Automatized payments

[jaspita]

Hi everybody

Suppose I want to make a website that manages bitcoins from the website users, so each user deposits coins on their accounts. This is as easy as giving each user an offline generated address to deposit. This way, just checking the balance of each address the webmaster could know the balance of each user account.

The problem comes when a user wants to withdrawal bitcoins from his/her account. A way to do that is to load the private key in a client and manually send the coins to the address provided by the user in the withdrawal proccess.

Now, my question: is there any program available in any language (web compatible) to make this withdrawal process automatically? If so (as I suspect there must be), does anybody know where can I find it? Preferably with some kind of guide or tutorial...
I guess all exchanges must use this automatized proccess... Am I wrong?

I'm not a web developer, but I have a web-related project and I would like to make easier the research to my programmer...

Thank you so much in advance!!!

Cheers, jaspita

[grue]

if you want to make sure the inputs are always from a specific customer's address, you'll need the raw transactions api. otherwise, I don't see why you can't just send with a master wallet.