How to correctly skip executiong of .aspx from a HTTP module

[Gabriel Lozano-Morán]

Here is my problem description:

We have a Java Portal from there a user can click on a certain aspx page.
There is some kind of authentication mechanism that can be compared to a
challenge-response authentication where a Java Servlet asks me for something
with a HTTP Post and I have to respond to that request and in return the
Java Servlet will retrieve the page again but this time using a HTTP Get.
The problem is that when I answer with the Response object from within the
HTTP module the aspx page will still be processed. If I want to skip
processing the request by issueing a Response.End() or an
Application.CompleteRequest() the response is never sent to the Java
Servlet. I have the impression that when I end the request from within the
HTTP something vital is not set to the client, something that will be sent
when I let the aspx process the request.

Using Reflector I noticed the following in the System.Web.HttpResponse:

internal void FinalFlushAtTheEndOfRequestProcessing()
{
this.Flush(true);
}


Please kan someone answer what exactly goes wrong here and how I can skip
the processing of the ASPX page? I can provide you with more information if
needed. Please don't give me workarounds as I am fully aware that I can work
with a HTTP handler but these are processed too late in the pipeline of the
HTTP request.

A million thanks to anyone who can help me out in any way