I need a payment gateway for PayPal Adaptive Payments, specifically Chained Payments. I have not yet selected a commerce plugin, but I am leaning toward MarketPress or Woocommerce. I can go with other packages if they are easier to write code for.
The standard PayPal gateway that comes with the commerce plugins is not enough, we must have the added functionality of Chained Payments. This should be written as a plugin, separate from the commerce plugin, so future upgrades to the commerce plugin do not disable the custom payment gateway.
PayPal has extensive documentation and an SDK for Adaptive Payments on their developer sandbox website.