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分布事件通知服务的关键技术及其应用研究

Research on Key Technologies and Application of Distributed Event Notification Services

【作者】 汪洋

【导师】 王振宇;

【作者基本信息】 中国科学院研究生院(软件研究所) , 计算机软件与理论, 2004, 博士

【摘要】 Internet的广泛应用使得传统的基于请求/应答的点对点的同步通信不能满足大规模的动态分布式应用环境。基于事件通信的发布/订阅(Publish/Subscribe)模型是支持大规模分布式系统的有效通信方式。该模型支持发布者和订阅者在时间、空间和同步方面的非耦合以及多对多的通信模式,从而满足大规模分布事件通知服务的基本要求。 论文在分析和总结分布式事件系统的原理、应用和关键技术的基础上,对基于内容的事件过滤技术、复合事件检测技术和动态可重配的分布事件通知服务的体系结构等方面进行了重点研究。 首先,基于BDD(Binary Decision Diagram)模型,对基于内容的事件过滤方法进行了系统研究,利用BDD方法提出了一个事件过滤算法,对该算法进行了模拟试验,分析并比较了它与基于谓词索引、基于测试网络等方法在时间、空间和易维护性方面的优劣。 复合事件检测技术的运用使得基于事件通信机制的应用系统可以支持复合事件模式的表示,极大地扩展了系统的事件处理能力和灵活性。论文在大规模事件通知服务的通用框架基础上,分别从事件系统的事件模型、时间模型和观察模型探讨了复合事件的检测技术,在传统的有穷状态自动机基础上扩充了时间模型、参数化机制和并发模型,提出了一种基于自动机的有效复合事件检测方法,并将该方法与各种主流方法进行了对比分析。 基于以上核心技术的研究,论文中还研究了分布事件通知服务的体系结构,设计了一个动态可重配的分布事件通知服务。该体系结构允许增加事件处理功能,包括事件过滤和复合事件检测等,同时允许引入非功能方面的处理,包括安全控制交互和移动操作。 利用软件体系结构的思想,基于事件通知服务中间件和模型检查技术,对分布式控制系统进行了形式化分析与设计。设计了分布式控制系统体系结构的形式化描述语言ADL/Promela,并将ADL/Promela体系结构模型映射成模型检查工具SPIN可以分析的形式化模型,运用模型检查技术对分布式控制系统进行分析和检查,以提高分布式控制系统的设计与开发质量。 在理论和技术研究的基础上,论文以基于分布事件通知服务成功开发的智能化楼宇集成管理系统为例,展示了分布事件通知服务的应用价值。

【Abstract】 The wide application of Internet has changed the scales of distributed systems, which making the point-to-point and synchronous communication based on request/reply paradigm is not enough for the large-scale distributed application environment. The event-based middleware can be well used to build such large distributed systems. Publish/Subscribe scheme based on the event model (also called Event Notification scheme) supports many-to-many communication and provides the loose coupling of interaction in the aspects of time, space, and synchronization required in the large-scale distributed event services.Based on the brief analysis of the principles, applications and key technologies of distributed event notification services, this dissertation focuses study on the content-based event filtering, composite event detection, and configurable architecture of distributed event notification services.Firstly, the filtering mechanism of content-based Pub/Sub system is studied. An BDD based event filtering model is proposed in the dissertation. The BDD based approach is completely presented. Also "Predicate Indexing Based", "Testing Network Based", and other approaches are examined, and they are compared with the BDD based approach on the time, space and maintainability.Composite event detection (CED) extends the basic event-system and improves the flexibility by allowing application components to express their interest in complex composite patterns of basic events. This dissertation presents a model for composite event detection based on the framework for large-scale event notification services, discussing the CED based on the event model, time model and observation model, and then presents a CED model based on finite state automata extended with a time model, parameterization and concurrent model.Based on the above studies, a dynamically extensible and configurable architecture of distributed event notification service is designed, which is presented based on configuration management and meta-service mechanisms with the ability to customize and extend the subscription, event description, interaction protocol and configurationlanguages. The notification service allows dynamical extension and customization of the event notification service to satisfy not only functional requirements (such event filtering and CED), but also non-functional features (such as security control and mobility) from application domains.The analysis process for complex distributed control systems consists of proving or verifying that the designed system indeed meets certain specifications. However, both the design and the analysis may be formidable due to the complexity and magnitude of the system. From an analysis perspective, the complexity of a system can be reduced by imposing a hierarchical structure and abstraction on the architectural design. Currently, model checking has been demonstrated by more and more successes that it is an effective way to verify the construction of complex system satisfies to the requirements of reliability and correctness. An approach for formally analyzing distributed control systems at architectural level is illustrated by applying software architecture description and model checking techniques. Thus, a formal architecture description language, called ADL/Promela, which is used to express the architecture of distributed control system, is designed, and in order to analyze and check in formal way, the ADL/Promela is mapped into the formal model which can be analyzed and checked by SPIN.As an exemplification, an application system called Intelligent Building Management System (IBMS) based on the distributed event notification service has been designed and developed, and it is successfully used by several important projects.

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