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Mastering EJB 3.0
What's new with Mastering EJB 3.0:
More than 50% new and revised material
Four new chapters and one new appendix covering the latest features of the new release
Basic and advanced concepts (such as inheritance, relationships, and so on) of Java Persistence API defined entities
Information on integrating EJB applications with the outside world via the Java EE Connector technology
Tips and techniques for designing and deploying EJB for better performance
Best practices for EJB 3.0 application design, development and testing