A technique for effecting electronic commerce using a data network is described. The data network includes a plurality of subsystems which, together, form an integrated system for receiving customer orders for selected items via a data network, fulfilling the customer orders, and delivering the ordered products to the customers. Moreover, according to a specific embodiment, the integrated nature of the system architecture of the present invention allows the on-line merchant to provide a guarantee to the customer that the ordered items will be available to be delivered to the customer at the specified delivery date, time, and location.