The standard solution for your problem  is
webservices,but if you need a simple solution that
needs less trainig than using web services that is
below:

you should do a HTTP request through java network API
in your servlet  and then get the content and pars it
through JAXP parsers which is included in J2EE.

please mention that using requestdispatcher just
forward the request and response objects to another
jsp and you can't access  the content (XML in your
case)
in your sevlet and the content will be sent to
browser.

I saw that their are 3 emails up to now that tried to
answer your question I think that all of them help you
to understand my solution.