What Is It?

A data virtualization service that transforms data hosted in a variety of data spaces and formats into standards compliant Linked Data Objects for uniform access, integration and management.

The underlying technology is Virtuoso's in-built Linked Data Middleware (aka Sponger) that uses URLs as data source names for its powerful data ingestion and transformation services that result in highly navigable Linked Data Object graphs.

Post transformation, each Data Object is endowed with a dereferenceable identifier (Name) that resolves to its actual representation via its URL (Address). The Sponger then re-presents Data Object descriptions via HTML documents (the default behavior) or in a variety of raw data graph forms that include: CSV, N-Triples, Turtle, N3, RDF/XML, JSON, CXML, OData (Atom and JSON) etc.

Why Is It Important?

It provides an unobtrusive solution for creating, discovering, meshing, and sharing structured Linked Data sources exposed via the Web.

How Do I Use It?

Web Users & User Agents

Methods of exploiting Sponger's services from your browser include:

Bookmarklet

Simply drag the following bookmarklet links to your browser's bookmarks toolbar:

Browser URL input

To dereference the description of a Web-addressable resource via your browser simply type in one of the following URL patterns:
  • HTML - http://{virtuoso-host}/about/html/{URIscheme}/{authority}/{local-path}
  • RDF - http://{virtuoso-host}/about/data/{format}/{URIscheme}/{authority}/{local-path}
where format is one of xml, n3, nt or ttl.
Examples

OpenLink Data Explorer Extension for Firefox

Simply go to the OpenLink Data Explorer Home Page, download the extension, and then whenever you encounter a page of interest, use the main or context-menu options labeled "Describe Page" or "View Linked Data" to obtain Web addressable resource descriptions in HTML or RDF.

Alternatively, use the following bookmarklet:

Web Publishers

Simply include the following in the <head> section of your (X)HTML page (static or dynamically generated):

<link rel="describedby"
title="RDF Model-based Metadata in your desired format 
(e.g. xhtml, n3, turtle, rdf/xml etc)."
type="{required mimetype}"
href="http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}"
/>

You can optionally notify the PingTheSemanticWeb (PTSW) web service each time you generate a Linked Data graph. PTSW is used by crawlers or software agents to know where the latest Linked Data documents can be found and when they have been updated.

Web Application Developers

Using your host operating system of development language embedded variants of cURL, you can exercise all the dereferenceable proxy/wrapper URIs generated by this service, along the following lines:

HTML+Microformats:

  • curl -I -H "Accept: text/html"
    http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}

HTML+Microdata:

  • curl -I -H "Accept: text/html"
    http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}

HTML+RDFa:

  • curl -I -H "Accept: text/html"
    http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}

XHTML+RDFa:

  • curl -I -H "Accept: application/xhtml+xml"
    http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}

JSON:

  • curl -I -H "Accept: application/json"
    http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}
  • curl
    http://{virtuoso-host}/about/data/json/{URIscheme}/{authority}/{local-path}

Microdata/JSON:

  • curl -I -H "Accept: application/microdata+json"
    http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}

JSON-LD:

  • curl -I -H "Accept: application/ld+json"
    http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}

Notation 3 (N3):

  • curl -I -H "Accept: text/n3"
    http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}
  • curl
    http://{virtuoso-host}/about/data/n3/{URIscheme}/{authority}/{local-path}
  • curl -I -H "Accept: text/turtle"
    http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}
  • curl
    http://{virtuoso-host}/about/data/ttl/{URIscheme}/{authority}/{local-path}

RDF/XML:

  • curl -I -H "Accept: application/rdf+xml"
    http://{virtuoso-host}/about/id/{URIscheme}/{authority}/{local-path}
  • curl
    http://{virtuoso-host}/about/data/xml/{URIscheme}/{authority}/{local-path}

Discover the Web's Linked Data Space Dimension

Make your profile or other documents of interest your starting point!

Click on an icon to sponge your social network data Help icon

Facebook

The Sponger can be configured as a Facebook App. Sponging of your Facebook profile then follows these steps:

  • The Sponger will request access to your Facebook profile. If you authorize access, Facebook will grant an OAuth access token.
  • On receipt of the access token, the Sponger notes your Facebook ID
  • In the authorization confirmation dialog, the Sponger provides URLs for sponging your profile and viewing the generated Linked Data objects.

You can revoke access by the Sponger at any time.

Examples

Transform a document or Web service into Linked Data!

Enter the URL to sponge:

Querying Your Linked Data

Full Text Search & Precision Find

Perform traditional full text pattern search, or Linked Data enhanced precision find, against sponged data via: http://{virtuoso-host}/fct

Using SPARQL

Linked Data may be queried using the SPARQL query language, by simply pointing your browser at:

  1. SPARQL Query-By-Example:
    http://{virtuoso-host}/isparql
  2. Basic SPARQL Endpoint:
    http://{virtuoso-host}/sparql