October 2003
Beginner
734 pages
16h 56m
English
Content preview from Head First EJB
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Things you must NOT do with BMT
A BMT bean must NOT start a transaction before ending the current transaction.
Brain Power
Imagine the implications of starting a new transaction before ending the current one. What might happen if you were allowed to do this?
Note
Nested transactions are not allowed in EJB!
You’re expected to know what the term “nested transaction” means, and what it might look like in code.
A BMT stateless session or message-driven bean must NOT complete a transactional method without ending the transaction.
Brain Power
Why are stateful session beans allowed to end a method without ending the transaction?
For a stateful bean, can you think of a scenario where you might want to do this (leave the transaction open)?
What might go wrong if you do this?
Note
Only STATEFUL session beans can leave a transaction open at the end of a method.
BMT transactions are one way: they can propagate out to a CMT bean, but no other transaction can propagate in to a BMT bean
Both BMT and CMT bean transactions propagate into a CMT bean.
A CMT bean can run in transactions coming from both CMT and BMT beans. ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.