {
+        Task HandleClientUnsubscribedTopicAsync(MqttServerClientUnsubscribedTopicEventArgs eventArgs);
+    }
+}

Source/MQTTnet/Server/IMqttServerFactory.cs

@@ -10,6 +10,8 @@ namespace MQTTnet.Server
 
         IMqttServer CreateMqttServer(IMqttNetLogger logger);
 
+        IMqttServer CreateMqttServer(IEnumerable<IMqttServerAdapter> adapters);
+
         IMqttServer CreateMqttServer(IEnumerable<IMqttServerAdapter> adapters, IMqttNetLogger logger);
     }
 }

Source/MQTTnet/Server/IMqttServerStartedHandler.cs

@@ -0,0 +1,10 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Server
+{
+    public interface IMqttServerStartedHandler
+    {
+        Task HandleServerStartedAsync(EventArgs eventArgs);
+    }
+}

Source/MQTTnet/Server/IMqttServerStoppedHandler.cs

@@ -0,0 +1,10 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Server
+{
+    public interface IMqttServerStoppedHandler
+    {
+        Task HandleServerStoppedAsync(EventArgs eventArgs);
+    }
+}

Source/MQTTnet/Server/MqttClientConnection.cs

@@ -14,62 +14,6 @@ using MQTTnet.Server.Status;
 
 namespace MQTTnet.Server
 {
-    public class MqttClientSession
-    {
-        private readonly DateTime _createdTimestamp = DateTime.UtcNow;
-
-        public MqttClientSession(string clientId, MqttServerEventDispatcher eventDispatcher, IMqttServerOptions serverOptions)
-        {
-            ClientId = clientId ?? throw new ArgumentNullException(nameof(clientId));
-
-            SubscriptionsManager = new MqttClientSubscriptionsManager(clientId, eventDispatcher, serverOptions);
-            ApplicationMessagesQueue = new MqttClientSessionApplicationMessagesQueue(serverOptions);
-        }
-
-        public string ClientId { get; }
-
-        public bool IsCleanSession { get; set; } = true;
-
-        public MqttApplicationMessage WillMessage { get; set; }
-
-        public MqttClientSubscriptionsManager SubscriptionsManager { get; }
-
-        public MqttClientSessionApplicationMessagesQueue ApplicationMessagesQueue { get; }
-
-        public void EnqueueApplicationMessage(MqttApplicationMessage applicationMessage, string senderClientId, bool isRetainedApplicationMessage)
-        {
-            var checkSubscriptionsResult = SubscriptionsManager.CheckSubscriptions(applicationMessage.Topic, applicationMessage.QualityOfServiceLevel);
-            if (!checkSubscriptionsResult.IsSubscribed)
-            {
-                return;
-            }
-
-            ApplicationMessagesQueue.Enqueue(applicationMessage, senderClientId, checkSubscriptionsResult.QualityOfServiceLevel, isRetainedApplicationMessage);
-        }
-
-        public async Task SubscribeAsync(ICollection<TopicFilter> topicFilters, MqttRetainedMessagesManager retainedMessagesManager)
-        {
-            await SubscriptionsManager.SubscribeAsync(topicFilters).ConfigureAwait(false);
-            var matchingRetainedMessages = await retainedMessagesManager.GetSubscribedMessagesAsync(topicFilters).ConfigureAwait(false);
-            foreach (var matchingRetainedMessage in matchingRetainedMessages)
-            {
-                EnqueueApplicationMessage(matchingRetainedMessage, null, true);
-            }
-        }
-
-        public Task UnsubscribeAsync(IEnumerable<string> topicFilters)
-        {
-            return SubscriptionsManager.UnsubscribeAsync(topicFilters);
-        }
-
-        public void FillStatus(MqttSessionStatus status)
-        {
-            status.ClientId = ClientId;
-            status.CreatedTimestamp = _createdTimestamp;
-            status.PendingApplicationMessagesCount = ApplicationMessagesQueue.Count;
-        }
-    }
-
     public class MqttClientConnection : IMqttClientSession, IDisposable
     {
         private readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
@@ -425,7 +369,7 @@ namespace MQTTnet.Server
             ////    }
             ////});
 
