Many Apache webserver installations use uriworkermap to configure requests are forwarded to Tomcat/JBoss and which are not.   This provides a certain level of security.  For example:

## APACHE RESOURCES (static files):
!/*.gif=myapp
!/*.html=myapp

## DISALLOW  (security-related filter):
!/*.jsp=myapp
!/*.xml=myapp

## TOMCAT RESOURCES:
/*.do=myapp

However if you dynamically generate your sitemap.xml or any other XML files using a servlet then this security will be a problem since the XML request will not make it to Tomcat/JBoss.  This is when mod_rewrite comes to the rescue.

You can set up mod_rewrite to rewrite the sitemap.xml request to be a sitemap.do request.

RewriteRule ^/sitemap\.xml$ /sitemap.do [PT,L]

Then you can set up Struts to forward this request to sitemap.xml.

<action path="/sitemap" forward="/sitemap.xml"/>