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Transcript of Btec National - IT SYSTEMS ANALYSIS AND DESIGN 1 IT Systems Analysis & Design Introduction into IT...
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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Systems analysisSystems analysis
Why bother with Systems analysis?Why bother with Systems analysis?– Because most IT systems failBecause most IT systems fail
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Systems analysisSystems analysis
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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Systems analysisSystems analysis
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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Systems analysisSystems analysis
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 analysisSystems analysis
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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Systems Development lifecycleSystems Development lifecycle
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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Systems Development lifecycleSystems Development lifecycle
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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Systems Development lifecycleSystems Development lifecycle
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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Systems Development lifecycleSystems Development lifecycle
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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Systems Development lifecycleSystems Development lifecycle
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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Systems Development lifecycleSystems Development lifecycle
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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Systems Development lifecycleSystems Development lifecycle
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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Systems Development lifecycleSystems Development lifecycle
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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Development MethodologiesDevelopment Methodologies
– 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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Development MethodologiesDevelopment Methodologies
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