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(共14张PPT)
Chapter 22Systems Design, Implementation, and Operation22-Learning ObjectivesDiscuss the conceptual systems design process and the activities in this phase.Discuss the physical systems design process and the activities in this phase.Discuss the systems implementation and conversion process and the activities in this phase.Discuss the systems operation and maintenance process and the activities in this phase.22-Systems Development Life Cycle (SDLC)22-Conceptual DesignDeveloper creates a general framework for implementing user requirements and solving the problems identified in the analysis phase.Evaluating design alternativesPreparing design specificationsPreparing the conceptual systems design report22-Preparing Design SpecificationsOutputHow often What should reports contain What should reports look like Should reports be online or hard copy or both Data StorageWhat data elements must be stored to produce a report How they should be stored What type of file or database should be used InputWhere, when, and how to collect the data Processing Procedures and Operations22-Physical DesignConceptual designs are translated into detailed specifications that are used to code and test the computer programs.OutputFile and databaseInputProgramProceduresControls22-Output DesignDetermine the nature, format, content, and timing of reports, documents, and screen displays.Types of Output:Scheduled reportsSpecial-purpose analysis reportsTriggered exception reportsDemand reports22-Program DesignDetermine user needs.Create and document development plan.Write program instructions (code the system).Test the program (debug for errors).Document the program.Train the users.Install the system.Use and modify the system.22-Procedures and ControlsProcedures for who, what, where, why, when:Input preparationTransaction processingError detection and correctionControlsReconciliation of balancesDatabase accessOutput preparation and distributionComputer operator instructionsControl considerations:ValidityAuthorizationAccuracySecurityNumerical controlAvailabilityMaintainabilityIntegrityAudit control22-Implementation and ConversionProcess of installing hardware and software and getting the AIS up and runningPlanningPrepare siteTrain personnelComplete documentationTest systemConversion22-Types of DocumentationDevelopment DocumentationA system description; copies of output, input, and file and database layouts; program flowcharts; test results; and user acceptance formsOperations DocumentationIncludes operating schedules; files and databases accessed; and equipment, security, and file-retention requirementsUser DocumentationTeaches users how to operate the AIS; it includes a procedures manual and training materials22-Types of System TestingWalk-ThroughStep-by-step reviews of procedures or program logic to find incorrect logic, errors, omissions, or other problemsProcessing Test DataUsing both valid transactions and all possible error conditionsAcceptance TestsReal transactions and files rather than hypothetical ones, users develop the acceptance criteria and make the final decision whether to accept the AIS22-Types of ConversionsDirectTerminates the old AIS when the new one is introducedParallelOperates the old and new systems simultaneously for a periodPhase-inGradually replaces elements of the old AIS with the new onePilotImplements a system in one part of the organization, such as a branch locationLocalizes conversion problems and allows training in a live environment22-Operations and MaintenancePost-Implementation ReviewDetermines whether the system meets its planned objectives22-

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