Using and Understanding Java Data Objects is an application programmer's guide to the Java Data Objects (JDO) specification recently accepted by the Java Community Process. JDO provides a universal and transactional persistence service for objects. JDO will store and retrieve objects of nearly any application defined class using any data storage technology for which a JDO implementation is available. JDO completely encapsulates the details of the underlying data storage technology that is used. JDO has its own query language (JDOQL) that allows the programmer to find objects based on the fields and relationships of the object model. The syntax of JDOQL is similar to the syntax of Java itself. JDO increases programming productivity by simplifying and minimizing the code that must be written to store and retrieve object state. The use of JDO also allows the application to be ported across different data storage technologies. Like the servlet and EJB specification, JDO is a standard that will be implemented by competing software vendors. Several JDO implementations are currently available as third party products for relational databases and object oriented databases. Using and Understanding Java Data Objects is a guide to the features and uses of JDO. Part I is a guide to the JDO API, the JDO metadata, and JDO's byte code enhancement. Part II explains the use of JDO in several application deployment scenarios, including stand-alone, client-server, servlet, and EJBs. Part III is a tutorial explaining the example programs and learning tools supplied with the book.

"Using and Understanding Java Data Objects" is a guide to the features and uses of JDO. Part I is a guide to the JDO API, the JDO metadata, and JDOUs byte code enhancement. Part II explains the use of JDO in several application deployment scenarios, including stand-alone, client-server, servlet, and EJBs.

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.

1. Overview.- 2. Basic Concepts.- 3. Queries.- 4. Transactions and Caching.- 5. Enhanced Classes and Managed Fields.- 6. The Persistence Manager and Persistence Manager Factory Interfaces.- 7. The Other Interfaces and Exceptions.- 8. Passing JDO Objects by Value.- 9. Designing the Business Service.- 10. Tutorial: Using JDO with a Local Client.- 11. Tutorial: Using JDO with EJBs, RMI, or SOAP.- Glossary.