Semantic Web at Opera

With the new release, there is a new feature that you can find on your account page:

I'm allowing you to map your tags to a controlled vocabulary. For the time being, it is Wordnet, but I can include a number of such things. The main reasons I used it is that it is allready quite widespread, is organised in subclasses and superclasses (e.g. it knows that a dog is an animal, and that the W3C is standardising a Semantic Web representation of it.

Up to recently, people have classified their stuff into a set of rigidly defined categories, so-called taxonomies. The advantage of having such a rigid set, are that the meaning of each category is clearly defined, you avoid problems such as one person using "dog" while another uses "dogs", and you can organise your categories into hierarchies such as Wordnet, which makes it very usable for a number of applications.

The downside is that it is also very difficult to know the whole vocabulary well enough so that you can classify things in the right way. Thus, it has remained the domain of professional librarians mainly.

Enter "folksonomies", or "tags". Tags have become enormously popular, as it is easy to use. You just name a tag for yourself and use it. You can the find your pictures easily, if people are using the same tag for the same thing, you can also find it to find similar things. But, and a big but, people often use the same tag for a lot of different things. You can perhaps find some related items, but it is often not very reliable, and since everyone would need to maintain their own tag hierarchy, you can't figure out from a picture tagged "dog" that it also depicts an animal.

Now, you can say explicitly what you mean by mapping your tag to any of the suggested Wordnet meanings. If you do, we get the advantages of both these approaches.

For the time being, we don't do a lot with it, and it is only mapped to Wordnet, but in the future, we hope to enable exactly the kind of searches above, "give me all pictures of animals" will include pictures tagged "dog", "cat" etc.

There will also be many more vocabularies. For example, we intend to use tags to allow you to set any Content Label available. We can also let you map tag with a person, when, for example your picture depicts a person.

With this, we intend to make tags the simple way to annotate things on the Semantic Web. Try it out! On the top of your page, you'll see a "My Account", and it is a "Tags" page underneath.

With the latest update of the Opera Community, a new field in the user Preferences came along. You may now enter the URL of an RDF document hosted somewhere else. Of course, that somewhere else may well be in your files directory here on the Opera Community. For example, take a look at how my FOAF here has a line looking like this:

  <rdfs:seeAlso rdf:resource="http://www.kjetil.kjernsmo.net/foaf.rdf"/>

which is a reference to my personal hand-coded RDF documented hosted on my home machine.

First of all, this allows you connect the data we turn into RDF for you here at the Opera Community with data you make available yourself. Next, it makes the Opera Community much more friendly to web-spiders, or Scutterers like they are called in the RDF world. Finally, I plan to retrieve the files referenced here and put the data into the SPARQL engine, so that they can be queried here.

Now, go to your Preferences, and edit your profile, there you will find a RDF field. Enter the address of an RDF document there!

I'd like to point out that Jim Ley, an SVG and Semantic Web guru, has created a widget called Widgnaut. It can be used to explore the social networks of the Opera Community, by clicking on people. It works similarly to FOAFNaut, by the same author.