After several submissions, I have implemented the following refactorings. See also#2101

IMqttBuilder

IMqttBuilder is used to provide common functions for build MqttServer and MqttClient, such as logging.

publicinterfaceIMqttBuilder{IServiceCollectionServices{get;}}

Extensions

publicstaticIMqttBuilderUseMqttNetNullLogger(thisIMqttBuilderbuilder);publicstaticIMqttBuilderUseAspNetCoreMqttNetLogger(thisIMqttBuilderbuilder);publicstaticIMqttBuilderUseLogger<TLogger>(thisIMqttBuilderbuilder)whereTLogger:class,IMqttNetLogger;

IMqttServerBuilder

publicinterfaceIMqttServerBuilder:IMqttBuilder{}

Extensions

publicstaticIMqttServerBuilderAddMqttServer(thisIServiceCollectionservices);publicstaticIMqttServerBuilderConfigureMqttServer(thisIMqttServerBuilderbuilder,Action<MqttServerOptionsBuilder>configure);publicstaticIMqttServerBuilderConfigureMqttServerStop(thisIMqttServerBuilderbuilder,Action<MqttServerStopOptionsBuilder>configure);publicstaticIMqttServerBuilderAddMqttServerAdapter<TMqttServerAdapter>(thisIMqttServerBuilderbuilder);

IMqttClientBuilder

publicinterfaceIMqttClientBuilder:IMqttBuilder{}

Extensions

publicstaticIMqttClientBuilderAddMqttClient(thisIServiceCollectionservices);publicstaticIMqttClientBuilderUseMQTTnetMqttClientAdapterFactory(thisIMqttClientBuilderbuilder);publicstaticIMqttClientBuilderUseAspNetCoreMqttClientAdapterFactory(thisIMqttClientBuilderbuilder);publicstaticIMqttClientBuilderUseMqttClientAdapterFactory<TMqttClientAdapterFactory>(thisIMqttClientBuilderbuilder)whereTMqttClientAdapterFactory:class,IMqttClientAdapterFactory;

New implementation of IMqttClientAdapterFactory

The SocketConnection that the original MqttClientConnectionContextFactory depends on is a copy of the early code of the kestrel project. It is now deleted and replaced bythe IConnectionFactory service of Asp.NetCore to create ConnectionContext instead of SocketConnection ClientConnectionContext, which is a wrapper class for Stream and now supports TCP, TLS, WS and WSS. See also#2104#2105

IConnectionFactory only provides an asynchronous ConnectAsync() method. In order to call this asynchronous method, we need to modify the CreateClientAdapter method of IMqttClientAdapterFactory toValueTask<IMqttChannelAdapter> CreateClientAdapterAsync().

Now, the implementation type of IMqttClientAdapterFactory is AspNetCoreMqttClientAdapterFactory, which is an internal modified type and is used by users through IMqttClientBuilder.UseAspNetCoreMqttClientAdapterFactory().

The dependency chain is IMqttClientAdapterFactory-->AspNetCoreMqttClientAdapterFactory-->MqttClientChannelAdapter-->MqttChannel-->ClientConnectionContext

Split MqttHostedServer

MqttHostedServer acts as both MqttServer and HostedService, which makes it difficult to register the service and start the service background.

It has now been split into AspNetCoreMqttServer and AspNetCoreMqttHostedServer. AspNetCoreMqttHostedServer inherits BackgroundService. In its ExecuteAsync method, it waits for the application to start and then starts AspNetCoreMqttServer.#2102

Split MqttConnectionHandler

MqttConnectionHandler no longer implements the IMqttServerAdapter interface. The implementation type of IMqttServerAdapter is AspNetCoreMqttServerAdapter.

The dependency chain is IMqttServerAdapter-->AspNetCoreMqttServerAdapter-->MqttConnectionHandler-->MqttServerChannelAdapter-->MqttChannel-->Kestrel ConnectionContext

Add MqttBufferWriterPool in server mode

MqttBufferWriterPool pools the MqttBufferWriters of channels whose lifecycles are less than one minute to reduce the number of MqttBufferWriters created when clients frequently connect and disconnect.

Add MqttConnectionMiddleware

MqttConnectionMiddleware allows a single port to support both mqtt and mqtt-overt-websocket protocols. It is ultimately applied by IConnectionBuilder.UseMqtt(MqttProtocols).

Add KestrelServerOptions.ListenMqtt(MqttProtocols) extensions

This extension perfectly adapts the listening options of MqttServerOptions to kestrel, allowing users to continue to use the familiar MqttServerOptionsBuilder. In addition, we also provide enhanced httpsOptions configuration.

Make all implementation types internal

Now all implementation types have been modified to internal, and use InternalsVisibleToAttribute to expose them to the specified assembly.

Logger

The new AspNetCoreMqttNetLogger type is now the default IMqttNetLogger, which writes log content to Microsoft.Extensions.Logging.

Nullable

Nullable feature is enabled.

UnitTest

The newAspNetCoreTestEnvironment is added to the test environment and participates in the test at the same time as the defaultTestEnvironment.

Exception

Now the exception types and exception behaviors of MqttChannel are exactly the same as those of MqttChannelAdapter.