General code refactoring.

Build/MQTTnet.nuspec

@@ -12,9 +12,9 @@
     <requireLicenseAcceptance>true</requireLicenseAcceptance>
     <description>MQTTnet is a high performance .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker) and supports v3.1.0, v3.1.1 and v5.0.0 of the MQTT protocol.</description>
     <releaseNotes>
-* [Client] Fixed issue in keep alive handling.
-* [MQTTnet.Server] Added support for delivering static files (HTML, JavaScript etc.).
-* [MQTTnet.Server] Fixed web socket protocol errors (when using paho JS etc.).
+* [RcpClient] Adjusted some namespaces (BREAKING CHANGE!)
+* [AspNetCore] Adjusted some namespaces (BREAKING CHANGE!)
+* [Server] Adjusted some namespaces (BREAKING CHANGE!)
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2020</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 

Source/MQTTnet.AspnetCore/Extensions/ApplicationBuilderExtensions.cs

@@ -3,7 +3,7 @@ using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.DependencyInjection;
 using MQTTnet.Server;
 
-namespace MQTTnet.AspNetCore
+namespace MQTTnet.AspNetCore.Extensions
 {
     public static class ApplicationBuilderExtensions
     {

Source/MQTTnet.AspnetCore/Extensions/ConnectionBuilderExtensions.cs

@@ -1,6 +1,6 @@
 using Microsoft.AspNetCore.Connections;
 
-namespace MQTTnet.AspNetCore
+namespace MQTTnet.AspNetCore.Extensions
 {
     public static class ConnectionBuilderExtensions
     {

Source/MQTTnet.AspnetCore/Extensions/ConnectionRouteBuilderExtensions.cs

@@ -1,8 +1,11 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Connections;
+
+#if NETCOREAPP3_1
 using System;
+#endif
 
-namespace MQTTnet.AspNetCore
+namespace MQTTnet.AspNetCore.Extensions
 {
     public static class ConnectionRouteBuilderExtensions
     {

Source/MQTTnet.AspnetCore/Extensions/ReaderExtensions.cs

@@ -5,7 +5,7 @@ using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
 using MQTTnet.Packets;
 
-namespace MQTTnet.AspNetCore
+namespace MQTTnet.AspNetCore.Extensions
 {
     public static class ReaderExtensions
     {

Source/MQTTnet.AspnetCore/Extensions/ServiceCollectionExtensions.cs

@@ -1,12 +1,12 @@
-using Microsoft.Extensions.DependencyInjection;
+using System;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using MQTTnet.Adapter;
 using MQTTnet.Diagnostics;
 using MQTTnet.Implementations;
 using MQTTnet.Server;
-using System;
 
-namespace MQTTnet.AspNetCore
+namespace MQTTnet.AspNetCore.Extensions
 {
     public static class ServiceCollectionExtensions
     {

Source/MQTTnet.AspnetCore/MqttConnectionContext.cs

@@ -10,6 +10,7 @@ using System.IO.Pipelines;
 using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
+using MQTTnet.AspNetCore.Extensions;
 
 namespace MQTTnet.AspNetCore
 {

Source/MQTTnet.AspnetCore/SpanBasedMqttPacketBodyReader.cs

@@ -8,9 +8,9 @@ namespace MQTTnet.AspNetCore
 {
     public class SpanBasedMqttPacketBodyReader : IMqttPacketBodyReader
     {
-        private ReadOnlyMemory<byte> _buffer;
+        ReadOnlyMemory<byte> _buffer;
 
-        private int _offset;
+        int _offset;
         
         public void SetBuffer(ReadOnlyMemory<byte> buffer)
         {
@@ -38,16 +38,6 @@ namespace MQTTnet.AspNetCore
         {
             return ReadSegmentWithLengthPrefix().ToArray();
         }
-
-        private ReadOnlySpan<byte> ReadSegmentWithLengthPrefix()
-        {
-            var span = _buffer.Span;
-            var length = BinaryPrimitives.ReadUInt16BigEndian(span.Slice(_offset));
-
-            var result = span.Slice(_offset+2, length);
-            _offset += 2 + length;
-            return result;
-        }
         
         public unsafe string ReadStringWithLengthPrefix()
         {
@@ -121,5 +111,15 @@ namespace MQTTnet.AspNetCore
         {
             _offset = position;
         }
+
+        ReadOnlySpan<byte> ReadSegmentWithLengthPrefix()
+        {
+            var span = _buffer.Span;
+            var length = BinaryPrimitives.ReadUInt16BigEndian(span.Slice(_offset));
+
+            var result = span.Slice(_offset + 2, length);
+            _offset += 2 + length;
+            return result;
+        }
     }
 }

