Refactor event handler namings.

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;
 
@@ -7,8 +6,8 @@ namespace MQTTnet.Server
 {
     public interface IMqttServer : IApplicationMessageReceiver, IApplicationMessagePublisher
     {
-        event EventHandler Started;
-        event EventHandler Stopped;
+        IMqttServerStartedHandler StartedHandler { get; set; }
+        IMqttServerStoppedHandler StoppedHandler { get; set; }
 
         IMqttServerClientConnectedHandler ClientConnectedHandler { get; set; }
         IMqttServerClientDisconnectedHandler ClientDisconnectedHandler { get; set; }

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

@@ -369,7 +369,7 @@ namespace MQTTnet.Server
             ////    }
             ////});
 
-            await Task.FromResult(0);
+            //await Task.FromResult(0);
         }
 
         private async Task SendPendingPacketsAsync()

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))
@@ -313,8 +312,6 @@ 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/MqttServer.cs

@@ -30,8 +30,9 @@ namespace MQTTnet.Server
             _logger = logger.CreateChildLogger(nameof(MqttServer));
         }
 
-        public event EventHandler Started;
-        public event EventHandler Stopped;
+        public IMqttServerStartedHandler StartedHandler { get; set; }
+
+        public IMqttServerStoppedHandler StoppedHandler { get; set; }
 
         public IMqttServerClientConnectedHandler ClientConnectedHandler
         {
@@ -57,7 +58,7 @@ namespace MQTTnet.Server
             set => _eventDispatcher.ClientUnsubscribedTopicHandler = value;
         }
         
-        public IMqttApplicationMessageHandler ApplicationMessageReceivedHandler
+        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler
         {
             get => _eventDispatcher.ApplicationMessageReceivedHandler;
             set => _eventDispatcher.ApplicationMessageReceivedHandler = value;
@@ -128,7 +129,12 @@ namespace MQTTnet.Server
             }
 
             _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()
@@ -151,7 +157,6 @@ namespace MQTTnet.Server
                 }
 
                 _logger.Info("Stopped.");
-                Stopped?.Invoke(this, EventArgs.Empty);
             }
             finally
             {
@@ -163,6 +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()

Source/MQTTnet/Server/MqttServerEventDispatcher.cs

@@ -13,7 +13,7 @@ namespace MQTTnet.Server
 
         public IMqttServerClientUnsubscribedTopicHandler ClientUnsubscribedTopicHandler { get; set; }
 
-        public IMqttApplicationMessageHandler ApplicationMessageReceivedHandler { get; set; }
+        public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler { get; set; }
 
         public Task HandleClientConnectedAsync(string clientId)
         {
@@ -67,7 +67,7 @@ namespace MQTTnet.Server
                 return Task.FromResult(0);
             }
 
-            return handler.HandleApplicationMessageAsync(new MqttApplicationMessageReceivedEventArgs(senderClientId, applicationMessage));
+            return handler.HandleApplicationMessageReceivedAsync(new MqttApplicationMessageReceivedEventArgs(senderClientId, applicationMessage));
         }
     }
 }

Source/MQTTnet/Server/MqttServerStartedHandlerDelegate.cs

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

Source/MQTTnet/Server/MqttServerStoppedHandlerDelegate.cs

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