Restore interfaces.

Source/MQTTnet.Benchmarks/MessageDeliveryBenchmark.cs

@@ -37,8 +37,8 @@ namespace MQTTnet.Benchmarks
         CancellationTokenSource _cancellationTokenSource;
 
         MqttServer _mqttServer;
-        List<MQTTnet.Client.MqttClient> _mqttSubscriberClients;
+        List<IMqttClient> _mqttSubscriberClients;
-        Dictionary<string, MQTTnet.Client.MqttClient> _mqttPublisherClientsByPublisherName;
+        Dictionary<string, IMqttClient> _mqttPublisherClientsByPublisherName;
 
         Dictionary<string, List<string>> _topicsByPublisher;
         Dictionary<string, string> _publisherByTopic;        
@@ -74,7 +74,7 @@ namespace MQTTnet.Benchmarks
             _mqttServer.StartAsync().GetAwaiter().GetResult();
 
             // Create publisher clients
-            _mqttPublisherClientsByPublisherName = new Dictionary<string, MQTTnet.Client.MqttClient>();
+            _mqttPublisherClientsByPublisherName = new Dictionary<string, IMqttClient>();
             foreach (var pt in _topicsByPublisher)
             {
                 var publisherName = pt.Key;
@@ -89,7 +89,7 @@ namespace MQTTnet.Benchmarks
             }
 
             // Create subscriber clients
-            _mqttSubscriberClients = new List<MQTTnet.Client.MqttClient>();
+            _mqttSubscriberClients = new List<IMqttClient>();
             for (var i = 0; i < NumSubscribers; i++)
             {
                 var mqttSubscriberClient = factory.CreateMqttClient();

Source/MQTTnet.Benchmarks/MessageProcessingBenchmark.cs

@@ -16,7 +16,7 @@ namespace MQTTnet.Benchmarks
     public class MessageProcessingBenchmark
     {
         MqttServer _mqttServer;
-        MqttClient _mqttClient;
+        IMqttClient _mqttClient;
         MqttApplicationMessage _message;
 
         [GlobalSetup]

Source/MQTTnet.Benchmarks/MessageProcessingMqttConnectionContextBenchmark.cs

@@ -18,7 +18,7 @@ namespace MQTTnet.Benchmarks
     public class MessageProcessingMqttConnectionContextBenchmark
     {
         IWebHost _host;
-        MqttClient _mqttClient;
+        IMqttClient _mqttClient;
         MqttApplicationMessage _message;
 
         [GlobalSetup]

Source/MQTTnet.Benchmarks/SubscribeBenchmark.cs

@@ -11,7 +11,7 @@ namespace MQTTnet.Benchmarks
     public class SubscribeBenchmark
     {
         MqttServer _mqttServer;
-        MQTTnet.Client.MqttClient _mqttClient;
+        IMqttClient _mqttClient;
 
         const int NumPublishers = 1;
         const int NumTopicsPerPublisher = 10000;
@@ -54,6 +54,7 @@ namespace MQTTnet.Benchmarks
                 var subscribeOptions = new MqttClientSubscribeOptionsBuilder()
                        .WithTopicFilter(topic, Protocol.MqttQualityOfServiceLevel.AtMostOnce)
                        .Build();
+                
                 _mqttClient.SubscribeAsync(subscribeOptions).GetAwaiter().GetResult();
             }
         }

Source/MQTTnet.Benchmarks/UnsubscribeBenchmark.cs

@@ -1,5 +1,4 @@
 using BenchmarkDotNet.Attributes;
-using BenchmarkDotNet.Jobs;
 using MQTTnet.Client;
 using MQTTnet.Server;
 using System.Collections.Generic;
@@ -11,7 +10,7 @@ namespace MQTTnet.Benchmarks
     public class UnsubscribeBenchmark
     {
         MqttServer _mqttServer;
-        MQTTnet.Client.MqttClient _mqttClient;
+        IMqttClient _mqttClient;
 
         const int NumPublishers = 1;
         const int NumTopicsPerPublisher = 10000;
@@ -40,7 +39,7 @@ namespace MQTTnet.Benchmarks
             foreach (var topic in _topics)
             {
                 var subscribeOptions = new MqttClientSubscribeOptionsBuilder()
-                       .WithTopicFilter(topic, Protocol.MqttQualityOfServiceLevel.AtMostOnce)
+                       .WithTopicFilter(topic)
                        .Build();
                 _mqttClient.SubscribeAsync(subscribeOptions).GetAwaiter().GetResult();
             }

Source/MQTTnet.Extensions.ManagedClient/IManagedMqttClient.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Client;
+using MQTTnet.Packets;
+
+namespace MQTTnet.Extensions.ManagedClient
+{
+    public interface IManagedMqttClient : IDisposable
+    {
+        event Func<ApplicationMessageProcessedEventArgs, Task> ApplicationMessageProcessedAsync;
+        
+        event Func<MqttApplicationMessageReceivedEventArgs, Task> ApplicationMessageReceivedAsync;
+        
+        event Func<EventArgs, Task> ConnectedAsync;
+        
+        event Func<ConnectingFailedEventArgs, Task> ConnectingFailedAsync;
+        
+        event Func<EventArgs, Task> ConnectionStateChangedAsync;
+        
+        event Func<EventArgs, Task> DisconnectedAsync;
+        
+        IApplicationMessageSkippedHandler ApplicationMessageSkippedHandler { get; set; }
+        
+        IMqttClient InternalClient { get; }
+        
+        bool IsConnected { get; }
+        
+        bool IsStarted { get; }
+        
+        ManagedMqttClientOptions Options { get; }
+        
+        int PendingApplicationMessagesCount { get; }
+        
+        ISynchronizingSubscriptionsFailedHandler SynchronizingSubscriptionsFailedHandler { get; set; }
+        
+        Task EnqueueAsync(MqttApplicationMessage applicationMessage);
+        
+        Task EnqueueAsync(ManagedMqttApplicationMessage applicationMessage);
+        
+        Task PingAsync(CancellationToken cancellationToken = default);
+        
+        Task StartAsync(ManagedMqttClientOptions options);
+        
+        Task StopAsync();
+        
+        Task SubscribeAsync(ICollection<MqttTopicFilter> topicFilters);
+        
+        Task UnsubscribeAsync(ICollection<string> topics);
+    }
+}

