Page 91 - Software and Systems Requirements Engineering in Practice

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C h a p t e r 3 : E E l i c i t i n g R e q u i r e m e n t s 61 61
System Response
Step Actor (Bank Teller) Output
1 Give check Can I see your ID?
to teller
2 Give ID ID is okay
to teller
3 Put ID away Return ID
4 Check account for Hold on account to
enough money cover check amount
5 Take money Cash check
TABLE 3.2 Sample Use Case Activity
Another problem with textual use cases is the occurrence of
crosscutting issues that require use case modifications. With graphical
models, it is a relatively simple matter to make changes, since
the CASE tool handles the updating of other diagrams. Scenario
diagrams take the place of tabular descriptions of activities (see
Figure 3.12). With text, a crosscutting change can involve heavy
manual effort to keep primary and alternate use cases across all
relevant documents up-to-date, especially going into the activity
tables and changing steps and responses.
More information about model-driven requirements engineering
and the effective use of graphical modeling techniques can be found
in the next chapter.
Cash a Check Make a Withdrawal
Includes Includes

Check Account Balance

FIGURE 3.11 Graphical nature of use cases