Do you mean that you DON'T have an XML file yet, and you want to
generate a test XML file to use with your program? If so, then as long as
you have a DTD or a Schema, then yes, you can generate test XML files. I
don't know of any open source solutions for that though. They all cost
money.

   Otherwise, all I can think of is that you want to somehow give data to
the XML file. Unless that XML file represents a program of some sort, I
don't see what it could do with the data. If the XML file IS a program, we'd
probably need more details on what it does to offer advice.

   - Oliver