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From "Andy Jefferson (JIRA)" <j...@apache.org>
Subject [jira] Commented: (JDO-615) MetaData specification API
Date Mon, 01 Dec 2008 11:05:45 GMT

    [ https://issues.apache.org/jira/browse/JDO-615?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12651966#action_12651966
] 

Andy Jefferson commented on JDO-615:
------------------------------------

To demonstrate a typical use-case for this API, have a look at this :-
http://www.jpox.org/servlet/wiki/pages/viewpage.action?pageId=6619188
This demonstrates the dynamic generation of a class in memory. We then create MetaData for
it (DataNucleus API in this case). We then enhance the in-memory class. We finally use the
in-memory enhanced class (and metadata) at runtime.

JDO-591 will standardise the enhancer API, and JDO-615 will standardise the MetaData API,
hence going a long way towards providing the full process without touching a particular vendors
classes.

> 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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