Introduction to Special Issue on Mobile Agents

Abstract

Over the last years, mobility has been one of the most thoroughly researched topics of the agent field. As the technology has evolved and matured, research on mobility is now focusing on subtopics crucial to the long-term success of mobile agents. For this special two-part issue, we have selected seven papers which, collectively, provide in-depth coverage of essential research issues, such as composition, security, resource management, and communication. Five of these papers have appeared, in shorter versions, at the First Joint Symposium of Agent Applications and Systems, and Mobile Agents ’99 [1]. The remaining two papers are published here for the first time. In the context of agent technology, what does the term mobile mean? A mobile agent is not bound to the system where it begins execution. It has the unique ability to transport itself from one system in a network to another system. Created in one execution environment, it can transport its state and code to another execution environment in the network, where it resumes execution. By the term state, we typically mean the attribute values of the agent that help it determine what to do when it resumes execution at its destination. The term code, in an object-oriented context, means the class code necessary for the agent to execute. The ability to travel allows a mobile agent to move to a system that contains an object with which the agent wants to interact, and take advantage of being in the same host or network as the object. Mobility is an orthogonal property of agents—that is, not all agents are mobile. These that do not or cannot move are called stationary agents. A stationary agent executes only on the system where it begins execution. If it needs information that is not on that system, or needs to interact with an agent on a different system, it uses conventional means of communication such as various forms of remote procedure calling and messaging. In (Lange and Oshima 1999) [2] we listed seven reasons for choosing mobile agents in software application development: