The primary key type must be a legal Value Type in RMI-IIOP
It's mean that primary key must implements Serializable interface when you give composite primary key, than it's become a legal value in RMI-IIOP and an other hand i guess that primary key can't be primitive values once you must return null for ejbCreate method at the bean ...
RMI-IIOP compliant value is valid as long as it is shippable. It can be primitives, serializable objects, an array of primitives/serializable objects, or a remote object. For entity bean, since a create() method must return null, the primitive option is eliminated. The spec further restricts the data type of primitive key ???
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