Need php script/app that outputs an xml file

i need pretty much what the title says.
it should work as a very very simple cms, only without an interface (i’ll make that), but instead just receive POST input and output XML.

example of an output xml:
<thumb src="/>
<photo src=""/>

in flash i’ll do a page that views all items, adds/removes them, each one will have an edit button that will lead to an edit page. i can send every detail in POST, and that’s all i can do.

i dont know how to evaluate this work and i can pay very little, if anyone’s anyway interested PM me please.

PS if this is very simple and someone can post an example php, that’d be very cool