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Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
Parameter Dependencies for Component Reliability Specifications
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Parameter Dependencies for Component Reliability Specifications

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Predicting the reliability of a software system at an architectural level during early design stages can help to make systems more dependable and avoid costs for using the implementation. Existing …

Predicting the reliability of a software system at an architectural level during early design stages can help to make systems more dependable and avoid costs for using the implementation. Existing reliability prediction methods for component-based systems use Markov models and assume that the software architect can provide the transition probabilities between individual components. This is however not possible if the components are black boxes, only at the design stage, or not available for testing. We propose a new modelling formalism that includes parameter dependencies into software component reliability speci fications.
It allows the software architect to only model a system-level usage pro le (i.e., parameter values and call frequencies), which a tool then propagates to individual components to determine the transition probabilities
of the Markov model. We demonstrate the applicability of our approach by modelling the reliability of a retail management system and conduct reliability predictions.

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  • Quality in the sense ofperformance, maintainability, reliability in this talk: focus on reliability
  • Differentlifecyclestages: design, testingTesting: SRGM, curve-fitting on reportedfailures, extrapolation, morethan 40 modelsknownDesign: Goal: determiningsoftwarereliabilitywhenpluggingtogethercomponents
  • About 20 approachesknownwhichfollowthiscycleGoal: Validateuserrequirements, improvearchitecture design, selectfittingcomponentsTheperceivedreliabilitydepends on howthecomponentsareused: iftheunreliablefunctionsarecalledonlyseldomly, theoverallreliabilitymight still behighFailureprobabilitiesmightbedetermined via testing individual componentsbythedevelopersAfter computingtheexpectedreliability- reliabilitycanbecomputedforcertaincomponents- find componentsmostlycontributingtooverallreliability- introduceredundancy
  • TransitionprobabiltiesbetweenthecomponentarisefromtheusageprofileofthesystemDepending on someuseractions, thecomponentmightpropagatecallsdirectedtothemitis vital tohaveaccuratetransitionprobabilitiesotherwisethepredictionbecomeinaccuratetheproblemisespeciallypronunced in a systemcomposed out ofblack box compoents, whichonlydescribetheprovidedandrequiredinterfaces. Whichprovidedservicecallswhichrequiredservice? The dependencyisunknown. Itmightbethecasethat a providedservicedoes not userequiredservicesat all. Itmightbethecasethat a providedserviceusesmanyrequiredservices. Thisis not visiblefromtheinterfacedescriptionbythecomponentdevelopers
  • Onlyfourrepresentativeapproaches- cheungrequiresthewholesystemtobesetupandmeasured, thisis not desirable- hamletisdifficult- reussnerandcheung do not deal withtheissueandassumetheprobabilitiesasgivenorignorethembecausetheyfocus on a singlecomponent.
  • Correct y>5!Useannotationsforloop? Multiple internalactions?Correctfailureprobabilitiesfor P2 and P3
  • a retail chain to handle its sales and manage its inventory dataservice-orientedsystemwithcustomerandproviderfocus on theservicebookSale() oftheInventorycomponent- retail solution clients invoke this operation at the end of each salesprocess in order to update the stock information
  • If we set a goal of 99.99% for the bookSale() reliability, the gure shows thatthis goal is reached with a stock update failure probability of 10-e6 and at most 98items. If the failure probability rises to 2-e6 the goal is only reached with anumber of items smaller than 50.
  • Transcript

    • 1. Parameter Dependencies for Component Reliability Specifications
      HeikoKoziolek (ABB Corporate Research)Franz Brosch (FZI Karlsruhe, Germany)
    • 2. Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      1
      EU Project Q-ImPrESS
      Quality
      Impact
      Prediction for Evolving
      Service-oriented Software
      www.q-impress.eu
    • 3. Software Reliability
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      2
      [Musa1987]
    • 4. Architecture-basedReliability Analysis
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      3
      Markov Model
      ComponentArchitecture
      R = 0.9223
      ExpectedReliability
      Markov Model Solution
      [Trivedi2001]
    • 5. Problem
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      4
      Howtodeterminethetransitionprobabilities?
    • 6. Literature: Existing Approaches
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      5
    • 7. Our Solution
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      6
    • 8. Our Solution: Model
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      7
      Internal Action
      BranchProbability
      Sequence
      Branch
      External Call
    • 9. Our Solution: Model
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      8
      FailureProbability
      BranchProbability
      ExternalCall Inputs
      Parameter Dependency
      Parameter Dependency
      Input Parameter
      Input Parameter
    • 10. Our Solution: Model
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      9
      Loop
      NumberofIterations
    • 11. Our Solution: Model
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      10
    • 12. Our Solution: Transformation
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      11
    • 13. Our Solution: Markov Model Solution
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      12
      R
      Q
      [Trivedi2001]
    • 14. Case Study: Retail Management System
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      13
    • 15. Case Study: Inventory Service - BookSale
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      14
    • 16. Case Study: Modelling
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      15
      Parameter Dependency on Loop Count
      ComponentArchitecture
      PalladioTool
      Control Flow Graph for a Component Service
    • 17. Case Study: Analysis
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      16
      PalladioTool
      Markov Model Solution
    • 18. Case Study: ReliabilityPredictionResults
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      17
    • 19. Case Study: ReliabilityPredictionResults
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      18
    • 20. Assumptions & Limitations
      Markov Property
      FailureProbabilities
      Determiniation?
      Stochastically Independent
      Constant
      Expressiveness
      No Hardware Failures
      NoConcurrency
      NoRepair
      Getting Parameter Dependencies
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      19
    • 21. Conclusion
      Parameter DependenciesforComponentReliabilitySpecifications
      Modellingbycomponentdeveloperandsoftwarearchitect
      Easy alternationofsystem-levelusageprofile
      Reusablereliabilityspecifications
      Heiko Koziolek: Parameter Dependencies for Component Reliability Specifications
      20
      www.q-impress.eu

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