How are HCEP and Complex Event Processing (CEP) related?

CEP has been around since the 1990s, both conceptually and technologically. In recent years, it has become increasingly synonymous with "stream processing." While both terms are often used interchangeably, some distinctions can be made. CEP typically focuses on identifying complex patterns and dependencies within event streams, such as recognizing a specific event based on a combination of simpler events. In contrast, stream processing often involves simpler tasks like aggregation, filtering, and transformation of individual events.

For example, a CEP application might identify a specific event, like a marching band performance, by recognizing a combination of simpler events, such as drumbeats, crowd cheers, and changes in instrument frequency. A stream processing application can process individual website clicks or transactions, analyzing and responding to each event independently.

In practical terms, "complex event processing" and "stream processing" are often used interchangeably. Many modern technologies, such as Apache Kafka and its ecosystem of stream processing engines, support both complex pattern detection and simpler event processing tasks.