SoRTSim: A high-level simulator for the evaluation of QoS models on Grid

We present SoRTSim, a high-level simulator designed to evaluate tools built over the middleware to support additional services besides the standard ones, particularly to allow the execution on Grid platforms of applications with strict QoS requirements, up to Soft Real-Time. SoRTSim has been designed to be quite general and to be easily customized for different tools and classes of applications. We describe the SoRTSim architecture and its implementation, highlighting its main features. The simulator allows the easy generation of a high number of abstract Grid scenarios, starting from a set of constraints; supports the definition of the various Grid entities and their behaviour; and makes simple the evaluation of performance, based on user-defined metrics and statistics. As a case study, we show how SoRTSim can be used to simulate SoRTGrid, a framework that we previously developed for managing time constraints on a Service-oriented Grid.