NET pluggable
architecture, handing off the request to the ASP.NET worker process, aspnet_wp.exe.
86 CHAPTER 3 ?– ASP.NET S TATE MANAGEMENT
Figure 3-1. ASP.NET request data flow
The worker process implements the HttpRuntime object, which handles ASP.NET requests
within the same process space and achieves isolation using separate AppDomains. The HttpRuntime
object uses an HttpApplicationFactory object to locate the correct AppDomain and create an
HttpApplication object to process the request. The global.asax file can be used to subscribe
to events available via the HttpApplication object. User state information for the current
user session within the application is made available through the Context property of the
HttpApplication-derived object. We cover Context in more detail in the ???ASP.NET and Server-
Side State Management??? section. At this point in the processing pipeline, any objects that implement
the HttpModule class and are registered in the application will have their events fired.
For example, Session_Start and Session_End are implemented in an HTTP module named
SessionStateModule. HttpModule objects can be used to implement a variety of sitewide functionality,
such as a custom authentication architecture that verifies requests based on custom
HTTP header information.
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