1. Asper School of Business University of Manitoba Systems Analysis & Design Instructor: Bob Travica Use Case description Updated: October 2014

2. 3510 Systems Analysis & Design * Bob Travica2 of 11 Outline Concept of Use Case Description Levels of Use Case Description Reading and writing Use Case Descriptions

3. 3510 Systems Analysis & Design * Bob Travica3 of 11 Use Case Diagram of the Customer Support System Use Cases grouped into system modules Note: Same actor interacts with different modules Maintain Catalog

4. 3510 Systems Analysis & Design * Bob Travica4 of 11 Use Case Description Complements Use Case Diagram A breakdown of a single use case (e.g., sequence of steps included in the function “Look up item availability”); process logic included In contrast to Use Case Diagram, Use Case Description captures variations of a Use Case Example: “Create new order” can be done via phone+clerk and via Internet ordering – 2 scenarios

5. 3510 Systems Analysis & Design * Bob Travica5 of 11 Level of Use Case Description Three levels of detail: UC Brief description Summary of what system does in response to actor’s actions UC Intermediate description Shows steps in use case, if-then UC Full description Includes Brief description, expands intermediate description, shows scenarios * UC=Use Case

6. 3510 Systems Analysis & Design * Bob Travica6 of 11 Brief Description of Create New Order Use Case Same description that is usually captured in initial Use Case Diagrams (“bird’s view” of system)

7. 3510 Systems Analysis & Design * Bob Travica7 of 11 Intermediate Use Case Description Telephone Order Scenario for Create New Order Use Case

8. 3510 Systems Analysis & Design * Bob Travica8 of 11 Full Use Case Description Superset of intermediate and brief descriptions (contains these) Consists of 11 compartments (we will use some) Shows steps (“Flow of Events”) broken down to the actor and the system side – useful!

9. 3510 Systems Analysis & Design * Bob Travica9 of 11 Full Use Case Description Telephone Order Scenario for Create New Order Use Case Computer System, Computer (steps encoded in software)

10. 3510 Systems Analysis & Design * Bob Travica10 of 11 Reading and Writing Use Case Descriptions Reading: Straightforward Writing: We will not use it much Useful to practice because it leads to other modeling techniques (activity diagram, class diagram)

11. 3510 Systems Analysis & Design * Bob Travica11 of 11 Writing Use Case Descriptions 1. Select a use case 2. Write abbreviated full description (Use case name, Scenario (if any), Business Event, Actors, Flow of steps, Exception conditions) 3. For figuring Flow of steps, - Keep in mind general system model: Input-Processing-Output - Steps should be at nearly the same level of abstraction (each makes nearly same progress toward use case completion) 4. For figuring exception conditions, focus on if-then logic.