UP Development - 1.Inception (Cont’d)

- A Use Case contains the set of possible scenarios for achieving a goal

- The Use Case pulls Goals and Scenarios together, Each scenario says how 1 condition unfolds

• The Use Case Name is the goal statement
• Use Case is goal statement plus the scenarios
• Use Case : Goal Statement 와 실현 가능한 시나리오들을 한데 묶은 것이다.

- Scenario 들을 묶은 것은 성공과 실패로 이루어져 있다.

- Business UC vs System UC

• Business UseCase : Describe the operations of the business
• System UseCase : Describe the functional requirement for the SuD ( System Under Design )

- Black Box UC vs White Box UC

• Black Box UseCase
  • System 을 모르는 상태
  • Do not describe the internal workings of the system, its components, or design
• White Box UseCase
  • System 을 아는 상태
  • Can describe the internal workings of the system, its components, or design
  • Business process designers may write white-box business usecase to show how the company or organization runs its internal process

- Use Case Formats

• Brief Format
  • 간결한 one-paragraph summary
  • usually of the main success scenario
  • created in early requirements phase to understand the degree of complexity and functionality in a system
• Casual Format
  • Informal ( 약식의 ) parargraph format
  • Multiple paragraphs that cover various scenarios
• Fully Dressed Format
  • The most elaborate ( 가장 정교함 )
  • All steps and variations are written in detail
  • there are supporting sections, such as preconditions and success guarantess.
    ( 성공 조건과 전제조건 같은 부가 섹션이 정의되어 있다 )

- The Use Case is a behavioral part of the contract between various stakeholders

• Stakeholder : The stakeholder who or which initiates an interaction with the SuD or calls upon system services to achieve a goal.
• An Action or an Interaction between two Actors with Goals
• What the system must do internally to protect the Stackholders with interests

- The basic model of Use Cases is that Actors interact to achieve their goals

Main Goal 을 성취하기 위해서는 Sub Goal 을 먼저 성취하여야 한다

- The System protects the interests of all the stackholders

- A Use Case can be viewed as a behavioral contract between stakeholders with interests

• The Actors and Goals model explains how to write sentences in use case, but it Does not cover the need to describe the Internal behavior of the system under discussion
• We need to extend the Actors and Goals model to Stakeholders and Interests model
• Stakeholders and Interests model identifies what to include in the UseCase

- To satisfy the interests of the stakeholders, we need to describe three sorts of actions

• An Action or Interaction between two actors( to further a goal )
• A validation ( to protect the interest of one of the stakeholders )
• An internal state change ( on behalf of a stakeholder also to protect or further an interest of a stakeholder )

- Primpary Acotr 도 Stakeholder 이다.

- Preconditions and Postconditions

• Preconditions state what must always be true before beginning a scenario in the Use Case. They are conditions that are assumed to be true
  ( UseCase 가 실행되기 전 실행해야 하는 것 )
• Postconditions state what must be true on successful completion of the Use Case, regardless of its path
  ( 사전 조건이 만족되었을때 UseCase 가 끝나고 실행되어야 할 것 )