Experiences with the PEPA performance modelling tools

Abstract

The PEPA language [1] is supported by a suite of modelling tools which assist in the solution and analysis of PEPA models. The design and development of these tools have been influenced by a variety of factors, including the wishes of other users of the tools to use the language for purposes which were not anticipated by the tool designers. In consequence, the suite of PEPA tools has adapted to attempt to serve the needs of these users while continuing to support the language designers themselves. In this paper we report on our use of the PEPA tools and give some advice gained from our experiences.

Performability of a Secure Electronic Voting Algorithm

“…Evaluating this model using the PEPA Workbench [4] the number of states for a two voter system is found to be 561, for 3 voters 8583 and for 4 voters 130245 states. Four voters was the largest system it was possible to analyse directly using the PEPA Workbench before running out of memory.…”

Exploiting Modal Logic to Express Performance Measures

“…However, the extraction of performance measures from the resulting steady state probability distribution has been a largely ad hoc procedure. A reward structure is used to calculate appropriate expectations over the state space but determining which states should have a reward attached has relied on the knowledge of the modeller, and such states were characterised as syntactic terms [17]. Apart from relying on the modeller's insight, this technique also has the disadvantage of being incompatible with the automatic aggregation.…”

Visual representation of stochastic process algebra models

“…simplicity and solvability, are varied. Because stochastic process algebra, such as PEPA [1], are formally defined and have formal notions of equivalence it is possible to define transformations which automatically translate one specification to one or more others in a provably correct manner. However, the majority of the motivations for performing such transformations and some of the notions of equivalence used relate more to the state space of the solution than the behaviour of the model as related to the design.…”