Java Data Objects (JDO)

Introduction

Most applications and server-side components move data between objects in memory and persistent storage. The JDO standard specifies a transparent persistence service for Java objects. It also defines a general framework for storing and retrieving the persistent state of Java objects.

Java programmers use tools to make their projects successful. JDO promises to change the way that Java programmers store and retrieve object information. It also simplifies application software and increases its portability. Compared to any alternative, JDO makes persistence easier to understand, easier to model, and easier to code.

JDO Benefits

• JDO is completely specified as database infrastructure, and has no ties to any Java middleware implementations. That is, you can use JDO from any Java middleware implementation, such as Enterprise Java Beans, Web Services, Servlets, JSPs, etc.
• JDO's strength lies in its transparency, which lets you create persistent business objects without needing to place persistence-related code in application classes. Since the JDO vendor handles this persistence, there is no need to write persistence infrastructure.
• The JDO specification is well thought out, and it includes both object life-cycle states and transactional semantics.
• JDO eliminates the need for hand coding SQL.

ObjectRiver has built an implementation that complies with JDO 1.0.1 and parts of the yet to be released JDO 2.0 industry specification. ObjectRiver is not a pure JDO vendor, and its implementation varies from a typical JDO vendor in a few distinct ways.

• The ObjectRiver JDO implementation only persists business objects that are modeled.
  
  In the ObjectRiver system, the data model defines the physical and relational mapping, and this model is based on your business requirements. Typical JDO vendors use the Java language as the model for persisting Java objects. This requires them to do an Object to Relational (O2R) mapping. This mapping creates relational schemas that are not acceptable for enterprise data integration projects.

• ObjectRiver completely generates the Java Data Objects that your model defines. There is no need for class file enhancements to your code. (The JDO specification does not require class file enhancers, and we believe that class file enhancement only complicates the implementation.)

JDO is the best-specified industry standard for object persistence today, and it is ideally suited to the ObjectRiver architecture. From the modeled business objects to the business event objects, persistence is completely transparent.

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