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

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