Internet Open Trading Protocol is an IETF specification which defines a way to create a trading environment that is more reliable and personal than existing methods by giving the consumer more opportunities to interact directly with all parties of a transaction.
IOTP focuses on the transaction process; therefore, it is application and payment system independent.
IOTP relies on standard "Trading Components" to define and keep track of all the stages of an e-commerce transaction. Parties involved use these Trading Components to send and receive the necessary information (always in XML format) to execute the deal.
Here's an example of how a simple payment-exchange transaction works:
Let's say a consumer shows interest in a merchant's product.
The merchant decides which payment brands (Visa, MasterCard, DigiCash, etc.,), protocols, and currency denominations he will accept. He then sends that info to the consumer using the Brand List Component.
The consumer makes his choices and sends them back to the merchant using a Brand Selection Component.
The merchant creates a Payment Component that details the payment selection and provides payment directions. He also creates an Organization Component that recognizes the payment handler and merchant roles.
The consumer checks the information, then uses the Status Component to let the payment handler know the deal is good to go.
The payment handler checks the information. If everything looks legit, he swaps Payment Scheme Components for payment brand and payment protocol.
Finally, receipt is delivered to the consumer via the Payment Receipt Component.
As transactions become more complex and involve more players, the need for more Trading Components becomes necessary.