JDO 2.0 Sunday, December 19, 2004

The Public Draft of JSR-243 is available for download at http://jcp.org/en/jsr/detail?id=243. This JSR is defining the JDO 2.0 spec.

There is a lot of new and cool stuff being proposed for 2.0. One item in particular that I am interested in is the whole detachment idea. The idea is that we would be able to detach a persistent object from the data store, modify the object and then later re-attach that object and commit the changes. The changes could be commited by a different PersistenceManager and could even be committed in an entirely different VM.

Another nicety proposed for 2.0 is the formalization of O/R metadata for defining indexes, foreign keys and constraints. Some JDO implementations already support this sort of thing via vendor extensions in the meta data. ObjectDB uses this approach. Other implementations suggest that you let their tool create the tables and columns and then you go in after the fact and define your indexes, constraints etc. in the database yourself. TJDO takes this approach. It will be nice to have this formalized in the metadata for portability.