Abstract: A system that facilitates the coupling of a plurality of clients to one or more merchants utilizing a network to conduct commerce over the network is disclosed. When a client initiates a connection with a merchant, the merchant responds to the request for connection by transmitting one or more messages back to the client to determine a particular payment processing which entails determining a suitable payment instrument, a payment protocol and standard message formats for conducting the electronic commerce. The payment protocol comprises a message format, a protocol associated with the message format and a weight associated with each of the items associated with the payment processing. The weight is provided by both the client and the merchant to facilitate dynamic negotiation of a mutually acceptable payment processing. The negotiation results in the exchange of standard message formats that the client and the merchant are equipped to process efficiently and securely.