Quorum-based locking protocol for replicas in object-based systems

We discuss how to lock replicated objects by extending the quorum concept and perform methods on replicas in a nested invocation. Each method is issued to a quorum. If a pair of methods are compatible, their quorums may not intersect in our protocol even if one of the methods is an update type. If a method t is invoked on multiple replicas and each instance of t invokes another update method u, u is performed multiple times on replicas and then the replicas get inconsistent, i.e. redundant invocation. In addition, since each instance issues a request to its own quorum, more replicas are locked than the quorum number, i.e. quorum explosion. We discuss how to resolve the redundant invocations and quorum explosion