How to write IPTC metadata to files without opening the file?

Question

HI,
I'm trying to run a script (preferably in JS) that allows me to write metadata to a file. I can acheive this very easily by opening the file, but I'd need to batch process many large images, so opening them would cause severe slowness. The purpose of adding the metadata to the files is to search upon them in Bridge.
We're using CS5, but have CS6 if it's better to use.
My Script
// set current doc ref
var docRef = app.activeDocument;
// Set caption in active document
docRef.info.caption = "Some Meta-Data";
Do I need to use bridge to write the metadata without opening the file? Or can running the script in PS allow me to do so?
Thanks,
Tom

Answer 1

Its easy if you use XMP metadata.
app.activeDocument.info.caption (in photoshop script metadata)
and it is the same field as:
     Dublin Core namespace
     namespace:     http://purl.org/dc/elements/1.1/
     Property:          description
you change description on XMP = you are changing the same image.info.caption
Your answer is here:
http://forums.adobe.com/message/5743730#5743730