Replica Management in Object-based Systems

In object-based systems, objects are encapsulations of data and procedures named methods and methods are invoked in a nested manner. We discuss how to lock replicated objects by using the quorum-based scheme. If a pair of methods op1 and op2 are compatible, each method is surely performed on some replica, but both of them may not be performed on a same replica. Compatible methods are exchanged between the replicas if both the methods are not performed on any of the replicas in our protocol. If a method op1 is invoked on multiple replicas and each instance of the method op1 invokes a method op2, op2 is performed multiple times on an object, i.e. redundant invocation. In addition, since each instance of op1 issues a request op2 to its quorum, more number of the replicas are locked than the quorum number of op1. This is quorum explosion. We discuss how to resolve these redundant invocations and quorum explosion.