Hi!
In our environment, I would use APD (possibly in a process chain with RSAN_PROCESS_EXECUTE) and create the file on our application server.
Then we would transfer the file with FTP using an automation tool. Our basis team is using Automic. Yours may have a different solution.
Alternatively you could try to transfer the file in ABAP. Some possibly useful links, though I haven't checked them in detail:
Working with FTP Server - ABAP Development - SCN Wiki
Performing FTP Commands From ABAP
I would strongly recommend contacting your basis team concerning the ftp transfer. There might be some regulations forcing you to use Secure FTP for example.
Best regards,
Reinhard
http://wiki.scn.sap.com/wiki/display/ABAP/Working+with+FTP+Server