When to use EJB’s Required and Never transaction attributes,

Question

I refer to the attributes of container-managed transactions in Enterprise Java Beans. I can’t think of any use cases where the use of “Required” and “Never” makes sense. Can someone explain what cases require the use of these transaction attributes?

Answer 1

Here is my hit on this:

Required : EJB may provide some internal function that assumes / relies on the caller’s already completed transaction, and if not, cannot initiate it for various reasons, and therefore it will cause an EJB error. So the real question is why this would always be a requirement, and the only scenario I can develop will be where there may be specific transaction-related actions that should be performed at the start of the transaction, and some EJBs are not intended for these actions, and therefore marked mandatory. I suppose you can also use this attribute to provide consistent and properly ordered lock detection, when a failure to do so can lead to a deadlock.

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Answer 2

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Answer 3

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Answer 4

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