-            await Task.FromResult(0);
+            //await Task.FromResult(0);
         }
 
         private async Task SendPendingPacketsAsync()

Source/MQTTnet/Server/MqttClientSession.cs

@@ -0,0 +1,63 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using MQTTnet.Server.Status;
+
+namespace MQTTnet.Server
+{
+    public class MqttClientSession
+    {
+        private readonly DateTime _createdTimestamp = DateTime.UtcNow;
+
+        public MqttClientSession(string clientId, MqttServerEventDispatcher eventDispatcher, IMqttServerOptions serverOptions)
+        {
+            ClientId = clientId ?? throw new ArgumentNullException(nameof(clientId));
+
+            SubscriptionsManager = new MqttClientSubscriptionsManager(clientId, eventDispatcher, serverOptions);
+            ApplicationMessagesQueue = new MqttClientSessionApplicationMessagesQueue(serverOptions);
+        }
+
+        public string ClientId { get; }
+
+        public bool IsCleanSession { get; set; } = true;
+
+        public MqttApplicationMessage WillMessage { get; set; }
+
+        public MqttClientSubscriptionsManager SubscriptionsManager { get; }
+
+        public MqttClientSessionApplicationMessagesQueue ApplicationMessagesQueue { get; }
+
+        public void EnqueueApplicationMessage(MqttApplicationMessage applicationMessage, string senderClientId, bool isRetainedApplicationMessage)
+        {
+            var checkSubscriptionsResult = SubscriptionsManager.CheckSubscriptions(applicationMessage.Topic, applicationMessage.QualityOfServiceLevel);
+            if (!checkSubscriptionsResult.IsSubscribed)
+            {
+                return;
+            }
+
+            ApplicationMessagesQueue.Enqueue(applicationMessage, senderClientId, checkSubscriptionsResult.QualityOfServiceLevel, isRetainedApplicationMessage);
+        }
+
+        public async Task SubscribeAsync(ICollection<TopicFilter> topicFilters, MqttRetainedMessagesManager retainedMessagesManager)
+        {
+            await SubscriptionsManager.SubscribeAsync(topicFilters).ConfigureAwait(false);
+            var matchingRetainedMessages = await retainedMessagesManager.GetSubscribedMessagesAsync(topicFilters).ConfigureAwait(false);
+            foreach (var matchingRetainedMessage in matchingRetainedMessages)
+            {
+                EnqueueApplicationMessage(matchingRetainedMessage, null, true);
+            }
+        }
+
+        public Task UnsubscribeAsync(IEnumerable<string> topicFilters)
+        {
+            return SubscriptionsManager.UnsubscribeAsync(topicFilters);
+        }
+
+        public void FillStatus(MqttSessionStatus status)
+        {
+            status.ClientId = ClientId;
+            status.CreatedTimestamp = _createdTimestamp;
+            status.PendingApplicationMessagesCount = ApplicationMessagesQueue.Count;
+        }
+    }
+}

Source/MQTTnet/Server/MqttClientSessionsManager.cs

@@ -15,6 +15,7 @@ namespace MQTTnet.Server
     {
         private readonly BlockingCollection<MqttEnqueuedApplicationMessage> _messageQueue = new BlockingCollection<MqttEnqueuedApplicationMessage>();
 
+        private readonly SemaphoreSlim _createConnectionGate = new SemaphoreSlim(1, 1);
         private readonly ConcurrentDictionary<string, MqttClientConnection> _connections = new ConcurrentDictionary<string, MqttClientConnection>();
         private readonly ConcurrentDictionary<string, MqttClientSession> _sessions = new ConcurrentDictionary<string, MqttClientSession>();
         
