如何在 OWIN 中使用 Castle Windsor 的 PerWebRequest 生活方式

Question

我正在将现有的 ASP .Net Web API 2 项目转换为使用 OWIN。该项目使用 Castle Windsor 作为依赖注入框架，其中一个依赖项设置为使用 PerWebRequest 生活方式。

当我向服务器发出请求时，我得到一个Castle.MicroKernel.ComponentResolutionException 异常。异常建议将以下内容添加到配置文件中的system.web/httpModules 和system.WebServer/modules 部分：

<add name="PerRequestLifestyle"
     type="Castle.MicroKernel.Lifestyle.PerWebRequestLifestyleModule, Castle.Windsor" />

这并不能解决错误。

从 SimpleInjector 的 OWIN 集成提供的示例中获得灵感，我尝试使用以下方法在 OWIN 启动类中设置范围（以及更新依赖项的生活方式）：

appBuilder.User(async (context, next) =>
{
    using (config.DependencyResolver.BeginScope()){
    {
        await next();
    }
}

不幸的是，这也没有奏效。

如何使用 Castle Windsor 的 PerWebRequest 生活方式或在 OWIN 中模拟它？

Answer 1

根据 Castle Windsor 文档，您可以实现自己的自定义范围。你必须实现Castle.MicroKernel.Lifestyle.Scoped.IScopeAccessor 接口。

然后在注册组件时指定范围访问器：

Container.Register(Component.For<MyScopedComponent>().LifestyleScoped<OwinWebRequestScopeAccessor >());

OwinWebRequestScopeAccessor 类实现了 Castle.Windsor 的 IScopeAccessor：

using Castle.MicroKernel.Context;
using Castle.MicroKernel.Lifestyle.Scoped;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace Web.Api.Host
{
    public class OwinWebRequestScopeAccessor : IScopeAccessor
    {
        public void Dispose()
        {
            var scope = PerWebRequestLifestyleOwinMiddleware.YieldScope();
            if (scope != null)
            {
                scope.Dispose();
            }
        }

        public ILifetimeScope GetScope(CreationContext context)
        {
            return PerWebRequestLifestyleOwinMiddleware.GetScope();
        }
    }
}

如您所见，OwinWebRequestScopeAccessor 将调用委托给 GetScope 和 Dispose 给PerWebRequestLifestyleOwinMiddleware。

PerWebRequestLifestyleOwinMiddleware 类是 Castle Windsor 的 ASP.NET IHttpModule PerWebRequestLifestyleModule 的 OWIN 计数器部分。

这是PerWebRequestLifestyleOwinMiddleware 类：

using Castle.MicroKernel;
using Castle.MicroKernel.Lifestyle.Scoped;
using Owin;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Web.Api.Host
{
    using AppFunc = Func<System.Collections.Generic.IDictionary<string, object>, System.Threading.Tasks.Task>;

    public class PerWebRequestLifestyleOwinMiddleware
    {
        private readonly AppFunc _next;
        private const string c_key = "castle.per-web-request-lifestyle-cache";
        private static bool _initialized;

        public PerWebRequestLifestyleOwinMiddleware(AppFunc next)
        {
            _next = next;
        }

        public async Task Invoke(IDictionary<string, object> environment)
        {
            var requestContext = OwinRequestScopeContext.Current;
            _initialized = true;

            try
            {
                await _next(environment);
            }
            finally
            {
                var scope = GetScope(requestContext, createIfNotPresent: false);
                if (scope != null)
                {
                    scope.Dispose();
                }
                requestContext.EndRequest();
            }
        }

        internal static ILifetimeScope GetScope()
        {
            EnsureInitialized();
            var context = OwinRequestScopeContext.Current;
            if (context == null)
            {
                throw new InvalidOperationException(typeof(OwinRequestScopeContext).FullName +".Current is null. " +
                    typeof(PerWebRequestLifestyleOwinMiddleware).FullName +" can only be used with OWIN.");
            }
            return GetScope(context, createIfNotPresent: true);
        }

