Object Modeling
An Introduction to Object Modeling

An Introduction to Object Modeling

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The approach of using object modeling during systems analysis
and design is called object-oriented analysis.
 Object-oriented analysis (OOA) techniques are used to (1)
study existing objects to see if they can be reused or adapted for
new uses, and to (2) define new or modified objects that will be
combined with existing objects into a useful business
computing application.
The object-oriented approach is centered around a technique
referred to as object modeling.
 Object modeling is a technique for identifying objects within
the systems environment, and the relationships between those
objects.
Prepared by Kevin C. Dittman for
Systems Analysis & Design Methods 4ed
by J. L. Whitten & L. D. Bentley
1
Copyright Irwin/McGraw-Hill 1998
Object Modeling
System Concepts for Object Modeling

Objects, Attributes, Methods, and Encapsulation
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The object-oriented approach to system development is based on
the concept of objects that exist within a system’s environment.
Objects are everywhere
Webster’s Dictionary definition of an object.
 Something that is or is capable of being seen, touched, or
otherwise sensed.
In object-oriented approaches to systems development the
definition of an object is as follows:
 An object is something that is or is capable of being seen,
touched, or otherwise sensed, and about which users store data
and associate behavior.
Prepared by Kevin C. Dittman for
Systems Analysis & Design Methods 4ed
by J. L. Whitten & L. D. Bentley
2
Copyright Irwin/McGraw-Hill 1998
Object Modeling
System Concepts for Object Modeling

Objects, Attributes, Methods, and Encapsulation

The types of objects may include a person, place, thing, or event.
 An employee, customer, vendor, and student are examples of
person objects.
 A particular warehouse, regional office, building, and room are
examples of place objects.
 A product, vehicle, equipment, video tape, or a window
appearing on a users display monitor are examples of thing
objects.
 An order, payment, invoice, application, registration, and
reservation are examples of event objects.
Prepared by Kevin C. Dittman for
Systems Analysis & Design Methods 4ed
by J. L. Whitten & L. D. Bentley
3
Copyright Irwin/McGraw-Hill 1998
Object Modeling
(Customer)
customer number = 412209
last name =
Bentley
f irst name =
Lonnie
home phone =
317-463-9593
street =
2625 Darw in
Drive
city =
West Laf ayette
state =
Indiana
zipcode =
47906
etc.
(a)
(Book)
(Book)
ISBN = 0256102219
type = w orkbook
title = Projects and Cases to Accompany
SADM
copyright = 1996
ISBN = 0256101329
type = textbook
title = Systems Analysis & Design Methods
copyright = 1996
(b)
Person Class
(supertype)
Student Class
(subtype)
Student A
Student B
Teacher Class
(subtype)
Teacher A
Student C
Teacher B
(c)
Book
ISBN
type
title
copyright
Open
Close
(d)
Prepared by Kevin C. Dittman for
Systems Analysis & Design Methods 4ed
by J. L. Whitten & L. D. Bentley
4
Copyright Irwin/McGraw-Hill 1998
Object Modeling
System Concepts for Object Modeling

Object/Class Relationships

Objects and classes do not exist in isolation.
 The things they represent interact with, and impact one another
to support the business mission.
 Thus there is an object/class relationship.
• An object/class relationship is a natural business association that
exists between one or more objects/classes.

For example, consider the object classes customer and order
that may exist in a typical information system and how they
interact.
• a CUSTOMER PLACES zero or more ORDERs
• an ORDER IS PLACED BY one and only one CUSTOMERs
Prepared by Kevin C. Dittman for
Systems Analysis & Design Methods 4ed
by J. L. Whitten & L. D. Bentley
5
Copyright Irwin/McGraw-Hill 1998
Object Modeling
System Concepts for Object Modeling

