On one of our projects we decided to switch JPA providers from Hibernate to Toplink. The main reason for this was that Hibernate depends on so many core open source libraries that other open source projects also use, that there are all kinds of version problems when the application is deployed in a JEE container, such as Tomcat or Glassfish, that uses different versions internally. Basically jar hell with all kinds of issues with classloaders loading the wrong version of the jar.

We use hibernate on our projects for the ORM technology. We are starting to use EJB3 now for all new development. Luckily its very similar to hibernate so we don't have to re-skill too much.

Hibernate HQL Inner Join

An issue that I came across recently was hibernate's HQL language inability to handle "inner join on" clauses. If your domain entity model has relationships defined between the related objects then something like