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What is Session Bean. What are the various types of Session Bean
Answer posted by Mohan on 2005-05-20 08:44:39: SessionBeans typically are used to represent a client they are of two typse Stateful Session Beans : they maintain conversational state between subsequest calls by a client Stateless Session Bean : consider this as a servlet equivalent in EJB. It is just used to service clients regardless of state and does not maintain any state....
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Is there a way to get the original exception object from inside a nested or wrapped Exception (for example an EJBException or RemoteException)
Absolutely yes, but the way to do that depends on the Exception, since there are no standards for that. Some examples: ·When you have an javax.ejb.EJBException, you can use the getCausedByException() that returns a java.lang.Exception. ·A java.rmi.RemoteException there is a public field called detail of type java.lang.Throwable ·With a java.sql.SQLException you need to use the method getNextException()...
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What is local interface. How values will be passed
Answered by Jey on 2005-05-08 12:33:35: If Client and EJB classes are in the same machine ( Same JVM) then we can use Local linterface instead of Remote interface. Since Client and EJB are in same JVM, values are passed by referance.
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What are the various isolation levels in a transaction and differences between them
Answered by Jey on 2005-05-08 19:35:35: There are three isolation levels in Transaction. They are 1. Dirty reads 2.Non repeatable reads 3. Phantom reads. Dirrty Reads If transaction A updates a record in database followed by the transaction B reading the record then the transaction A performs a rollback on its update operation, the result that transaction B had read is invalid as it has...
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