This is a very simple example of using XML for load and submit of data with an Ext dynamic form. For a similar example using JSON rather than XML, see the JSON Form example.
Click "Load" to load the dummy XML data from the server using an XmlReader.
After loading the form, you will be able to hit submit. The submit action will make a post to the server, and the dummy XML file on the server with test server-side validation failure messages will be sent back. Those messages will be applied to the appropriate fields in the form.
The js is not minified so it is readable. See xml-form.js.