[digester] Re: Classloading regression between commons-digester-1.0 and later versions

[robert burrell donkin <ro...@blueyonder.co.uk>]

hi jan

please remember to add the subject prefix for the component.

On Thu, 2005-09-29 at 13:57 -0700, Jan Luehe wrote:
> This may be an old topic, but it seems a classloading regression was
> introduced between commons-digester-1.0 and later versions (including
> the most recent).

this is indeed a very old topic :)

<snip>

> Can someone explain to me the motivation for setting the
> "useContextClassLoader" property to FALSE by default?

i can offer you nothing more than the logs: it is set to FALSE by
default for no very good reason but most likely since it was felt
(rightly or wrongly) to preserve backwards compatibility.

> We can easily restore the commons-digester-1.0 behaviour in our own
> code by setting "useContextClassLoader" to TRUE on the Digester
> instances we acquire. However, this is not possible on "foreign" code
> that we bundle.
> 
> It would be useful if Digester.getClassLoader() would also consider a
> system property (in addition to its own "useContextClassLoader"
> property) when determining whether to use the context classloader.

+1

can anyone think of any reasons not to add this?

> Any comments appreciated.

submit a patch :)

- robert


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Re: [digester] Re: Classloading regression between commons-digester-1.0 and later versions

[Jan Luehe <Ja...@Sun.COM>]

Hi Robert,

robert burrell donkin wrote On 10/01/05 11:11,:
> hi jan
> 
> please remember to add the subject prefix for the component.

will remember from now on! :)

> On Thu, 2005-09-29 at 13:57 -0700, Jan Luehe wrote:
> 
>>This may be an old topic, but it seems a classloading regression was
>>introduced between commons-digester-1.0 and later versions (including
>>the most recent).
> 
> 
> this is indeed a very old topic :)
> 
> <snip>
> 
>>Can someone explain to me the motivation for setting the
>>"useContextClassLoader" property to FALSE by default?
> 
> 
> i can offer you nothing more than the logs: it is set to FALSE by
> default for no very good reason but most likely since it was felt
> (rightly or wrongly) to preserve backwards compatibility.
> 
> 
>>We can easily restore the commons-digester-1.0 behaviour in our own
>>code by setting "useContextClassLoader" to TRUE on the Digester
>>instances we acquire. However, this is not possible on "foreign" code
>>that we bundle.
>>
>>It would be useful if Digester.getClassLoader() would also consider a
>>system property (in addition to its own "useContextClassLoader"
>>property) when determining whether to use the context classloader.
> 
> 
> +1
> 
> can anyone think of any reasons not to add this?

The only problem with adding a system property for this purpose
is that it would require granting the commons-digester jar the
permission to read it. It a web application bundles commons-digester
locally, it will not have this permission in most cases.

Perhaps it is safer to stick to the current "useContextClassLoader"
property and require that web applications always bundle
commons-digester, in which case the classloader that loaded
Digester.class will correspond to the web application's classloader,
which has access to all classes under WEB-INF/lib[classes].

Thanks,


Jan


> 
>>Any comments appreciated.
> 
> 
> submit a patch :)
> 
> - robert
> 


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