SYS366

1. SYS366 The Last Stage in Analysis: System Use Case Descriptions created through the Use Case Authoring Process

2. Where did we come from? • Identified Stakeholder categories/types • Identified business areas & basic processes • Completed interviews with stakeholder rep. • Identified Business Use Cases • Built a Business Use Case Diagram • Wrote Business Use Case Descriptions • Created Actor/Activity Tables from the Business Use Case Descriptions

3. System Use Cases • Identify actors for System Use Cases • look for an actor who specifically interacts with the system  humans, devices, other systems, etc • Actors are not part of the system. They are just outside the system boundary and are visible to the system. • Identify activities for System Use Cases • Anything the system must do to achieve the use case result • Happens only inside the system boundary • Systems Use Case Diagram • Systems Use Case Descriptions • Systems Use Case Authoring Process

4. Systems Use Cases • convert Business Use Cases to system requirements. • How? • B.U.C. description leads to • B.U.C. actor/activity table leads to • System Use Case Diagram & Description

5. Documenting Systems Use Cases • Systems Use Case Diagram • Shows the functionality that the system will provide and which users (actors) will communicate with the system • Done using Rational Rose • acts as a place holder for the Systems Use Case Description • is a visual index, providing a context for the descriptions

6. Systems Use Cases Diagram • Actors are represented by a ‘stick’ figure • Systems Use Cases are shown as an oval • Associations are a customer IDlabeled arrow line —–—–––

7. 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

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

9. Systems Use Case Descriptions • The (systems) use case descriptions 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 descriptions themselves. * *Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, p. 30

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

11. Systems Use Case Descriptions • “The use case description 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

12. Systems Use Case Descriptions • “Just like a story, every use case should have • a clear beginning (how the actor starts the use case) • Middle (how the system and actors work together) • End how the use case is concluded”* *Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, p. 24

13. Systems Use Case Description • Describes typical ways (or cases) of using the system* with processing details • Not a complete description of all possible ways that some task is performed by actor • Does not say how the system is designed or implemented (e.g. J2EE or .NET) *Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, pp. 24-25

14. Systems Use Case Descriptions • The systems use case description 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: sequential, decision, looping • All exception and error logic

15. Today • Systems Use Case Descriptions • Systems Use Cases Authoring

16. Systems Use Cases Authoring • The Systems Use Cases and its description evolves through the authoring process.* *Systems Use Cases Modeling by Bittner & Spence, Page 152

17. The Authoring Life Cycle Discovered Briefly Described Essential Outline Bulleted Outline Detailed Description Systems Use Case Specification

18. The Authoring Life Cycle • State 1: Discovered * • Through Interviews with the Stakeholders • Through experience • Shown on a Systems Use Case diagram • Place holder for the Systems Use Case description • A visual index, providing a context for the descriptions *Systems Use Cases Modeling by Bittner & Spence, Pages 153 - 154

19. The Authoring Life Cycle • State 2: Briefly Described • Once the Systems Use Case has been identified, it should be described • Example: Create Vehicle Reservation by Phone This Systems Use Cases describes how the actor, a Call Centre Employee, uses the system to reserve a vehicle for a specified period at a customer’s request.

20. The Authoring Life Cycle • State 3: Bulleted Outline • Captures the simple steps of the use case in short sentences organized sequentially

21. Bulleted Outline • Example of a Systems Use Case

22. Bulleted Outline • Let’s create a bulleted outline for one of your use cases