An Introduction to Object Modeling

Prepared by Kevin C. Dittman for

Systems Analysis & Design Methods 4ed

by J. L. Whitten & L. D. BentleyCopyright Irwin/McGraw-Hill 19981

Object ModelingAn Introduction to Object

Modeling

An Introduction to Object Modeling 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.




Object Modeling

System Concepts for Object Modeling

Objects, Attributes, Methods, and Encapsulation 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.




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.




Object Modeling(Customer)

customer number = 412209last name = Bentleyfirst name = Lonniehome phone = 317-463-9593street = 2625 DarwinDrivecity = West Lafayettestate = Indianazipcode = 47906etc.

(a)

(Book)

ISBN = 0256101329type = textbooktitle = Systems Analysis & Design Methodscopyright = 1996

(b)

(Book)

ISBN = 0256102219type = workbooktitle = Projects and Cases to AccompanySADMcopyright = 1996

Person Class(supertype)

Student Class(subtype)

Teacher Class(subtype)

Student A Student B Student C Teacher A Teacher B

(c)

OpenClose

ISBNtypetitlecopyright

Book

(d)




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




Object Modeling


Object/Class Relationships 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.




Object Modeling

Warehouse

Member ServicesSystem

Club Member

MarketingDepartment

PotentialMember

Subscription Offer

New Subscription

New MembershipPlan & Subscrition

Offer

Sales & PromotionReports

Order To Be Filled

Club Promtion

Promotion Order

Member ServicesContext Model

New Monthly orSeasonal Promotion

Past Member

SubscritionRenewal Offer

SubscritionRenewal

Member CreditStatus

AccountsReceivableData Base

Regular Order

Member ServicesDepartment

MembershipReports




Object Modeling

MemberServices

Department

MarketingDepartment

MemberServicesSystem

PastMember

PotentialMember

ClubMember

Create NewSeasonal Promotion

Request PromotionRpts.

RequestMembership Rpts.

Request Sales Rpts.

Create NewSubscription

Program

Create NewMonthly Promotion

Submit NewSubscription

Send NewSubscription Offer

SubmitSubscription

Renewal

Send SubscriptionRenewal Offer

Submit PromotionOrder

Send ClubPromotion

Submit RegularOrder

Member Services SystemUse Case Model

PromotionsSubsystem

OrdersSubsystem

MembershipSubsystem




Object Modeling

POTENTIAL OBJECTLIST

Club MemberPotential MemberPast MemberMember Services DepartmentMarketing DepartmentMember Services SystemMember AddressPromotion orderProductProduct InventoryOrder QuantityOrdered ProductCredit StatusPaymentsOrdered Product StatusPicking TicketWarehouseMember Telephone NumberSelection Of MonthTransactionAccounts ReceivablePromotion Order StatusOrder Error ReportMember Services Clerk




Object Modeling

POTENTIAL OBJECTLIST

REASON

Club Member Type of “MEMBER”Potential Member Type of “MEMBER”Past Member Type of “MEMBER”Member Services Department Not relevant for current projectMarketing Department Not relevant for current projectMember Services System Not relevant for current projectMember Address Attribute of “MEMBER”Promotion order Result of an event named “PROMOTION”

Type of “MEMBER ORDER”Product “PRODUCT”Product Inventory Attribute of “PRODUCT”Order Quantity Attribute of “MEMBER ORDER”Ordered Product “PRODUCT ON ORDER”Credit Status Attribute of “MEMBER”Payment Out of ScopeOrdered Product Status Attribute of “PRODUCT ON ORDER”Picking Ticket Potential interface itemWarehouse Not relevant for current projectMember Telephone Number Attribute of “MEMBER”Selection Of Month Type of “TITLE”Transaction Not relevant for current projectAccounts Receivable Not relevant for current projectPromotion Order Status Attribute of “MEMBER ORDER”Order Error Report Potential interface itemMember Services Clerk Not relevant for current project

Documents

An Introduction to Object Modeling