It defines the mapping between the name client uses ( /org.apache.jserv.JServ ) and the actual
servlet class (org.apache.tomcat.servlets.StatusServlet )
<servlet-name> tag : You will use the name (status in your case) defined here within other parts of the DD
So when a request comes in,
1.the container finds <url-pattern> that has /org.apache.jserv.JServ.
2.then container gets the <servlet-name> ( status )
3.container looks in the <servlet> tag for <servlet-name> ( status )
4. then it uses the actual <servlet-class>
hope this helps