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs

@@ -14,11 +14,10 @@ using MQTTnet.Internal;
 using MQTTnet.Packets;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
-using MqttClient = MQTTnet.Client.MqttClient;
 
 namespace MQTTnet.Extensions.ManagedClient
 {
-    public sealed class ManagedMqttClient : Disposable
+    public sealed class ManagedMqttClient : Disposable, IManagedMqttClient
     {
         readonly AsyncEvent<ApplicationMessageProcessedEventArgs> _applicationMessageProcessedEvent = new AsyncEvent<ApplicationMessageProcessedEventArgs>();
         readonly AsyncEvent<ConnectingFailedEventArgs> _connectingFailedEvent = new AsyncEvent<ConnectingFailedEventArgs>();
@@ -62,7 +61,7 @@ namespace MQTTnet.Extensions.ManagedClient
 
         ManagedMqttClientStorageManager _storageManager;
 
-        public ManagedMqttClient(MqttClient mqttClient, IMqttNetLogger logger)
+        public ManagedMqttClient(IMqttClient mqttClient, IMqttNetLogger logger)
         {
             InternalClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
 
@@ -112,7 +111,7 @@ namespace MQTTnet.Extensions.ManagedClient
 
         public IApplicationMessageSkippedHandler ApplicationMessageSkippedHandler { get; set; }
 
-        public MqttClient InternalClient { get; }
+        public IMqttClient InternalClient { get; }
 
         public bool IsConnected => InternalClient.IsConnected;
 
@@ -203,7 +202,7 @@ namespace MQTTnet.Extensions.ManagedClient
             }
         }
 
-        public Task PingAsync(CancellationToken cancellationToken)
+        public Task PingAsync(CancellationToken cancellationToken = default)
         {
             return InternalClient.PingAsync(cancellationToken);
         }

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClientExtensions.cs

@@ -13,7 +13,7 @@ namespace MQTTnet.Extensions.ManagedClient
     public static class ManagedMqttClientExtensions
     {
         public static Task EnqueueAsync(
-            this ManagedMqttClient managedMqttClient,
+            this IManagedMqttClient managedMqttClient,
             string topic,
             string payload = null,
             MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce,
@@ -39,7 +39,7 @@ namespace MQTTnet.Extensions.ManagedClient
         }
 
         public static Task SubscribeAsync(
-            this ManagedMqttClient managedMqttClient,
+            this IManagedMqttClient managedMqttClient,
             string topic,
             MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce)
         {
@@ -60,7 +60,7 @@ namespace MQTTnet.Extensions.ManagedClient
                 });
         }
 
-        public static Task UnsubscribeAsync(this ManagedMqttClient managedMqttClient, string topic)
+        public static Task UnsubscribeAsync(this IManagedMqttClient managedMqttClient, string topic)
         {
             if (managedMqttClient == null)
             {

Source/MQTTnet.Extensions.ManagedClient/MqttFactoryExtensions.cs

@@ -10,7 +10,7 @@ namespace MQTTnet.Extensions.ManagedClient
 {
     public static class MqttFactoryExtensions
     {
-        public static ManagedMqttClient CreateManagedMqttClient(this MqttFactory factory, MqttClient mqttClient = null)
+        public static IManagedMqttClient CreateManagedMqttClient(this MqttFactory factory, IMqttClient mqttClient = null)
         {
             if (factory == null) throw new ArgumentNullException(nameof(factory));
 
@@ -22,7 +22,7 @@ namespace MQTTnet.Extensions.ManagedClient
             return new ManagedMqttClient(mqttClient, factory.DefaultLogger);
         }
         
-        public static ManagedMqttClient CreateManagedMqttClient(this MqttFactory factory, IMqttNetLogger logger)
+        public static IManagedMqttClient CreateManagedMqttClient(this MqttFactory factory, IMqttNetLogger logger)
         {
             if (factory == null) throw new ArgumentNullException(nameof(factory));
             if (logger == null) throw new ArgumentNullException(nameof(logger));

Source/MQTTnet.Extensions.Rpc/IMqttRpcClient.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Protocol;
+
+namespace MQTTnet.Extensions.Rpc
+{
+    public interface IMqttRpcClient : IDisposable
+    {
+        Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel);
+        
+        Task<byte[]> ExecuteAsync(string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, CancellationToken cancellationToken = default);
+    }
+}

Source/MQTTnet.Extensions.Rpc/MqttFactoryExtensions.cs

@@ -9,7 +9,7 @@ namespace MQTTnet.Extensions.Rpc
 {
     public static class MqttFactoryExtensions
     {
-        public static MqttRpcClient CreateMqttRpcClient(this MqttFactory factory, MqttClient mqttClient)
+        public static IMqttRpcClient CreateMqttRpcClient(this MqttFactory factory, IMqttClient mqttClient)
         {
             return factory.CreateMqttRpcClient(mqttClient, new MqttRpcClientOptions
             {
@@ -17,10 +17,8 @@ namespace MQTTnet.Extensions.Rpc
             });
         }
 
-        public static MqttRpcClient CreateMqttRpcClient(this MqttFactory factory, MqttClient mqttClient, MqttRpcClientOptions rpcClientOptions)
+        public static IMqttRpcClient CreateMqttRpcClient(this MqttFactory _, IMqttClient mqttClient, MqttRpcClientOptions rpcClientOptions)
         {
-            if (factory == null) throw new ArgumentNullException(nameof(factory));
-            
             if (mqttClient == null)
             {
                 throw new ArgumentNullException(nameof(mqttClient));

