Designing Multi-agent Systems around an Extensible Communication Abstraction

Abstract

What is relevant for the effectiveness of a multi-agent system is the interaction between agents, rather than their peculiar internal model. The design of a single agent architecture should then concentrate on agent observable behaviour and on its interface towards the outside. Moreover, a multi-agent architecture should be designed around the choice of a suitable coordination model, accounting for all the aspects of agent interaction. Accordingly, the effective design of a multi-agent architecture should focus on the role and properties of the coordination media (the communication abstractions) within the coordination model, instead of the coordination entities (the agents).

The main aim of this paper is to show how a multi-agent system may benefit by a coordination model whose flexibility and expressive power lies in the extensibility of the coordination medium. Extensibility can result from the embodiment of computational properties typically in charge of the agents into the communication abstraction.

As an example, we show how a shared communication device à la Linda works as the core of a flexible coordination architecture in the Lindabased $\mathcal{A}\mathcal{C}\mathcal{L}\mathcal{T}$ coordination model. $\mathcal{A}\mathcal{C}\mathcal{L}\mathcal{T}$ tuple spaces are enhanced so as to be reactive to communication events, rather than to communication state changes only. So, $\mathcal{A}\mathcal{C}\mathcal{L}\mathcal{T}$ tuple spaces are programmable. Reactions to communication events can be defined through a logic-based specification language, and have the semantics of asynchronous, mutuallyindependent atomic transactions. By defining different observable behaviours for $\mathcal{A}\mathcal{C}\mathcal{L}\mathcal{T}$ tuple spaces through reaction programming, a multiagent architecture can exploit a number of different agent coordination policies without affecting the single agent behaviour.