Simple Object Persistence with the db4o Object Database (11 tags)
Mapping Java objects to relational databases is a difficult task, fraught with perils and gotchas. db4o dodges the issue entirely by providing an object-oriented persistence mechanism that is small, lightweight and efficient. Jim Paterson shows how it works.
Agile Object to Relational Database Replication with db4o (10 tags)
Start with the idea of an object database, like db4o, which effortlessly persists arbitrary objects, even those with deep structures, into a database. Then mix in a little Hibernate. Now you can map objects to either the db4o database or a relational database. And as Jim Paterson shows, the db4o Replication System allows you to do some interesting things, even replicating between two relational databases, using db4o in the middle.