The completed system will consist of two distinct programs: the GUI order-entry client and the non-interactive order processing service. Although an SMTP service plays a vital part in the overall system, it will be treated as a black-box component. The “Deployment” section later in this chapter explains the role of the SMTP server and its use.
Before examining the nuts-and-bolts details of the client and server applications, we must spend some time gathering the business requirements behind the system. Before proceeding, it is necessary to answer the following two questions:
Where will the list of items that can be ordered come from?
Exactly what information needs to be collected to complete an order?