International audienceTo program parallel systems efficiently and easily, a wide range of programming models have been proposed, each with different choices concerning synchronization and communication between parallel entities. Among them, the actor model is based on loosely coupled parallel entities that communicate by means of asynchronous messages and mailboxes. Some actor languages provide a strong integration with object-oriented concepts; these are often called active object languages. This paper reviews four major actor and active object languages and compares them according to carefully chosen dimensions that cover central aspects of the programming paradigms and their implementation

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The value of verification of cyberphysical systems depends on the relationship between the state of the software and the state of the physical system. This relationship can be complex because of the real-time nature and different timelines of the physical plant, the sensors and actuators, and the software that is almost always concurrent and distributed. In this paper, we study different ways to construct a transition system model for the distributed and concurrent software components of a CPS. The purpose of the transition system model is to enable model checking, an established and widely used verification technique. We describe a logical-time-based transition system model, which is commonly used for verifying programs written in synchronous languages, and derive the conditions under which such a model faithfully reflects physical states. When these conditions are not met (a common situation), a finer-grained event-based transition system model may be required. We propose an approach for formal verification of cyberphysical systems using Lingua Franca, a language designed for programming cyberphysical systems, and Rebeca, an actor-based language designed for model checking distributed event-driven systems. We focus on the cyber part and model a faithful interface to the physical part. Our method relies on the assumption that the alignment of different timelines during the execution of the system is the responsibility of the underlying platforms. We make those assumptions explicit and clear.

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C e n t r u m v o o r W i s k u n d e e n I n f o r m a t i c aSymmetry and partial order reduction techniques in model checking Rebeca ABSTRACT Rebeca is an actor-based language with formal semantics that can be used in modeling concurrent and distributed software and protocols. In this paper, we study the application of partial order and symmetry reduction techniques to model checking dynamic Rebeca models. Finding symmetry based equivalence classes of states is in general a difficult problem known to be as hard as graph isomorphism. We show how, for Rebeca models, we can tackle this problem with a polynomial-time solution. Moreover, the coarse-grained interleaving semantics of Rebeca causes considerable reductions when partial order reduction is applied. We have also developed a tool that can make use of both techniques in combination or separately. The evaluation results show significant improvements in model size and model-checking time. Abstract Rebeca is an actor-based language with formal semantics that can be used in modeling concurrent and distributed software and protocols. In this paper, we study the application of partial order and symmetry reduction techniques to model checking dynamic Rebeca models. Finding symmetrybased equivalence classes of states is in general a difficult problem known to be as hard as graph isomorphism. We show how, for Rebeca models, we can tackle this problem with a polynomial-time solution. Moreover, the coarse-grained interleaving semantics of Rebeca causes considerable reductions when partial order reduction is applied. We have also developed a tool that can make use of both techniques in combination or separately. The evaluation results show significant improvements in model size and model-checking time.

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