Non Relative Includes

I want to include a file that isn't relative to my document.

for example:

PHP Code:

---

<!--#include file="http://www.websiteaddress.com/showpage.asp"--> 


---

which I know doesn't work using an address that isn't relative, but what other code can I use to do this?

In Perl and PHP you would use the server path
/var/www/html/include.file
instead of the browser url
http://www.websiteaddress.com/include.file

It's probably the same for ASP.