最近几年来，地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持，如城市管理、区划、环境整治等等，地理信息成为信息时代重要的组成部分之一； “数字地球”概念的提出，更进一步推动了作为其技术支撑的GIS的发展。 与此同时，一些学者致力于相关的理论研究，如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面，并且这两个方面构成了相互促进的发展过程。
RDF uses Web identifiers (URIs) to identify resources.
RDF uses attributes and attribute values to describe resources. RDF uses Web identifiers to identify things and describes resources by attributes and attribute values. Interpretation of resources, attributes, and attribute values: 资源 Is anything that can have a URI, such as “ https://www.runoob.com//rdf ”” 属性 Is a resource with a name such as “author” or “homepage” 属性值 Is the value of an attribute, such as “David” or “ https://www.runoob.com/ ”” (note that an attribute value can be another resource) The following RDF document describes the resource “ https://www.runoob.com//rdf ”: The above is a simplified example. The namespace is ignored. A combination of resources, attributes, and attribute values can form a 陈述 (called declarative 主体 、 谓语 And 客体 ). Please take a look at some specific examples of statements to deepen your understanding: Statement: “The author of https://www.runoob.com//rdf is David.” The subject of the statement is: https://www.runoob.com//rdf The predicate is: author The object is David Statement: “The homepage of https://www.runoob.com//rdf is https://www.runoob.com/ ”. The subject of the statement is: https://www.runoob.com//rdf The predicate is: homepage The object is https://www.runoob.com/ RDF resources, attributes, and attribute values ¶
RDF statement ¶