1
AN
OBJECT-ORIENTED
SYSTEMS ANALYSIS AND DESIGN
METHODOLOGY
Planning Feasibility Study (optional) Requirements Determination
Conceptual Design Physical Design Construction and/or Purchase
(prototype) Training Conversion - old to new Implementation Evolution - maintenance &
enhancements
SYSTEMS DEVELOPMENT LIFE CYCLE (SDLC)SYSTEMS DEVELOPMENT LIFE CYCLE (SDLC)A
naly
sis
Desig
n
3
METHODOLOGY OVERVIEW
• Methodology defined: The way something gets done. The strategy, steps, directions, or actions.
• Methodologies can be:• purchased
• created
• combination of both
• Thousands available for developing information systems
4
METHODOLOGY OVERVIEW
• Classifications of Methodologies• Traditional• Structured Analysis and Design• Information Modeling/Engineering• Object-Oriented
• Prototyping is a technique - (some say that it
is a methodology)
5
The Traditional Methodology
• Applicable for small teams on small projects
• Functional perspective of problem domain
• Informal, unstructured, unrepeatable,
unmeasurable, ad-hoc way
• Tools used to support it are okay
(1950s - now)
6
Traditional Methodology Tools
-----------TECHNIQUES & TOOLS REPRESENTING-----------System Data Communication ProcessFlows with users Logic
Forms,
Layouts,
Grid Charts
System
Flowcharts
English
Narrative,
Playscript,
Program
Flowcharts,
HIPO Charts
Interviews
7
Structured Analysis and Design Methodology
• Data Flow methodology (synonym)
• Compliments Structured Programming
• Very popular - perhaps the leading one
• Can be repeatable, measurable, & automated
• CASE brought significant assistance
• 1) Yourdon, and 2) Gane & Sarson
• Functional perspective of problem domain
• Describes the real world as data flowing through the information system, being transformed from inputs to outputs
(mid-1970s - now)
8
Structured Analysis and Design Methodology Tools
-----------TECHNIQUES & TOOLS REPRESENTING-----------System Data Communication ProcessFlows with users Logic
Data Dictionary,
Data Structure
Diagrams,
Entity-
Relationship
Diagrams
Data Flow
Diagram
Decision
Tree/Table,
Structured
English,
Structure
Charts,
Warnier/Orr
Diagram
Interviews,
User Reviews,
JAD sessions
Reconcile Account Balances
Pay a
Bill
Withdraw Funds from an Account
Deposit Funds into an Account
Bank
Creditor
Employer
Other Income Source
Bank
Monthly Account Statements
Account Transactions
Bank Accounts
Account Transactions
Bill
Payment
Monthly Statement
Account Balance
Transaction
Prior Monthly Statement
New or Modified Monthly Statement
Modified Balance
Pay
Reimbursement
Withdraw or transfer
Deposit
Payment
Modified Balance
Current Balance
(adapted from Systems Analysis andDesign Methods, 4th Edition, Whittenand Bentley, McGraw-Hill, 1998)
(adapted from Systems Analysis andDesign Methods, 4th Edition, Whittenand Bentley, McGraw-Hill, 1998)
CUSTOMER
Customer Number (PK) Customer Name Shipping Address Billing Address Balance Due
ORDER
Order Number (PK) Order Date Order Total Cost Customer Number (FK)
INVENTORY PRODUCT
Product Number (PK) Product Name Product Unit of Measure Product Unit Price
ORDERED PRODUCT
Ordered Product ID (PK) . Order Number (FK) . Product Number (FK) Quantity Ordered Unit Price at Time of Order
has placed
sold
sold as
11
Information Modeling Methodology
• Data modeling & information engineering
(synonyms)
• Describes the real world by its data, the data’s
attributes, and the data relationships
• Can be repeatable, measurable, and automated
• Data perspective of the problem domain
(early-1980s - now)
12
Information Modeling Methodology Tools
-----------TECHNIQUES & TOOLS REPRESENTING-----------System Data Communication ProcessFlows with users Logic
Business
Area
Analysis,
Entity-
Relationship
Diagrams
Business
Area
Analysis,
Process
Model
Business
Systems
Design
Interviews,
User Reviews,
JAD Sessions,
Brainstorming
13
Object-Oriented Methodology
• Object modeling
• Compliments object-oriented programming
• Can be repeatable, measurable, & automated
• Object perspective of the problem domain
• Describes the real world by its objects, the attributes,
services, and relationships
• Data & functions are encapsulated together
(mid/late-1980s - now)
14
Object-OrientedMethodology Tools
-----------TECHNIQUES & TOOLS REPRESENTING-----------System Data Communication ProcessFlows with users Logic
Object Model
Attributes
Object
Model
Object
Models
Services,
Scenarios,
Decision
Tree/Tables,
Structured
English
Interviews,
User Reviews,
JAD Sessions,
Brainstorming
15
Object-Oriented Methodology
• Revolutionary or Evolutionary?
