wurvoc.org - linked open data for Quality of Life

I am proud to announce the official launch of wurvoc.org. Built by the Intelligent Systems Group at Wageningen UR Food & Biobased Research, the goal of wurvoc.org is to serve as a hub for various vocabularies and semantic web services we have developed and are still developing. Many of these vocabularies (modeled in RDF and OWL) have been built using public funding and we feel it important that this information is also publicly available in a way that is open and reusable.

Vocabularies

Currently, wurvoc.org publishes 4 vocabularies:

• The Ontology of Units of Measure models concepts and relations important to quantitative scientific research. It has a strong focus on units and quantities, measurements, and dimensions.
• The Food Additives vocabulary describes substances added to food to improve the flavour, taste, shelf-life, stability et cetera of the food product. Food additives that are approved by EFSA, the European Food Safety Authority are labelled with an E-number.
• The Dairy ontology contains a hierarchy of types of dairy products and provides general information about these products.
• The Drinks vocabulary contains a classification hierarchy of various types of beverages.

Our aim is both to publish more vocabularies and data in the near future, and to extend and improve the current vocabularies: although the data is Open, it is not yet truly Linked in the sense that it has very few relations with external datasets.

Software

We've developed the wurvoc publication platform, a set of REST services on top of the Sesame framework. In line with linked data principles, the platform publishes each vocabulary and each vocabulary term on its own URI. For example, an ontology on food additives is available at http://www.wurvoc.org/vocabularies/food-additives/, and the food additive Pectin is reprsented by http://www.wurvoc.org/vocabularies/food-additives/Pectin.

The platform uses HTTP content negotation to determine the representation format, currently supporting XHTML, RDF/XML, Turtle, N3, NTriples, and TriG (with JSON on the ToDo list).

OUM Web Services

Apart from a vocabulary publication platform, wurvoc.org also offers a number of SOAP-based web services on top of the Ontology of Units of Measure (OUM). These web services provide a number of useful functions, including lookup and matching functions as well as more advanced stuff, such as unit conversion or formulaic consistency checking.

Future plans

We are aiming to publish the publication platform software as open source as soon as possible. Various improvements are also planned, including a SPARQL endpoint and support for JSON.

I'd very much like to hear your comments on what we've brewed sofar, what you think is good and what you think could be better. I encourage you to reuse our linked data (and would appreciate it if you could let us know if you do).
I also plan to keep you up to date on our findings regarding use, performance, and general lessons that we learn after the launch of this project. Watch this space :)

Accessing DBpedia's SPARQL endpoint with Sesame

I'd like to share a tip on using Sesame as a client for SPARQL endpoints. This may be rather trivial to some but perhaps new to others.

We are developing a tool called ROC (Rapid Ontology Construction) (see our paper@ASWC'08), which is a tool that allows domain experts to quickly build a basic vocabulary for their domain, re-using existing terminology whenever possible. How this works is that the ROC tool asks the domain expert for a set of keywords that are 'core' terms of the domain, and then queries remote sources for concepts matching those terms. These are then presented to the user, who can select terms from the list, find relations to other terms, and expand the set of terms and relations, iteratively. The resulting vocabulary (or 'proto-ontology', basically a SKOS-like thesaurus) can be used as is, or can be used as input for a knowledge engineer to base a more comprehensive domain ontology on.

ROC is developed on top of Sesame, and up until now we simply supplied the tool with 'remote sources' by adding data to a locally running Sesame repository. In order to act with the LOD cloud, we obviously needed something a bit less awkward, so I started looking into ways to extend the functionality to be able to query linked open data.

Fortunately, I didn't have to look far, because Sesame actually already supports this: Sesame's client server protocol is a superset the SPARQL protocol. This I already knew, but what I hadn't yet tried was to see if that meant you could use Sesame's client libraries to query any SPARQL endpoint (instead of just connect to a remote Sesame server, which is what it is primarily designed for, after all). And guess what, it turns out that you can!

Here's a bit of code that connects to DBPedia's SPARQL endpoint and fires a query. The idea is simply to reuse Sesame HTTPRepository class, supply the endpoint URL as the server, and specify no repository:

String endpointURL = "http://dbpedia.org/sparql";
HTTPRepository dbpediaEndpoint = 
         new HTTPRepository(endpointURL, "");
dbpediaEndpoint.initialize();

RepositoryConnection conn = 
         dbpediaEndpoint.getConnection();
try {
  String sparqlQuery = 
         " SELECT * WHERE {?X ?P ?Y} LIMIT 10 ";
  TupleQuery query = conn.prepareTupleQuery(SPARQL, query);
  TupleQueryResult result = query.evaluate();

  while (result.hasNext()) {
      ... // do something linked and open
  }
}
finally {
  conn.close();
}

Now, I'm perhaps easily impressed, but to me this was beautifully easy. This makes integrating arbitrary linked open data in most of our Sesame-based tooling (including ROC) completely painless.

VU Dies Natalis: Web and Science

Yesterday, the VU University Amsterdam celebrated its 129th birtday (or Dies Natalis, as universities obviously do not have something as common as a 'birthday'). The theme of this year's celebration was "Web & Science".

The Dies Natalis lecture was delivered by Frank van Harmelen and centered on the question how Web technologies are not just speeding up communication between scientists, but how these new technologies change the way in which we do science itself: is the academic paper, the yardstick of academic achievement, getting out of date, and what other possible yardsticks do we have? Van Harmelen paints a picture of a future landscape of science where data-driven research, empowered by the web, becomes the dominant way of conducting research: the vast amounts of data produced by individual scientists can be shared on the Web and aggregated, integrated, interpreted, and be used to fuel new hypotheses on a scale that was impossible before. In this world, scientific achievement should not just measured by number of published papers or citations, but by number of published data sets or downloads of one's data sets. By using Semantic technologies it may become possible for computers to assist the scientist not just in writing his e-mail and marking up his paper, but in finding relevant data sets, hypotheses, arguments pro and contra, and so on. It would even be possible for the machine to point out contradicting results in two different publications and offer a suggestion for an experiment that shows which result is correct. Science fiction? Perhaps, but van Harmelen argues that at least some of these ideas are closer than we realize.

Highlight of the Dies celebration was the bestowing of an honorary Doctorate to Sir Tim Berners-Lee, not only for his achievement in creating the WWW, but in admiration of his personal commitment to keeping the WWW truly open and universal.
Tim, obviously a bit uncomfortable with the ceremony (which involved him standing in the middle of the podium, wearing a rather peculiar robe, while Guus Schreiber said all sorts of nice things about him), was characteristically humble and gracious in his acceptance, pointing out that all he did was working out a good idea, and that basically the Web came about not just because he had a good idea, but that other people also considered it a good idea and spent tremendous time and effort in making it happen.

The morning session was devoted to the dies symposium, titled "The World Wide Web and Social Development". The focus was very much on how Web technology can be more effectively employed to help developing nations. A highlight was the film and subsequent talk about Yacouba Sawadogo and the efforts in re-greening Africa's drylands, and how more effective communication technology is needed in order to scale up these efforts. Also, a very interesting talk was given about the creation of the WWW Foundation, which focuses on breaking down barriers to effective access to and use of Web technology in less priviliged countries.

All in all, an inspirational day. The beer (specially brewed for the occasion) was not bad either :)