■ Disconnect: at the end of his or her shift, the employee disconnects from
the central server, thus deactivating the counter terminal and returning it
to the initial state. The terminal is ready to be used by another employee.
The non-functional requirements are defined by two constraints:
■ The interaction takes place through a touch screen.
■ The codes of products and customers can be entered through a bar code
As a consequence of the first constraint we must assume that a keyboard
is not available. Since the touch screen operates as a mouse, all the input
Figure 14.6 Initial and acquisition screen. Copyright © 2005 Sun Microsystems, Inc. All rights
reserved. Reproduced by permission of Sun Microsystems, Inc.