JDO has matured in one year

In the march towards higher levels of abstraction and more powerful coding approaches, Sun came up with Enterprise Java Beans several years ago. But despite one's best efforts, instead of focusing on writing business logic in a modular, fully encapsulated way, you often also have to deal with reading and writing to a persistent format; usually a relational database. The gritty details of the impedance mismathc between your [hopefully] object oriented approach and the latter might eat up too much of your time.

Realising this, Sun devised Java Data Objects. The book describes their main promise, which is to hide away the details of persistence. The big gain is in increasing the potential developer audience, as compared with EJBs. And you have less need of expert knowledge of RDBs. Previously, that was often a de facto requirement. You can now focus on the business logic. The second gain is shown in the JDO code examples, which are often cleaner without the persistence details. Of course, any realistic business logic will have more complicated details than the simple examples in the book, but at least persistence can be pushed offline.

Last year, Robin Roos wrote "Java Data Objects" [also by the same publisher]. At that time, JDO was just getting started. Now, Sun has moved it deeper into J2EE. There is a lot more support for transactions and JDBC. JDO is no longer a speculative fling.

Other Reviews

• Good JDO Overview
• A great book on JDO.
• Could have been better
• Don�t drop your JDBC yet!
• JDO has matured in one year