Add support for retained application messages

MQTTnet.Core/Adapter/IMqttServerAdapter.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 using MQTTnet.Core.Server;
 
 namespace MQTTnet.Core.Adapter
@@ -7,8 +8,7 @@ namespace MQTTnet.Core.Adapter
     {
         event EventHandler<MqttClientConnectedEventArgs> ClientConnected;
 
-        void Start(MqttServerOptions options);
-
-        void Stop();
+        Task StartAsync(MqttServerOptions options);
+        Task StopAsync();
     }
 }

MQTTnet.Core/Adapter/MqttChannelCommunicationAdapter.cs

@@ -36,6 +36,10 @@ namespace MQTTnet.Core.Adapter
             {
                 throw;
             }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
             catch (MqttCommunicationTimedOutException)
             {
                 throw;
@@ -60,6 +64,10 @@ namespace MQTTnet.Core.Adapter
             {
                 throw;
             }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
             catch (MqttCommunicationTimedOutException)
             {
                 throw;
@@ -87,7 +95,7 @@ namespace MQTTnet.Core.Adapter
                         continue;
                     }
 
-                    MqttTrace.Information(nameof(MqttChannelCommunicationAdapter), $"TX >>> {0} [Timeout={1}]", packet, timeout);
+                    MqttTrace.Information(nameof(MqttChannelCommunicationAdapter), "TX >>> {0} [Timeout={1}]", packet, timeout);
 
                     var writeBuffer = PacketSerializer.Serialize(packet);
                     await _channel.SendStream.WriteAsync(writeBuffer, 0, writeBuffer.Length, cancellationToken).ConfigureAwait(false);
@@ -106,6 +114,10 @@ namespace MQTTnet.Core.Adapter
             {
                 throw;
             }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
             catch (MqttCommunicationTimedOutException)
             {
                 throw;
@@ -156,6 +168,10 @@ namespace MQTTnet.Core.Adapter
             {
                 throw;
             }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
             catch (MqttCommunicationTimedOutException)
             {
                 throw;

MQTTnet.Core/Adapter/MqttClientDisconnectedEventArgs.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace MQTTnet.Core.Adapter
+{
+    public class MqttClientDisconnectedEventArgs : EventArgs
+    {
+        public MqttClientDisconnectedEventArgs(string identifier, IMqttCommunicationAdapter clientAdapter)
+        {
+            Identifier = identifier ?? throw new ArgumentNullException(nameof(identifier));
+            ClientAdapter = clientAdapter ?? throw new ArgumentNullException(nameof(clientAdapter));
+        }
+
+        public string Identifier { get; }
+
+        public IMqttCommunicationAdapter ClientAdapter { get; }
+    }
+}