Introduction to Objects
MIS 3501: Management Information Systems
Paul Weinberg
weinberg@temple.edu
Adapted from material by David Schuff, and Paul Weinberg
Complex technology projects are
difficult to manage and often fail
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Complex projects are difficult to manage
and frequently fail
The problem is most frequently handled by
breaking the project into small pieces.
(Decomposition)
Decomposition is used when analyzing a
business but also when developing
systems.
There are two primary methods of
decomposition
Decomposition

Process decomposition
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Processes are made up of smaller
processes, which are made up of smaller
processes, etc.
Visualized in class through Data Flow
Diagrams (DFDs) and flowcharts
Component (or object) decomposition
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Objects are collections of processes and
data associated with the processes
Visualized through the Universal Modeling
Language (UML)
How decomposition is used
Each piece can be developed
independently by separate teams.
 The pieces are tested independently
(unit testing), and then assembled to
test larger units (system testing).
 The assembly process continues until
the entire system is ready to be tested
by the user (acceptance testing).
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Process vs Component
(Object) Decomposition
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Process
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Processes executed in
order following a process
flow.
Processes use
subprocesses at defined
points.
Normally the operation of a
subprocess is not hidden
from the outside world.
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Component
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Processes executed
when a component
receives a message from
another component
Processes can be
executed when an event
occurs
Normally the operations
of a component are
hidden from the outside
world.
There is a mechanism for
creating families of
standardized
components
Process vs Component
(Object Decomposition)
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Process
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To use a process you
need to know the items in
a DFD
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Component
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• The messages to send to
the component
• The messages it returns
• What it does
• Input
• Output
• What it does
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There is no mechanism
for standardizing groups
of processes
Generally organized in a
hierarchy
To use a component, you
need to know
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There is a mechanism for
creating families of standard
components assuring that
they all operate in a similar
fashion
Generally organized by use.
(Which components use
other components)
Decomposition Examples

Process
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IRS forms
Cookbooks
Traditional (green
screen) computer
applications
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Component
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Airline reservation
systems
Windows applications
and visual
components
Company franchises
Service applications
(like ATM networks)
Personal Computer
and TV construction
Methods and Objects
Methods are mechanisms for implementing
systems through process decomposition.
Software objects are mechanisms for implementing
systems by breaking them into components.
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Most modern programming languages are objectoriented
• Java, C++, C#, etc.
You have been using objects in this
course . . .
TextBox
Class
txtIncome
Object
txtTax
Object
Properties
Text
Location
ReadOnly
Size
900
123,83
false
100,20
$18.00
123,120
true
100,20
Methods
Hide()
Show()
Paste()
Using Object Technology
Create or obtain object classes
 An object class is a template (or pattern)
from which an object is created
 Create (instantiate) one or more objects
from the class
 Assemble the objects if necessary into larger
objects
 Use the objects
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Objects in computer programs are
collections of data and procedures
o The procedures affect the data and
determine what the object does
o The data items in an object are sometimes
called properties
o The procedures may be called functions or
methods.
o Functions and methods may respond to
events
Real World Objects - McDonalds
Class Definition
McDonalds Standards:
Properties and data
Grill specifications
Financial goals
General ledger reporting data
Bread inventory
Methods
Cook a Big Mac
Keep a Big Mac warm
Set financial goals
Report monthly financials
Standards, processes,
and structure
Shinjuku Station,
Tokyo, McDonalds
30th Street Station,
Philadelphia, McDonalds
Objects
The McDonalds Example Encapsulation
McDonalds
Parent
Monthly
Financial
results
30th Street Station,
Philadelphia, McDonalds
[local records]
Shinjuku Station,
Tokyo, McDonalds
[local records]
Object-Oriented Design
Account
Object name:
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Encapsulation
Object Hierarchies
Inheritance
Polymorphism
Object attributes/properties:
Object functions/methods:
Number
Beginning Balance
Name
Ending Balance
Client
Current Balance
Manager
Interest Rate
Date Opened
Open Acct
Close Acct
Accept Deposits
Withdrawal
Pay Interest
Savings
Interest Rate
Monthly Fees
Checking
Lowest Balance in Month
Bad Check Charges
Authorized Signature
Pay Interest
Compute Charges
Print Quarterly Statement
Budget Saver
Print Monthly Statement
Send Bad Check Notice
Pay Interest
Money Market
Volume
Senior Citizen
CD
Fixed Fee
Student
So far . . .
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We have used pre-defined classes which generate visible
objects
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Forms
Buttons
TextBoxes
ListBoxes
The objects are created for you when you drag the class
name to the design area from the toolbox.
Some of the objects contain other objects (Forms
contain Buttons, TextBoxes, etc)
You use the objects following the object name with the
property or method. For example:
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txtTax.Text
txtTax.hide()
New concepts
Creating classes
 Classes which create non-visible
objects
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Accounts
 Airline Reservations
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Later:
Objects in Arrays and ArrayLists
 Classes which inherit from other other
classes.
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Alice Exercise
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Alice is a
programming system
from Carnegie Mellon
University for creating
interactive 3-D worlds
Alice was develop to
introduce people to
object technology.
Examples of classes in Alice include: People,
buildings, vehicles, animals
Alice
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Objects created from Alice classes have
properties and methods
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If you want to know more about Alice . . .
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You can get your own (free) copy at
www.alice.org
A book is available but not required for this
course . . .
• Learning to Program with Alice (Wanda Dunn, Stephen
Cooper, Randy Pausch) --- Pearson, Prentice Hall

Free tutorials are available at
www.dickbaldwin.com/tocalice.htm and other
sites.