《物联网专业英语教程》课件第10章

Unit10CloudComputing[177]

TextA

HowCloudComputing

Works？[185]

TextB

4G—TheFutureofMobile

Internet[190]参考译文云计算是如何工作的？

1．Introduction

Let'ssayyou'reanexecutiveatalargecorporation.Yourparticularresponsibilitiesincludemakingsurethatallofyouremployeeshavetherighthardwareandsoftwaretheyneedtodotheirjobs.HowCloudComputingWorks？Buyingcomputersforeveryoneisn'tenough—youalsohavetopurchasesoftwareorsoftwarelicensestogiveemployeesthetoolstheyrequire.Wheneveryouhaveanewhire,youhavetobuymoresoftwareormakesureyourcurrentsoftwarelicenseallowsanotheruser.It'ssostressfulthatyoufinditdifficulttogotosleeponyourhugepileofmoneyeverynight.

Soon,theremaybeanalternativeforexecutiveslikeyou.Insteadofinstallingasuiteofsoftwareforeachcomputer,you'donlyhavetoloadoneapplication.ThatapplicationwouldallowworkerstologintoaWeb-basedservicewhichhostsalltheprogramstheuserwouldneedforhisorherjob.RemotemachinesownedbyanothercompanywouldruneverythingfromE-mailtowordprocessingtocomplexdataanalysisprograms.It'scalledcloudcomputing,anditcouldchangetheentirecomputerindustry.

Inacloudcomputingsystem(SeeFigure10.1),there'sasignificantworkloadshift.Localcomputersnolongerhavetodoalltheheavyliftingwhenitcomestorunningapplications.Thenetworkofcomputersthatmakeupthecloudhandlestheminstead.Hardwareandsoftwaredemandsontheuser'ssidedecrease.Theonlythingtheuser'scomputerneedstobeabletorunisthecloudcomputingsystem'sinterfacesoftware,whichcanbeassimpleasaWebbrowser,andthecloud'snetworktakescareoftherest.

There'sagoodchanceyou'vealreadyusedsomeformofcloudcomputing.Ifyouhaveane-mailaccountwithaWeb-basedE-mailservicelikeHotmail,Yahoo!MailorGmail,thenyou'vehadsomeexperiencewithcloudcomputing.InsteadofrunninganE-mailprogramonyourcomputer,youlogintoaWebE-mailaccountremotely.Thesoftwareandstorageforyouraccountdoesn'texistonyourcomputer—it'sontheservice'scomputercloud.

Figure10.1Atypicalcloudcomputingsystem

2．CloudComputingArchitecture

Whentalkingaboutacloudcomputingsystem,it'shelpfultodivideitintotwosections:thefrontendandthebackend.Theyconnecttoeachotherthroughanetwork,usuallytheInternet.Thefrontendisthesidethecomputeruser,orclient,sees.Thebackendisthe"cloud"sectionofthesystem.

Thefrontendincludestheclient'scomputer(orcomputernetwork)andtheapplicationrequiredtoaccessthecloudcomputingsystem.Notallcloudcomputingsystemshavethesameuserinterface.ServiceslikeWeb-basedE-mailprogramsleverageexistingWebbrowserslikeInternetExplorerorFirefox.Othersystemshaveuniqueapplicationsthatprovidenetworkaccesstoclients.

Onthebackendofthesystemarethevariouscomputers,serversanddatastoragesystemsthatcreatethe"cloud"ofcomputingservices.Intheory,acloudcomputingsystemcouldincludepracticallyanycomputerprogramyoucanimagine,fromdataprocessingtovideogames.Usually,eachapplicationwillhaveitsowndedicatedserver.

Acentralserveradministersthesystem,monitoringtrafficandclientdemandstoensureeverythingrunssmoothly.Itfollowsasetofrulescalledprotocolsandusesaspecialkindofsoftwarecalledmiddleware.Middlewareallowsnetworkedcomputerstocommunicatewitheachother.Mostofthetime,serversdon'trunatfullcapacity.Thatmeansthere'sunusedprocessingpowergoingtowaste.It'spossibletofoolaphysicalserverintothinkingit'sactuallymultipleservers,eachrunningwithitsownindependentoperatingsystem.Thetechniqueiscalledservervirtualization.Bymaximizingtheoutputofindividualservers,servervirtualizationreducestheneedformorephysicalmachines.

