Multiple Tomcat Lib Directories in
Tomcat 5.5.x – Purpose and
differences
Vijay Prasad Gupta
ECM & Web Architect
http://www.linkedin.com/in/vpgupta/
http://ecmwebandmore.blogspot.com/

Multiple lib directories under
Tomcat…why?
• <Catalina_Home>/server/lib
• <Catalina_Home>/common/lib
• <Catalina_Home>/shared/lib

<Catalina_Home>/server/lib
• Contains jar files to be used
by tomcat container.
Includes all classes and
resources required to
implement Tomcat 5.5.x
itself
• These classes and resources
are totally invisible to web
applications
• The Catalina class loader
makes these classes and
resources visible to tomcat
containers

<Catalina_Home>/common/lib
• Contains jar files to be used
by both the tomcat container
as well as all deployed web
applications
• These classes and resources
are visible to both container
and all web applications
• The Common class loader
makes these classes and
resources visible to both
container as well as web-
applications

<Catalina_Home>/shared/lib
• Contains jar files to be used
by all deployed web
applications only
• These classes and resources
are totally invisible to tomcat
container
• The Shared class loader
makes these classes and
resources visible to all
deployed web applications

Summary
Folder Path Visible to tomcat Visible to web Class Loader Name
container applications
<Catalina_Home>/server/lib Yes No Catalina
<Catalina_Home>/common/lib Yes Yes Common
<Catalina_Home>/shared/lib No Yes Shared

References
• http://tomcat.apache.org/tomcat-5.5-
doc/class-loader-howto.html
• http://javahowto.blogspot.com/2007/01
/tomcat-commonlib-vs-sharedlib.html

Thank You !!
• Any Questions ?