A Multi-agent Approach for Routing on Vehicular Ad-Hoc Networks

AbstractVehicular Ad-Hoc Network is a special form of mobile ad -hoc networks (MANETs) which is a vehicle to vehicle and vehicle roadside wireless communication network. VANET is a new standard that integrates Wi-Fi, Bluetooth and other mobile connectivity protocols. The essential requirement of VANET is that it should be able to communicate in any environment irrespective of traffic densities and vehicle locations. Vehicular communications are made in fluctuating environment and should work both in urban and rural areas. Considering the large number of nodes participating in these networks and their high mobility, debates still exist about the feasibility of routing protocols. Analyzes of traditional routing protocols for MANETs demonstrated that their performance is poor in VANETs. The main problem with these protocols in VANETs environments is their route instability. Consequently, many packets are dropped and the overhead due to route repairs or failure notifications increases significantly, leading to low delivery ratios and high transmission delays. This paper introduces a multi-agent system approach to solve the problems mentioned above and improve Vehicular ad-hoc network routing

A Multi-Criteria Approach for Web Service Discovery

AbstractWith the growth of Web Services number and with the diversification of their types and qualities, the choice of the service that complies with user preference became a fundamental issue. The task of finding the best Web service is no longer an easy task and may end to unsatisfactory result. To resolve this problem, we adopt in this paper a Web services discovery and selection approach based on user preferences. These preferences are based on a multi-criteria approach that allows clients to assign weights values to the QoS parameters according to their needs. Consequently, the selected services will correspond to the real clients needs. In our application, we have also integrated a mechanism for semantics recommendation. This recommendation serves to guide the client preferences and to refine more the results given by the selection mechanism based on QoS parameters. Unlike other approaches, in our work, we separate between recommendation and discovery mechanism. This will give the client the freedom to choice his own scenario and to gain in terms of processing time. Our approach integrates also geospatial criteria which are of paramount importance in mobile applications

Extending Policy Languages for Expressing the Self-Adaptation of Web Services

With the growing demand on Web Services, self-adaptation in the highly-dynamic environment is becoming a key capability of service-based systems. As a solution for Web services to provide added value and high QoS, combining self-* and policies allows reducing management complexity and effectively drives adaptation. Also, providers must participate in the self-adaptation process as they are aware of the capabilities of their offered services and exceptions that may occur. Despite the important role of service providers, existing approaches did not address this major issue. Thus, the description of self-adaptive Web services must not be limited to functional and QoS data. To address these issues, we extend the WS-Policy framework to represent capabilities and requirements of self-* Web services. We also extend UDDI in order to store and manage service policies, as the current UDDI model does not offer these capabilities. Finally, we propose an ECA-based planning mechanism to specify decision making in the self-adaptation process

The Multi-agent Prey/Predator problem: A Petri net solution

1 CoOperative Objects are a Concurrent Object-Oriented Language using Petri Nets to define the concurrency inside each Object and between Objects. This paper shows how this language may be used with benefits to model Multi-Agent Systems, using as an example the well-known Prey/ Predators game. I. Introduction The most of the time the agent theory is expressed by Modal Logic that is a good specification tool since it eases the description of intentional agents. However, this formalism cannot be easily refined into implementation even if some counter-examples exist (see [Wooldridge 94] for example). This paper proposes another type of formalism based on Petri-Nets and Objects. This formalism, called CoOperative Objects [Sibertin 95] (COO for short), belongs to the class of Concurrent ObjectOriented Languages but it can also be used with benefits to both specify and implement autonomous and concurrent agents. Actually, in one hand COO can be considered as a specification language since ..