一种基于XML的复合事件模型及其订阅语言

A XML-Based Composite Event Model and Its Subscription Language

基于内容的Pub/Sub系统能够为大范围软件集成提供松耦合的、可扩展的集成能力,越来越引起人们的重视.现存的方法主要集中在对单一事件的匹配,缺乏对复合事件模型及其订阅语言的研究.针对此问题,文章给出一种基于XML事件的复合事件模型及其订阅语言,该模型包括事件时序逻辑模型和事件复合模式,并扩展了XML-QL语言得到复合事件订阅语言EXML-QL支持事件复合模型和模式;最后,依据该订阅语言的特点构造复合事件匹配算法,给出该算法的分析和验证.

Content-based Pub/Sub system is gaining increasing popularity due to its loose coupling and scalable integration capability in the aspects of building large-scale software integrations. Unlike in the traditional address-based unicast or multicast, its core problem is how to match events by predicates on the contents of events. Currently, mostly existing approaches mainly limit at the ＂one-to-one＂ event matching and its matching predicates are composed of the conjunction and disjunction of non-semantic constraints. In fact, the composite event matching is required in many scenarios, typically including ＂one-to-many＂ or ＂many-to-one＂ matching. This kind of event matching enables application components to express more interest about the occurrence of complex patterns of events. A XML-based composite event model that consists of the temporal logical model and the event composite pattern is presented in the paper. The temporal logical model describes the temporal relations of events in distributed environments; the event composite pattern describes the different triggering and transferring patterns appearing the different application scenarios. Based on the composite event model, a subscription language called EXML-QL is introduced by adding the block-variables and the temporal logical operators in XML-QL language to support XML-based composite event patterns. Finally, according to the peculiarities of the subscription language, a composite event matching algorithm is presented and analyzed.