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== JDO Class Typesanchor:JDO_Class_Types[]

JDO provides a means of transparent persistence of objects of user
defined classes. With JDO there are actually 3 types of classes.

* *Persistence Capable* classes are classes whose instances can be
persisted to a datastore. JDO provide the mechanism for persisting these
instances, and they are core to JDO. These classes need to be _enhanced_
according to a JDO Meta-Data specification before use within a JDO
environment.
* *Persistence Aware* classes are classes that manipulate Persistence
Capable instances through direct attribute manipulation. These classes
are typically enhanced with very minimal JDO Meta-Data. The enhancement
process performs very little changes to these classes.
* *Normal* classes are classes that aren't themselves persistable, and
have no knowledge of persistence either. These classes are totally
unchanged in JDO, and require no JDO Meta-Data whatsoever.

=== PersistenceCapableanchor:PersistenceCapable[]

Classes are defined as *PersistenceCapable* either by XML MetaData, like
this

....
<class name="MyClass">
    ...
</class>
....

or, in JDO2.1, using Annotations. Like this

....
@PersistenceCapable
public class MyClass
{
    ...
}
....

{empty} +


=== PersistenceAwareanchor:PersistenceAware[]

Classes are defined as *PersistenceAware* either by XML MetaData, like
this

....
<class name="MyClass" persistence-modifier="persistence-aware"/>
....

or, in JDO2.1, using Annotations. Like this

....
@PersistenceAware
public class MyClass
{
    ...
}
....

{empty} +