High Quality Content by WIKIPEDIA articles! Event stream processing, or ESP, is a set of technologies designed to assist the construction of event-driven information systems. ESP technologies include event visualization, event databases, event-driven middleware, and event processing languages, or complex event processing (CEP). In practice, the terms ESP and CEP are often used interchangeably, with CEP becoming a more fashionable term recently. ESP deals with the task of processing multiple streams of event data with the goal of identifying the meaningful events within those streams, employing techniques such as detection of complex patterns of many events, event correlation and abstraction, event hierarchies, and relationships between events such as causality, membership, and timing, and event-driven processes.