Research On Complex Event Detection Technology Over Event Stream

Event stream management has become a very popular research issue in database field and gained wide attention in recent years. Actually, lots of applications are event-driven. For example, the metadata collected by RFID equipments are simple events. The transaction and business data changes also can be considered as events in businiess process management. In these application areas, these continuous arrival events constitute event streams without bound.Modern business processes produce massive and different types of events. Therefor, it’s very difficult to find the valuable event from these events. To help enterprises find interesting or significant events, we need a new software model to handle a large number of different events. The rising event detection technology undoubtedly plays an important role.In order to detect the complex event from huge volume of event streams effectively, we often need to consider updating and deleting of event stream, processing over out of order event stream, negation event processing and optimization of query results.Based on the above-mentioned problems in event detection, the contributions of the thesis are as follows:(1) An RFID event flow scenarios is described first and the hash list complex event detection algorithm is presented based on it. Intermediate results are stored in the special structure of the hash list, and design an effective hash map in order to speed up the matching process.(2) For out of order events, this paper deals well with them by using the special structure of the hash list.(3) Due to event stream has characteristics of real-time and infiniteness. cleaning up the outdated intermediate results in memory timely is required. Here, this paper proposes an effective event stream updating and deleting mechanism based on sliding window constraints.(4) Event detection is often for the purpose of event prediction effectively. In order to avoid duplicate predictions, this paper presents the definition of the minimal occurrence according to the requirement of query results and searchs the minimal occurrence efficiently using rule tree.According to the theoretical analysis and experimental evaluations, this paper can show that the complex event detection method of event stream has great efficiency and feasibility.