Systems Analysis
and Design II
Describing Methodologies
PART I
SDLC and Rapid Application
Development*
Learning Objectives
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Describe the Traditional Methodologies
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Systems Development Life Cycle (SDLC).
Waterfall Model (SDLC Waterfall)
Enhanced Waterfall Model
Explain Rapid Application Methodologies
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Chapter 1
Prototyping,
Joint Application Development (JAD)
Rapid Application Development (RAD),
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Approaches to Systems Analysis
and Design
Chapter 1
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A: Traditional Methodologies.
1. Systems Development Life Cycle
(SDLC)
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Traditional methodology used to develop,
maintain, and replace information systems.
Phases in SDLC:
 Planning
 Analysis
 Design
 Implementation
 Maintenance
Chapter 1
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Standard and Evolutionary Views
of SDLC
Chapter 1
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Systems Development Life Cycle
(SDLC) (Cont.)
Planning – an organization’s total
information system needs are identified,
analyzed, prioritized, and arranged.
 Analysis – system requirements are
studied and structured.
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Chapter 1
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Systems Development Life Cycle
(SDLC) (Cont.)
Design – a description of the
recommended solution is converted into
logical and then physical system
specifications.
 Logical design – all functional features of
the system chosen for development in
analysis are described independently of
any computer platform.
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Chapter 1
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Systems Development Life Cycle
(SDLC) (Cont.)

Physical design – the logical
specifications of the system from logical
design are transformed into the
technology-specific details from which all
programming and system construction can
be accomplished.
Chapter 1
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Systems Development Life Cycle
(SDLC) (Cont.)
Implementation – the information system
is coded, tested, installed and supported in
the organization.
 Maintenance – an information system is
systematically repaired and improved.
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Chapter 1
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Chapter 1
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2. Traditional Waterfall SDLC
•The same as
previously discussed
SDLC
•Only unique feature
is ---•One phase begins
when another
completes, little
backtracking and
looping
Chapter 1
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Problems with Waterfall Approach
System requirements “locked in” after
being determined (can't change).
 Limited user involvement (only in
requirements phase).
 Too much focus on milestone deadlines of
SDLC phases to the detriment of sound
development practices.

Chapter 1
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3. Enhanced Waterfall SDLC
Planning
Analysis
Logical
Design
Physical
Design
Enhanced
Waterfall SDCL
allows flexibility in
development
process
specifically to
minimize errors
and producing a
required system.
Implementation
Maintenance
Chapter 1
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B: Rapid Application Methodologies.
 Effort
to improve systems analysis
and design process, several different
approaches have been developed.
 Rapid Application methodologies
share two key advantages
Chapter 1
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B: Rapid Application
Methodologies. (Cont..)
1. Prototyping
 An iterative process of system
development in which requirements are
converted to a working system that is
continually revised through close
collaboration between analyst and users
Chapter 1
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Prototyping (Cont.)

Prototype addresses some of the problem
of traditional systems analysis; in
particular
 The
complaints that users only see their
information system at implementation
 Too late to make changes
 Analyst to experiment on the users instead of
the system.
 The first version of the system is also the final
version, etc
Chapter 1
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Prototyping (Cont.)
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In information systems there are different kinds
of prototype with different objectives.
The most common use of prototype is to
examine area where the user and analyst are
unsure of the requirement and feel they need
tease out and explore the real needs by showing
and amending a physical approximation of a
system.
There are two types of prototypes
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Chapter 1
A throwaway (or expendable) prototype
An evolutionary prototype.
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Prototyping (Cont.)
Chapter 1
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Prototyping (Cont.)
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Identify Problem
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stage of minimally indentifying and describing
a problem.
The application area is not well defined and
the organization in not familiar with the
technology.
Develop Prototype
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Chapter 1
Construct a prototype for evaluation by users;
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Prototyping (Cont.)
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Implement and Use Prototype
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A process of indentifying true organizational and user
need for the problem/opportunity at hand;
Revise and Enhance Prototype
A
set of evaluation and prototype modification
stage;

Convert to Operational System
 Using
 Tools
Chapter 1
the prototype as an operational system.
for Prototyping are CASE tools
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Prototyping (Cont.)

Some advantages of Prototyping
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Chapter 1
Reduces development time.
Reduces development costs.
Requires user involvement.
Developers receive quantifiable user feedback.
Facilitates system implementation since users know
what to expect.
Results in higher user satisfaction.
Exposes developers to potential future system
enhancements.
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Prototyping (Cont.)
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Some Disadvantages of Prototyping
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Chapter 1
Can lead to insufficient analysis.
Users expect the performance of the ultimate system
to be the same as the prototype.
Developers can become too attached to their
prototypes
Can cause systems to be left unfinished and/or
implemented before they are ready.
Sometimes leads to incomplete documentation.
If sophisticated software prototypes (4th GL or CASE
Tools) are employed, the time saving benefit of
prototyping can be lost.
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Summary

In this Lecture you have learned
 The
differences between Traditional and
Rapid Systems Methodologies
 Types and steps that can be adapted for
Traditional
SDLC
 Waterfall SDLC
 Rapid Application Methodologies

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Chapter 1
Prototyping (1)
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