• Most difficult aspect is the transition some people
have to make from a functional or data problem
solving strategy to an object problem solving
strategy. Some people must change from a “function
think” or “data think” to an “object think” strategy.
16
Object Technology Principles• Abstraction
• Encapsulation (Information Hiding)
• Inheritance
• Message Communication
• Associations
• Polymorphism
• Common Methods of Organization
• Reuse
17
• AbstractionA mental ability that permits people to view real-world
problem domains with varying degrees of detail depending on the current context of the problem.
• Helps people to think about what they are doing• Functional and Data abstraction
18
• Encapsulation (Information Hiding)
A technique in which data are packaged
together with their corresponding procedures.
cakeIngredients
Directions
2 eggs 4 cups flour1 cup milk 1 cup sugaretc.......
Pre-heat oven to 350; Putmilk, eggs, and sugarin 2 quart mixing bowl...
In Object-Oriented Technology the “package” is called an OBJECT
The interface to each object is defined in such a way as to reveal as little as possible
about its inner workings
Encapsulation allows [software] changes to be reliably made with limited effort
[Gannon, Hamlet, & Mills, 1987]
One cake please!
19
• InheritanceA mechanism for expressing similarity
between things thus simplifying their
definition.
• looks• behavior• attitudes• etc...
Person
Student Faculty Staff
Inheritance
20
• Message Communication
OBJECT
OBJECT
OBJECT
OBJECT
Objects communicate via messages
21
• AssociationsThe union or connection of ideas or things.
(Objects need to interact with each other)
• same point in time
Billing StatementAdvertisement #1Advertisement #2
• under similar circumstances
crimescene
#1
crimescene
#2
crimescene
#n
22
• Polymorphism (“many forms”)
The ability to hide different implementations
behind a common interface.
The ability for two or more objects to respond
to the same request, each in its own way.
• H O = water, ice, steam (liquid, solid, vapor)
• Eating
2
versusDoor
#1Door
#2Door
#3
Door#1#2#3
• Polymorphism Two examples
PRINT0
5000
10000
15000
20000
25000
North
Sout
h
East
Wes
t
B L U E S K Y A I R L I N E SSales ReportJanuary
B L U E S K Y A I R L I N E SSales ReportFebruary
TEXT object
GRAPH object
IMAGE object
Object #1 PO object
Account object
Department object
Object #2
Object #3
Add
Add
Add
= add a line item to the PO
= increase $ Amount Balance
= hire a new employee
24
• Objects and their characteristics
• Wholes and Parts
• Groups (Classes) and Members
Classification Theory(Common Methods of Organization)
O-O Systems Analysis & Design Methodology
25
• Common Methods of Organization
People are accustomed to thinking in terms
of...
• color• price• weight• engine• options...
Objects & Attributes
• number of doors• number of wheels• number of windows• number of lights• number of bolt type 1• number of bolt type 2• etc....
Wholes and PartsGroups & Members
VANS:• light utility• utility• passenger• etc...
