An order handling process starts when an order is received. The order is first registered. If the current date is not a working day, the process waits until the following working day before proceeding. Otherwise, an availability check is performed and a purchase order response is sent back to the customer. If none of the items is available, any processing related to the order must be stopped. Thereafter, the client needs to be notified that the purchase order cannot be further processed. Anytime during the process, the customer may send a purchase order cancel request. When such a request is received, the purchase order handling process is interrupted and the cancelation is processed. The customer may also send a "Customer address change request" during the order handling process. When such a request is received, it is just registered without further action.