Adaptive and Dependable Group Communication
Raimundo José de Araújo, Macêdo · 2008
Group Communication is a powerful abstraction that is being widely used to manage consistency problems in a variety of distributed system models, ranging from synchronous, to time-free asynchronous model. Though similar in principles, distinct implementation mechanisms have been employed in the design of group communication for distinct system models. However, the hybrid nature of many modern (real-time) distributed systems, with dynamic and varied QoS guarantees, has put forward the need for integrated models. Furthermore, adaptation with degraded service is a common requirement in such scenarios. This paper tackles this new challenge by introducing a generic group communication mechanism called the Timed Causal Blocks. Because of its integrated feature, the Timed Causal Blocks mechanism is capable of handling group communication for both synchronous and asynchronous distributed systems, dynamically adapting to the available QoS. For example, it can dynamically switch to the asynchronous version when the run-time system can no longer guarantee a timely operation. Formal properties of the integrated model and related mechanisms, with proof sketches are presented.