Actually this is pretty close to what is done with MS ASP.NET AJAX and
similar frameworks like Anthem.Net. XMLHTTP calls are made to the page, the
page is processed through it's lifecycle on the server, and page methods are
called, with the results being marshaled via JSON back to the caller.
When you "Load" an aspx "file" what you are doing is allowing it to create
an instance of the Page class for that specific page. You can certainly do
this via Reflection API as well, since the codebehind for each page (at least
in a Web Application Project) is all compiled into the single assembly in the
/bin folder.
The .ASPX portion is normally compiled into a temporary assembly that
resides in the ASP.NET temporary files folder under the Windows
/Microsoft.NET/Framework/XXX / ASP.NET Temporary Files ... folder.
The bigger question here is : "What is the goal?" What are you trying to
accomplish, and why? There may very well be an easier way.
Peter