Slides Part 2 (OOA, pages 1-128, pdf, 4 slides per page)
Slides Part 2 (OOA, pages 1-128, pdf, 4 slides per page)
Slides Part 2 (OOA, pages 1-128, pdf, 4 slides per page)
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ACTORS<br />
➠ are outside of the system<br />
➠ represent different user roles<br />
➠ can be either human beings or other systems<br />
➠ should appear in the class model<br />
➠ corresponding classes are not implemented<br />
➠ Notation:<br />
BankClerk<br />
DESCRIPTION OF SEQUENCES OF ACTIONS<br />
➠ necessary, because ovals do not convey any semantics<br />
➠ verbally or with scenarios, which are represented as diagrams<br />
➠ Distinction of<br />
• Normal cases (main flow of events)<br />
• Error cases (exceptional flow of events)<br />
33<br />
35<br />
USE CASES<br />
➠ are sets of sequences of actions<br />
➠ must have a name<br />
➠ describe the interaction between actors and the system<br />
➠ Criteria:<br />
The system supplies an observable result which is of use for the actor.<br />
➠ Notation:<br />
Process<br />
Loan<br />
EXAMPLE: USE CASE ”‘AUTHENTICATE USER”’<br />
➠ Normal case:<br />
1. System asks user for PIN<br />
2. User enters PIN<br />
3. System checks correctness<br />
➠ Exceptional cases:<br />
• User enters wrong PIN 3 times<br />
• User aborts transaction<br />
• User mistyped, presses CLEAR-Button<br />
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36
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