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From "Lee, William" <William....@Cognos.COM>
Subject RE: Webapp classloader question.
Date Thu, 09 Oct 2003 20:53:46 GMT
This won't work since, all jar files in commons/lib, commons/endorsed, and
commons/classes are all visible to the tomcat's "commons" classloader. So,
there is no difference whether we put the xerces jar files in "lib" or
"endorsed", the one from webapps will be skipped.

I think the question boiled down to, if we have Xerces on both "endorsed"
and "webapps", which one should be used? For tomcat, I would thought that
the order for class searching will be "webapps", "shared", "commons"
(including "endorsed"), then "system".

I believed tomcat put "endorsed" before "system" is to follows the "endorsed
classloading spec.". But I also believed forcing delegate model for xerces
and xalan maybe overkill?

Indeed, the tomcat's "class-loader-howto" document also indicated that the
one from webapps should be used instead.

Frankly speaking, I'm no expert on these topics, so please feel free to
correct me if I mis-understanding anything here.

Thanks.
William.

-----Original Message-----
From: Shapira, Yoav [mailto:Yoav.Shapira@mpi.com] 
Sent: Thursday, October 09, 2003 12:44 PM
To: Tomcat Developers List
Subject: RE: Webapp classloader question.



Howdy,
Tomcat 4.1.x implements the endorsed classloader spec.  It's compliant with
the Servlet Specification v2.3.  What you can do if you want your webapp to
use the latest xerces/JAXP, is:
- Move $CATALINA_HOME/common/endorsed/* to $CATALINA_HOME/common/lib
- Put your later xerces etc. in WEB-INF/lib as you've been doing.

Yoav Shapira
Millennium ChemInformatics


>-----Original Message-----
>From: Lee, William [mailto:William.Lee@Cognos.COM]
>Sent: Thursday, October 09, 2003 12:38 PM
>To: tomcat-dev@jakarta.apache.org
>Subject: Webapp classloader question.
>
>
>Hi all,
>
>I'm not sure if this message reaches you guys yet, so here it go again. 
>Sorry for any inconvenience if you receiving this message twice.
>
>Thanks.
>William.
>
>-----Original Message-----
>From: Lee, William [mailto:William.Lee@cognos.com]
>Sent: Tuesday, October 07, 2003 3:55 PM
>To: 'tomcat-dev@jakarta.apache.org'
>Subject: Webapp classloader question.
>
>
>Hi all,
>
>When moving from tomcat 4.0.x to 4.1.x, we discovered that the 
>WebappClassLoader.java had been changed such that all classes from 
>"org.apache.xerces" and "org.apache.xalan" are forced to be loaded
using
>the
>delegate model first, before looking into the webapp directory. This
seems
>to related to the JDK 1.4 support of the xml and xslt parser.
>
>However, after a long conversation with the Sun's Java engineer, he
point
>out that, even JDK 1.4 shipped with the default xml and xslt parser, 
>application server and servlet container should continue to use the one 
>provided from the webapp directory as described in the servlet spec.
2.3.
>
>Could someone please hint some lights on why tomcat 4.1.x decided to 
>enforce the delegate model for these two packages?
>
>(The reason I'm asking is that, we try to use the latest Xerces in our 
>webapps, and since it always look and found the one from
common/endorsed
>directory, our latest version will always be skipped.)
>
>Thanks in advance for your help.
>William.
>
>Join us at Cognos' biggest event of the year Enterprise 2003, The
Cognos
>Business Forum.  Taking place in over 25 cities around the world, it's
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Join us at Cognos' biggest event of the year Enterprise 2003, The Cognos
Business Forum.  Taking place in over 25 cities around the world, it's an
opportunity for Business and IT leaders to learn about strategies for
driving performance. Visit http://www.cognos.com/enterprise03 for more
details. 

This message may contain privileged and/or confidential information.  If you
have received this e-mail in error or are not the intended recipient, you
may not use, copy, disseminate or distribute it; do not open any
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