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SYS466

SYS466. Systems Use Case Specifications. Systems Use Case Diagrams and Specifications. Based on the dialog metaphor. Dialog Expresses that the User and Computer Interact by Sending Messages. Designing Dialogs.

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SYS466

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  1. SYS466 Systems Use Case Specifications

  2. Systems Use Case Diagrams and Specifications • Based on the dialog metaphor

  3. Dialog Expresses that the User and Computer Interact by Sending Messages

  4. Designing Dialogs • The process of designing the overall sequences that users follow to interact with an information system • the sequence in which information is displayed to and obtained from the user

  5. Sequence • understanding how the user will interact with the system • clear understanding of user, task, technological and environmental characteristics

  6. Questions to ask to identify system use cases* • What are users in this role trying to accomplish? • To fulfill this role, what do users need to be able to do? • What are the main tasks of users in this role? • What information do users in this role need to examine, create, or change? • What do users in this role need to be informed of by the system? • What do users in this role need to inform the system about? *http://www.agilemodeling.com/artifacts/systemUseCase.htm

  7. Systems Use Case Diagram • Place holder for the Systems Use Case Specification • A visual index, providing a context for the Specifications *Systems Use Cases Modeling by Bittner & Spence, Pages 153 - 154

  8. Systems Use Case Specifications • The (systems) use case specifications provide the substance of the (systems) use case model and they are the basis for most of the …modeling work…More than 90% of the (systems) use-case model lies beneath the surface, in the textual use-case specifications themselves. * *Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, p. 30

  9. Systems Use Case Specifications • “(Systems) use cases are more than just a named ellipse and a brief Specification. For each (systems) use case there will also be a (systems) use-case specification where the full story of the use case is told.”* *Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, p. 30

  10. Systems Use Case Specifications • “The use case specification tells a story of how a system and its actors collaborate to achieve a specific goal • This collaboration takes the form of a dialog between the system and its actors • It is a step-by-step description of a particular way of using a system”* *Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, p. 24

  11. Systems Use Case Specification • Not a complete specification of all possible ways that some task is performed • Describes typical ways (or scenarios) of using the system* *Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, pp. 24-25

  12. WIKPEDIA EXPLANATION OF USE CASES AND USE CASE SPECIFICATIONS • An excellent explanation of use cases and use case specifications

  13. Systems Use Case Specifications • Discussion of formal and informal use case specifications – Ambler • Discussion of the essential use case specification - Ambler

  14. Systems Use Case Specifications • The systems use case specification must include: • Who the actors are and how many of them are interacting with the system at any point in time • What data is used and how • All normal logic

  15. The Use Case Specification • One of the best checks of whether a use case specification is finished is to ask if you could use the use case to derive system tests. • The best way to tell if the use cases fit the purpose is to pass them along to the…test team for test design. • If the team is satisfied that they can use the use cases to support this activity, then the use case specifications contain sufficient levels of detail.

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