Therestofthispaperisorganizedasfollows.Section2presentssomeoftherelevantbackground.Section3presentsourproposedapproach.Section4presentsresultsofoursimulationstudieshighlightingbene tsofcontentawarenessinthenetworkfollowedbyourconclusion.
atedassemblylanguagecalledSpannertoencodeacom-pleteprogramintoasingleIPv4orIPv6datagram.TheSwitchWareproject[4]takesasimilarapproachutilizingaspecializedlanguagecalledPLANwhosecapabilitiesarerestrictedtoonlyperforming“safe”operationsonanynode.ANTS[34]utilizesacombinationofmobilecode,demandloadingandcaching.Similartotheothermodels,anANTSnetworkconsistsofnodesrunninganANTSplatform,pack-etsarereplacedwithsmartcapsulescapableofexpressingmainlyforwardingroutinesandmechanismsarebuiltintothemodelforon-demandcodedissemination.Othersim-ilarapproaches[19]havefocusedonensuringquickjust-in-timecompilationofdownloadedcodetooptimizetheirperformancealongwithstaticlanguageveri cation.TheActiveSignalingProtocol(ASP)[13]takesadifferentap-proachtoactivenetworksbygoingawayfromthecapsulemodelandhavingdatapacketscarryareferencetosomeportablecodewhichcanbedownloadedonthe yandrunonanASPExecutionEnvironmentasnecessarytoenableanewactiveapplication.ActiveServices[5]takesanal-ternatemodeltointroductionofintelligenceintothenet-workbyrestrictingtheintelligencemainlytotheapplica-tionlayertherebypreservingtheroutingandforwardingse-manticsoftheInternetarchitecture.Asimilarapplicationlevelprocessingofuser-dataisconsideredin[10]tohandlecongestioncontrolinthenetwork.Thearchitectureallowsforapplicationstospecifyintra-networkprocessingbyus-ingActiveProcessingFunctionIdenti ers(APFI)sothatbandwidthallocatedcanbeintelligentlyreducedinaman-nertailoredtotheapplicationratherthangenerically.Whileactivenetworksareaverypowerfulparadigm,thereareseveraldrawbacksthathavehinderedtheiracceptanceandwidespreaddeployment.Theprimaryconcerniswithsecurityandprotectionagainstactiveroutersrunningmali-ciouscodehiddeninactivepackets.Approachesthatlimittheallowableoperationstoasafesubsetlimitthepowerofspecializedhandlingthatispossible.Anequallyimportantissueisthatnetworkoperatorsprefertohavecompletecon-trolovertheirnetworkandallowinguserde nedcodetobedownloadedandexecutedthatcouldpotentiallymakerout-ingdecisionsfordatastreamsisnotveryamenableforac-ceptance.Manyapproachesutilizedcustomizedplatformsandlanguagesraisinginteroperabilityconcerns.Also,thestateofthetechnologyinnetworkprocessorsatthattimepresentedchallengesforthetruerealizationofthisap-proach.Withourframework,weareworkingtowardsthesamegoalofmakingnetworkssmarterbutdoingsowithacompletelydifferentapproachthanactivenetworks.Ourframeworkallowsforthespeci cationof“whattypeofdata”is owingthroughthenetworkratherthanspecifying“howthatdatashouldbehandled”.Essentially,ourframe-workprovidesthehintstothenetworkfabricthroughcon-tentmetadatabuttheactualdecisionofhowbesttohandle2
2RelatedWork
2.1ActiveNetworks
ActiveNetworksisoneoftherevolutionaryapproachestoinjectintelligenceintothenetwork.Atanextremecase,thiscanbeviewedasanefforttoaugmentdatapacketswithcodefragmentscontainingspecializedprocessinglogicforhandlingthatpacket.“Active”routersexecutethecodecar-riedinthepacketallowinghighlycustomizedhandlingof owsorpackets.Thisarchitecturepermitsmassiveincreaseinthecomputationperformedwithinanetworkallowingforthedeploymentofnewservicesintothenetworkinatotallyseemlessandon-demandmanner.Severalprojectshavetakenthisapproachtoimpartingintelligenceintothenet-work.TheSmartPackets[29]approachutilizesaspecial-izedprogramminglanguagecalledSprocketandanassoci-
Today’s model of networking primarily concentrates intelligence at the end hosts with the network itself offering a simple“best-effort”,“data agnostic ” communication medium. However, this paradigm has proven to be insufficient to meet todays needs co
thattypeofstreamislefttotherouterandthenetworkop-erators.Also,theuseofastandardmechanismtodescribemetadataprovidesaviablesolutiontotheinteroperabilityconcerns.Thepolicymechanismusedinourframeworkal-lowsthenetworkoperatortospecifyhandlersthatcanbetriggeredbasedonreasoningoverthecontentmetadatatoinvokespecializedhandling,wherethehandlersareessen-tiallyvalueaddedservicesofferedbythenetworkproviderthemselvesandthereby,trusted.
2.2ContentAdaptation
Contentadaptationisacommonlyusedparadigmtoad-dressissuessuchasef cienttransferofbandwidthinten-sivedataoverabandwidthlimitednetwork,makingthecontentamenabletodeviceswithdiverse/limitedcapabil-ities,personalization,policy-basedadaptations,securityre-latedadaptationsetc.TheOpenPluggableEdgeServices(OPES)[7]isanIETFworkinggrouptaskedwithde n-ingacommonarchitectureforenablingedgebasedcontentadaptation.Theideaistospecifyaplatformprovidingnet-workedservicesattheapplicationlevelforoffloadingori-ginserversandimprovinguserexperience.OPESisgen-erallyapplicableforoperatingonrequestorresponsefordatausingHTTP/SMTP/RTSPwithrulesspeci edinIn-termediaryRuleMarkupLanguage(IRML)[8]todeterminewhatserviceshouldbeusedonwhattypeofcontent.Con-tentadaptationhasalsobeenstudiedextensivelythroughproxybasedsystems.[14]presentsanapplicationlevelcontentadaptationformultimediadataasanef cientso-lutionforhandlingdisseminationofrichcontenttoawidevarietyofdevicesconnectedoverlinkswithdiversechar-acteristics.[16,18]arguesthatwiththediversityofenduserdevices,on-the- yadaptationbytranslationalproxiesattheapplicationlevelisbothanecessaryandacosteffec-tive, exiblesolution.Adaptationofcontenthereisthroughdata-typespeci clossycompressionanddistillation.TheConductor[35]frameworkisasimilarapproachthatcandy-namicallydeploymultipleadapterstooperatealonganap-plication’scommunicationpath.Aplanningalgorithmisbuilt-intodeterminewhatadapterstouseandwhere.