Abstract: Observation is a fundamental interaction pattern in today's computerbased systems. Adopting observation as the main modelling criterion, computer-based systems can be represented as composed by three class of entities: observers, observables (or sources), and coordinators, that is, the entities managing the observer/source interaction. ents and agent societies are fundamental abstractions in modelling today's complex systems. When exploiting observation in the context of agent-based systems, the most natural interpretation for agents is to see them as either observers or coordinators. However, their situatedness and autonomy, their peculiar perception and representation of the environment, and their typical ability to infer new knowledge