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From "Jason Warner" <jaw...@gmail.com>
Subject Re: An idea for defining custom valves in config.xml
Date Mon, 06 Oct 2008 14:22:12 GMT
On Fri, Oct 3, 2008 at 6:55 PM, David Jencks <david_jencks@yahoo.com> wrote:

>
> On Oct 3, 2008, at 12:51 PM, Jason Warner wrote:
>
>   Hey all.  I'm working on an idea for allowing custom valves to be defined
> in config.xml.  Currently this isn't possible since the tomcat classloader
> would not contain the custom classes for the valve.  I've create a jira for
> tracking this issue [1] and it contains a few links to workarounds.  IMHO,
> The solution we should be looking for is a way to add classes to a module
> without having to undeploy, modify the module config, and redeploying.
>
>
> People have suggested stuff like this before.  IMO it pretty much goes
> against the fundamental idea of geronimo of having fairly fixed plugins with
> only a few knobs to turn to adjust things in config.xml and
> config-substitutions.properties.
>
> Why is changing the classloader contents in config.xml a good idea?  What
> is so hard about redeploying the app if you want to change its classloader
> significantly?  If you want to change a class in the app you have to
> redeploy it.... why is this situation different?
>

The specific instance I have in mind for this change is using a custom valve
for tomcat, so I think the scope really should be limited to just the tomcat
module.  I can't think of another instance where this would be useful, so
it's probably not necessary or desirable to expand it further.  I believe
this situation is different because the structure of geronimo is causing a
disconnect between the functionality of tomcat and the functionality of
tomcat as it is embedded in geronimo.  As Don just said in the middle of my
typing this, I don't believe we should expect the average user to have to
rebuild one of our modules to add something that can be added in a much
simpler way within tomcat itself.

Thanks!

>
> thanks
> david jencks
>
>
> I think this can be done by allowing a user to indicate jars that should be
> loaded by a module within the config.xml.  These jars can then be added to
> the module's classloader for use by the module.  I'm not extremely familiar
> with how our classloader works, but I've taken a look through the code and I
> think the ability to add to the classloader can be implemented without too
> much difficulty.  I'm not quite sure what type of scope to give this change,
> though.  Should I leave it as a change aimed solely at tomcat valves or
> should it be expanded to encompass any configuration?  I realize this is
> only a rough idea of what i plan to do, but I'm still working out the
> details of how to proceed.  I'm hoping for some feedback on what I intend to
> do and possibly some alternate ideas if anyone has some.
>
> Thanks!
>
>
> [1]  https://issues.apache.org/jira/browse/GERONIMO-4335
>
> --
> ~Jason Warner
>
>
>


-- 
~Jason Warner

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