Programming Microsoft ASP.NET 3.5

ASP.NET pages are dynamically compiled on demand when first required in the context of
a Web application. Dynamic compilation is not specific to ASP.NET pages (.aspx files); it also
occurs with .NET Web Services (.asmx files), Web user controls (.ascx files), HTTP handlers
(.ashx files), and a few more ASP.NET application files such as the global.asax file. A pipeline
of run-time modules takes care of the incoming HTTP packet and makes it evolve from a
simple protocol-specific payload up to the rank of a server-side ASP.NET object—precisely,
an instance of a class derived from the system’s Page class. The ASP.NET HTTP runtime processes the page object and causes it to generate the markup to insert in the response. The
generation of the response is marked by several events handled by user code and collectively
known as the page life cycle.
In this chapter, we’ll review how an HTTP request for an .aspx resource is mapped to a page
object, the programming interface of the Page class, and how to control the generation of
the markup by handling events of the page life cycle.