Classpath and DataSource within Tomcat

Question

Used software:
- Tomcat 5.5.11
- JDK 5.0
- Windows XP SP2
Problem statement:
I have a webapplication, called monitorclient, which uses a connection
to a database using a JNDI bound DataSource object through my context.xml file.
To connect to the database (SQL Server), I need several JAR files. Whenever I
place these JAR files inside the ${CATALINA_HOME}/common/lib directory,
everything seems to work fine.
However, I would like to place these JARs into my webapp's lib directory, which is:
${CATALINA_HOME}/webapps/monitorclient/WEB-INF/lib/Whenever I do this, the driver class ...
com.microsoft.jdbc.sqlserver.SQLServerDriver... seems to fail to be found.
The generated exception is:
javax.servlet.jsp.JspException: Unable to get connection, DataSource invalid:
  "org.apache.tomcat.dbcp.dbcp.SQLNestedException:
    Cannot load JDBC driver class 'com.microsoft.jdbc.sqlserver.SQLServerDriver'".I've read the Tomcat documentation about classloading, and I can't seem to find
any errors from my part. I queried the forums and google about this matter but
I don't seem to get any results.
Directory structure:
${CATALINA_HOME}
  /webapps/
    /monitorclient/
       /META-INF/
          context.xml -> has the DataSource
       /WEB-INF
          /classes/
            /com/.../[some java code]
          /lib/
            msbase.jar       --> when I place these jars here instead of in
            mssqlserver.jar      ${CATALINA_HOME}/commons/lib, classloading
            msutil.jar           seems to fail.
     index.jsp
     blah.jsp
     [...].jspAny help, pointers or the like are greatly appreciated.

Answer 1

We had a discussion about this a little while ago.
http://forum.java.sun.com/thread.jspa?threadID=651804
Coming back to it, I have finally made some time to do that testing I promised. For me it only works when the driver is in /common/lib.
I have tested this on both Tomcat 4.1.30 and Tomcat 5.0.28
That makes sense to me, as it is Tomcat being responsible for loading the datasource, the driver needs to be available to the Tomcat internal classes.
I think this page spells it out rather clearly:
http://jakarta.apache.org/tomcat/tomcat-5.0-doc/jndi-datasource-examples-howto.html
NOTE: Do not install these jarfiles in your /WEB-INF/lib, or $JAVA_HOME/jre/lib/ext, or anywhere else. You will experience problems if you install them anyplace other than $CATALINA_HOME/common/lib.
Can't get any clearer than that...
Cheers,
evnafets