For years, the Enterprise JavaBeans (tm) (EJB (tm)) and (tm) Java Data Objects (JDO) specifications have evolved independently as they addressed different sets of requirements. The core of both specifications, however, includes persistence technology. Even to this day, the data persistence models in EJB and JDO differ significantly. This divergence has caused confusion and debates among Java developers, and is not in the best interest of the Java community. Consequently, requests to put an end to this unwanted divide have poured in from members of the Java community. in response to these requests, Sun Microsystems is leading a community effort to create a single POJO (Plain Old Java Object) persistence model for the Java community. This effort will strengthen community solidarity.
Starting this reconciliation effort now is very timely given that both the EJB and JDO specifications are going through significant revisions. As specification leads for EJB 3.0 (JSR-220) and JDO 2.0 (JSR-243), we have jointly created the following plan to Move this Community Effort Forward:
This is a community effort. We are expanding the JSR-220 Expert Group to include some members from the JSR-243 Expert Group. By joining forces, we will bridge the two communities and leverage the know-how in both groups. The current JSR -220 specification lead will remain unchanged. The work to define a single POJO persistence model for the Java community will be done under JSR-220 starting from the existing JSR-220 Early Draft. The technical objective for this new POJO persistence model is to provide a single object / relational mapping facility for all Java application developers that works in both J2SE and J2EE. The work will be done within the J2EE 5.0 time frame. The new POJO persistence model will be delivered by JSR-220 as a separate specification, Reference Implementation, and Technology Compatibility Kit, usable independently of EJB 3.0. As currently planned, the scope of JSR-243 will include maintenance to JDO 1.0.1 and enhancements to JDOQL. Additionally, the JDO expert group w ill aim to deliver JDOQL that would work with the new POJO persistence model so those with a preference for JDO query style can leverage the new common persistence API. The current JSR-243 specification lead will remain unchanged.We believe this is a unique opportunity for the Java community to create a common POJO persistence model for both J2SE and J2EE. Some of the industry's best minds will be collaborating to agree upon this standard. By incorporating best-of-breed design concepts, this common POJO persistence model will further strengthen the Java Platform.
We are asking the entire Java technology community to support us and the efforts of the JSR-220 Expert Group. We'd like to encourage everyone to contribute to the direction of this persistence work by reviewing the specification drafts and sending us your feedback. Your Input is crucial to the contact surcess of the java platform.sincelely,
Linda Demichiel and Craig Russellspecification Leads, JSR-220 and JSR-243 ------------------------------------ -------------------------------------------------- -------------------------- 代文 http://java.sun.com/j2ee/letter/persistence.html
