We study the gathering problem requiring a team of mobile agents to gather at a single node in arbitrary networks. The team consists of k agents with unique identifiers (IDs), and f of them are weakly Byzantine agents, which behave arbitrarily except falsifying their identifiers. The agents move in synchronous rounds and cannot leave any information on nodes. If the number of nodes n is given to agents, the existing fastest algorithm tolerates any number of weakly Byzantine agents and achieves gathering with simultaneous termination in O(n4·|Λgood|·X(n)) rounds, where |Λgood| is the length of the maximum ID of non-Byzantine agents and X(n) is the number of rounds required to explore any network composed of n nodes. In this paper, we ask the question of whether we can reduce the time complexity if we have a strong team, i.e., a team with a few Byzantine agents, because not so many agents are subject to faults in practice. We give a positive answer to this question by proposing two algorithms in the case where at least 4f2+9f+4 agents exist. Both the algorithms assume that the upper bound N of n is given to agents. The first algorithm achieves gathering with non-simultaneous termination in O((f+|&Lambdagood|)·X(N)) rounds. The second algorithm achieves gathering with simultaneous termination in O((f+|&Lambdaall|)·X(N)) rounds, where |&Lambdaall| is the length of the maximum ID of all agents. The second algorithm significantly reduces the time complexity compared to the existing one if n is given to agents and |&Lambdaall|=O(|&Lambdagood|) holds.

A vehicular ad hoc network (VANET) consists of vehicles (mobile nodes) and road side units which are equipped with the wireless devices such as wireless LANs. Mobile nodes exchange information messages with each other so that VANETs are configured in a self-organized manner. As one of network service scenarios in VANETs, there is a network service to provide the parking spaces in the city central to vehicles (mobile nodes). In this scenario, the road side units (source nodes) which are deployed at the parking spaces periodically disseminate the number of available parking spaces to mobile nodes. Therefore, in this paper, we propose a mobile agent-based information dissemination scheme using location information of mobile nodes and source nodes in the VANET environment. In addition, we conduct simulation experiments in the VANET environment to evaluate the proposed mobile agent-based information dissemination scheme. We confirmed that it could disseminate information messages with lower overhead because mobile agents migrate among mobile nodes by using the location information.

The success of peer-to-peer overlay networks depends on cooperation among participating peers. In this paper, we investigate the degree of cooperation among individual peers required to induce globally favorable properties in an overlay network. Specifically, we consider a resource pricing problem in a market-oriented overlay network where participating peers sell own resources (e.g., CPU cycles) to earn energy which represents some money or rewards in the network. In the resource pricing model presented in this paper, each peer sets the price for own resource based on the degree of cooperation; non-cooperative peers attempt to maximize their own energy gains, while cooperative peers maximize the sum of own and neighbors' energy gains. Simulation results are presented to demonstrate that the network topology is an important factor influencing the minimum degree of cooperation required to increase the network-wide global energy gain.

Genetic Algorithms (GA) provide an attractive approach to solving the challenging problem of dynamic routing and wavelength assignment (RWA) in optical Wavelength Division Multiplexing (WDM) networks, because they usually achieve a significantly low blocking probability. Available GA-based dynamic RWA algorithms were designed mainly for WDM networks with a wavelength continuity constraint, and they cannot be applied directly to WDM networks with wavelength conversion capability. Furthermore, the available GA-based dynamic RWA algorithms suffer from the problem of requiring a very time consuming process to generate the first population of routes for a request, which may results in a significantly large delay in path setup. In this paper, we study the dynamic RWA problem in WDM networks with sparse wavelength conversion and propose a novel hybrid algorithm for it based on the combination of mobile agents technique and GA. By keeping a suitable number of mobile agents in the network to cooperatively explore the network states and continuously update the routing tables, the new hybrid algorithm can promptly determine the first population of routes for a new request based on the routing table of its source node, without requiring the time consuming process associated with current GA-based dynamic RWA algorithms. To achieve a good load balance in WDM networks with sparse wavelength conversion, we adopt in our hybrid algorithm a new reproduction scheme and a new fitness function that simultaneously takes into account the path length, number of free wavelengths, and wavelength conversion capability in route selection. Our new hybrid algorithm achieves a better load balance and results in a significantly lower blocking probability than does the Fixed-Alternate routing algorithm, both for optical networks with sparse and full-range wavelength converters and for optical networks with sparse and limited-range wavelength converters. This was verified by an extensive simulation study on the ns-2 network simulator and two typical network topologies. The ability to guarantee both a low blocking probability and a small setup delay makes the new hybrid dynamic RWA algorithm very attractive for current optical circuit switching networks and also for the next generation optical burst switching networks.

