Unit 2 lEC 1

8/4/2019 Unit 2 lEC 1

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Unit 2: SystemsAnalysis

Lecture 1

Learning hours: 60NQF level 4: BTEC Higher National H2

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8/4/2019 Unit 2 lEC 1


Description of unit• This unit will provide learners with a detailed

insight into the systems analysis life cycle • modeling tools and techniques , testing

procedures and the need for systemsevaluation.

• This unit will examine the requirements ofanalysis for both commercial and technicalapplications.

• It will also introduce the data and functionalmodeling techniques which learners can beexpected to use.

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Summary of learning outcomes

• To achieve this unit a learner must : – 1 Understand the systems analysis life

cycle – 2 Use systems analysis tools and

techniques – 3 Perform a system investigation

– 4 Investigate functional and data modeling .

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1.systems analysis life cycle

• Systems lifecycle : – the stages of a chosen cycle

• Feasibility• Analysis• Specification• Design,• Detailed• Design,• Code• Unit test• Integrate and test• maintenance), the purpose of

• each stage, differentiation between validation and verification• Evaluation of other lifecycle models : comparison of a chosen modelwith other models (eg prototyping, dynamic systems development,waterfall, spiral, rapid applications design)

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• What is System Analysis & Design • What is Systems Development Life Cycle

– History of SDLS – Waterfall

• Evaluation of lifecycle models – Prototyping

– Dynamic systems development – Spiral – Rapid applications design

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System Analysis & Design

• System Analysis & Design involves – Study the present system and – Sketch a blueprint

• To develop a new system or• To modify the present system

• First introduced by Industrial Engineers

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EVOLUTION

• In 1950s – Batch systems

• In 1960s

– Change of technology

– Debugging, maintenance & reliability

– Structured programming

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EVOLUTION (Cont.,)

• In 1970s – Brilliant systems for wrong problem – Reasons

• Lack of user involvement• Poor user-analyst communication• Tendency to move into physical design too

soon – Structured System Analysis & Design

• Framework• Set of techniques• Top down approach• Customized solutions

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EVOLUTION (Cont.,)

• In 1990s

– Release of SSADM version 4+

– Object Oriented Methodology• Makes systems much closer to real world

• Requires a higher level of expertise

• Unified Modeling Language (UML)

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SYSTEMS ANALYST

• Person who plays the main role in SAD• Requires four skills to succeed

– Analytical – Technical – Managerial – Interpersonal

• Should undertake to follow code ofprofessional conduct and code of ethics

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Waterfall

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Requirement Analysis &Definition

• Requirement Analysis & Definition:

All possible requirements of the system to be developed arecaptured in this phase. Requirements are set of functionalities andconstraints that the end-user (who will be using the system) expectsfrom the system. The requirements are gathered from the end-userby consultation, these requirements are analyzed for their validityand the possibility of incorporating the requirements in the system tobe development is also studied. Finally, a Requirement Specificationdocument is created which serves the purpose of guideline for thenext phase of the model.

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System & Software DesignBefore a starting for actual coding, it is highlyimportant to understand what we are going tocreate and what it should look like? Therequirement specifications from first phase are

studied in this phase and system design isprepared. System Design helps in specifyinghardware and system requirements and alsohelps in defining overall system architecture.The system design specifications serve as inputfor the next phase of the model.

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Implementation & Unit Testing

On receiving system design documents, thework is divided in modules/units and actualcoding is started. The system is first developedin small programs called units, which areintegrated in the next phase. Each unit isdeveloped and tested for its functionality; this isreferred to as Unit Testing. Unit testing mainlyverifies if the modules/units meet theirspecifications.

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Integration & System Testing

As specified above, the system is first divided inunits which are developed and tested for theirfunctionalities. These units are integrated into acomplete system during Integration phase andtested to check if all modules/units coordinatebetween each other and the system as a wholebehaves as per the specifications. Aftersuccessfully testing the software, it is deliveredto the customer.

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Operations & MaintenanceThis phase of "The Waterfall Model" is virtuallynever ending phase (Very long). Generally,problems with the system developed (which arenot found during the development life cycle)

come up after its practical use starts, so theissues related to the system are solved afterdeployment of the system. Not all the problemscome in picture directly but they arise time totime and needs to be solved; hence this processis referred as Maintenance.

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INTRODUCTION to SADM

– One of the Structured Methods – Introduced in early 1980s – Adopted as a British standard – An examinable qualification to be a systems

consultant – Covers most of the SDLC from Feasibility

Study to System Design – Well suited for database-oriented systems

where requirements are clear & stable

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INTRODUCTION (Cont.,)• SADM

– Framework & set of techniques for SAD – Higher degree of user involvement – Three different but independent perspectives

• Functional• Data• Event

– A top-down approach – Separation of Logical & Physical models – Systems documentation

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INTRODUCTION (Cont.,)

• SADM is NOT – A project estimation & control method – A mechanism for generating perfect systems – A self-contained methodology for SAD

• Other essential skills – Facts gathering – Process & procedure design – GUI & report design – Hardware & software selection – Creative thinking

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SCOPE OF SADM

Feasibility Study

System Analysis

System Design

Implementation

Maintenance

Strategy Planning

Module 0 - Feasibility StudyModule 1 - Requirements Analysis

Module 2 - Requirement SpecificationModule 3 - Logical System SpecificationModule 4 - Physical Design

SSADM

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STAGES IN SADM

Stage 0 - Feasibility Study

Stage 1 - Investigation of Current Environment

Stage 3 - Definition of Requirements

Stage 4 - TSOs

Stage 6 - Physical Design

Stage 2 – BSOs

Stage 5 - Logical Design

Module 0

Module 1

Module 2

Module 3

Module 4

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Summary of learning outcomes

• To achieve this unit a learner must : – 1 Understand the systems analysis life

cycle – 2 Use systems analysis tools and

techniques – 3 Perform a system investigation

– 4 Investigate functional and data modeling .

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Assessment criteria for pass

To achieve each outcome a student must demonstratethe ability to

• Identify the functions and purpose of eachstage of a systems life cycle• Provide evidence to support an

understanding of the lifecycle• Compare different life cycle models

Unit 2 lEC 1

Documents

Transcript of Unit 2 lEC 1