Yusuf Rajkotwala,
ecommerce calls the payment-gateway procedures using service-contract[1] methods from this file:
service0/packages/ecommerce/tcl/ecommerce-credit-procs.tcl
The payment-gateway is a service that forwards calls to a specific payment gateway package, such as authorize-gateway[2].
1. https://openacs.org/doc/current/acs-service-contract/
2. https://openacs.org/doc/current/authorize-gateway/
