The relationship??™s name would be the name of the Watch Model and would
be shown in the cell. Fig. 9.6 shows how this would provide a useful visual
FIGURE 9.4 Logical watch as a cycle of applications
MODELING LANGUAGE 203
FIGURE 9.5 Watch Family diagram
FIGURE 9.6 Watch Family as a matrix
204 DIGITAL WRISTWATCH
overview of which potential combinations of Logical Watches and Displays had
been used, how often each Logical Watch and each Display had been used, and
which potential combinations remained as possible openings for new products.
The matrix format would also collect the Watch Models, Logical Watches, and
Displays together into their own areas, without the rather clumsy group symbol of
the graphical diagram.
9.3.7 Rules of Watch Applications
The main need for rules and constraints in theWatch applications, as in most DSM
languages, was in the relationships. The main relationship was the Transition
between States, triggered by a Button and causing various kinds of actions. This
was a clear case of an n-ary relationship: one relationship connecting several
objects.
One question was how much we wanted to allow the aggregation of several
transitions into one composite transition. For instance, it would have been possible to
allow the same transition to come from many States: for example, a transition to the
Stop state, triggered by the Mode button, would often be appropriate for several
States.
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