In this Cloud Tutorial, we learned a great deal about the persistence of Java objects, beginning with the creating of entities from the classes of domain objects using annotations.

Instances of these classes can be stored in a database using the EntityManager, enabling them to be retrieved at a later date using the Criteria API or JPQL.

As part of this process, the conditions you have set in the entities using annotations are checked automatically via Bean Validation.

Finally, we needed a transaction context for the execution of database queries. This was created by converting services to EJBs. We’ll learn more about the interesting yet still largely unknown technology in the Cloud Tutorial EJB in a Day (to appear in march 2016).

If you want to deep dive into JPA, check the following references:

• Mike Keith, 2013. Pro JPA 2 (Expert’s Voice in Java). 2nd ed. 2013 Edition. Apress.
• Christian Bauer, 2015. Java Persistence with Hibernate. 2 Edition. Manning Publications

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