Bài giảng Systems Analysis and Design - Chapter 17: Successfully Implementing the Information System

Summary Implementation Distributed systems Client/server Training users and personnel Conversion Direct changeover Parallel Phased Gradual Modular prototype

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Successfully Implementing the Information SystemSystems Analysis and Design, 7eKendall & Kendall17© 2008 Pearson Prentice HallLearning ObjectivesComprehend the implementation of a variety of distributed systemsDesign appropriate training programs for users of the new systemRecognize the differences among physical conversion strategies and be able to recommend an appropriate one to a clientAddress security, disaster preparedness, and disaster recoveryUnderstand the importance of evaluating the new system, and be able to recommend a suitable evaluation technique to a client2ImplementationThe process of ensuring that the information system is operational and then allowing users to take over its operation for use and evaluationImplementation considerations:Distributing processingTraining usersConverting from the old systemEvaluating the new system3Major TopicsClient/server computingNetwork typesGroupwareTrainingSecurityOrganizational metaphorsEvaluation4Implementing Distributed SystemsCan be conceived of as an application of telecommunicationsIncludes work stations that can communicate with each other and with data processorsMay have different hierarchical architectural configurations of data processors that communicate with each other5Client/Server TechnologyThe client/server (C/S) model refers to a design model that can be thought of as applications running on a local area network (LAN)The client is a networked computer that uses small programs to do front-end processing, including communicating with the userA file server stores the application programs and data for all the clients on the networkA print server is a PC dedicated to receiving and storing files to be printed6Advantages and Disadvantages of C/S ModelAdvantage - greater computer power and greater opportunity to customize applicationsDisadvantage - more expensive and applications must be written as two separate software components each running on separate machines7Figure 17.1 A client/server system configuration8Network TypesWide area network (WAN)Local area network (LAN)9Wireless Local Area Network (WLAN)Called Wi-Fi or 802.11, wireless fidelityCan include encryption wired equivalent privacy (WEP) for security purposesComparatively cheap to set upServe as a flexible technology for supporting work groups10Wireless Local Area Network (WLAN) (Continued)ConcernsSecuritySignal integrityWEP has many flaws, but used in conjunction with traditional LAN security measures is thought to be adequate for many home and business purposes11WiMaxWorldwide Interoperability for Microwave AccessAlso know as “Mobile WiMax”Greater wireless access range (30 miles)12BluetoothSuitable for personal networks and can include computers, printers, handheld devices, phones, keyboards, mice and household appliances13Types of Distributed Systems NetworksHierarchical Star Ring Bus 14HierarchicalThe host controls all other nodesComputers on the same level do not communicate with each other15StarThe central node communicates with the lesser nodesThe lesser nodes cannot directly communicate with each other16RingThere is no central computerAll the nodes are of equal computing powerEach node communicates directly with its neighbor17BusWork well in close quartersA single central cable is used to connect all the devices The single central cable serves as the only communication path18Network ModelingDraw a network decomposition diagram to provide an overview of the system Draw a hub connectivity diagram Explode the hub connectivity diagram to show the various workstations and how they are connected19Figure 17.2 Use special symbols when drawing network decomposition and hub connectivity diagrams20Figure 17.3 A network decomposition diagram for World’s Trend21Figure 17.4 A hub connectivity diagram for World’s Trend22Figure 17.5 A workstation connectivity diagram for World’s Trend23GroupwareSoftware that supports people working together in an organizationCan help group members to schedule and attend meetings, share data, create and analyze documents, communicate in unstructured ways, hold group conferences, do image management, manage and monitor workflow24Figure 17.8 There are five main advantages to creating distributed systems25Figure 17.9 There are four chief disadvantages to creating distributed systems26TrainingWho to trainPeople who train usersTraining objectivesTraining methods Training sitesTraining materials27Who to TrainAll people who will have primary or secondary use of the systemEnsure that users of different skill levels and job interests are separated28People Who Train UsersVendorsSystems analystsExternal paid trainersIn-house trainersOther system users29Figure 17.10 Appropriate training objectives, methods, sites, and materials are contingent on many factors 30Conversion StrategiesDirect changeoverParallel conversionGradual or Phased conversionModular prototype conversionDistributed conversion31Figure 17.11 Five conversion strategies for information systems32Direct ChangeoverAdvantageUsers have no possibility of using the old system rather than the new oneDisadvantageLong delays