Efficient Method for Processing Consecutive Events over Streams with a Negation Link.

Recently developed query processors for complex events filter data streams to match specific patterns and transform streaming data into meaningful information. To specify the patterns to be matched, complex event processing languages adopt a negation to present an event that should not appear at a specific position. A negation engenders more expressive query forms; however, the indexes must be looked up for each result sequence. In this paper, we review an efficient processing technique for a negation and propose the consecutive event processing in negations (CEPIN) for processing consecutive events in a query with negations. The key component of this proposal is the investigation as to whether the present event type is identical to a previous event type. If it is identical, a calculation to determine the resulting sequence range is not necessary; moreover, the time required for the processing of a negation and the reverse order of a link can be saved. Our experiment shows a reduction in the number of processes and calculations required per event.