Foundation publications

Here, thesis or proof of concepts that founded the main concepts of MECSYCO :

Multi-agent Environment for Multi-Modeling and Simulation of Complex Systems

| Benjamin Camus

This thesis is focused on the study of complex systems through a modeling and simulation (M&S) process. Most questions about such systems requiere to take simultaneously account of several points of view. Phenomena evolving at different (temporal and spatial) scales and at different levels of resolution (from micro to macro) have to be considered. Moreover, several expert skills belonging to different scientific fields are needed. The challenges are then to reconcile these heterogeneous points of view, and to integrate each domain tools (formalisms and simulation software) within the rigorous framework of the M&S process. In order to solve these issues, we mobilise notions from multi-level modeling, hybrid modeling, parallel simulation and software engineering. Regarding these fields, we study the complementarity of the AA4MM approach and the DEVS formalism into the scope of the model-driven engineering (MDE) approach. Our contribution is twofold. We propose the operational specifications of the MECSYCO co-simulation middleware enabling the parallel simulation of complex systems models in a rigorous and decentralized way. We also define an MDE approach enabling the non-ambiguous description of complex systems models and their automatic implementation in MECSYCO. We show the properties of our approach with several proofs of concept.

Thesis

Multi-agent approach for multi-modeling and simulation coupling. Application to ubiquitous networks.

| Julien Siebert

This work has been done between the fields of ubiquitous networks and multi-agent based simulation. The main context is to study mutual influences existing between ubiquitous network performances and their users' behaviors. We have highlighted the need for reusing and coupling modelling and simulation softwares together in order to simultaneously integrate several abstraction levels in the study. We target those needs by a multi-agent approach and we propose a metamodel: AA4MM. The core idea in AA4MM is to build a society of models, simulators and simulation softwares that solves the core challenges of multi-modelling and simulation coupling in an homogeneous perspective. AA4MM major contributions are the possibility to easily reuse, to make interoperable and modular existing heterogeneous models and softwares, to manage scale changes and a simulation algorithm fully decentralized. We apply this metamodel to the field of ubiquitous networks in order to target the question of mutual influences between networks performances and users' behaviors.

Thesis

Hybrid Co-simulation of FMUs using DEV&DESS in MECSYCO

| Benjamin Camus, Virginie Galtier, Mathieu Caujolle, Vincent Chevrier, Julien Vaubourg, Laurent Ciarletta, Christine Bourjot

Co-simulation is a key tool in the design and operation of a growing number of complex cyber-systems. But efficiently yet accurately combining continuous time components (such as FMUs) with event-based ones can be challenging, both from a modeling perspective and an operational, tools-oriented one. We propose a platform to tackle this problem building up on MECSYCO, a MAS-based DEVS wrapping platform dedicated to co-simulation. Relying on the ability of DEVS to integrate the DEV&DESS formalism -which offers a sound framework for describing hybrid models- we propose a DEV&DESS wrapper for FMU. This wrapper encapsulates a version of the DEV&DESS simulation algorithm for FMU components which is notably composed of: (1) a forecast strategy which searches for the next state-event; (2) a bisectional algorithm to approach the location of the state-change in an FMU. Our solution is implemented using Java and JavaFMI to control the FMU. Our sample case is the co-simulation of a barrel-filler factory implemented in different FMUs and event-based models. Compared to related works, our proposal is functional, generic, yet evolutionary, and benefits from the strong foundations of DEV&DESS.

Conference paper

Co-Simulation of IP Network Models in the Cyber-Physical Systems Context, using a DEVS-based Platform

| Julien Vaubourg, Vincent Chevrier, Laurent Ciarletta, Benjamin Camus

Cyber-Physical Systems (smart grids, cities, homes, etc) are composed of computing resources, actuators and sensors , connected through IP networks. These IP networks involve many technologies. In order to help designing and evaluating these systems, we are studying the modeling and simulation of IP networks in this context. Since there is no universal IP simulator proposing a model library corresponding to all the required technologies, we propose a solution to make different major IP simulators, generally not interoperable, interact with one another in a same co-simulation. Moreover, they should also interact with simu-lators corresponding to other fields of expertise involved in the simulation, mostly related to the physical or social aspects of these systems (e.g. power models, traffic models, weather models, etc). In this paper, we propose to address these issues as a multi-modeling problem, by integrating well-known IP network simulators into a DEVS-based co-simulation platform. We propose some concepts, helping to split a network topology into several models, to create input/output ports inside them, and to integrate them to a DEVS multi-model. We illustrate our solution thanks to a use case, including interconnected event-based models executed both by NS-3 and OMNeT++, equation-based models and the co-simulation platform MECSYCO.

