Database Reference
In-Depth Information
This proposal had the full backing of President Clinton and recognized that GI
needed to be part of a national infrastructure (although why just GI was singled out
is unclear). All the ideas for an SDI were there, as was the political will; only the
technology and the standards to make it happen were missing.
The United States was not alone, and other countries, including many in Europe, also
began developing formal SDIs, as did emerging economies such as India. The Euro-
pean Union is currently developing INSPIRE (EU Parliament Directive 2007/2/EC),
a European-wide SDI for environmental data.
SDIs are standards based and model spatial data around maps and features.
Features conform to the OGC Simple Feature Model and are encoded for transport
using GML. Mapping (essentially raster images) is served using WMS-compliant
servers and features via WFS servers. Most SDIs also try to define the data (always
government data) covered by the SDI and do so as a series of GIS style layers. Thus,
most SDIs include a transport layer, a land use layer, a hydrology layer, and so on. As
the standards and technology have developed, so has it become easier to achieve the
aims of an SDI. However, this has also exposed other difficulties that SDIs have not
fully resolved. The most significant of these have been the lack of tools to support
data integration, the difficulties of addressing the semantic differences between
datasets, and organizational inertia. Governments have responded to semantic dif-
ferences by attempting to construct consensual standards that agree on a particular
set of semantics. Such attempts tend to be long and drawn out and, as we shall see,
are not in line with the principles of the Semantic Web or indeed the nature of the
Web as a whole.
3.5.2 Gi: a h
istory
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oinCidenCe
The growth of GI within a professional context is not the only story to tell. GI,
particularly in the last few years, has been significantly influenced by an amateur
perspective. Two things have enabled this to happen: the establishment of Web-based
mapping services that provided a resource to be used by the general population and
the development of Web 2.0, where Web users became authors as well as readers.
As has been mentioned, it became easier to integrate mapping applications into
Web sites, but initially this was usually hosted by an organization that placed map-
ping on its Web site. Web users then passively accessed the site to view the mapping
and associated information. This was after all very much the way we understood
the Web: The Web was a place where organizations published and the general public
consumed. In the early to mid-2000s, this simple setup gave way to increased com-
plexity as it became easier for ordinary people to publish data. The key development
was the provision of tools on Web sites that allowed the user to update the site and
indeed to create the content. One of the earliest examples was the comments and
reviews on Amazon.com, but there are many other examples, such as wikis, where
users collaboratively edit content; blogs, where individual users chronicle their own
thoughts; social bookmarking sites like Delicious and Digg; or tools like Really
Simple Syndication (RSS), which allows feeds from multiple sites to be collated
in one place. This trend toward user-generated content became known as Web 2.0.
The use of the Web 2.0 label indicated that it was felt that this advance really was
