Guys, How would I do this?

I'm really not sure how this is done, so I'm asking for help.

h**p://www.wiigamereviews.co.uk/default.aspx

there's another one here:

h**p://www.wii-consoles.co.uk/wii_console_realtime.asp

They have a live stock updater which scans numerous online shops that sell the console, and then as soon as one of those sites gets some in stock, an alert pops up on the wiigamereview website.

How is it done? Content extraction, screen scraping, access to a vendor specific API...?? I realise they're ASP pages, but would it be possible to do using PHP?

I'm all ears. (Well, obviously not all ears, as that would be pretty disturbing).:)

cheers in advance.
Nick

i would use a PHP's curl functions to the read the other sites online, but they are probably using a developer API or perhaps they are all part of a larger company that shares it info between outlets.