Intra-Role Coordination Using Channeled Multicast

We propose group communication for agent coordination within "active rooms" and other pervasive computing scenarios featuring strict real-time requirements, inherently unreliable communication, and a large but continuously changing set of context-aware autonomous systems. Messages are exchanged over \emph{multicast channels}, which may remind of chat rooms where everybody hears everything being told. The issues that have to be faced (e.g., changing users' preferences and locations; performance constraints; redundancies of sensors, actuators, and services; evolving sources of information; the continuous joining and leaving of agents on mobile devices) require the ability of dynamically selecting the "best" agents for providing a service in a given context. Our approach is based on the idea of \emph{implicit organization}, which refers to the set of all agents willing to play a given role on a given channel; an implicit organization is a special form of team with no explicit formation phase and a single role involved. No middle agent is required by an implicity organization; instead, a set of protocols, designed for unreliable group communication, are used for two purposes: first, to negotiate a coordination policy; second, for actual team coordination. Preconditions and effects of these protocols are formalized by means of the joint intention theory (JIT). We sketch a general computational model for an agent participating to an implicit organization