A short, clear list of what's new in JPA2?

Question

Does anyone know a good list of what's new in JPA 2? Not that new to Hibernate / TopLink in the version supporting JPA 2, but in the new specification.

Answer 1

The link mentioned in the accepted answer says nothing about the second level cache, so I decided to publish a quick list to summarize "What's New in JPA 2.0 (JSR-317)":

• Standard properties for persistence.xml - for example. javax.persistence.jdbc.driver etc. instead of the specific properties of the provider.
• Mixed Type Access Type - PROPERTY and FIELD can be mixed in a hierarchy and combined into one class.
• Derived identifiers . Identifiers can be obtained from relationships.
• @ElementCollection , @OrderColumn - for better collection support.
• Unidirectional @OneToMany / @OneToOne - for advanced mappings.
• Shared Cache API - Second-Level Caching in JPA, Yes !
• Lock - added support for pessimistic locking.
• Improved JP QL - Timestamp literals, non-polymorphic queries, collection parameter in IN expression, ordered list index, CASE statement.
• The expression and criteria API is QueryBuilder and CriteriaQuery for programmatically constructing security type queries.
• Additions API - additional API on EntityManager (supported properties, detach method, etc.) and Query (query hints).
• Validation Transparent Support Bean Validation (JSR-303) if a provider is present. (Validation is optional; JPA 2.0 specification does not require Bean Validation.)

Answer 2

http://java.sun.com/developer/technicalArticles/JavaEE/JavaEE6Overview_Part3.html#comjpa

Answer 3

Regarding this issue, the link may not be 100% accurate, but it is a very good source of information to get you started.