How do I declare the web.xml file for Servlets 3.0 and JSP 2.1? (
Tomcat 7, and so on)
How do I declare the web.xml file for Servlets 2.5 and JSP 2.1? (Tomcat 6, and so on)
How do I declare the web.xml file for Servlets 2.4 and JSP 2.0? (Tomcat 5, Resin 3, and so on)
Be sure that you do
not leave a DOCTYPE declaration from a previous version of the Servlets Specification in this file.
Be aware that this is the manner in which the deployment descriptor must be configured in order for the JSP 2.0 EL (Expression Language) to be enabled on JSP pages by standards-compliant containers such as Tomcat.
ServletsFaq JspFaq