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Review by : Ernest J Friedman-Hill
Rating : 8 horseshoes </pre>
Java Data Objects is simple and straightforward, and solves a real problem in an elegant way. Conveniently, this also serves as a description of this enjoyable book from some of the key JDO specification team members.
JDO is a recently standardized API for transparent object persistence. A standalone reference implementation is available, as are quite a few commercial and open-source versions that piggyback on relational databases and other storage solutions. JDO's popularity is growing rapidly because of its simplicity, ease of use, and scalability. "Java Data Objects" is a timely and practical treatment of this new API.
After a clear and accessible overview, this book first presents JDO in a tutorial style using a simple but nontrivial example application. Later chapters fill in the details where needed: for instance, a whole chapter is dedicated to the difficult topic of object identity.
The motivations behind JDO's development are explained well, and comparisons to other object-persistence solutions, including
EJB container-managed persistence, are fair and balanced. One of this book's few flaws is that despite the authors' important roles on the standards committee, the rationale behind some of JDO's more puzzling properties are left unexplained. In particular, JDO requires that only a small subset of the standard Collections be supported by a JDO implementation, but this book doesn't explain how this subset was chosen.
All in all, an excellent tutorial and reference that will have you up and running with JDO in no time.
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