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Program Design.Systems analysis and design, 6th.edition.Dennis, wixom, and roth.Roberta M. Roth © 2015 John Wiley & Sons, Inc. All rights 1Learning ObjectivesBe able to revise logical DFDs into physical DFDsBe able to create a structure chartBe able to write a program specificationBe able to write instructions using pseudocodeBecome familiar with event-driven programming © 2015 John Wiley & Sons, Inc. All rights 2Moving from Logical to Physical.Process ModelsMaking implementation decisions. © 2015 John Wiley & Sons, Inc. All rights 3The Physical Process ModelShow the implementation details and explain how the system will work, including.◦ Actual, specific technology.◦ Format of information.◦ Human interaction with system. © 2015 John Wiley & Sons, Inc. All rights 4The Physical DFDContains the same components as the logical DFD.The same rules pertaining to balance and.decomposition apply.Contains additional details describing how the system.will be built. © 2015 John Wiley & Sons, Inc. All rights 5Steps to Create the Physical DFDAdd implementation references.Draw a human-machine boundary.Add system-related data stores, data flows and.processes.Update data elements in the data flows.Update the metadata in the CASE repository © 2015 John Wiley & Sons, Inc. All rights 6Contrasting a Logical and Physical.DFD.Logical DFD Physical dfd. © 2015 John Wiley & Sons, Inc. All rights 7Designing Programs. © 2015 John Wiley & Sons, Inc. All rights 8Key DefinitionsProgram design - creating instructions for the programmers.The top-down, modular approach - begin with the “big picture” and gradually add detail.Program design document – all structure charts and specifications needed by.programmers to implement the systemThe Structure ChartImportant program design technique.Shows all components of code in a hierarchical format. ◦ Sequence. ◦ Selection. ◦ Iteration.Illustrates the organization and interactions of the different program modules. © 2015 John Wiley & Sons, Inc. All rights 10Example.Structure.Chart. © 2015 John Wiley & Sons, Inc. All rights 11Structure Chart Elements Module Conditional Line. P. e. g. a. O. f. f. 1.2. Calculate. Current GPA. Library Module. On. Control Couple page. 1.1. Get Student. Grade Record. Data Couple. Loop. © 2015 John Wiley & Sons, Inc. All rights 12Building the Structure ChartProcesses in the DFD tend to represent one module.on the structure chart.◦ Afferent processes – provide inputs to system.◦ Central processes – perform critical system operations.◦ Efferent processes – handle system outputsThe DFD leveling can correspond to the structure.chart hierarchy © 2015 John Wiley & Sons, Inc. All rights 13Types of Structure ChartsTransaction structure – control module calls subordinate modules, each of which.handles a particular transaction.◦ Few afferent processes.◦ Many efferent processes.◦ Higher up levels of structure chart.◦ Concerned with coordinating the production of outputs. © 2015 John Wiley & Sons, Inc. All rights 14Transactio.n Structure