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USE CASES

USE CASES. Rob Caldwell Fernanda Albert Stephan Krawec. EVENT TABLE. BEST PRACTICE. Plan and manage every project so it is use case driven. use cases are always the focus when defining system requirements and designing, implementing , and testing the system. Use Case Views.

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USE CASES

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  1. USE CASES Rob Caldwell Fernanda Albert Stephan Krawec

  2. EVENT TABLE

  3. BEST PRACTICE • Plan and manage every project so it is use case driven. • use cases are always the focus when defining system requirements and designing, implementing, and testing the system.

  4. Use Case Views • Use cases consist of two tiers: • Overview level: • Event table and use case diagram • Detailed level: • Use case description • Activity diagram

  5. USE CASES AND ACTORS • Source • Person or thing initiating the business event • Must be external to the system • Actor • Person or thing that touches the system • Lies outside of automation boundary • Identifying actors at the right level of detail • Use case is a goal that the actor wants to achieve

  6. Developing a Use Case Diagram(part 1) • Iterative process translates business events into use cases • Identify the actors and roles for each use case • Identify the system response to the business event • Distinguish between temporal (time) and state events (an attribute change) • The data of the system stabilizes after the completion of the use case • Use cases contain a sequence of steps to execute the process of the business event • A single use case can have variations – scenario

  7. Developing a Use Case Diagram (part 2) • Sometimes a use case can be further broken down • Divide one large use case into two • Define another use case based on a process (be careful – each process has to be a complete process a user would do by itself) • Use case descriptions written at (3) levels of detail • Brief Description - Summary statement • Intermediate Description - Expands the brief description • Fully Developed Description - Expands intermediate description with the textual flow of events or an activity diagram

  8. Use case diagram cont’d summarizes business events table * Actors can be a person, another system or time

  9. Automation boundary line drawn around the entire set of use cases. Defines the interface between actors and computer system.

  10. Use Case Organization Package symbol used to organize use cases into subsystems

  11. A Use Case Diagram of the Customer Support System (by Subsystem)

  12. « Includes » Relationships • «includes» relationship • Use case calling services of another use case (like calling a common subroutine) • Example: “Look Up Item Availability” • Notation • Relationship denoted by connecting line with arrow • Direction of the arrow indicates calling and called use cases

  13. An Example of the Order-entry Subsystem With «Includes» Use Cases

  14. Brief Description of Create New Order Use Case

  15. Intermediate Description of Telephone Order Scenario for Create New Order Use Case

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