@@ -49,8 +50,6 @@ namespace MQTTnet.Server
 
         public async Task StopAsync()
         {
-            //using (await _sessionsLock.WaitAsync(CancellationToken.None).ConfigureAwait(false))
-
             foreach (var connection in _connections.Values)
             {
                 await connection.StopAsync().ConfigureAwait(false);
@@ -133,7 +132,7 @@ namespace MQTTnet.Server
         {
             if (_connections.TryGetValue(clientId, out var connection))
             {
-                await connection.StopAsync();
+                await connection.StopAsync().ConfigureAwait(false);
             }
 
             if (_sessions.TryRemove(clientId, out var session))
@@ -196,7 +195,7 @@ namespace MQTTnet.Server
                     applicationMessage = interceptorContext.ApplicationMessage;
                 }
 
-                _eventDispatcher.OnApplicationMessageReceived(sender?.ClientId, applicationMessage);
+                await _eventDispatcher.HandleApplicationMessageReceivedAsync(sender?.ClientId, applicationMessage).ConfigureAwait(false);
 
                 if (applicationMessage.Retain)
                 {
@@ -258,7 +257,7 @@ namespace MQTTnet.Server
 
                 var connection = await CreateConnectionAsync(channelAdapter, connectPacket).ConfigureAwait(false);
 
-                _eventDispatcher.OnClientConnected(clientId);
+                await _eventDispatcher.HandleClientConnectedAsync(clientId).ConfigureAwait(false);
                 
                 disconnectType = await connection.RunAsync().ConfigureAwait(false);
             }
@@ -288,7 +287,7 @@ namespace MQTTnet.Server
 
                 await TryCleanupChannelAsync(channelAdapter).ConfigureAwait(false);
 
-                _eventDispatcher.OnClientDisconnected(clientId, disconnectType);
+                await _eventDispatcher.HandleClientDisconnectedAsync(clientId, disconnectType).ConfigureAwait(false);
             }
         }
 
@@ -299,7 +298,8 @@ namespace MQTTnet.Server
                 connectPacket.Username,
                 connectPacket.Password,
                 connectPacket.WillMessage,
-                clientAdapter.Endpoint);
+                clientAdapter.Endpoint,
+                clientAdapter.IsSecureConnection);
 
             var connectionValidator = _options.ConnectionValidator;
 
@@ -313,8 +313,6 @@ namespace MQTTnet.Server
             return context;
         }
 
-        private readonly SemaphoreSlim _createConnectionGate = new SemaphoreSlim(1, 1);
-
         private async Task<MqttClientConnection> CreateConnectionAsync(IMqttChannelAdapter channelAdapter, MqttConnectPacket connectPacket)
         {
             await _createConnectionGate.WaitAsync(_cancellationToken).ConfigureAwait(false);

Source/MQTTnet/Server/MqttClientSubscriptionsManager.cs

@@ -61,7 +61,7 @@ namespace MQTTnet.Server
                         _subscriptions[topicFilter.Topic] = topicFilter.QualityOfServiceLevel;
                     }
 
-                    _eventDispatcher.OnClientSubscribedTopic(_clientId, topicFilter);
+                    await _eventDispatcher.HandleClientSubscribedTopicAsync(_clientId, topicFilter).ConfigureAwait(false);
                 }
             }
 
@@ -85,12 +85,12 @@ namespace MQTTnet.Server
                         _subscriptions[topicFilter.Topic] = topicFilter.QualityOfServiceLevel;
                     }
 
-                    _eventDispatcher.OnClientSubscribedTopic(_clientId, topicFilter);
+                    await _eventDispatcher.HandleClientSubscribedTopicAsync(_clientId, topicFilter).ConfigureAwait(false);
                 }
             }
         }
 
