Compound event expressions allow you to combine primitive events to form event scenarios. Event expressions provide a robust, precise notation for expressing complex patterns on event streams. Complex event expressions are not new; they have been the subject of research in database trigger languages since the 1990s and have been used since then in event engines in a variety of disciplines. See our Event Processing Resources page for more details. What What is new is their application to real-time data streams on the Web.
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