RDFa 1.1: Adding Machine-readable Hints to your Webpage

RDFa 1.1

Adding Machine-readable Hints
to your Webpage

Neue Fähigkeiten zum einfachen Editieren
und Konsumieren von
RDFa Auszeichnungen

Benjamin Adrian W3C Tag, 15.09.2010, Berlin
http://www.dfki.de/~adrian

What is RDFa about?
Goal: Add machine-readable hints to web pages RDF(a)

Generate RDF triples from a web page ...
your personal vision attributes
awesome !!!

your machine's vision
<http://my.safaribooksonline.com/0975841947> a gr:Offering ;
rdfs:label "Safari Books Online" ;
gr:includesObject
[ a gr:TypeAndQuantityNode ;
gr:amountOfThisGood "1"^^xsd:float ;
gr:typeOfGood <urn:x-domain:oreilly.com:product:9780975841945.SAF>
].

...

… and start scripting!

W3C Tag, 15.09.2010, Berlin

The RDFa Working Group Member
Bouba Fanta

Ben Adida

Jeffrey Sonstein Markus Gylling

Shane McCarron Abhijit Gaikwad
Manu Sporny Steven Pamperton
Robert Weir

Toby Inkster
Jean-Pierre
Evain Benjamin Adrian
Ivan Herman
Knud Möller Nan Ma Sarah Pulis
John O'Donovan Mark Birbeck

last update, 2010-09-13

What is new in RDFa 1.1
Goal: Make RDFa easier:
● for authors to write and to copy/paste content
● for developers to script

Current Contributions:
● Introduced prefix, profile, vocab instead of overloading xmlns
● Draft an RDFa API
● Let RDFa processors separate between a default RDF graph and a
processor RDF graph containing error triples
● Use plain URIs in every RDFa attribute


Writing RDFa 1.1


How do I tell my computer what this means?


Your computer understands RDF

Neue Fähigkeiten zum einfachen Editieren und 11:30
Konsumieren von RDFa Auszeichnungen

12:15

Benjamin Adrian

DFKI

Speak to your computer in RDF concepts

Neue Fähigkeiten zum einfachen Editieren und 2010-09-15T11:30:00
Konsumieren von RDFa Auszeichnungen
vcal:dtstart
#rdfa_talk
dc:title
vcal:dtend
vcal:organizer
2010-09-15T12:15:00

#ben
foaf:workplaceHomepage
foaf:name foaf:member
http://www.dfki.de
Benjamin Adrian #dfki foaf:homepage

foaf:name

DFKI

Same RDF in TURTLE Syntax
@prefix foaf: <http://xmlns.com/foaf/0.1/>
@prefix vcard: <http://www.w3.org/2002/12/cal#>
@prefix dc: <http://purl.org/dc/terms/>

<#ben>
foaf:name „Benjamin Adrian“;
foaf:workplaceHomepage <http://www.dfki.de>;
foaf:member <#dfki>;
vcard:organizer <#rdfa_talk>.
<#dfki>
foaf:name „DFKI“;
foaf:homepage <http://www.dfki.de>.
<#rdfa_talk>
vcard:dtstart „2010-09-15T11:30:00“^xsd:DateTime;
vcard:dtend „2010-09-15T12:15:00“^xsd:DateTime;
dc:title „Neue Fähigkeiten zum einfachen
Editieren und Konsumieren von RDFa
Auszeichnungen“.


Back to the HTML content
<tr>
<td>
<span>11:30</span> - <span>12:15</span>
</td>
<td>
<div>
Neue Fähigkeiten zum einfachen Editieren und Konsumieren
von RDFa Auszeichnungen
</div>
<a href="/referenten-2010/details/adrian.html">
Benjamin Adrian
</a>
,
<span>DFKI</span>
</td>
</tr>


CURIEs and prefixes … in RDFa
<tr prefix=“dc: http://purl.org/dc/terms/“>
<td>
<span>11:30</span> - <span>12:15</span> CURIE
</td>
<td>
<div property=“dc:title“>
Neue Fähigkeiten zum einfachen Editieren und Konsumieren
von RDFa Auszeichnungen
</div>
Benjamin Adrian
</a>
,
Use prefix for
<span>DFKI</span> resolving CURIEs.
</td> (xmlns is depricated)
</tr>


Default Vocabularies … in RDFa
<tr prefix=“dc: http://purl.org/dc/terms/“
vocab=“http://www.w3.org/2002/12/cal#“>
<td>
<span property=“dtstart“>11:30</span> -
<span property=“dtend“>12:15</span>
</td> short name
<td>
Neue Fähigkeiten zum einfachen Editieren und Konsumieren von
RDFa Auszeichnungen
</div>
Benjamin Adrian
</a>
,
<span>DFKI</span>
</td>
</tr>


Bundle vocabularies, prefixes … in RDFA
<div profile="http://www.heppnetz.de/grprofile/">
<span about="#company" typeof="gr:BusinessEntity“>
<span property="gr:legalName">
Hepp's bakery
</span>
, see also the
<a rel="rdfs:seeAlso" href="http://example.org/bakery">
home page of the bakery.
Use profile documents for defining
</a> a bundle of vocabularies or prefixes.
</div>
Profiles can be defined in RDFa,
RDFXML, or Turtle.