-        public Task<MqttUnsubAckPacket> UnsubscribeAsync(MqttUnsubscribePacket unsubscribePacket)
+        public async Task<MqttUnsubAckPacket> UnsubscribeAsync(MqttUnsubscribePacket unsubscribePacket)
         {
             if (unsubscribePacket == null) throw new ArgumentNullException(nameof(unsubscribePacket));
 
@@ -111,12 +111,15 @@ namespace MQTTnet.Server
                     {
                         unsubAckPacket.ReasonCodes.Add(MqttUnsubscribeReasonCode.NoSubscriptionExisted);
                     }
-
-                    _eventDispatcher.OnClientUnsubscribedTopic(_clientId, topicFilter);
                 }
             }
 
-            return Task.FromResult(unsubAckPacket);
+            foreach (var topicFilter in unsubscribePacket.TopicFilters)
+            {
+                await _eventDispatcher.HandleClientUnsubscribedTopicAsync(_clientId, topicFilter).ConfigureAwait(false);
+            }
+            
+            return unsubAckPacket;
         }
 
         public Task UnsubscribeAsync(IEnumerable<string> topicFilters)

Source/MQTTnet/Server/MqttConnectionValidatorContext.cs

@@ -4,13 +4,14 @@ namespace MQTTnet.Server
 {
     public class MqttConnectionValidatorContext
     {
-        public MqttConnectionValidatorContext(string clientId, string username, string password, MqttApplicationMessage willMessage, string endpoint)
+        public MqttConnectionValidatorContext(string clientId, string username, string password, MqttApplicationMessage willMessage, string endpoint, bool isSecureConnection)
         {
             ClientId = clientId;
             Username = username;
             Password = password;
             WillMessage = willMessage;
             Endpoint = endpoint;
+            IsSecureConnection = isSecureConnection;
         }
 
         public string ClientId { get; }
@@ -23,6 +24,8 @@ namespace MQTTnet.Server
 
         public string Endpoint { get; }
 
+        public bool IsSecureConnection { get; }
+
         public MqttConnectReturnCode ReturnCode { get; set; } = MqttConnectReturnCode.ConnectionAccepted;
     }
 }

Source/MQTTnet/Server/MqttServer.cs

@@ -28,35 +28,41 @@ namespace MQTTnet.Server
 
             if (logger == null) throw new ArgumentNullException(nameof(logger));
             _logger = logger.CreateChildLogger(nameof(MqttServer));
-
-            _eventDispatcher.ClientConnected += (s, e) => ClientConnected?.Invoke(s, e);
-            _eventDispatcher.ClientDisconnected += (s, e) => ClientDisconnected?.Invoke(s, e);
-            _eventDispatcher.ClientSubscribedTopic += (s, e) => ClientSubscribedTopic?.Invoke(s, e);
-            _eventDispatcher.ClientUnsubscribedTopic += (s, e) => ClientUnsubscribedTopic?.Invoke(s, e);
-            _eventDispatcher.ApplicationMessageReceived += async (s, e) =>
-            {
-                // TODO: Migrate EventDispatcher to proper handlers and no events anymore.
-                ApplicationMessageReceived?.Invoke(s, e);
-
-                var handler = ReceivedApplicationMessageHandler;
-                if (handler != null)
-                {
-                    await handler.HandleApplicationMessageAsync(
-                        new MqttApplicationMessageHandlerContext(e.ClientId, e.ApplicationMessage)).ConfigureAwait(false);
-                }
-            };
         }
 
-        public event EventHandler Started;
-        public event EventHandler Stopped;
+        public IMqttServerStartedHandler StartedHandler { get; set; }
 
-        public event EventHandler<MqttClientConnectedEventArgs> ClientConnected;
-        public event EventHandler<MqttClientDisconnectedEventArgs> ClientDisconnected;
-        public event EventHandler<MqttClientSubscribedTopicEventArgs> ClientSubscribedTopic;
-        public event EventHandler<MqttClientUnsubscribedTopicEventArgs> ClientUnsubscribedTopic;
+        public IMqttServerStoppedHandler StoppedHandler { get; set; }
 
