Position summary: separating mobility from mobile agents

Abstract

The reasons for using mobile agents are well-known: moving computation to data to avoid transferring large amounts of data; supporting disconnected operation by, for example, moving a computation to a network that has better connectivity; supporting autonomous distributed computation by, for example, deploying a personalized filter near a real-time data source. Many mobile agent systems have been constructed and are in the public domain. But, despite these well-known advantages and widely available software, mobile agents are not yet being used as a common programming abstraction. We have been working since 1993, under the name of TACOMA, on operating system support and application of mobile agents. We have addressed issues including fault-tolerance, security, efficiency, and runtime structures and services. We have built a series of mobile agent middleware systems and evaluated them by building realistic and deployed applications. We have found that mobile agents are especially useful for large-scale systems configuration and deployment, system and service extensibility, and distributed application self-management. The programming model TACOMA supports has changed over these years to reflect our experience with writing real applications. Like other mobile agent systems, TACOMA started with a programming model that resembled the characterization given above of mobile agents being processes with explicit control over where they execute. We call this the traditional model of mobile agents.