Source/MQTTnet.Extensions.Rpc/MqttRpcClient.cs

@@ -13,13 +13,13 @@ using MQTTnet.Implementations;
 
 namespace MQTTnet.Extensions.Rpc
 {
-    public sealed class MqttRpcClient : IDisposable
+    public sealed class MqttRpcClient : IMqttRpcClient
     {
         readonly ConcurrentDictionary<string, TaskCompletionSource<byte[]>> _waitingCalls = new ConcurrentDictionary<string, TaskCompletionSource<byte[]>>();
-        readonly MqttClient _mqttClient;
+        readonly IMqttClient _mqttClient;
         readonly MqttRpcClientOptions _options;
         
-        public MqttRpcClient(MqttClient mqttClient, MqttRpcClientOptions options)
+        public MqttRpcClient(IMqttClient mqttClient, MqttRpcClientOptions options)
         {
             _mqttClient = mqttClient ?? throw new ArgumentNullException(nameof(mqttClient));
             _options = options ?? throw new ArgumentNullException(nameof(options));
@@ -47,7 +47,7 @@ namespace MQTTnet.Extensions.Rpc
             }
         }
 
-        public async Task<byte[]> ExecuteAsync(string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, CancellationToken cancellationToken)
+        public async Task<byte[]> ExecuteAsync(string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, CancellationToken cancellationToken = default)
         {
             if (methodName == null) throw new ArgumentNullException(nameof(methodName));
             

Source/MQTTnet.Extensions.Rpc/MqttRpcClientExtensions.cs

@@ -11,7 +11,7 @@ namespace MQTTnet.Extensions.Rpc
 {
     public static class MqttRpcClientExtensions
     {
-        public static Task<byte[]> ExecuteAsync(this MqttRpcClient client, TimeSpan timeout, string methodName, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
+        public static Task<byte[]> ExecuteAsync(this IMqttRpcClient client, TimeSpan timeout, string methodName, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
         {
             if (client == null) throw new ArgumentNullException(nameof(client));
 

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

@@ -21,7 +21,7 @@ namespace MQTTnet.Extensions.Rpc
         /// </summary>
         public MqttQualityOfServiceLevel QualityOfServiceLevel { get; set; }
 
-        public MqttClient MqttClient { get; set; }
+        public IMqttClient MqttClient { get; set; }
 
         public MqttRpcClientOptions Options { get; set; }
     }

Source/MQTTnet.TestApp/MessageThroughputTest.cs

@@ -33,8 +33,8 @@ namespace MQTTnet.TestApp
         CancellationTokenSource _cancellationTokenSource;
 
         MqttServer _mqttServer;
-        Dictionary<string, Client.MqttClient> _mqttPublisherClientsByPublisherName;
+        Dictionary<string, IMqttClient> _mqttPublisherClientsByPublisherName;
-        List<Client.MqttClient> _mqttSubscriberClients;
+        List<IMqttClient> _mqttSubscriberClients;
 
         Dictionary<string, List<string>> _topicsByPublisher;
         Dictionary<string, List<string>> _singleWildcardTopicsByPublisher;
@@ -85,7 +85,7 @@ namespace MQTTnet.TestApp
 
             var stopWatch = new System.Diagnostics.Stopwatch();
             stopWatch.Start();
-            _mqttPublisherClientsByPublisherName = new Dictionary<string, Client.MqttClient>();
+            _mqttPublisherClientsByPublisherName = new Dictionary<string, IMqttClient>();
             foreach (var pt in _topicsByPublisher)
             {
                 var publisherName = pt.Key;
@@ -99,10 +99,10 @@ namespace MQTTnet.TestApp
             }
             stopWatch.Stop();
 
-            Console.Write(string.Format("{0} publisher(s) connected in {1:0.000} seconds, ", NumPublishers, stopWatch.ElapsedMilliseconds / 1000.0));
+            Console.Write($"{NumPublishers} publisher(s) connected in {stopWatch.ElapsedMilliseconds / 1000.0:0.000} seconds, ");
-            Console.WriteLine(string.Format("connections per second: {0:0.000}", NumPublishers / (stopWatch.ElapsedMilliseconds / 1000.0)));
+            Console.WriteLine($"connections per second: {NumPublishers / (stopWatch.ElapsedMilliseconds / 1000.0):0.000}");
 
-            _mqttSubscriberClients = new List<Client.MqttClient>();
+            _mqttSubscriberClients = new List<IMqttClient>();
             for (var i = 0; i < NumSubscribers; ++i)
             {
                 var mqttClient = factory.CreateMqttClient();
@@ -147,7 +147,6 @@ namespace MQTTnet.TestApp
             _mqttServer.Dispose();
         }
 
-
         /// <summary>
         /// Measure no-wildcard topic subscription message exchange performance
         /// </summary>
@@ -174,16 +173,16 @@ namespace MQTTnet.TestApp
 
 
         /// <summary>
-        ///  Subcribe to all topics, then run message exchange
+        ///  Subscribe to all topics, then run message exchange
         /// </summary>
         public async Task ProcessMessages(Dictionary<string, List<string>> topicsByPublisher, string topicTypeDescription)
         {
             var numTopics = CountTopics(topicsByPublisher);
 
             Console.WriteLine();
-            Console.Write(string.Format("Subscribing to {0} topics ", numTopics));
+            Console.Write($"Subscribing to {numTopics} topics ");
-            ConsoleWriteInfo(string.Format("({0})", topicTypeDescription));
+            ConsoleWriteInfo($"({topicTypeDescription})");
-            Console.WriteLine(string.Format(" for {0} subscriber(s)...", NumSubscribers));
+            Console.WriteLine($" for {NumSubscribers} subscriber(s)...");
 
             var stopWatch = new System.Diagnostics.Stopwatch();
             stopWatch.Start();
@@ -204,12 +203,12 @@ namespace MQTTnet.TestApp
 
             stopWatch.Stop();
 
