JPA Method
in javax.persistence.EntityManagerFactory

EntityManager createEntityManager(
  SynchronizationType synchronizationType, 
  Map map
)

Create a new JTA application-managed EntityManager with the specified synchronization type and map of properties. This method returns a new EntityManager instance each time it is invoked. The isOpen method will return true on the returned instance.
Parameters:
synchronizationType - how and when the entity manager should be synchronized with the current JTA transaction
map - properties for entity manager
Return:
entity manager instance
Throws:
IllegalStateException - if the entity manager factory has been configured for resource-local entity managers or is closed
Since:
JPA 2.1