Database Reference
In-Depth Information
7.4.3
S
tep
3: S
pecIfY
Y
oUr
rDfS o
ntoloGY
Merea Maps selects the following classes and properties for its Administrative
Geography RDFS ontology:
Classes: Administrative Area, Country, Region, District, County, City,
and Parish
Properties: hasPlaceName (which is a specialization of foaf:name),
hasArea, spatiallyContains, spatiallyContainedIn, borders,
spatiallyEquivalent.
Imported properties: geo:lat, geo:long, rdf:comment, rdf:label
All the properties can be used by any class, but domain and range are not assigned
to them to avoid overloading the vocabulary unnecessarily.
There are a number of tools available to assist with the development of an RDFS
ontology. Most are also used to build the more complex OWL (Web Ontology
Language) ontologies and hence are described in Chapter 9; however, you may also
wish to look at Neologism,
4
a Web-based tool for creating and managing just RDFS
vocabularies. Note that the RDFS ontology should also conform to Linked Data
principles, namely, each class and relationship term should also be dereferenceable,
so that Linked Data applications can locate their definitions.
A word of warning here: Do not try to add your own terminology to someone
else's namespace, as you will have no control over terms in that namespace and will
not be able to dereference your URIs or make sure that the namespace continues to
exist in the long term. Instead, mint your own URIs and then use
owl:sameAs
to
state their equivalence URIs in the namespace of your interest.
7.4.4
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4: M
Int
Y
oUr
UrI
S
In the previous chapter, we discussed at some length how to create URIs. We
avoid including implementation details such as server names, file format, or port
numbers and choose URIs of the format
http://id.mereamaps.gov.me/
administrative Regions/
,
using the 303 redirect (“slash”) form. Although the
general advice is to use unique keys from the domain if possible, rather than pri-
mary keys from your internal database, no obvious set of unique keys exists for
Merean administrative regions (in the way that ISBN [International Standard Book
Number] numbers are known keys for topics). It may also be that another authority
should really choose the identifiers for administrative areas, for example, the Merea
Boundary Agency that assigns authority to the various administrative areas. But,
to keep our example simple for now, MereaMaps uses the feature ID to generate its
URI. Note that, as suggested previously, separate URIs should be created to describe:
a. The real-world object Ash Fleet Parish
http://id.mereamaps.gov.
