Intro to SDLC

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SDLC and RelatedSDLC and Related

MethodologiesMethodologies



SDLCSDLC

SDLC stands forSDLC stands for

SystemsSystems

Development Development

LifeLife

CycleCycle

What does it mean?What does it mean?



SDLCSDLC SDLC stands forSDLC stands for

Systems Development Systems Development Life CycleLife Cycle

First, SDLC is aFirst, SDLC is a Life CycleLife Cycle..

All All systemssystems have a life cycle or a series of stageshave a life cycle or a series of stagesthey naturally undergo.they naturally undergo.

The number and name of the stages varies, but theThe number and name of the stages varies, but theprimary stages are conception,primary stages are conception, development development, maturity, maturityand decline.and decline.

TheThe systems development life cycle (SDLC)systems development life cycle (SDLC)therefore, refers to thetherefore, refers to the development development stage of thestage of thesystemsystemss life cyclelife cycle..



MethodologiesMethodologies

Is there a difference between the term SDLC and theIs there a difference between the term SDLC and theterm methodology?term methodology?

Whereas the SDLC refers to a stage all systemsWhereas the SDLC refers to a stage all systemsnaturallynaturally undergo, a methodology refers to anundergo, a methodology refers to anapproachapproach invented by humansinvented by humans to manage the eventsto manage the eventsnaturally occurring in the SDLC.naturally occurring in the SDLC.

A A methodologymethodology is, in simple terms, a set of steps,is, in simple terms, a set of steps,guidelines, activities and/or principles to follow in aguidelines, activities and/or principles to follow in aparticular situation.particular situation. Most methodologies are comprehensive, multiMost methodologies are comprehensive, multi--stepstep

approaches to systems development approaches to systems development



SDLC vs. MethodologySDLC vs. Methodology

It is confusing, but unfortunately, the termIt is confusing, but unfortunately, the termSDLC is frequently used synonymously withSDLC is frequently used synonymously with

thethe waterfallwaterfall oror traditional approachtraditional approach forfordeveloping information systems.developing information systems.

The SDLC approach The SDLC approach This approach essentially refers to a linear sequence of This approach essentially refers to a linear sequence of

stages to develop a system from planning to analysisstages to develop a system from planning to analysisto design to implementation.to design to implementation.

Stages are followed from beginning to end.Stages are followed from beginning to end.

Revisiting prior stages is not permitted.Revisiting prior stages is not permitted.



Approaches to Systems Approaches to Systems

DevelopmentDevelopment ProcessProcess--Oriented ApproachOriented Approach

Focus is onFocus is on flow, use and transformation of dataflow, use and transformation of data

in an information systemin an information system Involves creating graphical representations suchInvolves creating graphical representations suchas data flow diagrams and chartsas data flow diagrams and charts

Data are tracked from sources, throughData are tracked from sources, throughintermediate steps and to final destinationsintermediate steps and to final destinations

Natural structure of data is not specifiedNatural structure of data is not specified Disadvantage: data files are tied to specificDisadvantage: data files are tied to specific

applicationsapplications



Approaches to Systems Approaches to Systems

DevelopmentDevelopment DataData--Oriented ApproachOriented Approach

DepictsDepicts ideal organization of dataideal organization of data,,independent of where and how data areindependent of where and how data areusedused

Data model describes kinds of data andData model describes kinds of data and

business relationships among the databusiness relationships among the data Business rules depict how organizationBusiness rules depict how organization

captures and processes the datacaptures and processes the data



Approaches to Systems Development Approaches to Systems Development

Process Approach: Lets look at all of our

processes. Processes takeprecedence over data. Get theprocesses correct first. Thenwell address what data isimportant.

Data Approach: Forget the processes, letslook at the data. Data comesfirst. Get the data correct, thensee how the processes actuallyuse the data.

Which is better, the Process Approach or the Data Approach?



