anonymous wrote : Persistence context != transaction context. That is why there are two different things. Ok, so objects may be attached to the Entity Manager and not participate in a transaction. But how come that changes made to attached objects are reflected in the database? And when does a transaction start and end when we are using a persistent entity manager? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3990377#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...