网上商城---文献翻译原文

JSPSplittingforImprovingExecutionPerformanceTakuyaNakaikeIBMJapan,Ltd.1623-14,Shimotsuruma,Yamato-shi,Kanagawa-ken242-8502,[e-mail],Ltd.1623-14,Shimotsuruma,Yamato-shi,Kanagawa-ken242-8502,[e-mail]an,Ltd.1623-14,Shimotsuruma,Yamato-shi,Kanagawa-ken242-8502,[e-mail]pan,Ltd.1623-14,Shimotsuruma,Yamato-shi,Kanagawa-ken242-8502,[e-mail]n,Ltd.1623-14,Shimotsuruma,Yamato-shi,Kanagawa-ken242-8502,[e-mail](JavaServerPages)pageintofragmentscanimprovetheexecutionperformanceofJSPpageswhentheWebapplicationservercanseparatelycachetheWebpagefragmentsobtainedbyexecutingtheJSPfragments.IfaJSPpageissplitintofragmentsaccordingtotheupdatefrequencyofeachportionoftheWebpageobtainedbyex-ecutingtheJSPpage,allofthesplitJSPfragmentsdonotneedtobeexecutedagainwhenonlyasinglecachedpartofaWebpageexpires.Inaddition,thefragmentsofaJSPpagecanbereusedbyotherJSPpages.Inbothcases,theexecutionresultsofalloftheJSPfragmentssplitfromtheJSPpagemustbethesameasfromtheJSPpagebeforeitwassplit.Inthispaper,weproposeJSPsplitting,whichisamethodofsplittingaJSPpageintofragmentsmaintain-ingthedataandcontroldependencesexistingintheorig-inalJSPpage.JSPsplittingautomaticallydetectsthepor-tionsneededtomaintainthedataandcontroldependencesofaJSPpagefortheportionsthatdeveloperswanttosplitfromtheJSPpage.WeimplementedJSPsplittingwithaGUItool,andconfirmedthatthesplitJSPfragmentswereexecutedinthesameasthewayastheJSPpagebeforethesplit.ExperimentalresultsshowthattheresponsetimetoaccessaWebpagecanbereducedbysplittingaJSPpageintofragmentsandsettingdifferentcachingperiodsfortheWebpagefragmentsobtainedbyexecutingtheJSPfrag-ments.1.IntroductionSplittingaJSP(JavaServerPages)[7]pageintofrag-mentscanimprovetheexecutionperformanceofsomeJSPpageswhentheWebapplicationservercanseparatelycachetheWebpagefragmentsobtainedbyexecutingthefrag-mentsoftheJSPpage.TheperiodofcachingdynamicWebpagesgeneratedbyaJSPengineislimitedduetothedy-namicnatureofthecontent.WhenthecachedcontentofaWebpagegeneratedbyaJSPengineisupdated,theentireJSPpagemustbeexecutedagainontheapplicationserver,eventhoughthechangeoftheWebpagemightbesmall.SincefrequentupdatesofcachedWebpagesincreasetheloadonanapplicationserver,itisreasonabletosplitaJSPpageintofragmentsandsetdifferentcachingperiodsfortheWebpagefragmentsobtainedbyexecutingtheJSPfrag-ments.Ofcourse,theWebpagefragmentsmustbemergedintoafinalWebpagecorrectly.TheDynacachetechnologyofIBMWebSphereApplicationServer[9]allowsWebpagefragmentstohavedifferentcachingperiods.Cachetagli-brariesprovidedbytheApacheJakartaProject[3]alsosup-portdifferentcachingperiodsfortheJSPfragments.Inad-dition,ESI(EdgeSideIncludes)[1]technologyprovidesamechanismtocacheWebpagefragmentswithdifferentcachingperiods,andtomergethemintoafinalWebpageonanedgeserver.TheapplicationoffloadtechnologyofIBMWebSphereEdgeServer[8]isanotherapproachtoimprovetheexecu-tionperformanceofJSPpages.ThistechnologyallowsoneormoreJSPfragmentstobecachedandexecutedonedgeservers.TheremainingJSPfragmentsaredeployedontheProceedingsofthe2004InternationalSymposiumonApplicationsandtheInternet(SAINT’04)0-7695-2068-5/04$20.00©2004IEEEapplicationserverandarecalledbytheJSPfragmentsexe-cutedontheedgeserver.Thus,someoftheexecutionofaJSPpageisoffloadedtotheedgeserver.SplittingaJSPpagefacilitatesthereuseofJSPfrag-ments.WhenaWebapplicationconsistsofmanyJSPpages,thesameportionstendtoexistinmanyJSPpages.Exam-plesaretheframes,thebanners,theheaders,andetc..WhenaJSPpageissplitintofragments,thetotalexe-cutionresultofallofthefragmentsmustbethesameastheJSPpagebeforeitwassplit.Inaddition,whenthefrag-mentsofaJSPpageareexecutedindifferentservers,eachfragmentneedstobeexecutedwithouttheotherfragments.Inordertosatisfytheseconditions,weproposeJSPsplit-ting,whichisthemethodofsplittingaJSPpageintofrag-mentsdescribedinthispaper.Sinceitisverydifficulttoau-tomaticallyfindthebestwaytosplitaJSPpageintofrag-mentsforsomeparticularpurpose,weassumethatthede-veloperswillselecttheportionsthattheywanttosplitintofragments.InordertoexecuteallofthedividedJSPpagescorrectly,JSPsplittingautomaticallydetectsanyportionsthatmustbemovedorcopiedintoafragmentwiththese-lectedportions.Thedetectionisdonebasedontheanaly-sisofthedataandcontroldependencesexistinginaJSPpage.JSPsplittingissimilartotheprogramslicingtech-nique[13]thatslicesaprogrambasedonthedataandthecontroldependences.However,theprogramslicingtech-niquedoesnottakeintoaccountthattheslicedprogramsareexecutedindependentlyandthatthetotalexecutionre-sultoftheslicedprogramsmustbethesameasthepro-grambeforethedivision.Inaddition,sincedataispassedtotheJSPengineduringtheexecutionofJSPpages,thesourceprogramoftheJSPengine,suchasApacheTom-cat[4],isrequiredinordertoanalyzethedatadependencescorrectly.Thisisimpractical,becausethesourceprogramoftheJSPengineisverylargeandcomplex.JSPsplittingavoidstheanalysisoftheJSPenginebyutilizingthechar-acteristicsofJSP.Therestofthepaperiso