ict117 week02 systems analysis s

8/6/2019 ICT117 Week02 Systems Analysis s

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Introduction to SystemsAnalysis and Design

Chapter 1: Dennis, Wixom, Tegarden

Plus additional material

PowerPoint Presentation for Dennis, Wixom, & Tegarden Systems Analysis and Design with UML, 3rd EditionCopyright 2009 John Wiley & Sons, Inc. All rights reserved.


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17 March, 2011 ICT117 Systems Analysis & Design, Semester 1, 2011

Includes John Wiley& Sons Inc material

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ObjectivesUnderstand why businesses use InformationSystemsUnderstand the fundamental systems developmentlife cycle and its phases.Be familiar with the different roles on the projectteam.Understand the evolution of systems development

methodologies.


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3

Business contextA business operates in two contexts;

- a public context providing its services tocustomers, clients and business partners- an internal context supporting itself as anentity within a socio-political framework

In both contexts its must do work (processes)and keep records (data)In both contexts its complexity is high


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Business as a systemThe necessary repetition and complexity areamenable to systematic proceduresThe high complexity and high volumes are

amenable to automation of systemsThus businesses and organisations usecomputerised information systems to runtheir processes and store their records


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IS as a model of the businessIf the businesss policies operate as softwareand the businesss entities and clients existas data records:Then the Information System in operation isan abstract model of the businessWe use abstract modelling techniques torepresent the analysis and design of new

Information Systems


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The IT professionalIT professionals design and build InformationSystems to model the desired operations of abusiness or organisationYou design an essential model of the solution to abusiness/organisational problemThe problem , as noted previously, is the absence ofthe desired operationsYou create the abstract business in software and

hardware based on the essential modelThe remainder of this semester explains the way it isdone the System Development Process


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The need to build new information systems orchange existing ones comes about because:- There are problems in the way in which

existing systems operate

- Changes in business circumstances

create opportunities to improve things by

doing them differently- Entirely new functionality is needed

Problems and opportunities


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The Process of SystemDevelopmentThere is no single structured problem-solvingprocess which satisfies all problem situationsThe development approach to problem-solvingmust be tailored to meet the needs of eachsituationHowever, some elements of the problem-solvingprocess can be 'standardised' to some extentThe most important element is to have some formof structure to guide each development


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The systems development process is always presentedas a life cycle (SDLC). SDLC is a generic structure toguide system developmentsA systematic and orderly approach to solving

business problems

A means of managing, directing, monitoring andcontrolling the process of system building,including:

A description of the process - steps to be followedDeliverables reports, programs, documentationMilestones - dates of completed steps or deliverables

The Systems DevelopmentProcess


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The Systems DevelopmentLife Cycle (SDLC)The SDLC is a phased progression through thesystem development process. From initiation (birth)to design to development to implementation toproduction and finally to replacement (death).Structurally the SDLC has several variations:

traditional (known as Waterfall) iterative spiralIt is often adapted to suit the business, social andpolitical needs of organisations and projects


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PROJECT TEAM ROLES

AND SKILLS


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SDLC Project team rolesManagersClientsAnalyst/Designers variousSoftware Engineers variousDatabase developersTesters


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Analyst RolesRole ResponsibilitiesBusiness Analyst Analyzing the key business aspects of the system

Identifying how the system will provide business value

Designing the new business processes and policies

Systems Analyst Identifying how technology can improve businessprocesses

Designing the new business processesDesigning the information system

Ensuring the system conforms to IS standards

InfrastructureAnalyst Ensuring the system conforms to infrastructure standardsIdentifying infrastructure changes required by the systemChange ManagementAnalyst Developing and executing a change management planDeveloping and executing a user training planProject Manager Managing the team

Developing and monitoring the project plan

Assigning resources

Serving as the primary point of contact for the project

Figure 1-14 pg 31


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Analyst activitiesGather functional requirements frominterviews, survey, observation, documentanalysis

Analyse requirements and technicalcapabilitiesDocument analysed requirementsDocument proposed design solutions


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Software Engineer RolesApplication programmerdesigns and codes/implements the businessfunctions from functional requirements

Network programmerdesigns and codes/configures network softwarefor deployment and access functions andappropriate hardware

