Study On Sharing Persistent Objects In Distributed Information System

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...