>>>Next, the XML data file needs to be sent ("forwarded") to another client computer on this WAN. My client-side application watches for incoming XML files and updates its' free tables when XML files are found in a specific directory.
>>
>>If your solution is thus far file based, and the client machines are on the same network, then the simplest solution would be to allow the server to access drives on the client via UNC, and just copy the file:
>>
>>COPY FILE "c:\myxml.xml" TO "\\Client1\SomeShare\SomeFolder\myxml.xml"
>
>That was my first idea, but I was wondering if UNC names are not available, is there an "IP address" equivalent?

You can substitute the IP address of the machine for the Machine name:

COPY FILE "c:\myxml.xml" TO "\\123.123.123.123\SomeShare\SomeFolder\myxml.xml"

Just makes sure that the server has sufficient rights to copy a file onto the client machine.