Visualisation for Stochastic Process Algebras: The Graphic Truth

Abstract

Abstract. There have historically been two approaches to performance modelling. On the one hand, textual language-based formalisms such as stochastic process algebras provide portable and scalable solutions to compositional modelling. On the other hand, graphical formalisms such as stochastic Petri nets and stochastic activity networks provide an automaton-based view of the model, which may be easier to visualise, at the expense of portability. In this paper, we argue that we can achieve the benefits of both approaches by generating a graphical view of a stochastic process algebra model, which is synchronised with the textual representation, giving the user has two ways in which they can interact with the model. We present a tool, as part of the PEPA Eclipse Plug-in, that allows the components of models in the Performance Evaluation Process Algebra (PEPA) to be visualised in a graphical way. This also provides a natural interface for labelling states in the model, which integrates with our interface for specifying and model checking properties in the Continuous Stochastic Logic (CSL). We describe recent improvements to the tool in terms of usability and exploiting the visualisation framework, and discuss some of the general features of the implementation that could be used by other tools. We illustrate the tool using an example based on a model of a financial web-service application.

Invited Response to Computer Journal Lecture by Prof. Jane Hillston

“…This formality also means that the process algebra model can itself be manipulated into provably equivalent alternative forms that are more readily solved by numerical analysis. In the case of PEPA, the specification and analysis is also supported by a powerful set of modelling tools [2,3,4,5,6].…”