Source/MQTTnet.AspnetCore/SpanBasedMqttPacketWriter.cs

@@ -8,16 +8,10 @@ namespace MQTTnet.AspNetCore
 {
     public class SpanBasedMqttPacketWriter : IMqttPacketWriter
     {
-        private readonly ArrayPool<byte> _pool;
+        readonly ArrayPool<byte> _pool = ArrayPool<byte>.Create();
 
-        public SpanBasedMqttPacketWriter()
-        {
-            _pool = ArrayPool<byte>.Create();
-            
-        }
-
-        private byte[] _buffer;
-        private int _position;
+        byte[] _buffer;
+        int _position;
 
         public int Length { get; set; }
 
@@ -112,7 +106,7 @@ namespace MQTTnet.AspNetCore
             Commit(payload.Length);
         }
 
-        private void Commit(int count)
+        void Commit(int count)
         {
             if (_position == Length)
             {
@@ -122,7 +116,7 @@ namespace MQTTnet.AspNetCore
             _position += count;
         }
 
-        private void GrowIfNeeded(int requiredAdditional) 
+        void GrowIfNeeded(int requiredAdditional) 
         {
             var requiredTotal = _position + requiredAdditional;
             if (_buffer.Length >= requiredTotal)

Source/MQTTnet.Extensions.Rpc/Options/TopicGeneration/DefaultMqttRpcClientTopicGenerationStrategy.cs

@@ -1,7 +1,6 @@
-using MQTTnet.Extensions.Rpc.Options.TopicGeneration;
-using System;
+using System;
 
-namespace MQTTnet.Extensions.Rpc.Options
+namespace MQTTnet.Extensions.Rpc.Options.TopicGeneration
 {
     public class DefaultMqttRpcClientTopicGenerationStrategy : IMqttRpcClientTopicGenerationStrategy
     {

Source/MQTTnet.Server/.config/dotnet-tools.json

@@ -0,0 +1,12 @@
+{
+  "version": 1,
+  "isRoot": true,
+  "tools": {
+    "dotnet-ef": {
+      "version": "3.1.4",
+      "commands": [
+        "dotnet-ef"
+      ]
+    }
+  }
+}

Source/MQTTnet.Server/MQTTnet.Server.csproj

@@ -8,19 +8,22 @@
     <GeneratePackageOnBuild>False</GeneratePackageOnBuild>
     <Company />
     <Product>MQTTnet</Product>
-    <Description />
-    <Authors />
+    <Description>Standalone MQTT server with Python scripting backend.</Description>
+    <Authors>The authors of MQTTnet.Server.</Authors>
     <PackageId />
     <SignAssembly>false</SignAssembly>
     <DelaySign>false</DelaySign>
     <LangVersion>latest</LangVersion>
-    <Version>1.0.0</Version>
+    <Version>3.0.11</Version>
     <TypeScriptToolsVersion>3.3</TypeScriptToolsVersion>
   </PropertyGroup>
 
   <PropertyGroup>
     <StartupObject>MQTTnet.Server.Program</StartupObject>
     <UserSecretsId>c564f0de-28b4-45bf-b726-4d665d705653</UserSecretsId>
+    <Copyright>(c) Christian Kratky 2016-2020</Copyright>
+    <PackageProjectUrl>https://github.com/chkr1011/MQTTnet</PackageProjectUrl>
+    <RepositoryUrl>https://github.com/chkr1011/MQTTnet</RepositoryUrl>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">

Source/MQTTnet/Adapter/MqttChannelAdapter.cs

@@ -59,6 +59,7 @@ namespace MQTTnet.Adapter
         public async Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
             ThrowIfDisposed();
+            cancellationToken.ThrowIfCancellationRequested();
 
             try
             {
@@ -85,6 +86,7 @@ namespace MQTTnet.Adapter
         public async Task DisconnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
             ThrowIfDisposed();
+            cancellationToken.ThrowIfCancellationRequested();
 
             try
             {
@@ -112,8 +114,17 @@ namespace MQTTnet.Adapter
         public async Task SendPacketAsync(MqttBasePacket packet, TimeSpan timeout, CancellationToken cancellationToken)
         {
             ThrowIfDisposed();
+            cancellationToken.ThrowIfCancellationRequested();
+
+            try
+            {
+                await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
+            }
+            catch (ObjectDisposedException)
+            {
+                throw new OperationCanceledException();
+            }
 
