I have been coding a payment gateway using a company called SwipeHQ. Using their APIs I have programatically created products from my website and make sure they stay updated. However, I'm now completely stuck about how to have my checkout navigate to their payment form and then return back.
The flow diagramme would look something like this:
My Website Checkout -> update product details on SwipeHQ -> redirect to SwipeHQ payment form -> (success) navigate back to cart -> update stock / tidy things up -> redirect to thank you page.
I have tried using something like
header("Location: https://payment.swipehq.com/?identifier_id=" . $transactionId); but this just gives me an error message.
Could someone let me know vaguley what the correct protocol is for doing something like this?