Conference paper

Multi-modeling and co-simulation-based mobile ubiquitous protocols and services development and assessment

| Tom Leclerc, Julien Siebert, Vincent Chevrier, Laurent Ciarletta, Olivier Festor

Mobile and Ubiquitous Computing is about interconnected computing resources embedded in our daily lives and providing contextual services to users. The real influence between user behavior and ubiquitous communication protocols performance and operation needs to be taken into account at the protocol design stage. Therefore, we provide a generic multi-modeling approach that allows us to couple a user behavior model with a network model. To allow both assessment and benchmarking of ubiquitous solutions, we define formal reference scenarios based on the selection of a set of environmental conditions (contexts). We illustrate the use of the framework through its application to the study of mutual influences of mobility models and ad hoc network protocols

Conference paper

Agents and artefacts for multiple models co-evolution Building complex system simulation as a set of interacting models

| Julien Siebert, Laurent Ciarletta, Vincent Chevrier

Complex systems simulations generally involve the interaction of different scientific fields. Human economies, ecosystems or dynamic computer networks such as P2P are good examples. Since models and simulators already exist in those fields, designing the simulation as a society of interacting and co-evolving models appears attractive. Beyond the technical issues to make different simulators cooperate, the challenges are to make the co-evolution design and implementation easier for the users that rarely know intricate modelling and simulation tools, and to facilitate the collaboration of different experts. Agents and artefacts (A&A) paradigm simplifies the design and the implementation of a society of interacting and co-evolving models. That is, the addition, the removal or the interchange of models require less effort. Contrary to classical approaches, we have built a decentralized co-evolution architecture based upon A&A and a data-driven coordination model. In this article, beyond the architecture presentation, we focus on the benefit provided by A&A used for multiple models co-evolution.

Conference paper

Other publications

Here you can find several publications made by the people who are working or worked on MECSYCO

Study about decomposition and integration of continuous systems in discrete environment

| Thomas Paris, Alexandre Tan, Vincent Chevrier, Laurent Ciarletta

A complex system is one composed of many interacting heterogeneous entities. This kind of system can be dealt with multi-modeling and co-simulation but individual models may also be heterogeneous (continuous , discrete, event-based...). To manage this complexity , we use MECSYCO (Multi-agent Environment for Complex-SYstem CO-simulation) a DEVS compliant environment for co-simulation. MECSYCO handles heterogeneity issues, but the number of models which may interact during a co-simulation of a complex system raises also performance issues. So it's important to develop performance measurement tools to study MECSYCO's co-simulation performances. In this article we present modular performance measurement tools for MECSYCO. We test these tools on our " Multi-Room Heating " model, a scalable continuous system, to assert the tradeoff between accuracy and computational time when integrating continuous system in a discrete modeling environment. Then we study the impact of decomposing a continuous system contained in one FMU into several FMUs which interact. We verify the validity of our tools and we show that, under some conditions, a large model that cannot be solved on one block, can be decomposed into smaller ones, solved and simulated in a co-simulation on MECSYCO without significant loss of accuracy.

Conference paper

Multi-agent multi-model simulation of smart grids in the MS4SG project

| Julien Vaubourg, Yannick Presse, Benjamin Camus, Christine Bourjot, Laurent Ciarletta, Vincent Chevrier, Jean-Philippe Tavella, Hugo Morais

This paper illustrates how the multi-agent approach, or paradigm, can help in the modeling and the simulation of smart grids in the context of MS4SG (a joint project between LORIA-INRIA and EDF R&D). Smart grids simulations need to integrate together pre-existing and heterogeneous models and their simulation software; for example modeling tools of the power grids, of telecommunication networks, and of the information and decision systems. This paper describes the use of MECSYCO as a valid approach to integrate these heterogeneous models in a multi-agent smart grid simulation platform. Several use cases show the ability of MECSYCO to effectively take into account the requirements of smart grids simulation in MS4SG

Conference paper

Co-Simulation of IP Network Models in the Smart Grids Context, using a DEVS-based Platform.

