Distributed policy resolution through negotiation in ubiquitous computing environments

Ensuring spontaneous ad hoc interoperation in decentralized ubiquitous computing environments is challenging, because of heterogeneous resources and divergent policies. Centralized cross-domain service access agreements can be made with a priori knowledge of the interacting entities´ policies, but privacy concerns make this approach impractical. Environments should not be too rigid nor too open in their interactions, and should support varying contexts and scenarios. We describe the modeling, design, and implementation of a general purpose negotiation protocol for cross-domain service access agreements between entities that do not share trust agreements or application level protocols. This protocol resolves the constraints and needs of the participants, described in the form of declarative logical policies, in a fully distributed manner, avoiding the need for a third party. We describe how we tested the system and show how negotiation performance was evaluated against an optimal case computed by a centralized oracle.