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Software intensive systems are increasingly expected to deal with changing user needs and dynamic operating conditions at run time. Examples are the need for life recon?gurations, management of resource variability, and dealing with p- ticular failure modes. Endowing systems with these kinds of capabilities poses severe challenges to software engineers and necessitates the development of new techniques, practices, and tools that build upon sound engineering principles. The ?eld of multi-agent systems focuses on the foundations and engineering of systems that consists of a network of autonomous entities (agents) that int- act to achieve the system goals. One line of research in multi-agent systems, inspired by biological, physical and other naturally occurring systems, concerns multi-agent systems in which agents share information and coordinate their - havior througha shared medium called an agentenvironment. Typical examples are gradient ?elds and digital pheromones that guide agents in their local c- text and as such facilitate the coordination of a community of agents. Since environment-mediation in multi-agent systems has shown to result in mana- able solutions with very adaptable qualities, it is a promising paradigm to deal with the increasing complexity and dynamism of distributed applications. Control in environment-mediated multi-agent systems is decentralized, i. e. , noneofthecomponentshasfullaccessorcontroloverthesystem. Self-organization isanapproachtoengineerdecentralized,distributedandresource-limitedsystems thatarecapableofdynamicallyadaptingtochangingconditionsandrequirements without external intervention. This useful system property is often re?ected in functionssuchasself-con?guration,self-optimization,andself-healing. Engine- ing approaches to self-organizing systems often rely on global functionality to emerge from localand autonomous decisions of individual agents that commu- catethroughasharedagentenvironment.

Inhaltsverzeichnis

Frontmatter

Invited Talks

Swarms of Self-assembling Robots

In this talk I present recent research in swarm robotics, the discipline that studies robotic systems composed of swarms of robots tightly interacting and cooperating to reach their goals. In particular, I will present a new type of robot, called swarm-bot, and the results of a number of experiments run with it. A swarm-bot [4,7] is an artifact composed of a swarm of assembled s-bots. The s-bots are mobile robots capable of connecting to, and disconnecting from, other s-bots. In the swarm-bot form, the s-bots are attached to each other and, when needed, become a single robotic system that can move and change its shape. S-bots have relatively simple sensors and motors and limited computational capabilities. A swarm-bot can solve problems that cannot be solved by s-bots alone. In the talk, I first describe the s-bots hardware and the methodology we followed to develop algorithms for their control. Then I illustrate the capabilities of the swarm-bot robotic system by showing video recordings of some of the many experiments we performed to study coordinated movement [1], path formation [8], collective transport [5], shape formation [2,3], and other collective behaviors [6,9,10].
Marco Dorigo

Complex Systems and Agent-Oriented Software Engineering

Although there is a huge amount of work and valuable proposals about agent oriented software engineering, it seems that the paradigm has not been yet widely adopted by software industry. Some claim that there is a need for a killer application showing clearly the benefits of multi-agent systems with respect to other techniques. Others may consider the approach as too academic to be applied in real projects. However, in our opinion, the answer may be found in the simple explanation of lessons learned while developing applications with agent-orientation, and confronting these with object and component oriented solutions, especially when faced to the development of complex systems. This paper discusses contributions of multi-agent systems from a software engineering perspective, as a way to put in value some of the properties of the agent paradigm in the development of complex software systems.
Juan Pavón, Francisco Garijo, Jorge Gómez-Sanz

Engineering Self-organizing Applications

A Characterization of Key Properties of Environment-Mediated Multiagent Systems

The increasing presence of application scenarios which are based on large collections of active components having to adapt continuously to changing environmental requirements has led to several research initiatives with the objective to create new concepts for the design and operation of environment-mediated multiagent systems. In particular, Autonomic Computing (AC) and Organic Computing (OC) have developed the vision of systems possessing life-like properties: They self-organize, adapt to their dynamically changing environments, and establish other so-called self-x properties, like self-healing, self-configuration, self-optimization etc. The impact of these initiatives will depend crucially on our ability to demonstrate the benefits of these systems with respect to some essential properties. Therefore, we need a clear understanding of some key notions like adaptivity, robustness, flexibility, or their degree of autonomy, allowing for self-x properties.
In this paper, a system classification of robust, adaptable, and adaptive systems is presented. Furthermore, a degree of autonomy is characterized to be able to quantify how autonomously a system is working. The degree of autonomy distinguishes and measures external control which is exhibited directly by the user (no autonomy) from internal control of a system which might be fully controlled by an observer/controller architecture that is part of the system (full autonomy). Finally, learning and of trustworthiness are briefly addressed, since these are further essential aspects of self-organizing, adaptive systems.
Hartmut Schmeck, Christian Müller-Schloer

