Research On Key Technologies And Application Of Distributed Event Notification Services

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.