Abstract
Abstract. 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.
Highlights
Metadata service is an important part of building geographic information data sharing service system[2], and a specific one pattern of geographic information network distribution service[5]
National metadata service system of surveying and mapping results is based on OGC CSW 2.0.2 standard
The portal showcases all the metadata in central node harvested from network nodes, provides web interface and a variety of ways to query, it provides management interfaces for central node and network nodes interconnection
Summary
Metadata service is an important part of building geographic information data sharing service system[2], and a specific one pattern of geographic information network distribution service[5]. It is an OSGeo incubation project, supportting OGC CSW 2.0.2 It is a standard based and decentralized spatial information management system, designed to enable access to geo-referenced databases and cartographic products from a variety of data providers through metadata query and access, enhancing the spatial information exchange and sharing between organisations and their audience. It can provide access service for customers with a convenient and variety of source spatial data and thematic maps. At present central node manages more than 1.1 million metadata which harvested from more than 30 network nodes
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