hi
yes, it hapens whrn u r moving from one version to another.
When u compare weblogic 4.5 and 5.1
4.5 supports EJB1.0, 5.1 supports 1.1
(
EJB 1.1 supports xml and transaction is fine tunned)
I feel working with 5.1 more easy than 4.5.- no need of ser file, manifest file. jar will be created by your deployer tool in 5.1.
Hot deployment is damn easy in 5.1
hope this helps you.
alagan