-        public IMqttApplicationMessageHandler ReceivedApplicationMessageHandler { get; set; }
-        public event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
+        public IMqttServerClientConnectedHandler ClientConnectedHandler
+        {
+            get => _eventDispatcher.ClientConnectedHandler;
+            set => _eventDispatcher.ClientConnectedHandler = value;
+        }
+
+        public IMqttServerClientDisconnectedHandler ClientDisconnectedHandler
+        {
+            get => _eventDispatcher.ClientDisconnectedHandler;
+            set => _eventDispatcher.ClientDisconnectedHandler = value;
+        }
+        
+        public IMqttServerClientSubscribedTopicHandler ClientSubscribedTopicHandler
+        {
+            get => _eventDispatcher.ClientSubscribedTopicHandler;
+            set => _eventDispatcher.ClientSubscribedTopicHandler = value;
+        }
+
+        public IMqttServerClientUnsubscribedTopicHandler ClientUnsubscribedTopicHandler
+        {
+            get => _eventDispatcher.ClientUnsubscribedTopicHandler;
+            set => _eventDispatcher.ClientUnsubscribedTopicHandler = value;
+        }
+        
+        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler
+        {
+            get => _eventDispatcher.ApplicationMessageReceivedHandler;
+            set => _eventDispatcher.ApplicationMessageReceivedHandler = value;
+        }
 
         public IMqttServerOptions Options { get; private set; }
 
@@ -118,12 +124,17 @@ namespace MQTTnet.Server
 
             foreach (var adapter in _adapters)
             {
-                adapter.ClientAccepted += OnClientAccepted;
+                adapter.ClientAcceptedHandler = OnClientAccepted;
                 await adapter.StartAsync(Options).ConfigureAwait(false);
             }
 
             _logger.Info("Started.");
-            Started?.Invoke(this, EventArgs.Empty);
+
+            var startedHandler = StartedHandler;
+            if (startedHandler != null)
+            {
+                await startedHandler.HandleServerStartedAsync(EventArgs.Empty).ConfigureAwait(false);
+            }
         }
 
         public async Task StopAsync()
@@ -141,12 +152,11 @@ namespace MQTTnet.Server
 
                 foreach (var adapter in _adapters)
                 {
-                    adapter.ClientAccepted -= OnClientAccepted;
+                    adapter.ClientAcceptedHandler = null;
                     await adapter.StopAsync().ConfigureAwait(false);
                 }
 
                 _logger.Info("Stopped.");
-                Stopped?.Invoke(this, EventArgs.Empty);
             }
             finally
             {
@@ -158,6 +168,12 @@ namespace MQTTnet.Server
                 _clientSessionsManager?.Dispose();
                 _clientSessionsManager = null;
             }
+
+            var stoppedHandler = StoppedHandler;
+            if (stoppedHandler != null)
+            {
+                await stoppedHandler.HandleServerStoppedAsync(EventArgs.Empty).ConfigureAwait(false);
+            }
         }
 
         public Task ClearRetainedMessagesAsync()
@@ -165,7 +181,7 @@ namespace MQTTnet.Server
             return _retainedMessagesManager?.ClearMessagesAsync();
         }
 
-        private void OnClientAccepted(object sender, MqttServerAdapterClientAcceptedEventArgs eventArgs)
+        private void OnClientAccepted(MqttServerAdapterClientAcceptedEventArgs eventArgs)
         {
             eventArgs.SessionTask = _clientSessionsManager.HandleConnectionAsync(eventArgs.Client);
         }

Source/MQTTnet/Server/MqttServerClientConnectedEventArgs.cs

@@ -2,9 +2,9 @@
 
 namespace MQTTnet.Server
 {
-    public class MqttClientConnectedEventArgs : EventArgs
+    public class MqttServerClientConnectedEventArgs : EventArgs
     {
-        public MqttClientConnectedEventArgs(string clientId)
+        public MqttServerClientConnectedEventArgs(string clientId)
         {
             ClientId = clientId ?? throw new ArgumentNullException(nameof(clientId));
         }

