QoS-Aware Replanning of Composite Web Services

  • Authors:

  • Gerardo Canfora;Massimiliano Di Penta;Raffaele Esposito;Maria Luisa Villani

  • Affiliations:

  • University of Sannio;University of Sannio;University of Sannio;University of Sannio

  • Venue:
  • ICWS '05 Proceedings of the IEEE International Conference on Web Services
  • Year:
  • 2005

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Abstract

Run-time service discovery and late-binding constitute some ofthe most challenging issues of service-oriented software engineering.For late-binding to be effective in the case of composite services,a QoS-aware composition mechanism is needed. This meansdetermining the set of services that, once composed, not only willperform the required functionality, but also will best contribute toachieve the level of QoS promised in Service Level Agreements (SLAs). However, QoS-aware composition relies on estimated QoS values and workflow execution paths previously obtained using a monitoring mechanism. At run-time, the actual QoS valuesmay deviate from the estimations, or the execution path may not bethe one foreseen. These changes could increase the risk of breakingSLAs and obtaining a poor QoS. Such a risk could be avoided byreplanning the service bindings of the workflow slice still to be executed. This paper proposes an approach to trigger and perform compositeservice replanning during execution. An evaluation has been performedsimulating execution and replanning on a set of composite serviceworkflows.