Rupen:
I am not familiar with Oracle 9i, however I own the the book, PL/SQL Programming for Oracle Database 10g, According to the book's index for scheduling tasks, the following is listed:
- DBMS_JOB
- Oracle Scheduler
- procedure execution on 30-minute interval
- purging e-mail table
This should give you a starting point, especially with the DBMS_JOB.
Hope this helps.