What is it that CMP/CMR architecture provides for that hibernate cannot
IHMO - nothing. CMP does have all the advantages (and disadvantages) of EJBs, but then so does Session Facade with a proprietory ORM behind it. However, Hibernate with a Session Facade however does have advantages over CMP e.g.: EJBQL it too limited to be of any real use, Entity Beans are not very portable being tied into a particular container, they are not Serializable so require DTOs, the n+1 problem, they reqire a one-to-one mapping to a DB entity which results in either a bad ER model or some very peculiar Objects, they requires a container, plus many other well reported problems.