Semantic Web
associated bibliographic information, whilst the relationships between individual tests, experiments, and their results can also be linked. Linking things in this way enables computers to pull up relevant data and results from all over the internet. However, the power of RDF triples goes
beyond linking specific words or phrases. Any of the parts of an RDF triple can be replaced with URIs, which are unique to a particular thing or concept. In the simple triple example ‘David likes apples’, it would not be clear to a machine whether ‘apples’ refers to the fruit or the computer, leading to ambiguity and irrelevant terms appearing in a semantic search. The distinction can be achieved by replacing the literal ‘apples’ with a URI to either the fruit (dbpedia. org/page/Apple) or the computer company (
dbpedia.org/page/Apple_Inc.). The use of URIs also allows established ontologies and vocabularies to be built. For instance, when describing a website, it is possible to make use of both Dublin Core metadata elements for describing resources and Library of Congress Subject Headings.
Using established ontologies (or devising and making public your own ontologies if none exist already in your field) helps computers to be able to find all the related information. See the box (left) for examples of how RDF triples are written.
‘As consumers of information, librarians
need to be aware of the range of data that is being published online and the tools available’
RDF is important to librarians as both
publishers and consumers of information. Libraries are responsible for the publishing of a wide variety of information on web pages, in catalogues, and increasingly in institutional repositories of both journal articles and data sets. The value of this information can be increased by making it machine readable, and connecting it
to otherwise unconnected data sources. At the simplest level it may be including RDFa markup in staff contact pages, or at a more advanced level making the whole catalogue available in RDF and connecting it to other sources such as the Library of Congress. As consumers of information, librarians need to be aware of the range of data that is being published online and the tools available to make use of it, from browser toolbars for extracting event information and sending it straight to their calendar, to interfaces for querying the data stored in triplestores. As has already been seen in the area
of Web 2.0 mashups, when data is made publicly available, it is used in a multitude of ways unthought-of by the original organisation. The same will be true as an increasing amount of information is made available using RDF.
David Stuart is an independent web analyst and consultant and honorary member of the Statistical Cybermetrics Research Group at the University of Wolverhampton, UK
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