also have a look at the oracle  documentation regarding the JVM
executed by the Oracle DBMS kernel itself. Are you a member of the
Oracle Tech Network (OTN)? If not, log in to http://otn.oracle.com
and sign up as a new user; then you have access to lots of
documentation, among which you should also find doc's about Java on
Oracle. They have integrated a JVM into the Oracle kernel since 8i.
Unfortunately I haven't had the time  to cope with this subject yet,
so I can't give any direct advice.