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

----------------------分割线----------------------------------

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。。。

--------------------------------------------分割线-----------------------------------------------------

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

----------------------------分割线-----------------------------------------------------------

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);
     }
 }