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Use Cases 2
CSSE 371 Software Requirements and Specification
Mark Ardis, Rose-Hulman InstituteSeptember 20, 2004
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Outline Computing in 1968 Template for use cases Extending use cases Including use cases
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Computing in 1968
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Computing in 1968
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Computing in 1968
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Computing in 1968
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Doug Engelbart Video
(see link from ANGEL course page)
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Refining Use Cases Describe sequences of events for flows Describe pre-conditions Describe post-conditions Fill in special requirements
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Use Case Template
A. NameB. Brief descriptionC. ActorsD. Basic flowE. Alternate flowsF. Pre-conditionsG. Post-conditionsH. Special requirements
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Microwave Example
User
Cook Food
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Cook Food Use Case 1/4
A. Name: Cook FoodB. Brief description: User places food in
microwave and cooks it for desired period of time at desired power level.
C. Actors: User
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Cook Food Use Case 2/4
D. Basic flow:1. User opens door and places food in unit2. User enters time for cooking3. User pushes start button4. Unit cooks food5. Unit beeps
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Cook Food Use Case 3/4
E. Alternate flows1. User cancels time before starting2. User cancels cooking before finished3. User selects reduced power level before
pushing start button
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Cook Food Use Case 4/4
F. Pre-conditions Unit is plugged in Unit is in ready state
G. Post-conditions Food is cooked or user cancelled operation
H. Special requirements Timer should display remaining time to
finish while cooking Default power setting should be "high"
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Extending Use Cases
Extend an existing use case instead of redefining it
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Microwave Extension
User
Cook Food
Slice Food
<<extend>>
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Including Use Cases
Frequent sequences of events may be defined as use cases
Including a use case is like calling a subroutine
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Microwave Inclusion
User
Cook Food
Set Timer
<<include>>
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Cook Food Inclusion
D. Basic flow:1. User opens door and places food in unit2. User performs Set Timer use case3. User pushes start button4. Unit cooks food5. Unit beeps
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