今天由于某种原因，稍微关注了以下JDO——这个我一贯不怎么看好的东西。其实早在4、5月份JDO 2.0（JSR243）已经做完了JSR Review Ballot，而且最重量级的三个厂商都投了反对票。看看他们的comments倒是很有趣的。
On 2004-04-26 BEA Systems voted No with the following comment:
JDO is one of many different persistence solutions in server-side Java today. With J2EE 1.5 emphasis on simplification and ease of use, we don’t see how having another release of JDO, whose market acceptance is essentially constrained to use with object databases, can be explained in conjunction to similar enhancements being made in the EJB3 expert group. We are also concerned about taking JDO into new areas such as disconnected data set support until we better understand how ball of these solutions fit together. Unless the submitters can explain how all of this fits together, we believe the Java community would be better served with fewer apparently competing alternatives.
On 2004-04-30 IBM voted No with the following comment:
This JSR proposes to develop extensions to JDO that apparently overlap with existing Java technologies and with other JSRs that are already in-progress. In a context where the Java community is working to simplify J2EE, it is undesirable to produce multiple overlapping ways of programming the same function.
On 2004-05-03 Oracle voted No with the following comment:
JDO 2.0 overlaps with the work being done by the EJB 3.0 expert group to provide a lightweight persistence model. Having 2 specifications address the same problem space with different APIs, persistence and transaction semantics, mapping definitions and query mechanisms does not contribute to the effort of simplifying J2EE and making it easier to use. The direction of lightweight persistence being taken by the EJB 3.0 group will have tremendous appeal to mainstream enterprise Java developers, even those who are critical of the current Entity Bean model. Given the evolution of EJB 3.0 persistence, another independent standard for persistence is unnecessary and will add confusion to those looking to adopt J2EE technology.
也就是说——等待EJB 3吧，把JDO扔到一边去，或者不如就用Hibernate算了。
这是很老的新闻了，不过现在我们还是没有一个真正让人放心的persistence solution。这不能不说是Java社区的悲哀。即使活跃的Hibernate也因为JBoss的加入而令人担心起来。。。