Summary

A use case describes what a system does but it doesn’t specify how it does it.

Use Case Diagram

Use Case Description

Has 2 types:

• Main flow events:
  • Customer enter valid PIN number and login successfully.
• Exceptional flow:
  • Customer cancel a transaction.
  • Customer enters an invalid PIN number.

Use Case Format

Use Case UC1: ...
Level: User-level goal

Primary Actor: Cashier
Preconditions:
	- ...
	  
Stakeholders and their Interests:
[person...] wants ...
[person...] wants ...
...
Main Success Scenario:
1. [person...] do ...
2. [person...] do ...
   
Extensions (oralternatives):
a*. At any time, system fails: ...
   1 [do what]
   2 [do what]
3a. what if ...
   1 [do what]
   2 [do what]
3b. what if ...
   1 [do what]
   2 [do what]
3-6a. what if ...
   1 [do what]
   2 [do what]
...
Sepcial Requirements:
	- Touch screen uI on a large flat panel monitor. Text must be visible from 1 meter....
	  ...
Technology and Data Variations
3a. ...
3b. ...
7a. ...
7b. ...

Frequency of Occurrence:
- Could be nearly continuous.
  
Open Issues:
- Should we support ...