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1、delphi三层架构开发基本概念介绍(Delphi三层架构开发基本概念介绍)IntroductiontothebasicconceptsofDelphithreetierarchitecturedevelopmentThreetierclient/serverOne:advantages:flexibilityandscalability.Reasonsforapplyingthreetierdevelopmenttechnology(distributed)(Bibliography:Delphi5.xdistributedmultitierapplicatio
2、nsystem)One:tosolvetheclient/serverstructuremaintenancecostproblem,improvetheclient/serverstructurescalabilityproblem.Thenumberofuserssupportedbyclient/serverstructurehasacertainlimit(below200persons).ThestructurerestrictsthedevelopmentofInternet/Intranetande-commerce.Thethreetierdeve
3、lopmentusesDatabasePooling,Objectpooling,ResourcePooling,threadingmodeprovidesahighdegreeofscalability.Two:solvetheproblemofreuseofapplicationlogic.Forexample,whenanenterprisewantstoaddWebbrowsingservicestotheoriginalclient/serverstructure,itisnecessarytoconfiguretheWebserver,rewritea
4、llapplicationlogic,andupdatetheMISsystem.Inthethree-tierstructure,COM/DCOM,CORBA(CommonObjectRequestBrokerArchitecture)orEnterpriseJavaobject,Bean,encapsulatebusinesslogic(calledenterpriseobject),cansolvetheaboveproblem.Greatlyreducethecostofdevelopmentandmaintenance.Three:theneedtoin
5、tegratedifferentsystemstructures,theneedfortimelyapplicationofnewtechnologies.Two:thethreetierservicemodelofMicrosoft1:structure:WindowsDNA(DistributedInternetapplications,distributedintranets)COM(componentobjectmodel,componentobjectmodel)componentasatooltoimplementsystemandapplicatio
6、nservices.LuserserviceLserviceLdataservice(1)userservices:WindowsDNAdefinesfourtypesofclientsthatcanbeusedtoimplementuserservices:Nstandardbrowsingcustomers:relyonsimple,pagebasedHTMLtomanagedatarepresentationanduserinteraction.Itscompatibilityisgood,notrichinfunction.Theadvantagesofs
7、pecialbrowsers(ex:DynamicHTML,scriptsandActiveXcontrols)tomaximizetherichnessandfunctionalityofuserinterfacesareapplicabletocompanyintranetNdependentInternetclients:integrateaccesstotheInternetandaccesstotheoperatingsystemontheclientmachine.NenhancedInternetclients:MicrosoftOffice97an
8、dMicr