Developing a new module

[JuanIgnacio]

I'm devolping a payment module for a local payment gateway.

 

The thing is I need to format the information sent to it.

 

I looked at Paypal's module and I've found that when you click the "confirm" button you are redirected to paypals site.

 

I have to do that, but how do I send order ids to my gateway without going trough checkout_process.php? Before seeing paypal's module i thought that the order id number was generated at checkout_process.php not checkout_confirmation.php

 

Any ideas?