A scheme for reliable real-time messaging with bounded delays

摘要

Network-based real-time computing applications that require tightly bounded end-to-end delays have been increasing at a steady rate in recent years. A messaging layer that yields tight bounds on the latencies in detecting message losses and enables the application layer to initiate a timely recovery action has thus become highly desirable. In this paper, we present a new reliable real-time messaging scheme called the Delay-Bounded Reliable Messaging Scheme (DB-RMS) that is aimed at meeting such requirements. It is built on top of the User Datagram Protocol sub-layer. DB-RMS provides multiple service options, each with different fault detection/recovery capabilities and different costs in terms of the execution overhead. This feature makes DB-RMS suitable for a variety of applications. In this paper, the DB-RMS service options and the corresponding support protocols are presented first followed by a formal analysis on the detection and reaction latency bounds under various service options. A messaging layer prototype using DB-RMS has been implemented. To demonstrate the practice of the DB-RMS, we implemented a clock synchronization algorithm for 802.11 wireless local area networks on top of the DB-RMS messaging layer. Performance measurements of the prototype implementation have been taken, and the positive results obtained are also presented.