Toward Systemic MAS Development: Enforcing Decentralized Self–organization by Composition and Refinement of Archetype Dynamics

The utilization of self-organizing processes promises scalability, robustness and adaptivity in Multi-Agent Systems (MAS), solely based on decentralized coordination of individual actors. Bionic development approaches have been established, which reuse decentralized coordination mechanisms that are derived from natural self–organizing systems. In this paper, we address analysis activities in incremental MAS development, concerning with the derivation of system architectures that enable applications to meet system requirements. As the functional requirements to self–organizing MAS comprise recurring types of system wide dynamics, we propose a systemic approach to analysis and architectural design activities by the iterative refinement of macroscopic dynamics. Based on a catalog of dynamic models of currently applied environment–mediated design metaphors, we discuss how intended MAS dynamics can be modeled and refined to decentralized MAS designs. A systemic design procedure is proposed and exemplified in a case study that demands the combination of two established design metaphors to enable an projected level of MAS adaptivity.
Jan Sudeikat, Wolfgang Renz

Engineering Systems Which Generate Emergent Functionalities

Complexity of near future and even nowadays applications is exponentially increasing. In order to tackle the design of such complex systems, being able to engineer self-organising systems is a promising approach. This way, the whole system will autonomously changes its behaviour as its parts locally reorganise themselves, always providing an adapted function. This paper proposes to focus on engineering such systems generating emergent functionalities. We will first define two important concepts to take into account in such a context: Emergence and Self-Organisation. Building on these two concepts, we will highlight three main challenges researchers have to cope with: (i) how to control the system at the macro level by only focusing on the design of agents at the micro level, (ii) what kind of tools, models and guides are needed to develop such systems in order to help designers and (iii) how validation of such systems can be achieved? Each of these three challenges will be explained and positioned in regard to the main existing approaches. Our solutions combining emergence and self-organisation will be expounded for each challenge.
Marie-Pierre Gleizes, Valérie Camps, Jean-Pierre Georgé, Davy Capera

Engineering Autonomic Electronic Institutions

There is a growing interest in the study and development of self-* systems motivated by the need for information systems capable of self-management in distributed, open, and dynamic scenarios. Unfortunately,there is a lack of frameworks that support the intricate task of developing self-* systems. We try to make headway along this direction by introducing a framework, EIDE-*, to support the engineering of a particular type of self-* systems, namely autonomic electronic institutions: regulated environments capable of adapting their norms to comply with institutional goals despite the varying behaviours of their participating agents.
Josep Lluís Arcos, Juan A. Rodríguez-Aguilar, Bruno Rosell

Stigmergic Interaction

Prediction Horizons in Agent Models

One motivation for many agent-based models is to predict the future. The nonlinearity of agent interactions in most non-trivial domains mean that the usefulness of such predictions will be limited beyond a certain point (the “prediction horizon”), due to unbounded divergence of their trajectories. The model’s predictions are increasingly useful out to the prediction horizon, but become misleading beyond that point. We exhibit and characterize this behavior in a simple model, based on the polyagent modeling construct, which uses multiple ghost agents mediated through a shared environment to explore alternative futures concurrently for a domain entity. We also discuss how a single agent in such a model can estimate the prediction horizon based on locally available information, and use this estimate to modulate dynamically how far it seeks to look into the future.
H. Van Dyke Parunak, Theodore C. Belding, Sven A. Brueckner

Combining Interface Agents and Situated Agents for Deploying Adaptive Web Applications

