Durative Events in Active Databases

Active databases are DBMS which are able to detect certain events in the environment and trigger actions in consequence. Event detection has been subject of much research, and a number of different event specification languages is extant. However, this is far from being a trivial or accomplished task. Most of these languages handle just instantaneous events, but it has been noticed that a number of situations arise where it would be interesting or even necessary to handle durative events. We elaborate on a given specification language which combines instantaneous and durative events, revealing some issues which must be taken into account when the semantics of event composition is defined.