An Introduction to New Extensions for Stochastic Activity Networks

ABSTRACT Stochastic activity networks (SANs) are a powerful and flexible extension of Petri nets. However, SANs facilities are not enough for modeling and analysis of complex and large-scale systems. In order to provide such high-level modeling facilities, we have defined some new extensions for SANs. We intend to preserve all capabilities of SANs for performance, dependability and performability evaluations in these new extensions. In this paper, we present a brief introduction to these new extensions, including hierarchical stochastic activity networks (HSANs) , colored stochastic activity networks (CSANs) , and object stochastic activity networks (OSANs) . Some properties and applications of these models and their analysis methods will also be discussed. KEY WORDS: Modeling, High-Level Petri Nets, Stochastic Activity Networks, Object-Oriented Modeling. 1. INTRODUCTION Petri nets (PNs) have been introduced in 1962 for modeling concurrent and distributed systems [1]. In addition to formal definition and structures, PNs have graphical representation, which helps them to be understood easily. Having only two primitives (i.e.