體系結構和流程設計的應用

陳士昂整理日期：05年10月17日知識素材：體系結構和流程設計的應用2023/1/24AMT－企業(yè)資源管理研究中心?本資料在企業(yè)資源管理研究中心（AMT）文檔控制范圍之內，在得到許可后方可使用資料來源：〔ApplicationArchitecture&ProcessDesign〕

日程第一部分何謂信息系統的體系結構第二部分集中式和分布式的體系結構第三部分信息系統設計中的數據庫設計第四部分用戶和數據系統界面問題第五部分大標題5第六部分大標題6IntroductionThechapterwilladdressthefollowingquestions:Whatisaninformationsystem’sarchitectureintermsofDATA,PROCESSES,INTERFACES,andNETWORKS—thebuildingblocksofallinformationsystems?Whatarebothcentralizedanddistributedcomputingalternativesforinformationsystemdesign,includingvariousclient/serverandInternet/intranetoptions?Whatarethedatabaseanddatadistributionalternativesforinformationsystemdesign?Whatarethemakeversusbuyalternativesandvariationsforinformationsystemdesign?Whataretheuserandsysteminterfacealternativesforinformationsystemdesign?IntroductionThechapterwilladdressthefollowingquestions:Whatarethevariousnetworkingtopologiesandtheirimportanceininformationsystemdesign?Whatarethemethodsforgeneralapplicationarchitectureanddesign?Whatarethedifferencesbetweenlogicalandphysicaldataflowdiagrams,andexplainhowphysicaldataflowdiagramsareusedtomodelapplicationarchitectureandguideprocessdesign?Howdoyoudrawphysicaldataflowdiagramsforasystem/application?GeneralSystemDesignDuringgeneralsystemsdesignthebasictechnicaldecisionsaremade.Thesedecisionsinclude:Willthesystemusecentralizedordistributed?Willthesystem’sdatastoresbecentralizedordistributed?Ifdistributed,howso?Whatdatastoragetechnology(s)willbeused?Willsoftwarebepurchased,builtin-house,orboth?Forprogramstobewritten,whattechnology(s)willbeused?Howwillusersinterfacewiththesystem?Howwilldatabeinput?Howwilloutputsbegenerated?Howwillthesysteminterfacetoother,existingsystems?GeneralSystemDesignThedecisionsmadeduringgeneralsystemsdesignconstitutetheapplicationarchitectureofthesystem.Anapplicationarchitecturedefinesthetechnologiestobeusedby(andtobuild)one,more,orallinformationsystemsintermsofitsdata,process,interface,andnetworkcomponents.Itservesasaframeworkforgeneraldesign.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingWhatisclient/servercomputing?Aclientissingle-usercomputerthatprovides(1)userinterfaceservices,appropriatedatabaseandprocessingservices;and(2)connectivityservicestoservers(andpossiblyotherclients).Aserverisamultiple-usercomputerthatprovides(1)shareddatabase,processing,andinterfaceservices;and(2)connectivitytoclientsandotherservers.Inclient/servercomputinganinformationsystem’sdatabase,software,andinterfacesaredistributedacrossanetworkofclientsandserverswhichcommunicateandcooperatetoachievesystemobjectives.Despitethedistributionofcomputingresources,eachsystemuserperceivesthatasinglecomputer(theirownclientPC)isdoingallthework.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingClient/servercomputingisanalternativetotraditionalcentralizedcomputing.Incentralizedcomputing,amulti-usercomputer(usuallyamainframeorminicomputer)hostsalloftheinformationsystemcomponentsincluding(1)thedatastorage(filesanddatabases),(2)thebusinesslogic(softwareandprograms),(3)theuserinterfaces(inputandoutput),and(4(anysysteminterfaces(networkingtoothercomputersandsystems).Theusermayinteractwiththishostcomputerviaaterminal(or,today,aPCemulatingaterminal),butallofworkisactuallydoneonthehostcomputer.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingCentralizedComputing:Centralizedprocessarchitectureswereoncedominantbecausethecostofplacingcomputersclosertotheend-userwasprohibitive.Many(ifnotmost)legacyapplicationsremaincentralizedonlargemainframecomputers(suchasIBM’’sS/370and3090familiesofcomputers)orsmallerminicomputers(suchasIBM’’sAS/400).InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingDistributedPresentation:Thisalternativebuildsuponandenhancescentralizedcomputingapplications.TheoldcharacteruserinterfacesarestrippedfromthecentralizedapplicationsandregeneratedasgraphicaluserinterfacesthatwillrunonthePC.Theuserinterface(orpresentation)isdistributedofftheserverandontotheclient.Allotherelementsofthecentralizedapplicationremainontheserver,butthesystemusersgetafriendliergraphicaluserinterfacetothesystem.