How have you hooked into the On-Submit?

[oguruma1218]

I'm interested in extending this software to automatically send each submitted document/PDF to Amazon S3 (possible FTP and other transfer methods/protocols as well).

I have a client that needs offsite backups of certain Documents created automatically. So, once the Document is submitted, the PDF would be sent to Amazon S3/FTP.

Using your plugin, is there a way I can hook into the PDF creation and execute some code to send the PDF to where it needs to go?