The monitorability of service-level agreements for application-service provision

  • Authors:

  • James Skene;Allan Skene;Jason Crampton;Wolfgang Emmerich

  • Affiliations:

  • University College London, London, UK;Nottingham Clinical Research Limited, Nottingham, UK;Royal Holloway, University of London, Surrey, UK;University College London, London, UK

  • Venue:
  • WOSP '07 Proceedings of the 6th international workshop on Software and performance
  • Year:
  • 2007

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Abstract

Service-Level Agreements (SLAs) mitigate the risks of a service-provision scenario by associating financial penalties with aberrant service behaviour. SLAs are useless if their provisions can be unilaterally ignored by a party without incurring any liability. To avoid this, it is necessary to ensure that each party's conformance to its obligations can be monitored by the other parties. We introduce a technique for analysing systems of SLAs to determine the degree of monitorability possible. We apply this technique to identify the most monitorable system of SLAs including timeliness constraints for a three-role Application-Service Provision (ASP) scenario. The system contains SLAs that are at best mutually monitorable, implying the requirement for reconciliation of monitoring data between the parties, and hence the need to constrain the parties to report honestly while accommodating unavoidable measurement error. We describe the design of a fair constraint on the precision and accuracy of reported measurements, and its approximate monitorability using a statistical hypothesis test.