分布式系统设计.01

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1、DistributedSystemsPrinciplesandParadigmsMaartenvanSteenVUAmsterdam,Dept.ComputerScienceRoomR4.20,steen@cs.vu.nlChapter01:IntroductionVersion:October25,2009ContentsChapter01:Introduction02:Architectures03:Processes04:Communication05:Naming06:Synchronization07:Consistency&Replication08:FaultToleran

2、ce09:Security10:DistributedObject-BasedSystems11:DistributedFileSystems12:DistributedWeb-BasedSystems13:DistributedCoordination-BasedSystems2/26Introduction1.1DefinitionDistributedSystem:DefinitionAdistributedsystemisapieceofsoftwarethatensuresthat:acollectionofindependentcomputersappearstoitsusers

3、asasinglecoherentsystemTwoaspects:(1)independentcomputersand(2)singlesystem)middleware.Computer1Computer2Computer3Computer4Appl.AApplicationBAppl.CDistributedsystemlayer(middleware)LocalOS1LocalOS2LocalOS3LocalOS4Network3/26Introduction1.2GoalsGoalsofDistributedSystemsMakingresourcesavailableDist

4、ributiontransparencyOpennessScalability4/26Introduction1.2GoalsDistributionTransparencyTransp.DescriptionAccessHidesdifferencesindatarepresentationandinvocationmechanismsLocationHideswhereanobjectresidesMigrationHidesfromanobjecttheabilityofasystemtochangethatobject’slocationRelocationHidesfromac

5、lienttheabilityofasystemtochangethelocationofanobjecttowhichtheclientisboundReplicationHidesthefactthatanobjectoritsstatemaybereplicatedandthatreplicasresideatdifferentlocationsConcurrencyHidesthecoordinationofactivitiesbetweenobjectstoachieveconsistencyatahigherlevelFailureHidesfailureandpossibl

6、erecoveryofobjectsNoteDistributiontransparencyisaniceagoal,butachievingitisadifferentstory.5/26Introduction1.2GoalsDistributionTransparencyTransp.DescriptionAccessHidesdifferencesindatarepresentationandinvocationmechanismsLocationHideswhereanobjectresidesMigrationHidesfromanobjecttheabilityofasys

7、temtochangethatobject’slocationRelocationHidesfromaclienttheabilityofasystemtochangethelocationofanobjecttowhichtheclientisboundReplicationHidesthefactthatanobjectoritsstatemaybereplicatedandthatreplicasresideatdiffere