Guarantees for decentralized event correlation

Many distributed applications rely on forms of event correlation, which result in atomic delivery of multiple events aggregated by following process-specific criteria. Generally, more than one process is aggregating events, implying that events are multicast. While delivery guarantees for multicast scenarios with single event/message delivery are well understood, existing systems and models for aggregated deliveries either consider only unicast, centralized setups, or focus on efficiency thus providing only best-effort guarantees. This paper first reviews properties and grammar previously proposed for decentralized event correlation. While these properties compose an essential set for fair correlation of events in a decentralized setting, there are further properties that may be explored. This paper will also discuss these additional properties and describe the challenges and open questions they present.