Databases andDatabases and

Application Independence Application Independence DatabaseDatabase

Shared collection of logically related dataShared collection of logically related data

Organized to facilitate capture, storage andOrganized to facilitate capture, storage andretrieval by multiple usersretrieval by multiple users

Centrally managedCentrally managed

Designed around subjects such as CustomersDesigned around subjects such as Customersor Suppliersor Suppliers

Application Independence Application Independence Separation of data from the applications, e.g.Separation of data from the applications, e.g.

Payroll data is part of the enterprisePayroll data is part of the enterprise--wide datawide datamodel and can be used by many systems, not just model and can be used by many systems, not just the Payroll Systemthe Payroll System



Systems DevelopmentSystems Development

Life CycleLife Cycle Every textbook has different names forEvery textbook has different names for

the stages of the SDLCthe stages of the SDLC

Usually they stages areUsually they stages are

Planning (just after Conception)Planning (just after Conception)

Analysis Analysis

DesignDesign ImplementationImplementation

Maintenance (starting Maturity)Maintenance (starting Maturity)

1.101.10




Life CycleLife Cycle This text highlights 6 distinct phases:This text highlights 6 distinct phases:

Project Identification and SelectionProject Identification and Selection

Project Initiation and PlanningProject Initiation and Planning

Analysis Analysis

DesignDesign

ImplementationImplementation

MaintenanceMaintenance



Stages of the SDLCStages of the SDLC



Phases of the SystemsPhases of the Systems

Development Life CycleDevelopment Life Cycle1.1. Project Identification and SelectionProject Identification and Selection

Two Main ActivitiesTwo Main Activities

Identification of needIdentification of need Prioritization and translation of need into aPrioritization and translation of need into a

development scheduledevelopment schedule

Helps organization to determine whether orHelps organization to determine whether ornot resources should be dedicated to a project.not resources should be dedicated to a project.

2.2. Project Initiation and PlanningProject Initiation and Planning Two ActivitiesTwo Activities

Formal preliminary investigation of the problem at Formal preliminary investigation of the problem at handhand

Presentation of reasons why system should or shouldPresentation of reasons why system should or should

not be developed by the organizationnot be developed by the organization






Life CycleLife Cycle DesignDesign

Logical DesignLogical Design

Concentrates on business aspects of the systemConcentrates on business aspects of the system Physical DesignPhysical Design

Technical specificationsTechnical specifications

ImplementationImplementation ImplementationImplementation

Hardware and software installationHardware and software installation

ProgrammingProgramming

User TrainingUser Training

DocumentationDocumentation




Life CycleLife Cycle MaintenanceMaintenance

System changed to reflect changingSystem changed to reflect changing

conditionsconditions System obsolescenceSystem obsolescence

A good way to learn the stages of the A good way to learn the stages of theSDLC is to createSDLC is to create deliverablesdeliverables (output)(output)of each stage in the process.of each stage in the process.



Alternative Approaches Alternative Approaches

PrototypingPrototyping

Building a scaledBuilding a scaled--down working version of thedown working version of the

systemsystem Advantages: Advantages:

Users are involved in designUsers are involved in design

Captures requirements in concrete formCaptures requirements in concrete form

Rapid Application Development (RAD)Rapid Application Development (RAD) Utilizes prototyping to delay producing systemUtilizes prototyping to delay producing system

design until after user requirements are cleardesign until after user requirements are clear



PrototypingPrototypingFig. 1-6




Joint Application Design (J AD)Joint Application Design (J AD)

Users, Managers and Analysts workUsers, Managers and Analysts work

together for several daystogether for several days

System requirements are reviewedSystem requirements are reviewed

Structured meetingsStructured meetings

We will see a video on this when weWe will see a video on this when wecover Chapter 7cover Chapter 7




Evolutionary or spiral methodologyEvolutionary or spiral methodologyThe *** never gets done! Different versions, always inThe *** never gets done! Different versions, always in

different stages.different stages.

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Intro to SDLC