2nd send - talking to web front end

Hi there.
 
I sent this to fourjs-users a short time ago, then found I was no longer
subscribed to the mail list, and wasn't sure it had posted.
Re-subscribed and re-posted.  If it posted already, sorry for the
repost.
 
-----------------------
 
This is probably a very simple question, but I've never had to do this
before.
 
I have 4js apps using the Web Front End to support our administrative
intranet.  External customers of mine would like to be able to query my
system and get an answer.  Basically, they would like to say "given A, B
and C, what is X?"
 
I can give them a little javascript that connects to my fglccgi, calls
the appropriate module and passes A, B and C as parameters.  But how do
I send the "X" back to them?
 
This seems like it ought to be so simple that I'm kind of embarrassed to
ask.
 
Thanks,  Ray Garrison