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingDistributedPresentation:Distributedpresentationcomputingadvantages:Itcanbeimplementedrelativelyquicklysincemostaspectsofthelegacyapplicationremainunchanged.UsersgetafriendlyandfamiliarinterfacetoexistingsystemsTheusefullifetimeoflegacyapplicationscanbeextendeduntilsuchatimeasresourceswarrantawholesaleredevelopmentoftheapplication.Distributedpresentationcomputingdisadvantages:Theapplication’’sfunctionalitycannotbesignificantlyimproved,andthesolutiondoesnotmaximizethepotentialoftheclient’sdesktopcomputerbyonlydealingwiththeuserinterface.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingDistributedData:Sometimescalledtwo-tieredclient/server.Thisarchitectureplacestheinformationsystem’sstoreddataonaserver,andthebusinesslogicanduserinterfacesontheclients.Alocalorwideareanetworkusuallyconnectstheclientstotheserver.Alocalareanetwork(orLAN)isasetofclientcomputers(usuallyPCs)connectedtooneormoreservercomputers(usuallymicroprocessor-based,butcouldalsoincludemainframesorminicomputers)throughcableoverrelativelyshortdistances.Awideareanetwork(orWAN)isaninterconnectedsetofLANs,ortheconnectionofPCsoveralongerdistance.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingDistributedData:Thedatabaseserverisfundamentaltothisarchitectureandit’’stechnologyisdifferentfromafileserver.Fileserversstorethedatabase,buttheclientcomputersmustexecutealldatabaseinstructions.Thismeansthatentiredatabasesandtablesmayhavetobetransportedtoandfromtheclientacrossthenetwork.Databaseserversalsostorethedatabase,butthedatabasecommandsarealsoexecutedonthoseservers.Theclientsmerelysendtheirdatabasecommandstotheserver.Theserveronlyreturnstheresultofthedatabasecommandprocessing——notentiredatabasesortables.Thus,databaseserversgeneratemuchlessnetworktraffic.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingDistributedData:Theclientsinthedistributeddatabasesolutiontypicallyrunthebusinesslogicoftheinformationsystemapplication.Distributeddatacomputingadvantages:Separatesdataandbusinesslogicto(1)isolateeachfromchangestotheother,(2)makethedatamoreavailabletousers,and(3)retainthedataintegrityofcentralizedcomputingthroughcentrallymanagedservers.Distributeddatacomputingdisadvantages:Theapplicationlogicmustbemaintainedonalloftheclients.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingDistributedDataandLogic:Referredtoasthree-tieredorn-tieredclient/servercomputing.Thisapproachdistributesdatabasesandbusinesslogictoseparateservers.Usesthesamedatabaseserver(s)asinthetwo-tieredapproach.Usesanapplicationserver.Theapplicationserverprovidesatransactionmonitorsuchastomanagetransactions.Someorallofthebusinesslogicoftheapplicationcanbemovedfromtheclienttotheapplicationserver.Onlytheuserinterfaceandsomerelativelystableorpersonalbusinesslogicneedbeexecutedontheclients.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingDistributedDataandLogic:Distributeddataandlogiccomputingdisadvantages:Verycomplextodesignanddevelopment.Themostdifficultaspectofthree-tierclient/serverapplicationdesignispartitioning.Partitioningistheactofdetermininghowtobestdistributeorduplicateapplicationcomponents(data,process,andinterfaces)acrossthenetwork.