MODEST: A Compositional Modeling Formalism for Hard and Softly Timed Systems

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. The language contains features such as simple and structured data types, structuring mechanisms like parallel composition and abstraction, means to control the granularity of assignments, exception handling, and nondeterministic and random branching and timing. MODEST can be viewed as an overarching notation for a wide spectrum of models, ranging from labeled transition systems to timed automata (and probabilistic variants thereof), as well as prominent stochastic processes such as (generalized semi-)Markov chains and decision processes. The paper describes the design rationales and details of the syntax and semantics.

Ten Years of Performance Evaluation for Concurrent Systems Using CADP

“…First of all, the Cunctator tool opens an analysis avenue, based on discrete-event simulation, that does not suffer from the state space explosion, is straightforward to parallelize, and can support distributions that are not restricted by the Markov property. We are exploring this avenue in relation to discrete-event simulation activities revolving around the Modest language and tool [23].…”

Synthesis and stochastic assessment of cost-optimal schedules

“…Simulations are executed with the performance evaluation tool MÖBIUS [18]. Simulation models are specified in the MODEST language [17,12].…”

“…MODEST is a formal language to describe stochastic timed systems [17,12], equipped with a rigid formal semantics. The functional core of MODEST can be considered as a simple process algebra enriched with some convenient language constructs.…”

“…We assess the schedules by simulation, making reasonable assumptions about the failure behaviour of resources. We create a simulation model of the lacquer production plant using the modelling language MODEST [12], and simulate the 29 orders according to the generated schedule with the simulator of the performance tool MÖBIUS [16,18,11]. The quintessence of this study is that schedules generated with extended processing time have more chance to miss the due date than schedules based on net processing times.…”

Symbolic Verification and Strategy Synthesis for Linearly-Priced Probabilistic Timed Automata

“…A second tool supporting PTAs is mcpta [20], which applies the digital clocks abstraction to translate a subset of the modelling language Modest [15] directly into the PRISM modelling language. The related problem of price-bounded probabilistic reachability [10] (known to be undecidable [9]) can be analysed via a semi-decision procedure using priced zones, implemented in Fortuna [11].…”