namespace SingalRSample
{
 public partial class Startup
 {
  public void Configuration(IAppBuilder app)
  {
   
  }
 }
}
有兩種方法能讓 SystemWeb 辨識出 Startup
1.定義 OwinStartupAttribute,
例如 [assembly: OwinStartupAttribute(typeof(SingalRSample.ABC.Startup))]
2.按照他說的需要將 Startup 放在 SingalRSample 命名空間下
所以透過 OwinStartupAttribute,也可以自由定義類別名稱,只要也有 Configuration 方法就行,不一定要叫做 Startup 的,
但個人覺得按照習慣來配置會比較好,所以我還是會使用 Startup 在預設的專案命名空間下,這樣讓不同人看到專案時,也好理解。
以下是較完整的 Startup 類別 Sample code #1: (ProjectName\Startup.cs)
using System;
using System.Web.Http;
using Microsoft.Owin;
using Microsoft.Owin.Security.OAuth;
using Owin;
namespace TokenWithoutIdentity {
    public class Startup {
        public void Configuration(IAppBuilder app) {
            HttpConfiguration config = new HttpConfiguration();
            ConfigureOAuth(app);
            WebApiConfig.Register(config);
            app.UseWebApi(config);
        }
        public void ConfigureOAuth(IAppBuilder app) {
            OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions() {
                AllowInsecureHttp = true,
                TokenEndpointPath = new PathString("/token"), //這是要認證token的url
                AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),  //到期日多久,此範例為一天
                Provider = new OAuthAuthorizationServerProvider()  //實作此provider
            };
            // Token Generation
            app.UseOAuthAuthorizationServer(OAuthServerOptions);
            app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());
        }
    }
}
Sample code #2:
using Owin; 
using System.Web.Http; 
namespace OwinSelfhostSample 
{ 
    public class Startup 
    { 
        // This code configures Web API. The Startup class is specified as a type
        // parameter in the WebApp.Start method.
        public void Configuration(IAppBuilder appBuilder) 
        { 
            // Configure Web API for self-host. 
            HttpConfiguration config = new HttpConfiguration(); 
            config.Routes.MapHttpRoute( 
                name: "DefaultApi", 
                routeTemplate: "api/{controller}/{id}", 
                defaults: new { id = RouteParameter.Optional } 
            ); 
            appBuilder.UseWebApi(config); 
        } 
    } 
}