XML returning information.

Hope someone can help out.

        Lets say that a user receives information from a web server.  This information is presented to him via XML-XSL.  The value of the XML treeinformation is modified by the user trough a script (_javascript_ calling the DOM).  My question is how do you send the modified information back to the web server or is XML only for presenting information.  In HTML you use submit that communicates to a Servlet on a web server but I'm not sure what approach to use (if any)  when it comes to XML.

Thanks.