Ifacloudcomputingcompanyhasalotofclients,there'slikelytobeahighdemandforalotofstoragespace.Somecompaniesrequirehundredsofdigitalstoragedevices.Cloudcomputingsystemsneedatleasttwicethenumberofstoragedevicesitrequirestokeepallitsclients'informationstored.That'sbecausethesedevices,likeallcomputers,occasionallybreakdown.Acloudcomputingsystemmustmakeacopyofallitsclients'informationandstoreitonotherdevices.Thecopiesenablethecentralservertoaccessbackupmachinestoretrievedatathatotherwisewouldbeunreachable.Makingcopiesofdataasabackupiscalledredundancy.

3．CloudComputingApplications

Theapplicationsofcloudcomputingarepracticallylimitless.Withtherightmiddleware,acloudcomputingsystemcouldexecutealltheprogramsanormalcomputercouldrun.Potentially,everythingfromgenericwordprocessingsoftwaretocustomizedcomputerprogramsdesignedforaspecificcompanycouldworkonacloudcomputingsystem.

Whywouldanyonewanttorelyonanothercomputersystemtorunprogramsandstoredata?Herearejustafewreasons:

Clientswouldbeabletoaccesstheirapplicationsanddatafromanywhereatanytime.TheycouldaccessthecloudcomputingsystemusinganycomputerlinkedtotheInternet.Datawouldn'tbeconfinedtoaharddriveononeuser'scomputerorevenacorporation'sinternalnetwork.

Itcouldbringhardwarecostsdown.Cloudcomputingsystemswouldreducetheneedforadvancedhardwareontheclientside.Youwouldn'tneedtobuythefastestcomputerwiththemostmemory,becausethecloudsystemwouldtakecareofthoseneedsforyou.Instead,youcouldbuyaninexpensivecomputerterminal.Theterminalcouldincludeamonitor,inputdeviceslikeakeyboardandmouseandjustenoughprocessingpowertorunthemiddlewarenecessarytoconnecttothecloudsystem.Youwouldn'tneedalargeharddrivebecauseyou'dstoreallyourinformationonaremotecomputer.

Corporationsthatrelyoncomputershavetomakesuretheyhavetherightsoftwareinplacetoachievegoals.Cloudcomputingsystemsgivetheseorganizationscompany-wideaccesstocomputerapplications.Thecompaniesdon'thavetobuyasetofsoftwareorsoftwarelicensesforeveryemployee.Instead,thecompanycouldpayameteredfeetoacloudcomputingcompany.

Serversanddigitalstoragedevicestakeupspace.Somecompaniesrentphysicalspacetostoreserversanddatabasesbecausetheydon'thaveitavailableonsite.Cloudcomputinggivesthesecompaniestheoptionofstoringdataonsomeoneelse'shardware,removingtheneedforphysicalspaceonthefrontend.

CorporationsmightsavemoneyonITsupport.Streamlinedhardwarewould,intheory,havefewerproblemsthananetworkofheterogeneousmachinesandoperatingsystems.

Ifthecloudcomputingsystem'sbackendisagridcomputingsystem,thentheclientcouldtakeadvantageoftheentirenetwork'sprocessingpower.Often,scientistsandresearchersworkwithcalculationssocomplexthatitwouldtakeyearsforindividualcomputerstocompletethem.Onagridcomputingsystem,theclientcouldsendthecalculationtothecloudforprocessing.Thecloudsystemwouldtapintotheprocessingpowerofallavailablecomputersonthebackend,significantlyspeedingupthecalculation.

4．CloudComputingConcerns

Perhapsthebiggestconcernsaboutcloudcomputingaresecurityandprivacy.Theideaofhandingoverimportantdatatoanothercompanyworriessomepeople.Corporateexecutivesmighthesitatetotakeadvantageofacloudcomputingsystembecausetheycan'tkeeptheircompany'sinformationunderlockandkey.

Thecounterargumenttothispositionisthatthecompaniesofferingcloudcomputingservicesliveanddiebytheirreputations.Itbenefitsthesecompaniestohavereliablesecuritymeasuresinplace.Otherwise,theservicewouldloseallitsclients.It'sintheirinteresttoemploythemostadvancedtechniquestoprotecttheirclients'data.

Privacyisanothermatter.Ifaclientcanloginfromanylocationtoaccessdataandapplications,it'spossibletheclient'sprivacycouldbecompromised.Cloudcomputingcompanieswillneedtofindwaystoprotectclientprivacy.Onewayistouseauthenticationtechniquessuchasusernamesandpasswords.Anotheristoemployanauthorizationformat—eachusercanaccessonlythedataandapplicationsrelevanttohisorherjob.

Somequestionsregardingcloudcomputingaremorephilosophical.Doestheuserorcompanysubscribingtothecloudcomputingserviceownthedata?Doesthecloudcomputingsystem,whichprovidestheactualstoragespace,ownit?Isitpossibleforacloudcomputingcompanytodenyaclientaccesstothatclient'sdata?Severalcompanies,lawfirmsanduniversitiesaredebatingtheseandotherquestionsaboutthenatureofcloudcomputing.

