Distributed schema management in a cooperation network of autonomous agents

Abstract

For data-intensive, computation-intensive, collaborative engineering application environments such as computer-integrated manufacturing, a natural architecture is a network of loosely-coupled, autonomous, and heterogeneous agents, where each agent runs on a single workstation. Each agent is autonomous in its decision to keep apart of its information private and to share another part of its information with some other agents. Loose and tight interdependencies among agents' information can be denned through the integration and interrelation of agents' schemas. Complex derivation/integration of agents' schemas and their referential integrities can be supported by a schema management mechanism. This facility, that we claim to be essential for cooperating teams in industrial automation applications, is the novel feature presented in this paper. The integrated schema created locally at each agent is a coherent view on the local and the global information accessible by this agent. Hence, the physical and logical distribution of information through the network is entirely hidden from the end user of the network and absent from their queries. The schema management mechanism supports the definition of complex derived types and derived mappings, remote referencing among information stored in various agents, and their referential integrities. The schema management mechanism described here is developed as a part of Peer. Peer is designed and prototypically implemented as part of the Archon abstract machine, which provides an environment for the integration of heterogeneous cooperating expert systems.

On leave from California State University.