JARs visible only inside the container ( tomcat ), but not in the 
web applications.

Tomcat uses a hierarchy of class loaders:

          parent 
  (application embeding tomcat - 
  visible in container and web apps)
           |
           |
         common 
     ( files in lib/common - 
  visible in container and web apps)
   |			       |
   |			       |
container		     shared
( files in lib )	       |
(XXX move to		       |
lib/container)		    webapps