Classloader question in Tomcat 4.1.x

[Wu Yiqun <yq...@mail.etonenet.com>]

Hello:
 I have some web application using commons-digester and common-dbcp. When I upgrade from
tc 4.0->tc 4.1.12, I found there are some jar in common/lib and server/lib. From the Class Loader Howto,
it is assumed following class search order:

/WEB-INF/classes of your web application 
/WEB-INF/lib/*.jar of your web application 
Bootstrap classes of your JVM 
System class loader classses (described above) 
$CATALINA_HOME/common/classes 
$CATALINA_HOME/common/endorsed/*.jar 
$CATALINA_HOME/common/lib/*.jar 
$CATALINA_HOME/shared/classes 
$CATALINA_HOME/shared/lib/*.jar

 Now in common/lib there are commons-collections.jar, commons-dbcp.jar, commons-logging-api.jar,
commons-pool.jar. In server/lib there are commons-beanutils.jar and commons-digester.jar.

 I have tried following method.

1. If in every /WEB-INF/lib has a copy of commons-digester and commons-beanutils.jar, then everything seems OK.

2. If delete all commons-digester and commons-beanutils.jar in /WEB-INF/lib and copy to common/lib, then tomcat
report  java.lang.ClassNotFoundException: org.apache.catalina.core.StandardServer.

3. If delete all commons-digester and commons-beanutils.jar in /WEB-INF/lib and copy to shared/lib according to
 Howto, then tomcat report an user class not found (cause it is created by digester).

4. If move commons-digester, commons-beanutils.jar + emp.jar(a user lib), log4j, jakarta-oro.jar to shared/lib,
then tomcat report strange error java.lang.ClassCastException: etonenet.db.PoolDataSource (a user class)

5. If using $CATALINE_BASE variable, the jar in $CATALINA_HOME/shared/lib is not included, is this a bug or
expected result?

Some background info:
 OS: Redhat 7.3
 JDK: Sun JDK 1.3.1_04
 Servlet Engine: Tomcat 4.1.12 standalone mode
 DB: mysql

 I have 4 webapps, every application uses a common user lib emp.jar(which wrap log4j1.2 and
commons-dbcp + commons-digester).  I want to put those common used jar to a common place instead
of distribute them in every /WEB-INF/lib. Thanks and please give me some hint on this problem.

E-Mail: yqwu@mail.etonenet.com
Http://www.etonenet.com