Which ORM tool is better?

Is another free ORM tool better then the two?

OJB supports JDO. However, Hibernate seems really really popular.

I've been using Hiberate for 4 months now. Its easy to use and gets the job done. Thanks to Hiberate's excellent documentation, the learning curve is not steep. Hibernate's team is very active in the Hibernate Forums.

If you look at the Hibernate road map, they have some interesting things planned for Hiberate 2.1 . If i remember correctly, some people are working on including Swarm cache for distributed caching in clusters.

I think they are both pretty strong. Some of the points made have been that Object/Relational Bridge is more "architected." And there is a strong pluggable architecture with support for ODMG, the Object/Relational Bridge PersistenceBroker, and JDO. Pluggable caches, and all sorts of other goodies. On the other side, Hibernate gang likes to say they do "one thing really well." So it depends on what you want it for.

I wanted to standardize a persistence mechanism for my group (Northwest Alliance for Computational Science and Engineering). So I chose Object/Relational Bridge, because I wanted maximum flexibility/extensibility.

I think they neither offers API's/features that the other doesn't in terms of database functionality though.

By the way: Object/Relational Bridge already supports distributed/clustered caching with either Tangosol Coherence (Commercial) or OpenSymphony's OSCache.

Jason McKerr
Northwest Alliance for Computational Science and Engineering

Gaving King said in the interview (Tech Talks & Events) that JDO lacks of some important features and that he won't implement JDO because of that.

I also like that the bytecode enhancement is done at runtime in Hibernate and not at design time like in JDO implementations.

He seems to know what he is doing and since he is the only Hibernate architect, there is conceptual integrity.

There are so many small things which make it easier to the programmer. Gavin King seems to know about these things and it seems they are implemented in Hibernate.

On the other side, Sun makes JDO an industry standard which Hibernate is not.

I think I'll try to provide support for both persistence technologies in my framework.

Ibatis is an excellent framework for mapping relational databases to objects and vice versa. You have the flexibility to write your own sql but none of the hassles of mapping the results to objects, lists or maps. Can easily add or swap out databases if required, reuse sql etc etc.

Documentation is excellent.

Worth a read at www.ibatis.com
or a tutorial
http://www.reumann.net/do/struts/ibatisLesson1

Angus.