There are zillions of ways to do what you are talking about. FTP is not really the cleanest way and is only one way of many to do this. I would not use FTP on a production system. Here is an email example:
[list=1]
[]Email script to production server.
[]Production server processes and executes script.
[]Production server email results back.
[]Message from production server processed locally per requirement.
[/list=1]
A more 'super production' process could be set up using messaging queue software like IBM MQ or BEA MessageQ.
If you are going to do this 'on the cheap' then the email method could be set up in a few hours by anyone who understands the basics of processing incoming email messages on UNIX.