A web site presents a graph–like spatial structure composed of pages connected by hyperlinks. This structure may represent an environment in which situated agents associated to visitors of the web site (user agents) are positioned and moved in order to monitor their navigation. This paper presents a heterogeneous multi-agent system supporting the collection of information related to user’s behaviour in a web site by specific situated reactive user agents. The acquired information is then exploited by interface agents supporting advanced adaptive functionalities based on the history of user’s movement in the web site environment. Interface agents also interact with user agents to acquire information on other visitors of the web site and to support a context aware form of interaction among web site visitors.
Andrea Bonomi, Marcello Sarini, Giuseppe Vizzari

Modeling and Structuring Mediating Environments

Situating Cognitive Agents in GOLEM

We investigate the application of a logic-based framework representing an agent environment as a composite structure that evolves over time. Such a complex structure contains the interaction between two main classes of entities: agents and objects. Interactions between these entities are specified in term of events whose occurrence is governed by a set of physical laws specifying the possible evolutions of the agent environment, including how these evolutions are perceived by agents and affect objects and processes in the agent environment. We illustrate the work using GOLEM, a protype platform whose aim is to implement the framework to build situated cognitive agents in a distributed agent environment.
Stefano Bromuri, Kostas Stathis

Modeling Agent-Environment Interactions in Adaptive MAS

In this paper, we discuss a way to model Agent-Environment interactions in adaptive multi-agent systems. We describe the interactions at various levels of abstraction starting with the highest. For each level, we specify the interactions from four viewpoints functional, behavioral, data and structural. This results into a set of models that capture the main properties of agent-environment interactions.
R. Zalila Mili, Renee Steiner

DECIDE: Applying Multi-agent Design and Decision Logic to a Baggage Handling System

Behind the curtains at check-in desks in airports hide a very complex material handling systems, which manage to get your bag transported to the correct departure gate of your flight.
The conventional control software uses a strategy primarily based on a shortest path algorithm, not taking into account dynamical changes or utilization of less packed areas of the BHS.
We changed that perspective towards a decentralized multi-agent based solution by developing strongly collaborating agents. The agents replace the existing control software without modifying the layout of the BHS.
In this paper we describe the BHS problem and the agent-based design. We pay special attention to the impact of the local environments of the agents, and finally give examples of implemented decision strategies.
Kasper Hallenborg, Yves Demazeau

Environment-Based Support for Context and Organizations

Managing Agent Interactions with Context-Driven Dynamic Organizations

Organizations are at the heart of multi-agent systems. To deal with the ongoing dynamics and changes in the system, organizations have to adapt. Typically, agents are responsible to deal with the complexity of organization dynamics. In this paper, we present an approach for context-driven dynamic organizations in which the agent environment takes the burden of managing organization dynamics. Driven by the context, the agent environment manages the evolution of organizations and actively advertises roles to the agents, supporting the necessary collaborations between agents needed in the current context. We introduce a conceptual model for context-driven dynamic organizations and present a software architecture that supports the model in a distributed setting. The proposed approach separates the management of dynamic evolution of organizations from the actual functionality provided by the agents playing roles in the organizations. Separating these concerns makes it easier to understand, design, and manage organizations in multi-agent systems.
We show how we have applied context-driven dynamic organizations in a concrete case of monitoring traffic jams. In this case, camera agents associated with traffic monitoring cameras collaborate in organizations. Depending on the context, camera agents play different roles, with responsibilities ranging from simple measurement to data aggregation. When a traffic jam covers the viewing range of multiple cameras, organizations are dynamically merged, assuring cameras detecting the same traffic jam can collaborate. Vice versa, when a traffic jam dissolves, the organization is dynamically split up. Test results indicate that context-based dynamic organizations is a promising approach to support decentralized traffic monitoring.
Robrecht Haesevoets, Bart Van Eylen, Danny Weyns, Alexander Helleboogh, Tom Holvoet, Wouter Joosen

Modeling and Design of an Agent-Based Micro-simulation of the Swiss Highway Network

