IIS 7.0 Architecture

IIS 7.0 ArchitectureInclude the following components
1. HTTP.Sys
2. World Wide Web Publishing Service
3. Windows Process Activation Services(WAS)

HTTP.SysIs part of networking subsystem of Windows operating systems, and is implemented as a kernel mode device driver called the HTTP protocol stack(HTTP.sys). HTTP.sys listens for HTTP requests from the network, passes the requests onto IIS for processing, and then returns processed responses to client browsers.

WWS :No longer manages worker process. Instead WWS is listener adapter for HTTP.sys.
Is primarily responsible for configuring HTTP.sys,updating HTTP.sys when configuration changes, and notifying WAS when a request enters the request queue.

WAS:
Manages application pool configuration and worker processed instead of WWS

Reference:
http://learn.iis.net/page.aspx/101/introduction-to-iis-7-architecture/