分布式计算chp1-introtodistcomp

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1、DistributedcomputingMei-LingLiuDistributedComputing2008-10-9Introduction,M.Liu1Distributedsystem,distributedcomputing¢Earlycomputingwasperformedonasingleprocessor.Uni-processorcomputingcanbecalledcentralizedcomputing.¢Adistributedsystemisacollectionofindependentcomputers,interconnectedviaanetwo

2、rk,capableofcollaboratingonatask.¢Distributedcomputingiscomputingperformedinadistributedsystem.DistributedComputingIntroduction,2008-10-92M.LiuDistributedSystemsworkstationsalocalnetworkTheInternetanetworkhostDistributedComputingIntroduction,2008-10-93M.LiuExamplesofDistributedsystems¢Networkof

3、workstations(NOW):agroupofnetworkedpersonalworkstationsconnectedtooneormoreservermachines.¢TheInternet¢Anintranet:anetworkofcomputersandworkstationswithinanorganization,segregatedfromtheInternetviaaprotectivedevice(afirewall).DistributedComputingIntroduction,2008-10-94M.LiuExampleofalarge-scale

4、distributedsystem–eBay(Source:LosAngelesTimes.)DistributedComputingIntroduction,2008-10-95M.LiuAnexamplesmall-scaledistributedsystem(Source:LosAngelesTimes.)DistributedComputingIntroduction,2008-10-96M.LiuAsmallstate-of-thepracticeDSwirelessto/fromlaptopscablerouter/cablemodemfirewallheadendwir

5、elessaccessEthernetpointDistributedComputingIntroduction,2008-10-97M.LiuComputersinaDistributedSystem¢Workstations:computersusedbyend-userstoperformcomputing¢Servermachines:computerswhichprovideresourcesandservices¢PersonalAssistanceDevices:handheldcomputersconnectedtothesystemviaawirelesscommu

6、nicationlink.DistributedComputingIntroduction,2008-10-98M.LiuThepoweroftheInternet(Source:theUsabilityProfessionalAssociation’ssite.)¢60millionAmericanhouseholdsusecomputers.(TheNewYorkTimes,5/28/98)¢Thenumberofcomputerusersintheworkplacehasincreasedfrom600,000in1976to80milliontoday.(SanFrancis

7、coExaminer,3/29/98)¢84%ofInternetuserssaythattheWebisindispensable.Nearlythesamepercentagefinde-mailindispensable.85%usetheInterneteveryday.(GVU,1997)DistributedComputingIntroduction,2008-10-99M.LiuThePoweroftheInternet–2(Source:w