| Julien Vaubourg, Vincent Chevrier, Laurent Ciarletta

We are interested in the modeling and simulation of the IP networks as the communication layer for smart grids. In this context, a network can involve many different technologies, and the available models corresponding to these technologies may be implemented in different simulation software. As a result, thanks to their own models libraries, different IP network simulators can be complementary. However, these simulators are not all interoperable with each other, and therefore cannot be yet all integrated in a same co-simulation. Moreover, the network simulators have to interact with the other simulators corresponding to other areas of expertise involved in the smart grids simulations. Integrating this requires to consider the multi-formalism problems. Our approach is to integrate IP network simulators to the DEVS-based co-simulation platform MECSYCO (formally named AA4MM). Thanks to this approach, different network simulators can exchange simulated IP packets. In this paper, we illustrate how we integrated the NS-3 simulator into MECSYCO.

Pre-publication

Combining DEVS with multi-agent concepts to design and simulate multi-models of complex systems (WIP)

| Benjamin Camus, Christine Bourjot, Vincent Chevrier

We are interested in the multi-modeling and simulation of complex systems, that is representing a complex system as a set of interacting models and simulating it with a co-simulation approach. Representing and simulating a complex system multi-model requires to integrate heterogeneity at several levels (representations, formalisms, simulation software, models' interactions.. .). In this article, we present our approach that consists of combining the Discrete EVent System Specification (DEVS) formalism and multi-agent concepts in order to achieve these requirements. The use of the DEVS formalism enables a rigourous integration of models described with heterogeneous formalisms and a rigourous simulation protocol. Multi-agent concepts ease the description of multi-perspective integration and the reuse of existing heterogeneous simulators. We detail the combination of both in the Agent & Artifact for Multi-Modeling (AA4MM) approach and illustrate its use in a proof of concept.

Conference paper

Multi-level Modeling as a Society of Interacting Models

| Benjamin Camus, Christine Bourjot, Vincent Chevrier

We propose to consider a multi-level representation from a multi-modeling point of view. We define a framework to better specify the concepts used in multi-level modeling and their relationships. This framework is implemented through the AA4MM meta-model, which benefits from a middleware layer. This meta-model uses the multi-agent paradigm to consider a multi-model as a society of interacting models. We extend this meta-model to consider multi-level modeling and present a proof of concept of a collective motion example where we show the ability of this approach to rapidly change from one pattern of interaction to another one by reusing some of the meta-model's components.

Report

Modélisation multi-niveaux dans AA4MM

| Benjamin Camus, Julien Siebert, Christine Bourjot, Vincent Chevrier

In this article, we propose to represent a multi-level phenomenon as a set of interacting models. This perspective makes the levels of representation and their relationships explicit. To deal with coherence, causality and coordination issues between models, we rely on AA4MM, a metamodel dedicated to such a representation. We illustrate our proposal and we show the interest of our approach on a flocking phenomenon.

Conference paper

Impact des dimensions spatiale et temporelle dans la modélisation d'un phénomène collectif de type free-riding

| Tomas Navarrete Gutierrez, Julien Siebert, Laurent Ciarletta, Vincent Chevrier

We present a comparison of five different models built upon the same individual behavior hypothesis of a collective phenomenon present in peer-to-peer file exchange networks: "free-riding". We study a global analytical model and four agent based models. Multi-agent models include the space and time dimensions rarely seen in the literature discussing aggregated models of the collective phenomenon in question. We discuss the a priori and the experimental conditions under which the models are equivalent. We demonstrate that one individual decision algorithm can lead to contradictory information.

Conference paper

Agents and Artefacts for Multiple Models coordination. Objective and decentralized coordination of simulators.

| Julien Siebert, Laurent Ciarletta, Vincent Chevrier

Complex systems simulation implies the interaction of different scientific fields. However, most of the time people involved into the simulation process do not know intricate distributed simulation tools and only care about their own domain modelling. We propose a framework (called AA4MM) to build a simulation as a society of interacting models. The main goal is to reuse existing models and simulators and to make them interact. The coordination challenges remain to the AA4MM framework so that the simulation design and implementation stay as simple as possible. In this paper, we present the coordination model which intends to decentralize the simulators interactions. We propose to use the environment through the notion of artefact in order to deal with the coherence, compatibility and coordination issues that appear in parallel simulations.