-            Console.Write(string.Format("{0} subscriber(s) subscribed in {1:0.000} seconds, ", NumSubscribers, stopWatch.ElapsedMilliseconds / 1000.0));
+            Console.Write($"{NumSubscribers} subscriber(s) subscribed in {stopWatch.ElapsedMilliseconds / 1000.0:0.000} seconds, ");
-            Console.WriteLine(string.Format("subscribe calls per second: {0:0.000}", numTopics / (stopWatch.ElapsedMilliseconds / 1000.0)));
+            Console.WriteLine($"subscribe calls per second: {numTopics / (stopWatch.ElapsedMilliseconds / 1000.0):0.000}");
 
             await PublishAllAsync();
 
-            Console.WriteLine(string.Format("Unsubscribing {0} topics ({1}) for {2} subscriber(s)...", numTopics, topicTypeDescription, NumSubscribers));
+            Console.WriteLine($"Unsubscribing {numTopics} topics ({topicTypeDescription}) for {NumSubscribers} subscriber(s)...");
 
             stopWatch.Restart();
 
@@ -234,11 +233,10 @@ namespace MQTTnet.TestApp
 
             stopWatch.Stop();
 
-            Console.Write(string.Format("{0} subscriber(s) unsubscribed in {1:0.000} seconds, ", NumSubscribers, stopWatch.ElapsedMilliseconds / 1000.0));
+            Console.Write($"{NumSubscribers} subscriber(s) unsubscribed in {stopWatch.ElapsedMilliseconds / 1000.0:0.000} seconds, ");
-            Console.WriteLine(string.Format("unsubscribe calls per second: {0:0.000}", numTopics / (stopWatch.ElapsedMilliseconds / 1000.0)));
+            Console.WriteLine($"unsubscribe calls per second: {numTopics / (stopWatch.ElapsedMilliseconds / 1000.0):0.000}");
         }
 
-
         /// <summary>
         /// Publish messages in batches of NumPublishCallsPerBatch, wait for messages sent to subscriber
         /// </summary>
@@ -289,7 +287,6 @@ namespace MQTTnet.TestApp
                 }
                 catch
                 {
-
                 }
 
                 _cancellationTokenSource.Dispose();
@@ -305,8 +302,8 @@ namespace MQTTnet.TestApp
 
             stopWatch.Stop();
 
-            System.Console.Write(string.Format("{0} messages published and received in {1:0.000} seconds, ", totalNumMessagesReceived, stopWatch.ElapsedMilliseconds / 1000.0));
+            Console.Write($"{totalNumMessagesReceived} messages published and received in {stopWatch.ElapsedMilliseconds / 1000.0:0.000} seconds, ");
-            ConsoleWriteLineSuccess(string.Format("messages per second: {0}", (int)(totalNumMessagesReceived / (stopWatch.ElapsedMilliseconds / 1000.0))));
+            ConsoleWriteLineSuccess($"messages per second: {(int)(totalNumMessagesReceived / (stopWatch.ElapsedMilliseconds / 1000.0))}");
         }
 
         int CountTopics(Dictionary<string, List<string>> topicsByPublisher)

Source/MQTTnet.TestApp/PerformanceTest.cs

@@ -201,7 +201,7 @@ namespace MQTTnet.TestApp
             };
         }
 
-        static Task PublishSingleMessage(MqttClient client, MqttApplicationMessage applicationMessage, ref int count)
+        static Task PublishSingleMessage(IMqttClient client, MqttApplicationMessage applicationMessage, ref int count)
         {
             Interlocked.Increment(ref count);
             return Task.Run(() => client.PublishAsync(applicationMessage));

Source/MQTTnet.Tests/Client/LowLevelMqttClient_Tests.cs

@@ -177,7 +177,7 @@ namespace MQTTnet.Tests.Client
             }
         }
 
-        async Task<MqttConnAckPacket> Authenticate(LowLevelMqttClient client)
+        async Task<MqttConnAckPacket> Authenticate(ILowLevelMqttClient client)
         {
             await client.SendAsync(
                     new MqttConnectPacket
@@ -193,7 +193,7 @@ namespace MQTTnet.Tests.Client
             return await client.ReceiveAsync(CancellationToken.None).ConfigureAwait(false) as MqttConnAckPacket;
         }
 
-        async Task<MqttSubAckPacket> Subscribe(LowLevelMqttClient client, string topic)
+        async Task<MqttSubAckPacket> Subscribe(ILowLevelMqttClient client, string topic)
         {
             await client.SendAsync(
                     new MqttSubscribePacket

Source/MQTTnet.Tests/Client/ManagedMqttClient_Tests.cs

@@ -389,7 +389,7 @@ namespace MQTTnet.Tests.Client
 
         async Task<ManagedMqttClient> CreateManagedClientAsync(
             TestEnvironment testEnvironment,
-            MqttClient underlyingClient = null,
+            IMqttClient underlyingClient = null,
             TimeSpan? connectionCheckInterval = null,
             string host = "localhost")
         {

Source/MQTTnet.Tests/Client/MqttClient_Tests.cs

@@ -226,7 +226,7 @@ namespace MQTTnet.Tests.Client
             {
                 await testEnvironment.StartServer();
 
-                var clients = new List<MqttClient>();
+                var clients = new List<IMqttClient>();
                 for (var i = 0; i < 100; i++)
                 {
                     clients.Add(await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithClientId("a")));

Source/MQTTnet.Tests/Formatter/MqttPacketSerialization_V3_Tests.cs

@@ -204,7 +204,7 @@ namespace MQTTnet.Tests
         {
             var disconnectPacket = new MqttDisconnectPacket
             {
-                ReasonCode = MqttDisconnectReasonCode.NormalDisconnection,
+                ReasonCode = MqttDisconnectReasonCode.NormalDisconnection, // MQTTv3 has no other values than this.
                 ReasonString = "ReasonString",
                 ServerReference = "ServerReference",
                 SessionExpiryInterval = 234,
@@ -216,7 +216,6 @@ namespace MQTTnet.Tests
 
             var deserialized = MqttPacketSerializationHelper.EncodeAndDecodePacket(disconnectPacket, MqttProtocolVersion.V311);
 
