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The PEPA Workbench: A Tool to Support a Process Algebrabased Approach to Performance Modelling
 In Proceedings of the Seventh International Conference on Modelling Techniques and Tools for Computer Performance Evaluation, number 794 in Lecture Notes in Computer Science
, 1994
"... . In this paper we present a new technique for performance modelling and a tool supporting this approach. Performance Evaluation Process Algebra (PEPA) [1] is an algebraic language which can beused to build models of computer systems which capture information about the performance of the system. The ..."
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Cited by 176 (62 self)
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. In this paper we present a new technique for performance modelling and a tool supporting this approach. Performance Evaluation Process Algebra (PEPA) [1] is an algebraic language which can beused to build models of computer systems which capture information about the performance of the system. The PEPA language serves two purposes as a formal description language for computer system models. The performancerelated information in the model may be used to predict the performance of the system whereas the behavioural information in the model may be exploited when reasoning about the functional behaviour of the system (e.g. when finding deadlocks or when exhibiting equivalences between subcomponents). In this paper we concentrate on the performance aspects of the language. A method of reasoningaboutPEPA modelsproceedsby considering the derivation graph obtained from the model using the underlying operational semantics of the PEPA language. The derivation graph is systematically reduced ...
A brief history of process algebra
 Theor. Comput. Sci
, 2004
"... Abstract. This note addresses the history of process algebra as an area of research in concurrency theory, the theory of parallel and distributed systems in computer science. Origins are traced back to the early seventies of the twentieth century, and developments since that time are sketched. The a ..."
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Cited by 82 (1 self)
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Abstract. This note addresses the history of process algebra as an area of research in concurrency theory, the theory of parallel and distributed systems in computer science. Origins are traced back to the early seventies of the twentieth century, and developments since that time are sketched. The author gives his personal views on these matters. He also considers the present situation, and states some challenges for the future.
Process Algebra for Performance Evaluation
, 2000
"... This paper surveys the theoretical developments in the field of stochastic process algebras, process algebras where action occurrences may be subject to a delay that is determined by a random variable. A huge class of resourcesharing systems  like largescale computers, clientserver architectur ..."
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Cited by 72 (13 self)
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This paper surveys the theoretical developments in the field of stochastic process algebras, process algebras where action occurrences may be subject to a delay that is determined by a random variable. A huge class of resourcesharing systems  like largescale computers, clientserver architectures, networks  can accurately be described using such stochastic specification formalisms.
Implementation of Symbolic Model Checking for Probabilistic Systems
, 2002
"... In this thesis, we present ecient implementation techniques for probabilistic model checking, a method which can be used to analyse probabilistic systems such as randomised distributed algorithms, faulttolerant processes and communication networks. A probabilistic model checker inputs a probabilist ..."
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Cited by 70 (21 self)
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In this thesis, we present ecient implementation techniques for probabilistic model checking, a method which can be used to analyse probabilistic systems such as randomised distributed algorithms, faulttolerant processes and communication networks. A probabilistic model checker inputs a probabilistic model and a speci cation, such as \the message will be delivered with probability 1", \the probability of shutdown occurring is at most 0.02" or \the probability of a leader being elected within 5 rounds is at least 0.98", and can automatically verify if the speci cation is true in the model.
An Efficient Algorithm for Aggregating PEPA Models
 IEEE Transactions on Software Engineering
, 1999
"... Performance Evaluation Process Algebra (PEPA) is a formal language for performance modelling based on process algebra. It has previously been shown that using the process algebra apparatus compact performance models can be derived which retain the essential behavioural characteristics of the modelle ..."
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Cited by 62 (30 self)
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Performance Evaluation Process Algebra (PEPA) is a formal language for performance modelling based on process algebra. It has previously been shown that using the process algebra apparatus compact performance models can be derived which retain the essential behavioural characteristics of the modelled system. However no efficient algorithm for this derivation was given. In this paper we present an efficient algorithm which recognises and takes advantage of symmetries within the model and avoids unnecessary computation. The algorithm is illustrated by a multiprocessor example. Keywords: Performance modelling, model aggregation, performance evaluation tools, stochastic process algebras. 1 Introduction In recent years several Markovian process algebras (MPAs) have been presented in the literature. These include PEPA [1], MTIPP [2], and EMPA [3]. As with classical process algebras, these formalisms allow models of systems to be constructed which are amenable to functional or behavioural an...
How to Specify and Verify the LongRun Average Behavior of Probabilistic Systems
 In Proc. LICS'98
, 1998
"... Longrun average properties of probabilistic systems refer to the average behavior of the system, measured over a period of time whose length diverges to infinity. These properties include many relevant performance and reliability indices, such as system throughput, average response time, and mean t ..."