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingTheInternetandIntranets:TheInternetisan(butnotnecessarily‘the’)informationsuperhighwaythatpermitscomputersofalltypesandsizes,allovertheworldtoexchangedataandinformationusingstandardlanguagesandprotocols.Anintranetisasecurenetwork,usuallycorporate,thatusesInternettechnologytointegratedesktop,workgroup,andenterprisecomputingintoasinglecohesiveframework.TheintranetprovidesmanagementanduserswithacommoninterfacetoapplicationsandinformationInformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingTheInternetandIntranets:Javaisacross-platformprogramminglanguagedesignedspecificallytoexploittheInternetstandards.Javaapplets(modularsoftwarecomponents)arestoredonanInternetorintranetserveranddownloadedtotheclientwhentheyaccesstheapplication.Javaappletscanexecuteonanyclientcomputingplatform.Anetworkcomputer(orNC)isdesignedtoonlyrunInternet-basedapplications(suchaswebbrowsersandJavaapplets).TheNC(alsocalledathinclient)issimpler,andmuchcheaperthanpersonalcomputers(increasinglycalledafatclient).InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingTheRoleofNetworkTechnologies:Thewelldesignednetworkprovidesconnectivityandinteroperability.Connectivitydefineshowcomputersareconnectedto“talk”tooneanother.Interoperabilityisanidealstateinwhichconnectedcomputerscooperatewithoneanotherinamannerthatistransparenttotheirusers(theclients).Networktopologydescribeshowanetworkprovidesconnectivitybetweenthecomputersonthatnetwork.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingTheRoleofNetworkTechnologies:TheBusnetworktopology:Adirectpoint-to-pointlinkbetweenanytwocomputersystems.Thesimplestnetworktopology.Thenetworkcancontainmainframes,minicomputers(ormid-rangecomputers),personalcomputers,anddumbandintelligentterminals.Tocompletelyconnectallpointsbetweenncomputers,youwouldneedntimes(n-1)/2directpaths.Onlyonecomputercansenddatathroughthebusatanygiventime.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingTheRoleofNetworkTechnologies:TheRingnetworktopology:Connectsmultiplecomputersandsomeperipheralsintoaring-likestructure.Eachcomputercantransmitmessages,instructions,anddata(calledpackets)toonlyoneothercomputer(ornodeonthenetwork).Everytransmissionincludesanaddress.Whenacomputerreceivesapacket,itcheckstheaddressandifthepacket’saddressisdifferentthanthecomputer’’saddress,itpassesitontothenextcomputerornode.Ringnetworksgenerallytransmitpacketsinonedirection;therefore,manycomputerscantransmitatthesametimetoincreasenetworkthroughput.InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingTheRoleofNetworkTechnologies:TheStarnetworktopology:Linksmultiplecomputersystemsthroughacentralcomputer.Thecentralcomputerdoesnothavetobeamainframeorminicomputer.Centralcomputercouldbeanapplicationserverthatmanagesthetransmissionofdataandmessagesbetweentheotherclientsandservers(asinthen-tiermodel).InformationTechnologyArchitectureNetworkArchitecturesforClient/ServerComputingTheRoleofNetworkTechnologies:TheHierarchicalnetworktopology:Canbethoughtofasamultiplestarnetwork,wherethecommunicationsprocessorsarearrangedinahierarchy.Thetopcomputersystem(usuallyamainframe)controlstheentirenetwork.Allnetworktopologiesoperateaccordingtoestablishednetworkprotocolsthatpermitdifferenttypesofcomputerstocommunicateandinteroperate.InformationTechnologyArchitectureDataArchitecturesforDistributedRelationalDatabasesTheunderlyingtechnologyofclient/servercomputinghasmadeitpossibletodistributedatawithoutlossofcentralizedcontrol.Thiscontrolisbeingaccomplishedthroughdistributedrelationaldatabases.Arelationaldatabasestoresdatainatabularform.Eachfileisimplementedasatable.Eachfieldisacolumninthetable.Eachrecordsinthefileisarowinthetable.Relatedrecordsbetweentwotablesareimplementedbyintentionallyduplicatingcolumnsinthetwotables.Adistributedrelationaldatabasedistributesorduplicatestablestomultipledatabaseservers(andinrarecases,clients).InformationTechnologyArchitectureDataArchitecturesforDistributedRelationalDatabasesThesoftwarerequiredtoimplementdistributedrelationaldatabasesiscalledadistributedrelationaldatabasemanagementsystem.Adistributedrelationaldatabasemanagementsystem(ordistributedRDBMS)isasoftwareprogramthatcontrolsaccessto,andmaintenanceofthestoreddata.Italsoprovidesforbackup,recoveryandsecurity.Itissometimescalledaclient/serverdatabasemanagementsystem.InformationTechnologyArchitectureDataArchitecturesforDistributedRelationalDatabasesWhatsetsadistributedRDBMSapartfromaPCRDBMSisthedatabaseengine.ThedatabaseengineisthatpartoftheDBMSthatexecutesdatabasecommandstocreate,read,update,anddeleterecords(rows)inthetables.InaPCRDBMS,thedatabaseenginethatprocessesalldatabasecommandsmustexecuteontheclientPC,evenifthedataisactuallystoredontheserver.InadistributedRDBMS,thedatabaseenginethatprocessesalldatabasecommandsexecutesonthedatabaseserver.InformationTechnologyArchitectureDataArchitecturesforDistributedRelationalDatabasesTruedatadistributionpartitionsdatatooneormoredatabaseservers.Entiretablescanbeallocatedtodifferentservers,orsubsetsofrowsinatablecanbeallocatedtodifferentservers.AnRDBMScontrolsaccesstoandmanageseachserver.Datareplicationduplicatesdataononeormoredatabaseservers.Entiretablescanbeduplicatedondifferentservers,orsubsetsofrowsinatablecanbeduplicatedtodifferentservers.TheRDBMSnotonlycontrolsaccessto,andmanagementofeachserverdatabase—italsoensuresthatupdatesononeserverareupdatedonanyserverwherethedataisduplicated.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareBatchInput/Output:Inbatchprocessing,transactionsareaccumulatedintobatchesforperiodicprocessing.Thebatchinputsareprocessedagainstmasterfilesordatabases.Transactionfilesordatabasesmayalsobecreatedorupdatedbythetransactions.Mostoutputstendtobegeneratedtopaperormicroficheonascheduledbasis.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareOn-lineProcessing:Themajorityofsystemshaveslowlyevolvedfrombatchprocessingtoon-lineprocessing.On-linesystemsprovideforaconversationaldialoguebetweenuserandcomputer.Businesstransactionsandinquiriesareoftenbestprocessedwhentheyoccur.Errorsareidentifiedandcorrectedmorequickly.Transactionstendtobeprocessedearliersinceon-linesystemseliminatetheneedforbatchdatafilepreparation.On-linemethodspermitgreaterhumaninteractionindecisionmaking,evenifthedataarrivesinnaturalbatches.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareRemoteBatch:Remotebatchcombinesthebestaspectsofbatchandon-lineI/O.Distributedon-linecomputershandledatainputandediting.Editedtransactionsarecollectedintoabatchfileforlatertransmissiontohostcomputersthatprocessthefileasabatch.Resultsareusuallytransmittedasabatchbacktotheoriginalcomputers.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareKeylessDataEntry:Keyingerrorshavealwaysbeenamajorsourceoferrorsincomputerinputs(andinquiries).Inbatchsystems,keyingerrorscanbeeliminatedthroughopticalcharacterreading(OCR)andopticalmarkreading(OMR)technology.Therealadvancesinkeylessdataentryarecomingforon-linesystemsintheformofauto-identificationsystems.Barcodingsystems(similartouniversalproductcodesystemsthatarecommonplaceinthegroceryandretailindustries)arewidelyavailableformanymodernapplications.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewarePenInput:Somebusinessesusethistechnologyforremotedatacollection.Forexample,UPS.ApromisingtechnologyisemergingintheformofhandheldPCs(HPCs).Similartopersonalorganizersandpersonaldataassistants,theseHPCsoffergreatercompatibilitywithdesktopandlaptopPCs.BasedonMicrosoft’sWindowsCEoperatingsystem,theycanbeprogrammedtobecomedisconnectedclientsinaclient/serverapplication.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareGraphicalUserInterfaces:GUItechnologyhasbecometheuserinterfaceofchoiceforclient/serverapplications.GUIsdonotautomaticallymakeanapplicationbetter.PoorlydesignedGUIscannegatetheallegedadvantagesofconsistentuserinterfaces.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareGraphicalUserInterfaces:MostusersinterfacewiththeInternetviaaclientsoftwaretoolcalledabrowser.Thebrowserparadigmisbasedonhypertextandhyperlinks.Hypertextarekeywordsthatareclearlyhighlightedasalinktoanewpageofinformation.Hyperlinksarelinksfromgraphics,buttons,andareasthatlinktoadifferentpageofinformation.Theselinksmayiteasytonavigatefromtoandapplication-to-application.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareElectronicMessagingandWorkGroupTechnology:Informationsystemsarebeingdesignedtodirectlyincorporatetheelectronicmail.Forexample,MicrosoftOutlookandExchangeServerandIBM/LotusNotesallowfortheconstructionofintelligentelectronicformsthatcanbeintegratedintoanapplication.