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Message-ID: <73a75e430810060722n5c120cc5p48ab3379c123ccb9@mail.gmail.com>
Date: Mon, 6 Oct 2008 10:22:12 -0400
From: "Jason Warner" <jaw981@gmail.com>
To: dev@geronimo.apache.org
Subject: Re: An idea for defining custom valves in config.xml
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	 <8F55CEC0-B313-43F8-8F1A-E9CABB15AF93@yahoo.com>

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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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<div dir="ltr"><br><br><div class="gmail_quote">On Fri, Oct 3, 2008 at 6:55 PM, David Jencks <span dir="ltr">&lt;<a href="mailto:david_jencks@yahoo.com">david_jencks@yahoo.com</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div style=""><br><div><div class="Ih2E3d"><div>On Oct 3, 2008, at 12:51 PM, Jason Warner wrote:</div><br><blockquote type="cite"><div dir="ltr">&nbsp; Hey all.&nbsp; I&#39;m working on an idea for allowing custom valves to be defined in config.xml.&nbsp; Currently this isn&#39;t possible since the tomcat classloader would not contain the custom classes for the valve.&nbsp; I&#39;ve create a jira for tracking this issue [1] and it contains a few links to workarounds.&nbsp; 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.&nbsp;</div>
</blockquote><div><br></div></div><div>People have suggested stuff like this before. &nbsp;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.</div>
<div><br></div><div>Why is changing the classloader contents in config.xml a good idea? &nbsp;What is so hard about redeploying the app if you want to change its classloader significantly? &nbsp;If you want to change a class in the app you have to redeploy it.... why is this situation different?</div>
<div></div></div></div></blockquote><div><br>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.&nbsp; I can&#39;t think of another instance where this would be useful, so it&#39;s probably not necessary or desirable to expand it further.&nbsp; 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.&nbsp; As Don just said in the middle of my typing this, I don&#39;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.&nbsp; <br>
<br>Thanks!<br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div style=""><div><div><br></div><div>thanks</div><div>david jencks</div>
<div class="Ih2E3d"><div><br></div><br><blockquote type="cite"><div dir="ltr"> I think this can be done by allowing a user to indicate jars that should be loaded by a module within the config.xml.&nbsp; These jars can then be added to the module&#39;s classloader for use by the module.&nbsp; I&#39;m not extremely familiar with how our classloader works, but I&#39;ve taken a look through the code and I think the ability to add to the classloader can be implemented without too much difficulty.&nbsp; I&#39;m not quite sure what type of scope to give this change, though.&nbsp; Should I leave it as a change aimed solely at tomcat valves or should it be expanded to encompass any configuration?&nbsp; I realize this is only a rough idea of what i plan to do, but I&#39;m still working out the details of how to proceed.&nbsp; I&#39;m hoping for some feedback on what I intend to do and possibly some alternate ideas if anyone has some.<br>
 <br>Thanks!<br> &nbsp; <br><br>[1]&nbsp; <a href="https://issues.apache.org/jira/browse/GERONIMO-4335" target="_blank">https://issues.apache.org/jira/browse/GERONIMO-4335</a><br clear="all"> <br>-- <br>~Jason Warner<br> </div></blockquote>
</div></div><br></div></blockquote></div><br><br clear="all"><br>-- <br>~Jason Warner<br>
</div>

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