SYSTEM ANALYS

IS AND

DESIGN

S A F A A S. Y

. DA L L O U L

INTRODUCTION

UNIT 1: INTRODUCTIONIntroductionThe SDLC Planning Analysis Design ImplementationDevelopment

MethodologiesStructured Design Waterfall methodology Parallel Development

Rapid Application Development (RAD)

Phased Development Prototyping Throwaway Prototyping

Agile DevelopmentExtreme ProgrammingSelecting the

appropriate methodology

Exercises

INTRODUCTIO

NThe systems development life cycle (SDLC) is the process of understanding how an information system (IS) can support business needs, designing the system, building it, and delivering it to users.

SDLC

SDLC Phases

Planning Analysis Design Implementation

SDLC PHASES

PHASE ONE: PLANNING

Steps:  Identify opportunity Analysis feasibility Develop work plan Staff Project Control and direct

project

Focus: Why build this system? How to structure the project?

 Primary Outputs:  • System Request with Feasibility Study.• Project Plan 

PHASE TWO: ANALYSIS

Steps:

Develop analysis strategy

Determine business requirements

Create use cases Model processes Model data

Focus: Who, what, where, and when for this system?

 Primary Outputs:

• System proposal

PHASE THREE: DESIGN

Steps:

Design physical system

Design architecture Design interface Design programs Design database and

files

Focus: How will system work? Primary Outputs:

• System specification

PHASE FOUR: IMPLEMENTATION

Steps:

Construct System Install system Maintain system Post-implementation

Focus: Delivery and support of completed system Primary Outputs:

• Installed system

TRUE OR FALSESystem request is a primary output of design ( )

System specification with feasibility study is a primary output of planning ( )

System proposal is a primary output of analysis ( )

Installed system is a primary output of implementation ( )

TRUE OR FALSESystem request with feasibility study is a primary output of

design ( F )

System specification is a primary output of planning ( F )

System proposal is a primary output of analysis ( T )

Installed system is a primary output of implementation ( T )

UNIT 1: INTRODUCTIONIntroductionThe SDLC Planning Analysis Design ImplementationDevelopment

MethodologiesStructured Design Waterfall methodology Parallel Development

Rapid Application Development (RAD)

Phased Development Prototyping Throwaway Prototyping

Agile Development Extreme Programming

Selecting the appropriate methodology

Exercises

DEVELO

PMENT

METHODOLO

GIESA methodology is a formalized approach to implementing the SDLC (i.e., it is a list of steps and deliverables).

The methodology will vary depending on whether the emphasis is on businesses processes or on the data that supports the business

Structu

red Des

ign, RAD, A

gile

DEVELO

PMENT

METHODOLO

GIES

Process-centered methodologies focus first on defining the activities associated with the system

 Data-centered methodologies focus first on defining the contents of the data storage containers and how the contents are organized

Structu

red Des

ign, RAD, A

gile

DEVELO

PMENT

METHODOLO

GIES

Object-oriented methodologies attempt to balance the focus between processes and data. Object-oriented methodologies utilize the Unified Modeling Language (UML) to describe the system concept as a collection of objects incorporating both data and processes.

Structu

red Des

ign, RAD, A

gile

EXAMPLE

Payrol

l Sys

tem

The open-ended rectangles in the diagram represent data storage containers

The rounded rectangles in the diagram represent activities performed

STRUCTURED DESIGN

• Structured design methodologies adopt a formal step-by-step approach to the SDLC that moves logically from one phase to the next

• Traditional structured design uses one set of diagrams to represent the processes and a separate set of diagrams to represent data .

• This category includes two methodologies waterfall and parallel methodologies.

STRUCTURED DESIGNWaterfall Methodology

With waterfall development-based methodologies, the analysts and users proceed sequentially from one phase to the next

STRUCTURED DESIGNWaterfall

Methodology

STRUCTURED DESIGNWaterfall

Methodology

Advantages: 

System requirements are identified long before programming begins

Changes to the requirements are minimized as the project proceeds

STRUCTURED DESIGN

Disadvantages: 

The design must be completely specified before programming begins 

A long time elapses between the completion of the system proposal in the analysis phase and the delivery of the system

Waterfall Methodology

STRUCTURED DESIGNParallel

Methodology

STRUCTURED DESIGNParallel Methodology

This methodology attempts to address the long time interval between the analysis phase and the delivery of the system A general design for the entire system is performed and then the project is divided into a series of distinct subprojects.

