Please explain it about session beans instance passivation and conversational state from specifications
"An object that is not directly serializable, but becomes by replacing the references to an enterprise bean's home and component interfaces, the reference to the SessionContext object, the reference to the java:comp/env JNDI context and its subcontexts, and the reference to the UserTransaction interface by serializable objects during the object's serialization."
Suppose you have a Collection (say an ArrayList) of home interface references. I don't think the home interface references are serializable as they are in the Collection, so you will need to do something like this.
SessionContext is implemented by Container, it use the externalizable concept while passivation process that is it writes the sessionContext objects as binary stream objects which informations are enough for retrieve the equivalent sessionContext object when activation.These informations are container dependent.When activation it uses the information which written while passivation to construct the equivalent SessionContext object. Simmillar concept for other things also.