No, these aren’t the necessary precursors for a conspiracy theory about the moon landings, but three of the topics touched upon at the first VoCamp, which took place recently in Oxford. VoCamps are events where motivated individuals can come together and spend some dedicated time creating vocabularies/ontologies for describing data on the Web.

You may have heard of these vocabulary things before. Two popular examples that have been around for some time and are in widespread usage are FOAF (as in Friend of a Friend), for describing people and who they know, and SIOC, for describing the contents of ‘social media’ sites such as blogs and discussion fora. But why do we need more vocabularies, and why do we need VoCamps?

We need more vocabularies because people are increasingly motivated to share their data online, and need some way of describing the data itself in a structured fashion. If people use the same vocabularies when describing data of the same type, or at least some of the same terms, it makes sharing and integrating those data sets much easier. For example, imagine you and I both run online shops selling sports equipment, and we want to describe the stock we hold, if we use the same vocabulary to describe that stock data then anyone wanting to cross search our two shops will benefit by not having to map my data structure to yours — we’ll have saved them the job by converging on the same vocabulary from day one.

At this point in time there just aren’t enough vocabularies around to describe the wealth of data in the world. Left to their own devices people will simply create ad-hoc vocabularies which do little to aid data sharing. It’s for these reasons that we need VoCamps, where people can put day-to-day distractions to one side and concentrate on creating technically sound vocabularies in domains that interest them, according to some of the best practices in the field.

VoCampOxford2008 was the start of this process. I used the time to work with Ian and others on a vocabulary/ontology for describing Whisky. Leigh created his Space Flight vocabulary — not just a flippant bit of fun, but a crucial component in his desire to make NASA data more widely accessible and easily archived. Other groups at VoCampOxford2008 worked on a vocabularies for describing IRC discussions, evidence, discourse, participation, votes, journeys and scientific data. See this page for more information on the vocabs we created.

Now, while some people would no doubt argue that whisky and space flight constitute the two most important topics around, there’s still some way to go in creating the rich ecosystem of vocabularies required for a Web of data. That’s why the second VoCamp will take place in Galway, Ireland in late November. Anyone interested in getting their hands (metaphorically) dirty and creating some vocabs should register now before the event fills up — it’s free. Given the location I’ll have to spend a little time in Galway refining the Whisky ontology, but no doubt there’ll be plenty of scope for creating vocabularies in other areas. I may even attempt a vocabulary for describing conspiracy theories, but I imagine that no-one would be able to agree on the details!

Semantic Web for the Working Ontologist Effective Modeling in RDFS and OWL is a new book authored by Dean Allemang and Jim Hendler. I can offer a quick summary by teasing apart the title. For starters, the Semantic Web it discusses is generally in line with the current consensus view of the developer community, though with a lean in the direction of the ‘O’ word. The emphasis in the book is very much on Working and Modeling. It is practically oriented, and while it covers most of the technologies associated with the Semantic Web, its focus is on how to describe things using RDF, RDFS and OWL.

There’s a serious shortage of approachable books in the Semantic Web space – if you check the ESW Wiki list, there are only a handful that aren’t heavy duty academic works. Aside from the issue of convincing publishers there’s a market for such material (a problem that’s no doubt evaporating), there’s the difficult problem of what to write about. In the 2003 book Practical RDF, Shelley Powers used the parable of the Blind Men and an Elephant to suggest how RDF has many different aspects and can mean different things to different people – and RDF is just one Semantic Web technology (though arguably the most important). What’s more the elephant changes over time and is lavishly decorated: while the core standards solidified in 2004, since then we’ve seen various auxiliary specifications come along: the SPARQL query language, Turtle/N3 syntax, RDFa, GRDDL and so on. Ideas on best practices have also developed considerably over the years. This book is scoped to modeling with RDF, RDFS and OWL, and covers that ground admirably.

Allemang and Hendler are known experts, well-versed in the subject matter, but what’s more they have spent considerable time teaching courses on the Semantic Web, and this experience shows. The writing is clear and the book’s full of well-illustrated examples, along with a short but very handy FAQ at the end. The practical side is hinted at in their decision to devote significant space to the SKOS Simple Knowledge Organization System and FOAF Friend of a Friend vocabularies. The syntax used throughout is N3/Turtle, which makes a refreshing change from the eyestrain of RDF/XML.

There aren’t any programming (as in running code) examples, and the coverage of things like HTTP and the use of these technologies on the Web is really confined to illustrated prose. I must admit I was disappointed by the limited coverage of SPARQL, I do think this has relevance to modeling decisions. Given the rise of Linked Data in the wild, I would also have expected maybe a chapter devoted specifically to this approach (the ideas are all there in the text, but they don’t jump out).

On the other hand the coverage of reasoning with Semantic Web languages is excellent, material that can be very hard to get a handle on is here presented in an easily digestable form. Similarly the fundamental theory is explained in simple terms without recourse to arcane notation, and common misconceptions around the Semantic Web are disposed of without malice.

Contents

1. What is the Semantic Web?
2. Semantic Modeling
3. RDF – the Basis of the Semantic Web
4. Semantic Web Application Architecture
5. RDF and Inferencing
6. RDF Schema Language
7. RDFS-Plus
8. Using RDFS-Plus in the Wild
9. Basic OWL
10. Counting and Sets in OWL
11. Using OWL in the Wild
12. Good and Bad Modeling Practices
13. OWL Levels and Logic
14. Conclusions
15. Frequently Asked Questions

RDFS-Plus is RDFS with the addition of some handy bits of OWL (IFPs etc).

In conclusion, this is an approachable book for anyone with interest in the field, and gives excellent coverage of the Semantic side of the Semantic Web, as it pertains to modeling the real world. With the caveat that this is the scope of this book, I’d personally strongly recommend it. I do intend to read this book cover to cover thoroughly, it is insightful writing, and as an occasional OWL user I’ll be keeping it on hand for the recipes.

See also: Henry’s [p]review