András Horváth, Antonio Puliafito, Marco Scarpa, Miklós Telek
Performance and dependability evaluation is a fundamental process in system design and validation. Sophisticated and always more powerful modeling techniques are regularly adopted in order to provide a quantitative and qualitative analysis of systems under examination. Among the others, stochastic Petri nets are a world-wide known technique for modeling computer and communication systems, which was proven to be very flexible and effective. In order to extend their applicability to more complex situations, in this paper we present a new approach for the analysis of non-Markovian Stochastic Petri Net (NMSPN) models, which is based on a discrete time approximation of the stochastic behaviour of the marking process. The proposed approach, which resulted in a new modeling tool for the analysis of NMSPNs called WebSPN, allows to analyze a wider class of PN models with prd, prs and pri concurrently enabled generally distributed transitions. This implies the possibility of dealing with very complex systems with arbitrarily distributed events with very complex interrelations among each other. The adopted technique is described, an application example is solved and the results are carefully analized in order to demonstrate the validity of the proposed approach.