Modeling computer systems evolutions: non-stationary processes and stochastic Petri nets-application to dependability growth

Stochastic Petri nets (SPNs) have emerged over the years as a favored approach for performance and dependability modeling and evaluation. Their usual utilization assumes that systems specification and design do not evolve, in opposition to real-life. This paper is aimed at a preliminary exploration of how to take advantage of the existing body of results on SPNs for modeling the evolution of computer systems, i.e. to model non-stationary stochastic processes. It focuses on dependability evolutions which result from successive releases.