1. A method, comprising the steps of: maintaining a fulfillment network model in at least one server, the fulfillment network model comprising an abstraction of a physical fulfillment network operated by a merchant, the physical fulfillment network being configured for multi-channel delivery; storing inventory data received from the merchant in the at least one server, the inventory data indicating amounts of a plurality of inventory items stored in the physical fulfillment network; maintaining an e-commerce application for the merchant on the at least one server; generating an order for at least one of the inventory items in the e-commerce application based upon interaction with a client; and generating a fulfillment manifest based upon the fulfillment network model, the fulfillment manifest identifying an optimal one of a plurality of fulfillment scenarios to be implemented in the physical fulfillment network to implement fulfillment of the order, wherein the fulfillment scenarios incorporate a preparation time for preparing the at least one of the inventory items for dispatch, wherein the preparation time further comprises a pick-to-manifest time and an internal transportation time, wherein the pick-to-manifest time is a period of time needed to pick the at least one of the inventory items from the inventory and ready the at least one of the inventory items for shipment, wherein the internal transportation time is based at least in part on a transportation schedule for a plurality of vehicles to transport the at least one of the inventory items between a plurality of sites in the physical fulfillment network, wherein the fulfillment manifest is generated based in part upon a delivery capability of respective ones of the plurality of sites in the physical fulfillment network from the fulfillment network model, wherein the delivery capability is chosen from options of: limited to delivering to another site in the physical fulfillment network; limited to delivering the at least one of the inventory items to a physical store; and unlimited.