Btec National - IT SYSTEMS ANALYSIS AND DESIGN 1 IT Systems Analysis & Design Introduction into IT Systems Analysis and Design

Btec National - IT SYSTEMS ANALYSBtec National - IT SYSTEMS ANALYSIS AND DESIGNIS AND DESIGN

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IT Systems Analysis & IT Systems Analysis & DesignDesign

Introduction into IT Systems Introduction into IT Systems Analysis and DesignAnalysis and Design


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AimsAims

Discussion into what is IT Systems Discussion into what is IT Systems Analysis and Design and why it is Analysis and Design and why it is importantimportant

Understand the basic principles of a Understand the basic principles of a development lifecycledevelopment lifecycle

Gain an understanding into the waterfall Gain an understanding into the waterfall model and RADmodel and RAD

Discuss development methodologiesDiscuss development methodologies


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Systems analysisSystems analysis

What is Systems analysis?What is Systems analysis?– It is the study of a business problem in order to recommend It is the study of a business problem in order to recommend

improvements and to specify the requirements for a solutionimprovements and to specify the requirements for a solution– It is a phase that is undertaken when a current system is studied It is a phase that is undertaken when a current system is studied

and alternative replacement systems are proposedand alternative replacement systems are proposed– It is a detailed analysis of the what is required from a system i.e. It is a detailed analysis of the what is required from a system i.e.

user needsuser needs– Overall it is a process that is undertaken which involves Overall it is a process that is undertaken which involves

research into the current system, researching into what is research into the current system, researching into what is required from a new system etc. required from a new system etc. The information is then used to generate a clear list of user The information is then used to generate a clear list of user requirements from which designs can be generated and requirements from which designs can be generated and implemented to develop a system that meets the user implemented to develop a system that meets the user requirements.requirements.


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Systems analysisSystems analysisLets do an example?Lets do an example?

Imagine you have a really old sports car, you now have Imagine you have a really old sports car, you now have decided you require a different more sensible car to decided you require a different more sensible car to

accommodate your family need.accommodate your family need.

In order to find out what car would be most beneficial to you In order to find out what car would be most beneficial to you the following questions could be asked:the following questions could be asked:

What do you like about your current car?What do you like about your current car?What would you like to change about your current car?What would you like to change about your current car?

What would you require from a new car?What would you require from a new car?


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Why bother with Systems analysis?Why bother with Systems analysis?– Because most IT systems failBecause most IT systems fail


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What are the reasons for so many IT What are the reasons for so many IT systems failing?systems failing?– The company run out of money to finance the The company run out of money to finance the

project (incomplete system)project (incomplete system)– Missed requirements (more requirements may Missed requirements (more requirements may

have generated during the project lifecycle)have generated during the project lifecycle)– By the time the system is ready it has become By the time the system is ready it has become

out-of-dateout-of-date– ChangeoverChangeover– TestingTesting


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Using the Internet try to find out what other Using the Internet try to find out what other IT systems have failed – 15 MinutesIT systems have failed – 15 Minutes

We will discuss your findings within the We will discuss your findings within the classclass


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How can systems analysis be structured?How can systems analysis be structured?– We can structure the analysis process by We can structure the analysis process by

using standardised models called using standardised models called “Development life cycles”“Development life cycles”


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Systems Development life cycle (SDLC)Systems Development life cycle (SDLC)– A framework that describes the activities A framework that describes the activities

performed at each stage of a software performed at each stage of a software development project.development project.


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Systems Development lifecycleSystems Development lifecycle

Examples of a SDLC are:Examples of a SDLC are:- Waterfall model- Waterfall model - RAD- RAD

Prototype

Design

Assess

Test


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There are many others, using the Internet try to There are many others, using the Internet try to identify one other. identify one other.

Try to find out the benefits of the lifecycle you Try to find out the benefits of the lifecycle you identified. – 15 minutes hints: Spiral, V-Model …identified. – 15 minutes hints: Spiral, V-Model …


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Waterfall ModelWaterfall ModelRequirementsRequirements – defines – defines needed information, function, needed information, function, behavior, performance and behavior, performance and interfaces.interfaces.

Design Design – data structures, – data structures, software architecture, interface software architecture, interface representations, algorithmic representations, algorithmic details.details.

Implementation Implementation – source – source code, database, user code, database, user documentation, testing.documentation, testing.


