How is object level replication done in the database. i.e.

in my database there two different users. i want that the schema of the respective users should contain the same objects, and any object manipulation either DML or DCL or DDL applied in the schema objects of either of the users should automatically get reflected in the schema objects of the other user. how do i set up such a scenario. i know this thing can be done in Oracle 8i as because i have heard about it but i don't know how to proceed about doing it.