网络中的数据管理的挑战外文翻译.docx

网络中的数据管理的挑战外文翻译.docx

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网络中的数据管理的挑战外文翻译

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系别物联网技术学院

专业物联网应用技术

班级物联网

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ChallengesforDatabaseManagementintheInternetofThings

ThisarticlediscussesthechallengesforDatabaseManagementintheInternetofThings.WeprovidescenariostoillustratethenewworldthatwillbeproducedbytheInternetofThings,wherephysicalobjectsarefullyintegratedintotheinformationhighway.WediscussthedifferenttypesofdatathatwillbepartoftheInternetofThings.Theseincludeidentification,positional,environmental,historical,anddescriptivedata.Weconsiderthechallengesbroughtbytheneedtomanagevastquantitiesofdataacrossheterogeneoussystems.Inparticular,weconsidertheareasofquerying,indexing,processmodeling,transactionhandling,andintegrationofheterogeneoussystems.Werefertotheearlierworkthatmightprovidesolutionsforthesechallenges.FinallywediscussaroadmapfortheInternetofThingsandrespectivetechnicalpriorities.

TheInternetofThings（IoT）isaself-styledtermtodescribeobjectsthatareabletocommunicateviatheInternet.Objectsrangefromsensorinputstoactua-torsthatcontrolphysicalobjectswithnewinteractionsrequiringadvancesinmachineandhumaninterfaces.ItiswidelyforecastthattheseobjectswillnumberinthetrillionsoverthenextfiveyearsofInternetdevelopment.Halleretal.haveprovidedthefollowingdefinition.

“Aworldwherephysicalobjectsareseamlesslyintegratedintotheinformationnetwork,andwherethey,thephysicalobjects,canbecomeactiveparticipantsinbusinessprocesses.Servicesareavailabletointeractwiththese‘smartobjects’overtheInternet,querytheirstateandanyinformationassociatedwiththem,takingintoaccountsecurityandprivacyissues.”

Historically,theIoTreferredmainlytoRadio-frequencyidentification（RFID）taggedobjectsthatusedtheInter-nettocommunicate.Itsoriginslieinthemanufacturingarea,forexample,theAuto-idproject.TheCambridgeAuto-idlaboratoryproducedanumberofwhitearticles,journals,andconferencearticlesontheproject.RFIDisnottheonlymeansofconnectiontotheIoT.Wirelesssensornetworkswillprovidecontinuousstreamsofdataonvariousenvironmentalcharacteristics,whichmaybefedintotheIoT.OthermoresophisticatedbridgestotheIoTincludeidentificationofobjectsviasensingdevices,forexample,objectrecognitionviadigitalimaging.Evermorecapabledisplaypersonal.

Takentoitsextreme,anyeverydayobjectmightbecomepartoftheIoTandbemadeintelligent:

eachbookweread,everydeviceinourhomes,ourpets,everyfoodproduct,everyitemofclothing,andevenourselves.Ofcourseonecanimaginegoodandbadscenariosinthisvision.Itmightbeconvenienttoarrivehomeafteraperiodofabsencetoareceptionofourmostcomfortablehomeenvironmentintermsofheating,lighting,anddigitalentertainment.Thisenvironmentissetupandmaintainedeconomicallyandenergy-efficientlythroughsensorsthatcaptureeveryenvironmentaldetail,makingdecisionsbasedontheirinput,knowledgeofcommod-itytarifffactors,andourpreferences.Letusconsideranothercase.Wecannotfindthebookwearereadingsowepressabuttononthescreenembeddedintoourlivingroomwallandinaninstancethelocationofthebookisrevealed.Orevenmorefuturisticallythebookdetectsourarrivalhome,knowswewanttoreadit,andthereforebleepstoindicateitspresence.

TheIoToffersawealthofpossibilities,butperhapsthereisadownside.Ourpossessions,movements,andactivitiesmightbedetectedbyroguereceiversoperatedbypeoplewithintentionstoputsuchinformationtoillegaluse.Evenoverzealouslegitimatedatacollectioncanseemaninva-sionofprivacy.Securitysystemsarenotfail-proof.Wouldwewishsurveillanceagentstoknoweverythingaboutus,forinstanceourreadinghabits,themusicwelistento,thefoodweeat,withwhomweassociate,andwhereweare?

Suchmattersneedtobecarefullyconsidered.

3.1Size,ScaleandIndexing

ThesizeandscaleofthedataintheIoTwillbevast.Datawillneedtobemanagedviaresponsiblelocalownership.Localownerswilldecidewhichdataandservicestomakeavailabletotheglobalnetwork.Thus,theIoTmayoperateonmorethanonelevel:

