This section contains examples of Web resources which can be transformed by RDF Cartridges. It also states where additional setup for given cartridges is needed i.e. keys account names etc.

Service based:

  • amazon

    needs: api key
    example: http://www.amazon.com/gp/product/0553383043
    
  • ebay

    needs: account, api-key
    example: http://cgi.ebay.com/RARE-DAY-IN-FAIRY-LAND-ELEPHANT-FOLIO-20-FULL-COLOR_W0QQitemZ140209597189QQihZ004QQcategoryZ29223QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
    
  • flickr needs: api-key example: http://farm1.static.flickr.com/212/496684670_7122c831ed.jpg

  • mbz

    example: http://musicbrainz.org/release/37e955d4-a53c-45aa-a812-1b23b88dbc13.html
    
  • mql (freebase)

    example: http://www.freebase.com/view/en/beta_ursae_majoris
    
  • facebook

    needs: api-key, secret, persistent-session-id
    example: http://www.facebook.com/profile.php?id=841100003
    
  • yahoo-stock

    example: http://finance.yahoo.com/q?s=AAPL
    
  • yahoo-traffic

    example: http://local.yahooapis.com/MapsService/V1/trafficData?appid=YahooDemo&street=701+First+Street&city=Sunnyvale&state=CA
    
  • Bugzilla

    example: https://bugzilla.mozilla.org/show_bug.cgi?id=251714
    
  • SVG

  • OO document

    needs: unzip plugin
    
  • Wikipedia

    needs: php plugin & dbpedia extractor
    example: http://wikipedia.org/wiki/London
    
  • Opencalais

  • iCalendar

GRDDL

  • Google Base (google)

    example: http://www.google.com/base/feeds/snippets/17891817243016304554
    
  • eRDF

  • RDFa

  • hCard

  • hCalendar

  • hReview

  • relLicense

  • XBRL

  • HR-XML

  • DC

  • geoURL

  • Ning

  • XFN

  • xFolk

URN handlers

Table 16.11. URN handlers List

URN handler Sample URI Resource Description Linked Data View Linked Data Graph Needs
LSID urn:lsid:ubio.org:namebank:12292 HTML Representation Linked Data View Data Explorer View none
DOI doi:10.1038/35057062 HTML Representation Linked Data View Data Explorer View Needs hslookup plugin, relevant html, pdf, xml etc. mappers enabled.
OAI oai:dcmi.ischool.washington.edu:article/8 HTML Representation Linked Data View Data Explorer View none

The Virtuoso SPARQL engine (called for brevity just SPARQL below) supports IRI Dereferencing, however it understands only RDF data, that is it can retrieve only files containing RDF/XML, turtle or N3 serialized RDF data, if format is unknown it will try mapping with built-in WebDAV metadata extractor. In order to extend this feature with dereferencing web or file resources which naturally don't have RDF data (like PDF, JPEG files for example) is provided a special mechanism in SPARQL engine. This mechanism is called RDF mappers for translation of non-RDF data files to RDF.

In order to instruct the SPARQL to call a RDF mapper it needs to be registered and it will be called for a given URL or MIME type pattern. In other words, when unknown for SPARQL format is received during URL dereferencing process, it will look into a special registry (a table) to match either the MIME type or IRI using a regular expression, if match is found the mapper function will be called.

Sponger functionality is also exposed via Virtuoso's "/proxy/rdf/" endpoint, as an in-built REST style Web service available in any Virtuoso standard installation. This web service takes a target URL and either returns the content "as is" or tries to transform (by sponging) to RDF. Thus, the proxy service can be used as a 'pipe' for RDF browsers to browse non-RDF sources.

For more information see RDF Sponger Proxy service

To clear cache on all values of HS_LOCAL_IRI of the SYS_HTTP_SPONGE table use:

SPARQL clear graph <A-Named-Graph>;