Virtually-synchronous communication based on a weak failure suspector

Failure detectors (or, more accurately, failure suspectors, or FS) appear to be a fundamental service upon which to build fault-tolerant, distributed applications. It is shown that an FS with very weak semantics (i.e. that delivers failure and recovery information in no specific order) suffices to implement virtually synchronous communication (VSC) in an asynchronous system subject to process crash failures and network partitions. The VSC paradigm is particularly useful in asynchronous systems and greatly simplifies building fault-tolerant applications that mask failures by replicating processes. The authors suggest a three-component architecture to implement virtually synchronous communication: (1) at the lowest level, the FS component; on top of it, (2a) a component that defines new views, and (2b) a component that reliably multicasts messages within a view.