Abstract
The Semantic Web (SW) and Geospatial Semantic Web (GSW) are considered the next step in the evolution of the Web. For most non-Web specialists, geospatial information professionals, and non-computer-science students these concepts and their impacts on the way we use the Web are not clearly understood. The purpose of this chapter is to provide this broad audience of non-specialists with a basic understanding of: the needs and visions driving the evolution toward the SW and GSW; the principles and technologies involved in their implementation; the state of the art in the efforts to create the GSW; the impacts of the GSW on the way we use the Web to discover, evaluate, and integrate geospatial data and services; and the needs for future research and development to make the GSW a reality. A background on the SW is first presented to serve as a basis for more specific discussions on the GSW.
TopBackground On The Characteristics Of And The Need For The Semantic Web (Sw)
There are numerous definitions of the SW. Yu (2007) reports that there are 290 websites containing the term SW and providing some sort of definition of it; a search in Google for the “Semantic Web” term in Web documents and scholarly works returns 15,300,000 pages (Hepp, 2006). Passin (2004 pp. 3-4) provides several definitions that vary based on the approach taken to analyze or implement the SW. Instead of providing another definition, let’s first consider the current limitations of the WWW and why we need an evolution toward the SW and the GSW.
The original intent of the Web was to create a system where information could be linked. The idea was to define a few basic, common rules or protocols that would allow one computer to talk to another located anywhere. For the Web, those elements were (in decreasing order of importance): Universal Resource Identifiers (URIs), the Hypertext Transfer Protocol (HTTP), and the Hypertext Markup Language (HTML) (Berners-Lee, 2000). After going through several evolution stages the Web has evolved into a complex knowledge space where service agents (software that automates processes, acts independently on behalf of the user and has some decision making capabilities) and Web 2.0 technologies help humans to search and organize information (Ding & Xu, 2007).
Key Terms in this Chapter
Ontology: Is a representation of a set of concepts within a domain and the relationships between those concepts. In other words, an ontology defines the vocabulary of a domain.
Geospatial Data and Information: Are data and information that identify the geographic location (using precise scientific coordinates), and the characteristics of natural or constructed features and boundaries on the Earth.
Web Services: Are self-contained, self-describing, modular applications that can be published, located, and dynamically invoked across the Web.
Semantic Web: is an extension of the current Web in which data and information on the Web are defined and linked in a way that it can be used by computers not only for display purposes, but for automation, integration, and reuse of data across various applications. The Semantic Web allows computers to make more sense of the information on the Web with the result of facilitating better cooperation between computers and people.
Geoprocessing: Is the manipulation of geospatial data and the analysis of these data to derive information. Geoprocessing is used to generate high-quality data, perform quality control checks on data, and undertake modeling and analysis.
Interoperability: Is the ability for a system or components of a system to provide information portability and interapplication cooperative process control. This means software components operating reciprocally to overcome tedious batch conversion tasks, import/export obstacles, and distributed resource access barriers imposed by heterogeneous processing environments and heterogeneous data.
Geospatial Semantic Web: Is an augmentation to the Semantic Web that adds geospatial abstractions, as well as related reasoning, representation and query mechanisms.