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）

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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