A Stochastic Pi Calculus for Concurrent Objects

International audienceWe present SpiCO, a new modeling and simulation language for system biology, based on the stochastic pi-calculus. SpiCO supports higher level modeling via multi-profile concurrent objects with static inheritance. We present a semantics for SpiCO in terms of continuous time Markov chains, and show how to compile SpiCO back into the biochemical stochastic pi-calculus while preserving semantics

MiKO---Mikado Koncurrent Objects

The motivation for the Mikado migration model is to provide programming constructs for controlling code mobility that are as independent as possible from the particular programming language used to program the code. The main idea is to regard a domain (or site, or locality), where mobile code may enter or exit, as a membrane enclosing running processes, and offering services that have to be called for entering or exiting the domain. MiKO---Mikado Koncurrent Objects is a particular instance of this model, where the membrane is explicitly split in two parts: the methods defining the interface, and a process part describing the data for, and the behavior of, the interface. The talk presents the syntax, operational semantics, and type system of MiKO, together with an example. It concludes by briefly mentioning the implementation of a language based on the calculus

A Stochastic Pi Calculus for Concurrent Objects

International audienceWe present SpiCO, a new modeling and simulation language for system biology, based on the stochastic pi-calculus. SpiCO supports higher level modeling via multi-profile concurrent objects with static inheritance. We present a semantics for SpiCO in terms of continuous time Markov chains, and show how to compile SpiCO back into the biochemical stochastic pi-calculus while preserving semantics

An algebra of behavioural types

Special thanks to Gérard Boudol, Ilaria Castellani, Silvano Dal Zilio, and Massimo Merro, for fruitful discussions and careful reading of parts of this document. Several anonymous referees made useful comments.We propose a process algebra, the Algebra of Behavioural Types, as a language for typing concurrent objects. A type is a higher-order labelled transition system that characterises all possible life cycles of a concurrent object. States represent interfaces of objects; state transitions model the dynamic change of object interfaces. Moreover, a type provides an internal view of the objects that inhabits it: a synchronous one, since transitions correspond to message reception. To capture this internal view of objects we define a notion of bisimulation, strong on labels and weak on silent actions. We study several algebraic laws that characterise this equivalence, and obtain completeness results for image-finite types.publishersversionpublishe

On the design and implementation of a virtual machine for process calculi

Dissertação de Doutoramento em Ciência de Computadores apresentada à Faculdade de Ciências da Universidade do Port

Static analysis of an actor-based process calculus by abstract interpretation

Le modèle des Acteurs, introduit par HEWITT et AGHA à la fin des années 80, décrit un système concurrent comme un ensemble d'agents autonomes au comportement non uniforme et communiquant de façon point-à-point par l'envoi de messages étiquetés. Le calcul CAP, proposé par COLAÇO, est un calcul de processus basé sur ce modèle qui permet de décrire sans encodage complexe des systèmes réalistes non triviaux. Ce calcul permet, entre autre, la communication de comportements via les messages et est, en ce sens, un calcul d'ordre supérieur. L'analyse de propriétés sur ce calcul a déjà fait l'objet de plusieurs travaux, essentiellement par inférence de type en utilisant des types comportementaux et du sous-typage. Par ailleurs, des travaux plus récents, effectués par VENET puis FERET, proposent une utilisation de l'interprétation abstraite pour l'analyse de calculs de processus. Ces approches permettent de calculer des propriétés non uniformes : elles permettent, par exemple, de différencier les instances récursives d'un même processus. Cette thèse s'inscrit donc dans la suite de ces deux approches, en appliquant l'interprétation abstraite à l'analyse de CAP. Suivant le cadre proposé par FERET, CAP est, tout d'abord, exprimé dans une forme non standard facilitant les analyses. L'ensemble des configurations atteignables est ensuite sur-approximé via une représentation, correcte par construction, dans des domaines abstraits. Des domaines abstraits généraux sont ensuite introduits afin d'améliorer les analyses existantes ou de représenter des propriétés locales à un sous-terme. Des propriétés spécifiques à CAP, la linéarité des termes et l'absence de messages orphelins, sont alors étudiées dans ce cadre. Des domaines spécifiques sont définis et utilisés pour vérifier ces propriétés. Le cadre présenté permet de lever toutes les restrictions existantes des analyses précédentes quant à la forme des termes ou l'utilisation du passage de comportement. L'intégralité des analyses présentées a été implantée dans un prototype. ABSTRACT : The Actor model, introduced by HEWITT and AGHA in the late 80s, describes a concurrent communicating system as a set of autonomous agents, with non uniform interfaces and communicating by the use of labeled messages. The CAP process calculus, proposed by COLAÇO, is based on this model and allows to describe non trivial realistic systems, without the need of complex encodings. CAP is a higher-order calculus: messages can carry actor behaviors. Multiple works address the analysis of CAP properties, mainly by the use of inferencebased type systems using behavioral types and sub-typing. Otherwise, ore recent works, by VENET and later FERET, propose the use of abstract interpretation to analyze process calculi. These approaches allow to compute non-uniform properties. For example, they are able to differentiate recursive instances of the same thread. This thesis is at the crossroad of these two approaches, applying abstract interpretation to the analysis of CAP. Following the framework of FERET, CAP is firstly expressed in a non standard form, easing its analysis. The set of reachable states is then over-approximated via a sound by construction representation within existing abstract domains. New general abstract domains are then introduced in order to improve the accuracy of existing analyses or to represent local properties. CAP specific properties such as the linearity of terms or the absence of orphan messages, are then considered in this framework. Specific abstract domains are defined and used to check these properties. The proposed framework is able to relax any existing restriction of previous analyses such as constraints on the shape of terms or limitation in the use of CAP behavior passing. The whole analyses have been implemented in a prototyp

A Typing System for a Calculus of Objects

The present paper introduces an implicitly typed object calculus intended to capture intrinsic aspects of concurrent objects communicating via asynchronous message passing, together with a typing system assigning typings to terms in the calculus. Types meant to describe the kind of messages an object may receive are assigned to the free names in a program, resulting in a scenario where a program is assigned multiple name-type pairs, constituting a typing for the process. Programs that comply to the typing discipline are shown not to suffer from runtime errors. Furthermore the calculus possesses a notion of principal typings, from which all typings that make a program well-typed can be extracted. We present an efficient algorithm to extract the principal typing of a process. 1 Introduction Most of the attempts to introduce some type discipline into object-oriented languages start from lambda-calculus, by extending this with some kind of records. There are several limitations to this ap..