Agent-Based Software Development: Agent Architectures

Although much of the value of the agent paradigm relates to the ways in which multiple agents come together to achieve complex tasks, the starting point of agent-based computing comprises the individual agents themselves.

There are two key reasons why agent architectures are important. The first is that we want to both predict and explain the behavior of an agent system based on its current state and that of the environment. The second is concerned with providing a methodology or blueprint of how to go about building real agent systems

We identify four agent architecture categories and review key examples we consider to be representative of each.

Typically, single agent architectures fall into one of three categories based on their architectures [1], as follows:

Reactive agent systems act by means of stimulus-response rules and do not symbolically represent their environment.

Deliberative agent systems symbolically model their environment and manipulate these symbols in order to act.

Hybrid agent systems can act both deliberatively and reactively.


Single-agent architectures result from what is referred to as the microlevel design perspective where the focus is on the individual agent. The macrolevel design perspective, on the other hand, describes the stance taken when dealing with the social or global dimensions of a distributed agent system. Such systems are designed at a holistic level as well as at the microlevel of individual agents. In particular, consideration of the macrolevel of agent design is used in the construction of distributed agent systems. In order to introduce the basic issues involved in constructing distributed intelligent systems, in this chapter we focus on perhaps the best-known technique for dynamically managing task allocation in a distributed system, the contract net protocol. We also outline the more recent Agentis framework for building interactive multiagent applications, which is based upon an agent interaction model whose central elements are services and tasks. Key to the operation of the Agentis system is the set of protocols that permits reliable concurrent-request and provision of services and tasks from and to agents, based on an underlying asynchronous point-to-point messaging infrastructure