c# - 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 作为依赖项注入(inject)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，我收到一个 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，这也没有用。

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。您必须实现 CaSTLe.MicroKernel.Lifestyle.Scoped.IScopeAccessor 接口(interface)。

然后在注册组件时指定作用域访问器:

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(delegate)给 GetScope 并将 Dispose 委托(delegate)给 PerWebRequestLifestyleOwinMiddleware。

PerWebRequestLifestyleOwinMiddleware 类是 CaSTLe Windsor 的 ASP.NET IHttpModule 的 OWIN 对应部分 PerWebRequestLifestyleModule .

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 利用 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 的想法.

下面OwinRequestScopeContext的实现是我对Yoshifumi Kawai原版OwinRequestScopeContext的轻量级实现。

---

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

PM> 安装包 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); 之前执行此操作:

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。