I'm writing my own payment module for OSCommerce. We use asynchronous callbacks from our payment gateway. It means that I need to create the order while handling such a callback. I understand that I should use checkout_process.php for that. But the problem is that there's no session context since the callback is asynchronous. So tep_session_is_registered will fail. From the code of other payment modules it looks like mostly they are based on the existing session context.
So what's the best strategy in that case?
In fact, the idea is that we have all the necessary information returned in the data with the callback. So in theory I can create a new order out of the session context, but I don't want to rewrite the already existing logic and it has a lot of dependencies. On the other hand, I can try to restore the session from the database (create a kind of dummy session with the necessary context to call checkout_process.php), but that doesn't seem easy at the moment. Nor does it seem the right thing to do.
Maybe some plugins use the same pattern?
Thanks