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System Development System Development LifecycleLifecycle

DesignDesign

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Learning ObjectivesLearning Objectives

Consider the relevance and timeliness of data.Describe:

The processes of determining the type and amount of data to be stored.

The variety and scope of output formats from a system.

How to design the input, output and processing elements of the system using JSP and data flow diagrams (system flowcharts).

Consider animations, video, sound and presentations and their critical effect upon the overall impression on the audience.

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Identification

Feasibility study

Information Collection

Analysis

DesignDevelopment and Testing

Implementation

Maintenance

Obsolescence

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Design PhaseDesign Phase

If the new system is deemed If the new system is deemed feasible then …feasible then …

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Relevance of dataRelevance of data

Which data has a bearing, or use?Which data has a bearing, or use?

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Timeliness of dataTimeliness of data

When does the data become outdated?When does the data become outdated? Data changes over time and is only part of a Data changes over time and is only part of a

sensible solution for a short period.sensible solution for a short period.

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Decisions to be made about the Decisions to be made about the data in a new system data in a new system

Data to be input and data to be outputData to be input and data to be outputRelative importance of different types of Relative importance of different types of datadataTypes of dataTypes of dataAmount / type of data storage requiredAmount / type of data storage requiredData structures to be usedData structures to be usedIs data to be static or regularly altered?Is data to be static or regularly altered?

Access methodsAccess methods

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Inputs, Processing and OutputsInputs, Processing and Outputs

What inputs are needed?What inputs are needed?What processing must take place?What processing must take place?What information needs to be output?What information needs to be output? Can be explained in:Can be explained in:

Words Words TablesTablesFlowchartsFlowchartsSystems flowchartsSystems flowchartsData flow diagramsData flow diagramsAlgorithmsAlgorithmsStructure diagramsStructure diagrams

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Jackson diagramsJackson diagrams

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Jackson diagramsJackson diagrams

Shows how the solution can be split into Shows how the solution can be split into modules using the top down approach.modules using the top down approach.

Show the links between modules.Show the links between modules.

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E.g.E.g. A register is taken of the 25 students in a class. A register is taken of the 25 students in a class. System needs to print out the number of students System needs to print out the number of students

who are present and absentwho are present and absent....

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Data flow diagrams / System flow Data flow diagrams / System flow chartscharts

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Data flow diagrams / System flow Data flow diagrams / System flow chartscharts

Boxes are used to stand for input, Boxes are used to stand for input, processes, storage, and output which processes, storage, and output which show the storage locations of different show the storage locations of different data.data.

Arrows show the way that data enters and Arrows show the way that data enters and leaves the system and how the data leaves the system and how the data relates to each other during processingrelates to each other during processing..

Gantt ChartsGantt Charts

When a major project is undertaken, there will When a major project is undertaken, there will be a number of different tasks to be carried out. be a number of different tasks to be carried out.

Some tasks may be able to be done at the same Some tasks may be able to be done at the same time.time.

It may also be important to work out how long It may also be important to work out how long the project should take to complete.the project should take to complete.

Major projects like this can be represented Major projects like this can be represented graphically to show the different tasks and how graphically to show the different tasks and how they join together, or relate to each other.they join together, or relate to each other.

E.g. Building a bungalowE.g. Building a bungalowAA Concreting the foundationsConcreting the foundationstakes 4 daystakes 4 days

BB Building the wallsBuilding the walls takes 4 daystakes 4 days

CC Making the doors and windowsMaking the doors and windows takes 7 daystakes 7 days

DD Tiling the roofTiling the roof takes 2 daystakes 2 days

EE Installing the plumbingInstalling the plumbing takes 3 daystakes 3 days

FF Doing the interior carpentryDoing the interior carpentry takes 4 daystakes 4 days

GG Installing the electricsInstalling the electrics takes 6 daystakes 6 days

HH DecoratingDecorating takes 5 daystakes 5 days

Example Gantt ChartExample Gantt Chart

Spider diagramsSpider diagrams

Shows the Shows the interactioninteraction (rather than just (rather than just

showing the stages like Gantt charts do)showing the stages like Gantt charts do) between the between the different stages and those stages which different stages and those stages which are independent of each other.are independent of each other.

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http://www.the-organic-mind.com/spider-diagrams.html

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Output FormatsOutput Formats

When data has been processed by a When data has been processed by a computer system it is necessary to report computer system it is necessary to report the results of the processing. the results of the processing.

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GraphsGraphs

Advantages:Advantages: Show trends very clearly. Show trends very clearly. Different types of graph can illustrate different Different types of graph can illustrate different

characteristics.characteristics. A visual representation can be very useful. A visual representation can be very useful.

Disadvantages:Disadvantages: A very misleading picture can be given if the scales A very misleading picture can be given if the scales

are wrong.are wrong. Specific values are not easily read from a graph.Specific values are not easily read from a graph.

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Reports in text form Reports in text form

Advantages:Advantages: Produce actual figures. Produce actual figures.

