网格环境下的数据库访问和集成

为了集成网格环境中的数据库资源，促进网格应用支持现有数据库的访问，提出一种基于服务的数据库访问和集成系统(GridDBAdmin)。GridDBAdmin为用户提供了虚拟的全局逻辑数据库视图，支持用户使用现有的SQL语言同时访问多个数据库。系统由元数据服务和网格虚拟数据库服务构成。其中元数据服务负责发现含有用户所需数据的数据库，网格虚拟数据库服务提供全局逻辑视图，通过分布式查询机制将用户的SQL请求分解到具体的数据库中并进行结果合并。对基于Globus和OGSA-DAI工具包开发的原型系统进行了测试，得到了较好的结果。

Database Access and Integration on the Grid

To integrate existing database resources into the grid and encourage wider use of databases in a grid setting, a service-based database access and integration system, GridDBAdmin, is presented. GridDBAdmin provides a virtual global logical database view for the users and enables grid application to query existing multiple databases using SQL. The system is composed with MetaData Service(MDS) and Grid Virtual Database Service(GVDS). MDS searches the metadata catalog to find the physical databases that contain the required data. GVDS delegates global logical database and converts SQL query into search conditions to the physical databases, which uses a distributed query processing scheme to join multiple physical databases. Performance evaluation based on the response time shows the efficiency of the method. The system is fully implemented on the top of the Globus toolkit and OGSA-DAI.