A number of configuration files must be "on the application server classpath". Depending on the application server you're using, this may be one of a number of locations.

Tomcat 5

CATALINA_HOME/shared/classes

Tomcat 6

CATALINA_HOME/lib

This directory is on the "common" classloader path. Resources placed here will be seen by Tomcat internal classes as well as by all applications running in that instance of Tomcat. Using the Shared loader classpath may be preferred (see below).

JBoss

TBD

Variations on Tomcat configuration

Common vs. Shared classloader

Using the "shared" classloader may be preferred, as this does not expose resources to internal Tomcat libraries. The file catalina.properties in the conf dir of CATALINA_HOME can be customized to refer to /shared/classes. Change the following line:

shared.loader=

to

shared.loader=${catalina.home}/shared/classes,${catalina.home}/shared/classes/*.jar

Resources and .jar files can then be placed in the same location as used for Tomcat 5, CATALINA_HOME/shared/classes.