Stochastic Model for QoS Assessment in Multi-tier Web Services

R.M. Czekster, P. Fernandes, A. Sales, T. Webber, A.F. Zorzo

    Research output: Contribution to journalArticlepeer-review


    Service Level Agreements (SLAs) are used to guarantee quality of service (QoS) between customers and service providers. In an SLA, parties establish a common set of rules and responsibilities. In this paper we propose a practical stochastic modeling of a multi-tier architecture considering SLAs for specific transactions. The model is parameterized with available performance testing data for a real web service, and with a testing environment having unpredictable and unknown external workloads of simultaneous execution. In addition, we present multiple scenarios of external applications impacting on the SLAs in our target architecture. Having a previous knowledge about the average time demanded by some external applications, our model results can provide evidences when the system under test will not respect the agreed-upon SLAs. Finally, we discuss possible model extensions towards further unknown workload characterizations and considerations about application execution profiling.
    Original languageEnglish
    Pages (from-to)53-72
    JournalElectronic Notes in Theoretical Computer Science
    Publication statusPublished - 27 Sept 2011

    Bibliographical note

    © 2011 Elsevier B.V. Open access under CC BY-NC-ND license.


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