Generating HTML forms from JSON or XML feed using JQuery

Question

I would like to create an HTML form based on XML or JSON data using Jquery and I also plan to validate any form fields that may be empty or incorrect.

I would like to know if there are any other programs/functions that generate such a form dynamically on the fly and the best way to go about implementing this. Any jquery widgets or libraries that work best with workings examples would be much appreciated

And also what feed to best use in this scenario XML or JSON and explain why?

Thanks