-            await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
             try
             {
                 var packetData = PacketFormatterAdapter.Encode(packet);
@@ -144,13 +155,22 @@ namespace MQTTnet.Adapter
             finally
             {
                 PacketFormatterAdapter.FreeBuffer();
-                _writerSemaphore?.Release();
+
+                try
+                {
+                    _writerSemaphore.Release();
+                }
+                catch (ObjectDisposedException)
+                {
+                    throw new OperationCanceledException();
+                }
             }
         }
 
         public async Task<MqttBasePacket> ReceivePacketAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
             ThrowIfDisposed();
+            cancellationToken.ThrowIfCancellationRequested();
 
             try
             {
@@ -189,6 +209,9 @@ namespace MQTTnet.Adapter
             catch (OperationCanceledException)
             {
             }
+            catch (ObjectDisposedException)
+            {
+            }
             catch (Exception exception)
             {
                 if (IsWrappedException(exception))
@@ -212,8 +235,8 @@ namespace MQTTnet.Adapter
         {
             if (disposing)
             {
-                _channel?.Dispose();
-                _writerSemaphore?.Dispose();
+                _channel.Dispose();
+                _writerSemaphore.Dispose();
             }
 
             base.Dispose(disposing);

Source/MQTTnet/Implementations/CrossPlatformSocket.cs

@@ -20,7 +20,7 @@ namespace MQTTnet.Implementations
 
         public CrossPlatformSocket()
         {
-            // Having this contructor is important because avoiding the address family as parameter
+            // Having this constructor is important because avoiding the address family as parameter
             // will make use of dual mode in the .net framework.
             _socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
         }
@@ -33,75 +33,34 @@ namespace MQTTnet.Implementations
 
         public bool NoDelay
         {
-            get
-            {
-                return (int)_socket.GetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay) > 0;
-            }
-
-            set
-            {
-                _socket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, value ? 1 : 0);
-            }
+            get => (int)_socket.GetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay) > 0;
+            set => _socket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, value ? 1 : 0);
         }
 
         public bool DualMode
         {
-            get
-            {
-                return _socket.DualMode;
-            }
-
-            set
-            {
-                _socket.DualMode = value;
-            }
+            get => _socket.DualMode;
+            set => _socket.DualMode = value;
         }
 
         public int ReceiveBufferSize
         {
-            get
-            {
-                return _socket.ReceiveBufferSize;
-            }
-
-            set
-            {
-                _socket.ReceiveBufferSize = value;
-            }
+            get => _socket.ReceiveBufferSize;
+            set => _socket.ReceiveBufferSize = value;
         }
 
         public int SendBufferSize
         {
-            get
-            {
-                return _socket.SendBufferSize;
-            }
-
-            set
-            {
-                _socket.SendBufferSize = value;
-            }
+            get => _socket.SendBufferSize;
+            set => _socket.SendBufferSize = value;
         }
 
-        public EndPoint RemoteEndPoint
-        {
-            get
-            {
-                return _socket.RemoteEndPoint;
-            }
-        }
+        public EndPoint RemoteEndPoint => _socket.RemoteEndPoint;
 
         public bool ReuseAddress
         {
-            get
-            {
-                return (int)_socket.GetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress) != 0;
-            }
-
-            set
-            {
-                _socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, value ? 1 : 0);
-            }
+            get => (int)_socket.GetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress) != 0;
+            set => _socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, value ? 1 : 0);
         }
 
         public async Task<CrossPlatformSocket> AcceptAsync()

Source/MQTTnet/Implementations/MqttTcpChannel.Uwp.cs

@@ -17,14 +17,14 @@ using MQTTnet.Server;
 
 namespace MQTTnet.Implementations
 {
-    public class MqttTcpChannel : IMqttChannel
+    public sealed class MqttTcpChannel : IMqttChannel
     {
-        private readonly MqttClientTcpOptions _options;
-        private readonly int _bufferSize;
+        readonly MqttClientTcpOptions _options;
+        readonly int _bufferSize;
 
-        private StreamSocket _socket;
-        private Stream _readStream;
-        private Stream _writeStream;
+        StreamSocket _socket;
+        Stream _readStream;
+        Stream _writeStream;
 
         public MqttTcpChannel(IMqttClientOptions clientOptions)
         {

Source/MQTTnet/Implementations/MqttTcpChannel.cs

@@ -13,7 +13,7 @@ using System.Threading.Tasks;
 
 namespace MQTTnet.Implementations
 {
-    public sealed class MqttTcpChannel : IDisposable, IMqttChannel
+    public sealed class MqttTcpChannel : IMqttChannel
     {
         readonly IMqttClientOptions _clientOptions;
         readonly MqttClientTcpOptions _options;
@@ -162,7 +162,6 @@ namespace MQTTnet.Implementations
             }
             catch (ObjectDisposedException)
             {
-                return;
             }
             catch (IOException exception)
             {
@@ -205,7 +204,6 @@ namespace MQTTnet.Implementations
             {
                 return certificateValidationCallback(x509Certificate, chain, sslPolicyErrors, _clientOptions);
             }
-
 #endregion
 
