This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori 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?