What is a supermarket checkout system?

All these processes are very helpful for the purposes of dealing with an individual customer's purchases. However, when computers are linked in a network, many new uses are possible.

Now, I am going to draw a different system boundary. The components of this supermarket checkout system are the checkout terminal, the network and the database server. A database server is used to make the data in databases available to other computers on the network, and therefore to users. You met a specialised form of database server in Section 14.2: the FirstClass server. In the following sections, I'll focus on the network first and then look at the database server.

You might be wondering about the users of the system: the customer and the checkout operator. For the time being, we are focusing on the computers and network, rather than thinking about the end users.