In agent-based systems, the performance of middle agents not only relies on the matchmaking algorithms employed by them, but also the architecture that organizes them with suitable organizational structure and coordination mechanism. In this paper, we contribute a framework and develop a couple of middle agents with logical ring organizational structure to match requester agents with service provider agents. The middle agent is of the features of proliferation and self-cancellation according to the sensory input from its environment. The token-based coordination mechanism of middle agents is designed. Two kinds of middle agents, namely, host and duplicate, are designed for promoting the scalability and robustness of agent-based systems. We ...