Agents: Mobility And Communication

This paper presents IMAP, a hybrid agent platform composed of several cooperating intelligent agents and mobile agents. IMAP is implemented in Java and Prolog. Java is used to implement the framework of the system, and in particular for supporting the communication between agents and mobility of agent, while Prolog is used to implement both adduction and derivation mechanisms. IMAP intends to independently employ the underlying derivation/adduction and mobility mechanism. In IMAP, intelligent agent and mobile agent can not only fully exploit individual virtue, but also cooperate to perform a task under a uniform platform. Intelligent agents in IMAP are equipped with hypothetical reasoning capabilities, performed by means of adduction: if the knowledge available to an agent is insufficient to solve a query, the agent could adduce new hypotheses. Each intelligent agent can accept queries from mobile agents by means of the interface module, each query is passed to the reasoning module of intelligent agent which performs a derivation and adduction in order to get an answer for mobile agent. IMAP also provides mobile agents a flexible and efficient coordination mechanism and a reliable migration mechanism, and supports persistence of agent state and agent security. Mobile agent's coordination mechanism exploits the advantages of the XML language and Linda-like coordination. This programmable Linda-like coordination mechanism suits the mobility and openness of the Internet application, XML standard for Internet data representation may guarantee a high-degree of interoperability between heterogeneous environments. The design and implementation key technologies of IMAP are described in this paper. An Internet based auction application example shows the suitability and the effectiveness of the IMAP, and its performance evaluation is also made. Finally, some conclusions and remarks are given.

Intelligent mobile agents are sent between routers to carry out a set of required tasks. Mobile agents can carry algorithms and information to various routers they visit. Critical information that all mobile agents should carry includes: timer, navigation algorithm, network information, stability of the network, and load traffic of the network. By clustering intelligent mobile agents, It is possible to minimize the cost of time for each agent to travel to its required routers and the number of intelligent mobile agents. Each router has certain capability and hence an only process certain requests of each intelligent agent. The problem is to group the intelligent mobile agent into a number of clusters such 1h.t that each cluster has similarity in responding to a group of routers. This can significantly decrease the demand imposed upon a network for a set of required task be he performed. In this paper, we present the problem of multiple criteria clustering of intelligent mobile agents where the decision is to cluster mobile agents such that a group of similar intelligent mobile agents will visit a group of similar routers. This grouping will decrease the total number of visits and the total number of agents, decreasing demand on the network.

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The flexibility offered by mobile agents is quite noticeable in distributed computing environments. However, the greater flexibility of the mobile agent paradigm compared to the client/server computing paradigm comes at an additional threats since agent systems are prone to failures originating from bad communication, security attacks, agent server crashes, system resources unavailability, network congestion, or even deadlock situations. In such events, mobile agents either get lost or damaged (partially or totally) during execution. In this paper, we propose parallel checkpointing approach based on the use of antecedence graphs for providing fault tolerance in mobile agent systems. During normal computation message transmission, the dependency information among mobile agents is recorded in the form of antecedence graphs by participating mobile agents of mobile agent group. When a checkpointing procedure begins, the initiator concurrently informs relevant mobile agents, which minimizes the identifying time. The proposed scheme utilizes the checkpointed information for fault tolerance which is stored in form of antecedence graphs. In case of failures, using checkpointed information, the antecedence graphs and message logs are regenerated for recovery and then normal operation continued. Moreover, compared with the existing schemes, our algorithm involves the minimum number of mobile agents during the identifying and checkpoiting procedure, which leads to the improvement of the system performance. In addition, the proposed algorithm is a domino-free checkpointing algorithm, which is especially desirable for mobile agent systems. Quantitative analysis and experimental simulation show that our algorithm outperforms other coordinated checkpointing schemes in terms of the identifying time and the number of blocked mobile agents and then can provide a better system performance. The main contribution of the proposed checkpointing scheme is the enhancement of graph-based approach in terms of considerable improvement by reducing message overhead, execution, and recovery times.

Over the last couple of years we have been working on the development of mobile agents systems and their application to the areas of telecommunications and network management. This work has produced positive results: a competitive mobile agent platform was built, the run-time benefits of mobile agents were proved, and our industrial partners have developed practical applications that are being integrated into commercial products. However, despite the positive results, we feel that mobile agent technology is still not ready to enter the path of mainstream software development. In our perspective, one of the main reasons for this situation arises from the traditional approach to mobile agent technology. This approach, based on the familiar concept of the mobile-agent distributed platform as an extension of the operating system, focuses too much on the mobile agents and associated issues (mobility, agent lifecycle, security, coordination, etc.) and provides poor support for the development of applications where mobile agents are just one of several available technologies. Learning from past experience, we are now working on a new approach where the focus is brought back to the applications and mobile agents become just one the tools available to develop distributed systems. This provides a much lighter framework for application-based mobile agent systems. This paper presents the lessons learned from our previous project and discusses the new concept we are developing: application-centric mobile agent systems.

Software agents are currently considered as a promising paradigm for many distributed applications. Basic features of such agents include autonomy, goal-oriented behaviour, ability to learn and ability to communicate with other agents (interoperability) for problem solving. These features are mainly considered in intelligent agents research community. However, there is another agent feature — mobility — which refers to agents ability to migrate from one host to another and it is mostly considered in mobile agents research community. In spite of mutual interest of the above-mentioned communities in integrating their work most of agent-based systems are still divided by their affiliation either to intelligent or mobile agents communities. In this paper we present our solution to incorporating mobility issues into agent interoperability framework. In particular, we propose a scripting language, which allows expressing both interoperability and mobility constructs. The language can be used for description of agent behaviour and serves as an input to agent machinery component. The proposed language is a result of combining two earlier developed languages and systems Agora and ITAG where, correspondingly, agent interoperability and mobility were implemented. Both systems are compliant to FIPA and MASIF proposals and present a level of abstraction where FIPA and MASIF concepts are utilized.

The security problem of mobile agent is important for applications using mobile agent technology. In this paper, we analyzed the security problems of mobile agent system exposed in opening environment and proposed a method to improve the authentication and credentials management in mobile agent environment. In our design, the trusted computing platform is used as the basic platform to running mobile agent systems, and the trusted platform module will used to help the authentication and credentials management. We also gave a model system for building trusted mobile agent system. In this system, the security of mobile agent is improved by using trusted computing platform which is linked with upper layer applications through the trusted software stack. Then, trusted services for mobile agent, including authentication, credential management and key storage, are supported.

In wireless sensor networks, the mobile agent technology is used in data transmission from one cluster to another cluster. The Optimization of mobile agent in the routing within the clustering algorithm for wireless sensor networks to further reduce the amount of data transfer. the main objectives of wireless sensor network design is to improve the energy efficiency & effective utilization of sensor nodes to prolong the lifespan of a wireless network .This paper presents an effective clustering algorithm, which is an extension to the LEACH routing algorithm., this algorithm fully utilizes the location information of network nodes in routing to reduce the routing cost. Through a clustering approach of intelligent mobile agents, it is possible to reduce the cost of time for each individual agent, here the problem of Multiple Clustering of Mobile Agents (MCCMA) where the decision is to cluster mobile agents such that a group of similar intelligent mobile agents will visit a group of similar sensor nodes are compare with location based clustering algorithm of wsn. both of Simulation results indicate that these algorithm & approach of mobile agent & wireless sensor network Nodes can have balance nodes' energy consumption and prolong the network's life span. It also has good extensibility & stability

Mobile agents can provide many benefits to the development of distributed applications. But the mobile agent system will face some security threat since it will run in an opening network environment. In this paper, we analyzed the security threats in mobile agent system and provided a method to build the trusted connect between entities in mobile agent environment. This method uses the trusted platform module in trusted computing platform as the trusted base. When a mobile agent wants to migrate to another platform, it should use a trusted connect between the source host and the goal host. The agent and agent platform can trust with each other. This method will be helpful to build a trusted computing environment for the mobile agent system.

