When you create a new instance of your ProductVO in flex, the primary won't be set but there will be an UID property which is an unique identifier. Once you commit to the Assembler and get it created to the db, populated the primary key with the new value and returned to the client, it will use the unique identifier to locate the local ProductVO and update it. The UID is then updated to the value of the primary key.
-- João Fernandes www.onflexwithcf.org www.riapt.org

