[ic] Paysystems Payment Gateway

[Cameron]

I'm currently setting up automated cc billing through Paysytems.com's
merchant gateway, and from what i've found on the mailing lists etc, noone
has bothered having a crack at this before. It all looks fairly simple to
me, it's just your usual POST with hidden fields you pass to the site that
direct you to the appropriate pages on success, failure, etc. It also
returns some data to you.

My question is: is there any documentation out there on exactly how the
whole checkout process works, and how the payment modules are installed and
how they change the checkout procedure? I understand that on my checkout
page, instead of the usual interchangey stuff, i'll direct it off to the
payment gateway, but what would i set as a value for the "success" page? how
would i ensure the order was added to the db?

Basically, i'm fumbling in the dark on this a little, i was hoping to simply
pull a hack job on someone else's module (hence assuring the order goes in
the db, etc), but none of the ones i've seen modules for seem to act all
that close to paysystem.com's methodolgy, insofar as they don't seem to use
a "success" or "failure" URL. I can provide documentation on their service,
should anyone be interested enough to flick through it...