One of the main issues in the engineering of multi-agent systems is to give a precise semantics to agent communicative acts, by specifying how agent interactions with the environment affect and are affected by the agent inner status — namely, by the decisions it takes and by its perception of the world.
In this paper, we tackle this problem by modelling agents as observable sources, that is, as proactive and autonomous abstractions manifesting an observable status and dynamics, and allowing external entities to perceive and alter it.
Based on this idea, an abstract language for specifying agents observable behaviour is presented, providing the designer with a tool for precisely characterising the relationship between agents internal aspects and agents collaborative aspects.
We claim that this language can be the basis for a successful engineering methodology for agent-based systems where the concept of observation is taken as a foundational issue.