I hope someone can help me out on this forum. In the simplest terms I am trying to process orders from a website that uses Zen Cart through an API that receives orders over HTTPS using XML as the data format.

The API I have to use (unfortunately) is from Datapak Services Corporation. It is called the Datapak Services Order Submission API.

I'm thinking the easiest thing for me would be to use an existing Zen Cart payment module from a competing API that also receives the order data in XML, which I can then modify to interface with the Datapak API. Otherwise, I'll have to write the module myself from the ground up, which I really don't want to have to do.

Do any of you know of an existing payment module that generates XML-based order data?

Maybe there is already a Datapak module out there and I don't even know about it. If you do, please let me know.

Or, is there a tutorial on how to build your own payment module for Zen Cart that interfaces with an API that accepts order data in XML format?