FRAME: Fault Tolerant and Real-Time Messaging for Edge Computing

Edge computing systems for Industrial Internet of Things (IIoT) applications require reliable and timely message delivery. Both latency discrepancies within edge clouds, and heterogeneous loss-tolerance and latency requirements pose new challenges for proper quality of service differentiation. Efficient differentiated edge computing architectures are also needed, especially when common fault-tolerant mechanisms tend to introduce additional latency, and when cloud traffic may impede local, time-sensitive message delivery. In this paper, we introduce FRAME, a fault-tolerant real-time messaging architecture. We first develop timing bounds that capture the relation between traffic/service parameters and loss-tolerance/latency requirements, and then illustrate how such bounds can support proper differentiation in a representative IIoT scenario. Specifically, FRAME leverages those timing bounds to schedule message delivery and replication actions to meet needed levels of assurance. FRAME is implemented on top of the TAO real-time event service, and we present empirical evaluations in a local edge computing test-bed and an Amazon Virtual Private Cloud. The results of those evaluations show that FRAME can efficiently meet different levels of message loss-tolerance requirements, mitigate latency penalties caused by fault recovery, and meet end-to-end soft deadlines during normal, fault-free operation.