How mature is Ebean or Siena?

Besides Ebean and Siena:

You can try JIRM which is focused on CRUDing immutable objects (yes I'm the author).

There is also jOOQ and Joist.

I feel that JIRM minimizes the number of DTO's because the domain objects are immutable and do not inherit, implement and/or are not "enhanced/instrumented". Such is not the same with Siena and Ebean.

Also because the objects are Immutable there is more of a focus on per column updating instead of the whole object which makes more sense given today's AJAX interfaces (compared to the old POST the whole bean model).

I'm currently a developer of Siena but not since very long. Let me explain why I became a developer on this project? I went to Siena because I wanted to use Play+GAE and Siena appeared to be a good start for GAE DB and I really wanted to avoid JDO/JPA. Then, I began to really appreciate Siena for its straightforward, light and easy approach and so simple APIs. It doesn't pretend to be the all-in-one abstraction layer like JDO and the greatest standard DB API like JPA. It really made me think of DB APIs from Python/Ruby and it really fits my point of view: I want a simple DB API which allows me to solve the great majority of my problems and when I have a more complex problem, I will use the lower layer APIs but certainly not an abstraction layer such as hibernate.

The possibility to make my code work on GAE DB or JDBC was also a good aspect. Once again, Siena doesn't pretend to provide exactly the same things in both worlds because SQL and NoSQL are not really compatible (but ORM is neither really compliant to SQL model :) ). But once again, it is quite practical to be able to rely on the same APIs in several DBs.

Finally, the library is ONE jar and you don't have to retrieve the whole universe to use it.

So, I became progressively a committer on Siena because I wanted to take part of this nice little adventure. Now siena team is working on a new version keeping the same simple APIs, bringing new interesting features and really improving all the backend code to make it even easier to extend for new DB support. Siena is a pragmatic API driven by user experiences and that's why I like it ;)

Pascal

Rob (Ebean Committer) here.

Ebean is about 4+ years old now. I would say it is fairly mature now. The supported DB's include Oracle, MySql, Postgres, H2 and SQL Server (and recently SQLite). Ebean is doing stuff that other ORM's are not such as Autofetch (automatic query tuning) so I'm not how that fit's into a 'maturity rating'. IMO the Ebean community is relatively small though so you probably need to hit the Ebean google group to engage them.

Any real world applications? Yes, but you are best to ask the Ebean community about that really. Certainly there is good support for batch processing (batch size, turn of cascading persist for a transaction etc) and large query support that I don't see in JPA etc (you might get something similar with Hibernate's Sessionless support).

Hopefully this might answer some small parts of your question anyway.

Cheers, Rob.

We've had really great experience with MyBatis, which is not an ORM per se, but another class of persistence manager, an SQL Mapper. Using it you start with SQL statements and direct it on how to map result rows into POJOs. It's conceptually easy to understand and tune with not much magic going on inside. It's ideal if you are comfortable with SQL or need to work with an established schema.