Linked Data

#me

• @bertails
• works at W3C, we do Web-related stuff :-)
• do Linked Data, and a big soon-to-be-released project in Scala
• slides available at http://www.w3.org/2012/Talks/bertails-devoxxfr/linked-data/

A story of the Web

Data on the Web and Web of Data

Bringing data in the markup

Schema.org

http://schema.openspring.net/recipe/apple-pie

http://www.google.com/webmasters/tools/richsnippets

Data formats

• RDFa
• Microdata
• Microformat

Microdata

<div itemscope itemtype ="http://schema.org/Movie">
  <h1 itemprop="name"&g;Avatar</h1>
  <div itemprop="director" itemscope itemtype="http://schema.org/Person">
  Director: <span itemprop="name">James Cameron</span> (born <span itemprop="birthDate">August 16, 1954)</span>
  </div>
  <span itemprop="genre">Science fiction</span>
  <a href="../movies/avatar-theatrical-trailer.html" itemprop="trailer">Trailer</a>
</div>

Microformats

http://microformats.org/

<span class="vevent">
 <span class="summary">The microformats.org site was launched</span>
 on <span class="dtstart">2005-06-20</span> 
 at the Supernova Conference 
 in <span class="location">San Francisco, CA, USA</span>.
</span>

Some deployment numbers

Source: WebDataCommons.org, Febuary 2012

• 13% of all HTML pages contain structured data
• 1.4 billion HTML pages parsed (Common Crawl corpus)
• 188 million pages contained Microformat, Microdata, RDFa data

Source: Yahoo! Research, January 2012

• 30% of all HTML pages contain structured data
• 3.2 billion HTML pages parsed (Bing Crawl corpus)
• 973 million pages contained Microformat, Microdata, RDFa data

Web API (REST style) 1/2

/cheese/

• POST → create new resource
• GET → list all
• PUT → update in bulk
• DELETE → remove all

/cheese/1234

• POST → ?
• GET → return representation
• PUT → udpate, or create, or error
• DELETE → delete instance

Web API (REST style) 2/2

what about

• format
• HTTP status code
• pagination
• document centric
• ...

More important: what about data mashups and interoperability?

We need Standards!

RDF Model

Serialization format

• RDF/XML
• Turtle
• N3
• JSON-LD

Turtle

@prefix : <http://xmlns.com/foaf/0.1/> .

<mailto:person@example.net>
   :name "Anne Example-Person" ;
   :interest <http://www.foaf-project.org/> ,
        <http://www.ilrt.bris.ac.uk/discovery/2004/01/turtle/> .

JSON-LD

{
  "@context": {
    "name": "http://xmlns.com/foaf/0.1/name",
    "homepage": {
      "@id": "http://xmlns.com/foaf/0.1/homepage",
      "@type": "@id"
    }
  },
  "name": "Manu Sporny",
  "homepage": "http://manu.sporny.org/"
}

JSON-LD with @context in HTTP header

GET /ordinary-json-document.json HTTP/1.1
Host: example.com
Accept: application/json,*/*;q=0.1

====================================

HTTP/1.0 200 OK
...
Content-Type: application/json
Link: <http://json-ld.org/contexts/person>; rel="describedby"; type="application/ld+json"

{
  "name": "Markus Lanthaler",
  "homepage": "http://www.markus-lanthaler.com/",
  "depiction": "http://twitter.com/account/profile_image/markuslanthaler"
}

Vocabulary and ontologies

Querying RDF data with SPARQL

without any prior knowledge about the data!

What's in a URI?

aka. HttpRange-14

The fragment identifier component of a URI allows indirect identification of a secondary resource by reference to a primary resource

Linked Data apps

• dbpedia.org
• Freebase
• Wikidata
• Tabulator
• Drupal 7

Read-Write Linked Data

• initiated by Tim Berners-Lee in his Design Issues series
• PUT/POST RDF payloads
• GET SPARQL queries
• POST SPARQL Update queries

Linked Data Platform

• W3C just released a charter for a LDP Working Group
• very ambitious scope
• strong push from industry

Linked Data Platform, some technical comments

• based on IBM Basic Profile Submission and two similar implementations
• goal: be very accessible
• HTTP PATCH for lighter RDF modification
• default serialization format
• collections
• pagination
• integrating with existing SPARQL endpoint

The Semantic Web stack

Identity on the Web: WebID

Authentication: WebID Protocol

Authorization: WebACLs

Linked Data and the Cloud

Linked Data Cloud

Linking Open Data cloud diagram, by Richard Cyganiak and Anja Jentzsch. http://lod-cloud.net/

Linked Data 5 stars

Why it really matters

• Linked Open Data (especially eGov)
• Linked Enterprise Data
• Social Web

Take control over you data

We could use social networks as the way to track trust and identify people

Tim Berners-Lee @ #www2012