1.Howfastis4G?

1.1WhatDoes4GMeantoYou?

4Gsimplymeansfourthgenerationinmobiletechnologies.ItisthecommonnameforIMT

(InternationalMobileTelecommunications)AdvancedstandardsdefinedbyInternational4G—TheFutureofMobileInternet

TelecommunicationsUnion(ITU).Whatdoesthestandardmeantocommonman?ItmeansanawesomeoneGigabitpersecondofdownloadspeed,whileyouaccesstheinternet,throughwirelessmeans!Whenboththetransmittingandreceivingstationaremobile,thespeedisabitless.Whenmobile,thatisataspeedofatleast60Mph,4Goffersyouadownloadspeedof100Megabitspersecond.Morebluntly,4GallowsyoutodownloadanHDmovieinnomorethan30seconds!ITU-RadiocommunicationsdefinesIMT-Advanced(4G)asanetworkwhichprovidesaglobalplatformonwhichtobuildthenextgenerationsofmobileservices—fastdataaccess,unifiedmessagingandbroadbandmultimedia—intheformofexcitingnewinteractiveservices.

1.2TheFourthGenerationofMobileTechnologes

Nowmorepertinentquestions,therearealotoftechnologiesofferinghighspeedinternet,howwouldoneknowifhe/sheisusingthis4Gstuffornot?Well,ITUhasspecifiedcertaintechnicalstandards,whichshouldbemetbyanytechnologythatclaimstobe4G.Thespecificationslisttheminimumdatatransferratethattheproposed4Gnetworkshouldhave.The4Gworkinggrouphasdefinedthefollowingasobjectivesofthe4Gwirelesscommunicationstandard:

·Anominaldatarateof100Mbit/swhiletheclientphysicallymovesathighspeedsrelativetothestation,and1Gbit/swhileclientandstationareinrelativelyfixedpositionsasdefinedbytheITU-R.

·Adatarateofatleast100Mbit/sbetweenanytwopointsintheworld.

·Flexiblechannelbandwidth,between5and20MHz,optionallyupto40MHz.

·Peaklinkspectralefficiencyof15bit/s/Hzinthedownlink,and6.75bit/s/Hzintheuplink(meaningthat1Gbit/sinthedownlinkshouldbepossibleoverlessthan67MHzbandwidth).

·Systemspectralefficiencyofupto3bit/s/Hz/cellinthedownlinkand2.25bit/s/Hz/cellforindoorusage.

·Highqualityofservicefornextgenerationmultimediasupport(realtimeaudio,highspeeddata,HDTVvideocontent,mobileTV,etc.).

·Interoperabilitywithexistingwirelessstandards,andanallIP,packetswitchednetwork.

·Smoothhand-off,seamlessconnectivityandglobalroamingacrossmultiplenetworks.

2.WhatistheImportanceof4G?

Whatmakes4G,orforthatmatterwirelessbroadband,inevitable?Howis4Ggoingtobringchangesineverythingrelatedtointernet?ThelastspecificationmentionedintheITU-Rstandardmakesitmoreattractive:thedatatransferthroughthenetworkisusingpackets,usingIPorinternetprotocol.

TherevolutionbroughtoutbyWeb2.0isquiteconspicuoustobemissed.Usergeneratedcontentliterallyruledtheweb;portalsandsocialnetworkingsiteslikeyoutubeandfacebookbecamenothinglessthanculturalicons.Thewebisstillimproving.InteractiveapplicationslikeIPTVjustchangedourconceptoftelevisionbroadcasting.Allthesearegoingtoradicallyimprove,perhaps,beyondourimagination,onceweswitchoverto4Gnetworks.Themajorchallengetheseapplicationsarefacingisnotthetechnologyofthemselves,butthatofnetworks-informationbottlenecks.Uploadspeedsarestillaconcern,allthemoreifitisamobileplatform.Hereiswhere4Gcomesintoplaywithitsamazingonegigabitperseconddatarate.Theultra-fast4Gcouldtrulyrevolutionizeourconceptofinteractiveapplications.

