Guaranteeing Idempotence for Tightly-Coupled, Fault-Tolerant Networks

This paper presents techniques for guaranteeing idempotent semantics for classes of network operations in fault-tolerant networks. This is accomplished through operation transformation and message filtering. The conventional response to a failed or corrupted message transmission is to retransmit the failed message. This retry mechanism can lead to duplicate message delivery. If duplicated messages are non-idempotent, duplicate message delivery places the system into an inconsistent state. We explore methods of guaranteeing message idempotence at both the application and network protocol levels.