DESIGN AND PRACTICE ON METADATA SERVICE SYSTEM OF SURVEYING AND MAPPING RESULTS BASED ON GEONETWORK

摘要

Based on the analysis and research on the current geographic information sharing and metadata service, we design, develop and deploy a distributed metadata service system based on GeoNetwork covering more than 30 nodes in provincial units of China.. By identifying the advantages of GeoNetwork, we design a distributed metadata service system of national surveying and mapping results. It consists of 31 network nodes, a central node and a portal. Network nodes are the direct system metadata source, and are distributed arround the country. Each network node maintains a metadata service system, responsible for metadata uploading and management. The central node harvests metadata from network nodes using OGC CSW 2.0.2 standard interface. The portal shows all metadata in the central node, provides users with a variety of methods and interface for metadata search or querying. It also provides management capabilities on connecting the central node and the network nodes together. There are defects with GeoNetwork too. Accordingly, we made improvement and optimization on big-amount metadata uploading, synchronization and concurrent access. For metadata uploading and synchronization, by carefully analysis the database and index operation logs, we successfully avoid the performance bottlenecks. And with a batch operation and dynamic memory management solution, data throughput and system performance are significantly improved; For concurrent access,, through a request coding and results cache solution, query performance is greatly improved. To smoothly respond to huge concurrent requests, a web cluster solution is deployed. This paper also gives an experiment analysis and compares the system performance before and after improvement and optimization. Design and practical results have been applied in national metadata service system of surveying and mapping results. It proved that the improved GeoNetwork service architecture can effectively adaptive for distributed deployment requirements, performance improvement and optimization of the system guarantee its continuous and stable running on the internet.