JDO is easy, Alvin... It's not a new concept... It's simply persistence
Java objects, to reduce network communication... It's a best practice to use this concept in
J2EE applications...
Hope
this article might be useful for you as well...
Co-author of SCMAD Exam Guide, Author of JMADPlus
SCJP1.2, CCNA, SCWCD1.4, SCBCD1.3, SCMAD1.0, SCJA1.0, SCJP6.0