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Back to Analysis Phase - Use Case Design

(from the Craig Larman book)

Use cases goal: discover and record functional requirements by
writing stories of using a system to help fulfill stakeholder goals.

Definitions:

• Actor: something with behavior. E.g. person (with role), computer system
  or organization (user, mailbox owner)
• Primary Actor: actors that have their goals fulfilled through using services of the system
• Supporting Actor: actor that provides a service to the system under discussion
• Scenario: specific sequence of actions and interactions between actors and
  the system. ("scenario" = "use case instance")
  A scenario is one particular story of using the system, or one path through the use case.
  
• Use case: collection of related success and failure scenarios describing actors
  using the system to support a goal.

Key concept: do requirements work with focus on how a system can add value and fulfill goals.


Recommendations:

• Name use cases starting with a verb (e.g. "Leave Voice Mail")
• Early on, write use cases in an essential style: focus on actor intent and
  leave out the user interface
• Record primary actors and goals in an actor-goals list. Example:
  

  Actor	Goal
  User	leaves message
  Mailbox Owner	logs in with password
  Mailbox Owner	retrieves messages
  Mailbox Owner	changes greeting
  Mailbox Owner	changes password

  
  

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