Analysis Modeling
CpSc 372:
Introduction to
Software Engineering
Jason O. Hallstrom
jasonoh@cs.clemson.edu
Authorship Disclaimer. These slides are intended to serve as teaching instruments for an undergraduate course in Software
Engineering. While the slides were formatted by Dr. Hallstrom, the content is compiled from other sources, including the readings
listed on the course website, Dr. Pressman’s Software Engineering textbook, and various internet materials. In almost every case,
the ideas belong to someone other than Dr. Hallstrom. Indeed, text is often quoted verbatim without an explicit citation (to improve
the readability of the slides). The original authors retain all copyrights. If you are interested in citing any of the material in these
slides, please contact Dr. Hallstrom for the original source(s). DO NOT CITE THIS PRESENTATION. THE CONTENT SHOULD NOT BE
ATTRIBUTED TO DR. HALLSTROM. SEE DR. HALLSTROM IF YOU HAVE ANY QUESTIONS.
CpSc 372
The Analysis Model
The analysis model consists of a wide variety of
diagrammatic forms used to bridge an important gap.
System
Description
Design
Model
Analysis
Model



System information
System function
System behaviors
Purpose:



Describe what the customer wants built
Establish the foundation for the software design
Provide a set of validation requirements
CpSc 372
Some Rules of Thumb

Make sure all points of view are covered

Every element should add value

Keep it simple

Maintain a high level of abstraction

Focus on the problem domain

Minimize system coupling
CpSc 372
Analysis Modeling Approaches
Structured Analysis:

Models data elements
Object-Oriented Analysis



Attributes
 Relationships

Models processes that
transform data
Models analysis classes
Data
 Processes

Models class collaborations
Techniques from both approaches are typically used in
practice.
CpSc 372
A Roadmap
We are going to examine some of
the key tools used for creating an
analysis model.
General




Use-cases
Use-case diagrams
Activity diagrams
Swimlane diagrams
Structured Analysis




Data object diagrams
ERD diagrams
Data flow diagrams
Process specifications
These tools are not specific
to either structured analysis
or OO analysis.
OO Analysis




Class diagrams
Packages
CRC cards
Sequence Diagrams
CpSc 372
Use-Cases
“[Use-cases] are simply an aid to defining what
exists outside the system (actors) and what
should be performed by the system (use-cases).”
Key Points:
–Ivar Jacobson

A scenario that describes a thread of usage for achieving a
functional requirement

Actors represent roles people, devices, or external systems
play

System internals are ignored
Example:
See Pressman Chapter 8, Section 8.5.1, pg. 190
CpSc 372
The Key Elements of a Use-Case

A descriptive name for the scenario


The primary actor in the scenario


Remember why
we’re interested in
use-cases!
How was the scenario initiated?
The “sunny day” scenario


What assumptions are being made?
Scenario trigger


What is the actor trying to accomplish?
Scenario pre-conditions


Who is interacting with the system?
The primary actor’s goal


e.g., “Customer Checkout”, “Browse Products”
In the best case, how does the user interact with the system?
Exceptions

What might go wrong?
CpSc 372
Developing a Use-Case

What are the main tasks or functions that are
performed by the actor?

What system information will the actor acquire,
produce or change?

Will the actor have to inform the system about
changes in the external environment?

Does the actor wish to be informed about
unexpected changes?

…
CpSc 372
Example: The Online Bookstore
Consider the following excerpt from the initial
scope document of a system that will be used
by a local bookseller.
The Online Bookstore System (OBS) will be a web-based
application that allows customers to browse and purchase
online product offerings. The application will support the notion
of an online shopping cart, similar to other online retailers such
as Amazon.com. The checkout features of the system will be
integrated with our credit card transaction processor, as well
as our internal billing system. The system will also provide an
administrator-view that will allow authorized employees to view
and administer products, customers, and orders.
Based on this description, what are the key use-cases?
CpSc 372
Activity Diagrams
ent er password
and user ID
For complex use-cases,
the process flow may be
difficult to understand.
valid passwor ds/ ID
invalid passwor ds/ ID
select major f unct ion
prompt f or reent ry
ot her f unct ions
m ay also be
select ed
Activity diagrams
provide a graphical view of
the interactions in a usecase.
input t r ies r em ain
selec t surveillance
no input
t r ies r em ain
t hum bnail views
select a specif ic cam er a
select specif ic
camera - t humbnails
select camera icon
Example:
See Pressman Chapter
8, Section 8.5.2, pg. 192
view camera out put
in labelled window
prompt f or
anot her v iew
exit t his f unct ion
see anot her cam er a
CpSc 372
Swimlane Diagrams
In some cases, it help to
indicate which actors (or
analysis classes) are
responsible for which
activities.
A swimlane diagram
serves this purpose.
Example:
See Pressman Chapter
8, Section 8.5.3, pg. 193
homeowner
c a m e ra
i n t e rf a c e
ent er pas sword
and us er ID
valid p asswo r d s/ ID
in valid
p asswo r d s/ ID
s elec t m ajor f unc t ion
o t h er f u n ct io n s
m ay also b e
select ed
prom pt f or reent ry
in p u t t r ies
r em ain
select s urveillanc e
n o in p u t
t r ies r em ain
t h u m b n ail views
select a sp ecif ic cam er a
s elec t s pecif ic
c am era - t hum bnails
selec t cam era ic on
generat e v ideo
out put
view c am era out put
in labelled window
prom pt f or
anot her v iew
exit t h is
f u n ct io n
see
an o t h er
cam er a
CpSc 372
Use-Case Diagrams
You’ll probably have a lot of
use-cases!
Online Bookstore
System
Browse products
Use case diagrams (UCD) provide
a diagrammatic table of contents,
and a high-level overview of the
system.
Add products to
shopping cart
View shopping cart
Customer
Diagrams Show:



Actors
Use-cases
Relationships among them
Credit card
transaction processor
Checkout
Billing system
Example UCD