Were are all the Semantic Web presentations ?

A follow-up to my previous LODr introduction post, and as you might guess with the title, one more way to show the value of RDF-based applications in general. Or more precisely, open-RDF-based and LOD-compliant:

• By open-RDF-based, I mean using RDF but also publishing it, eitheir through a SPARQL endpoint, Semantic sitemaps or RDFa. What I want to focus on here is that using RDF ‘inside-only’ doesn’t make your service be part of the Semantic / Linked Data Web, while it can indeed be considered as Semantic-Web based - I hope that’s clear enough. If you don’t expose anything, you can have the better RDF infrastructure that you want, you will still be a Web-of-Documents application. (Some related thoughs here);
• Regarding LOD-compliance, I refer to reusing or interlinking existing resources in order to benefit from it within your application. The value of your service can then reside not only on the data you provide, but on the way you interact with - and reuse - other datasources. Moreover, this can also concern corporate environments.

What I want to stress in that post is how such applications can become components of a general infrastructure (the Semantic Web itself) that will provide new services to end-users. Especially, regarding LODr, it lets users interlink popular Web 2.0 content to Semantic Web resources and such interaction can then be used for data discovery. For instance, the following query will retrieve all Slideshare presentations related to the Semantic Web, i.e. linked to a resource that is itself linked to the SW category in DBpedia. This query involves various vocabularies, as SIOC (to retrieve the item), FOAF (its author), the Tag Ontology (its tags), MOAT (tags meanings) and a DBpedia URI as an entry point to find related topics.

SELECT DISTINCT ?item ?author ?date ?tag ?meaning
WHERE {
  ?item a sioc:Item ;
  dct:created ?date ;
  sioc:has_space <http://slideshare.net> ;
  foaf:maker ?author .
  [] a tags:RestrictedTagging ;
    tags:taggedResource ?item ;
    tags:taggedWithTag [
      tags:name ?tag .
    ] ;
    moat:tagMeaning ?meaning .
  ?meaning ?p <http://dbpedia.org/resource/Category:Semantic_Web> .
}
ORDER BY DESC(?date)
LIMIT 5

You can browse the answer here, formatted in HTML.

Of course, the URIs that you can use in LODr and with MOAT in general are not restricted to DBpedia ones. You can use URIs defining some of your friends, conferences you attended, etc. Consequently, those URIs can be used in queries patterns, as well as other interlinked URIs. For instance, the following one will retrieve all pictures from Flickr linked to an event that happened in Tenerife, and in that case it will use the ESWC2008 URI, going through some Geonames data:

SELECT DISTINCT ?item ?author ?date ?tag ?meaning
WHERE {
  ?item a sioc:Item ;
  dct:created ?date ;
  sioc:has_space <http://flickr.com> ;
  foaf:maker ?author .
  [] a tags:RestrictedTagging ;
    tags:taggedResource ?item ;
    tags:taggedWithTag [
      tags:name ?tag .
    ] ;
    moat:tagMeaning ?meaning .
  ?meaning foaf:based_near <http://sws.geonames.org/2522437/> .
}
ORDER BY DESC(?date)
LIMIT 5

Answer

Finally, while all those queries involve the lodr.info endpoint, each LODr intance comes with its own triplestore (and related endpoint), so that one can add some more RDF in it for advanced mash-ups. And as it also provides RDFa and semantic sitemap support, semantic web crawlers and indexes as SWSE or Sindice can also consume it and then deliver it when you look for a particular URI.

Comments

• About

  This is the personal website of Alexandre Passant, PhD student in the Semantic Web and Social Software area.

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  • SIOC goes OWL-DL
  • Were are all the Semantic Web presentations ?
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