Asper School of Business
University of Manitoba
Systems Analysis & Design
Instructor: Bob Travica
Use Case description
Updated: October 2014
Outline

Concept of Use Case Description

Levels of Use Case Description

Reading and writing Use Case
Descriptions
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Use Case Diagram of the
Customer Support System
Use Cases
grouped into
system
modules
Maintain
Catalog
Note: Same actor
interacts with
different modules
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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
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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
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Brief Description of Create New
Order Use Case
• Same description that is usually captured in initial
Use Case Diagrams (“bird’s view” of system)
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Intermediate Use Case Description
Telephone Order Scenario for
Create New Order Use Case
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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!
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Full Use Case Description
Telephone Order
Scenario
for
Create New Order
Use Case
Computer System, Computer
(steps encoded in software)
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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)

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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.
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