E. del Val

Combination of self-organization mechanisms to enhance service discovery in open systems

Abstract Decentralized systems have emerged as an alternative to centralized approaches for dealing with dynamic requirements in new business models. These systems should provide mechanisms that contribute to flexibility and facilitate adaptation to changes in the environment. In this paper, we present two self-organization mechanisms for a decentralized service discovery system in order to improve its performance. These mechanisms are based on local actions of agents that only consider local information about queries they forward during the discovery process. The self-organization actions are chosen by each agent individually when the agent considers them to be appropriate. The actions are: remaining in the system, leaving the system, cloning, and changing structural relations with other agents. We have evaluated each self-organization mechanism separately but also the combination of the two as the environmental conditions in the service demand change. The results show that the proposed self-organization mechanisms considerably improve the performance of the service discovery system.

Promoting cooperation in service-oriented MAS through social plasticity and incentives

Highlights? We propose a model to promote cooperation in decentralized service discovery scenarios where agent is situated in a network based on social preferences. ? The model integrates structural changes and the use of incentives to promote and maintain cooperation even in scenarios where there is a large number of non-cooperative agents. ? The model does not rely on third parties to take decisions. Each agent relies on local information generated during the service discovery process to take decisions about its neighbors and its behavior. In distributed environments where entities only have a partial view of the system, cooperation plays a key issue. In the case of decentralized service discovery in open service-oriented multi-agent systems, agents only know about the services they provide and their direct neighbors. Therefore, they need the cooperation of their neighbors in order to locate the required services. However, cooperation is not always present in open and distributed systems. Non-cooperative agents pursuing their own goals could refuse to forward queries from other agents to avoid the cost of this action; therefore, the efficiency of the decentralized service discovery could be seriously damaged. In this paper, we propose the combination of local structural changes and incentives in order to promote cooperation in the service discovery process. The results show that, even in scenarios where the predominant behavior is not collaborative the cooperation emerges.

Self-Organized Service Management in Social Systems

Humans create efficient social structures in a self-organized way. People tend to join groups with other people with similar characteristics. This is call homophily. This paper proposes how homophily can be introduced in Service-Oriented Multiagent Systems to create efficient self-organized structures in which agents are linked to similar agents, where the similarity is based on the set of services that each agent provides and the roles they play. The results show that a greedy method can be used to locate services in the network and that homophily, which links similar services together, can produce a significant improvement in the performance of the search process. A second contribution is the study of the adaptation of the agents to the number and the type of services demanded. The paper shows how, considering just local information and making local decisions to stay or leave the system, the network adapts itself to a known service distribution.

Ensuring Time in Service Composition

Time is an important non-functional parameter to consider in service compositions, especially in environments where a service must be provided before a deadline. This paper presents a framework that deals with service compositions taking into account the service execution time. To enhance this composition it is important to provide service execution times with reliability, bearing in mind the workload and availability of the service.

Self-organization in service discovery in presence of noncooperative agents

Self-organization and cooperation of agents in open societies play an important role in the success of the service discovery process. Self-organization allows agents to deal with dynamic requirements in service demand. Moreover, in distributed environments where service discovery is carried out by agents that only have a partial view of the system, cooperation with neighbors is a key issue in order to locate the required services. However, cooperation is not always present in open agent societies. With this motivation, we present a set of mechanisms that consider self-organization actions and incentives to adapt the structure of the society to the service demand and to promote a cooperative behavior among agents in open societies.

Enhancing Smart-Home Environments using Magentix2

Abstract Multi-agent system paradigm has been envisioned as an appropriate solution for challenges in the area of smart-environments. Specifically, MAS add new capabilities such as adaption, reorganization, learning, coordination, etc. These features allow to deal with open issues in the context of smart-homes such as multi-occupancy, activity tracking or profiling activities and behaviors from multiple residents. In this paper, we present Magentix2 as a suitable MAS platform for the development of dynamic smart environments. Specifically, the use of Magentix2 ( http://gti-ia.upv.es/sma/tools/magentix2/index.php ) facilitates the management of the multiple occupancy in smart living spaces. Normative virtual organizations provide the possibility of defining a set of norms and organizational roles that facilitate the regulation and control of the actions that can be carried out by internal and external agents depending on their profile. Moreover, Magentix2 provides a tracing service to keep track of activities carried out in the system. We illustrate the applicability and benefits of Magentix2 in a set of scenarios in the context of smart-homes.

A Multi-agent Framework for the Analysis of Users Behavior over Time in On-Line Social Networks

The number of people using on-line social networks as a new way of communication is continually increasing. The messages that a user writes in these networks and his/her interactions with other users leave a digital trace that is recorded. In order to understand what is going on in these virtual environments, it is necessary to use systems that collect, process, and analyze the information generated. Currently, there are tools that analyze all the information related to an on-line event once the event finished or on a specific point of time (i.e., without considering the evolution of users’ actions during the event). In this article, we present a multi-agent system (MAS) that deals with the analysis of the evolution of users’ interactions in events on on-line social networks during a period of time. The system offers a complete vision of what is happening in an event. We evaluated its functionality through the analysis of a set of events on Twitter.

Using Magentix2 in Smart-Home Environments

In this paper, we present the application of a multi-agent platform Magentix2 for the development of MAS in smart-homes. Specificallly, the use of Magentix2 (http://gti-ia.upv.es/sma/tools/magentix2/index.php) platform facilitates the management of the multiple occupancy in smart living spaces. Virtual organizations provide the possibility of defining a set of norms and roles that facilitate the regulation and control of the actions that can be carried out by the internal and external agents depending on their profile. We illustrate the applicability of our proposal with a set of scenarios.

STRATEGIES FOR COOPERATION EMERGENCE IN DISTRIBUTED SERVICE DISCOVERY

In distributed environments where entities only have a partial view of the system, cooperation is a key issue. In the case of decentralized service discovery in open agent societies, agents only know about the services they provide and who their direct neighbors are. Therefore, they need the cooperation of their neighbors in order to locate the required services. However, cooperation is not always present in open systems. Noncooperative agents pursuing their own goals could refuse to forward queries from other agents to avoid the cost of this action; therefore, the efficiency of the decentralized service discovery could be seriously damaged. In this article, we propose the combination of incentives and local structural changes in order to promote cooperation in the service discovery process. The results show that, even in scenarios where the predominant behavior is not collaborative, cooperation emerges.

Decentralized Service Management Based on Homophily for Self-Adaptive SOMAS

Humans create efficient social structures in a self-organized way based on a feature called homophily. This paper proposes the use of homophily in Service-Oriented Multiagent Systems to create efficient self-organized structures and provide a decentralized service management.