Conference paper

AA4MM coordination model and event-B specification

| Julien Siebert, Joris Rehm, Vincent Chevrier, Laurent Ciarletta, Dominique Méry

We develop a framework called Agent and Artefact for Multiple Models coordination (AA4MM) . It is is intended to make the design and the implementation of complex systems simulation modular and decentralized. Our main goal is to reuse existing models and simulators and to make them interact in order to simulate dierent levels of abstraction. The main constraint is that people involved into the design process do not have to care about anything else but modelling. Coordination challenges remain to the framework. This report presents the event-B specication of the coordination model proposed in [SCC10]. Its goal is to check that the system is never blocked (no deadlock): no simulator is waiting for another indenitely.

Report

De l'intérêt du couplage de modèles pour appréhender les interactions utilisateurs-réseaux dynamiques

| Julien Siebert, Laurent Ciarletta, Vincent Chevrier

Cet article s'inscrit dans le cadre de l'étude des systèmes complexes via la modélisation et la simulation informatique. Nous pensons qu'il est parfois nécessaire de faire interagir plusieurs modèles pour simuler un phénomène. Dans le cas des technologies des réseaux dynamiques (réseaux P2P, réseaux mobiles Ad Hoc), le comportement des usagers et le fonctionnement des réseaux s'influencent mutuellement. Nous proposons une approche de modélisation et un outil de simulation couplant un modèle d'utilisateurs - basé sur le paradigme multi-agents - et un modèle de réseaux dynamiques. Nous discutons, au travers d'un cas d'étude particulier, des avantages, des problématiques soulevées et des limitations d'une telle approche. Nous montrons que cette démarche de modélisation apporte un niveau de précision et une flexibilité élevés.

Review Article

Impact du comportement des utilisateurs dans les réseaux pair-à-pair P2P modélisation et simulation multi-agents

| Julien Siebert, Laurent Ciarletta, Vincent Chevrier

Dans cet article, nous présentons les interconnexions qui peuvent se faire entre, d'une part, la modélisation et simulation multi-agents, et le domaine des réseaux pair-à-pair (P2P) d'autre part. Plus particulièrement, dans ce domaine, nous traitons de la prise en compte, dans les modèles de simulation, des comportements de l'utilisateur sur l'une des caractéristiques du fonctionnement de ces réseaux : la qualité de service. Dans un premier temps, nous montrons les caractéristiques qui nous semblent souhaitables pour modéliser de manière adéquate de tels réseaux, montrons les limites actuelles que nous constatons dans le domaine multi-agents et proposons une approche multi-modèles. Dans un second temps, nous détaillons la mise en oeuvre de cette proposition puis validons son bien-fondé en détaillant quelques expérimentations réalisées qui montrent que notre outil correspond bien à nos attentes de modélisation.

Conference paper

Entwined influences of users' behaviour and QoS a multi-model approach

| Julien Siebert, Vincent Chevrier, Laurent Ciarletta

In distributed, dynamic networks and applications, such as Peer-to-Peer (P2P), users' behaviour and quality of service/quality of experiment are known to influence each other. In worst cases, these mutual influences could lead the system to crash. We propose a novel approach to model relationships between users and QoS. It is based upon multi-agent systems in order to study the impact of situated behaviours on the global network and to integrate different levels of representation (users' behaviour, overlay protocols, network topology). This paper describes our approach to represent the different models required in such systems and a first implementation in an existing overlay simulator with the first results of experimentations.

Conference paper

Agent-based modelization for p2p networks

| Julien Siebert

Conference paper

Modélisation multimodèle des réseaux dynamiques cas des réseaux pair-à-pair

| Julien Siebert, Vincent Chevrier, Laurent Ciarletta

Dans cet article, nous présentons une démarche conceptuelle liant des modélisations issues des mondes pair-à-pair et multi-agents afin de prendre en compte le comportement de l'utilisateur dans la modélisation et la simulation des réseaux pair-à-pair. Nous présentons aussi un outil de simulation que nous avons adapté ainsi que nos premiers résultats qui indiquent que cette démarche est cohérente.

Conference paper

Impact du comportement des utilisateurs dans les réseaux pair-à pair, modélisation et simulation multi-agents

| Julien Siebert

Network access and services are becoming ubiquitous, and the number of their users and usage is still growing rapidily. Controlling those networks is incresaingly complex. At the same time, the notion of infrastructure is also shaken by new technologies such as P2P or adhoc networks. Standard control and evaluation mechanism are not taking into account the complexity, diversity and dynamicity of the users' behavior, which are the subject of study of multi-agent simulation. This document explores the opportunity to bridge the usual networking modelling and simulation tools with the multi-agent approach.

Report