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  • Breaking Now

    How EJB evolved over the years?

    The evolution of EJB can be captured in following points:
    1.0:

    - No mandate that Entity EJB must be supported by EJB container
    - EJB communication backbone uses RMI-JRMP(Java Remote Method Protocol)
    - No CMP Entity EJB
    - No Deployment Descriptor XML file, used compiled class, then serializes it into flat file (binary).
    1.1:
    - Entity Bean supported by EJB container
    - has CMP, but never describe how to configure relationship between CMP Entity EJBs, this depends on container tool provided by vendor
    - RMI-IIOP is suggested for EJB communication
    - Deployment Descriptor XML file was introduced
    2.x:
    - Message Driven Bean is introduced
    - With CMP, you can configure the relationship between CMP Entity EJBs, in ejb-jar.xml
    - EJB-QL for CMP EntityEJB query language
    - RMI-IIOP is a must for EJB communication
    3.0:
    -No more deployment descriptor,metadata annotations used instead.
    -CMP simplified.It is more like JDO or Hibernate.
    -Checked exceptions are reduced.RemoteException is no longer mandatory with each remote business method .
    -Inheritance is allowed and a bean can extend some base code.
    -EJB-QL enhanced.

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