        /// <summary>
        /// Returns current request's scope and detaches it from the request 
        /// context. Does not throw if scope or context not present. To be 
        /// used for disposing of the context.
        /// </summary>
        /// <returns></returns>
        internal static ILifetimeScope YieldScope()
        {
            var context = OwinRequestScopeContext.Current;
            if (context == null)
            {
                return null;
            }
            var scope = GetScope(context, createIfNotPresent: false);
            if (scope != null)
            {
                context.Items.Remove(c_key);
            }
            return scope;
        }

        private static void EnsureInitialized()
        {
            if (_initialized)
            {
                return;
            }
            throw new ComponentResolutionException("Looks like you forgot to register the OWIN middleware " + typeof(PerWebRequestLifestyleOwinMiddleware).FullName);
        }

        private static ILifetimeScope GetScope(IOwinRequestScopeContext context, bool createIfNotPresent)
        {
            ILifetimeScope candidates = null;
            if (context.Items.ContainsKey(c_key))
            {
                candidates = (ILifetimeScope)context.Items[c_key];
            }
            else if (createIfNotPresent)
            {
                candidates = new DefaultLifetimeScope(new ScopeCache());
                context.Items[c_key] = candidates;
            }
            return candidates;
        }
    }

    public static class AppBuilderPerWebRequestLifestyleOwinMiddlewareExtensions
    {
        /// <summary>
        /// Use <see cref="PerWebRequestLifestyleOwinMiddleware"/>.
        /// </summary>
        /// <param name="app">Owin app.</param>
        /// <returns></returns>
        public static IAppBuilder UsePerWebRequestLifestyleOwinMiddleware(this IAppBuilder app)
        {
            return app.Use(typeof(PerWebRequestLifestyleOwinMiddleware));
        }
    }
}

Castle Windsor 的 ASP.NET IHttpModule PerWebRequestLifestyleModule 使用 HttpContext.Current 在每个 web 请求的基础上存储 Castle Windsor ILifetimeScope。 PerWebRequestLifestyleOwinMiddleware 类使用 OwinRequestScopeContext.Current。这是基于Yoshifumi Kawai的思想。

下面OwinRequestScopeContext的实现是我对川井佳文原创OwinRequestScopeContext的轻量级实现。

---

注意：如果您不想要这种轻量级实现，您可以通过在 NuGet 包管理器控制台中运行以下命令来使用 Yoshifumi Kawai 的优秀原始实现：

PM> Install-Package OwinRequestScopeContext

---

OwinRequestScopeContext的轻量级实现：

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Remoting.Messaging;
using System.Text;
using System.Threading.Tasks;

namespace Web.Api.Host
{
    public interface IOwinRequestScopeContext
    {
        IDictionary<string, object> Items { get; }
        DateTime Timestamp { get; }
        void EndRequest();
    }

    public class OwinRequestScopeContext : IOwinRequestScopeContext
    {
        const string c_callContextKey = "owin.reqscopecontext";
        private readonly DateTime _utcTimestamp = DateTime.UtcNow;
        private ConcurrentDictionary<string, object> _items = new ConcurrentDictionary<string, object>();

        /// <summary>
        /// Gets or sets the <see cref="IOwinRequestScopeContext"/> object 
        /// for the current HTTP request.
        /// </summary>
        public static IOwinRequestScopeContext Current
        {
            get
            {
                var requestContext = CallContext.LogicalGetData(c_callContextKey) as IOwinRequestScopeContext;
                if (requestContext == null)
                {
                    requestContext = new OwinRequestScopeContext();
                    CallContext.LogicalSetData(c_callContextKey, requestContext);
                }
                return requestContext;
            }
            set
            {
                CallContext.LogicalSetData(c_callContextKey, value);
            }
        }

        public void EndRequest()
        {
            CallContext.FreeNamedDataSlot(c_callContextKey);
        }

        public IDictionary<string, object> Items
        {
            get
            {
                return _items;
            }
        }

        public DateTime Timestamp
        {
            get
            {
                return _utcTimestamp.ToLocalTime();
            }
        }
    }
}

