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 stan- dard ones, particularly to allow the execution on Grid platforms of appli- cations with strict QoS requirements, up to Soft Real-Time. SoRTSim has been designed to be quite general and to be easily customized for dierent tools and classes of applications. We describe the SoRTSim architecture and its implementation, high- lighting 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 denition of the various Grid entities and their behaviour; makes simple the evaluation of performance, based on user-dened metrics and statistics. As a case study, we show how SoRTSim can be used to simulate SoRT- Grid, a framework that we previously developed for managing time con- straints on a Service-oriented Grid.