Timing Failure Detection and Real-Time Group Communication in Quasi-Synchronous Systems

Carlos Almeida and Paulo VerĂ­ssimo

Selected sections of this report will appear in the Proceedings of the 8th Euromicro Workshop on Real-Time Systems, L'Aquila, Italy, June 1996.


This paper addresses the problem of having real-time group communication in systems that are not completely synchronous (quasi-synchronous). This situation can happen when load is not completely controlled thus not ruling out overload scenarios. This is usually related to dynamic characteristics of the application and/or environment. Usually, in such systems, temporal guarantees can only be made to the highest priority messages.

In such scenario we propose to use the highest priority messages (or a dedicated synchronous channel if available) to implement a timing failure detection service. By using this service together with the communication protocols, we are able to provide safety in a timely fashion, which is of utmost importance for distributed fault-tolerant real-time applications.

Also available extended report (gzip postscript).