【作者】 梁宝兰；

【导师】 曾一；

【作者基本信息】 重庆大学 ， 计算机软件与理论， 2006， 硕士

【摘要】 目前,随着计算机技术以及网络技术的迅速发展,信息系统也正朝着分布式与信息资源共享两个方面发展,所以如何有效地解决分布式信息系统下的信息资源共享问题,已经成为信息系统发展的一个主要研究方向。利用面向对象方法开发的分布信息系统的信息资源的表现形式为对象状态信息,所以要实现信息资源的共享就必须实现对象的持久。要有效地从分布式信息系统上获得共享信息资源,就要提高系统访问共享持久对象的效率,同时也要平衡系统的负载,也就是持久对象是可迁移的。对于一些特殊的分布式信息系统,例如拍卖系统、预订系统、交通信息系统等,其客户都需要监视它感兴趣信息的实时变化情况。本文研究了分布式信息系统资源共享发展的现状,然后比较研究了DCOM、J2EE以及CORBA等三种流行的分布式对象技术,并详细介绍了CORBA技术,其次还比较研究了对象持久化的解决方法,分析了它们的优缺点。本文以有效的解决分布式信息系统的信息资源共享为目的,提出了基于消息中间件的持久对象扩展模型。该模型在原持久状态服务的基础上,增加了缓存管理来提高客户对共享持久对象的访问速度,并通过消息中间件实现持久对象的共享与迁移,利用对象序列化技术把持久对象序列化为XML文件,实现持久对象的网络传输。本文还以该扩展模型为基础,以分布式拍卖系统为背景完成了验证性的实现,该实现利用IDL描述了系统的分布式对象接口,利用PSDL描述了系统的持久对象,并制定了利用消息中间件发布/订阅消息的格式与协议。本文还实现了Java对象与XML之间的无缝转换,实现了持久对象的传输与迁移,为解决异质数据库之间的数据交换提供了一种途径。最后对本文所做的工作做了总结,并对将来在该研究方向提出了一些展望。更多还原

【Abstract】 Nowadays,as the rapid development of computer technology and network technology, information system is becoming distributed and sharable. Therefore, how to efficiently share information in distributed environment has become one of most important research issues in information system research.The information resource is represented by object states in distributed information system which is developed with object oriented development method. So, to share information resource, the object must be persistent. In order to get the sharing information resource, it must raise the efficiency of accessing persistent objects and balance the system load, in other words, the persistent objects must be able to be migrated. In some special distributed information system, such as auction systems, reservation systems, traffic information systems and so on, their clients perhaps want to monitor the information of interest.This paper researches the present status of resource sharing in distributed information system, and researches three popular distribute object technique, DCOM, J2EE and CORBA, and introduce CORBA in detail. Then it studies the solutions of object persistence, and analyzed their advantage and disadvantage. Aiming at effective share of information resource in distributed information system, it presents an extended model of persistent state service based on message oriented middleware. On the based of original persistent state service, this extended model adds cache management to let client access the persistent objects more rapidly. It uses message oriented middleware to share and migrate persistent objects. Persistent objects are serialized with XML files, which can be transmits in network. This paper used this extend model to implement a distributed auction system,which uses IDL to describe the distributed object interfaces, and uses PSDL to describe the persistent objects. The message format and the publishing and subscribing protocol in message oriented middleware are defined in this paper. In the distributed auction system, it also implements the seamless conversion between Java objects and XML files, so persistent objects can be transferred and migrated freely, and it provides efficient approach to exchange data between heterogeneous database for various software. Finally, it summarized the whole study更多还原