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Title:

Use Cases

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Overview Use cases are used primarily for requirements specification. They model specifically how different actors will use the system under analysis They are ... – PowerPoint PPT presentation

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Title: Use Cases


1
Use Cases
2
Overview
  • Use cases are used primarily for requirements
    specification.
  • They model specifically how different actors will
    use the system under analysis
  • They are often created in several iterations
    starting with the most general statements, then
    decomposing them into more and more specific
    cases.

3
Symbols
An actor is someone or something that interacts
with your system, that uses it. It is normally a
type like customer rather than a particular
person or thing
A use case is an oval that describes a use, or
requirement of the system. It always begins with
a verb, and can be numbered.
4
Actor and Use Case
A line shows that an actor uses a particular use
case
5
Uses Relation
The uses relation says that one or more use cases
use another. It has implications in terms of
later programming, implying that both can rely on
a single module or class
6
Extends Relation
The extends relation models possible inheritance
in terms of generalization/specialization. Here
the Create Report is the general use case and the
two types of reports are specialized cases.
7
System Boundary
One can use a system boundary box to show the
limits of the system under consideration
Not part of the system
8
Decomposition
Individual use cases can be decomposed into
more specific use cases. (Note the numbering)
9
Description
  • In addition each use case can be described
    verbally, there are many ways to do this.
  • Often the text identifies the use case,
    identifies the triggerthe event that causes
    the use case to be used, and the steps involved
    in the use case.
  • The next slide has an example

10
Example
  • Use Case 1.1 Enter New Project
  • Primary Actor Project Worker
  • Trigger project worker begins new project
  • Use Case Steps
  • Worker Opens main form
  • Selects new Project
  • 3. Enters Project title, start date, estimated
    duration, other relevant information
  • 4. Worker saves new project to database
  • 5. Worker exits or chooses to begin a task on new
    or previous project
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