Question

I am gonna start learning EJB. I just need your suggestion on picking the version for learning EJB 2.0 or EJB 3.0. Is it good idea to start with EJB 2.0 and migrate to EJB 3.0? If it is, can it be easy to migrate? Actually I am holding Head First EJB book covering version 2.0. Suggest me any other good book, that I can stick to it for complete learning of EJB.

I am very grateful to you if you help me in becoming EJB Guru

Answer 1

I’d strongly recommend learning EJB 3.0 vs. EJB 2.0. It follows similar patterns to the popular ORM Hibernate. I don’t believe there’s much value in learning an earlier variant of EJB, when the current version follows commonly used ORM patterns and is supposed to be much simpler. From the FAQ:

The goal of EJB 3.0 is to target ease
of development, the main theme of the
Java EE 5 platform release. EJB 3.0 is
a major simplification over the APIs
defined by the EJB 2.1 and earlier
specifications. The simplified EJB 3.0
API allows developers to program EJB
components as ordinary Java objects
with ordinary Java business interfaces
rather than as heavy weight
components. Both component and client
code are simplified, and the same
tasks can be accomplished in a simpler
way, with fewer lines of code. Because
it is much simpler, EJB 3.0 is also
much faster to learn to use than EJB
2.1.

Since the two versions are so different, migration is next to impossible beyond the most basic concepts. Unless you have a specific requirement such that you need to look at EJB 2.0, check out the latest variant.