基于事件的发布-订阅系统模型

Internet的广泛应用已经改变了分布式系统的规模，使得传统的基于请求/应答的点对．点的同步通信已不能很好地满足大规模的动态分布式应用环境。为了加强大规模的分布式环境中实体之间的通信协作，系统要求更加灵活的通信模型，以反映应用的动态和非耦合特性。基于事件通信的中间件是建立大规模分布式系统的有效方式，发布者/订阅者（Publisher/subscriber）是目前广泛使用的基于事件的通信模型，支持发布者和订阅者之间在时间、空间和同步方面的非耦合以及多对多的通信模式，提供大规模系统所要求的交互间的松散耦合。本文详细阐述了事件系统的组成以及基于事件系统的PUB／SUB模型，提出了基于PUB／SUB的事件系统中间件的核心及实现的关键，这些中间件为大规模的分布式应用提供更多和更有力的保障。

Effects of Decomposed Products of Grass Charcoal on the Adsorption of Cu and Zn

The Internet application 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-scales dynamically distributed application environment. In order to communicate and cooperate efficiently among the entities in a large-scale distributed system, it needs more flexible communication models to reflect the dynamic and decoupled nature of the applica tions. The evenvbased middleware can be well used to build such large systems. Publisher/Subscriber scheme based on the event model supports many-to-many communication and time, space, and synchronization decoupling of subscribers and publishers and provids the loose coupled form of interaction required in the large-scale system. The paper specifies the event model and the publisher/subscriber model, and presents the key factors of event-based middleware architecture.