Like middle-men in physical commerce, middle-agents support the flow of information in electronic commerce, assisting in locating and connecting the ultimate information provider with the ultimate information requester. Many different types of middle agents will be useful in realistic, large, distributed, open multi-agent problem solving systems. These include matchmakers or yellow page agents that process advertisements, blackboard agents that collect requests, and brokers that process both. The behaviors of each type of middle-agent have certain performance characteristics-- privacy, robustness, and adaptiveness-- qualities that are related to characteristics of the external environment and to the agents themselves. For example, while brokered systems are more vulnerable to certain failures, they are also able to cope more quickly with a rapidly fluctuating agent workforce and meet certain privacy considerations.

We have identified a variety of middle agent types based on privacy considerations of service providers' capabilities and requesters' preferences. Click the following icon to view a table displaying the different middle agent types we have identified: