AVCast : New Approaches For Implementing Availability-Dependent Reliability for Multicast Receivers

Today's large-scale distributed systems consist of collections of nodes that have highly variable availability - a phenomenon sometimes called churn. This availability variation is often a hindrance to achieving reliability and performance for distributed applications such as multicast. This paper looks into utilizing and leveraging availability information in order to provide availability-dependent message reliability for multicast receivers. An application (e.g., a publish-sub scribe system) may want to scale the multicast message reliability at each receiver according to that receiver's availability (in terms of the fraction of time that receiver is online) ifferent options are that the reliability is independent of the availability, or proportional to it. We propose several gossip-based algorithms to support several such predicates. These techniques rely on each node's availability being monitored in a distributed manner by a small group of other nodes in such a way that the monitoring load is evenly distributed in the system. Our techniques are light-weight, scalable, and are space- and time-efficient. We analyze our algorithms and evaluate them experimentally by injecting availability traces collected from real peer-to-peer systems