Java Data Objects

Foreword

Java Data Objects (JDO) is an important innovation for the Java platform. At a time when developers were using JDBC almost exclusively for database access, and expert groups from major enterprise vendors were devising the much-touted Enterprise Java Beans APIs for entity beans and container-managed persistence, Craig Russell and David Jordan had the courage to take a different course. With a handful of others, they looked for a simpler way to provide persistence in the Java platform, something that would be both natural and convenient for programmers. This book describes the result of their work: JDO.

The key, unique idea behind JDO is to provide database persistence in Java with a minimum of extra stuff for the programmer to do. The programmer doesn’t need to learn SQL, doesn’t need to tediously copy data into and out of their Java objects using JDBC calls, and can use Java classes, fields, and references in a way that is natural to them, without lots of extra method calls and coding that is extraneous to the programmer’s focus and intent. Even queries can be written using Java predicates instead of SQL. In other words, the programmer just writes Java; the persistence part is automatic.

In addition to this transparent persistence, code written to JDO benefits from binary compatibility across implementations on different datastores. JDO can be used with an object/relational mapping, in which JDBC calls are generated automatically to map the data between Java objects and existing ...