Mobile Objects and Agents (MOA)

Abstract

This paper describes the design and implementation of the Mobile Objects and Agents (MOA) project at the Open Group Research Institute. MOA was designed to support migration, communication and control of agents. It was implemented on top of the Java Virtual Machine, without any modifications to it. The initial project goals were to support communication across agent migration, as a means for collaborative work; and to provide extensive resource control, as a basic support for countering denial of service attacks. In the course of the project we added two further goals: compliance with the Java Beans component model which provides for additional configurability and customization of agent system and agent applications; and interoperability which allows cooperation with other agent systems.This paper analyzes the architecture of MOA, in particular the support for mobility, naming and locating, communication, and resource management. Object and component models of MOA are discussed and some implementation details described. We summarize the lessons learned while developing and implementing MOA and compare it to related work. IntroductionMobility has always attracted researchers in computer science. This interest spans from general observations, such as "if it weren't for mobility, we would still be trees" [10], and the analogies with the real world "migrating birds and nomadic tribes moving due to the lack of resources", to purely technical reasons, such as improving locality of reference and difference between local and remote semantics.One of the first incarnations of software mobile entities. is worms [30], which could spread across nodes and arbitrarily clone. Unrestricted implementations of worms and viruses have received negative connotations, due to security breaches and denial of service attacks [13].The next generation of mobile entities, known as process migration, were implemented at the operating sysThis work was supported in part by the Advanced Research Projects Agency and the Rome Laboratory of the Air Force Materiel Command. tem (OS) level. There were many implementations of process and object migration [3,12,19,31], but none has achieved wide acceptance. Due to inherent complexity, it was hard to introduce process migration without impacting the stability and robustness of the underlying OS.Mobile objects and agents have attracted significant attention recently. In addition to mobile code (such as applets), agents consist of data and non-transient system state that can travel between the nodes in a distributed system (intranet or Internet). Compared to mobile objects, mobile agents also represent someone; they can perform autonomous actions on behalf of a user or another agent. This paper describes the Mobile Objects and Agents (MOA) project at the Open Group Research Institute. The obvious question is why yet another mobile agent system? There were a few reasons. None of the existing systems at the time of starting the project were mature enough to be used as a starting point for our wor...

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