-            
             Assert.AreEqual(disconnectPacket.ReasonCode, deserialized.ReasonCode);
             Assert.AreEqual(null, deserialized.ReasonString); // Not supported in v3.1.1
             Assert.AreEqual(null, deserialized.ServerReference); // Not supported in v3.1.1

Source/MQTTnet.Tests/Formatter/MqttPacketSerialization_V5_Tests.cs

@@ -166,7 +166,7 @@ namespace MQTTnet.Tests
         {
             var disconnectPacket = new MqttDisconnectPacket
             {
-                ReasonCode = MqttDisconnectReasonCode.NormalDisconnection,
+                ReasonCode = MqttDisconnectReasonCode.QuotaExceeded,
                 ReasonString = "ReasonString",
                 ServerReference = "ServerReference",
                 SessionExpiryInterval = 234,

Source/MQTTnet.Tests/Mockups/TestApplicationMessageReceivedHandler.cs

@@ -15,7 +15,7 @@ namespace MQTTnet.Tests.Mockups
     {
         readonly List<MqttApplicationMessageReceivedEventArgs> _receivedEventArgs = new List<MqttApplicationMessageReceivedEventArgs>();
 
-        public TestApplicationMessageReceivedHandler(MqttClient mqttClient)
+        public TestApplicationMessageReceivedHandler(IMqttClient mqttClient)
         {
             mqttClient.ApplicationMessageReceivedAsync += MqttClientOnApplicationMessageReceivedAsync;
         }

Source/MQTTnet.Tests/Mockups/TestEnvironment.cs

@@ -17,17 +17,16 @@ using MQTTnet.Implementations;
 using MQTTnet.LowLevelClient;
 using MQTTnet.Protocol;
 using MQTTnet.Server;
-using MqttClient = MQTTnet.Client.MqttClient;
 
 namespace MQTTnet.Tests.Mockups
 {
     public sealed class TestEnvironment : IDisposable
     {
         readonly List<string> _clientErrors = new List<string>();
-        readonly List<MqttClient> _clients = new List<MqttClient>();
+        readonly List<IMqttClient> _clients = new List<IMqttClient>();
 
         readonly List<Exception> _exceptions = new List<Exception>();
-        readonly List<LowLevelMqttClient> _lowLevelClients = new List<LowLevelMqttClient>();
+        readonly List<ILowLevelMqttClient> _lowLevelClients = new List<ILowLevelMqttClient>();
         readonly MqttProtocolVersion _protocolVersion;
         readonly List<string> _serverErrors = new List<string>();
 
@@ -91,12 +90,12 @@ namespace MQTTnet.Tests.Mockups
 
         public TestContext TestContext { get; }
 
-        public Task<MqttClient> ConnectClient()
+        public Task<IMqttClient> ConnectClient()
         {
             return ConnectClient(Factory.CreateClientOptionsBuilder().WithProtocolVersion(_protocolVersion));
         }
 
-        public async Task<MqttClient> ConnectClient(Action<MqttClientOptionsBuilder> configureOptions, TimeSpan timeout = default)
+        public async Task<IMqttClient> ConnectClient(Action<MqttClientOptionsBuilder> configureOptions, TimeSpan timeout = default)
         {
             if (configureOptions == null)
             {
@@ -128,7 +127,7 @@ namespace MQTTnet.Tests.Mockups
             return client;
         }
 
-        public async Task<MqttClient> ConnectClient(MqttClientOptionsBuilder options, TimeSpan timeout = default)
+        public async Task<IMqttClient> ConnectClient(MqttClientOptionsBuilder options, TimeSpan timeout = default)
         {
             if (options == null)
             {
@@ -154,7 +153,7 @@ namespace MQTTnet.Tests.Mockups
             return client;
         }
 
-        public async Task<MqttClient> ConnectClient(MqttClientOptions options, TimeSpan timeout = default)
+        public async Task<IMqttClient> ConnectClient(MqttClientOptions options, TimeSpan timeout = default)
         {
             if (options == null)
             {
@@ -178,7 +177,7 @@ namespace MQTTnet.Tests.Mockups
             return client;
         }
 
-        public async Task<LowLevelMqttClient> ConnectLowLevelClient(Action<MqttClientOptionsBuilder> optionsBuilder = null)
+        public async Task<ILowLevelMqttClient> ConnectLowLevelClient(Action<MqttClientOptionsBuilder> optionsBuilder = null)
         {
             var options = new MqttClientOptionsBuilder();
             options = options.WithTcpServer("127.0.0.1", ServerPort);
@@ -195,12 +194,12 @@ namespace MQTTnet.Tests.Mockups
             return new MqttRpcClient(await ConnectClient(), options);
         }
 
-        public TestApplicationMessageReceivedHandler CreateApplicationMessageHandler(MqttClient mqttClient)
+        public TestApplicationMessageReceivedHandler CreateApplicationMessageHandler(IMqttClient mqttClient)
         {
             return new TestApplicationMessageReceivedHandler(mqttClient);
         }
 
-        public MqttClient CreateClient()
+        public IMqttClient CreateClient()
         {
             lock (_clients)
             {
@@ -228,7 +227,7 @@ namespace MQTTnet.Tests.Mockups
             }
         }
 
-        public LowLevelMqttClient CreateLowLevelClient()
+        public ILowLevelMqttClient CreateLowLevelClient()
         {
             lock (_clients)
             {

Source/MQTTnet.Tests/Server/Session_Tests.cs

@@ -277,7 +277,7 @@ namespace MQTTnet.Tests.Server
             }
         }
 
-        async Task<MqttClient> ConnectAndSubscribe(TestEnvironment testEnvironment, MqttClientOptionsBuilder options, Action onReceive)
+        async Task<IMqttClient> ConnectAndSubscribe(TestEnvironment testEnvironment, MqttClientOptionsBuilder options, Action onReceive)
         {
             try
             {
@@ -302,7 +302,7 @@ namespace MQTTnet.Tests.Server
             }
         }
 
-        async Task<MqttClient> TryConnect(TestEnvironment testEnvironment, MqttClientOptionsBuilder options)
+        async Task<IMqttClient> TryConnect(TestEnvironment testEnvironment, MqttClientOptionsBuilder options)
         {
             try
             {

Source/MQTTnet/Client/IMqttClient.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Diagnostics;
+
+namespace MQTTnet.Client
+{
+    public interface IMqttClient : IDisposable
+    {
+        event Func<MqttClientConnectedEventArgs, Task> ConnectedAsync;
+        
+        event Func<MqttClientConnectingEventArgs, Task> ConnectingAsync;
+        
+        event Func<MqttClientDisconnectedEventArgs, Task> DisconnectedAsync;
+        
+        event Func<MqttApplicationMessageReceivedEventArgs, Task> ApplicationMessageReceivedAsync;
+        
+        event Func<InspectMqttPacketEventArgs, Task> InspectPackage;
+        
+        bool IsConnected { get; }
+        
+        MqttClientOptions Options { get; }
+        
+        Task<MqttClientConnectResult> ConnectAsync(MqttClientOptions options, CancellationToken cancellationToken = default);
+        
+        Task DisconnectAsync(MqttClientDisconnectOptions options, CancellationToken cancellationToken = default);
+        
+        Task PingAsync(CancellationToken cancellationToken = default);
+        
+        Task SendExtendedAuthenticationExchangeDataAsync(MqttExtendedAuthenticationExchangeData data, CancellationToken cancellationToken = default);
+        
+        Task<MqttClientSubscribeResult> SubscribeAsync(MqttClientSubscribeOptions options, CancellationToken cancellationToken = default);
+        
+        Task<MqttClientUnsubscribeResult> UnsubscribeAsync(MqttClientUnsubscribeOptions options, CancellationToken cancellationToken = default);
+        
+        Task<MqttClientPublishResult> PublishAsync(MqttApplicationMessage applicationMessage, CancellationToken cancellationToken = default);
+    }
+}

Source/MQTTnet/Client/MqttClient.cs

@@ -17,7 +17,7 @@ using MQTTnet.Implementations;
 
 namespace MQTTnet.Client
 {
-    public sealed class MqttClient : Disposable
+    public sealed class MqttClient : Disposable, IMqttClient
     {
         readonly MqttPacketFactories _packetFactories = new MqttPacketFactories();
         

Source/MQTTnet/Client/MqttClientExtensions.cs

@@ -14,7 +14,7 @@ namespace MQTTnet.Client
 {
     public static class MqttClientExtensions
     {
-        public static Task DisconnectAsync(this MqttClient client, MqttClientDisconnectReason reason = MqttClientDisconnectReason.NormalDisconnection, string reasonString = null)
+        public static Task DisconnectAsync(this IMqttClient client, MqttClientDisconnectReason reason = MqttClientDisconnectReason.NormalDisconnection, string reasonString = null)
         {
             if (client == null)
             {
@@ -31,7 +31,7 @@ namespace MQTTnet.Client
         }
 
         public static Task<MqttClientPublishResult> PublishBinaryAsync(
-            this MqttClient mqttClient,
+            this IMqttClient mqttClient,
             string topic,
             IEnumerable<byte> payload = null,
             MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce,
@@ -58,7 +58,7 @@ namespace MQTTnet.Client
         }
 
         public static Task<MqttClientPublishResult> PublishStringAsync(
-            this MqttClient mqttClient,
+            this IMqttClient mqttClient,
             string topic,
             string payload = null,
             MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce,
@@ -69,7 +69,7 @@ namespace MQTTnet.Client
             return mqttClient.PublishBinaryAsync(topic, payloadBuffer, qualityOfServiceLevel, retain, cancellationToken);
         }
 
-        public static Task SendExtendedAuthenticationExchangeDataAsync(this MqttClient client, MqttExtendedAuthenticationExchangeData data)
+        public static Task SendExtendedAuthenticationExchangeDataAsync(this IMqttClient client, MqttExtendedAuthenticationExchangeData data)
         {
             if (client == null)
             {
@@ -79,7 +79,7 @@ namespace MQTTnet.Client
             return client.SendExtendedAuthenticationExchangeDataAsync(data, CancellationToken.None);
         }
 
-        public static Task<MqttClientSubscribeResult> SubscribeAsync(this MqttClient mqttClient, MqttTopicFilter topicFilter, CancellationToken cancellationToken = default)
+        public static Task<MqttClientSubscribeResult> SubscribeAsync(this IMqttClient mqttClient, MqttTopicFilter topicFilter, CancellationToken cancellationToken = default)
         {
             if (mqttClient == null)
             {
@@ -91,14 +91,13 @@ namespace MQTTnet.Client
                 throw new ArgumentNullException(nameof(topicFilter));
             }
 
-            var subscribeOptions = new MqttClientSubscribeOptionsBuilder().WithTopicFilter(topicFilter)
+            var subscribeOptions = new MqttClientSubscribeOptionsBuilder().WithTopicFilter(topicFilter).Build();
-                .Build();
 
             return mqttClient.SubscribeAsync(subscribeOptions, cancellationToken);
         }
 
         public static Task<MqttClientSubscribeResult> SubscribeAsync(
-            this MqttClient mqttClient,
+            this IMqttClient mqttClient,
             string topic,
             MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce,
             CancellationToken cancellationToken = default)
@@ -113,13 +112,12 @@ namespace MQTTnet.Client
                 throw new ArgumentNullException(nameof(topic));
             }
 
-            var subscribeOptions = new MqttClientSubscribeOptionsBuilder().WithTopicFilter(topic, qualityOfServiceLevel)
+            var subscribeOptions = new MqttClientSubscribeOptionsBuilder().WithTopicFilter(topic, qualityOfServiceLevel).Build();
-                .Build();
 
             return mqttClient.SubscribeAsync(subscribeOptions, cancellationToken);
         }
 
-        public static Task<MqttClientUnsubscribeResult> UnsubscribeAsync(this MqttClient mqttClient, string topic, CancellationToken cancellationToken = default)
+        public static Task<MqttClientUnsubscribeResult> UnsubscribeAsync(this IMqttClient mqttClient, string topic, CancellationToken cancellationToken = default)
         {
             if (mqttClient == null)
             {
@@ -131,8 +129,7 @@ namespace MQTTnet.Client
                 throw new ArgumentNullException(nameof(topic));
             }
 
-            var unsubscribeOptions = new MqttClientUnsubscribeOptionsBuilder().WithTopicFilter(topic)
+            var unsubscribeOptions = new MqttClientUnsubscribeOptionsBuilder().WithTopicFilter(topic).Build();
-                .Build();
 
             return mqttClient.UnsubscribeAsync(unsubscribeOptions, cancellationToken);
         }

Source/MQTTnet/LowLevelClient/ILowLevelMqttClient.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Client;
+using MQTTnet.Diagnostics;
+using MQTTnet.Packets;
+
+namespace MQTTnet.LowLevelClient
+{
+    public interface ILowLevelMqttClient : IDisposable
+    {
+        event Func<InspectMqttPacketEventArgs, Task> InspectPackage;
+        
+        bool IsConnected { get; }
+        
+        Task ConnectAsync(MqttClientOptions options, CancellationToken cancellationToken = default);
+        
+        Task DisconnectAsync(CancellationToken cancellationToken = default);
+        
+        Task<MqttPacket> ReceiveAsync(CancellationToken cancellationToken = default);
+        
+        Task SendAsync(MqttPacket packet, CancellationToken cancellationToken = default);
+    }
+}

Source/MQTTnet/LowLevelClient/LowLevelMqttClient.cs

@@ -14,7 +14,7 @@ using MQTTnet.Packets;
 
 namespace MQTTnet.LowLevelClient
 {
-    public sealed class LowLevelMqttClient : IDisposable
+    public sealed class LowLevelMqttClient : ILowLevelMqttClient
     {
         readonly IMqttClientAdapterFactory _clientAdapterFactory;
         readonly AsyncEvent<InspectMqttPacketEventArgs> _inspectPacketEvent = new AsyncEvent<InspectMqttPacketEventArgs>();

Source/MQTTnet/MqttFactory.cs

@@ -2,15 +2,15 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using MQTTnet.Adapter;
-using MQTTnet.Client;
-using MQTTnet.Implementations;
-using MQTTnet.LowLevelClient;
-using MQTTnet.Server;
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using MQTTnet.Adapter;
+using MQTTnet.Client;
 using MQTTnet.Diagnostics;
+using MQTTnet.Implementations;
+using MQTTnet.LowLevelClient;
+using MQTTnet.Server;
 using MqttClient = MQTTnet.Client.MqttClient;
 
 namespace MQTTnet
@@ -26,7 +26,7 @@ namespace MQTTnet
         public MqttFactory(IMqttNetLogger logger)
         {
             DefaultLogger = logger ?? throw new ArgumentNullException(nameof(logger));
-            
+
             _clientAdapterFactory = new MqttClientAdapterFactory();
         }
 
@@ -39,62 +39,97 @@ namespace MQTTnet
 
         public IDictionary<object, object> Properties { get; } = new Dictionary<object, object>();
 
-        public MqttFactory UseClientAdapterFactory(IMqttClientAdapterFactory clientAdapterFactory)
+        public MqttApplicationMessageBuilder CreateApplicationMessageBuilder()
         {
-            _clientAdapterFactory = clientAdapterFactory ?? throw new ArgumentNullException(nameof(clientAdapterFactory));
+            return new MqttApplicationMessageBuilder();
-            return this;
         }
 
-        public LowLevelMqttClient CreateLowLevelMqttClient()
+        public MqttClientDisconnectOptionsBuilder CreateClientDisconnectOptionsBuilder()
+        {
+            return new MqttClientDisconnectOptionsBuilder();
+        }
+
+        public MqttClientOptionsBuilder CreateClientOptionsBuilder()
+        {
+            return new MqttClientOptionsBuilder();
+        }
+
+        public ILowLevelMqttClient CreateLowLevelMqttClient()
         {
             return CreateLowLevelMqttClient(DefaultLogger);
         }
 
-        public LowLevelMqttClient CreateLowLevelMqttClient(IMqttNetLogger logger)
+        public ILowLevelMqttClient CreateLowLevelMqttClient(IMqttNetLogger logger)
         {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            if (logger == null)
+            {
+                throw new ArgumentNullException(nameof(logger));
+            }
 
             return new LowLevelMqttClient(_clientAdapterFactory, logger);
         }
 
-        public LowLevelMqttClient CreateLowLevelMqttClient(IMqttClientAdapterFactory clientAdapterFactory)
+        public ILowLevelMqttClient CreateLowLevelMqttClient(IMqttClientAdapterFactory clientAdapterFactory)
         {
-            if (clientAdapterFactory == null) throw new ArgumentNullException(nameof(clientAdapterFactory));
+            if (clientAdapterFactory == null)
+            {
+                throw new ArgumentNullException(nameof(clientAdapterFactory));
+            }
 
             return new LowLevelMqttClient(_clientAdapterFactory, DefaultLogger);
         }
 
-        public LowLevelMqttClient CreateLowLevelMqttClient(IMqttNetLogger logger, IMqttClientAdapterFactory clientAdapterFactory)
+        public ILowLevelMqttClient CreateLowLevelMqttClient(IMqttNetLogger logger, IMqttClientAdapterFactory clientAdapterFactory)
         {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            if (logger == null)
-            if (clientAdapterFactory == null) throw new ArgumentNullException(nameof(clientAdapterFactory));
+            {
+                throw new ArgumentNullException(nameof(logger));
+            }
+
+            if (clientAdapterFactory == null)
+            {
+                throw new ArgumentNullException(nameof(clientAdapterFactory));
+            }
 
             return new LowLevelMqttClient(_clientAdapterFactory, logger);
         }
 
-        public MqttClient CreateMqttClient()
+        public IMqttClient CreateMqttClient()
         {
             return CreateMqttClient(DefaultLogger);
         }
 
