项城网站制作多少钱,给别人做网站去掉版权,看小视频的浏览器有哪些,中文网站开发和所有的服务器一样#xff0c;KestrelServer最终需要解决的是网络传输的问题。在《KestrelServer详解[2]: 网络连接是如何创建的#xff1f;》#xff0c;我们介绍了KestrelServer如何利用连接接听器的建立网络连接#xff0c;并再次基础上演示了如何直接利用建立的连接接…和所有的服务器一样KestrelServer最终需要解决的是网络传输的问题。在《KestrelServer详解[2]: 网络连接是如何创建的》我们介绍了KestrelServer如何利用连接接听器的建立网络连接并再次基础上演示了如何直接利用建立的连接接收请求和回复响应。本篇更进一步我们根据其总体设计定义了迷你版的KestrelServer让读者看看这个重要的服务器大体是如何实现的。[本文节选《ASP.NET Core 6框架揭秘》第18章]一、ConnectionDelegate二、IConnectionBuilder三、HTTP 1.x/HTTP 2.x V.S. HTTP 3四、MiniKestrelServer一、ConnectionDelegateASP.NET CORE在“应用”层将针对请求的处理抽象成由中间件构建的管道实际上KestrelServer面向“传输”层的连接也采用了这样的设计。当代表连接的ConnectionContext上下文创建出来之后后续的处理将交给由连接中间件构建的管道进行处理。我们可以根据需要注册任意的中间件来处理连接比如可以将并发连结的控制实现在专门的连接中间件中。ASP.NET CORE管道利用RequestDelegate委托来表示请求处理器连接管道同样定义了如下这个ConnectionDelegate委托。public delegate Task ConnectionDelegate(ConnectionContext connection);二、IConnectionBuilderASP.NET CORE管道中的中间件体现为一个FuncRequestDelegate, RequestDelegate委托连接管道的中间件同样可以利用FuncConnectionDelegate, ConnectionDelegate委托来表示。ASP.NET CORE管道中的中间件注册到IApplicationBuilder对象上并利用它将管道构建出来。连接管道依然具有如下这个IConnectionBuilder接口ConnectionBuilder实现了该接口。public interface IConnectionBuilder
{IServiceProvider ApplicationServices { get; }IConnectionBuilder Use(FuncConnectionDelegate, ConnectionDelegate middleware);ConnectionDelegate Build();
}IConnectionBuilder接口还定义了如下三个扩展方法来注册连接中间件。第一个Use方法使用FuncConnectionContext, FuncTask, Task委托来表示中间件。其余两个方法用来注册管道末端的中间件这样的中间件本质上就是一个ConnectionDelegate委托我们可以将其定义成一个派生于ConnectionHandler的类型。public static class ConnectionBuilderExtensions
{public static IConnectionBuilder Use(this IConnectionBuilder connectionBuilder,FuncConnectionContext, FuncTask, Task middleware);public static IConnectionBuilder Run(this IConnectionBuilder connectionBuilder,FuncConnectionContext, Task middleware);public static IConnectionBuilder UseConnectionHandlerTConnectionHandler(this IConnectionBuilder connectionBuilder) where TConnectionHandler : ConnectionHandler;
}public abstract class ConnectionHandler
{public abstract Task OnConnectedAsync(ConnectionContext connection);
}三、HTTP 1.x/HTTP 2.x V.S. HTTP 3KestrelServer针对HTTP 1.X/2和HTTP 3的设计和实现基本上独立的这一点从监听器的定义就可以看出来。就连接管道来说基于HTTP 3的多路复用连接通过MultiplexedConnectionContext表示它也具有“配套”的MultiplexedConnectionDelegate委托和IMultiplexedConnectionBuilder接口。ListenOptions类型同时实现了IConnectionBuilder和IMultiplexedConnectionBuilder接口意味着我们在注册终结点的时候还可以注册任意中间件。public delegate Task MultiplexedConnectionDelegate(MultiplexedConnectionContext connection);public interface IMultiplexedConnectionBuilder
{IServiceProvider ApplicationServices { get; }IMultiplexedConnectionBuilder Use(FuncMultiplexedConnectionDelegate, MultiplexedConnectionDelegate middleware);MultiplexedConnectionDelegate Build();
}public class MultiplexedConnectionBuilder : IMultiplexedConnectionBuilder
{public IServiceProvider ApplicationServices { get; }public IMultiplexedConnectionBuilder Use(FuncMultiplexedConnectionDelegate, MultiplexedConnectionDelegate middleware);public MultiplexedConnectionDelegate Build();
}public class ListenOptions : IConnectionBuilder, IMultiplexedConnectionBuilder四、MiniKestrelServer在了解了KestrelServer的连接管道后我们来简单模拟一下这种服务器类型的实现为此我们定义了一个名为MiniKestrelServer的服务器类型。简单起见MiniKestrelServer只提供针对HTTP 1.1的支持。对于任何一个服务来说它需要将请求交付给一个IHttpApplicationTContext对象进行处理MiniKestrelServer将这项工作实现在如下这个HostedApplicationTContext类型中。public class HostedApplicationTContext : ConnectionHandler where TContext : notnull
