Datasheet

IIS Request Handling
The initial processing of an HTTP request on Windows Server 2003 occurs within both IIS and a support-
ing protocol driver. As a result, depending on the configuration for IIS, a request may never make it far
enough to be processed by ASP.NET. The diagram in Figure 1-1 shows the salient portions of IIS and
Windows Server 2003 that participate in request processing.
Figure 1-1
A request must first make it past the restrictions enforced by the kernel mode HTTP driver: http.sys. The
request is handed off to a worker process where it then flows through a combination of the internal
request processing provided by IIS and several ISAPI filters and extensions. Ultimately, the request is
routed to the appropriate content handler, which for ASP.NET pages is the ASP.NET runtime’s ISAPI
extension.
static content aspnet_isapi.dll
Worker process
w3wp.exe
aspnet_filter.dll
ISAPI filters
http.sys
Request for
default.aspx
asp.dll
2
Chapter 1
04_596985 ch01.qxp 12/14/05 7:46 PM Page 2