Hello Ross,
Yes, you need a servlet that gets the submitted info from PDF, and then that servlet internally need to invoke your process.
There are couple of ways you can submit the data to your servlet, either as PDF/XML/XDP. If you are looking for submitting PDF/XDP, then one need to have either Acrobat S.W (Standard or Professional) or you need to apply ReaderExtensions on those PDFs.
Hope I answered your questions.
Regards
Sivajee