Visualisation for Stochastic Process Algebras: The Graphic Truth

There have historically been two approaches to performance modelling. On the one hand, textual language-based formalisms such as stochastic process algebras allow compositional modelling that is portable and easy to manage. In contrast, 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.