SDLC and Related SDLC and Related MethodologiesMethodologies

Contemplative Contemplative QuestionsQuestions What are the various approaches to What are the various approaches to

developing Information Systems?developing Information Systems? Is there one best way?Is there one best way? What is the difference between What is the difference between

techniques, methodologies and techniques, methodologies and tools?tools?

What does the popular term What does the popular term “SDLC” actually mean?“SDLC” actually mean?

SDLCSDLC

SDLC stands for SDLC stands for – Systems Systems – Development Development – Life Life – CycleCycle

What does it mean?What does it mean?

SDLCSDLC

SDLC stands for SDLC stands for – Systems Development Systems Development Life CycleLife Cycle – First, SDLC is a First, SDLC is a Life CycleLife Cycle..– All All systemssystems have a life cycle or a series of stages they have a life cycle or a series of stages they

naturally undergo.  naturally undergo.  The number and name of the stages varies, but the The number and name of the stages varies, but the

primary stages are conception, primary stages are conception, developmentdevelopment, maturity , maturity and decline. and decline.

The The systems development life cycle (SDLC)systems development life cycle (SDLC) therefore, therefore, refers to the refers to the development development stage of the stage of the systemsystem’s ’s life cyclelife cycle. .

Why are we so interested in the Why are we so interested in the developmentdevelopment stage? What about conception, maturity and stage? What about conception, maturity and decline?decline?

MethodologiesMethodologies

Is there a difference between the term SDLC Is there a difference between the term SDLC and the term ‘methodology’?and the term ‘methodology’?

Whereas the SDLC refers to a stage all Whereas the SDLC refers to a stage all systems systems naturally naturally undergo, a methodology undergo, a methodology refers to an approach refers to an approach invented by humans invented by humans to to manage the events naturally occurring in the manage the events naturally occurring in the SDLC. SDLC. 

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

approaches to systems developmentapproaches to systems development– There are many methodologies out there. See There are many methodologies out there. See

www.methodology.orgwww.methodology.org . .

SDLC vs. MethodologySDLC vs. Methodology

It is confusing, but unfortunately, the It is confusing, but unfortunately, the term SDLC is frequently used term SDLC is frequently used synonymously with the synonymously with the waterfallwaterfall or or traditional approachtraditional approach for developing for developing information systems. information systems. – ““The SDLC approach”The SDLC approach”

This approach essentially refers to a linear This approach essentially refers to a linear sequence of stages to develop a system from sequence of stages to develop a system from planning to analysis to design to implementation.  planning to analysis 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 Approaches to Systems DevelopmentSystems Development Process-Oriented ApproachProcess-Oriented Approach

– Focus is on Focus is on flow, use and transformation of flow, use and transformation of data in an information systemdata in an information system

– Involves creating graphical representations Involves creating graphical representations such as data flow diagrams and chartssuch as data flow diagrams and charts

– Data are tracked from sources, through Data are tracked from sources, through intermediate 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 specific Disadvantage: data files are tied to specific

applicationsapplications

Approaches to Approaches to Systems DevelopmentSystems Development Data-Oriented ApproachData-Oriented Approach

– Depicts Depicts ideal organization of dataideal organization of data, , independent of where and how data independent of where and how data are usedare used

– Data model describes kinds of data and Data model describes kinds of data and business relationships among the databusiness relationships among the data

– Business rules depict how organization Business rules depict how organization captures and processes the datacaptures and processes the data

Approaches to Systems Approaches to Systems DevelopmentDevelopment

Process Approach:“Let’s look at all of our processes. Processes take precedence over data. Get the processes correct first. Then we’ll address what data is important.”

Data Approach:“Forget the processes, let’s look at the data. Data comes first. Get the data correct, then see how the processes actually use the data.”

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

Databases and Databases and Application Application IndependenceIndependence DatabaseDatabase

– Shared collection of logically related dataShared collection of logically related data– Organized to facilitate capture, storage and Organized to facilitate capture, storage and

retrieval by multiple usersretrieval by multiple users– Centrally managedCentrally managed– Designed around subjects such as Customers Designed around subjects such as Customers

or Suppliersor Suppliers Application IndependenceApplication Independence

– Separation of data from the applications, e.g. Separation of data from the applications, e.g. Payroll data is part of the enterprise-wide data Payroll data is part of the enterprise-wide data

model 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 Development Systems Development Life CycleLife Cycle Every textbook has different Every textbook has different

names for the stages of the SDLCnames for the stages of the SDLC– Usually they stages are Usually they stages are

Planning (just after Conception)Planning (just after Conception) AnalysisAnalysis DesignDesign ImplementationImplementation Maintenance (starting Maturity)Maintenance (starting Maturity)

1.111.11

Systems Development Systems Development Life CycleLife Cycle This text highlights 6 distinct This text highlights 6 distinct

phases:phases:– Project Identification and SelectionProject Identification and Selection– Project Initiation and PlanningProject Initiation and Planning– AnalysisAnalysis– DesignDesign– ImplementationImplementation– MaintenanceMaintenance

Stages of the SDLCStages of the SDLC

IS 421 System

s

Analysis

IS 422

Systems Design

Phases of the Systems Phases of the Systems Development Life Development Life CycleCycle1.1. Project Identification and SelectionProject Identification and Selection

– Two Main ActivitiesTwo Main Activities Identification of needIdentification of need Prioritization and translation of need into a Prioritization and translation of need into a

development scheduledevelopment schedule

– Helps organization to determine whether or Helps organization to determine whether or not 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 should Presentation of reasons why system should or should not be developed by the organizationnot be developed by the organization

Systems Development Systems Development Life CycleLife Cycle AnalysisAnalysis

– Study of current procedures and Study of current procedures and information systemsinformation systems Determine requirementsDetermine requirements

– Study current systemStudy current system– Structure requirements and eliminate Structure requirements and eliminate

redundanciesredundancies Generate alternative designsGenerate alternative designs Compare alternativesCompare alternatives Recommend best alternativeRecommend best alternative

Systems Development Systems Development 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

Systems Development Systems Development Life CycleLife Cycle MaintenanceMaintenance

System changed to reflect changing System 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 the SDLC is to create SDLC is to create deliverables deliverables (output) of each stage in the (output) of each stage in the process.process.

Alternative Alternative ApproachesApproaches PrototypingPrototyping

– Building a scaled-down working version of Building a scaled-down working version of the systemthe system

– 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 Utilizes prototyping to delay producing

system design until after user system design until after user requirements are clearrequirements are clear

PrototypingPrototypingFig. 1-6

Alternative Alternative ApproachesApproaches Joint Application Design (JAD)Joint Application Design (JAD)

– Users, Managers and Analysts work Users, 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 We will see a video on this when we cover Chapter 7we cover Chapter 7

Alternative Alternative ApproachesApproaches Evolutionary or spiral methodologyEvolutionary or spiral methodology

The *** never gets done! Different versions, The *** never gets done! Different versions, always in different stages.always in different stages.