             var certificateValidationHandler = _options?.TlsOptions?.CertificateValidationHandler;
@@ -229,7 +227,7 @@ namespace MQTTnet.Implementations
 
             if (chain.ChainStatus.Any(c => c.Status == X509ChainStatusFlags.RevocationStatusUnknown || c.Status == X509ChainStatusFlags.Revoked || c.Status == X509ChainStatusFlags.OfflineRevocation))
             {
-                if (!_options.TlsOptions.IgnoreCertificateRevocationErrors)
+                if (_options?.TlsOptions?.IgnoreCertificateRevocationErrors != true)
                 {
                     return false;
                 }
@@ -237,13 +235,13 @@ namespace MQTTnet.Implementations
 
             if (chain.ChainStatus.Any(c => c.Status == X509ChainStatusFlags.PartialChain))
             {
-                if (!_options.TlsOptions.IgnoreCertificateChainErrors)
+                if (_options?.TlsOptions?.IgnoreCertificateChainErrors != true)
                 {
                     return false;
                 }
             }
 
-            return _options.TlsOptions.AllowUntrustedCertificates;
+            return _options?.TlsOptions?.AllowUntrustedCertificates == true;
         }
 
         X509CertificateCollection LoadCertificates()

Source/MQTTnet/Implementations/MqttTcpServerAdapter.cs

@@ -130,7 +130,7 @@ namespace MQTTnet.Implementations
             }
         }
 
-        private Task OnClientAcceptedAsync(IMqttChannelAdapter channelAdapter)
+        Task OnClientAcceptedAsync(IMqttChannelAdapter channelAdapter)
         {
             var clientHandler = ClientHandler;
             if (clientHandler == null)

Source/MQTTnet/Implementations/MqttTcpServerListener.cs

@@ -24,8 +24,8 @@ namespace MQTTnet.Implementations
         readonly MqttServerTlsTcpEndpointOptions _tlsOptions;
         readonly X509Certificate2 _tlsCertificate;
 
-        private CrossPlatformSocket _socket;
-        private IPEndPoint _localEndPoint;
+        CrossPlatformSocket _socket;
+        IPEndPoint _localEndPoint;
 
         public MqttTcpServerListener(
             AddressFamily addressFamily,

Source/MQTTnet/Implementations/MqttWebSocketChannel.cs

@@ -35,7 +35,7 @@ namespace MQTTnet.Implementations
 
         public bool IsSecureConnection { get; private set; }
 
-        public X509Certificate2 ClientCertificate { get; private set; }
+        public X509Certificate2 ClientCertificate { get; }
 
         public async Task ConnectAsync(CancellationToken cancellationToken)
         {

Source/MQTTnet/Server/IMqttServerCertificateCredentials.cs

@@ -1,4 +1,7 @@
-public interface IMqttServerCertificateCredentials
+namespace MQTTnet.Server
 {
-    string Password { get; }
+    public interface IMqttServerCertificateCredentials
+    {
+        string Password { get; }
+    }
 }

Tests/MQTTnet.AspNetCore.Tests/MQTTnet.AspNetCore.Tests.csproj

@@ -6,13 +6,15 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.Hosting" Version="2.2.7" />
-    <PackageReference Include="Microsoft.AspNetCore.Server.Kestrel" Version="2.2.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.6.0" />
     <PackageReference Include="MSTest.TestAdapter" Version="2.1.1" />
     <PackageReference Include="MSTest.TestFramework" Version="2.1.1" />
   </ItemGroup>
 
+  <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp3.1' ">
+    <PackageReference Include="Microsoft.AspNetCore.Hosting" Version="2.2.7" />
+    <PackageReference Include="Microsoft.AspNetCore.Server.Kestrel" Version="2.2.0" />
+  </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' != 'netcoreapp3.1' ">
     <PackageReference Include="Microsoft.AspNetCore.Hosting" Version="2.1.1" />

Tests/MQTTnet.AspNetCore.Tests/MqttConnectionContextTest.cs

@@ -15,6 +15,7 @@ using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
 using MQTTnet.Packets;
 using System.Net;
+using MQTTnet.AspNetCore.Extensions;
 
 namespace MQTTnet.AspNetCore.Tests
 {

Tests/MQTTnet.AspNetCore.Tests/ReaderExtensionsTest.cs

@@ -1,6 +1,7 @@
-#if NETCOREAPP
+#if NETCOREAPP3_1
 using System.Buffers;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.AspNetCore.Extensions;
 using MQTTnet.Formatter;
 using MQTTnet.Packets;
 
