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Emerald Group Publishing Limited
Copyright © 2006, Emerald Group Publishing Limited
A Semantic Web Primer
G. Antoniou and F. van Harmelen,MIT Press,Cambridge MA2004238 pp.,ISBN: 0-262-01210-3
Spinning the Semantic Web: Bringing the World Wide Web to its Full Potential
Edited by D. Fensel, J. Hendler, H. Lieberman and W. Wahlster,MIT Press,Cambridge MA2003479 pp.,ISBN: 0-262-06232-1
Keywords: Internet, SemanticsReview DOI: 10.1108/00220410610642138
The semantic web, a concept pioneered by Tim Berners-Lee, instigator of the world wide web itself, is a vision of a web which would allow greatly improved access to its information. This would be achieved by representing its content in ways which are readily processable by machine. It is semantic in the sense that the significance of the components of web pages – title, creator, subject descriptor, etc. – would be made explicit, while at the same time more sophisticated content description would be available. The semantic web initiative, which sees this meaning-rich environment evolving from the existing web, has been supported by several organisations, including the world wide web consortium, the European Union, through its Sixth Framework Programme, and the US government’s DARPA projects.
Despite its evident importance to anyone engaged in library/information work, or many related areas of documentation, the details of the semantic web are often not clearly understood in our environment. This may be partly because of the sometime opaque terminology surrounding the important concepts of this initiative, and partly because of a lack of accessible material (accessible in an intellectual sense; many semantic web documents are readily available from the web itself, but difficult to comprehend for someone who does not appreciate their context). These two books from MIT Press are good examples of what is needed to redress this situation. Despite their publication dates, they explain the basic concepts and technologies in a way which is little dated.
The text by Antoniou and van Harmelen should be particularly useful in this respect. Clearly written, and including a good number of helpful examples, it focuses on the core concepts and technologies needed to make the semantic web a reality. The authors take these to be: XML, the language for structuring web documents; RDF and RDF Schema, data models and associated vocabulary for assigning meaning to these documents; OWL, an ontology language giving a greater power of expressing knowledge than RDF; and the various rules of logic and inference which can be used to process semantic web knowledge. These are all explained with unusual clarity, and supported by helpful examples.
Commendably, and unusually, Antoniou and van Harmelen are aware of vocabularies such as MeSH, Embase, the Unified Medical Language System, the Getty Thesaurus and so on, and illustrate the ways in which they may contribute to semantic web applications. They describe thesauri as “very lightweight ontologies”, presumably because of their lack of formal elements for machine processing. Taxonomies are also categorised as simple ontologies, as is Dublin Core, so that one feels that a more discriminating treatment is needed (for example, Gilchrist, 2003). This point, however, should not detract from the credit due to these authors for showing relevance of “traditional” knowledge organisation tools to newer developments.
The focus on these few essential tools does mean that some arguably relevant things are omitted. There is no mention, for example, of topic maps, an alternative to RDF Schema for incorporating controlled vocabularies.
These, however, are quibbles. This is an excellent book, which should be read by anyone from a documentation background who is unclear as to exactly how their concepts and expertise fit into this new development.
Those seeking a more in-depth treatment of some of these issues will find it in the volume edited by Dieter Fenschel and his colleagues. The 15 contributed chapters cover a wide variety of material, often at a high level of detail, and requiring considerable prior understanding. Several chapters deal with ontologies in detail, and will be helpful to those seeking to know just what this much-used term means in practice. Deborah McGuiness’ chapter “Ontologies come of age” is particularly helpful.
David BawdenCity University, London, UK
Gilchrist, A. (2003), “Thesauri, taxonomies and ontologies – an etymological note”, Journal of Dcumentation, Vol. 59 No. 1, pp. 7–18