Patent US 4,376,982

A communication system includes a plurality of requestors and a plurality of responders representing resources. A protocol exercised by all elements provides accurate and consistent interconnection of all elements in a system where messages may be delayed or lost. Requestors are provided with means to transmit a request for use of a plurality of resources, respond to acceptances from one or more responders and create a cooperative relationship by transmitting a confirmation to one responder and cancellation of the request to all other responders. Responders become committed to a requestor by signalling an acceptance to a request if a previous acceptance has not been transmitted, or if the resource is not already committed to another requestor, and a subsequent confirmation signal is received. The responder does not become committed after transmitting an acceptance if the next signal directed to it from the requestor is a request cancellation. Request signals and cancellation signals by a requestor can either be broadcast simultaneously to all responders of a class or transmitted to particular, designated responders, one at a time.