Yasuyuki Tahara

IOM/T: an interaction description language for multi-agent systems

A multi-agent system is a useful approach for the complex systems. One of the important concepts of multi-agent systems is cooperativeness, or interactions. However, existing languages for implementing interactions lack expressiveness. This causes gaps between design and implementation. This paper analyzes language functionalities for implementing interactions. Furthermore, a new interaction description language IOM/T is proposed based on the findings. Interaction would become easy to implement based on design using IOM/T.

Mobile agent security with the IPEditor development tool and the mobile UNITY language

Many people consider that security is one of the biggest problems for practical use of mobile agents that move around the network and do their tasks. In this paper, we assert that this issue can be effectively managed by using IPEditor, the development support tool of mobile multi-agent applications that we have been released, and Mobile UNITY, a formal specification language of mobile agent applications. IPEditor helps developers to design applications with visual supports of agent behaviors. In our method, we translate an IPEditor model to a Mobile UNITY program that is the formal specification of the agent behaviors. In addition, we describe the security requirements by the Mobile UNITY logic notation. Thus we can verify the security requirements by proving that the mobile UNITY program, therefore the IPEditor model, satisfies the mobile UNITY logic notation. We present an example of an electronic catalog (e-catalog) application and illustrate the effectiveness of our proposal.

Behavior descriptions of mobile agents for Web services integration

Web services technology for interoperability, dynamic discovery and integration of distributed components is to be applied in various environments, such as networks of relatively narrow and unstable wireless connections. However, in such environments it is necessary to deal with resource limitation. Our work adopts mobile agent technology in response to this problem and presents a mobile agent framework for Web Services integration. This framework utilizes BPEL (Business Process Execution Language for Web Services) for description of the integration logic, and provides declarative descriptions for physical behaviors (migration and cloning). This facilitates addition or change of physical behaviors according to the environmental conditions while preserving the integration logic. This paper especially focuses on formal definition and discussion of our framework.

Security for mobile agents

In view of the proliferation and expansion of wide-area open networks such as the intranets and extra-nets, agent technology is attracting greater attention. However, as yet there is well-established and widely used method of developing safe and secure agent systems. In this paper, we propose a methodology that supports the step-by-step development of mobile agent systems while ensuring consideration of security issues. This approach results in a robust infrastructure for practical system development, and by supporting calculation of various costs allows efficiency and security tradeoffs to be objectively evaluated.

Bridging the gap between AUML and implementation using IOM/T

Multi-agent systems are attractive means for developing complex software systems. However, multi-agent systems themselves tend to be complex, and certain difficulties exist in developing them. One of the difficulties is the gap between design and implementation especially for interaction protocols. In this paper, we propose a new interaction protocol description language called IOM/T. Interaction protocols described using IOM/T have clear correspondence with AUML sequence diagrams and the description can be consolidated into a single unit of IOM/T code. Then, we show how the process of implementing Java-based agent-platform code from AUML design can be carried out, and how IOM/T effectively bridges the gap between design and implementation.

Agent system development method based on agent patterns

This paper proposes a method of agent system development based on agent patterns that represent typical and recurring structures and behaviors of agents. The agent patterns are classified according to their appropriate architectural levels and the degree of their dependence on specific agent platforms. Our method enables developers to design agent systems efficiently since they can construct complicated system architectures and behaviors by dividing the design process into two architectural levels and applying the appropriate agent patterns. In addition, the higher level designs are independent of specific agent platforms and can be therefore easily reused.

Secure and efficient mobile agent application reuse using patterns

As wide-area open networks like the Internet and intranets grow larger, mobile agent technology is attracting more attention. Mobile agents are units of software that can deal with environmental changes and the various requirements of open networks through features such as autonomy, mobility, intelligence, cooperation, and reactivity. In addition, some people consider the agent technology as a promising solution to the reuse issue because of the aspect of the agents as highly adaptable software components. However, since the usual development methods of secure mobile agent applications are not sufficiently investigated, the technology is not yet widespread. In this paper, we propose a formal framework that supports mobile agent application development and reuse with consideration of the trade-offs between the security issues and the performance issues. In our framework, we design a mobile agent application by building a computational cost model and a security model, and combining patterns so that the combination satisfies the models. Therefore we can develop the application considering the security and the performance trade-offs. Since the models and the patterns are presented according to a formal framework, we can make sure that the pattern combination satisfies the models rigorously. In addition, if the security policy of the new environment is different from the old one in reusing the system in a new organization, we can easily modify and adapt the behavior because the pattern application can be figured out automatically by an algorithm.

Mobile and cooperative compounds of multimedia services

This work proposes a novel model where multimedia contents with their related services (business processes and functions) are packaged together as mobile agents. This is intended to enable content providers both to encapsulate their contents and to provide value-added services, for flexible content editing, delivery, and presentation. In addition, agents encapsulating contents/services can contain other agents in themselves (synthesis of agents). A mobile agent compound integrating multiple contents/services can be thus dynamically formed, in which multiple agents work cooperatively and migrate together as a unit. This paper also describes our proposed MAFEH/WS framework for the model. Agents in the model can be developed by incorporating simple parameter settings for synthesis control into business process descriptions in BPEL4WS.

Pigeon: A Specification Language for Mobile Agent Applications

Recently, research of formal models and specification languages of mobile agents is growing in order to cope with problems in using mobile agents such as security and control of complicated behaviors including migration. Such models and languages require the following features to be widely used in practical applications. The first is customizability to conform to a variety of agent platforms whose features may include various migration and communication modes and various agent architectures. The second is sufficient descriptive power to handle various requirements such as security and safety. However, existing models and languages are not satisfactory in these aspects. In this paper, we propose Pigeon, a specification language for mobile agent applications. We can customize not only the syntax of Pigeonbut also its semantics by representing the semantics in a logical framework called RL/R (reflective rewriting logic) and making the representation changeable. The high descriptive power of Pigeonis realized by the reflection feature of RL/R. We illustrate the practical advantage of Pigeonby applying it to an example of a B2B EC electronic catalog system and comparing other models and languages.

A Formal Model of Active Contents Based on the Ambient Calculus

The recent innovation of telecommunication and networking technology is enabling easy and flexible distribution of digital multimedia contents. However, such rapid progress has brought about various problems on intellectual properties and security. We are investigating a technique to solve the problem called active contents based on hierarchical structures of mobile agents. The agents work as wrappers of contents and can easily manage the policies for contents distribution. In this paper, we give a formal model of active contents in order to establish rigorous foundations for the active contents technique, especially the system of the policy control mechanisms. Using the model, we can verify if the behaviors of the active contents satisfy the given policies or not. An example of the redistribution prohibition policy illustrates how the verification works.