当你把所有的部分都准备好后，你就可以把它们绑起来了。在您的 OWIN 启动类中调用 appBuilder.UsePerWebRequestLifestyleOwinMiddleware(); 扩展方法来注册上面定义的 OWIN 中间件。在appBuilder.UseWebApi(config);之前这样做：

using Owin;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Web.Http;
using System.Diagnostics;
using Castle.Windsor;
using System.Web.Http.Dispatcher;
using System.Web.Http.Tracing;

namespace Web.Api.Host
{
    class Startup
    {
        private readonly IWindsorContainer _container;

        public Startup()
        {
            _container = new WindsorContainer().Install(new WindsorInstaller());
        }

        public void Configuration(IAppBuilder appBuilder)
        {
            var properties = new Microsoft.Owin.BuilderProperties.AppProperties(appBuilder.Properties);
            var token = properties.OnAppDisposing;
            if (token != System.Threading.CancellationToken.None)
            {
                token.Register(Close);
            }

            appBuilder.UsePerWebRequestLifestyleOwinMiddleware();

            //
            // Configure Web API for self-host. 
            //
            HttpConfiguration config = new HttpConfiguration();
            WebApiConfig.Register(config);
            appBuilder.UseWebApi(config);
        }

        public void Close()
        {
            if (_container != null)
                _container.Dispose();
        }
    }
}

示例 WindsorInstaller 类展示了如何使用 OWIN per-web-request 范围：

using Castle.MicroKernel.Registration;
using Castle.MicroKernel.SubSystems.Configuration;
using Castle.Windsor;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Web.Api.Host
{
    class WindsorInstaller : IWindsorInstaller
    {
        public void Install(IWindsorContainer container, IConfigurationStore store)
        {
            container.Register(Component
                .For<IPerWebRequestDependency>()
                .ImplementedBy<PerWebRequestDependency>()
                .LifestyleScoped<OwinWebRequestScopeAccessor>());

            container.Register(Component
                .For<Controllers.V1.TestController>()
                .LifeStyle.Transient);
        }
    }
}

我上面列出的解决方案是基于现有的/src/Castle.Windsor/MicroKernel/Lifestyle/PerWebRequestLifestyleModule.cs和Yoshifumi Kawai的原始OwinRequestScopeContext。

Answer 2

我尝试实现 Johan Boonstra's answer，但在我们使用 ASP.NET MVC 控制器方法后发现它不起作用。

这是一个更简单的解决方案：

首先，创建一些位于管道开头的 Owin 中间件并创建一个 DefaultLifetimeScope

public class WebRequestLifestyleMiddleware : OwinMiddleware
{
    public const string EnvironmentKey = "WindsorOwinScope";

    public WebRequestLifestyleMiddleware(OwinMiddleware next) : base(next)
    {
    }

    public override async Task Invoke(IOwinContext context)
    {
        ILifetimeScope lifetimeScope = new DefaultLifetimeScope();
        context.Environment[EnvironmentKey] = lifetimeScope;
        try
        {
            await this.Next.Invoke(context);
        }
        finally
        {
            context.Environment.Remove(EnvironmentKey);
            lifetimeScope.Dispose();
        }
    }
}

将它插入到启动配置中管道的开头：

public void Configure(IAppBuilder appBuilder)
{
    appBuilder.Use<WebRequestLifestyleMiddleware>();

    //
    // Further configuration
    //
}

现在您创建一个实现IScopeAccessor 并获取WebRequestLifestyleMiddleware 推入环境的范围的类：

public class OwinWebRequestScopeAccessor : IScopeAccessor
{
    void IDisposable.Dispose() { }

    ILifetimeScope IScopeAccessor.GetScope(CreationContext context)
    {
        IOwinContext owinContext = HttpContext.Current.GetOwinContext();
        string key = WebRequestLifestyleMiddleware.EnvironmentKey;
        return owinContext.Environment[key] as ILifetimeScope;
    }
}

最后，在注册组件生命周期时使用这个范围访问器。例如，我有一个名为 AccessCodeProvider 的自定义组件，我想在一个请求中重用它：

container.Register(
      Component.For<AccessCodeProvider>()
               .LifestyleScoped<OwinRequestScopeAccessor>()
);

在这种情况下，AccessCodeProvider 将在第一次在请求中被请求时创建，然后在整个网络请求中重复使用，最后在 WebRequestLifestyleMiddleware 调用 lifetimeScope.Dispose() 时被处理。

