PRESEnCE: Performance Metrics Models for Cloud SaaS Web Services.

Cloud services are delivered to cloud customers on a pay-per-use model by the Cloud Services Providers (CSPs). CSP is using Service Level Agreements (SLAs) to define the quality of the provided services. Unfortunately, a standard mechanism does not exist to verify and assure that delivered services satisfy the signed SLA agreement. In this context, an automatic framework named PRESENCE was introduced to define a set of Common performance metrics handled by a set of agents within a customized client (called the Auditor) for measuring the behaviour of cloud applications on top of a given CSP. In this paper, one of the components of the PRESENCE framework dedicated to the provision of stochastic models for selected performance metrics is presented. More precisely, 11 generated models are depicted and analysed, out of which 90,91% accurately represent Web Service (WS) performance metrics for four representatives SaaS components used for the validation of the PRESENCE approach.