The spider model of agents

This thesis rst identi es some of the major problems in the existing mobile agent theo-ries and software mobile-agent systems. The identi ed problems are the improper mixture of agent mobility and communication, the confusion between physical mobility and virtual mobility, the poor implementability of theoretical models, and the poor understandability and security weakness of software systems. Then the thesis proposes the Spider Model of Agents to deal with these problems. A formal de nition of the model is constructed in a restrictive form of mobile ambients. A prototype system conforming to the formal model is designed and implemented in Java. The experience from applications of the model sug-gests that clear separation of mobility and communication simpli es mobile-agent system designs, make it easier to understand and reason about systems, and gives better security. An implementable formalism for mobile-agent systems also gives a tool to describe and understand systems, and verify system designs. The improvements the model suggests are bene cial to move the mobile agent technology closer to practical use. Keywords: mobile agent, agent model, reasoning, Java.