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专业外文翻译1题目ProgrammingOverlayNetworkswithOverlaySocketsProgrammingOverlayNetworkswithOverlaySocketsTheemergenceofapplication-layeroverlaynetworkshasinspiredthedevelopmentofnewnetworkservicesandapplications.Researchonoverlaynet-workshasfocusedonthedesignofprotocolstomaintainandforwarddatainanoverlaynetwork,however,lessattentionhasbeengiventothesoftwaredevelopmentprocessofbuildingapplicationprogramsinsuchanenvironment.Clearly,thecomplexityofoverlaynetworkprotocolscallsforsuitableapplicationprogramminginterfaces(APIs)andabstractionsthatdonotrequiredetailedknowledgeoftheoverlayprotocol,and,thereby,simplifythetaskoftheapplicationprogrammer.Inthispaper,wepresenttheconceptofanoverlaysocketasanewprogrammingabstractionthatservesastheendpointofcommunicationinanoverlaynetwork.Theoverlaysocketprovidesasocket-basedAPIthatisindependentofthechosenoverlaytopology,andcanbeconfiguredtoworkfordifferentoverlaytopologies.TheoverlaysocketcansupportapplicationdatatransferoverTCP,UDP,orothertransportprotocols.ThispaperdescribesthedesignoftheoverlaysocketanddiscussesAPIandconfigurationoptions.1IntroductionApplication-layeroverlaynetworks[5,9,13,17]provideflexibleplatformsfordevelop-ingnewnetworkservices[1,10,11,14,18–20]withoutrequiringchangestothenetwork-layerinfrastructure.Membersofanoverlaynetwork,whichcanbehosts,routers,servers,orapplications,organizethemselvestoformalogicalnetworktopology,andcommu-nicateonlywiththeirrespectiveneighborsintheoverlaytopology.Amemberof专业外文翻译2anoverlaynetworksendsandreceivesapplicationdata,andalsoforwardsdataintendedforothermembers.Thispaperaddressesapplicationdevelopmentinoverlaynetworks.Weusethetermoverlaynetworkprogrammingtorefertothesoftwaredevelopmentprocessofbuildingapplicationprogramsthatcommunicatewithoneanotherinanapplication-layeroverlay_ThisworkissupportedinpartbytheNationalScienceFoundationthroughgrantANI-0085955..network.Thediversityandcomplexityofbuildingandmaintainingoverlaynetworksmakeitimpracticaltoassumethatapplicationdeveloperscanbeconcernedwiththecomplexityofmanagingtheparticipationofanapplicationinaspecificoverlaynetworktopology.Wepresentasoftwaremodule,calledoverlaysocket,thatintendstosimplifythetaskofoverlaynetworkprogramming.Thedesignoftheoverlaysocketpursuesthefollowingsetofobjectives:First,theapplicationprogramminginterface(API)oftheoverlaysocketdoesnotrequirethatanapplicationprogrammerhasknowledgeoftheoverlaynetworktopology.Second,theoverlaysocketisdesignedtoaccommodatedif-ferentoverlaynetworktopologies.Switchingtodifferentoverlaynetworktopologiesisdonebymodifyingparametersinaconfigurationfile.Third,theoverlaysocket,whichoperatesattheapplicationlayer,canaccommodatedifferenttypesoftransportlayerprotocols.Thisisaccomplishedbyusingnetworkadaptersthatinterfacetotheun-derlyingtransportlayernetworkandperformencapsulationandde-encapsulationofmessagesexchangedbytheoverlaysocket.CurrentlyavailablenetworkadaptersareTCP,UDP,andUDPmulticast.Fourth,theoverlaysocketprovidesmechanismsforbootstrappingnewoverlaynetworks.Inthispaper,weprovideanoverviewoftheoverlaysocketdesignanddiscussover-laynetworkprogrammingwiththeoverlaysocket.Theoverlaysockethasbeenimple-mentedinJavaaspartoftheHyperCast2.0softwaredistribution[12].Thesoftwarehasbeenusedforvariousoverlayapplications,andhasbeentestedinbothlocal-areaaswellaswide-areasettings.TheHyperCast2.0softwareimplementstheoverlaytopolo-giesdescribedin[15]and[16].Thispaperhighlightsimportantissuesoftheoverlaysocket,additionalinformationcanbefoundinthedesigndocumentationavailablefrom[12].Severalstudiesbeforeushaveaddressedoverlaynetworkprogrammingissues.Even专业外文翻译3earlyoverlaynetworkproposals,suchasYoid[9],Scribe[4],andScattercast[6],havepresentedAPIsthataspiretoachieveindependenceoftheAPIfromtheoverlaynetworktopologyused.Particularly,YoidandScattercastuseasocket-likeAPI,how-ever,theseAPIsdonotaddressissuesthatarisewhenthesameAPIisusedbydifferentoverlaynetworktopologies.Severalworksonapplication-layermulticastoverlaysinte-gratetheapplicationprogramwiththesoftwareresponsibleformaintainingtheoverlaynetwork,withoutexplicitlyprovidinggeneral-purposeAPIs.TheseincludeNarada[5],Overcast[13],ALMI[17],andNICE[2].Arecentstudy[8]hasproposedacommonAPIfortheclassofso-calledstructuredoverlays,whichincludesChord[19],CAN[18],andBayeux[20],andotheroverlaysthatwereoriginallymotivatedbydistributedhashtables.Ourworkhasadifferentemphasisthan[8],sinceweassumeascenariowhereanapplicationprogrammermustworkwithseveral,possiblyfundamentallydif-ferent,overlaynetworktopologiesanddifferenttransmissionmodes(UDP,TCP),and,therefore,needsmechanismsthatmakeiteasytochangetheconfigurationoftheun-derlyingoverlaynetwork..InternetOverlaysocketApplicationOverlaysocketApplicationApplicationOverlaysocketApplicationApplicationOverlaysocketApplicationOverlayNetwork.Fig.1.Theoverlaynetworkisacollectionofoverlaysockets.Root(sender)Root(receiver)(a)Multicast(b)Unicast.Fig.2.Dataforwardinginoverlaynetworks.Therestofthepaperisorganizedasfollowing.InSection2weintroducecon-cepts,abstractions,andterminolog