-        public MqttClient CreateMqttClient(IMqttNetLogger logger)
+        public IMqttClient CreateMqttClient(IMqttNetLogger logger)
         {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            if (logger == null)
+            {
+                throw new ArgumentNullException(nameof(logger));
+            }
 
             return new MqttClient(_clientAdapterFactory, logger);
         }
 
-        public MqttClient CreateMqttClient(IMqttClientAdapterFactory clientAdapterFactory)
+        public IMqttClient CreateMqttClient(IMqttClientAdapterFactory clientAdapterFactory)
         {
-            if (clientAdapterFactory == null) throw new ArgumentNullException(nameof(clientAdapterFactory));
+            if (clientAdapterFactory == null)
+            {
+                throw new ArgumentNullException(nameof(clientAdapterFactory));
+            }
 
             return new MqttClient(clientAdapterFactory, DefaultLogger);
         }
 
-        public MqttClient CreateMqttClient(IMqttNetLogger logger, IMqttClientAdapterFactory clientAdapterFactory)
+        public IMqttClient CreateMqttClient(IMqttNetLogger logger, IMqttClientAdapterFactory clientAdapterFactory)
         {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            if (logger == null)
-            if (clientAdapterFactory == null) throw new ArgumentNullException(nameof(clientAdapterFactory));
+            {
+                throw new ArgumentNullException(nameof(logger));
+            }
+
+            if (clientAdapterFactory == null)
+            {
+                throw new ArgumentNullException(nameof(clientAdapterFactory));
+            }
 
             return new MqttClient(clientAdapterFactory, logger);
         }
@@ -106,7 +141,10 @@ namespace MQTTnet
 
         public MqttServer CreateMqttServer(MqttServerOptions options, IMqttNetLogger logger)
         {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            if (logger == null)
+            {
+                throw new ArgumentNullException(nameof(logger));
+            }
 
             var serverAdapters = DefaultServerAdapters.Select(a => a.Invoke(this));
             return CreateMqttServer(options, serverAdapters, logger);
@@ -114,52 +152,53 @@ namespace MQTTnet
 
         public MqttServer CreateMqttServer(MqttServerOptions options, IEnumerable<IMqttServerAdapter> serverAdapters, IMqttNetLogger logger)
         {
-            if (serverAdapters == null) throw new ArgumentNullException(nameof(serverAdapters));
+            if (serverAdapters == null)
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            {
+                throw new ArgumentNullException(nameof(serverAdapters));
+            }
+
+            if (logger == null)
+            {
+                throw new ArgumentNullException(nameof(logger));
+            }
 
             return new MqttServer(options, serverAdapters, logger);
         }
 
         public MqttServer CreateMqttServer(MqttServerOptions options, IEnumerable<IMqttServerAdapter> serverAdapters)
         {
-            if (serverAdapters == null) throw new ArgumentNullException(nameof(serverAdapters));
+            if (serverAdapters == null)
+            {
+                throw new ArgumentNullException(nameof(serverAdapters));
+            }
 
             return new MqttServer(options, serverAdapters, DefaultLogger);
         }
-        
+
         public MqttServerOptionsBuilder CreateServerOptionsBuilder()
         {
             return new MqttServerOptionsBuilder();
         }
-       
-        public MqttClientOptionsBuilder CreateClientOptionsBuilder()
-        {
-            return new MqttClientOptionsBuilder();
-        }
 
-        public MqttClientDisconnectOptionsBuilder CreateClientDisconnectOptionsBuilder()
-        {
-            return new MqttClientDisconnectOptionsBuilder();
-        }
-        
         public MqttClientSubscribeOptionsBuilder CreateSubscribeOptionsBuilder()
         {
             return new MqttClientSubscribeOptionsBuilder();
         }
-        
+
-        public MqttClientUnsubscribeOptionsBuilder CreateUnsubscribeOptionsBuilder()
-        {
-            return new MqttClientUnsubscribeOptionsBuilder();
-        }
-        
         public MqttTopicFilterBuilder CreateTopicFilterBuilder()
         {
             return new MqttTopicFilterBuilder();
         }
 
-        public MqttApplicationMessageBuilder CreateApplicationMessageBuilder()
+        public MqttClientUnsubscribeOptionsBuilder CreateUnsubscribeOptionsBuilder()
         {
-            return new MqttApplicationMessageBuilder();
+            return new MqttClientUnsubscribeOptionsBuilder();
+        }
+
+        public MqttFactory UseClientAdapterFactory(IMqttClientAdapterFactory clientAdapterFactory)
+        {
+            _clientAdapterFactory = clientAdapterFactory ?? throw new ArgumentNullException(nameof(clientAdapterFactory));
+            return this;
         }
     }
 }

Source/MQTTnet/Server/Internal/MqttServerKeepAliveMonitor.cs

@@ -96,10 +96,10 @@ namespace MQTTnet.Server
                 // Values described here: [MQTT-3.1.2-24].
                 // If the client sends 5 sec. the server will allow up to 7.5 seconds.
                 // If the client sends 1 sec. the server will allow up to 1.5 seconds.
-                var maxDurationWithoutPacket = connection.KeepAlivePeriod * 1.5D;
+                var maxSecondsWithoutPacket = connection.KeepAlivePeriod * 1.5D;
 
                 var secondsWithoutPackage = (now - connection.Statistics.LastPacketSentTimestamp).TotalSeconds;
-                if (secondsWithoutPackage < maxDurationWithoutPacket)
+                if (secondsWithoutPackage < maxSecondsWithoutPacket)
                 {
                     // A packet was received before the timeout is affected.
                     return;