ASP.net request lifecycle
IIS gets the request Looks up a script map extension and maps to aspnet_isapi.dll Code hits the worker process (aspnet_wp.exe in IIS5 or w3wp.exe in IIS6) .NET runtime is loaded IsapiRuntime.ProcessRequest () called by non-managed code IsapiWorkerRequest created once per request HttpRuntime.ProcessRequest () called with Worker Request HttpContext Object created by passing Worker Request as input HttpApplication.GetApplicationInstance () called with Context to retrieve instance from pool HttpApplication.Init () called to start pipeline event sequence and hook up modules and handlers HttpApplicaton.ProcessRequest called to start processing Pipeline events fire Handlers are called and ProcessRequest method are fired Control returns to pipeline and post request events fire Source: ( http://www.west-wind.com/presentations/howaspnetworks/howaspnetworks.asp )