A Fault-Tolerant Sequencer for Timed Asynchronous Systems

In this paper we present the specification of a sequencer service that allows independent processes to get a sequence number that can be used to label successive operations (e.g. to allow a set of independent and concurrent processes to get a total order on their operations). Moreover, we provide an implementation of the sequencer service in a specific partially synchronous distributed system, namely the timed asynchronous model. As an example, if a sequencer is used by a software replication scheme then we get the advantage to deploy server replicas across an asynchronous distributed system such as the Internet.