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https://issues.apache.org/jira/browse/JDO-615?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12652505#action_12652505
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Craig Russell commented on JDO-615:
-----------------------------------
Just some high level comments for right now.
In order to mirror the xml metadata, you would need to start with a top level
metadata root, corresponding to the jdo element. You could construct this from
the JDOHelper, e.g. public JDOMetadata newJDOMetadata();
Then, JDOMetadata would have methods newPackageMetadata(String name),
newQueryMetadata(String name), and newFetchPlanMetadata(String name).
PackageMetadata would then have methods newInterfaceMetadata, newClassMetadata,
and newSequenceMetadata.
If you use method chaining instead of constructors, then you could change this
example to be more self-describing:
ClassMetaData cmd = dmdf.newClassObject(pmd,"Client",
IdentityType.DATASTORE.toString(), null,
Boolean.TRUE.toString(), Boolean.TRUE.toString(),
Boolean.FALSE.toString(),
ClassPersistenceModifier.PERSISTENCE_CAPABLE.toString(), null,
null, null, "CLIENT", null);
pkgMetadata.newClassMetadata("Client")
.setIdentityType(IdentityType.DATASTORE)
.setPersistenceCapableSuperclass("Person");
Using the newClassMetadata construction would enforce the rule that a class can
be a member of only one package, so you can neither forget to assign the class
to a package nor add the class to more than one package.
If you want to enforce setting the required metadata, the newXXX could do this,
e.g. for sequence metadata, the name and strategy are required:
packageMetadata.newSequence("SQ1244", SequenceStrategy.CONTIGUOUS);
But most metadata is optional with reasonable defaults.
For boolean properties, you might use Boolean as parameters/return values
instead. Java 5 will automatically convert the setXXX parameters for you, but
the getXXX will return a tristate value which is needed to distinguish between
the user setting a value and not. A boolean return type doesn't allow this.
Finally, note that in the javax.jdo.annotations package we already have enums
for the metadata. So there's no need to repeat them. The only awkward thing is
that they would be referenced from the metadata package. But repeating their
definitions in multiple packages seems worse.
> MetaData specification API
> --------------------------
>
> Key: JDO-615
> URL: https://issues.apache.org/jira/browse/JDO-615
> Project: JDO
> Issue Type: New Feature
> Reporter: Andy Jefferson
> Fix For: JDO 2 maintenance release 3
>
> Attachments: jdometadata-3.patch
>
>
> We can specify MetaData via XML or annotations. The only way missing is via
> an API. I propose mirroring the XML structure with interfaces of the form
> public interface MetaData
> {
> addExtension(String key, String value);
> removeExtension(String key, String value);
> ...
> }
> public interface FileMetaData
> {
> addPackage(PackageMetaData pmd);
> ...
> }
> public interface PackageMetaData
> {
> addClass(ClassMetaData cmd)
> ...
> }
> public interface ClassMetaData
> {
> addField(FieldMetaData fmd)
> ...
> }
> public interface FieldMetaData
> {
> setInheritance(InheritanceMetaData inhmd)
> ...
> }
> and so on.
> We would then require a method on the PMF to register the metadata.
> If there are no objections to such a feature I'll propose a patch to try to
> provide all current JDO2 capabilities.
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