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From "Kevin Sutter (JIRA)" <j...@apache.org>
Subject [jira] Commented: (OPENJPA-758) OpenJPA doesn't find ValueHandlers with an applicable class loader
Date Mon, 24 Nov 2008 20:07:44 GMT

    [ https://issues.apache.org/jira/browse/OPENJPA-758?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12650305#action_12650305
] 

Kevin Sutter commented on OPENJPA-758:
--------------------------------------

Hi,
Just to ensure that I have discovered the same situation that you experienced, could you validate
the following?

During my recent experimentation with ValueHandlers and FieldStrategies [1], I came across
the situation that you describe in this JIRA.  The classloading in question is in the namedHandler
method on the MappingRepository class:

        name = Configurations.getClassName(name);
        try {
            Class c = JavaTypes.classForName(name, val,
                (ClassLoader) AccessController.doPrivileged(
                    J2DoPrivHelper.getClassLoaderAction(ValueHandler.class)));

I agree that a user-supplied class, such as a ValueHandler, should not depend on the classloader
of the ValueHandler class.  But, I wanted to verify that we're talking about the same area
of the code.

Thanks,
Kevin

[1]  http://n2.nabble.com/ValueHandlers-vs-FieldStrategies-td1573427.html

> OpenJPA doesn't find ValueHandlers with an applicable class loader
> ------------------------------------------------------------------
>
>                 Key: OPENJPA-758
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-758
>             Project: OpenJPA
>          Issue Type: Improvement
>    Affects Versions: 1.0.3
>         Environment: WebSphere 6.1, any other, 1.0.3 and probably all existing others
>            Reporter: Jan Dockx
>            Priority: Blocker
>   Original Estimate: 72h
>  Remaining Estimate: 72h
>
> We are working with ValueHandlers for enterprise applications that   
> will be deployed on WebSphere, currently 6.1.0.19. We believe that the   
> current OpenJPA implementation has made a less than stellar choice in   
> how to load value handlers, and suggest a change
> ValueHandlers are naturally (or so we find) specific for certain value   
> types, that are often dependent on the semantics of your business, and   
> thus are part of the application, in some way bundled in the ear you   
> are deploying. We do unit testing out of the container with OpenJPA   
> 1.0.3, and everything works like a charm. 
> When we deploy on WebSphere however, nothing works. OpenJPA does not   
> find our value handlers. 
> Luckily OpenJPA is open source :-), so we found with certainty that   
> the reason is that OpenJPA tries to load the value handler with the   
> class loader that loaded the meta information for the property. The   
> class of that object is part of OpenJPA, and inside WebSphere, OpenJPA   
> is loaded with a class loader that has no access to the application   
> code, the code in the ear. So, ClassNotFoundException. Bummer. 
> The long term solution, we believe, is not to use the classloader   
> associated with the meta information for the property (i.e., the   
> OpenJPA class loader), but instead the class loader of the entity for   
> which we are working (which is also reachable via the parameters of   
> the method that does the loading). Using the class loader of the   
> actual value we want to handle is not an option, since the value can   
> be null. The entity however is normally also part of the application,   
> the ear, and cannot be null. 

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