




已阅读5页,还剩3页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
FutureGenerationComputerSystems15(1999)417424EfficiencyofstandardsoftwarearchitecturesforJava-basedaccesstoremotedatabasesN.Zingirian,M.Maresca,S.NalinDipartimentodiElettronicaedInformatica,UniversityofPadua,Padua,ItalyAccepted14December1998AbstractNovelclientserverarchitecturesforremotedatabaseaccessareincreasinglytakingadvantageofWebtechnology,adoptingWebbrowsersasgraphicuserinterfacesintheclientsandtraditionalSQLdatabasemanagementsystems(DBMSs)intheservers.Theinter-operationbetweenstandardbrowsersandspecificDBMSsistodaysupportedbyanumberofsoftwarearchitecturesbasedontheJavavirtualmachineembeddedinlastgenerationbrowsers.Unfortunatelysuchsoftwarearchitec-tures,whichappearexcellentfromthepointsofviewofopennessandflexibility,introduceconspicuouslatenciesindatabaseaccess.Theobjectiveofthispaperistoidentifysuchlatenciesthroughtheanalysisofanumberofexperimentalresults.ThepaperdescribesfourdifferentsoftwarearchitecturessupportingJava-basedSQLdatabaseaccess,reportstheirperformancemeasurementsondifferenthardwareplatformsandcomparestheresultsobtained.c1999ElsevierScienceB.V.Allrightsreserved.Keywords:CORBA;Java;JDBC;Performanceevaluation;Visualdatabaseaccess1.IntroductionThetraditionalapproachtoclientserverdatabaseaccessisbasedonthecombinedactionofauserinterfacewritteninavisuallanguage(i.e.theclient)andastandardSQLengine(i.e.theserver).Currently,thisapproachischallengedbynovelsolutionsbasedontheemergingWebparadigm1.IntheWeb-basedsolutionstheuserinterface,typicallywritteninJava,isdownloadedbyabrowserfromtheserverandrunsonthebrowservirtualmachine.Themainpointofsuchsolutionsisthattheclientsoftwareresidesintheserversystemasauniquecopy,ratherthanbeingreplicatedintheclientsystems.Thisfactallowsthecostsofinstallation,configurationandmaintenanceoftheclientsoftwaretobereducedthankstothepossibilityofcentralisingalltheseoperationsattheserversite2.Web-basedaccesstoSQLdatabasescanbesupportedbyanumberofsoftwarearchitectures3characterizedbyadifferentcompositionofasetofbasiccomponents4.Unfortunatelysuchsoftwarearchitectures,whichappearexcellentfromthepointofviewofopennessandflexibility,introduceconspicuouslatenciesindatabaseaccess.Correspondingauthor.0167-739X/99/$seefrontmatterc1999ElsevierScienceB.V.Allrightsreserved.PII:S0167-739X(98)00085-5418N.Zingirianetal./FutureGenerationComputerSystems15(1999)417424Fig.1.Softwarearchitecture1:databaseaccessthroughJavasockets.TheobjectiveofthestudypresentedinthispaperistodescribefourdifferentsoftwarearchitecturesimplementingWeb-basedSQLdatabaseaccessandtoreportandcomparetheirperformances,characterizingthesourcesofthelatenciesintroducedbyeacharchitecture.Thepaperisorganizedasfollows.FirstwedescribethestandardsoftwarearchitecturesforJava-baseddatabaseaccess(Section2).Thenwepresentthetestbedusedandthemethodologyfollowedinourexperiments(Section3).Finallywepresenttheresultsoftheexperiments(Section4)anddiscusstheperformanceprofileofthesoftwarearchitecturestested(Section5).Abriefsummary(Section6)concludesthepaper.2.SoftwarearchitecturesforJava-baseddatabaseaccessInthissectionwepresentthefoursoftwarearchitecturesforJava-baseddatabaseaccessthatweselectedforourinvestigation.Eacharchitecturecomplieswiththeclientserverparadigmandconsistsofthreemainentities:theclient,theserverandtheinter-operabilitycomponents.Theclientandtheserverarethesameineacharchitecture;theinter-operabilitycomponentsarethedistinctivefeatureforeacharchitecture.TheclientisaJava-enabledbrowser,theserverisaSQLdatabasemanagementsystem(DBMS)whichacceptsremotenetworkconnectionsandqueries.WeassumethatthenetworkprotocolstackisbasedontheTCP/IPprotocolsuite.Theinter-operabilitycomponentsofeachsoftwarearchitecturearedescribedintherestofthesection.2.1.ArchitecturebasedonJavasocketconnectivitymodulesTheschemeofthearchitecturebasedonJavasocketconnectivitymodulesisdepictedinFig.1Theshadedblocksrepresentthesoftwaremodulesthattheprogrammerhastodeveloptointerconnecttheexistingcomponents.Theclient(browser)downloadsanappletfromtheservermachineandrunsit.TheappletsendsthequeriesandreceivestheresponsesthroughtheJavasocketmodules.Theserver(DBMS)exchangesdatawiththeclientthroughasoftwarecomponentthatactsasanintermediatecustomagent.SuchanintermediatecustomagentreceivestheclientqueriesandsubmitsthemtothedatabasethroughthedatabaseAPIlibrary.TheconnectivitybetweentheappletandthecustomagentisbasedonTCP/IP.OntheclientsidecommunicationissupportedbythestandardJavasocketAPI;ontheserversidecommunicationissupportedbythestandardUNIXsocketinterface.Inter-operationbetweentheappletandthecustomagentisbasedonacustomprotocolwhichsupportsthefundamentaldatabaseaccessoperations(opendatabase,submitquery,retrieveresponse,closedatabase).2.2.ArchitecturebasedonproprietaryDBMSJDBCdriverTheArchitecturebasedonproprietaryDBMSJDBCdriverisdepictedinFig.2.JavadataBaseconnectivity(JDBC)isastandardinterfacewhichallowsJavaappletsandapplicationstointer-operatewithdatabase.LikeinN.Zingirianetal./FutureGenerationComputerSystems15(1999)417424419Fig.2.SoftwarearchitecturefordatabaseaccessbasedonDBMSproprietaryJavaJDBC.Fig.3.SoftwarearchitecturefordatabaseaccessbasedonJavaJDBCandrequestbroker.thepreviousarchitecture,theclient(browser)downloadsanappletfromtheservermachineandrunsit.TheappletaccessestheDBMSthroughthestandardprimitivesoftheJBDBCapplicationprogramminginterface(JDBCAPI).TheJDBCAPIisavailableasapartofthestandardclassesoftheJavadeveloperkitsandoftheJava-enabledbrowserscompliantwitthelatestversionsofJava.TheJDBCclassesarenotspecificforanyparticularDBMS,exceptforoneclass,denotedtheJDBCdriver,whichimplementsthecommunicationprotocolrequiredbythespecificDBMSwhichitrefersto.ThespecificJDBCdriversareprovidedbytheDBMSvendorsorbythirdpartiesandaredynamicallylinkedtothestandardJDBCobjects.UsuallytheJDBCdriverisdownloadedfromtheserveralongwiththeclientapplet.TheDBMSdriverinteroperateswiththeDBMSoverthenetworkbytranslatingtheJDBCmethodsinproprietarymessagestoproprietaryservicerequestmessages.Theserver(DBMS)receivesthequeries,sendstheresponsesandperformsalltheoperationsthroughitsproprietaryprotocol,withnoneedofadditionalinter-operabilitymodulesintheservermachine.2.3.ArchitecturebasedonJDBCrequestbrokermiddlewareThearchitecturebasedonarequestbrokerisdepictedinFig.3.Asinthepreviousarchitecture,theappletcommunicateswiththedatabasethroughthestandardJDBCAPIandthroughaspecificJDBCdriver.Asopposedtothepreviousarchitecture,theJDBCdriverdoesnotaccessthedatabasedirectlybutitaccessanintermediateobject,calledthebroker,runningontheservermachine,throughaproprietaryprotocol.Whentheappletrequestsaconnection,therequestbrokerdynamicallyinstantiatestwocomponents:aJDBCagent,andadatabaseagentspecificfortheDBMSadopted.Theserver(DBMS)andtheclientinter-operatethroughthedatabaseagentandthroughtheJDBCagentwhichinteractbymeansofaproprietaryprotocol.Theopennessandflexibilityadvantagesofusingtherequestbrokerandtheagentsarediscussedin5.420N.Zingirianetal./FutureGenerationComputerSystems15(1999)417424Fig.4.SoftwarearchitecturefordatabaseaccessbasedonCORBA.Table1SoftwareproductsusedascomponentsofthetestedsoftwarearchitecturesSoftwarecomponentSoftwareproductVendorDBMS1PostgreSQL6.1.1UniversityofCalifornia7BrowserNavigator4NetscapeJ.socketNetscapeDBMSJDBCdriverclasspostgresql.driverUniversityofCaliforniaRequestbrokeroplrqbOpenlinkDatabaseagentpgr95svOpenlinkJDBCagentjdbcsvOpenlinkBrokerJDBCDriverclassopenlink.driverOpenlinkClientORBpackageorg.omg.CORBAVisigenic/NetscapeServerORBomniORB2Olivetti&OracleResearchLabs2.4.ArchitecturebasedonCORBAinter-operabilitycomponentsTheCORBA-basedarchitectureisshowninFig.4.EveninthiscasetheappletcommunicateswiththeDBMSthroughanobject-orientedAPI.ThisAPIinstantiatesandinter-operateswithadatabaseaccessobjectwhichresidesintheservermachine.Inter-operabilityissupportedbyapairoflibrariescalledobjectrequestbrokers(ORBs)6whichcommunicatethroughtheInternetInter-ORBprotocol(IIOP).OneORBisaJavapackagelocatedintheclientmachinewhiletheotherORBisalibrarylocatedintheservermachine.Theserver(DBMS)communicateswiththedatabaseaccessobjectthroughtheDBMSapplicationprogramminginterface.ThedatabaseaccessobjectisdevelopedbythesystemintegratoranditsAPIisdescribedthroughaformalspecificationlanguagedenotedasinerfacedescriptionlanguage(IDL).TheIDLsup
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 社交媒体数据分析实习周记范文
- 新人教版小学音乐四年级上册教案计划
- 苏教版数学七年级分层教学计划
- 二年级上学期班级心理健康辅导计划
- 全县学校教育改革校长交流发言稿范文
- 幼儿园大班班主任教学创新计划
- 钢筋混凝土条形基础施工成本控制流程
- 幕墙设计供应链质量保证措施
- 家庭触电事故应急预案范文
- 地震灾害应急预案演练记录及计划
- 士官转业考试试题及答案
- GA/T 751-2024公安视频图像屏幕显示信息叠加规范
- 肺结节治疗的方法
- 公立医院DRG管理工作制度
- uom无人机考试试题及所有答案
- 2025-2030中国托法替尼行业市场发展趋势与前景展望战略分析研究报告
- 虾塘转让合同协议
- 金矿居间合同协议
- DB61T378-2006 主要造林树种苗木质量分级
- 基础护理学课件:肌肉注射操作
- 信息化环境下建筑工程档案管理路径研究
评论
0/150
提交评论