Use Cases 2

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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

1. Name
2. Brief description
3. Actors
4. Basic flow
5. Alternate flows
6. Pre-conditions
7. Post-conditions
8. Special requirements

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Microwave Example
Cook Food
User
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Cook Food Use Case 1/4

1. Name Cook Food
2. Brief description User places food in microwave
   and cooks it for desired period of time at
   desired power level.
3. Actors User

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Cook Food Use Case 2/4

• Basic flow
• User opens door and places food in unit
• User enters time for cooking
• User pushes start button
• Unit cooks food
• Unit beeps

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Cook Food Use Case 3/4

• Alternate flows
• User cancels time before starting
• User cancels cooking before finished
• User selects reduced power level before pushing
  start button

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Cook Food Use Case 4/4

• Pre-conditions
• Unit is plugged in
• Unit is in ready state
• Post-conditions
• Food is cooked or user cancelled operation
• 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
ltltextendgtgt
User
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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
ltltincludegtgt
User
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Cook Food Inclusion

• Basic flow
• User opens door and places food in unit
• User performs Set Timer use case
• User pushes start button
• Unit cooks food
• Unit beeps