Catálogo de publicaciones - libros

We argue that it is useful to study classes of Multi-Agent System () architectures, corresponding to architectural styles in addition to particular architectures. In this work we focus on a particular abstraction level where architectural styles are characterized according to properties, such as, the type of control used (from fully centralized to fully distributed), and the type of coordination used. Different architectural styles support different quality attributes to different extent. When choosing architectural style for a given application domain, we argue that it is important to evaluate the them according to the quality attributes relevant to that application. The architectural style that provides the most appropriate balance between these attributes should then be selected. As a case study we investigate the problem of dynamic and distributed resource allocation and compare six architectural styles that can be used to handle this task. We also illustrate the use of the Analytic Hierarchy Process, which is a basic approach to select the most suitable alternative from a number of alternatives evaluated with respect to several criteria, for selecting the architectural style that balance the trade-off between the relevant quality attributes in the best way.

A crucial part of multi-agent system design is the design of agent interactions. Traditional approaches to designing agent interaction use interaction protocols, which focus on defining legal sequences of messages. Such approaches do not naturally exhibit flexibility and robustness, and are not a good match for intelligent software agents which are autonomous, proactive, flexible and robust. The approach to designing agent interaction uses interaction goals, actions, and a number of failure recovery mechanisms to give a design methodology which is a good fit with intelligent software agents. However, the Hermes approach only covers part of the design process. In this paper we integrate Hermes with the Prometheus methodology, thus providing a complete methodology for designing multi-agent systems where interaction design is goal-oriented, yielding flexible and robust interactions.

Tropos is an agent-oriented development methodology based on knowledge-level concepts (such as actor, goal, and the dependency between actors) with a particular focus on requirements analysis. This paper presents a pattern language for guiding developers, especially those without previous Tropos experience, through the various design challenges faced when using Tropos. The patterns format allows us to motivate the modelling constructs, justify each of the development stages, and address specific modelling problems. These patterns are inter-linked in such a way that developers can navigate from higher-level to lower-level patterns as they apply the Tropos methodology. The paper has two goals: to motivate the use of agent-oriented methodologies such as Tropos to a wider set of developers, and to provide guidance for the different development activities of the Tropos methodology. Specifically, we focus on the development stages, models, and diagrams of Tropos. The patterns in this paper cover the early and late requirements analysis stages.

Issues related to large scale systems made of autonomous components encompass among independently developed software and to changing environmental conditions. Formal specifications are traditionally used at design time for software engineering tasks. However, recently, several attempts of using formal specifications at run-time have been realised that let envisage a future use of formal specifications at run-time that will enhance interoperability and adaptability of autonomous components.

This paper intends to highlight the potentialities of the use of formal specifications at run-time as a support for the correct execution of such components. This paper reviews and discusses the use of formal specifications at run-time from different perspectives: software engineering, run-time code evolution, adaptive middleware, trust and security, or business applications. It highlights the potentialities of the use of formal specifications at run-time as a support for interoperability and adaptability of interacting autonomous components. It identifies as well application domains and open issues related to the combination of specifications and code in the framework of large scale systems.

In order to construct and deploy large-scale multi-agent systems, we must address one of the fundamental issues of distributed systems, the possibility of partial failures. This means that fault-tolerance is an inevitable issue for large-scale multi-agent systems. In this paper, we discuss the issues and propose an approach for supporting fault-tolerance of multi-agent systems. The starting idea is the application of replication strategies to agents, the most critical agents being replicated to prevent failures. As criticality of agents may evolve during the course of computation and problem solving, and as resources are bounded, we need to dynamically and automatically adapt the number of replicas of agents, in order to maximize their reliability and availability. We will describe our approach and related mechanisms for evaluating the criticality of a given agent (based on application-level semantic information, e.g. interdependences, and also system-level statistical information, e.g., communication load) and for deciding what strategy to apply (e.g., active or passive replication) and how to parameterize it (e.g., number of replicas). We also will report on experiments conducted with our prototype architecture (named DimaX).