Request---------------->IIS(w3wp.exe)--------------->CLR(AppDomain)-------------------->ASP.NET(HttpRuntime)---------------->WebSite(HttpApplication)/HttpContext

HTTP.SYS  (Kernel Layer) --> WAS (Web Admin Services) (User Layer) --> Application Pool --> Worker Process (w3wp.exe) --> ISAPI Process (aspnet_isapi.dll) -->  HTTPRuntime Process

http://msdn.microsoft.com/en-us/library/07yaywa9(v=vs.71).aspx

http://dotnetslackers.com/articles/iis/ASPNETInternalsIISAndTheProcessModel.aspx

http://www.west-wind.com/presentations/howaspnetworks/howaspnetworks.asp

http://odetocode.com/Articles/89.aspx

http://www.codeproject.com/Articles/42724/Beginner-s-Guide-Exploring-IIS-6-0-With-ASP-NET

http://support.microsoft.com/kb/815162

http://jasper-net.blogspot.com/2012/04/how-iis-processes-aspnet-request.html

http://technet.microsoft.com/en-us/library/cc783576(v=WS.10).aspx