Fault tolerant 4_5

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MinimizeHumanIntervention Fault Tolerant Patterns.Architectural PatternsEVA Community Ji-won Kim(logicarchitect@ieee.com) 2013.8.24

Intent : People make mistakes and are slow; to minimize downtime the system should take care of itself, without human intervention.1Story Line2Human is not a god

Prevent human from going wrong wayHardware and Software is innocentCommunicationDebug?, Dehuman! On ( ? ) Presentation-Abstraction-Control?BackgroundExampleContextProblemSolutionWhats the PAC?StructureDynamicsHow looks like PAC?StructureDynamicsHow can we implementatino PAC?Any others?VariantsKnown UsesConsequencesSee also

2Incomplete Human

(From a study of the US telephone network[Kuh97])Human can do everything

Recognition/ReportFix/ModificationAnalysisDestructionTest/ PlanningOperationHuman's Creation5

NetworkComputingMachineMathSwitchHuman is not a machine

AlwaysIdentical ProceduralSoftware&HardwareBecome Bored, inattentive with routine, monotonous tasks

5So~? Give them all

Self Recovery

Automatic Error-HandleDetection->ProcessingControl decouple Abstraction and presentation

6Whats the Problem?7The risk of Procedural ErrorsIncorrect system from imperfect Humans Requirements

OperatorWhole SystemImplementation &OperationIf its already planned and predictable, make it all automatic

8Fault ObserverMonitoring SystemComponent1Component2Component3

Fault ObserverFault ObserverRecoverySystemOperatorForces : each agents maintain their own state and dataAgents must effectively cooperate to provide the overall task of the applicationThey need a mechanism for exchanging, data messages, and eventsInteractive agents provide their own user interface

8 BenefitFast Response time for Error situationQuickly Recover ErrorsAvoid this

From Book, originally fromiStockphoto.com/Don BayleyPattern RelationHelpful Patterns :An Input and Output Pattern Language [HS00]- Top-level provides the functional core of the systemIncludes those parts of the user interface that cannot be assigned to particular subtasksIntermediate-level PAC agents represent either combinations of or relationships between, lower-level agents may maintain several views of the same data, such as CAD bottom-level PAC agents represent self-contained semantic concepts which users of the system can act, such as spreadsheets and charts.

10Risk?Mis-operationWindows System Recovery