【作者】 王平；

【导师】 徐久强；

【作者基本信息】 东北大学 ， 计算机系统结构， 2011， 硕士

【摘要】 RFID应用系统中通常会采集到大量原始的RFID数据,如果将这些大量原始的RFID数据直接提交给业务系统处理,那么业务系统就会变得异常的复杂,不具有很好的扩展性和灵活性,不能适应不断变化的业务需求。RFID复合事件检测就是将大量原始的RFID数据按照一定的业务规则转换成具有一定业务逻辑意义的复合事件,以事件驱动的方式来驱动上层业务系统,使得业务系统从原始的RFID数据中解耦。本文深入研究了RFID复合事件的检测方法和模型。本文首先阐述了关于RFID复合事件检测的研究现状,对现阶段提出的一些检测方法和模型进行了深入地研究和分析,并指出了各自的优缺点。在此基础上,本文提出了基于规则引擎的RFID复合事件检测方法,并论证了其有效性和可行性。Rete算法是现阶段规则引擎中广泛使用的规则匹配算法,其数据结构被称为Rete规则网络。为了将Rete算法应用于RFID复合事件的规则匹配中,本文详细分析了RFID事件的特点以及Rete算法所存在的问题。针对RFID事件的特点,本文对Rete算法提出了两种改进机制。首先,我们提出了一种基于部分匹配过期的垃圾回收机制,通过该机制来删除Rete规则网络的缓存中大量过期的部分匹配结果,有效地减小了缓存的压力。其次,针对大规则数的Rete规则网络中出现节点缓存为空的现象,我们提出了一种基于β缓存状态索引的无效连接测试过滤机制,对由于节点缓存为空而导致的Rete规则网络中连接测试节点测试无效的情况进行提前过滤,有效地提高了规则匹配性能。本文最后详细介绍了在开源的规则系统Drools中对这两种机制的实验测试情况,实验结果表明,使用本文提出的改进Rete算法作为规则引擎的规则匹配算法能够有效地适用于RFID复合事件的检测。更多还原

【Abstract】 Much raw data often collected in the RFID application systems, will make the business systems become abnormally complex, without good expansibility and flexibility, and can’t adapt to changing needs of the business, which directly deals with the massive primitive RFID data. RFID composite events detection is to convert a large number of original RFID data according to certain business rules to composite events with certain significance of business logic to drive the upper business system in event-driven way, which makes the business system decoupling from the original RFID data. This essay deeply studied the methods and models for detecting RFID composite events.This essay first expounded the present research development on RFID composite events detection, thoroughly studied some test methods and models, and pointed out the advantages and disadvantages of each. On this basis, this paper proposed the detection method of RFID composite events based on rules engine, and demonstrated its effectiveness and feasibility. Rete algorithm is now widely used in rules engine as a kind of rules matching algorithm, and its data structure is called Rete rules net. In order to make Rete algorithm apply to RFID composite events detection, the essay analyzed the characteristics of RFID events and the existing problems on Rete algorithm. According to the characteristics of RFID events, this essay proposed two improved mechanisms for Rete algorithm. First, we proposed a Rete garbage collection mechanism based on the life cycle of the partial matching, through which to delete expired partial matching results in the cache of Rete rules net, effectively reduced the pressure of cache. Second, considering the phenomenon that the caches of nodes in Rete rules net with a large number of rules are empty, we proposed a filtering mechanism based on the index of the cache state. By filtering the invalid connection test for the nodes whose caches are empty in advance, it effectively improved the match performance in Rete rule net.Finally, this essay introduced in detail the development of the two improved mechanisms in the rules system Drools, and the experiment results showed that the proposed improved Rete algorithm as the rules matching algorithm of rules engine can be effectively used in the detection of RFID composite events.更多还原