might ensue if errors occurUsers resent being forced into using an unfamiliar system without recourseNo adequate way to compare new results to old33Parallel ConversionAdvantageCan check new data against old dataFeeling of security to usersDisadvantageCost of running two systemsDoubling employees’ workloadsFaced with a choice, employees may pick old system34Gradual ConversionAdvantageAllows users to get involved with the system graduallyDisadvantageTaking too long to get the new system in placeInappropriateness for conversion of small, uncomplicated systems35Modular Prototype ConversionAdvantageEach module is thoroughly tested before being usedUsers are familiar with each module as it becomes operationalDisadvantagePrototyping is often not feasibleSpecial attention must be paid to interfaces36Distributed ConversionAdvantageProblems can be detected and containedDisadvantageEven when one conversion is successful, each site will have its own peculiarities to work through37Security ConcernsPhysical securityLogical securityBehavioral security38Security Concerns (Continued)Physical security is securing the computer facility, its equipment, and software through physical meansLogical security refers to logical controls in the software itselfBehavioral security is building and enforcing procedures to prevent the misusing of computer hardware and software39Special Security Considerations for EcommerceVirus protection softwareEmail filtering productsURL filtering productsFirewalls, gateways, and virtual private networksIntrusion detection products40Special Security Considerations for Ecommerce (Continued)Vulnerability management productsSecurity technologies such as secure socket layering (SSL) for authenticationEncryption technologiesPublic key infrastructure (PKI) use and obtaining a digital certificate41Privacy Considerations for EcommerceStart with a corporate policy on privacyOnly ask for information required to complete the transactionMake it optional for customers to fill out personal information on the Web site42Privacy Considerations for Ecommerce (Continued)Use sources that allow you to obtain anonymous information about classes of customersBe ethical43Disaster Recovery PlanningIdentify teams responsible for managing a crisisEliminate single points of failureDetermine data replication technologies that match the organization’s timetableCreate detailed relocation and transportation plans44Disaster Recovery Planning (Continued)Provide recovery solutions that include an off-site locationEnsure the physical and psychological well-being of employees and others45Identify Who Is ResponsibleWhether business operations will continueHow to support communicationsWhere people will be sent if the business is uninhabitableWhere personnel will go in an emergencySeeing to the personal and psychological needsRestoring the main computing and working environments46Single Points of Failure and Data Replication TechnologiesRedundancy of data provides the key for servers running Web applicationsSNAs and data mirroring47Relocation and Transportation PlansSend employees homeRemain on siteRelocate to a recovery facility48Communication ChannelsEmailEmergency information Web pageEmergency hotlineEmergency response agencies49Recovery Solutions and Support for the Well-Being of EmployeesRecovery involves an off-site location and converting paper documents to digital formatsWell-being of employees might include providing water or safety kits50Other Conversion ConsiderationsOrdering equipmentOrdering any external materials supplied to the information systemAppointing a manager to supervise the preparation of the installation sitePlanning, scheduling, and supervising programmers and data entry personnel51Figure 17.12 Organizational metaphors may contribute to the success or failure of an information system52Evaluation TechniquesCost-benefit analysisRevised decision evaluation approachUser involvement evaluationsThe information system utility approach53Information System Utility ApproachPossessionFormPlaceTimeActualizationGoal54Information System Utility Approach (Continued)Possession utility answers the question of who should receive outputGoal utility answers the why of information systems by asking whether the output has value in helping the organization achieve its objectivesPlace utility answers the question of where information is distributed55Information System Utility Approach (Continued)Form utility answers the question of what kind of output is distributed to the decision makerTime utility answers the question of when information is deliveredActualization utility involves how the information is introduced and used by the decision maker56Web Site EvaluationKnow how often the Web site is visitedLearn details about specific pages on the siteFind out more about the Web site’s visitors57Web Site Evaluation (Continued)Discover if visitors can properly fill out the forms you designedFind out who is referring Web site visitors to the client’s siteDetermine what browsers visitors are usingFind out if the client’s Web site visitors are interested in advertising58SummaryImplementationDistributed systemsClient/serverTraining users and personnelConversionDirect changeoverParallelPhasedGradualModular prototype59Summary (Continued)SecurityPhysicalLogicalBehavioralOrganizational metaphorsEvaluation60

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