The use of peer-to-peer (P2P) file sharing networks such as Gnutella is proliferating on the Internet, but due to the broadcast nature of the protocols, the use of such applications are bandwidth consuming. This characteristic makes P2P file sharing unsuitable for mobile devices because they have severe bandwidth and power constraints. This paper proposes the MAP2P architecture that uses mobile agents to participate in the Gnutella network on behalf of mobile devices. The aim is to reduce the amount of traffic, and hence the power consumption, for the mobile devices. Moreover, our architecture provides support for device mobility at the application layer. The viability of our architecture is illustrated through our traffic and energy analyses with experiments using our demonstration implementation.

We formally define the mobile agent allocation problem from a system-wide viewpoint and then prove that it is strongly NP-complete even if each agent communicates only with two agents. This is the first formal definition for scheduling mobile agents from the viewpoint of load balancing, which enables us to discuss its properties on a rigorous basis. The problem is recognized as preemptive scheduling with independent tasks that require mutual communication. The result implies that almost all subproblems of mobile agent allocation, which require mutual communication of agents, are strongly NP-complete.

Autonomous Information Service System is a proposition made to cope with the continuously changing conditions of service provision and utilization in current information systems. The faded information field (FIF), sustained by push/pull mobile agent technology, is such a distributed architecture that brings high-assurance of the system through a balanced selective replication of the information. When the demand changes, the information environment is restructured so that the same response time to services for all unspecified users can be achieved whatever the demand volume. However, once the structure is fixed, dispatching the randomly incoming requests on the FIF is still required to guarantee the same quality of service. Our goal is to warrant the autonomous dispatching of the pull mobile agents to adjust the continuously evolving arrival distribution of the demand to the current information environment. In this paper, we explain the concepts and realization of autonomous navigation under the goal of an autonomous load balancing of the pull mobile agent volume in the FIF structure. The appropriateness of this method for FIF environments has been shown by simulation.

The Internet is a heterogeneous and rapidly evolving environment. New information services have been added, modified, and diversified, while legacy services have been abandoned. Users' requirements for services are also changing very quickly. It is becoming very difficult to find required information services from extremely huge amount of information in the Internet. It is necessary to design information service system, which can meet user's heterogeneous requirements for services, adaptability of services to cope with ever-changing situation and to provide assurance. Faded information field architecture and Push/Pull Mobile Agent (MA) technologies are proposed as basic components of autonomous information service system to achieve these goals. The system is proposed from users' and providers' point of view, therefore we present a technique for balancing users' and providers' communication cost based on `through rate' for faded information field realization. On the basis of this technique, autonomous information allocation algorithm is proposed, in which each node may determine information amount based on push/pull cost. The effectiveness of the proposed algorithm is shown through simulation.

The Mobile Agent technology helps in the development of applications in open, distributed and heterogeneous environments such as the Internet and the Web, but it has to answer to the requirements of security and interoperability to achieve wide acceptance. The paper focuses on security and interoperability, and describes a Secure and Open Mobile Agent (SOMA) programming environment where both requirements are main design objectives. On the one hand, SOMA is based on a thorough security model and provides a wide range of mechanisms and tools to build and enforce flexible security policies. On the other hand, the SOMA framework permits to interoperate with different application components designed with different programming styles. SOMA grants interoperability by closely considering compliance with the OMG CORBA and MASIF standards. SOMA has already shown the feasibility and effectiveness of the approach for the development of flexible and adaptive applications in several areas, particularly in network and systems management.

This paper describes a transaction model for open environments based on mobile agents. Mobile agent-based transactions combine mobility and the execution of control flows with transactional semantics. The model presented represents an approach for providing reliability and correctness of the execution of distributed activities, which fulfills important requirements of applications in Open Environments. The presented transaction model is based on a protocol for providing fault tolerance when executing mobile agent-based activities. This protocol is outlined in this paper. With this protocol, if an agent executing an activity at an agency (logical "place" in a distributed agent environment) becomes unreachable for a long time, the execution of the activity can be recovered and continue at another agency. The fault tolerance approach supports "multi-agent activities," i. e. , activities where some of its parts are spawned to execute and migrate asynchronously in relation to other parts. The described transaction model, called the basic (agent-based) transaction model, is an open nested transaction model. By being based on the presented fault tolerance mechanism, subtransactions can be executed asynchronously in relation to their parent transactions and agent-based transactions can explore alternatives in the event of agent unavailability. The model fulfills requirements for supporting the autonomy of organizations in a distributed agent environment.