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareElectronicDataInterchange:Businessesthatoperateinmanylocationsandbusinessesthatseekmoreefficientexchangeoftransactionswiththeirsuppliersand/orcustomersoftenutilizeelectronicdatainterchange.Electronicdatainterchange(EDI)istheelectronicflowofbusinesstransactionsbetweencustomersandsuppliers.WithEDI,abusinesscaneliminateitsdependenceonpaperdocumentsandmail,plusdramaticallyreduceresponsetime..VariousEDIstandardsexistforthestandardizedexchangeofdatabetweenorganizationswithinthesameindustry.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareImagingandDocumentInterchange:SimilartoEDIexceptthattheactualimagesofformsanddataaretransmittedandreceived.Itisparticularlyusefulinapplicationsinwhichtheformimagesorgraphicsarerequired.(insuranceindustry)InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareMiddleware:Informationsystemsmustalsointerfacetootherinformationsystems.Systemintegrationistheprocessofmakingheterogeneousinformationsystems(andcomputersystems)interoperate.Akeytechnologyusedtointerfaceandintegratesystemsismiddleware.Middlewareisutilitysoftwarethatservestointerfacesystemsbuiltwithincompatibletechnologies.Middlewareservesasaconsistentbridgebetweentwoormoretechnologies.Itmaybebuiltintooperatingsystems,butitisalsofrequentlysoldasaseparateproduct.InformationTechnologyArchitectureInterfaceArchitectures-Inputs,Outputs,&MiddlewareSelectingUserandSystemInterfaceTechnologies:ThepreferredorapproveduserandsysteminterfacetechnologiesmaybespecifiedaspartoftheInterfacearchitecture.Anorganizationmayleaveinterfacetechnologiesasadecisiontobemadeonaproject-by-projectbasis.Anorganizationmayestablishmacroguidelinesforinterfacesandleavethemicrodecisionstoindividualprojects.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementThePROCESSarchitectureofanapplicationisdefinedintermsofthesoftwarelanguagesandtoolsthatwillbeusedtodevelopthebusinesslogicandapplicationprograms.Thisisexpressedasamenuofchoicessincedifferentsoftwaredevelopmentenvironments(SDEs)aresuitedtodifferentapplications.Asoftwaredevelopmentenvironmentisalanguageandtoolkitforconstructinginformationsystemapplications.TheyareusuallybuiltaroundoneormoreprogramminglanguagessuchasCOBOL,Basic,CorC++,Pascal,Smalltalk,orJava.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSDEsforCentralizedComputing&DistributedPresentation:Thesoftwaredevelopmentenvironmentforcentralizedcomputingconsistsof:Aneditorandcompiler,usuallyCOBOL,towriteprograms.Atransactionmonitor,usuallyCICS,tomanageon-linetransactionsandterminalscreens.Afilemanagementsystem,suchasVSAM,oradatabasemanagementsystem,suchasDB2.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSDEsforCentralizedComputing&DistributedPresentation:ThepersonalcomputerbroughtmanynewCOBOLdevelopmenttoolsdowntothemainframe.APC-basedCOBOLSDEprovidedtheprogrammerwithmorepowerfuleditors,andtestinganddebuggingtoolsattheworkstationlevel.AprogrammercoulddomuchofthedevelopmentworkatthePClevel,andthenuploadthecodetothecentralcomputerforsystemtesting,performancetuning,andproduction.TheSDEcouldbeinterfacedwithaCASEtoolandcodegeneratortotakeadvantageofprocessmodelsdevelopedduringsystemsanalysis.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSDEsforCentralizedComputing&DistributedPresentation:SDEsprovidetoolstodevelopdistributedpresentationclient/server.TheMicroFocusDialogManagerprovidedCOBOLWorkbenchuserswithtoolstobuildWindows-baseduserinterfacesthatcouldcooperatewiththeCICStransactionmonitorsandthemainframeCOBOLprograms.