Unified Semantics for Event Correlation over Time and Space in Hybrid Network Environments

The recent evolution of ubiquitous computing has brought with it a dramatic increase of event monitoring capabilities by wireless devices and sensors. Such systems require new, more sophisticated, event correlation over time and space. This new paradigm implies composition of events in heterogeneous network environments, where network and resource conditions vary. Event Correlation will be a multi-step operation from event sources to final subscribers, combining information collected by wireless devices into higher level information or knowledge. Most extant approaches to define event correlation lack a formal mechanism for establishing complex temporal and spatial relationships among correlated events. Here, we will focus on two subjects. First, we define generic composite event semantics, which extend traditional event composition with data aggregation in wireless sensor networks (WSNs). This work bridges data aggregation in WSNs with event correlation services over distributed systems. Secondly, we introduce interval-based semantics for event detection, defining precisely complex timing constraints among correlated event instances.