Database Reference
In-Depth Information
The topic does not attempt to provide a very detailed implementation guide,
however: It is not a hard-core coders' manual. Instead, it is an introduction to the
topic with an emphasis on getting the approach right at the design level. Nonetheless,
the topic introduces all the main technologies and provides reasonably detailed
descriptions of the languages and syntaxes that are associated with the Semantic
Web and Linked Data in particular.
The terms
Semantic Web
and
Linked Data
lead one to believe that these technolo-
gies are only for the Web, but this is not the case; more and more people are also
turning the technologies inward and using them within their organizations as well
as to publish data externally on the Web. These technologies are more than anything
about data integration; there is a big clue to this in the term
Linked Data
. GI also has
an important role to play in integrating data. As we discuss further in the topic, the
very characteristics that make these technologies suitable for data integration also
make them good at adapting to change—something that all organizations face and
with which traditional ITs struggle to cope. The topic is therefore also aimed at those
for whom better ways to structure their organization's data are also a driving force,
as well as for those whose aim is to publish their data on the Web.
By the end of the topic, you will have a good understanding of the nature of the
Semantic Web, Linked Data, and GI. You will be able to think about how to model
information, especially GI, in a way suitable for publication on the Linked Data
Web and which is semantically described. Technically, the topic will have provided
an overview of the key languages that you will need to master (RDF, the Resource
Description Framework; OWL, Web Ontology Language; and SPARQL—the recur-
sive acronym for SPARQL Protocol and RFD Query Language), and you will under-
stand the process required to publish your data. Last, you will have been introduced
to some of the tools required to store, publish, interlink, and query Linked Data.
1.2 GEOGRAPHY AND THE SEMANTIC WEB
Before descending into too much detail, let us start by introducing the terms
Geographic Information
,
Semantic Web
, and
Linked Data
.
1.2.1 G
eoGraphic
i
nformation
Put simply, GI is any data that has a geographic aspect, although in many cases
the geographic component may be quite small or viewed as only peripheral to the
main focus. To those whose first encounter with GI has been through location-based
applications such as Google Maps, it may not be immediately apparent why GI has
traditionally been seen as a distinct class of information. Special systems to handle
geographic systems have been around since the early 1960s. At first, these were all
bespoke systems, as indeed were most computer applications of the time, although
by the late 1960s to early 1970s commercial off-the-shelf Geographic Information
Systems (GIS) were becoming available. The reason for the emergence of this dis-
tinct class of software GI has been attributed to the need to perform specialist com-
putations involving geometry. For example, the one-dimensional indexes suitable
for mainstream databases had to be supplemented with two-dimensional spatial
