Content and context aware networking using semantic tagging(3)

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.

[26]presentsaframeworkforadaptingmultimediawebdocumentstooptimallymatchtheneedsoftherequestingclientdevicesusingamultimodal,multiresolutionrepre-sentationhierarchyforthecontentandaCustomizerthatpicksthebestcontentrepresentationthatprovidesmaxi-mumvaluetotheclient.Inthismodel,thecontentauthorprovidesthetranscodingpoliciesandcontrolstheadapta-tionandthisisdoneinanof inemanner(asopposedtoonrequestinmostproxybasedtranscodingsystems).[31]presentsaContent-awareActiveGateway(CAG)architec-tureallowingforonthe ycontentadaptation.Theyrelyontheabilityto lterspeci ctypesoftraf cbyidentifyingpat-3

ternsintheheaderorpayloadofpackets.Thegeneralideaistorunspecializedprograms(staticallyinstalledordown-loaded)onenterprise/residentialgatewaysthatcanregister lters(portnumber,IPaddressetc)onthepacketroutingfabric.These ltersareactivatedwhenpacketsmatchingthosecriteriaareencounteredandpassedtotheCAGcom-putationlayerforprocessingatclosetolinespeed.[9]isaproxybasedwebcontentadaptationforsupportingbrowsingbymobiledevicesoverwirelesslinksusinguserspeci edpreferences.[32]usesalinklevelredirectionin-frastructurecalledSelNetthattagspacketsatlinklevelwithfunctionidenti erstoenableaproxybasedcontentadapta-tion.[6]proposeaservercentriccontentadaptationframe-workcreatingservicespeci coverlaynetworksthroughtheuseofdynamicproxiesalongthedatapath.[30]pro-poseaclientcentriccontentadaptationusingWebStreamCustomizers(WSC)allowingforsystembasedandcontentbasedcustomization.Inadditiontoresearchprojects,sev-eralcommercialestablishmentshavebeenlaunchedwithcontentadaptationastheirprimarybusinessfocussuchasVoiceAgeNetworks,Volantis,Adamind,LightSurf,Sens-eStream,Mobixelletc.

Oneofthegoalsthatwehaveidenti edforourframeworkistosupportcontentadaptationfordatastreams.Ourap-proachofusingsemantictagsembeddedinthestreamwillallowcontentprovidersto“signal”theiradaptationpoliciesandrequirements.AsdiscussedinSection3,thiscanbebothin-bandorout-of-band.Anintelligentstreamproces-sorcanreasonoverthisinformationandusingitsexistingknowledgebase,theappropriatecontentadaptationservicescanbeapplied.

2.3CrossLayerTechniques

StrictLayeringhasbeentheprimarydesigntechniquefornetworkingstackswhichhasresultedinsimple,scal-ableandinteroperablesolutions.Proponentsofthelay-eredmodelsuchas[21]arguethatcrosslayeroptimiza-tionbreaksthearchitecturalsimplicityoflayeringandistooshortterminvisionandhighlyspeci c(totopology,tech-nology,applicationetc.)leadingtospaghettiimplementa-tionsandwillnotseewidespreaddeployment.Thecounterargumenthasbeenthatrestrictingtheinteractionsbetweenlayerstodataandwellde nedprimitivesimposesaratheruniformhandlingsemanticfordatastreamswhichisnotal-waysthemostef cient.Muchoftheworkoncrosslayeroptimizationshasfocusedonoptimizationsatthenetworkedgesprimarilyforwirelesstechnologies.In[17],inganEligibleRateEstimate,thequal-ityofthevideoisdynamicallyadjustedtooffertheuser,uninterruptedvideoatthebestqualitythatcanbesustained.MobiWeb[25]isaframeworkforsupportingadaptiveap-

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