I'm just starting to learn EJB. I started with the 3.0 version. Would it be recommendable to learn the version 2 prior to learning version 3 or can I deal with 3 without knowning any details about 2?
my honest advice is not to learn at all EJB 2. Of course you need to know the basics of the EJB container, which in part are unchanged, but in many areas the EJB are now developed differentely (and easily). The persistence is handled in quite a different way.
The above post says, you will find it of no use to learn EJB 2.x or anything less than that. You might try probably to just know the difference between the EJB 3.0 and it's prior versions but definitely not worth to invest time in EJB 2.x.