A locking mechanism for a data resource is disclosed, which can operate across LANs and a WAN. The technique temporarily imposes an extended lock on the requested data resource. While the extended lock is in force, all lock and unlock requests issued by the same client for the resource are managed exclusively by the local server. Once the last lock has been released, or after a timeout interval, the extended lock is canceled. Traffic across the WAN is reduced to a minimum of one round trip.