Hi diptisk,
Contact payment providers such as UC Group, Paypal, SecureTrading, WorldPay, Google Checkout and so on. Each payment provider will give you details on how to integrate your shopping cart with their credit card processing facilities, and details on how much they charge per transaction.
Warning: Google charge 1.5% per transaction - the most competitive in the marketplace - without
any monthly fees, and they offer incentives when you use AdWords side-by-side.
However, you are
not allowed to save your customer's details to your shop database - you can only use their details for the processing of the order in question.
Paypal is a name that people trust when buying online, but you are stuck with PP branding all over your site.
I haven't used ST as yet but plan on doing so, Their prices look competitive and you get a fairly wide choice of branding.
From a code perspective, most providers use XMLPay (or a variation on it) to receive order and credit card details through an XML document or string and return an XML response.
There are generally two ways of processing transactions:
- Send the order details (amount, shipping, but not card details) to the payment provider's SSL server (your logo, colours and branding are normally optional so the consumer feels comfortable).
The customer puts their card details in, the payment gets processed.
The payment gateway sends a callback to a URL that you specify, in a format you specify (can be name-value pairs - NVPs - or an XML document/string). Your page at your specified URL then does post-transaction processing (like deducting stock from stock levels etc.); - You install an SSL certificate on your server, and take the customer's card details there. You send the full transaction details (card details included) to the payment gateway using HTTP and get a resposne via HTTP. You parse this response to determine the outcome of the card transaction (successful, declined etc.).
I tend to opt for both implementation methods - that way you can analyse customer confidence and behaviour on your site (people tend to trust your company and brand more, if they put details in in your server, rather than going through Paypal or Worldpay).
Hope this helps!
medicineworker