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what are nested transactions?

 
yamini nadella
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(1)EJB's don't support nested transactions.
Transaction means set of updates. but what are these nested trasactions?
(2)what are transaction isolation levels?
(3) if EJB bean has static variables then can't this EJB is portable? why?

Yamini
 
Nicholas Cheung
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(1)EJB's don't support nested transactions.
Transaction means set of updates. but what are these nested trasactions?

It means that, when the method is in a transaction, you cannot create a new one within that method.


(2)what are transaction isolation levels?

The transaction isolation levels are not specified in EJB spec, it depends on the database setting.


(3) if EJB bean has static variables then can't this EJB is portable? why?

Because different containers may use different means to treat this variable.

Nick
 
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