(cont’d)
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 DO NOT CITE THIS PRESENTATION.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
We are going to examine some of the key tools used for creating an analysis model.
General
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Use-cases
Use-case diagrams
Activity diagrams
Swimlane diagrams
Structured Analysis
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Data object diagrams
ERD diagrams
Data flow diagrams
Process specifications
These tools are not specific to either structured analysis or OO analysis.
OO Analysis

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Class diagrams
Packages
CRC cards
Sequence Diagrams

CpSc 372
Structured Analysis:
 Models data elements


Attributes
Relationships
 Models processes that transform data modeled using
Modeling Tools:

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Data object diagrams
ERD diagrams

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Data flow diagram
Process narrative modeled using
A data flow diagram describes information flow among a set of processes and actors.
1
*
A process narrative describes how a single process transforms input data to output data.

CpSc 372
A data object is a domain element that will be manipulated by the system.
Characteristics:


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Plays a necessary role
Characterized by attributes
Uniquely identifiable (?)
Examples:

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Roles
Events
Places
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External entities
Structures
Other things
Modeling
Object: car
Attributes:
• VIN #
• Make
• Model
• Price

CpSc 372
 Relationships
 Define connections between objects
 Cardinality
 Defines the number of items on either end of a connection
 Modality
 Defines the necessity of a connection
Entity-Relationship Diagram (ERD) insured
1
*
Person
1 owns
*
Car
1 attached
1
Trailer

CpSc 372
(See Pressman Chapter 8, Section 8.6.1, pg. 195)
Control panel commands and data
SafeHome software display information alarm type
Sensors sensor status telephone tones
Panel display
Alarm
Telephone line
External entities
(squares)
Data flows
(directed edges)
Processes
(circles)
Notice that the system is represented as a single bubble.
This is known as a level 0 DFD , or a context diagram .

CpSc 372
(See Pressman Chapter 8, Section 8.6.1, pg. 196)
Each DFD reveals progressively more detail than the DFD that preceded it.
Level 1 DFD: commands and data
Control panel
Interact with user
Configure request
Start/stop request
Configure system password
Activate / deactivate system
Refinement continues until each bubble can be (easily) implemented as a program module.
Process password
…
…
…

CpSc 372
(See Pressman Chapter 8, Section 8.6.4, pg. 200)
… password
Process password
…
A process specification describes all of the flow processes in the final (most detailed) DFD.
“The process password transform performs password validation at the control panel for the SafeHome security function. Process password receives a four-digit password from the interact with user function. The password is first compared to the master password stored within the system …”
A process specification can be represented as a collection of process narratives.

CpSc 372
(See Pressman Chapter 8, Section 8.6.1, pg. 195)
Scope document
Grammatical parse
Level 0
DFD
Develop process narratives
Grammatical parse
Next level
DFD
(nouns = external entities, data/control objects, data stores)
(verbs = processes)
Note that nouns and verbs are associated with one another.

CpSc 372
 Level 0 DFD should contain only a single bubble
 All arrows and bubbles should be meaningfully labeled
 Refinement begins by isolating next level processes, data objects, and data stores
 Refine only one bubble at a time
 Data flow continuity must be maintained between levels

CpSc 372
The Video Library Management System
An excerpt from the scope document:
The video library management system will interact with the user through a web-based browser interface. When the user logs into the system, the system will determine the user’s access privileges based on the user configuration database. If the user is an administrator, the system will allow the user to enter new movie titles, new actor information, etc. If the user is not an administrator, the system will allow the user to query the system based on movie title, actor, director, etc.
What might the level 0 DFD look like? Level 1?

CpSc 372
And a Bit of Review
Another excerpt from the scope document:
The system will allow the user to store a number of information elements with each video, director, and actor. Each video will be characterized by a title, a genre descriptor, a short synopsis, a list of directors, a list of actors, a rating, and a UPC code.
Each actor and director will be characterized by a first and last name, a year of birth, and a brief biography. When the user is viewing a video entry, they will be able to retrieve the full actor
(or director) information by clicking the actor’s (or director’s) name.
What would be an appropriate
ERD diagram for this excerpt?