I think you're probably wrong that you can't handle it in stored procedures (packages). You may even be able to do a lot of the processing in a single SQL state

I think you're probably wrong that you can't handle it in stored procedures (packages). You may even be able to do a lot of the processing in a single SQL statement? Try this first, then PL/SQL. Do the bits you can't do in PL/SQL in a java class stored on the database...