Debugging triggers.

Hi All,

I'm trying to debug some errors which happens during a chain of events
(user does some updates which fires triggers and calls some stored
functions).
I would like to get a system dump (eg. content of tables) at the point when
the error occurs as everything is rollback'ed on error.

The system I'm working with looks like the following:
    web browser -> jsp/servlet/dbms-api (on solaris) -> oracle 8.1.6 on
solaris

I started looking at the web on triggers debugging. There are a lot of
mentions of DBMS_OUTPUT.
However, I could not quite get this to work.
(Do I need to do DBMS_OUTPUT.get_lines in order to get the output produced
by a different session?)

I am hoping someone can points me to resources about triggers/functions
debugging,
especially ones that contain some examples.

Thank you in advance,

Lucy