If you enjoyed this article, you might also want to check out the ongoing
webinar series from SolarMetric, the makers of Kodo JDO.
The free 3 part series consists of:
[list]Introduction to JDO - an introduction to the Java Data Objects standardAdvanced JDO Concepts - advanced topics including using JDO in J2EE environmentsImproving Scalability and Performance Using JDO - another advanced presentation on how to leverage caching and other tools to improve performance and scalability of enterprise class Java applications
Also, available is a free PDF of Robin Roos' Java Data Objects book.
Please note that registration is required to download the book or attend the webinars.