{private readonly IHttpApplicationTContext _application;public HostedApplication(IHttpApplicationTContext application) _application application;public override async Task OnConnectedAsync(ConnectionContext connection){var reader connection!.Transport.Input;while (true){var result await reader.ReadAsync();using (var body new MemoryStream()){var (features, request, response) CreateFeatures(result, body);var closeConnection request.Headers.TryGetValue(Connection, out var vallue) vallue Close;reader.AdvanceTo(result.Buffer.End);var context _application.CreateContext(features);Exception? exception null;try{await _application.ProcessRequestAsync(context);await ApplyResponseAsync(connection, response, body);}catch (Exception ex){exception ex;}finally{_application.DisposeContext(context, exception);}if (closeConnection){await connection.DisposeAsync();return;}}if (result.IsCompleted){break;}}static (IFeatureCollection, IHttpRequestFeature, IHttpResponseFeature) CreateFeatures(ReadResult result, Stream body){var handler new HttpParserHandler();var parserHandler new HttpParser(handler);var length (int)result.Buffer.Length;var array ArrayPoolbyte.Shared.Rent(length);try{result.Buffer.CopyTo(array);parserHandler.Execute(new ArraySegmentbyte(array, 0, length));}finally{ArrayPoolbyte.Shared.Return(array);}var bodyFeature new StreamBodyFeature(body);var features new FeatureCollection();var responseFeature new HttpResponseFeature();features.SetIHttpRequestFeature(handler.Request);features.SetIHttpResponseFeature(responseFeature);features.SetIHttpResponseBodyFeature(bodyFeature);return (features, handler.Request, responseFeature);}static async Task ApplyResponseAsync(ConnectionContext connection, IHttpResponseFeature response, Stream body){var builder new StringBuilder();builder.AppendLine($HTTP/1.1 {response.StatusCode} {response.ReasonPhrase});foreach (var kv in response.Headers){builder.AppendLine(${kv.Key}: {kv.Value});}builder.AppendLine($Content-Length: {body.Length});builder.AppendLine();var bytes Encoding.UTF8.GetBytes(builder.ToString());var writer connection.Transport.Output;await writer.WriteAsync(bytes);body.Position 0;await body.CopyToAsync(writer);}}
}HostedApplicationTContext是对一个IHttpApplicationTContext对象的封装。它派生于抽象类ConnectionHandler重写的OnConnectedAsync方法将针对请求的读取和处理置于一个无限循环中。为了将读取的请求转交给IHostedApplicationTContext对象进行处理它需要根据特性集合将TContext上下文创建出来。这里提供的特性集合只包含三种核心的特性一个是描述请求的HttpRequestFeature特性它是利用HttpParser解析请求荷载内容得到的。另一个是描述响应的HttpResponseFeature特性至于提供响应主体的特性由如下所示的StreamBodyFeature对象来表示。这三个特性的创建实现在CreateFeatures方法中。public class StreamBodyFeature : IHttpResponseBodyFeature
{public Stream Stream { get; }public PipeWriter Writer { get; }public StreamBodyFeature(Stream stream){Stream stream;Writer PipeWriter.Create(Stream);}public Task CompleteAsync() Task.CompletedTask;public void DisableBuffering() { }public Task SendFileAsync(string path, long offset, long? count,CancellationToken cancellationToken default) throw new NotImplementedException();public Task StartAsync(CancellationToken cancellationToken default) Task.CompletedTask;
}包含三大特性的集合随后作为参数调用了IHostedApplicationTContext对象的CreateContext方法将TContext上下文创建出来此上下文作为参数传入了同一对象的ProcessRequestAsync方法此时中间件管道接管请求。待中间件管道完成处理后 ApplyResponseAsync方法被调用以完成最终的响应工作。ApplyResponseAsync方法将响应状态从HttpResponseFeature特性中提取并生成首行响应内容“HTTP/1.1 {StatusCode} {ReasonPhrase}”然后再从这个特性中将响应报头提取出来并生成相应的文本。响应报文的首行内容和报头文本按照UTF-8编码生成二进制数组后利用ConnectionContext上下文的Transport属性返回的IDuplexPipe对象发送出去后它再将StreamBodyFeature特性收集到的响应主体输出流“拷贝”到这个IDuplexPipe对象中进而完成了针对响应主体内容的输出。如下所示的是MiniKestrelServer类型的完整定义。该类型的构造函数中注入了用于提供配置选项的IOptionsKestrelServerOptions特性和IConnectionListenerFactory工厂并且创建了一个ServerAddressesFeature对象并注册到Features属性返回的特性集合中。public class MiniKestrelServer : IServer
