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  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

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

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? *

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

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

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

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

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

WIKPEDIA EXPLANATION OF USE CASES AND USE CASE SPECIFICATIONS  An excellent explanation of use cases and use case specificationsexplanation

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

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

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.