Invocation Protocol on Object Replicas

Objects are replicated in order to increase reliability and availability of an object-based system. Each method t is invoked on a subset of the replicas which is named quorum of t. Suppose each instance of t on the replicas invokes another method u on an object y. Since each instance of the method t invokes the method u, the method u is performed multiple times on the object of y. Here, the object y gets inconsistent This is redundant invocation. In addition, if each instance of the method t issues a request u to its quorum, more number of the replicas are manipulated than the quorum number of the method u. This is quorum expansion. We discuss a protocol to invoke methods on replicas in a nested manner where the redundant invocation and quorum expansion are resolved. We evaluate the protocol on how many replicas are manipulated and requests are issued.