{private readonly KestrelServerOptions _options;private readonly IConnectionListenerFactory _factory;private readonly ListIConnectionListener _listeners new();public IFeatureCollection Features { get; } new FeatureCollection();public MiniKestrelServer( IOptionsKestrelServerOptions optionsAccessor, IConnectionListenerFactory factory){_factory factory;_options optionsAccessor.Value;Features.SetIServerAddressesFeature( new ServerAddressesFeature());}public void Dispose() StopAsync(CancellationToken.None) .GetAwaiter() .GetResult();public Task StartAsyncTContext( IHttpApplicationTContext application, CancellationToken cancellationToken) where TContext : notnull{var feature Features .GetIServerAddressesFeature()!;IEnumerableListenOptions listenOptions;if (feature.PreferHostingUrls){listenOptions BuildListenOptions(feature);}else{listenOptions _options.GetListenOptions();if (!listenOptions.Any()){listenOptions BuildListenOptions(feature);}}foreach (var options in listenOptions){_ StartAsync(options);}return Task.CompletedTask;async Task StartAsync(ListenOptions litenOptions){var listener await _factory.BindAsync(litenOptions.EndPoint,cancellationToken);_listeners.Add(listener!);var hostedApplication new HostedApplicationTContext(application);var pipeline litenOptions.Use(next context hostedApplication.OnConnectedAsync(context)).Build();while (true){var connection await listener.AcceptAsync();if (connection ! null){_ pipeline(connection);}}}IEnumerableListenOptions BuildListenOptions(IServerAddressesFeature feature){var options new KestrelServerOptions();foreach (var address in feature.Addresses){var url new Uri(address);if (string.Compare(localhost, url.Host, true) 0){options.ListenLocalhost(url.Port);}else{options.Listen(IPAddress.Parse(url.Host), url.Port);}}return options.GetListenOptions();}}public Task StopAsync(CancellationToken cancellationToken) Task.WhenAll(_listeners.Select(it it.DisposeAsync().AsTask()));
}实现的StartAsyncTContext方法先将IServerAddressesFeature特性提取出来并利用其PreferHostingUrls属性决定应该使用直接注册到KestrelOptions配置选项上的终结点还是使用注册在该特定上的监听地址。如果使用后者注册的监听地址会利用BuildListenOptions方法转换成对应的ListenOptions列表否则直接从KestrelOptions对象的ListenOptions属性提取所有的ListenOptions列表由于这是一个内部属性不得不利用如下这个扩展方法以反射的方式获取这个列表。public static class KestrelServerOptionsExtensions
{public static IEnumerableListenOptions GetListenOptions(this KestrelServerOptions options){var property typeof(KestrelServerOptions).GetProperty(ListenOptions,BindingFlags.NonPublic | BindingFlags.Instance);return (IEnumerableListenOptions)property!.GetValue(options)!;}
}对于每一个表示注册终结点的ListenOptions配置选项StartAsyncTContext方法利用IConnectionListenerFactory工厂将对应的IConnectionListener监听器创建出来并绑定到指定的终结点上监听连接请求。表示连接的ConnectionContext上下文一旦被创建出来后该方法便会利用构建的连接管道对它进行处理。在调用ListenOptions配置选项的Build方法构建连接管道前StartAsyncTContext方法将HostedApplicationTContext对象创建出来并作为中间件进行了注册。所以针对连接的处理将被这个HostedApplicationTContext对象接管。using App;
using Microsoft.AspNetCore.Hosting.Server;
using Microsoft.Extensions.DependencyInjection.Extensions;var builder WebApplication.CreateBuilder();
builder.WebHost.UseKestrel(kestrel kestrel.ListenLocalhost(5000));
builder.Services.Replace(ServiceDescriptor.SingletonIServer, MiniKestrelServer());
var app builder.Build();
app.Run(context context.Response.WriteAsync(Hello World!));
app.Run();如上所示的演示程序将替换了针对IServer的服务注册意味着默认的KestrelServer将被替换成自定义的MiniKestrelServer。启动该程序后由浏览器发送的HTTP请求不支持HTTPS同样会被正常处理并得到如图1所示的响应内容。需要强调一下MiniKestrelServer仅仅用来模拟KestrelServer的实现原理不要觉得真实的实现会如此简单。图1 由MiniKestrelServer回复的响应内容
