As the JPA Expert Group (JSR-317) nears completion of the JPA 2.0 specification, this article introduces you to some of the new concepts and features in this updated specification. It also explains how you can experience this new functionality with the Apache OpenJPA project, an open-source, robust, high performance, scalable implementation of the JPA specification.

Criteria APIs will be great step to convert applications using stored procedures to use JPA. I will love to see support of subquery and subselect through Criteria APIs. We developed our own framework (SqlB) for Criteria APIs and worked already done on SqlB can be good reference for Criteria APIs in JPA.

It seems that there's no capability to override @GeneratedValue for subclass (of mapped superclass etc.) in JPA? If this is correct then I can argue lack of design consistency. @AttributeOverride allows for column to be overwritten for property/field and @Id. If column for @Id can be overwritten, which implies different tables, then someone should assume possible sequence/identity per table strategy. For legacy database this may be an issue. I have seen suggestions to move id field/method to subclass, but it is a workaround. I shouldn't have to do something that I wouldn't normally do to accommodate use of Java Persistence API. Any thoughts? Perhaps JPA specs group can look into it? Also, it would be nice not only to allow subclass to override attributes of properties/fields in mapped superclass but also to selectively disable mapping for such properties/fields.