The Research And Implementation On Access Broker In Distributed Virtual Environment

With the development of Distributed Virtual Environment (DVE), data in DVE become more massive and more complicated. So it is urgent to propose a new kind of effective method to manage those data in DVE, according to the characteristic of those data.To make full use of the data resource, a hierarchy architecture of massive data management system based on Grid is proposed, which consists of Metadata Catalog and Access Broker. In this thesis, the technology about Access broker is studied and the Weapon Information Storage System is designed and implemented. The primary contributions of this thesis include the following three parts:Firstly, the architecture of the Access Broker middleware is proposed and the framework of it is completed. The Access Broker middleware consists of one or more Access Brokers, which are distributed in DVE. Every Access Broker manages the data resource in some region. All of them collaborate with each other to offer the flexible, effective, transparent, uniform data access service to the users.Secondly, the characteristic of the data transfer in DVE is analyzed, and a new transfer protocol named DveFTP is brought forward, which is on the basis of FTP, and is fit for DVE. In DveFTP, several kinds of techniques are adopted to improve the transfer efficiency, such as Multi-site Parallel Transfer algorithm and Fast Parallel File Replication algorithm. When data type and user requirement is different, DveFTP can choose corresponding transfer policy. DveFTP can improve the initialization, replicating and realtime transfer in the process of simulation.Lastly, to satisfy the requirement of distributed virtual naval war, a Weapon Information Storage System is developed with oracle and ASP. The Weapon Information Storage System and other storage system provide data storage service through Access Broker middleware. Administrators or users can access the weapon information by client program of storage system itself. It is a complete, employ conveniently, fault tolerant system and has been submitted to users successfully.