Planning Databases Service Level Agreements through Stochastic Petri Nets

The Service Oriented Architecture (SOA) has become a pattern for managing business transactions through distributed services, usually supported by third-party providers. In the SOA world, Service Level Agreements (SLA) are used to establish the requirements between customers and providers. Among the clauses agreed in SLA are those related with databases execution time, which have direct relationship with the overall web services performance. However, the high variability, typical of the SOA environments, makes difficult the negotiation of an appropriate SLA that could be guaranteed in practice. Thus, efforts to predict the quality of SOA-based transactions are justified by anticipate possible problems that tend to arise at run-time, disturbing the SLA clauses. In this article we propose a simulation modeling approach, based on stochastic Petri nets, for performance evaluation of databases requests in data-intensive business applications. Through our proposal it is possible to predict the resources consumption and performance degradation of databases, upon the variation of the workload levels, both at design-time and run-time. A case study was conducted in order to illustrate our contributions.