26
• Reuse
Varying Degrees of Reuse:
• complete or sharing
• copy, purchase or cloning
• partial or adjusting
• none
The ability to reuse objects
Software:• “Chips”• Components• Controls• Models
27
• Reuse
• Components must be reused three to five times before the costs of creating and supporting them are recovered• It costs one and a half to three times as much to create and support a single reusable component as to create a component for just one use• It costs 25% as much to use a reusable component as it does to create a new one• It takes two to three product cycles (about three years) before the benefits of reuse become significant
Software Reuse Costs and PayoffsOrenstein, D. “Code reuse: Reality doesn’t match promise”,
Computerworld, August 24, 1998, page 8.
28
O-O Systems Analysis & Design Methodology
Three Classic Systems Analysis and Design Problems:
• Data Model versus Function Model
• Analysis to Design Transition
• Maintaining Source Code
VVVVVVVVVVVV
Colorado River
North Rim of theGrand Canyon
South Rim of theGrand Canyon
Classic Software Development Problem #1:Multiple Models
DataModels
FunctionModels
SystemSystemBehaviorBehavior
VVVVVVVVVVVV
Colorado River
North Rim of theGrand Canyon
South Rim of theGrand Canyon
Classic Software Development Problem #2:Model Transformation
DesignModels
AnalysisModels
Classic Software Development Problem #3:Maintaining Source Code
Begin “Caller” Program Init x,y,z... Open (files/database) Read... Compute...
DO “Callee” with x,y,z
Update (files/database) Close (files/database) End Main Program
Procedure Callee Parameters x,y,z Compute... End Procedure
End Program
Spaghetti?
Who wrotethis code?
32
SOLUTION
Colorado River
ObjectTechnology
INTEGRATED MODEL(S)(function, data, behavior)
(analysis, design and implementation)
ROUND-TRIPENGINEERING
33
Coad’s Object-OrientedSystems Analysis & Design
Methodology*
O-O Systems Analysis & Design O-O Systems Analysis & Design MethodologyMethodology
* formerly, Coad and Yourdon
* based on Coad, P., North, D., and Mayfield M., Object Models: Strategies, Patterns, and Applications, Prentice Hall, Englewood Cliffs, NJ, 1995.
Use four object model components (Problem Domain [PD],
Human Interaction [HI], Data Management [DM], and
System Interaction [SI]) to guide and organize the work.
For each of PD, HI, DM, and SI repeat the following:
1. Identify the information system’s purpose and features
2. Select the model component’s objects and organize
them by applying patterns
3. Establish responsibilities for model component’s
objects:
• what the object knows
• who the object knows
• what the object does
4. Work out model component’s dynamics using scenarios
Coad’s Object-Oriented Methodology Standard Sequence
Variation notes for
activities 2, 3 and 4:1. They may be done
in any sequence
that is appropriate
2. One or more of them
may be omitted
3. One or more of them
may be done in parallel
4. Model components
may be done in any
order that is appropriate
ModelComponent
Problem Domain (PD)
Human Interaction (HI)
Data Management (DM)
System Interaction (SI)
Identifyobjects
andpatterns
(behavior,data)
Establishobject
responsibilities
(behavior, data,
functions)
Defineservice
scenarios(behavior
,data,
functions)
IdentifyPurpose
andFeatures
Activities
indicates that the activity has been performed for the model component
1 2 3 4
Coad’s Object-Oriented Methodology Summary
36
Iterative View of Coad’s Methodology
Establishobject
responsibilities
IdentifyPurpose and
Features
Identifyobjects and
patterns
Defineservice
scenarios
}One for each of:• System Interaction
• Data Management
• Human Interaction
• Problem Domain
37
Spiral View of Coad’s Methodology
(SI)(DM)(HI)(PD)
System InteractionData ManagementHuman InteractionProblem Domain
Defineservice
scenarios
Establishobject
responsibilities
Identifyobjects and
patterns
IdentifyPurpose and
Features
Coad’s Object Model Components
Problem Domain
Data Management System Interaction
Information System
Note: PD, HI, and SI are similar to Smalltalk programming language concept called Model-View-Controller (MVC)
Human Interaction
39
Model Components• Problem domain -- directly correspond to the
problem being modeled
• Human interaction -- provide interface between the PD objects and people
• Data management -- provide interface between PD objects and a database or file management system
• System interaction -- provide interface between PD objects and other systems or devices
40
Coad’s Object-OrientedSystems Analysis & Design
Notation*
O-O Systems Analysis & Design O-O Systems Analysis & Design MethodologyMethodology
* formerly, Coad and Yourdon
* based on Coad, P., North, D., and Mayfield M., Object Models: Strategies, Patterns, and Applications, Prentice Hall, Englewood Cliffs, NJ, 1995.
