An analysis of fault detection latency bounds of the SNS scheme incorporated into an Ethernet based middleware system

The supervisor-based network surveillance (SNS) scheme is a semi-centralized network surveillance scheme for detecting the health status of computing components in a distributed real-time (RT) system. An implementation of the SNS scheme in a middleware architecture, named ROAFTS (real-time object-oriented adaptive fault-tolerance support), has been underway in the authors´ lab. ROAFTS is a middleware subsystem which is layered above a COTS (commercial-off-the-shelf) operating system (OS), such as Windows XP or UNIX, and functions as the core of a reliable RT execution engine for fault-tolerant (FT) distributed RT applications. The applications supported by ROAFTS are structured as a network of RT objects, named time-triggered message-triggered objects (TMOs). The structure of the prototype implementation of the SNS scheme is discussed first, then a rigorous analysis of the time bounds for fault detection and recovery is provided.