Object/Class Relationships
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
We graphically illustrate the association(relationship) between two
classes as a connecting line.
 A verb phrase describes the relationship.
 All relationships are implicitly bi-directional, meaning that they
can interpreted in both directions.
What is multiplicity?
 Multiplicity defines the minimum and maximum number of
occurrences of one object/class for a single occurrence of the
related object/class.
 Because all relationships are bi-directional, multiplicity must be
defined in both directions for every relationship.
Prepared by Kevin C. Dittman for
Systems Analysis & Design Methods 4ed
by J. L. Whitten & L. D. Bentley
6
Copyright Irwin/McGraw-Hill 1998
Object Modeling
Member Services
Context Model
Subscription Offer
Club Promtion
New Subscription
Promotion Order
Club Member
Regular Order
Potential
Member
Subscrition
Renewal Offer
Past Member
Member Credit
Status
Subscrition
Renewal
Order To Be Filled
Member Services
System
Membership
Reports
New Membership
Plan & Subscrition
Offer
Accounts
Receivable
Data Base
Sales & Promotion
Reports
Warehouse
New Monthly or
Seasonal Promotion
Marketing
Department
Member Services
Department
Prepared by Kevin C. Dittman for
Systems Analysis & Design Methods 4ed
by J. L. Whitten & L. D. Bentley
7
Copyright Irwin/McGraw-Hill 1998
Object Modeling
Member Services System
Use Case Model
Submit Regular
Order
Member
Services
Department
Past
Member
Club
Member
Request Sales Rpts.
O rd e rs
S ub s y s te m
Submit Promotion
Order
M e m b e rs hi p
S ub s y s te m
Request
Membership Rpts.
Submit
Subscription
Renewal
Create New
Subscription
Program
Marketing
Department
Submit New
Subscription
Send Subscription
Renewal Offer
Send New
Subscription Offer
Create New
Create New
Seasonal Promotion Monthly Promotion
Request Promotion
Rpts.
P ro m o tio ns
S ub s y s te m
Potential
Member
Prepared by Kevin C. Dittman for
Systems Analysis & Design Methods 4ed
by J. L. Whitten & L. D. Bentley
Send Club
Promotion
Member
Services
System
8
Copyright Irwin/McGraw-Hill 1998
Object Modeling
POTENTIAL OBJECT
LIST
Club Member
Potential Member
Past Member
Member Services Department
Marketing Department
Member Services System
Member Address
Promotion order
Product
Product Inventory
Order Quantity
Ordered Product
Credit Status
Payments
Ordered Product Status
Picking Ticket
Warehouse
Member Telephone Number
Selection Of Month
Transaction
Accounts Receivable
Promotion Order Status
Order Error Report
Member Services Clerk
Prepared by Kevin C. Dittman for
Systems Analysis & Design Methods 4ed
by J. L. Whitten & L. D. Bentley
9
Copyright Irwin/McGraw-Hill 1998
Object Modeling
POTENTIAL OBJECT
LIST
Club Member
Potential Member
Past Member
Member Services Department
Marketing Department
Member Services System
Member Address
Promotion order
Product
Product Inventory
Order Quantity
Ordered Product
Credit Status
Payment
Ordered Product Status
Picking Ticket
Warehouse
Member Telephone Number
Selection Of Month
Transaction
Accounts Receivable
Promotion Order Status
Order Error Report
Member Services Clerk
Prepared by Kevin C. Dittman for
Systems Analysis & Design Methods 4ed
by J. L. Whitten & L. D. Bentley
REASON
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Type of “MEMBER”
Type of “MEMBER”
Type of “MEMBER”
Not relevant for current project
Not relevant for current project
Not relevant for current project
Attribute of “MEMBER”
Result of an event named “PROMOTION”
Type of “MEMBER ORDER”
“PRODUCT”
Attribute of “PRODUCT”
Attribute of “MEMBER ORDER”
“PRODUCT ON ORDER”
Attribute of “MEMBER”
Out of Scope
Attribute of “PRODUCT ON ORDER”
Potential interface item
Not relevant for current project
Attribute of “MEMBER”
Type of “TITLE”
Not relevant for current project
Not relevant for current project
Attribute of “MEMBER ORDER”
Potential interface item
Not relevant for current project
10
Copyright Irwin/McGraw-Hill 1998