MoDeST - A Modelling and Description Language for Stochastic Timed Systems (original) (raw)
MODEST: A modelling language for stochastic timed systems
This paper presents a modelling language, called MoDeST, for describing the behaviour of discrete event systems. The language combines conventional programming constructs -such as iteration, alternatives, atomic statements, and exception handling -with means to describe complex systems in a compositional manner. In addition, MoDeST incorporates means to describe important phenomena such as non-determinism, probabilistic branching, and hard real-time as well as soft real-time (i.e., stochastic) aspects. The language is influenced by popular and user-friendly specification languages such as Promela, and deals with compositionality in a light-weight process-algebra style. Thus, MoDeST (i) covers a very broad spectrum of modelling concepts, (ii) possesses a rigid, process-algebra style semantics, and (iii) yet provides modern and flexible specification constructs.
Specification of Stochastic Properties in Real-Time Systems
1996
In this paper we present a new approach to the formal speci cation of distributed real-time systems using the formal description technique LOTOS together with a stochastic temporal logic STL. This approach previously presented in the context of LOTOS/QTL, is characterized by a separation of concerns. The functional behaviour is described in LOTOS without regard for the time critical constraints. The speci cation is then extended with precise real-time requirements written in STL. We present a method to generate a timing event scheduler from the requirements in order to monitor the functional behaviour.
MoDeST: A compositional modeling formalism for hard and softly timed systems
2006
Abstract This paper presents MODEST (modeling and description language for stochastic timed systems), a formalism that is intended to support 1) the modular description of reactive systems' behavior while covering both 2) functional and 3) nonfunctional system aspects such as timing and quality-of-service constraints in a single specification.
2015
Cette these propose une methodologie qui integre les methodes formelles dans la specification, la conception, la verification et la validation des systemes complexes concurrents et distribues avec une perspective a evenements discrets. La methodologie est basee sur le langage graphique HILLS (High Level Language for System Specification) que nous avons defini. HiLLS integre des concepts de genie logiciel et de theorie des systemes pour une specification des systemes. Precisement, HiLLS integre des concepts et notations de DEVS (Discrete Event System Specification), UML (Unified Modeling Language) et Object-Z. Les objectifs de HILLS incluent la definition d’une syntaxe concrete graphique qui facilite la communicabilite des modeles et plusieurs domaines semantiques pour la simulation, le prototypage, l’enaction et l’accessibilite a l’analyse formelle. L’Enaction se definit par le processus de creation d’une instance du systeme qui s’execute en temps reel (par opposition au temps virtu...
A formal framework for stochastic discrete event system specification modeling and simulation
Simulation, 2010
We introduce an extension of the classic Discrete Event System Specification (DEVS) formalism that includes stochastic features. Based on the use of the probability spaces theory we define the stochastic DEVS (STDEVS) specification, which provides a formal framework for modeling and simulation of general non-deterministic discrete event systems. The main theoretical properties of the STDEVS framework are treated, including a new definition of legitimacy of models in the stochastic context and a proof of STDEVS closure under coupling. We also illustrate the new stochastic modeling capabilities introduced by STDEVS and their relation with those found in classic DEVS. Practical simulation examples are given involving performance analysis of computer systems and hybrid modeling of networked control systems, applications where the modeling of stochastic components is vital.
Formal Techniques, Modelling and Analysis of Timed and Fault-Tolerant Systems
Lecture Notes in Computer Science, 2004
We consider a general notion of timed automata with inputdetermined guards and show that they admit a robust logical framework along the lines of [6], in terms of a monadic second order logic characterisation and an expressively complete timed temporal logic. We then generalise these automata using the notion of recursive operators introduced by Henzinger, Raskin, and Schobbens [9], and show that they admit a similar logical framework. These results hold in the "pointwise" semantics. We finally use this framework to show that the real-time logic MITL of Alur et al [2] is expressively complete with respect to an MSO corresponding to an appropriate input-determined operator.
A Language for Formal Description of Real Time Systems
Safety of Computer Control Systems 1983 (Safecomp '83), 1983
A new language for formal description of large real time systems is presented. It is developed in the Central Research Laboratory of Thomson CSF (1). Its temporary name is L. The real time part of L is based on a model of parallel calculus for which denotational semantics was supplied. The language has been tested in particular on examples of outcoming calls in a swithching network and CCITT number 7 protocol. At the moment the language environment includes a parser, a translator into a model related to Petri nets and the corresponding anlyser.
A probabilistic language formalism for stochastic discrete-event systems
IEEE Transactions on Automatic Control, 1999
The formalism of probabilistic languages has been introduced for modeling the qualitative behavior of stochastic discrete event systems. A probabilistic language is a unit interval valued map over the set of traces of the system satisfying certain consistency constraints. Regular language operators such as choice, concatenation, and Kleene-closure have been defined in the setting of probabilistic languages to allow modeling of complex systems in terms of simpler ones. The set of probabilistic languages is closed under such operators, thus forming an algebra. It also is a complete partial order under a natural ordering in which the operators are continuous. Hence recursive equations can be solved in this algebra. This is alternatively derived by using the contraction mapping theorem on the set of probabilistic languages which is shown to be a complete metric space. The notion of regularity, i.e., finiteness of automata representation, of probabilistic languages has been defined and it is shown that regularity is preserved under choice, concatenation, and Kleene-closure. We show that this formalism is also useful in describing system performance measures such as completion time, reliability, etc. and present properties to aide their computation.
A process algebraic framework for specification and validation of real-time systems
Formal Aspects of Computing, 2009
Following the trend to combine techniques to cover several facets of the development of modern systems, an integration of Z and CSP, called Circus , has been proposed as a refinement language; its relational model, based on the unifying theories of programming (UTP), justifies refinement in the context of both Z and CSP. In this paper, we introduce Circus Time , a timed extension of Circus , and present a new UTP time theory, which we use to give semantics to Circus Time and to validate some of its laws. In addition, we provide a framework for validation of timed programs based on FDR, the CSP model-checker. In this technique, a syntactic transformation strategy is used to split a timed program into two parallel components: an untimed program that uses timer events, and a collection of timers. We show that, with the timer events, it is possible to reason about time properties in the untimed language, and so, using FDR. Soundness is established using a Galois connection between the u...