Because the there may be serveral class loaders associated with a
deployment. I'm missing the exact context of this discussion and how it
correlates with the entity manager spi. Has there been a definition of
what the tcl must be for the entity manager spi lifecycle? I don't see
it browsing through the current ejb3 spec.
-----Original Message-----
From: Max Andersen
Sent: Thursday, February 02, 2006 3:09 PM
To: Scott M Stark; Emmanuel Bernard; Bill Burke
Cc: Hibernate development
Subject: Re: [Hibernate] ClassLoader injection
hi,
Why is the tcl not the right one even when generating classes ?
if we don't use the same how can you have consistent resource loading,
annotation searching and code invocation ?
/max
> The general problem is that the thread context class loader can be too
> generic when you have a mesh of class loaders. As is mentioned in
latter
> replies in this thread, if classes from a given package namespace have
> already been loaded via one class loader, generally all subsequent
> classes in the same package should be loaded/defined using the same
> class loader. Not doing so will lead to security and type consistency
> problems.
>
> In the case of the ejb3 entity manager spi, it does make sense that
you
> would ask it for the correct class loader for byte code manipulation
vs
> a class loader to query for resources and do annotation searching.
>
> -----Original Message-----
> From: Max Andersen
> Sent: Tuesday, January 31, 2006 11:53 PM
> To: Emmanuel Bernard; Bill Burke
> Cc: Hibernate development; Scott M Stark
> Subject: Re: [Hibernate] ClassLoader injection
>
> Hi,
>
> to bill, yes I know ctx current thread is the only way, that was my
> whole
> point (using ctx current thread in
> hibernate was actually the first patch i provided to hibernate core ;)
>
> and yes, having a third classloader concept in the spec sounds like a
> very
> broken thing.
> I would love to hear why it is needed.
>
> /max
>
>> The RI team is going to creak, but I'm inclined to remove it as well.
>>
>> AS for your first remark, what's wrong with doing getResource with
the
>
>> regular classloader? I don't get it.
>>
>>
>> Bill Burke wrote:
>>> I understand the need for PUInfo.getNewTempClassLoader() as
>>> getResource("META-INF/persistence.xml") may/will return multiples.
>>> Also, you may want to introspect the class for annotations before
you
>
>>> decide what needs to be bytecode massaged.
>>>
>>> As for getClassLoader()? I'm not sure of the reasoning. I know
> Scott
>>> has some spec input on this. Maybe we should get it removed?
>>>
>>> Emmanuel Bernard wrote:
>>>> Year I'm aware of that Bill :-)
>>>> But in this case, and like Max said, why on earth the
>>>> PersistenceUnitInfo has a getClassLoader() method instead of using
> the
>>>> context CL?
>>>>
>>>>
>>>> Bill Burke wrote:
>>>>
>>>>>
>>>>>
>>>>> Max Rydahl Andersen wrote:
>>>>>
>>>>>> If it is for the spec then I would argue that the spec is very
> wrong
>>>>>> since it will
>>>>>> break all other kind of stuff. Like how will you convince all the
>
>>>>>> external libraries hibernate
>>>>>> uses to use your "magic" classloader ? (e.g. log4j, dom4j, cglib,
>
>>>>>> yada, yada)
>>>>>>
>>>>>
>>>>> Thread.getContextCL() is the only way. If a library doesn't use
>>>>> Thread.getCCL() then it is a poorly written library. App server
> and
>>>>> J2EE in general require this because of classloader isolation
> (scoped
>>>>> ears or wars). If you are within Hibernate code and call
>>>>> Class.forName() it will use the classloader that loaded Hibernate
> to
>>>>> load the class. (read the javadocs) and you could get CCE, CNF
>>>>> exceptions. If you already know this, then apologies.
>>>>>
>>>>> The same issues effect the loading of resources.
>>>>>
>>>>> Bill
>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>
>
>
--
--
Max Rydahl Andersen
callto://max.rydahl.andersen
Hibernate
[EMAIL PROTECTED]
http://hibernate.org
JBoss Inc
[EMAIL PROTECTED]
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