Saturday Dec 15, 2007

James Gosling has a foaf name

And so does Tim Bray, Greg Papadopoulos, Jonathan Schwartz, Sun Microsystems, and Java. All thanks to the great work of the DBPedia people, a loose network of highly skilled distributed self selected avant garde force de frappe, who are extracting all the metadata possible from Wikipedia and making it available as hyperdata, ready to be linked to. :-)

You can browse their information on the web, or with the Tabulator generic data browser which will merge information it finds into one large graph as you explore it. As a result of this I can now add Tim Bray and James Gosling to my foaf file (foaf icon), by adding the following N3 statements:

:me foaf:knows [ = <http://dbpedia.org/resource/James_Gosling>;
                    a foaf:Person;
                    foaf:name "James Gosling" ],
               [ = <http://dbpedia.org/resource/Tim_Bray>;
                    a foaf:Person;
                    foaf:name "Tim Bray" ] .

It is worth looking at how DBPedia works. http://dbpedia.org/resource/James_Gosling is now a Universal Resource Identifier for James Gosling. You cannot fetch James because he is not an information resource, ie, he is not a document, though he is very resourceful, and full of interesting information. You can tell that James is not an information resource because you can't copy him easily. So when you do an HTTP GET on that URI you get the following:

hjs@bblfish:0$ curl -I http://dbpedia.org/resource/James_Gosling
HTTP/1.1 303 See Other
Date: Sat, 15 Dec 2007 17:57:54 GMT
Server: Apache-Coyote/1.1
Vary: Accept,User-Agent
Location: http://dbpedia.org/page/James_Gosling
Content-Type: text/plain
Content-Length: 90

ie you get a redirect to the page about James Gosling. This is because curl by default asks for the html representation of resources. Had you sepecified that you wanted the machine readable rdf/xml representation you would get a redirect to another resource:

hjs@bblfish:0$ curl -I -H "Accept: application/rdf+xml" http://dbpedia.org/resource/James_Gosling
HTTP/1.1 303 See Other
Date: Sat, 15 Dec 2007 18:01:10 GMT
Server: Apache-Coyote/1.1
Vary: Accept,User-Agent
Location: http://dbpedia.openlinksw.com:8890/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&query=DESCRIBE+%3Chttp%3A%2F%2Fdbpedia.org%2Fresource%2FJames_Gosling%3E
Content-Type: text/plain
Content-Length: 210

Here you get a redirect to a SPARQL query to DESCRIBE James Gosling. To get the full content, in N3 try:

hjs@bblfish:0$ curl -L -H "Accept: text/rdf+n3" http://dbpedia.org/resource/James_Gosling 

the -L flag follows all the redirects...

Monday Oct 08, 2007

Open Data Licences

The amount of Open Data is growing fast. The idea that data may need protection in an Open Society is bizarre enough, but in Europe at least a whole set of laws have been put in place for this purpose. For those who wish to add data to the Commons, so that it may better contribute to the value of the network as predicted by Metcalf's law, current Open licences will not do it seems. This is, as I understand, because copyright licenses do not cover data well, since a set of relations can be serialized in any number of ways: order does not matter, it is easy to refactor data, or combine it with other data. (I wonder then why this was not a problem for source code?)

To help resolve these issues, Talis, a Leading Semantic Web company, helped fund research into this area which resulted in the Open Data Licence project, which is now seeking feedback on their proposals. From my quick reading of it this license seems to have a gnu feel to it, but I may be wrong.

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