RAPID APPLICATION DEVELOPMENT (RAD)• RAD-based methodologies adjust the SDLC phases to

get some part of the system developed quickly and into the hands of the users.

• Most RAD-based methodologies recommend that analysts use computer tools to speed up the analysis, design, and implementation phases, such as CASE (computer-aided software engineering) tools.

RAPID APPLICATION DEVELOPMENT (RAD)• One possible subtle problem with RAD-based

methodologies is managing user expectations

• In this category we will study three different methodologies Phased development, Prototyping development and Throwaway development methodologies

RAPID APPLICATION DEVELOPMENT (RAD)Phased Development

The phased development-based methodologies break the overall system into a series of versions that are developed sequentially Phased development-based methodologies have the advantage of quickly getting a useful system into the hands of the users The major drawback to phased development is that users begin to work with systems that are intentionally incomplete

RAPID APPLICATION DEVELOPMENT (RAD)Phased

Development

RAPID APPLICATION DEVELOPMENT (RAD)Prototyping

Prototyping-based methodologies perform the analysis, design and implementation phases concurrently. All three phases are performed repeatedly in a cycle until the system is completed. A prototype is a smaller version of the system with a minimal amount of features

RAPID APPLICATION DEVELOPMENT (RAD)Prototyping

RAPID APPLICATION DEVELOPMENT (RAD)Prototypi

ng

Advantage: Provides a system for the users to interact with, even if it is not initially ready for use. Disadvantage: Often the prototype undergoes such significant changes that many initial design decisions prove to be poor ones.

RAPID APPLICATION DEVELOPMENT (RAD)Throwaway Prototyping

Throwaway prototyping methodologies are similar to prototyping based methodologies.

The main difference is that throwaway prototyping IS completed during a different point in the SDLC. Has relatively thorough analysis phase.

RAPID APPLICATION DEVELOPMENT (RAD)Throwaway

Prototyping

AGILE DEVELOPMENT

• This category focuses on streamlining the SDLC by eliminating much of the modeling and documentation overhead and the time spent on those tasks.

• Projects emphasize simple, iterative application development.

• This category uses extreme programming, which is described next

AGILE DEVELOPMENTExtreme Programming

Is founded on four core values: communication, simplicity, feedback, and courage.

 

Key principles of XP include: 

Continuous testing 

Simple coding 

Close interaction with the end users to build systems very quickly

AGILE DEVELOPMENTExtreme

Programming

UNIT 1: INTRODUCTIONIntroductionThe SDLC Planning Analysis Design ImplementationDevelopment

MethodologiesStructured Design Waterfall methodology Parallel Development

Rapid Application Development (RAD)

Phased Development Prototyping Throwaway Prototyping

Agile Development Extreme Programming

Selecting the appropriate methodology

Exercises

SELECTIN

G APPROPR

IATE

METHODOLO

GYSelecting a methodology is not simple, as no one methodology is always best. Many organizations have their own standards. The next figure summarizes some important methodology selection criteria

Exerc

ises

Ability to Develop systems

Structured Methodologies

RAD MethodologiesAgile

Methodologies

Waterfall

ParallelPhase

dPrototyp

ingThrowaway Prototyping

XP

With Unclear User Requirements

Poor Poor Good Excellent Excellent Excellent

With Unfamiliar Technology

Poor Poor Good Poor Excellent Poor

That are Complex Good Good Good Poor Excellent Poor

That are reliable Good Good Good Poor Excellent Good

With a short Time Schedule

Poor Good Excellent

Excellent Good Excellent

With Schedule Visibility Poor Poor Excellent

excellent Good Good

EXERCISES☺Suppose you are a project manager using the

waterfall development methodology on a large and complex project. Your manager has just read the latest article in Computerworld that advocates replacing the waterfall methodology with prototyping and comes to your office requesting you to switch What do you say?

☺Think about your ideal analyst position. Write a newspaper ad to hire someone for that position. What requirements would the job have? What skills and experience would be required? How would applicants demonstrate that they have the appropriate skills and experience?

SAFAA S.Y. DALLO

UL

S A F A A D A L L O U L . WO R D P R E S S . C

O M

Thank You