an adaptive causal ordering algorithm suited to mobile computing environmentsnew

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1、AnAdaptiveCausalOrderingAlgorithmSuitedtoMobileComputingEnvironmentsRaviPrakashMichelRaynalDepartmentofComputerScienceIRISAUniversityofRochesterCampusdeBeaulieuRochester,NY14627-0226,U.S.A.RennesCedex,France.prakash@cs.rochester.edumichel.raynal@irisa.frMukeshSinghalDept.ofComputerandIn

2、fo.ScienceTheOhioStateUniversityColumbus,OH43210,U.S.A.singhal@cis.ohio-state.eduAbstractCausalmessageorderingisrequiredforseveraldistributedapplications.Inordertopreservecausalordering,onlydirectdependencyinformationbetweenmessages,withrespecttothedestinationprocess(es),needbesentwithe

3、achmessage.Byeliminatingotherkindsofcontrolinformationfromthemessages,thecommunicationoverheadscanbesignicantlyreduced.Inthispaperwepresentanalgorithmthatusesthisknowledgetoecientlyenforcecausalorderingofmessages.Theproposedalgorithmdoesnotrequireanypriorknowledgeofthenetworktopologyo

4、rcommunicationpat-tern.Ascomputationproceeds,itacquiresknowledgeofthecommunicationpatternandiscapableofhandlingdynamicallychangingmulticastcommunicationgroups,andminimizingthecommunicationoverheads.Withregardtocommunicationoverheads,thealgorithmisoptimalforthebroadcastcommunicationcase.

5、Extensivesimulationexperimentsdemonstratethatthealgorithmimposeslowercommunicationoverheadsthanpreviouscausalorderingalgorithms.Thealgorithmcanbeemployedinavari-etyofdistributedcomputingenvironments.Itsenergyeciencyandlowbandwidthrequirementmakeitespeciallysuitableformobilecomputingsys

6、tems.Weshowhowtoemploythealgorithmforcausallyorderedmulticastingofmessagesinmobilecom-putingenvironments.Keywords:Causalmessageordering,directdependency,mobilecomputing.1IntroductionAdistributedsystemiscomposedofasetofprocessorsconnectedtoeachotherbyacom-municationnetwork.Theprocessorsd

7、onothaveaccesstoaglobalclockandtheydonothaveanysharedmemorythatcanbeusedtoexchangeinformation.Miniaturizationofcom-putersandadvancementsincommunicationtechnologyarebeingre ectedintheformofanincreasingnumberofmobileprocessingunitsinadistributedsystem.Amobilecomputingsystemisadis