3．TheFutureof4GandYou

Cloudcomputingisanotherarea,whichisgoingtoreallycashonswitchingoverto4Gnetworks.Increasedspeed,mobilityandportabilitythat4Goffers,isashotinthearmforcloudcomputingapplications.Whenpeopleavoidcapitalexpenditureonresources,theincreaseddatatransferratewillbeamustforapplicationstoworksmoothly.Ifyouaresavingyourdataonaserverorrunningyourfavoriteapplicationfromtheserver,(becauseyoudonotwantaharddiskcarriedwithyou)howmuchtimecanyouaffordtogetthedatadown?Evencoupleofsecondswouldmakethecloudcomputingunattractive.Cloudcomputingthusenablesmobilephonesizedstationstobeactedaspowerfulcomputers,ifandonlyiftheyareconnectedtosomethingthatoffersa4Gspeedinuploadaswellasdownload.Themobilityofferedmakesthewholethingpersonalandportable,allthewhilebeingcosteffective.Imagine,usingthewholeoperatingsystemitselfthroughthecloudcomputingarchitecture.4Gmakesthisabsolutelypossible!

InternetofThings(IoT)isthenextbigthingtohappen.Itisdubbedasthefutureinwhichphysicalobjects,eveninoureverydaylife,aregoingtogetnetworked.ItissomethingsimilartothepresentdayRFIDcardsandothertypesofidentificationtechnologies.Thedaywillnotbefarwhenourpen,book,shirts,shoesorpartsofautomobilesareequippedwithminusculeidentifyingchipswhichexchangesinformationbetweenthem.Imaginetheflowofinformation.Itcandoubtlesslybesaid4Gwillbeasignificantsteptowardssuchaninternetofthings.

4．How4Gcanchangeyourlife?

NationalbroadbandplanoftheUnitedStatesFederalCommunicationsCommissionenvisionshowaparadigmaticshiftcanbebroughtaboutinanumberofareaslikehealthcare,education,economicopportunities,energyandenvironment,governmentperformance,civicengagementandpublicsafetybyadoptingbroadband.Marketswillbegivennewopportunitiesandconsumerscanavailnewproducts.Using4G,classroomexperiencecanbedramaticallyaltered.Bothinsideoutandoutsideclassrooms,learningcanbemorefunandinteractive.Interactiveapplicationsandfasterknowledgesharingwillmakehealthcarecost-effectiveandtime-saving.Modernizationofelectricgridwouldmeanmoreenergyconservation.4Gisenvironmentfriendlywhenthetransmissionpowerisutilizedtocarrymoredatathanpreviousgenerationtechnologiespracticallycarried.Theworldismovingtowardse-governance.Betterservicedeliverythrough4Gtechnologyissomethingthatisdesiredacrosstheglobe.Broadbandservicesenablethecitizentoeffectivelyutilizehisrighttoinformationconcerninggovernmentinformation.Anotherimportantfeatureofthe4Gstandardswillbeimprovedsecurityofdata.Duetoitsemphasisonrobustnessandsecurity,theconcernsaboutdatatheftwouldbeminimized.

Insummary,4Gcanbesaidtogivethebestthatawirelessnetworkisdesiredof.Itgivesultrahi-speedinternetwithportability,reliabilityandeasyaccessibility.Whiledownloadanduploadlimitsandspeedreductionscontinuetoworryourdailyroutines,adopting4Gisinevitableaswellasimminent.

1.绪论

假定你是大公司的主管，你负有特殊的责任，包括让全体员工都有适当的硬件和软件来满足其工作要求。但只为每人购买计算机是不够的——还要购买软件或软件许可，为员工提供所需要的工具。只要雇佣新员工，就必须购买更多的软件或确保现有的软件许可供另一个员工使用，以确保软件够用。压力如此之大，以至于你每夜都无法在“钱墩”上入睡。云计算是如何工作的？对于像你这样的主管，不久就会有其他的选择了。你无需为每个计算机安装整套的软件，而是只装入一个应用程序。该应用程序让工作人员登录基于网络的服务，它为用户提供工作所需的全部程序。其他公司的远程机器可以运行各种程序，从电子邮件、文字处理到复杂的数据分析。这种服务叫云计算，它可能会改变整个计算机行业。

在云计算系统中，有一个重要的工作量转移。当运行应用程序时，本地计算机不用再承担全部繁重的任务，而是由构成云的云计算机网络去处理它们，所以用户端所需的软件和硬件会减少。用户的计算机只要能够运行云计算系统的接口软件(可以只是一个网络浏览器)即可，而云网络完成其余任务。

你可能已经使用了某种形式的云计算。如果你有一个基于网络电子邮件服务的电子邮件账号，如Hotmail、Yahoo!Mail或Gmail账号，那么你已经有了一些云计算体验。因为你不是在你的计算机上运行电子邮件程序，而是远程登录网络电子邮件账号。这些软件和你的账号并不存储在你的计算机上—而是存储在提供服务的计算机云中。

2.云计算体系结构

当谈论云计算系统时，将其分为以下两部分是有益的：前端和后端。它们通过网络(通常是因特网)彼此连接。前端是计算机用户这一方，或称客户端；后端是该系统的“云”