What's the difference between JPA and Hibernat

Question

I understand that JPA 2 is a specification and Hibernate is a tool for ORM. Also, I understand that Hibernate has more features than JPA 2. But from a practical point of view, what really is the difference?

I have experience using iBatis and now I'm trying to learn either Hibernate or JPA2. I picked up Pro JPA2 book and it keeps referring to "JPA provider". For example:

If you think a feature should be standardized, you should speak up and request it from your JPA provider

This confuses me so I have a few questions:

• Using JPA2 alone can I fetch data from DB by simply annotating my POJO's
• Is JPA2 supposed to be used with a "JPA Provider" e.g TopLink or Hibernate? If so, then what's the benefit of using JPA2 + Hibernate as compared to JPA2 alone, or compared to Hibernate alone ?
• Can you recommend a good practical JPA2 book. "Pro JPA2" seems more like a bible and reference on JPA2 (It doesn't get into Queries until the later half of the book). Is there a book that takes a problem/solution approach to JPA2?

Answer 1

JPA or Java Persistence API is a standard specification for ORM implementations whereas Hibernate is the actual ORM implementation or framework.

Answer 2

JPA is an API, one which Hibernate implements.Hibernate predates JPA. Before JPA, you write native hibernate code to do your ORM. JPA is just the interface, so now you write JPA code and you need to find an implementation. Hibernate happens to be an implementation.

So your choices are this: hibernate, toplink, etc...

The advantage to JPA is that it allows you to swap out your implementation if need be. The disadvantage is that the native hibernate/toplink/etc... API may offer functionality that the JPA specification doesn't support.

Answer 3

JPA is the dance, Hibernate is the dancer.

Answer 4

Hibernate is a JPA provider.

The page JPA Vs Hibernate by Krishna Srinivasan says:

JPA is a specification for accessing, persisting and managing the data between Java objects and the relational database. As the definition says its API, it is only the specification. There is no implementation for the API. JPA specifies the set of rules and guidelines for developing the interfaces that follows standard. Straight to the point : JPA is just guidelines to implement the Object Relational Mapping (ORM) and there is no underlying code for the implementation. Where as, Hibernate is the actual implementation of JPA guidelines. When hibernate implements the JPA specification, this will be certified by the JPA group upon following all the standards mentioned in the specification. For example, JPA guidelines would provide information of mandatory and optional features to be implemented as part of the JPA implementation.

Answer 5

JPA is a Java API specification which describes the management of relational data in applications using Java Platform. where as Hibernate is a ORM (Object Relational Mapping) library which follows JPA specification.

You can think JPA as a set of Rules which is implemented by Hibernate.

Answer 6

I try to explain in very easy words.

Suppose you need a car as we all know their are several A class manufacturer like MERCEDES, BMW , AUDI etc.

Now in above statement CAR(is a specification) as every car have common features like thing with 4 wheels and can be driven on road is car...so its like JPA. And MERCEDES, BMW , AUDI etc are just using common car feature and adding functionality according to their customer base so they are implementing the car specification like hibernate , iBATIS etc.

So by this common features goes to jpa and hibernate is just an implementation according to their jboss need.

1 more thing

JPA includes some basic properties so in future if you want to change hibernate to any other implementation you can easily switch without much headache and for those basic properties includes JPA annotations which can work for any implementation technology, JPQL queries.

So mainly we implement hibernate with JPA type technology just for in case we want to switch our implementation according to client need plus you will write less code as some common features are involved in JPA. If someone still not clear then you can comment as i m new on stack overflow.

Thank you