A Lightweight Coordination Middleware for Mobile Computing

Abstract

This paper presents Limone, a new coordination model that facilitates rapid application development over ad hoc networks consisting of logically mobile agents and physically mobile hosts. Limone assumes an agent-centric perspective on coordination by allowing each agent to define its own acquaintance policy and by limiting all agent-initiated interactions to agents that satisfy the policy. Agents that satisfy this acquaintance policy are stored in an acquaintance list, which is automatically maintained by the system. This asymmetric style of coordination allows each agent to focus on relevant peers. Coordination activities are restricted to tuple spaces owned by agents in the acquaintance list. Limone tailors Linda-like primitives for mobile environments by eliminating remote blocking and complex group operations. It also provides timeouts for all distributed operations and reactions that enable asynchronous communication with agents in the acquaintance list. Finally, Limone minimizes the granularity of atomic operations and the set of assumptions about the environment. In this paper we introduce Limone, explain its key features, and explore its capabilities as a coordination model. A universal remote control implementation using Limone provides a concrete illustration of the model and the applications it can support.