MANAGING
INFORMATION
TECHNOLOGY
FIFTH EDITION
CHAPTER 9 (part b)
BASIC INFORMATION
SYSTEMS CONCEPTS
E. Wainright Martin  Carol V. Brown  Daniel W. DeHayes
Jeffrey A. Hoffer  William C. Perkins
© 2005 Pearson Prentice-Hall
Chapter 9 - 2
Boxes
Major modules
Cylinders
Databases
Arrows
Flow of data
Figure 9.10 Physical Model of a System
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Tools for the As-Is Model
 Must identify existing processes, external
participants, other databases or applications,
and inputs and outputs
 Tools used:



Procedures, policies, manuals, forms, reports
Other documentation
Group interviews
© 2005 Pearson Prentice-Hall
Chapter 9 - 3
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Tools for the As-Is Model
Context diagram – positions the system as a whole with
regard to other entities and activities with which it interacts
Work process flow diagram – identifies the existing
information sources, information sources that are updated,
order in which steps occur, and some of the dependencies
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Chapter 9 - 4
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Tools for the As-Is Model
© 2005 Pearson Prentice-Hall
Chapter 9 - 5
Figure 9.11 Context Diagram
for Accounts Payable
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© 2005 Pearson Prentice-Hall
Chapter 9 - 6
Figure 9.12 Work Process Flow Diagram
for Accounts Payable
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Tools for the
Logical To-Be Model
 High-level model of a nonexistent new system
 Identifies processes and data
 Does not identify who does activity, where
accomplished, or type of hardware or software
 Describes “what” rather than “how”
 Most closely associated with data flow diagrams
(DFDs)
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Chapter 9 - 7
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Tools for the
Logical To-Be Model
© 2005 Pearson Prentice-Hall
Chapter 9 - 8
Figure 9.13(A) Top-Level DFD
for Accounts Payable System
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Data Flow
Processes
External Entity
Data Store
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Chapter 9 - 9
Figure 9.13(A) Top-Level DFD
for Accounts Payable System
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Tools for the
Logical To-Be Model
 Process of creating a DFD:

Identify entities that supply or use system information

Distinguish processes from data they use or produce

Explicate business rules that affect transformation of
data to information

Identify logical relationships

Pinpoint duplicate storage and movement of data
© 2005 Pearson Prentice-Hall
Chapter 9 - 10
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Lower-level explosion DFD for Process 1.0
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Chapter 9 - 11
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Note process
numbering scheme
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Chapter 9 - 12
Figure 9.13(B) Second-Level DFD
for Accounts Payable System
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Tools for the
Logical To-Be Model
 More logical modeling required after DFDs
 Need to define system’s data elements and
relationships:

Data dictionary/directory (DD/D) used to define data
elements

Entity-relationship diagram (ERD) used to define
relationships between entities
© 2005 Pearson Prentice-Hall
Chapter 9 - 13
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© 2005 Pearson Prentice-Hall
Chapter 9 - 14
Figure 9.14 Data Dictionary Sample Entry
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Tools for the
Logical To-Be Model
© 2005 Pearson Prentice-Hall
Chapter 9 - 15
Figure 9.15 Entity-Relationship Diagram
for Invoice and PO
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Relational Database Terminology
© 2005 Pearson Prentice-Hall
Chapter 9 - 16
Figure 9.16 Key Terms
for Logical Data Modeling
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Tools for Documenting
the Physical To-Be System
 Tools for physical design represent how:


processes and data stores partitioned

program control handled

database organized
Tools include:

Program structure chart

Database design

System interface layouts
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Chapter 9 - 17
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Program Structure Chart
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Chapter 9 - 18
Figure 9.17 Program Structure Chart
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Database Design
(data relationships)
(Screen shot reprinted with permission from Microsoft Corporation)
© 2005 Pearson Prentice-Hall
Chapter 9 - 19
Figure 9.18 Relationships for Data Elements
in Accounts Payable
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System Interface
Input Layout Form
(Screen shot reprinted with permission from Microsoft Corporation)
© 2005 Pearson Prentice-Hall
Chapter 9 - 20
Figure 9.19 Input Form Layout
for Vendor Invoice
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Output Report Layout
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Chapter 9 - 21
Figure 9.20 Check Register Report Layout
with Sample Data
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PROCESSES AND TECHNIQUES TO
DELIVER INFORMATION SYSTEMS
Object-Oriented Techniques
 Object approach well suited for client/server
applications, graphical interfaces, and
multimedia data
 Primary advantage is ability to reuse objects
programmed by others
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Chapter 9 - 22
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PROCESSES AND TECHNIQUES TO
DELIVER INFORMATION SYSTEMS
Object-Oriented Techniques
© 2005 Pearson Prentice-Hall
Chapter 9 - 23
Figure 9.21 The Promise
of Object-Oriented Approaches
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PROCESSES AND TECHNIQUES TO
DELIVER INFORMATION SYSTEMS
Core Concepts
 Object
 Encapsulation
 Inheritance
Objects communicate with each other through messages
that specify what should be done, not how it should be done
© 2005 Pearson Prentice-Hall
Chapter 9 - 24
Figure 9.22 Message Passing
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PROCESSES AND TECHNIQUES TO
DELIVER INFORMATION SYSTEMS
Unified Modeling Language (UML)
For O-O Modeling



UML is standardization for O-O analysis and design
modeling techniques and notations
UML diagrams:
 Use-case diagrams
 Extended relationship use-case diagram
 Sequence diagram
 Class diagram
Logical modeling begins with use-cases – diagrams and
text forms
© 2005 Pearson Prentice-Hall
Chapter 9 - 25
Figure 9.22 Message Passing
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Use Case Diagram
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Chapter 9 - 26
Figure 9.23 Use Case Diagram
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Use Case – Text Form
© 2005 Pearson Prentice-Hall
Chapter 9 - 27
Figure 9.24 Become Member Use Case
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INFORMATION SYSTEMS
CONTROLS TO MINIMIZE
BUSINESS RISKS
 Common system security risks:

Human error

Criminal acts

Due to staffing changes and project management
deficiencies

Natural disasters
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Chapter 9 - 28
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INFORMATION SYSTEMS
CONTROLS TO MINIMIZE
BUSINESS RISKS
Types of Control Mechanisms
 Management policies
 Operating procedures
 Auditing function
© 2005 Pearson Prentice-Hall
Chapter 9 - 29
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INFORMATION SYSTEMS
CONTROLS TO MINIMIZE
BUSINESS RISKS
Types of Control Mechanisms
 Controls built into the information system itself:

To maintain data integrity

Allow only authorized access

Ensure proper system operation

Protect against malfunctions, power outages, and
disasters
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Chapter 9 - 30
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INFORMATION SYSTEMS
CONTROLS TO MINIMIZE
BUSINESS RISKS
Types of Control Mechanisms
 IS Organization
 Backup
power
supplies
 Network access
control
 Firewall protection
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Chapter 9 - 31
 Business Organization
 Ensure
accurate data
entry and handling
 Identify procedural
errors
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INFORMATION SYSTEMS
CONTROLS TO MINIMIZE
BUSINESS RISKS
Types of Control Mechanisms
© 2005 Pearson Prentice-Hall
Chapter 9 - 32
Figure 9.26 Pre- and Post-Installation Controls
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