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Cited by 61 (3 self)
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Longrun average properties of probabilistic systems refer to the average behavior of the system, measured over a period of time whose length diverges to infinity. These properties include many relevant performance and reliability indices, such as system throughput, average response time, and mean time between failures. In this paper, we argue that current formal specification methods cannot be used to specify longrun average properties of probabilistic systems. To enable the specification of these properties, we propose an approach based on the concept of experiments. Experiments are labeled graphs that can be used to describe behavior patterns of interest, such as the request for a resource followed by either a grant or a rejection. Experiments are meant to be performed infinitely often, and it is possible to specify their longrun average outcome or duration. We propose simple extensions of temporal logics based on experiments, and we present modelchecking algorithms for the verif...
Markovian Process Algebra: Composition and Equivalence
, 1994
"... Markovian Process Algebra (MPA) is a process algebra enhanced with exponential timing which allows the mapping of specifications on continuous time Markov chains (CTMCs). This paper introduces a compositional approach to compute the generator matrix of the CTMC underlying a MPA specification which c ..."
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Cited by 59 (5 self)
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Markovian Process Algebra (MPA) is a process algebra enhanced with exponential timing which allows the mapping of specifications on continuous time Markov chains (CTMCs). This paper introduces a compositional approach to compute the generator matrix of the CTMC underlying a MPA specification which consists of the parallel composition of finite state agents. Furthermore two different equivalence relations covering quantitative and qualitative aspects are introduced. These equivalence relations are shown to be congruences according to parallel composition of agents.
Compositional Performance Modelling with the TIPPtool
 PERFORMANCE EVALUATION
, 1998
"... Stochastic Process Algebras have been proposed as compositional specification formalisms for performance models. In this paper, we describe a tool which aims at realising all beneficial aspects of compositional performance modelling, the TIPPtool. It incorporates methods for compositional specificat ..."
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Cited by 53 (19 self)
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Stochastic Process Algebras have been proposed as compositional specification formalisms for performance models. In this paper, we describe a tool which aims at realising all beneficial aspects of compositional performance modelling, the TIPPtool. It incorporates methods for compositional specification as well as solution, based on stateofthearttechniques, and wrapped in a userfriendly graphical front end. Apart from highlighting the general benefits of the tool, we also discuss some lessons learned during development and application of the TIPPtool. A nontrivial model of a real life communication system serves as a case study to illustrate benefits and limitations.
Extended Markovian Process Algebra
, 1996
"... . EMPA enhances the expressiveness of classical process algebras by integrating functional and performance descriptions of concurrent systems. This is achieved by offering, besides passive actions (useful for pure nondeterminism), actions whose duration is exponentially distributed as well as immedi ..."
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Cited by 52 (5 self)
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. EMPA enhances the expressiveness of classical process algebras by integrating functional and performance descriptions of concurrent systems. This is achieved by offering, besides passive actions (useful for pure nondeterminism), actions whose duration is exponentially distributed as well as immediate actions (useful for performance abstraction), parametrized by priority levels (hence prioritized choices) and weights (hence probabilistic choices). In order to analyze an EMPA term, from its integrated semantic model (a transition system labeled on both action types and action durations) we derive a functional semantic model (a transition system labeled on action types only) and a performance semantic model (a Markov chain). We show that an integrated analysis, i.e. a notion of equivalence on the integrated semantic model, is not only convenient but also necessary to achieve compositionality. 1 Introduction The need of integrating the performance modeling and analysis of a concurrent s...
The nature of synchronisation
 Proceedings of the Second International Workshop on Process Algebras and Performance Modelling
, 1994
"... In each of the current stochastic process algebras all noncompetitive interactions between components or agents are modelled using a single combinator, variously called the parallel, synchronisation or cooperation operator. This paper aims to compare the definitions of this combinator which have be ..."
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Cited by 47 (15 self)
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In each of the current stochastic process algebras all noncompetitive interactions between components or agents are modelled using a single combinator, variously called the parallel, synchronisation or cooperation operator. This paper aims to compare the definitions of this combinator which have been used; in particular, looking at the different ways in which rates are associated with the actions which result from such interactions. The implications of the chosen definitions, from a modelling point of view, will be described. When we consider concrete systems rather than abstract representations many different types of interactions between systems are exhibited. Some of these possible interactions are presented in the latter half of the paper and we analyse the extent to which these can be captured using the combinators available in the SPA languages. To conclude some observations about current modelling practice are made together with suggestions of potential extensions to the set of combinators. 1