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9
Moving to Design
Lecture 4
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9Analysis Objectives to Design ObjectivesFigure 9-2
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9Understanding the Elements of
Design
Design is the process of describing, organizing, and structuring the components of a system at both the architectural level and at a detailed level Focused on construction Like developing blueprints
Three questions What components require systems design? What are the inputs to and outputs of the
design process? How is systems design done?
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9Inputs and Outputs: Moving from
Analysis to Design
Design: Converts functional models from
analysis into models that represent the solution
Focused on technical issues Requires less user involvement than
analysis
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9SDLC Phases with Design Phase ActivitiesFigure 9-4
Design and Integrate NetworkDesign the Application ArchitectureDesign the User InterfacesDesign the System InterfacesDesign and Integrate the DatabasePrototype for Design DetailsDesign and Integrate System Controls
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9Structured Approach to Designing
the Application Architecture
Application software programs Designed in conjunction with database and user
interfaces Hierarchy of modules
Documented with system flowcharts
Design internal program logic
Top-down approach DFDs with automation boundaries Structure charts
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9Structured Design Models
Figure 9-7
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9
Automation System Boundary
Partitions data flow processes into manual and automated systems
Processes can be inside or outside boundary
Data flows can be inside and outside of boundary
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9DFD with Automation System BoundaryFigure 9-8
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9
System Flowchart
Representation of various computer programs, files, databases, and associated manual processes
Graphically describes organization of subsystems
Can show type of system Batch Real time
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9Common System Flow Chart SymbolsFigure 9-9
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9System Flow Chart for RMO
Figure 9-11
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9
Structure Chart
Describes functions and subfunctions of each part of system
Shows relationships between modules of a computer program
Simple and direct method Each module performs a specific function Each layer in a program performs specific
activities
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9Structure Chart for Entire Payroll Program
Figure 9-14
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9The Create New Order DFD FragmentFigure 9-17
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9Exploded View of Create New Order DFDFigure 9-18
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9Rearranged Create New Order DFDFigure 9-19
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9First Draft of the Structure Chart
Figure 9-20