Active Database Execution Model
The execution model of an active database describes how a set of ECA rules behave at run time.
The execution model describes how a set of ECA rules (i.e., active database rule base) behave at run time [2, 4]. Any execution model of an active database must have support for (i) detecting event occurrences, (ii) evaluating conditions, and (iii) executing actions.
If an active database supports composite event detection, it needs a policy that describes how a composite event is computed. A typical approach is to use the event consumption modes as described in Snoop : recent, chronicle, continuous, and cumulative. In the recent event context, only the most recent constituent events will be used to form composite events. In the chronicle event context, events are consumed in chronicle order. The earliest unused initiator/terminator pair are used to form the composite event. In the continuous event context, each initiator starts the detection of a new composite...
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