How might I create a function that converts between FullForm and a XML structuce?

Ultimately I'm ideally looking to use CSS and JS to edited the XML structure.

For example using jquery I might do something like $('Times Power').

Ideally I'm looking for the following code to export the following xml.

Times[Rational[1, 2], "test"] 

to

<Times> <Rational> <Number>1</Number> <Number>2</Number> </Rational> <String>test</String> <\Times>