@@ -31,7 +32,6 @@ namespace MQTTnet.AspNetCore.Tests
             result = serializer.TryDecode(reader, part, out packet, out consumed, out observed, out read);
             Assert.IsFalse(result);
 
-
             part = sequence.Slice(sequence.Start, 1); // partial fixed header should fail
             result = serializer.TryDecode(reader, part, out packet, out consumed, out observed, out read);
             Assert.IsFalse(result);

Tests/MQTTnet.Benchmarks/MessageProcessingMqttConnectionContextBenchmark.cs

@@ -9,6 +9,7 @@ using Microsoft.AspNetCore.Hosting;
 using MQTTnet.Server;
 using MQTTnet.Diagnostics;
 using MQTTnet.AspNetCore.Client;
+using MQTTnet.AspNetCore.Extensions;
 using MQTTnet.Client.Options;
 
 namespace MQTTnet.Benchmarks

Tests/MQTTnet.Core.Tests/Server_Tests.cs

@@ -274,6 +274,78 @@ namespace MQTTnet.Tests
             }
         }
 
+        [TestMethod]
+        public async Task Subscribe_Lots_In_Single_Request()
+        {
+            using (var testEnvironment = new TestEnvironment(TestContext))
+            {
+                var receivedMessagesCount = 0;
+
+                await testEnvironment.StartServerAsync();
+
+                var c1 = await testEnvironment.ConnectClientAsync();
+                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
+
+                var optionsBuilder = new MqttClientSubscribeOptionsBuilder();
+                for (var i = 0; i < 1000; i++)
+                {
+                    optionsBuilder.WithTopicFilter(i.ToString(), MqttQualityOfServiceLevel.AtMostOnce);
+                }
+
+                await c1.SubscribeAsync(optionsBuilder.Build()).ConfigureAwait(false);
+
+                var c2 = await testEnvironment.ConnectClientAsync();
+
+                var messageBuilder = new MqttApplicationMessageBuilder();
+                for (var i = 0; i < 1000; i++)
+                {
+                    messageBuilder.WithTopic(i.ToString());
+
+                    await c2.PublishAsync(messageBuilder.Build()).ConfigureAwait(false);
+                }
+
+                await Task.Delay(500).ConfigureAwait(false);
+
+                Assert.AreEqual(1000, receivedMessagesCount);
+            }
+        }
+
+        [TestMethod]
+        public async Task Subscribe_Lots_In_Multiple_Requests()
+        {
+            using (var testEnvironment = new TestEnvironment(TestContext))
+            {
+                var receivedMessagesCount = 0;
+
+                await testEnvironment.StartServerAsync();
+
+                var c1 = await testEnvironment.ConnectClientAsync();
+                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
+
+                for (var i = 0; i < 1000; i++)
+                {
+                    var so = new MqttClientSubscribeOptionsBuilder()
+                        .WithTopicFilter(i.ToString(), MqttQualityOfServiceLevel.AtMostOnce).Build();
+
+                    await c1.SubscribeAsync(so).ConfigureAwait(false);
+                }
+                
+                var c2 = await testEnvironment.ConnectClientAsync();
+
+                var messageBuilder = new MqttApplicationMessageBuilder();
+                for (var i = 0; i < 1000; i++)
+                {
+                    messageBuilder.WithTopic(i.ToString());
+
+                    await c2.PublishAsync(messageBuilder.Build()).ConfigureAwait(false);
+                }
+
+                await Task.Delay(500).ConfigureAwait(false);
+
+                Assert.AreEqual(1000, receivedMessagesCount);
+            }
+        }
+
         [TestMethod]
         public async Task Subscribe_Multiple_In_Multiple_Request()
         {

Tests/MQTTnet.TestApp.AspNetCore2/Program.cs

@@ -2,6 +2,7 @@
 using Microsoft.AspNetCore.Hosting;
 using MQTTnet.AspNetCore;
 using System.Threading.Tasks;
+using MQTTnet.AspNetCore.Extensions;
 
 namespace MQTTnet.TestApp.AspNetCore2
 {

Tests/MQTTnet.TestApp.AspNetCore2/Startup.cs

@@ -9,6 +9,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.FileProviders;
 using Microsoft.Extensions.Logging;
 using MQTTnet.AspNetCore;
+using MQTTnet.AspNetCore.Extensions;
 using MQTTnet.Server;
 
 namespace MQTTnet.TestApp.AspNetCore2