A Byzantine Fault Tolerant Protocol for Composite Web Services

This paper presents a Byzantine fault tolerant protocol for composite Web Services. We extend Castro and Liskov's well-known practical Byzantine fault tolerance method for the server client model and Tadashi Araragi's method for the agent system to a method for the composite Web Services. Different from other Byzantine tolerant methods for single web service, in composite Web Services we have to create replicas on both sides, while in the server-client model of Castro and Liskov's method, replicas are created only on the server side. We present a modular implementation, and experimental results demonstrate only a moderate overhead due to replication.