April 2003
Beginner to intermediate
380 pages
12h 25m
English
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Lifecycle States
JDO has a total of 10 lifecycle states. The following 7 states are required:
Transient
Persistent-new
Hollow
Persistent-clean
Persistent-dirty
Persistent-deleted
Persistent-new-deleted
There are also three optional states:
Transient-clean
Transient-dirty
Persistent-nontransactional
If a JDO implementation does not support the transaction-related optional features that allow transient transactional and persistent-nontransactional instances, these three optional states are not reachable. This chapter focuses on the required states. Chapter 13 and Chapter 14 discuss these optional features and associated lifecycle states.
Transient
When you call a constructor to create an instance of a class, the instance is placed in the transient state. Each instance created by the application starts its life as a transient instance. Transient instances do not have a JDO identity, because identity is only a characteristic of persistent instances. A transient instance should behave exactly as an instance of the class would if the class were not persistent. No JDO exceptions are thrown for a transient instance.
Many developers wonder how much overhead is involved when transient instances of an enhanced class are manipulated. Fields of transient instances have slightly slower access and modification than they would if the class were not persistent and enhanced. No mediation of access or modification of fields is performed on instances in the transient state. In particular, a transient instance never ...
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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.