Owin管道与asp.net管道模型

------2016.3.6 更新 文中提到没有Microsoft.Owin.Host.SystemWeb 这个dll 便不会加载Startup.Configuration，因为这个dll 其中有个OwinHttpModul. 网站回加载这个modul然后在这里面实现了owin的管道（ps 就是 把owin定义的模块挂载到httpapplication的 几个事件上）。

最近一直没搞懂在 mvc5框架中 为什么存在 Global.asax.cs和Startup.cs 文件... 

然后搜索下面文章：

http://stackoverflow.com/questions/20168978/do-i-need-a-global-asax-cs-file-at-all-if-im-using-an-owin-startup-cs-class-and

其中提到 

1、Application_Start 会比Startup.Configuration 先启动 

2、mvc4 版本一致性 布啦布啦....

3、 Global.asax.cs 可以处理一些特殊事件 例如 Application_Start Application_Error Session_Start 等等

4、Startup.Configuration 中可以配置 关于授权之类的(替代原先的Application_AuthenticateRequest，另外mvc5中引入了ASP.NET Identity 2,而这个基于Owin)

5、最最重要的一条如果 引用集没有Microsoft.Owin.Host.SystemWeb 这个dll 便不会加载Startup.Configuration

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ok 进入另一个话题 owin 的管道有什么 首先贴下微软的PipelineStage

namespace Owin
{
  /// <summary>
  /// An ordered list of known Asp.Net integrated pipeline stages. More details on the ASP.NET integrated pipeline can be found at http://msdn.microsoft.com/en-us/library/system.web.httpapplication.aspx
  /// 
  /// </summary>
  public enum PipelineStage
  {
    Authenticate,
    PostAuthenticate,
    Authorize,
    PostAuthorize,
    ResolveCache,
    PostResolveCache,
    MapHandler,
    PostMapHandler,
    AcquireState,
    PostAcquireState,
    PreHandlerExecute,
  }
}

看注释 去看 httpapplication事件。。。个人感觉Owin管道里的事件是可以替代原先的httpapplication事件的。。。

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既然说到Startup.Configuration可以替代 那怎么用才是关键，直接上代码：

public void Configuration(IAppBuilder app)
{
    app.Use((context, next) =>
    {
        PrintCurrentIntegratedPipelineStage(context, "Middleware 1");
        return next.Invoke();
    });
    app.Use((context, next) =>
    {
        PrintCurrentIntegratedPipelineStage(context, "2nd MW");
        return next.Invoke();
    });
    app.UseStageMarker(PipelineStage.Authenticate);
    app.Run(context =>
    {
        PrintCurrentIntegratedPipelineStage(context, "3rd MW");
        return context.Response.WriteAsync("Hello world");
    });
    app.UseStageMarker(PipelineStage.ResolveCache);
}

看代码中红色部分。。。 使用app.UseStageMarker(xxxx状态)之前的代码 便是xxxx状态注册。

注意：

　　1、如果不是用UseStageMarker标记 那些中间件的位置 所有的位置为：PreHandlerExecute。

　　2、多次使用UseStageMarker 不能 前面顺序比后面大。。。

      相关链接：http://www.asp.net/aspnet/overview/owin-and-katana/owin-middleware-in-the-iis-integrated-pipeline

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个人一些闲言碎语

貌似 asp.net5 里 mvc框架 中没有了Global.asax.cs文件 入口就是Startup.cs 

还有 个人感觉  IOwinConent 会替代 HttpAplication ；OwinMiddleware 替代IHttpModule ( 当然这是指 asp.net5里，而mvc5中还是 混搭风格),app.Use(xxxxxx)构成的 管道还是 相对好理解的 

不过现在asp.net 还是 rc等出了 rtm再来更新吧。。。。

 贴下 asp.net5中Startup

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNet.Builder;
using Microsoft.AspNet.Hosting;
using Microsoft.AspNet.Identity.EntityFramework;
using Microsoft.Data.Entity;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using WebApplication2.Models;
using WebApplication2.Services;

namespace WebApplication2
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            // Set up configuration sources.
            var builder = new ConfigurationBuilder()
                .AddJsonFile("appsettings.json")
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);

            if (env.IsDevelopment())
            {
                // For more details on using the user secret store see http://go.microsoft.com/fwlink/?LinkID=532709
                builder.AddUserSecrets();
            }

            builder.AddEnvironmentVariables();
            Configuration = builder.Build();
        }

        public IConfigurationRoot Configuration { get; set; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.
            services.AddEntityFramework()
                .AddSqlServer()
                .AddDbContext<ApplicationDbContext>(options =>
                    options.UseSqlServer(Configuration["Data:DefaultConnection:ConnectionString"]));

            services.AddIdentity<ApplicationUser, IdentityRole>()
                .AddEntityFrameworkStores<ApplicationDbContext>()
                .AddDefaultTokenProviders();

            services.AddMvc();

            // Add application services.
            services.AddTransient<IEmailSender, AuthMessageSender>();
            services.AddTransient<ISmsSender, AuthMessageSender>();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            if (env.IsDevelopment())
            {
                app.UseBrowserLink();
                app.UseDeveloperExceptionPage();
                app.UseDatabaseErrorPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");

                // For more details on creating database during deployment see http://go.microsoft.com/fwlink/?LinkID=615859
                try
                {
                    using (var serviceScope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>()
                        .CreateScope())
                    {
                        serviceScope.ServiceProvider.GetService<ApplicationDbContext>()
                             .Database.Migrate();
                    }
                }
                catch { }
            }

            app.UseIISPlatformHandler(options => options.AuthenticationDescriptions.Clear());

            app.UseStaticFiles();

            app.UseIdentity();

            // To configure external authentication please see http://go.microsoft.com/fwlink/?LinkID=532715

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }

        // Entry point for the application.
        public static void Main(string[] args) => WebApplication.Run<Startup>(args);
    }
}