OpenJPA enhancement in classloader

[Simone Gianni <si...@apache.org>]

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
http://www.simonegianni.it/
CEO Semeru s.r.l.
Apache Committer

Re: OpenJPA enhancement in classloader

[Simone Gianni <si...@apache.org>]

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.

Simone

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
>> http://www.simonegianni.it/
>> CEO Semeru s.r.l.
>> Apache Committer
>>
>
> --Patrick Linskey
> 202 669 5907
>


-- 
Simone Gianni
http://www.simonegianni.it/
CEO Semeru s.r.l.
Apache Committer

Re: OpenJPA enhancement in classloader

[Patrick Linskey <pl...@gmail.com>]

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
> http://www.simonegianni.it/
> CEO Semeru s.r.l.
> Apache Committer
>

-- 
Patrick Linskey
202 669 5907