03/11/20151 System Development Lifecycle Design

203/11/2015 Learning 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.

303/11/2015 Identification Feasibility study Information Collection Analysis DesignDevelopment and Testing Implementation Maintenance Obsolescence

03/11/20154 Design Phase If the new system is deemed feasible then …

503/11/2015 Relevance of data Which data has a bearing, or use?

603/11/2015 Timeliness of data When does the data become outdated? Data changes over time and is only part of a sensible solution for a short period. Data changes over time and is only part of a sensible solution for a short period.

703/11/2015 Decisions to be made about the data in a new system Data to be input and data to be output Relative importance of different types of data Types of data Amount / type of data storage required Data structures to be used Is data to be static or regularly altered? Access methods Access methods

803/11/2015 Inputs, Processing and Outputs What inputs are needed? What processing must take place? What information needs to be output? Can be explained in: Can be explained in:WordsTablesFlowcharts Systems flowcharts Data flow diagrams Algorithms Structure diagrams

903/11/2015 Jackson diagrams

1003/11/2015 Jackson diagrams Shows how the solution can be split into modules using the top down approach. Show the links between modules.

1103/11/2015 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 who are present and absent.. System needs to print out the number of students who are present and absent..

1203/11/2015 Data flow diagrams / System flow charts

1303/11/2015 Data flow diagrams / System flow charts Boxes are used to stand for input, processes, storage, and output which show the storage locations of different data. Arrows show the way that data enters and leaves the system and how the data relates to each other during processing.

Gantt Charts When a major project is undertaken, there will be a number of different tasks to be carried out. Some tasks may be able to be done at the same time. It may also be important to work out how long the project should take to complete. Major projects like this can be represented graphically to show the different tasks and how they join together, or relate to each other.

E.g. Building a bungalow AConcreting the foundationstakes 4 days BBuilding the wallstakes 4 days CMaking the doors and windowstakes 7 days DTiling the rooftakes 2 days EInstalling the plumbingtakes 3 days FDoing the interior carpentrytakes 4 days GInstalling the electricstakes 6 days HDecoratingtakes 5 days

Example Gantt Chart

Spider diagrams Shows the interaction (rather than just showing the stages like Gantt charts do) between the different stages and those stages which are independent of each other. 1703/11/ mind.com/spider-diagrams.html

1803/11/2015 Output Formats When data has been processed by a computer system it is necessary to report the results of the processing.

1903/11/2015 Graphs Advantages: Show trends very clearly. Show trends very clearly. Different types of graph can illustrate different characteristics. Different types of graph can illustrate different characteristics. A visual representation can be very useful. A visual representation can be very useful.Disadvantages: A very misleading picture can be given if the scales are wrong. A very misleading picture can be given if the scales are wrong. Specific values are not easily read from a graph. Specific values are not easily read from a graph.

2003/11/2015 Reports in text form Advantages: Produce actual figures. Produce actual figures.Disadvantage: May need skill to interpret the significance of the figures. May need skill to interpret the significance of the figures. Figures not arranged in a form that makes interpretation easy. Figures not arranged in a form that makes interpretation easy.

2103/11/2015 Reports in tabular form Advantages: Provide exact figures which can be compared with adjacent readings Provide exact figures which can be compared with adjacent readingsDisadvantage: May need skill to interpret the significance of the figures. May need skill to interpret the significance of the figures.

2203/11/2015 Interactive presentations E.g. Like this one. Like this one. The user decides the type and range of output required to suit their needs so there is some positive user involvement.

2303/11/2015 Sound Alarms if some condition is breached. Can inform while an operator is doing something else. Can inform while an operator is doing something else. Elicits an immediate response. Elicits an immediate response.

2403/11/2015 Lights To indicate state of a process and / or alert an operator.

2503/11/2015 Analogue / digital meters To provide readings.

2603/11/2015 Video Advantage: Useful for demonstration of techniques where there is little value in pages of instruction if a simple video can illustrate it better. Useful for demonstration of techniques where there is little value in pages of instruction if a simple video can illustrate it better.Disadvantage: Large amounts of memory. Large amounts of memory.

2703/11/2015 Hardcopy V On Screen Most of the previous output formats can be presented on screen or as hardcopy (paper). On screen Provides quick visual representation of a process to identify where problems are. Provides quick visual representation of a process to identify where problems are. Hard copy text Provide evidence for later study. Provide evidence for later study. Portability away from a computer so can be taken from a terminal and used at the point of need. Portability away from a computer so can be taken from a terminal and used at the point of need.

2803/11/2015 Speed mismatch The name given to the difference in reaction time of a operator and the computer. The computer is able to take decisions very quickly, while the operator works very slowly. The computer is able to take decisions very quickly, while the operator works very slowly. If necessary a computer override must be built into a system meaning the computer does not wait for the operator to react but takes control and reports its actions to the operator. If necessary a computer override must be built into a system meaning the computer does not wait for the operator to react but takes control and reports its actions to the operator.

2903/11/2015 Plenary Describe data flow and Jackson Structure diagrams? - Data flow diagrams / system flow charts… - Data flow diagrams / system flow charts… show the way that data enters and leaves the system and… the storage locations of different data… and how the data relates to each other during processing… - Jackson Structure Diagram - Jackson Structure Diagram shows how the solution can be split into modules… using the top down approach… and showing the links between modules.

3003/11/2015 Plenary What decisions will need to be made by an analyst about the data in a new system? Types of data Types of data Amount / type of data storage required Amount / type of data storage required Data structures to be used Data structures to be used Is data to be static or regularly altered? Is data to be static or regularly altered? Access methods

3103/11/2015 Plenary Describe the possible output formats of a system? Graphs Graphs Ideal for showing trends. Reports in text form Reports in text form Gives exact details / figures. Reports in tabular form Reports in tabular form Arranges exact details to make them simpler to interpret. Interactive presentation on screen Interactive presentation on screen Allows the manager to tailor the output required. Sound / Lights Sound / Lights Can inform while the manager is doing something else.

3203/11/2015 Plenary Explain what is meant by the timeliness and relevance of data. Timeliness is the concept that data changes over time and that data is only part of a sensible solution for a short period before it becomes outdated. Timeliness is the concept that data changes over time and that data is only part of a sensible solution for a short period before it becomes outdated. Relevance of data means that data has a bearing, or use, in that particular application. Relevance of data means that data has a bearing, or use, in that particular application.

3303/11/2015 Plenary Explain speed mismatch and how it is coped with in critical situations? The name given to the difference in reaction time of the operator and the computer. The name given to the difference in reaction time of the operator and the computer. A computer override must be built into a system meaning the computer does not wait for the operator to react but takes control and reports its actions to the operator. A computer override must be built into a system meaning the computer does not wait for the operator to react but takes control and reports its actions to the operator.