| Active database, compared with traditional database has monitoring and alarmingfunctions, can take the initiative to deal with unusual circumstances, selects appropriateinterventions, and also has the ability of automatic recovery. One of the keys to achieveactive mechanism of an active database is through the detection and handling of eventsto stimulate database management system to monitor the state of the database system.Reference net, a senior network system of Petri net, is able to perform simultaneousmonitoring of events, Reference net modeling can accurately express the semantics ofactive database rule sets. Therefore, a method for reference net composite eventsmonitoring is used here to make the active database system better meet the needs ofpractical application.This paper explains the theory of active database, proposes a composite eventsdetection algorithm for active database based on reference net, constructs a referencenet layer model to the whole rule set; with the S-A rules model, the definition of theform of events is extended, the definition of active rules in the form of events,conditions match is reduced, the ability of semantic description of the events isenhanced. This paper gives a detailed analysis of the termination issue of the activerules, and then presents a relatively effective solution to this problem. The use ofreference net enables the system to monitor simultaneously on different types of events,allows the system do composite event monitoring in line with application requirementsunder the constrained environment. Finally, the event model of tactical plan recognitionis proposed, the application of monitoring active database composite events based onreference net is to achieve actively monitoring tactical plan of the military scene whichhas been set artificially, incidence matrix is used here to analyze the terminationproblem on tactical plan, these demonstrate the feasibility of the proposed planrecognition method. |
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