System programmerdesigns and codes/configures OS environment andoperations control, user controls, managesmiddleware/APIs/database gateways


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Database developers - DBADatabase Analystanalyses, designs and codes/implementsdata structures in the DBMS, performancemanagement of DBMSConfigures the DBMS application eg OracleWorks with BA and SA on access designWorks with System programmers tomanage middleware access to DBMS


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SYSTEMS DEVELOPMENT

LIFE CYCLE (SDLC)


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Systems Development LifeCycle PlanningAnalysis

Design

Implementation


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SDLC: AnalysisDevelop analysis strategyGather requirementsDevelop a system proposal

The Functional Requirements Specification (FRS)Answers the questions:What should the system do for us?Where and when will it be used?


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SDLC: DesignDevelop a design strategyDesign architecture and interfacesDevelop databases and file specificationsDevelop the software program designAnswers the question:How will we build the system?


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SDLC: ImplementationConstruct the systemInstall system

Implement a training plan for the users

Establish a support planAll questions are answered so:Build the system


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Putting the SDLC TogetherEach phase consists of steps that lead tospecific deliverablesThe information system evolves through

gradual refinementOnce the IS is implemented, it may go backinto a planning phase for its next revision, afollow-on system, or maintenance releases


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Processes and DeliverablesProcess ProductPlanning

Analysis

Design

Implementation

Project Plan

System Proposal

System

Specification

New System and

Maintenance Plan

Process ProductPlanning

Analysis

Design

Implementation

Project Plan

System Proposal

System

Specification

New System and

Maintenance Plan


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SummaryAll systems development projects followessentially the same process, called thesystem development life cycle (SDLC)System development methodologies areformalized approaches to implementingSDLCsThe Unified Process that uses Object-Oriented Systems Analysis and Design(OOSAD) will be the systems developmentapproach on which we concentrate


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SYSTEMS DEVELOPMENT

METHODOLOGIES


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Systems DevelopmentMethodologiesA methodology is a formalized approach toimplementing the SDLCWell-known methodologies include:

Waterfall development

Parallel development

Spiral model of development

Rapid application development

Agile development


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Categories of MethodologiesStructured DesignWaterfall Development

Parallel DevelopmentRapid Application DevelopmentPhasedPrototyping

Throwaway PrototypingAgile DevelopmenteXtreme Programming


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TerminologyIterativesomething that is performed repeatedlyassociated with phased development andstepwise refinementIncremental

something that is developed in stagesbuild one thing then add another thing



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Structured Design 2

Parallel Development


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Rapid ApplicationDevelopment 1

Phased Development


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System Prototyping


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Throwaway Prototyping


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Iterative Development



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Spiral Model (Boehm, 1988) Original Creator: Conrad Nutschan

http://en.wikipedia.org/wiki/File:Spiral_model_%28Boehm,_1988%29.png

Boehms software

development

process


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Agile Development

Extreme Programming


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Selecting the RightMethodologyUsefulness

for

Waterfall Parallel Phased Prototyping Throwaway

Prototyping

Extreme

Programming

Unclear userrequirementsPoor Poor Good Excellent Excellent Excellent

Unfamiliartechnology Poor Poor Good Poor Excellent PoorComplexsystems

Good Good Good Poor Excellent Poor

ReliablesystemsGood Good Good Poor Excellent Good

Short timeschedulePoor Good Excellent Excellent Good Excellent

SchedulevisibilityPoor Poor Excellent Excellent Good Good


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Methodologies andTechniquesAll methodologies produce abstract modelsThe models are created with differentmodelling techniquesPhilosophical differences in methods meandifferent techniques are used3 philosophies: process-oriented, data-oriented, object-oriented


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Abstraction conceptsStructured (process and data) methods:entities are things that have data attributes,and processes represent what we do to

entitiesObject-oriented methods:objects are things that encapsulate bothdata attributes and behavioural methods.Objects do things and include the data theyneed to do those things


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Structured or OO view?Both in current useStructured is well established, many methodsOO is newer, a single methodStructured focussed on control structuresOO focussed on independent actionOO developed from a programming paradigmMost new programs are OO language based


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Next weekObject-OrientationUnified Modelling Language UMLThe Unified Process

ict117 week02 systems analysis s

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