Disadvantage:Disadvantage: May need skill to interpret the significance of May need skill to interpret the significance of

the figures.the figures. Figures not arranged in a form that makes Figures not arranged in a form that makes

interpretation easy.interpretation easy.

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Reports in tabular form Reports in tabular form

Advantages:Advantages: Provide exact figures which can be compared Provide exact figures which can be compared

with adjacent readings with adjacent readings

Disadvantage:Disadvantage: May need skill to interpret the significance of May need skill to interpret the significance of

the figures.the figures.

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Interactive presentationsInteractive presentations

E.g.E.g. Like this one.Like this one.

The user decides the type and range of The user decides the type and range of output required to suit their needs so there output required to suit their needs so there is some positive user involvement.is some positive user involvement.

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SoundSound

Alarms if some condition is breached.Alarms if some condition is breached. Can inform while an operator is doing Can inform while an operator is doing

something else.something else. Elicits an immediate response.Elicits an immediate response.

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LightsLights

To indicate state of a To indicate state of a process and / or alert process and / or alert an operator.an operator.

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Analogue / digital metersAnalogue / digital meters

To provide readings.To provide readings.

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VideoVideo

Advantage:Advantage: Useful for demonstration of techniques where Useful for demonstration of techniques where

there is little value in pages of instruction if a there is little value in pages of instruction if a simple video can illustrate it better.simple video can illustrate it better.

Disadvantage:Disadvantage: Large amounts of memory.Large amounts of memory.

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Hardcopy Hardcopy VV On Screen On Screen

Most of the previous output formats can be Most of the previous output formats can be presented on screen or as hardcopy (paper).presented on screen or as hardcopy (paper).

On screenOn screen Provides quick visual representation of a process to Provides quick visual representation of a process to

identify where problems are.identify where problems are.

Hard copy textHard copy text Provide evidence for later study.Provide evidence for later study. Portability away from a computer so can be taken Portability away from a computer so can be taken

from a terminal and used at the point of need. from a terminal and used at the point of need.

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Speed mismatchSpeed mismatch

The name given to the difference in reaction The name given to the difference in reaction time of a operator and the computer.time of a operator and the computer.

The computer is able to take decisions very quickly, The computer is able to take decisions very quickly, while the operator works very slowly.while the operator works very slowly.

If necessary a computer override must be built into If necessary a computer override must be built into a system meaning the computer does not wait for a system meaning the computer does not wait for the operator to react but takes control and reports the operator to react but takes control and reports its actions to the operator.its actions to the operator.

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PlenaryPlenary

Describe data flow and Jackson Structure Describe data flow and Jackson Structure diagrams?diagrams?

- Data flow diagrams / system flow charts…- Data flow diagrams / system flow charts…show the way that data enters and leaves the system show the way that data enters and leaves the system and…and…

the storage locations of different data…the storage locations of different data…

and how the data relates to each other during and how the data relates to each other during processing…processing…

- Jackson Structure Diagram- Jackson Structure Diagramshows how the solution can be split into modules…shows how the solution can be split into modules…

using the top down approach…using the top down approach…

and showing the links between modules.and showing the links between modules.

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PlenaryPlenary

What decisions will need to be made by an What decisions will need to be made by an analyst about the data in a new system?analyst about the data in a new system? Types of dataTypes of data Amount / type of data storage requiredAmount / type of data storage required Data structures to be usedData structures to be used Is data to be static or regularly altered?Is data to be static or regularly altered?

Access methodsAccess methods

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PlenaryPlenary

Describe the possible output formats of a Describe the possible output formats of a system?system? GraphsGraphs

Ideal for showing trends.Ideal for showing trends. Reports in text formReports in text form

Gives exact details / figures.Gives exact details / figures. Reports in tabular formReports in tabular form

Arranges exact details to make them simpler to interpret.Arranges exact details to make them simpler to interpret. Interactive presentation on screenInteractive presentation on screen

Allows the manager to tailor the output required.Allows the manager to tailor the output required. Sound / LightsSound / Lights

Can inform while the manager is doing something else.Can inform while the manager is doing something else.

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PlenaryPlenary

Explain what is meant by the timeliness Explain what is meant by the timeliness and relevance of data. and relevance of data.

Timeliness is the concept that data changes Timeliness is the concept that data changes over time and that data is only part of a over time and that data is only part of a sensible solution for a short period before it sensible solution for a short period before it becomes outdated.becomes outdated.

Relevance of data means that data has a Relevance of data means that data has a bearing, or use, in that particular application.bearing, or use, in that particular application.

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PlenaryPlenary

Explain speed mismatch and how it is Explain speed mismatch and how it is coped with in critical situations?coped with in critical situations?

The name given to the difference in reaction The name given to the difference in reaction time of the operator and the computer. time of the operator and the computer.

A computer override must be built into a A computer override must be built into a system meaning the computer does not wait system meaning the computer does not wait for the operator to react but takes control for the operator to react but takes control and reports its actions to the operator.and reports its actions to the operator.