Simulation based validation of quantitative requirements in Service Oriented Architectures

Large Service Oriented Architectures (SOAs) have to fulfill qualitative and quantitative requirements. Usually Service Level Agreements (SLAs) are defined to fix the maximal load the system can accept and the minimal performance and dependability requirements the system has to provide. In a complex SOA where services use other services and thus performance and dependability of a service depend on the performance and dependability of lower level services, it is hard to give reasonable bounds for quantitative measures without performing experiments with the whole system. Since field experiments are too costly, model based analysis, often using simulation is a reliable alternative. The paper presents an approach to model complex SOAs and the corresponding SLAs hierarchically, map the model on a simulator and analyze the model to validate or disprove the different SLAs.