Toward an analytical method for SLA validation

Abstract

Quantitative properties of modern software systems are often defined as a part of a service-level agreement (SLA) that fixes the maximal load to be submitted to a system and guarantees bounds for the response time or delay. The evaluation of software architectures in order to validate SLAs is a challenging task since the systems tend to be complex, highly dynamic and to some extent unpredictable. Thus, there is a need for fast and abstract techniques to evaluate the performance of modern software architectures based on the information available in the SLAs. The paper presents an efficient approach to compute bounds on the delay of composed systems based on available bounds for the load and the response times of components. The technique can be used by a user of a software architecture to validate SLAs of composed services based on SLAs of the components. It can also be used by a provider of a software architecture to validate whether additional users can be accepted or to compute required service capacities to fulfill an SLA.