Detecting and resolving deadlocks in mobile agent systems

Mobile agents are processes that may be dispatched from a source computer and be transported to remote servers for execution. In any mobile agent system, the ability to communicate with agents in real-time is essential for retrieving any data or information that they have collected, and for supporting coordination and cooperation among them. Communication with a mobile agent requires the ability to track it. In the thesis, we propose several distributed mechanisms for tracking (or locating) mobile agents. We first propose a method based on distributed hashing table (DHT) to locate mobile agents efficiently in a large-scale network. The idea is to treat mobile agents and hosts similarly to the way peers are treated in a peer-to-peer system, and to implement a lookup protocol that is based on that principle, while taking care of the mobile nature of the agents. We then introduce a new locating mechanism. Our technique is based on appropriate delays that the mobile agents must perform while moving on the network so to facilitate its tracking, should it be needed. The searching agent computes a particular searching path that will guarantee the tracking within one traversal of the network. We indicate various strategies, and we perform experiments for computing the searching path and for comparing their performances in synchronous and asynchronous settings, in arbitrary and specific topologies.

Mobile agent systems provide new perspectives for distributed e-commerce applications. These applications may present specific restrictions, making mobile agent systems a feasible solution. Even so, mobile agents present some security related problems. An important one is resource access control. The ability for mobile agents to provide a simple, scalable, flexible, and secure access control system is a key point for the widespread adoption of mobile agents. In this paper we propose a mechanism to safely assign roles to mobile agents and an access control method based on Role-based Access Control (RBAC). The access control method provides a simple, lightweight and distributed model for mobile agent applications. It is proposed as an extension of the MARISM-A (An Architecture for Mobile Agents with Recursive Itineraries and Secure Migration) project, a secure mobile agent platform.

Providing integrity of execution is considered as the most challenging problem in Mobile Agent System (MAs). Mobile agent watermarking (MAW) is a technique that attempts to provide integrity of execution to a mobile agent. We discuss the attacks against MAW technique and how the security properties for MAs data integrity are fulfilled. We try to model the behavior of a malicious host by launching a series of passive attacks against mobile agent and then see to what extent the security properties for mobile agent can be achieved. The experimental results suggest that MAW framework can be used to protect the computations results of mobile agents

Mobile agents are software entities that consist of code, data and state, and that can migrate autonomously from host to host executing their code. Security issues restrict the use of code mobility despite its benefits. The protection of mobile agents from the attacks of malicious hosts is considered by far the most difficult security problem to solve in mobile agent systems. Using a Trusted Third Party in the mobile agent system can aid to solve this problem. The Host Revocation Authority [2] is a TTP that controls which hosts acted maliciously in the past, and for this reason they have been revoked. Each agent sender consults the HoRA before sending an agent in order to remove from the agent’s itinerary all the malicious hosts. Accordingly, the revoked hosts will not receive mobile agents any more. This paper presents two new protocols that can be used to revoke malicious hosts.

Although the mobile agent paradigm provides great potential advantages ever traditional approaches in distributed computing applications, there are still several issues to be addressed before the technology can be widely accepted. The performance of the communication protocol is one of the critical issues in mobile agent systems. A practical communication protocol for mobile agents must satisfy three basic requirements: location transparency, reliability and efficiency. Although many communication protocols have been proposed for mobile agent systems and most of them are location transparent, these protocols usually compromise some aspects of reliability and efficiency. In this research we develop a communication scheme for efficient location tracking of agents and reliable message delivery in mobile agent systems by using a proxy-based scheme. The location update and message delivery protocols are developed and shown to be reliable even when agents migrate during message delivery. A simulation model is developed to estimate the performance relative to a (nonproxy-based) home-server protocol. Sensitivity analysis is used to reveal the important circumstances (domain/agent dimensions and exogenous demand/movement characteristics) for efficient communication performance.