随着商业和科学研究领域中数据密集型应用越来越广泛,提供透明地访问分布式的、异构的数据源将成为这种应用的关键。提出一种基于网格数据仲裁服务(Grid Data Mediation Service,GDMS)的数据集成系统,它能够把网格中的分布式的、异构的...随着商业和科学研究领域中数据密集型应用越来越广泛,提供透明地访问分布式的、异构的数据源将成为这种应用的关键。提出一种基于网格数据仲裁服务(Grid Data Mediation Service,GDMS)的数据集成系统,它能够把网格中的分布式的、异构的数据源表示成一个逻辑上虚拟的数据源,并设计出了一种灵活的映射模式来描述构建虚拟数据源的过程。展开更多
The volume of publically available geospatial data on the web is rapidly increasing due to advances in server-based technologies and the ease at which data can now be created.However,challenges remain with connecting ...The volume of publically available geospatial data on the web is rapidly increasing due to advances in server-based technologies and the ease at which data can now be created.However,challenges remain with connecting individuals searching for geospatial data with servers and websites where such data exist.The objective of this paper is to present a publically available Geospatial Search Engine(GSE)that utilizes a web crawler built on top of the Google search engine in order to search the web for geospatial data.The crawler seeding mechanism combines search terms entered by users with predefined keywords that identify geospatial data services.A procedure runs daily to update map server layers and metadata,and to eliminate servers that go offline.The GSE supports Web Map Services,ArcGIS services,and websites that have geospatial data for download.We applied the GSE to search for all available geospatial services under these formats and provide search results including the spatial distribution of all obtained services.While enhancements to our GSE and to web crawler technology in general lie ahead,our work represents an important step toward realizing the potential of a publically accessible tool for discovering the global availability of geospatial data.展开更多
文摘随着商业和科学研究领域中数据密集型应用越来越广泛,提供透明地访问分布式的、异构的数据源将成为这种应用的关键。提出一种基于网格数据仲裁服务(Grid Data Mediation Service,GDMS)的数据集成系统,它能够把网格中的分布式的、异构的数据源表示成一个逻辑上虚拟的数据源,并设计出了一种灵活的映射模式来描述构建虚拟数据源的过程。
文摘The volume of publically available geospatial data on the web is rapidly increasing due to advances in server-based technologies and the ease at which data can now be created.However,challenges remain with connecting individuals searching for geospatial data with servers and websites where such data exist.The objective of this paper is to present a publically available Geospatial Search Engine(GSE)that utilizes a web crawler built on top of the Google search engine in order to search the web for geospatial data.The crawler seeding mechanism combines search terms entered by users with predefined keywords that identify geospatial data services.A procedure runs daily to update map server layers and metadata,and to eliminate servers that go offline.The GSE supports Web Map Services,ArcGIS services,and websites that have geospatial data for download.We applied the GSE to search for all available geospatial services under these formats and provide search results including the spatial distribution of all obtained services.While enhancements to our GSE and to web crawler technology in general lie ahead,our work represents an important step toward realizing the potential of a publically accessible tool for discovering the global availability of geospatial data.