This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
I used Hibernate and JPA and a little of Toplink. But I never used JDO and I don't know how it is. Do yo cover JDO in you book and how it is related with the other ORM technologies specially wich is the diference with JPA?