persistencia y transacciones

These are your primary programming interfaces in Java Persistence:

■ javax.persistence.Persistence—A startup class that provides a static method for the creation of an EntityManagerFactory.

■ javax.persistence.EntityManagerFactory—The equivalent to a Hibernate SessionFactory. This runtime object represents a particular persistence unit. It’s thread-safe, is usually handled as a singleton, and provides methods for the creation of EntityManager instances.

■ javax.persistence.EntityManager—The equivalent to a Hibernate Session. This single-threaded, nonshared object represents a particular unit of work for data access. It provides methods to manage the lifecycle of entity instances and to create Query instances.

■ javax.persistence.Query—This is the equivalent to a Hibernate Query.
An object is a particular JPA query language or native SQL query representation, and it allows safe binding of parameters and provides various methods for the execution of the query.

■ javax.persistence.EntityTransaction—This is the equivalent to a Hibernate Transaction, used in Java SE environments for the demarcation of RESOURCE_LOCAL transactions. In Java EE, you rely on the standardized javax.transaction.UserTransaction interface of JTA for programmatic transaction demarcation.