Source/MQTTnet/Server/MqttServerClientConnectedHandlerDelegate.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Server
+{
+    public class MqttServerClientConnectedHandlerDelegate : IMqttServerClientConnectedHandler
+    {
+        private readonly Func<MqttServerClientConnectedEventArgs, Task> _handler;
+
+        public MqttServerClientConnectedHandlerDelegate(Action<MqttServerClientConnectedEventArgs> handler)
+        {
+            if (handler == null) throw new ArgumentNullException(nameof(handler));
+
+            _handler = eventArgs =>
+            {
+                handler(eventArgs);
+                return Task.FromResult(0);
+            };
+        }
+
+        public MqttServerClientConnectedHandlerDelegate(Func<MqttServerClientConnectedEventArgs, Task> handler)
+        {
+            _handler = handler ?? throw new ArgumentNullException(nameof(handler));
+        }
+
+        public Task HandleClientConnectedAsync(MqttServerClientConnectedEventArgs eventArgs)
+        {
+            return _handler(eventArgs);
+        }
+    }
+}

Source/MQTTnet/Server/MqttServerClientDisconnectedEventArgs.cs

@@ -2,9 +2,9 @@
 
 namespace MQTTnet.Server
 {
-    public class MqttClientDisconnectedEventArgs : EventArgs
+    public class MqttServerClientDisconnectedEventArgs : EventArgs
     {
-        public MqttClientDisconnectedEventArgs(string clientId, MqttClientDisconnectType disconnectType)
+        public MqttServerClientDisconnectedEventArgs(string clientId, MqttClientDisconnectType disconnectType)
         {
             ClientId = clientId ?? throw new ArgumentNullException(nameof(clientId));
             DisconnectType = disconnectType;

Source/MQTTnet/Server/MqttServerClientDisconnectedHandlerDelegate.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Server
+{
+    public class MqttServerClientDisconnectedHandlerDelegate : IMqttServerClientDisconnectedHandler
+    {
+        private readonly Func<MqttServerClientDisconnectedEventArgs, Task> _handler;
+
+        public MqttServerClientDisconnectedHandlerDelegate(Action<MqttServerClientDisconnectedEventArgs> handler)
+        {
+            if (handler == null) throw new ArgumentNullException(nameof(handler));
+
+            _handler = eventArgs =>
+            {
+                handler(eventArgs);
+                return Task.FromResult(0);
+            };
+        }
+
+        public MqttServerClientDisconnectedHandlerDelegate(Func<MqttServerClientDisconnectedEventArgs, Task> handler)
+        {
+            _handler = handler ?? throw new ArgumentNullException(nameof(handler));
+        }
+
+        public Task HandleClientDisconnectedAsync(MqttServerClientDisconnectedEventArgs eventArgs)
+        {
+            return _handler(eventArgs);
+        }
+    }
+}

Source/MQTTnet/Server/MqttServerClientSubscribedTopicEventArgs.cs

@@ -2,9 +2,9 @@
 
 namespace MQTTnet.Server
 {
-    public class MqttClientSubscribedTopicEventArgs : EventArgs
+    public class MqttServerClientSubscribedTopicEventArgs : EventArgs
     {
-        public MqttClientSubscribedTopicEventArgs(string clientId, TopicFilter topicFilter)
+        public MqttServerClientSubscribedTopicEventArgs(string clientId, TopicFilter topicFilter)
         {
             ClientId = clientId ?? throw new ArgumentNullException(nameof(clientId));
             TopicFilter = topicFilter ?? throw new ArgumentNullException(nameof(topicFilter));

