Reverse Engineering Appliction Help!!

Hi,

I'm a final year student and am doing a project which entails writing a Java prototype application to reverse engineer an Oracle database (extract Entities, Relationship and Multiplicity between those related entities) and draw an ER diagram.

My biggest problem at the moment is 'how do I extract multiplicity, both cardinality and participation, from the database'?

In essence this question should read 'how does the multiplicity shown at the contextual (ERD) level relate to the final database model'?

If you could suggest any ways I could answer this question then I would be most grateful.

Also, a lot of the scripts I've seen to extract the primary and foreign keys have been very complicated and some have been very simple..is there a definative script out there to do what I want?

Regards,

James