How to change the .aspx extension

I would like to use a different extension for my
.aspx pages, say, .sp, or .a. Is there a way to configure
this using IIS?

I know, right now, only .aspx extensioned URLs make it
into my application_request() in my global file.

You could try using the IIS management console, inspect the mapping setting for .aspx and clone that to a new mapping for a different extension. I've never tried this, I don't know that it will let your other extension get processed by NET but it might.

I tried this without success. The file is simply served as plain text. Has anyone else tried this?

Nevermind, I found it. In addition to associating the extension to the aspnet_isapi.dll file for IIS, you must also associate the extension to a specific handler for aspnet. This can be done in the web.config file of the project like this:

<system.web>
<httpHandlers>
<add verb="*" path="*.myext" type="System.Web.UI.PageHandlerFactory"/>
</httpHandlers>

In this case, the *.myext files will be treated like aspx files. Look in machine.config for other examples of what can be done.