A Middleware for Exactly-Once Semantics in Request-Response Interactions

Although the need for the exactly-once request-response interaction pattern is ubiquitous in distributed systems, making it work in practice is anything but simple. Ensuring the at-most-once part of the invocation is relatively easy. Unfortunately, the same is not true for the at-least-once guarantee, which depends on the recovery from crashes of the client, the server and the network. This is what makes the exactly-once interaction so difficult in practice: client and server must log their actions into stable storage, and they must be able to restart the network connections. In this paper, we present a middleware that implements the exactly-once request-response pattern, in presence of network and endpoints crashes. The main contribution of our work is to release the programmer from the complex tasks of recovering from message losses and network crashes.