MANAGEMENT OF SHARED DATA IN FEDERATED COOPERATIVE PEER ENVIRONMENT

Abstract

In a network of autonomous cooperating agents, complex distributed objects can be shared and exchanged. The novel feature presented in this paper is handling complex distributed objects, that we claim to be essential for cooperating teams of engineers e.g. in CIM, and in an environment that supports the integration of a group of expert systems. A model is presented here for the creation, retrieval, and modification of complex objects that are distributed in a federation of cooperating agents. The information that agents are willing to share with others in the federation is uniformly represented as inter-related objects. This defines a distributed object graph that spans over the entire federation of agents. Complex objects form a connected subgraph of this distributed object graph. To support safe cooperation and sharing of complex objects, while preserving agents’ autonomy, agents can bilaterally negotiate the access rights and deletion policies on distributed complex objects and when necessary these rights are propagated. Since the access rights are negotiated among agents, and not imposed by a central authority, the autonomy of each agent is fully maintained. To enable application programs to define and retrieve a complex object as a single entity, a linearization mechanism is introduced in the paper. The model described here has been developed as a part of the PEER system. PEER is a federated objectbase, designed and implemented as part of the Archon abstract machine, which provides an environment for the integration of heterogeneous cooperating expert systems.