The ASP.NET MVC request processing line

Stage 1:IISCan enable ASP.NET in one of two managed pipelinemodes:

　　a. In ISAPI mode, also called Classic mode, ASP.NET is invoked through an ISAPI extension (aspnet_isapi.dll), associated with particular URL "file name extensions"(e.g., .aspx, .ashx, .mvc). You'll learn more about deployingMVC Framework applicaitons to IIS6, including setting upwildcard maps, in Chapter 14.
PS:Internet Services API(ISAPI) is IIS's old plug-in system. You can only create ISAPI extensions in unmanaged (e.g. C/c++) code.
　　b.In Integrated mode( only supported by IIS 7+), .NET is a native part of the IIS request processing pipeline,so you don't need an ISAPI extension associated with a particular URL file name extension. That makes it easy to userouting configurations with perfectly clean URLs(i.e.,with no file name extension).

Stage 2: Core Routing

Stage 3: Controllers and Actions

Stage 4: Action Results and Views