41
Subject Matter Expert & Notation
• Can you draw a stick figure of a person?
• Can you draw a picture of an automobile?
• Can you draw a picture of the space shuttle?
• Can you draw a picture of an Oopsla?
• Why not?
• Subject Matter Expert (SME)
• Notation - symbols used to communicate
42
Coad’s Object Model Notation
class with objects
model component
class
43
Coad’s Object Model Notation
MembermemberNumberfirstNamelastNametelephoneaddresscityetc...
checkOutVideocheckInVideobuyItemetc...
Attributes
Services
{{
Expanded view
of a class or
class with objects
into its three
sections:
top: Class Name
middle: attributes
bottom: services
44
Coad’s Object Model Notation
object connection messagen
n
generalization-specializationconnection
whole-partobject connection
n-n
1
n
45
The Problem Domain
Object Model
“The Big Picture”
Inventory
StoreLocationEmployee
Member
SalesTransaction RentalTransaction Vendor
PurchaseOrder
Transaction
ConcessionItemVideo Game VCR
SaleItem RentalItem
1-n
1
1-n
1n
0-1
n n
1 n
1
11-n
POLineItem1
1
1-n
SaleRentalLineItem1
1-n 1-n
1
Video Store - Problem Domain (PD) Object Model
Note: For simplification purposes, the attribute and service sections of classes and class-with-objects have been omitted from the figure.
PD Object Model with Attributes & Services
Inventory
ConcessionItemVideo Game
SaleItem RentalItem
1-n 1-nbarCodeNumberdescriptionqtyOnHandpricecosttaxCode
orderInventoryinquireAboutAvailableInventoryaddNewInventoryItemchangeInventoryItemInformationdelete/RemoveInventoryItemupdateQuantity-On-Order
quantitySoldqtyOnHand
updateQuantitySoldupdateInventoryQty-On-Hand
timesRenteddueDatememberNumber
updateRentalInformation
VCR
1 of 3
Member
SalesTransaction RentalTransaction
Transaction
1
1n
0-1n
n
1
PD Object Model with Attributes & Services
transactionNumberemployeeNumbertransactionDatetransactionTime
payForTransaction
quantitySoldpurchaseForSaleItems
memberNumberrentAnItemchecking-inRentalItem
memberNumber creditCardNumbermemberName creditCardExpireDatememeberAddress depositAmountmemberCity overdueAmountmemberStatememberZipcodememberPhone
acquireMembershipverifyMembershipupdateCreditCardInformationupdateMembershipInformationcancelMembershipupdateOverdueAmountdetermineIfDelinquent
EmployeeemployeeNumberemployeeNameemployeePhonepositionCode
updateEmployeeInformation
1
SaleRentalLineItemtransactionNumberbarCodeNumberpricesalesTax
1-n1-n
11
2 of 3
PD Object Model with Attributes & Services
StoreLocation
Vendor
PurchaseOrder
1
n
1
storeNumberaddresscitystatezipcodetelephone
provideStoreInformation
vendorNumbervendorNamevendorAddressvendorCityvendorStatevendorZipcodevendorPhonevendorFaxNumber
addNewVendorInformationchangeVendorInformationdeleteVendorprovideVendorInformation
purchaseOrderNumberpurchaseOrderDatepurchaseOrderDueDatepurchaseOrderCancelDatevendorNumber
createNewPurchaseOrderdeleteExistingPurchaseOrder
1-n
POLineItempurchaseOrderNumberbarCodeNumberquantityOrdereditemCost
1
1-n
3 of 3