Refine content … in RDFa
<tr prefix=“dc: http://purl.org/dc/terms/“
vocab="http://www.w3.org/2002/12/cal#">
<td>
<span property=“dtstart“
content=“2010-09-15T11:30:00“>11:30</span> -
<span property=“dtend“
content=“2010-09-15T12:15:00“>12:15</span>
</td>
<td>
Neue Fähigkeiten zum einfachen Editieren und Konsumieren von
RDFa Auszeichnungen
</div>
Benjamin Adrian
</a>
,
<span>DFKI</span>
</td>
</tr>

Define multiple entities … in RDFa
<tr prefix=“dc: http://purl.org/dc/terms/“ about=“#talk“
vocab=“http://www.w3.org/2002/12/cal#“ typeof=“Vevent“>
<td>
content=“2010-09-15T11:30:00“>11:30</span> -
content=“2010-09-15T12:15:00“>12:15</span>
</td>
<td>
Neue Fähigkeiten zum einfachen Editieren und Konsumieren von RDFa
Auszeichnungen
</div>
<a about=“#ben“ property=“foaf:name“
href="/referenten-2010/details/adrian.html">
Benjamin Adrian
</a>
,
<span typeof=“foaf:Organization“
property=“foaf:name“>DFKI</span>
</td>
</tr>


Connect entities … in RDFa
<tr prefix=“dc: http://purl.org/dc/terms/“ about=“#talk“
vocab=“http://www.w3.org/2002/12/cal#“ typeof=“Vevent“>
<td>
content=“2010-09-15T11:30:00“>11:30</span> -
content=“2010-09-15T12:15:00“>12:15</span>
</td>
<td>
Neue Fähigkeiten zum einfachen Editieren und Konsumieren von RDFa
Auszeichnungen
</div>
<a about=“#ben“ property=“foaf:name“
rel=“organizer“ resource=“#talk“
href="/referenten-2010/details/adrian.html">
Benjamin Adrian
</a>
,
<span typeof=“foaf:Organization“ property=“foaf:name“
inv=“foaf:member“ resource=“#ben“>DFKI</span>
</td>
</tr>


Scripting with RDFa 1.1


3 steps to get your RDFa objects

1. Parsing DOM objects that contain embedded metadata

2. Extraction of the embedded metadata into a data store

3. Querying a data store in order to retrieve PropertyGroups


General Architecture

Document Model

Object-centric view of extracted data

Extract data, Provide views

Storage Level

Basic data structures


RDFa API

Retrieving PropertyGroups

Retrieves a list of PropertyGroups by their type.
document.getItemsByType(type)

Retrieves a single PropertyGroup by its subject.
document.getItemBySubject(type)

Retrieves a list of PropertyGroups by a particular property and optional value.
document.getItemsByProperty(property, optional value)


RDFa API

Retrieving DOM Elements

Retrieves a list of DOM Nodes by the type of data that they express.
document.getElementsByType(type)

Retrieves a list of DOM Nodes by the subject associated with the data that they
express.
document.getElementsBySubject(type)

Retrieves a list of DOM Nodes by a particular property and optional value that
each expresses.
document.getElementsByProperty(property, optional value)


RDFa API

Advanced Processing

Retrieves an array of PropertyGroups based on a set of selection criteria.
document.data.query.select(query, template)

Filters a given DataStore by matching a given triple pattern.
document.data.store.filter(pattern)

Iterates through a DOM, using a low-memory, stream-based approach,
matching on the given triple pattern.
document.data.parser.iterate(pattern)


RDFa API for beginners

var store = document.data.createStore();
document.data.createParser("rdfa", store).parse();
//document.data.createParser(“hCard“, store).parse();

document.data.context.setMapping(„foaf“,
„http://xmlns.com/foaf/0.1/“);

for(var person : document.getItemsByType(„foaf:Person“)) {

for(var element: document.getElementsBySubject(person.get(„uri“))) {
element.style.setProperty(“color“, “#00cc00“, null);
addPopupOnClickEvent(person.get(„uri“), element);
}

}


RDFa API for advanced beginners
...
var events = query.select( { „rdf:type“: „vcal:Event“ },
{ „rdf:type“ : „type“ , „dc:title“ : „title“,
„vcal:dtstart“: „start“, „vcal:dtend“: „end“ }
);

for(var i = 0; i < events.length; i++) {

var event = events[i];
anchor = document.createElement(„a“);
anchor.href = „http://www.google.com/calendar/event?“
+ “action=TEMPLATE“ + „&text=“ + event.summary + „&dates=“
+ event.start + „/“ + event.end;

button = document.createElement(„img“);
button.src = „http://www.google.com/calendar/images/ext/gc_button6.gif“;
anchor.appendChild(button);

event.info(„rdf:type“, „source“)[0].appendChild(anchor);
}


Useful Tools
● Use check.rdfa for checking if your RDFa content is
compliant with Google's Rich Snippet, or Facebook's Open
Graph Protocol (http://check.rdfa.info/)

● Use the CMS system Drupal for adding RDFa data to your
web pages.

● Use the RDFa distiller for extracting RDF triples from
RDFa content (http://www.w3.org/2007/08/pyRdfa/)


Outlook
What's next in RDFa 1.1?

Improve support of RDFa in HTML lists
Self contained error handling
Publish a good RDFa Primer.
Eat your own dog food, means to really implement the RDFa API.

...


Thanks for your interest!

Have fun with RDFa

Benjamin Adrian
http://www.dfki.de/~adrian

RDFa 1.1: Adding Machine-readable Hints to your Webpage

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