Source/MQTTnet/Server/MqttServerClientSubscribedTopicHandlerDelegate.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Server
+{
+    public class MqttServerClientSubscribedHandlerDelegate : IMqttServerClientSubscribedTopicHandler
+    {
+        private readonly Func<MqttServerClientSubscribedTopicEventArgs, Task> _handler;
+
+        public MqttServerClientSubscribedHandlerDelegate(Action<MqttServerClientSubscribedTopicEventArgs> handler)
+        {
+            if (handler == null) throw new ArgumentNullException(nameof(handler));
+
+            _handler = eventArgs =>
+            {
+                handler(eventArgs);
+                return Task.FromResult(0);
+            };
+        }
+
+        public MqttServerClientSubscribedHandlerDelegate(Func<MqttServerClientSubscribedTopicEventArgs, Task> handler)
+        {
+            _handler = handler ?? throw new ArgumentNullException(nameof(handler));
+        }
+
+        public Task HandleClientSubscribedTopicAsync(MqttServerClientSubscribedTopicEventArgs eventArgs)
+        {
+            return _handler(eventArgs);
+        }
+    }
+}

Source/MQTTnet/Server/MqttServerClientUnsubscribedTopicEventArgs.cs

@@ -2,9 +2,9 @@
 
 namespace MQTTnet.Server
 {
-    public class MqttClientUnsubscribedTopicEventArgs : EventArgs
+    public class MqttServerClientUnsubscribedTopicEventArgs : EventArgs
     {
-        public MqttClientUnsubscribedTopicEventArgs(string clientId, string topicFilter)
+        public MqttServerClientUnsubscribedTopicEventArgs(string clientId, string topicFilter)
         {
             ClientId = clientId ?? throw new ArgumentNullException(nameof(clientId));
             TopicFilter = topicFilter ?? throw new ArgumentNullException(nameof(topicFilter));

Source/MQTTnet/Server/MqttServerClientUnsubscribedTopicHandlerDelegate.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading.Tasks;
+
+namespace MQTTnet.Server
+{
+    public class MqttServerClientUnsubscribedTopicHandlerDelegate : IMqttServerClientUnsubscribedTopicHandler
+    {
+        private readonly Func<MqttServerClientUnsubscribedTopicEventArgs, Task> _handler;
+
+        public MqttServerClientUnsubscribedTopicHandlerDelegate(Action<MqttServerClientUnsubscribedTopicEventArgs> handler)
+        {
+            if (handler == null) throw new ArgumentNullException(nameof(handler));
+
+            _handler = eventArgs =>
+            {
+                handler(eventArgs);
+                return Task.FromResult(0);
+            };
+        }
+
+        public MqttServerClientUnsubscribedTopicHandlerDelegate(Func<MqttServerClientUnsubscribedTopicEventArgs, Task> handler)
+        {
+            _handler = handler ?? throw new ArgumentNullException(nameof(handler));
+        }
+
+        public Task HandleClientUnsubscribedTopicAsync(MqttServerClientUnsubscribedTopicEventArgs eventArgs)
+        {
+            return _handler(eventArgs);
+        }
+    }
+}

Source/MQTTnet/Server/MqttServerEventDispatcher.cs

@@ -1,42 +1,73 @@
-using System;
+using System.Threading.Tasks;
+using MQTTnet.Client.Receiving;
 
 namespace MQTTnet.Server
 {
     public class MqttServerEventDispatcher
     {
-        public event EventHandler<MqttClientSubscribedTopicEventArgs> ClientSubscribedTopic;
+        public IMqttServerClientConnectedHandler ClientConnectedHandler { get; set; }
 
-        public event EventHandler<MqttClientUnsubscribedTopicEventArgs> ClientUnsubscribedTopic;
+        public IMqttServerClientDisconnectedHandler ClientDisconnectedHandler { get; set; }
 
-        public event EventHandler<MqttClientConnectedEventArgs> ClientConnected;
+        public IMqttServerClientSubscribedTopicHandler ClientSubscribedTopicHandler { get; set; }
 
