ENHANCINGXML-CACHEEFFICIENCYBYXMLCOMPRESSIONStefanBöttcher,LarsFernhombergandRitaHartelUniveristyofPaderborn,ComputerScience,Fürstenallee11,33102Paderborn,Germany{stb,lafe,rst}@uni-paderborn.deKeywords:XMLdatabases,Caching,Compression.Abstract:WheneveraclientwithlimitedresourcesfrequentlyhastoretrievelargepartsofahugeXMLdocumentthatisstoredonaremotewebserver,dataexchangefromtheservertotheclientincombinationwithre-strictedbandwidthmaybecomeaseriousbottleneck.Wepresentanapproachthatcombinestheadvantagesofcachingwiththeadvantagesofquery-capableandupdatableXMLcompression.Weprovideaperfor-manceevaluationthatdemonstratesthatthecombinationofthetwotechniques–cachingandcompression–yieldsabenefitintermsoflessdatavolumetobetransferredaswellasintermsofareducedanswertimefortheuser.Theperformanceevaluationdemonstratesthatcombiningbothtechniqueyieldsanevenstrong-erbenefitthaneachtechniquealone.1INTRODUCTIONOurapproachcombinesbothtechniquesasfol-lows:wecompressthedataonthewebserverand1.1Motivationprocessandtransfertheminthecompressedformattotheclient.Ontheclientside,thedataisthenInthelastyears,moreandmorestandardsfordatacachedincompressedformat,suchthatitcanbeusedforansweringnotonlyidenticalbutalsosimi-exchangehaveevolvedthatarebasedontheflexiblehierarchicaldataformatXML.Examplesforsuchlarquerieswithoutaccesstothewebserver.dataformatsareSEPA(SingleEuropeanPaymentArea)forthefinancialsectororOTA(OpenTravel1.2ContributionsAlliance)fortheflightsector.Whereaspreviously,theclientsthatparticipatedThispaperproposesanapproachforintegratingininternet-basedapplicationsgotstrongerresources,cachingandcompressioninordertoreducedatanowareversedevelopmentcanbeobserved.Moretransfervolumeandtimeandthatcombinestheandmoresmallmobiledevices(likee.g.PDAsandfollowingproperties:smartphones)thatcomewithrestrictedinternalre--Itcompressesthestructureandtheconstantdatasourcesandrestrictedconnectionbandwidthpartici-oftheXMLdocumentonserverside.pateinwebapplications.-Ittransf