i am looking for online resources or a book covering e-payment/billing systems and especially debit-card,credit-card, paypal providers.
and how to approach an implementation of respective connectors which handle transactions with these providers.
i searched quite a lot at amazon or google but could not find any resources giving me good information (which is quite surprising). all of them were more focused on the business and security point of view.
if somebody could point me out to the right book or online tracks i would be glad