-        public event EventHandler<MqttClientDisconnectedEventArgs> ClientDisconnected;
+        public IMqttServerClientUnsubscribedTopicHandler ClientUnsubscribedTopicHandler { get; set; }
 
-        public event EventHandler<MqttApplicationMessageReceivedEventArgs> ApplicationMessageReceived;
+        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler { get; set; }
 
-        public void OnClientSubscribedTopic(string clientId, TopicFilter topicFilter)
+        public Task HandleClientConnectedAsync(string clientId)
         {
-            ClientSubscribedTopic?.Invoke(this, new MqttClientSubscribedTopicEventArgs(clientId, topicFilter));
+            var handler = ClientConnectedHandler;
+            if (handler == null)
+            {
+                return Task.FromResult(0);
+            }
+
+            return handler.HandleClientConnectedAsync(new MqttServerClientConnectedEventArgs(clientId));
         }
 
-        public void OnClientUnsubscribedTopic(string clientId, string topicFilter)
+        public Task HandleClientDisconnectedAsync(string clientId, MqttClientDisconnectType disconnectType)
         {
-            ClientUnsubscribedTopic?.Invoke(this, new MqttClientUnsubscribedTopicEventArgs(clientId, topicFilter));
+            var handler = ClientDisconnectedHandler;
+            if (handler == null)
+            {
+                return Task.FromResult(0);
+            }
+
+            return handler.HandleClientDisconnectedAsync(new MqttServerClientDisconnectedEventArgs(clientId, disconnectType));
         }
 
-        public void OnClientDisconnected(string clientId, MqttClientDisconnectType disconnectType)
+        public Task HandleClientSubscribedTopicAsync(string clientId, TopicFilter topicFilter)
         {
-            ClientDisconnected?.Invoke(this, new MqttClientDisconnectedEventArgs(clientId, disconnectType));
+            var handler = ClientSubscribedTopicHandler;
+            if (handler == null)
+            {
+                return Task.FromResult(0);
+            }
+
+            return handler.HandleClientSubscribedTopicAsync(new MqttServerClientSubscribedTopicEventArgs(clientId, topicFilter));
         }
 
-        public void OnApplicationMessageReceived(string senderClientId, MqttApplicationMessage applicationMessage)
+        public Task HandleClientUnsubscribedTopicAsync(string clientId, string topicFilter)
         {
-            ApplicationMessageReceived?.Invoke(this, new MqttApplicationMessageReceivedEventArgs(senderClientId, applicationMessage));
+            var handler = ClientUnsubscribedTopicHandler;
+            if (handler == null)
+            {
+                return Task.FromResult(0);
+            }
+
+            return handler.HandleClientUnsubscribedTopicAsync(new MqttServerClientUnsubscribedTopicEventArgs(clientId, topicFilter));
         }
 
-        public void OnClientConnected(string clientId)
+        public Task HandleApplicationMessageReceivedAsync(string senderClientId, MqttApplicationMessage applicationMessage)
         {
-            ClientConnected?.Invoke(this, new MqttClientConnectedEventArgs(clientId));
+            var handler = ApplicationMessageReceivedHandler;
+            if (handler == null)
+            {
+                return Task.FromResult(0);
+            }
+
+            return handler.HandleApplicationMessageReceivedAsync(new MqttApplicationMessageReceivedEventArgs(senderClientId, applicationMessage));
         }
     }
 }

Source/MQTTnet/Server/MqttServerOptionsBuilder.cs

@@ -75,6 +75,12 @@ namespace MQTTnet.Server
             return this;
         }
 
+        public MqttServerOptionsBuilder WithEncryptedEndpointBoundIPV6Address(IPAddress value)
+        {
+            _options.TlsEndpointOptions.BoundInterNetworkV6Address = value;
+            return this;
+        }
+
         public MqttServerOptionsBuilder WithEncryptionCertificate(byte[] value)
         {
             _options.TlsEndpointOptions.Certificate = value;