| Callback interface for JDO code. To be used with
JdoTemplate 's
execution methods, often as anonymous classes within a method implementation.
A typical implementation will call PersistenceManager CRUD to perform
some operations on persistent objects.
Note that JDO works on bytecode-modified Java objects, to be able to
perform dirty detection on each modification of a persistent instance field.
In contrast to Hibernate, using returned objects outside of an active
PersistenceManager poses a problem: To be able to read and modify fields
e.g. in a web GUI, one has to explicitly make the instances "transient".
Reassociation with a new PersistenceManager, e.g. for updates when coming
back from the GUI, isn't possible, as the JDO instances have lost their
identity when turned transient. This means that either value objects have
to be used as parameters, or the contents of the outside-modified instance
have to be copied to a freshly loaded active instance on reassociation.
author:
Juergen Hoeller
since:
03.06.2003
See Also: JdoTemplate
See Also: JdoTransactionManager |