Multiagent simulations can be elegantly modeled and designed by enhancing the role of the environment in which agents evolve, called the agent environment. In particular, the agent environment may have the role of a governing infrastructure that regulates with laws or norms the actions taken by the agents. The focus of modeling and design is thus shifted from a subjective view of agents towards a more objective view of the whole multiagent system. In this paper, we apply the idea of a governing environment to model and design a multi-agent system for a micro-simulation of the Swiss highway network. The goal of the simulation is to show how traffic jams and accordion phenomena may be handled with appropriate local regulations on speed limits. A natural modeling would give segments the capacity to regulate the speed based on observed local events. We developed the simulation platform from scratch in order to accommodate our design choices and a realistic complexity. This paper presents in details our modeling and design choices, and first experimental results.
Michael Schumacher, Laurent Grangier, Radu Jurca

Environment Support to the Management of Context Awareness Information

Collaborative Ubiquitous Environments (CUEs) are environments supporting collaboration among persons in a ubiquitous computing setting. This paper shows how results of the research in the Multi–Agent System (MAS) area, and in particular on MAS environments, can be used to model, design and engineer CUEs, with specific reference to the management of context–awareness information. The CUE reference scenario will be introduced, then the Multilayered Multi–Agent Situated System model will be briefly described and applied to represent and to manage several types of awareness information (both physical and logical contextual information). Finally, the paper introduces a prototypal framework based on DJess supporting the definition and management of MMASS based CUEs.
Marco P. Locatelli, Giuseppe Vizzari

Engineering Contextual Information for Pervasive Multiagent Systems

Multiagent systems for mobile and pervasive computing should extensively exploit contextual information both to adapt to user needs and to enable autonomic behavior. This raises the problem of how to represent, organize, aggregate, and make available such data so as to have it become meaningful and usable knowledge, facilitating the design and development of agents, and enabling them to acquire high-degrees of context awareness at limited efforts. In this paper, we identify the key software engineering challenges introduced by the need of accessing and exploiting huge amount of heterogeneous contextual information. Following, we survey the relevant proposals in the area of context-aware pervasive computing, data mining and granular computing discussing their potentials and limitations. On these bases, we propose the W4 model for contextual data and show how it can represent an effective model to enable flexible general-purpose management of contextual knowledge, to facilitate agents in achieving high degrees of context-awareness and, overall, to facilitate the design and development of complex multiagent systems.
Gabriella Castelli, Marco Mamei, Franco Zambonelli

Engineering Business Ecosystems Using Environment-Mediated Interactions

The increasingly complex and dynamic nature of contemporary markets demands that a business engages in an ongoing dialogue with all aspects of its environment, including other cooperative and competitive businesses. Whilst the concept of a business ecosystem captures the essence of such a domain, the lack of a convincing software architecture for its support has resulted in solutions which only partially leverages the potential of the forementioned concept. In this paper, we present an architecture for a business ecosystem supporting application based on Dynamic Agent-based Ecosystem Model (DAEM:) a novel and promising approach to support business ecosystems and their adaptation capabilities where the environment plays an identifiable mediating role.
César A. Marín, Iain Stalker, Nikolay Mehandjiev

Experimenting with Language Support for Proximity in Ambient-Oriented Programming

Proximity is a key to scalable and meaningful interactions in distributed systems, both natural and artificial, and in particular in pervasive computing environments. However, proximity as such is a vague notion that can be considered both in a very factual manner (spatial distance) and in a very abstract and subjective manner (user affinity). We claim that an adequate system or programming language for ambient intelligence applications ought to support an open notion of proximity, making it possible to rely on different, possibly subjective, understandings of proximity, as well as their combinations. We explore how to extend the Ambient-Oriented Programming language AmbientTalk with language constructs that give programmers flexible control over subjective proximity definitions in both service advertising and discovery.
Victor Ramiro, Jessie Dedecker, Éric Tanter, Peter Barron

Environment-Supported Roles to Develop Complex Systems

Interactions represent an important issue to be faced in the development of complex agent systems, and deserve for appropriate support. In this context, roles have been successfully exploited to design and deal with agent interactions. In this paper we explain how the role management can be supported by the environment and which the related advantages are. We will also present an infrastructure, RoleX, that can be exploited to accomplish this task.
Giacomo Cabri

Backmatter

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