This study attempts to enhance the responsiveness of enterprises by adjusting the delivery dates taking into account of the production and delivery schedules in a supply chain. To enhance responsiveness, we suggest a due-date assignment method and re-negotiation process for a sales order processing system. The due-date assignment method is designed with the concept of categorized customers' priorities and the re-negotiation process is designed with the concept of the partial delivery and due-date delay allowances. Usually, the due-dates have been considered as customer-assigned exogenous parameters or fixed endogenous variables set by manufacturers. However, those are customary in some industries, e.g. semi-conductor manufacturing, that customers often request changes for their delivery dates after placing an order if something unexpected happens. From these observations, we also propose a new architecture of responsive sales order processing system based on Web Services and Ubiquitous Computing technologies for reliable real-time information.