Answer 3

我在一个 web api 应用程序中创建了 PerScope 生活方式，其行为类似于 PerWebRequest，该应用程序使用 owin 中间件和城堡温莎作为应用程序的 IoC。

首先让我们将 windsor 容器作为 web api 应用程序的 IoC，如下所示：

    public class WindsorHttpDependencyResolver : IDependencyResolver
    {
        private readonly IWindsorContainer container;

        public WindsorHttpDependencyResolver(IWindsorContainer container)
        {
            if (container == null)
            {
                throw new ArgumentNullException("container");
            }
            this.container = container;
        }

        public object GetService(Type t)
        {
            return this.container.Kernel.HasComponent(t)
             ? this.container.Resolve(t) : null;
        }

        public IEnumerable<object> GetServices(Type t)
        {
            return this.container.ResolveAll(t).Cast<object>().ToArray();
        }

        public IDependencyScope BeginScope()
        {
            return new WindsorDependencyScope(this.container);
        }

        public void Dispose()
        {
        }
    }//end WindsorHttpDependencyResolver 

  public class WindsorDependencyScope : IDependencyScope
    {
        private readonly IWindsorContainer container;
        private readonly IDisposable scope;

        public WindsorDependencyScope(IWindsorContainer container)
        {
            if (container == null)
                throw new ArgumentNullException("container");

            this.container = container;
        }

        public object GetService(Type t)
        {
            return this.container.Kernel.HasComponent(t)
                ? this.container.Resolve(t) : null;
        }

        public IEnumerable<object> GetServices(Type t)
        {
            return this.container.ResolveAll(t).Cast<object>().ToArray();
        }

        public void Dispose()
        {
            this.scope?.Dispose();
        }
    }

然后在应用程序启动时注册它：

container.Register(Component.For<System.Web.Http.Dependencies.IDependencyResolver>().ImplementedBy<WindsorHttpDependencyResolver>().LifestyleSingleton());

现在在第一个中间件中（这将是第一个和最后一个中间件将被执行）让我们在新请求到达我们的 web api 时开始作用域，并在它结束时将其处理如下：

public class StartinMiddleware : OwinMiddleware
{

    public StartinMiddleware(OwinMiddleware next) : base(next)
    {
        if (next == null)
        {
            throw new ArgumentNullException("next");
        }
    }


    public override async Task Invoke(IOwinContext context)
    {

        this.Log().Info("Begin request");
        IDisposable scope = null;            
        try
        {
            // here we are using IoCResolverFactory which returns 
            // the instance of IoC container(which will be singleton for the 
            // whole application)
            var ioCResolver= IoCResolverFactory.GetOrCreate();
            //here we are starting new scope
            scope = ioCResolver.BeginScope();

            await Next.Invoke(context);

            this.Log().Info("End request");
        }
        catch (Exception ex)
        { 
          //here you can log exceptions
        }
        finally
        {
            //here we are desposing scope
            scope?.Dispose();
        }
    }
}

IoC 工厂的代码是这样的：

public static class IoCResolverFactory
{
    public static IoCResolver iocResolver;

    public static IoCResolver GetOrCreate()
    {
        if (iocResolver != null)
            return iocResolver;

        iocResolver = new IoCResolver();
        return iocResolver;
    }
}// end IoCResolverFactory

public class IoCResolver
{
    private static WindsorContainer container;

    public IoCResolver()
    {
        container = new WindsorContainer();

        container.Register(Component.For<IoCResolver>().Instance(this).LifestyleSingleton());
        container.Register(Component.For<IWindsorContainer>().Instance(container).LifestyleSingleton());
    }


    public IDisposable BeginScope()
    {
        return container.BeginScope();
    }


    public IDisposable GetCurrentScope()
    {
        return Castle.MicroKernel.Lifestyle.Scoped.CallContextLifetimeScope.ObtainCurrentScope();
    }


    public T Resolve<T>()
    {
        return container.Resolve<T>();
    }

    public IList<T> ResolveAll<T>()
    {
        return container.ResolveAll<T>();
    }

    public void Dispose()
    {
        container.Dispose();
    }
}

在启动期间注册服务时，您可以将它们注册为按范围解析，如下所示：

container.Register(Component.For<ICurrentRequestService>().ImplementedBy<CurrentRequestService>().LifestyleScoped());