Distributed service request bus using tokens to resolve collisions

摘要

A transfer request bus (25) is described which is suitable for use in a data transfer controller processing multiple concurrent transfer requests despite the attendant collisions which result when conflicting transfer requests occur. Transfer requests are passed from an upstream transfer request node (318) to downstream transfer request node (300) and thence to a transfer request controller with queue (320). At each node a local transfer request can also be inserted to be passed on to the transfer controller queue. Collisions at each transfer request node are resolved using a token passing scheme wherein a transfer request node possessing the token allows a local request to be inserted in preference to the upstream request. <IMAGE>