ASP And Worldpay Callback

My understanding is that after a transaction Worldpay will send the
result's to a specified URL. All of the scripts I've looked at parse
the query string and display the data onto a web-page, which obviously
renders a page, as there is no one to read this and it does not go to
the client I'm not sure what use these scripts are.
I have a couple of general ASP questions if anyone has a solution
How do you make a call to an asp page that updates a database but does
not render a page? I'm probably being dumb but what does the url look
like? I.E can I make a call direclty to a web-service to update my DB.
I'm running dot.net framework 1.1, MCMS 2002 and using visual studion
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