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Waterfall Model strengthsWaterfall Model strengths– Easy to understandEasy to understand, easy to use, easy to use– Provides structure Provides structure to inexperienced staffto inexperienced staff– Milestones are well understoodMilestones are well understood– Sets Sets requirements stabilityrequirements stability– Good for Good for management control management control (plan, staff, (plan, staff,

track)track)– Works well when Works well when quality is more important quality is more important

than cost or schedulethan cost or schedule


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Waterfall Model disadvantagesWaterfall Model disadvantages– All All requirements must be known requirements must be known upfrontupfront– Deliverables created for each phase are Deliverables created for each phase are

considered frozen – considered frozen – inhibits flexibilityinhibits flexibility– Can give a Can give a false impression of progressfalse impression of progress– Does not reflect problem-solving nature Does not reflect problem-solving nature of of

software development – iterations of phasessoftware development – iterations of phases– Integration is Integration is one big bang at the endone big bang at the end– Little opportunity for customer Little opportunity for customer to preview the to preview the

system (until it may be too late)system (until it may be too late)


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When should the waterfall model be used?When should the waterfall model be used?– Requirements are very Requirements are very well knownwell known– Product definition is Product definition is stablestable– Technology is Technology is understoodunderstood– New New version of an existing productversion of an existing product


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Rapid applications development (RAD) Rapid applications development (RAD) modelmodel

Prototype

Design

Assess

Test

RAD is a software development methodology that focuses on building application fast – it involves iterative development.

It uses specialist tools like CASE tools that focus on converting requirements to code very quickly.

It makes use of prototypes that are iteratively developed (requirements can be refined/defined) into a fall system.


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RAD StrengthsRAD Strengths– Reduced cycle time Reduced cycle time and improved productivity and improved productivity

with fewer people means lower costswith fewer people means lower costs– Time-box Time-box approach mitigates cost and approach mitigates cost and

schedule riskschedule risk– Customer involved throughout Customer involved throughout the complete the complete

cycle minimizes risk of not achieving customer cycle minimizes risk of not achieving customer satisfaction and business needssatisfaction and business needs


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RAD disadvantagesRAD disadvantages– Accelerated development processAccelerated development process must give must give

quick responses quick responses to the userto the user– Risk of Risk of never achieving closure never achieving closure – Hard to use with Hard to use with legacy systemslegacy systems– Requires a system that can be Requires a system that can be modularizedmodularized– Developers and customers must be Developers and customers must be

committed to rapid-fire activities committed to rapid-fire activities in an in an abbreviated time frame. abbreviated time frame.


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The important thing to remember!The important thing to remember!

The key to a successful IT system is The key to a successful IT system is getting the requirements specification rightgetting the requirements specification right


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TaskTask

Complete Task 2, Bullet point one – One hourComplete Task 2, Bullet point one – One hour


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Development MethodologiesDevelopment MethodologiesA development methodology is the way in A development methodology is the way in which the development of a project is which the development of a project is carried-out.carried-out.A methodology helps to produce a better A methodology helps to produce a better quality productquality productHelps ensure that the user requirements Helps ensure that the user requirements are metare metAids project managementAids project managementAids communicationAids communication


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Development MethodologiesDevelopment Methodologies

– There are no guarantees that the lifecycle that There are no guarantees that the lifecycle that is chosen will structure an effective is chosen will structure an effective developmentdevelopment

– Every methodology has the same basic Every methodology has the same basic characteristicscharacteristics

– Each methodology make use of different tools Each methodology make use of different tools throughout each stage of the development i.e. throughout each stage of the development i.e. design tools, project management tools etcdesign tools, project management tools etc


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– There are different methodologies that can be There are different methodologies that can be used to provide some structure to a project. used to provide some structure to a project. Examples are shown below:Examples are shown below:

– SSADM (discussed in the next lecture)SSADM (discussed in the next lecture)– Object oriented methodologyObject oriented methodology


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Object oriented methodologyObject oriented methodology– Uses UML for notation – unified modelling Uses UML for notation – unified modelling

languagelanguage– The whole system is broken into a number of The whole system is broken into a number of

objects that are designed to interact with each objects that are designed to interact with each other to produce a working system.other to produce a working system.

– Used to build applications fastUsed to build applications fast– Used within an iterative environment (like Used within an iterative environment (like

RAD)RAD)


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Benefits of effective systems Benefits of effective systems analysis proceduresanalysis procedures

– Reduce risk of projects running over budget Reduce risk of projects running over budget or over timeor over time

– Good quality systems that are more likely to Good quality systems that are more likely to meet requirementsmeet requirements

– Manageable projectsManageable projects– Maintainable systemsMaintainable systems– Flexible systemsFlexible systems


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ConclusionConclusion

We Discussed what is IT Systems We Discussed what is IT Systems Analysis and Design and why it is Analysis and Design and why it is importantimportant

Acquired a basic knowledge of the Acquired a basic knowledge of the principles of a development lifecycleprinciples of a development lifecycle

Gained an understanding into the waterfall Gained an understanding into the waterfall model and RADmodel and RAD

Discussed development methodologiesDiscussed development methodologies

Documents

Btec National - IT SYSTEMS ANALYSIS AND DESIGN 1 IT Systems Analysis & Design Introduction into IT Systems Analysis and Design