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Posted to jdo-dev@db.apache.org by "Andy Jefferson (JIRA)" <ji...@apache.org> on 2011/08/29 15:11:37 UTC

[jira] [Commented] (JDO-683) Allow version field/property to be visible to application

    [ https://issues.apache.org/jira/browse/JDO-683?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13092825#comment-13092825 ] 

Andy Jefferson commented on JDO-683:
------------------------------------

Or you simply allow @Version to be specifiable on the field/property, and <version> be specified under <field>/<property>

> Allow version field/property to be visible to application
> ---------------------------------------------------------
>
>                 Key: JDO-683
>                 URL: https://issues.apache.org/jira/browse/JDO-683
>             Project: JDO
>          Issue Type: Improvement
>          Components: api
>    Affects Versions: JDO 3 maintenance release 1
>            Reporter: Matthew T. Adams
>              Labels: jdo, jdouserexception, optimistic, transactions, version
>
> Currently, it requires a vendor extension to make the version attribute (field or property) of a PC visible to the application.  Some knowledgeable applications may need not only read access to the version field, but also write access to it.
> I propose that we allow version metadata to specify that a version attribute be application-visible.  For annotation-based metadata, I recommend that it be allowed to be placed on fields & methods.  For XML metadata, add XML attributes "attribute-name" to the "version" element that allows the user to specify which field or property is to hold the application-visible version value.
> Along with this change would be verbiage in the spec noting that applications really shouldn't change this value, but a knowledgeable application may change it, based on a new PMF & PM property called something like "javax.jdo.option.OnVersionChangeByApplication" with the following specified values.
> THROW:  (default) the implementation will throw JDOUserVersionChangeException (extends JDOUserException) as early as the time the value is set, at the next flush, or at commit.
> IGNORE:  the implementation ignores the value the user set for the object's version
> ALLOW:  the implementation allows and uses the value the user set for the object's version
> This allows users to who know how their implementation behaves on user-modified version values to take advantage of such behavior.
> All names proposed are up for discussion.

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