Hi Stephani,
1. Event portal is front-end service, it only shows information from published events, so it could be integrated with any payment gateway.
2. It should be a web page which invokes your own back-end service for payment.
When event pass has been selected and user clicked "Checkout" button, we should send event name, total price and purchase ID to our own back-end endpoint.
So the code would be a web page which is consisted of following elements:
* A form which presents information for payment as final confirmation for user.
* Javascript code which is used for requesting our own payment service URL.
Thus I think the real challenge is back-end code for payment verification.
You could take tutorial on developer.squareup.com as reference:
https://developer.squareup.com/docs/payment-form/payment-form-walkthrough
It includes many useful information to build a Square payment gateway.
* A Node.Js back-end based demo with a HTML front-end page
* You can test Square API in that demo.(It'll connect to Square sandbox environment for test)
* Other language based template
In conclusion, real payment gateway should still be hosted on an external web server, it could be an Azure application.
Regards,
Clofly
