System Analysis and Design
Introduction to System Analysis
and Design
- Dr. Mahmoud Abu-Arra
- Mr. Ahmad Al-Ghoul
Learning Objectives
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Explain systems development tools, including
modeling, prototyping, and CASE tools
Discuss and distinguish between system
development methodologies
Explain systems development methods, RAD,
JAD
Distinguish between structured analysis and
object-oriented methodology
Discuss how to use appropriate system
development method
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Introduction
 There are several tools and techniques to
build information systems, to choose the
appropriate one to build your system, you
must study them first and knows their
uses.
 Methodology is an approach, a method or
a technique for developing information
systems. The methodology defines a
method and a way of developing an
information system, guiding planners in
the desired working method.
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Systems Development Tools and
Techniques
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Systems analysts must know how to use a
variety of techniques such as modeling,
prototyping, and computer-aided systems
engineering tools to plan, design, and
implement information systems.
Systems analysts work with these tools in a
team environment, where input from users,
managers, and IT staff contributes to the
system design.
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Systems Development Tools and
Techniques
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Modeling
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Modeling produces a graphical representation of a concept or
process that system developers can analyze, test, and modify.
Modeling Used to describe and simplify an information system:
Business model or Requirements model
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Data model
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Describes the design and protocols of telecommunication links
Process model
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Describes objects, which combine data and processes.
Network model
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Describes the data structure and design.
Object model
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Describes the information that a system must provide.
Describes the logic that programmers use to write code modules
Modeling techniques, including data flow diagrams and
entity relationship diagrams, and unified modeling
language diagrams.
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Systems Development Tools and
Techniques
Prototyping
Prototyping tests system concepts and provide an
opportunity to examine input, output, and user
interface before final decisions are made.
Early working version of an information system
Pros
 Speeds up the development
process significantly
 Users interact with
Prototype very quickly
 Users can identify needed
changes and refine real
requirements
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Cons
 Important decisions might be
made too early, before
business or IT issues are
thoroughly understood
 Initial Design decisions may be
poor
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Systems Development Tools and
Techniques
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Computer-Aided Systems Engineering
(CASE) Tools
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Also called computer-aided software
engineering, is a technique that uses powerful
software, called CASE tools, to help systems
analysts develop and maintain information
systems.
Framework for systems development and
support a wide variety of design
methodologies
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Methodologies in the development of
information systems
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Bottom up
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A formalized approach to implementing the SDLC
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A series of steps and deliverables
As the base for the information system, this approach
uses the organization’s operational level.
The starting point is that, the operational level
constitutes the core of the organization.
The information requirements of the intermediate
and management levels will be supplied by the
various processing stages of operational level data.
Using this approach, studying the needs and
planning of the future system will be prepared initially
for the operational level.
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Methodologies in the development of
information systems
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Top Down
 This
approach uses the organization’s management
level as the base for the information system. The
definition of its requirements and the system goals
are dictated by the organization’s management.
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Methodologies in the development of
information systems
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Integrated Approach
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This approach combines both methods, with the aim
of benefiting from both the Bottom Up and the Top
Down approaches.
With this approach, the initial planning is carried out
by the Top Down method
The planning of the systems themselves (subsystems) is performed using the Bottom Up approach
in order to ensure proper planning, based on
operational level requirements.
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Methodologies in the development of information
systems
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Structured Analysis
“Structured analysis is a set of techniques and graphical tools that
allow the analyst to develop a new kind of system specification that
are easily understandable to the user. Analysts work primarily with
their wits, pencil and paper.” [Kendall 1996]
Uses a set of process models to describe a system graphically
The availability of CASE tools in the 1990s enabled analysts to
develop and modify the graphical SASD models.
[1]
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Methodologies in the development of
information systems
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Object-oriented (O-O) analysis
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O-O analysis combines data & processes into things
called objects
O-O analysis uses object models to represent data
and behavior, and to show how objects affect other
objects
By describing the objects (data) and methods
(processes) needed to support business operation, a
system developer can design reusable components
that allow faster system implementation and
decreased development cost
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Methodologies in the development of
information systems
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Object-oriented (O-O) analysis
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objects combine data and processes. Object are the end
product of object-oriented analysis. Object is a member of a
class
Class is a collection of similar objects
Objects possess characteristics called properties
Properties inherits from the object class or possesses on its own
In O-O design, built-in processes called methods can change an
object’s properties
Object can send information to anther object by using a
message
A message requests specific behavior or information from
another object
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Methodologies in the development of
information systems
Object-oriented (O-O) analysis
[1]
The PERSON class includes INSTRUCTOR and STUDENT
objects, which have their own properties and inherited
properties.
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Methodologies in the development of
information systems
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Joint Application Development and Rapid
Application Development
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JAD – The basic idea behind JAD is to bring structure
to the requirements determination phase of analysis
and to the reviews that occur as a part of design.
Team based fact finding
Users, Managers and Analysts work together for
several days
System requirements are reviewed
Structured meetings
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Methodologies in the development of
information systems
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RAD – created to radically decrease the time needed
to design and implement information systems.
RAD relies on extensive user involvement.
Incorporate special techniques and tools:
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CASE tools
JAD sessions
Fourth generation/visualization programming
languages
Code generators
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Methodologies in the development of
information systems
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There are many other methods
A systems analyst should
understand the alternative
methodologies and their individual
strengths and weaknesses.
how you will choose the suitable
method?
Selecting a methodology is not
simple, as no one methodology is
always best.
Many organizations have their
own standards.
We will discuss this topic in more
detail in the analysis chapter
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Sequence Summary
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In this Sequence we have
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Discussed the various systems development
methods, tools, and techniques
Distinguished between structured analysis and
object-oriented methodology
Discussed how to use appropriate system
development method
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Reference
[1] System Analysis and Design, Sixth Edition
Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt ,
Publisher: SHELLY CASHMAN SEWIES.
[2] Modern Systems Analysis and Design Third Edition
Authors: Jeffrey A. Hoffer , Joey F. George, Joseph S. Valacich
Publisher: prentice hall
[3] System Analysis and Design, 3rd Edition
Authors: Dennis, Wixom, & Roth
Publisher: John Wiley & sons
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