Research And Application On Metadata Service For Distributed Simulation Resources In Grid

Many kinds of resources in large and distributed environment related to computing environment are required by distributed simulation, access and management of these resources is a complex task, which can be accomplished by combining it with the techniques of Grid. Grid is an emerging technology based on the Internet. It makes the high-speed Internet, high-performance computers, large databases, sensors and other valuable equipments be integrated. So that, the resources distributed in different geographic locations make up a virtual unprecedented powerful information system. At last the Grid realizes comprehensive share of computing resources, data resources, communication resources, expert resources and so on.In this paper, we study on MDS (Metadata Service) , which is one of the critical issues in the research of the database access and integration on the Grid. Metadata is the description of the capabilities of a database service and the accessed data information, which is other Grid services and applications relied on to integrate the database services. It is the key for transparent distribution, storage and management of the database resources. On the research of MDS, we advance a Hierarchical distributed MDS (HdMDS). HdMDS utilizes the layered distribution structure, and provides both the metadata management and database service discovery. Metadata management includes registry, access and manage the metadata. And it implements the mapping of the logical metadata to the physical metadata. So the system can access to the database resources on the Grid transparently. The service log is adopted to improve the searching performance of the available database services, which drastically enhances the hit rate of the service discovery.Based on the MDS advanced above, we advance a grid query system (GQS). And the Grid middleware is used to integrate the distributed databases in this system. The system realizes the HdMDS and the GDQS (Grid Distributed Query Service) functional modules defined by user own. Under the limited experimental environment, we implement to query the distributed databases .The system provides support for the further research on access and management of simulation resources in Grid .