privateandpublic.Usersmayjoingroupsforaccesstocertainprivatelyowneddataormay,ontheotherhand,accessdatapubliclyavailableoverthepublicInternet.Theremaybediffer-encesinqualityofdatadependingonownershipandlevelofcare.Graduallytrustandreputationsystemswillprovideinformationtousersonthequalityofthedata.Intheglobalspacetherewillbeaneedforacentralauthority,formanagingaddressesandidentifiers,asthereiswiththecurrentInternet.Indexingwillbeamajorchallenge.FindingaparticulariteminaworldwhereallphysicalobjectshaveanIPaddresswillnotbeeasy,unlesswecandevisesuitableindexingmethods.Workinthelibrarycatalogmanagementmightprovidesomepoint-eraonhowtodothis,buttheIoTwillencompassmanydifferenttypesofobjects.Creatingacatalogofeverythingintheworld,readableacrosscountriesandlanguages,isadauntingtask.Someobjectswillbepubliclyaccessible;somewillneedvariouslevelsofaccesscontrol,andsomemaybeprivatetotheowner.AtfirsttheIoTislikelytodevelopthroughlocalsystemsthatcanbeindexedcoher-entlywithinaboundeddomain.Aslocalsystemsmergewithglobalsystems,newindexingmethodswillneedtobedeveloped.Categoriesofthingswillneedtobedefinedtogetherwithsubcategories.Specializedsearchsitesmayprovideaccesstocertaincategories.Forinstance,ifonewantstofindaparticularcarpart,onemaygotoasearchsitethatspecializesinthattypeofproduct,andfromtherebeguidedtoaspecificIPaddress.

3.2QueryLanguages

Currentpopularquerylanguagesindatabasesystemsrelyonstructureddata.StructuredQueryLanguage（SQL）isthemostprominentexample.Overthelastfewyears,however,therehavebeenproposalsforquerylanguagesforsemi-structureddata,whichismoretypicalofthedataheldontheInternetthequantitiesofdataaresovastthatitwouldbeunrealistictoexpectanysortofuniformstructure,exceptperhapsthatoftheloosestvariety,tobeimposedontheIoT.ExtensibleMarkupLanguage（XML）offersameansofrepresentinglessstructuredaswellasstructureddata,togetherwithsomelevelofselfdescription.Itisawell-acceptedtechnologythatsupportsinteroperabilityatatechnicalratherthanasemanticlevel.XQueryhasbeendevelopedbytheWorldWideWebConsortium（W3CXQueryalanguageforqueryingXML,cancombinedocu-ments,webpages,andlinkstorelationaldatabases.

Querylanguagesforsemi-structureddatausuallyadoptanunderlyingunidirectionalgraph.Requiredobjectsarespecifiedbyprovidingapathexpressioninalanguagethatisusuallyquiteintuitive.Thereare,however,inherentproblemswithhierarchicaldatamodels,suchas,difficultyinrepresentingmany-to-manyrelationships.Inspiteofthis,thehierarchi-caldatamodelhasbeenembracedbythewebcommunityasauseful,intuitive,andpracticalstructure.TheIoTwillhavebrieflyvisitasitetopickupsomedataorinformation,expertusersthatknowexactlywhatdatatheyneedandwheretofindit,andusersthatliesomewhereinbetween.Infactindifferentcontextsthesamepersoncanbeanyoneofthesedifferenttypesofusers.Itthereforeseemsnecessarythatdifferenttypesofdataaccessfacilitiesbeavailable.CasualuserswillneedtoaccesstheIoTviaauser-friendlygraphicaluserinterface（GUI）,withdetailedexplanationavailableonanyobject,andmoreflexible,powerful,andefficientaccessinterfaceswillbeneededforexpertusers.Servicescanbeusedtoprovidebothtypesofaccess.Workinquerylanguagesforsemi-structureddatawillberelevantforthesedevelopments.

3.3ProcessModelingandTransactionsItislikelythatmostprocesseswillbedevelopedandsuppliedasservicesontheIoT.ServiceOrientedArchitects-ture（SOA）isbecominganimportantmeansofsupportinginteroperabilityinweb-basedsystems.Thecentralideaisthatindependentoutfitsofferservicesinauniformmanner,whichotheruserscanthentakeup.Thusimple-mentationdetailsarehiddenfromtheusersoftheservices.Applicationprocesseswilltypicallybemadeupofanum-beroflowerleveltransactions.Transactionsinturnwillbemadeupoflowerleveloperationsorservices.Therefore,thequestionoftransactionprocessingintheIoTarises.InthetraditionaldatabasesystemsthematterofconcurrenttransactionprocessinghasbeenhandledthroughthemaintenanceofACIDpropertiesthroughtimestamping,locking,andatwo-phasecommit.ACIDpropertiesareatomicity,consistency,isolation,anddura-ability.Atransactionmustcompleteinitsentiretyornotatall,atransactionmustleavethedatabaseinaconsistentstate,transactionsshouldnotshowothertransactions,andintermediateresultsandchangesmadebyatransac-tionmustbepermanent.Indistributeddatabasesystemsatwo-phasecommitisusedtopreserveconsistency.Allparticipatingsitesmustconfirmtheirreadinesstocommitbeforethecommitcommandisissuedbythecoordinatingsiteandwrittentothedatabaselog.IthasbeenrecognizedthattheACIDpropertiesdonotfitwebtransactionprocessingwell.Thisisbecausetheindividualwebservicesareessentiallyautonomousandmustindependentlypreserveconsistency.Thisrequire-meantmightconflictwithaconsistencyrequirementofauser’sglobaltransaction.Forinstanceauserseesbookingaholidayasatransactionconsistingof