A distributed implementation of sequential consistency with multi-object operations

Sequential consistency is a consistency criterion for concurrent objects stating that the execution of a multiprocess program is correct if it could have been produced by executing the program on a mono-processor system, preserving the order of the operations of each individual process. Several protocols implementing sequential consistency on top of asynchronous distributed systems have been proposed. They assume that the processes access the shared objects through basic read and write operations. This paper considers the case where the processes can invoke multi-object operations which can read or write several objects in a single operation atomically. It proposes a particularly simple protocol that guarantees sequentially consistent executions in such a context. The previous sequential consistency protocols, in addition to considering only unary operations, assume either full replication or a central manager storing copies of all the objects. In contrast, the proposed protocol has the noteworthy feature that each object has a separate manager Interestingly, this provides the protocol with a versatility dimension that allows deriving simple protocols providing sequential consistency or atomic consistency when each operation is on a single object.