Using and Understanding Java Data Objects is the programmer's guide to JDO. Adopted by the Java Community Process, Java Data Objects (JDO) specifies a universal and transparent persistence service for Java objects. JDO reduces the amount of code that application developers write to store and retrieve persistent state. JDO frees application designers and programmers from the details of persistence. As a result, designs can be more object-oriented, programmers can be more productive, and applications can be more robust and flexible. This book has two missions. The first mission is to give you a tour of JDO. During this tour, author David Ezzio attempts to give you the benefit of his 2 years' experience learning about JDO and using it to build some fairly simple, but demanding applications. The second mission is to give you a tour of the open source JDO Learning Tools. Some of these tools poke and prod JDO so that you can learn more about its behavior. Other tools are examples of three application architectures. Separate chapters and examples cover client-server applications, web applications, and applications using Enterprise JavaBeans.