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From Simone Gianni <>
Subject Re: OpenJPA enhancement in classloader
Date Wed, 23 Jul 2008 12:07:47 GMT
Hi Patrick,
thanks for your answer, just a few minutes ago I found a solution.
Basically I needed two enhancements, both at runtime, and the problem
was a bug in the version of BCEL used by the other enhancer. Sorry for
the noise.

Anyway, I found it rather strange that there is no
PCEnhancerClassLoader, it could be rather useful for a number of basic
setups, for testing for example, while the other automagic/advanced
systems are perfect for more complex setups. I am on Java SUN 1.6.0_03
under linux, and OpenJPA does not manage to auto install its enhancer.
Could you point me to the class that tries to install it? Maybe, since I
am in a quite "strange" environment, there is something not compliant
with what OpenJPA expects.


Patrick Linskey wrote:
> Hi,
> Can you describe the classloader requirements of your environment in a
> bit more detail? In particular, I'm wondering whether or not you can
> just run the app in the classloader that has the transformed classes.
> Does that make sense?
> Also, what JVM are you using?
> -Patrick
> On Jul 21, 2008, at 9:53 AM, Simone Gianni wrote:
>> Hi All,
>> for a number of reasons I cannot explain right now ( :) ), I need to
>> load JPA annotated classes, and enhance them with OpenJPA, from a
>> ClassLoader, and not from an agent or a J2EE environment. I wrote a
>> classloader that calls the PCClassFileTransformer inside the defineClass
>> method, I used the code in the PCEnhancerAgent class to do this, and I
>> see the classes being (properly ?) rewritten.
>> BUT, when the class is then used by OpenJPA, it uses a different
>> OpenJPAConfiguration, which returns a different MetadataFactory
>> (different instance), and an error is raised as if the class was not
>> enhanced.
>> I don't see how to force OpenJPA to use the same configuration/metadata
>> used by the PCClassFileTransformer, and don't even understand if this is
>> somehow a way to proceed or if there is another (maybe simpler and
>> smarter) solution.
>> Got any idea?
>> Thanks in advance,
>> Simone
>> --Simone Gianni
>> CEO Semeru s.r.l.
>> Apache Committer
> --Patrick Linskey
> 202 669 5907

Simone Gianni
CEO Semeru s.r.l.
Apache Committer

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