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSDEsforTwo-TierClient/Server:TheSDEfortwo-tieredclient/serverapplications(alsocalleddistributeddata)consistsofaclient-basedprogramminglanguagewithbuilt-inSQLconnectivitytooneormoreserverdatabaseengines.SDEsprovidethefollowing:Rapidapplicationdevelopment(RAD)forquicklybuildingthegraphicaluserinterfacethatwillbereplicatedandexecutedonalloftheclientPCs.AutomaticgenerationofthetemplatecodefortheaboveGUIandassociatedsystemevents(suchasmouse-clicks,keystrokes,etc.)thatusetheGUI.Theprogrammeronlyhastoaddthecodeforthebusinesslogic.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSDEsforTwo-TierClient/Server:SDEsprovidethefollowing:(continued)AprogramminglanguagethatiscompiledforreplicationandexecutionontheclientPCs.Connectivity(intheabovelanguage)forvariousrelationaldatabaseengines,andinteroperabilitywiththoseengines.InteroperabilityisachievedbyincludingSQLdatabasecommands(to,forexample,create,read,update,delete,andsortrecords)thatwillbesenttothedatabaseengineforexecutionontheserver.Asophisticatedcodetestinganddebuggingenvironmentfortheclient.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSDEsforTwo-TierClient/Server:SDEsprovidethefollowing:(continued)Asystemtestingenvironmentthathelpstheprogrammerdevelop,maintain,andrunareusabletestscriptofuserdata,actions,andeventsagainstthecompiledprogramstoensurethatcodechangesdonotintroduceneworunforeseenproblems.Areportwritingenvironmenttosimplythecreationofnewend-userreportsoffaremotedatabase.AhelpauthoringsystemfortheclientPCs.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSDEsforMultiTierClient/Server:Unliketwo-tiedapplications,n-tieredapplicationsmustsupportmorethan100userswithmainframe-liketransactionresponsetimeandthroughput;with100gigabyteorlargerdatabases.TheSDEsinthisclassmustprovidetheallofthecapabilitiestypicallyassociatedwithtwo-tieredSDEsplusthefollowing:Supportforheterogeneouscomputingplatforms,bothclientandserver,includingWindows,OS/2,UNIX,Macintosh,andlegacymainframesandminicomputers.Codegenerationandprogrammingforbothclientsandservers.Mosttoolsinthisgenresupportpureobject-orientedlanguagessuchasC++andSmalltalk.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSDEsforMultiTierClient/Server:TheSDEsinthisclassmustprovidetheallofthecapabilitiestypicallyassociatedwithtwo-tieredSDEsplusthefollowing:(continued)Astrongemphasisonreusabilityusingsoftwareapplicationframeworks,templates,components,andobjects.Bundledmini-casetoolsforanalysisanddesignthatinteroperatewithcodegeneratorsandeditors.Toolstohelpanalystsandprogrammerspartitionapplicationcomponentsbetweentheclientsandservers.Toolstohelpdevelopersdeployandmanagethefinishedapplicationtoclientsandservers.Thisgenerallyincludessecuritymanagementtools.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSDEsforMultiTierClient/Server:TheSDEsinthisclassmustprovidetheallofthecapabilitiestypicallyassociatedwithtwo-tieredSDEsplusthefollowing:(continued)Abilitytoautomatically‘‘scale’theapplicationtolargeranddifferentplatforms,clientandserver.Thisissueofscalabilitywasalwaysassumedinthemainframecomputingera,butisrelativelynewtotheclient/servercomputingera.Sophisticatedsoftwareversioncontrolandapplicationmanagement.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSDEsforInternetandIntranetClient/Server:Mostoftheserapidapplicationdevelopmenttoolsarebuiltaroundthreecorestandardtechnologies:HTML(HypertextMarkupLanguage)—thelanguageusedtoconstructworldwidewebpagesandlinks.CGI(ComputerGraphicsInterface)—alanguageforpublishinggraphicalworldwidewebcomponentsandlinksJava—ageneralpurposeprogramminglanguageforcreatingplatform-independentprogramsandappletsthatcanexecuteacrosstheworldwideweb.TheseSDEscancreatebothInternet,intranet,andnon-Internet/intranetapplications.InformationTechnologyArchitectureProcessArchitecture-TheSoftwareDevelopmentEnvironmentandSystemManagementSystemManagement:Client/servercomputingapplicationsusuallyrequireoneormoreofthefollowingcommonprocessdevelopmentandmanagementtools:TransactionProcessing(TP)Monitors—softwarethatensuresthatallofthedataassociatedwithasinglebusinesstransactionisprocessedasasingletransactionamongstall