This figure illustrates the relationship between entity architecture
elements. A Persistence class can create one or more
EntityManagerFactory objects. An EntityManagerFactory object can
create one or more EntityManagers. An EntityManagerFactory is
configured by one Persistence Unit. The properties defined by the
Persistence Unit are inherited by the EntityManager. The Persistence
Unit defines the Persistence Context. The Persistence Context is the set
of managed Entity instances within the EntityManager. One or more
EntityManagers can manage a Persistence Context.