I'm not a spring specialist.. I will just speak about my own experience...
I will reply according to what we usually use in my company. The typical architecture we are using :
- Database : PostgreSQL because it can easily deal with 1 GB database.
- Persistence layer : Hibernate because it's easy, efficient and don't miss any features (unlike CMP).
- Services layer : Session EJB because they handle transactions, security and communications.
- Presentation layer : Struts because it's an industry choice but we plan to move to JSF.
*EJB 2.1 + xdoclet seems exceeded and dont' like it; it is however best to use it because IDE and support is better tested and more diffusd?*
We really love XDoclet to develop our stateless bean. We don't have IDE support for it but it's not really needed. Our statless bean source looks like POJO thanks to xdoclet.
*I heard about Spring as a new filosophy, i must belive on it? *
Seems it's quite nice indeed...
*Than, if i study EJB 3 i must improve also Hibernate 3 or is inside Ejb technology?*
I'm not sure if the question but i think u should concentrate on Hibernate 3 and wait for the EJB spec to be "done".