Working with MongoDB using Kundera

When we are talking about JPA2 we usualy imaging relation database and one of ORM (Hibernate or EclipseLink). However, JPA is general approach not only for relation system. It covers NoSQL as well. And one of wonderful JPA implementation oriented on non-relation databases is Kundera.

Initially Kundera was developed for Cassandra. It seems to be a good idea, if you don't use relation you don't have the main problem of different ORM frameworks:) HBase was the next database supported by Kundera, and now is the time for MongoDB

Also, support for relation schema was anonced! Awesome! Be honest, I don't believe the it'll work well. Otherwise we'll get power competitor to Hibernate and K.
But, Kundera is awesome one to creating prototype, when you need base CRUD operations and just to want to try you application with Cassandra, HBase or MongoDB. The beautiful parts is possibility to write JPQL queries instead of native database structures.

Let's figure out how we can use Kundera with MongoDb... Mongo JPA

EclipseLink

Had a chance to work with EclipseLink. If you are using Oracle and don't ahve any plans to migrate to other DBMS or support several DB at one time, you have to choose EclipseLnk, because it's defently better than Hibernate fot your aims.
Awesome things, not available in Hibernate:
1) All queries are generated with Oracle hints - it's can be useful and seems realy cool:)
2) Hierarchy queries are already supported
3) Much less open bugs in EclipseLink project
Also, EclipseLink is etalone JPA implementation.
Also, I love SQL logginig in EclipseLink. It perfect and has binding by default, also it's much more readeble that hibernate log (about logging http://wiki.eclipse.org/EclipseLink/Examples/JPA/Logging#How_To_Configure_Logging)