Java AppEngine: JDO or JPA, How to choose? [closed]

Question

Pros and Cons of choosing JDO or JPA for a Grails Application that will run on Google AppEngine

Answer 1

I do see why you would choose JDO. Don't know what is the "default" referred to by other poster. JDO is datastore-agnostic. JPA isn't. JDO allows fetch groups. JPA doesn't. JDO allows datastore identity. JPA doesn't. JDO allows datastore transactions. JPA doesn't. All of this is public record http://db.apache.org/jdo/jdo_v_jpa.html

JDO and JPA don't fill the same problem space. They overlap only for RDBMS. JPA is only designed for RDBMS.JPA is not simpler, as evidenced by the API comparison at http://db.apache.org/jdo/jdo_v_jpa_api.html

--Andy (DataNucleus)

Answer 2

If you are building for AppEngine the road is shorter and there are less hiccups if you use JDO. Else, you will have a JPA layer around your JDO engine.