>>>We drop text files into directories right now that are then picked-up by a listener in an external program. We would like to send them to a port instead. And listen to another port to pick-up what comes out of that external program. The other program already knows how to do this, but how do I send/receive stuff using ports in Foxpro? Thanks!
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>>What kind of ports (serial, parallel, USB, TCP, UDP)?
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>TCP? This is definately not my area of expertise, but I've been given the challenge of handling it. We are writing for default ports of 4444 and 1538 (i think) because they are supposedly rarely used. They will be able to change them though. Is that TCP?

If you have any users that use winamp and stream videos that uses port 4444.

Here is a couple of good listing of ports and what uses them.
http://www.iana.org/assignments/port-numbers
http://www.uponelevel.com/ports/

...I think there is a port listing on wikipedia has one too but its not as complete.