HOME
The Info List - RDFa


--- Advertisement ---



RDFa
RDFa
(or Resource Description Framework
Resource Description Framework
in Attributes[1]) is a W3C Recommendation that adds a set of attribute-level extensions to HTML, X HTML
HTML
and various XML-based document types for embedding rich metadata within Web documents. The RDF data-model mapping enables its use for embedding RDF subject-predicate-object expressions within XHTML documents. It also enables the extraction of RDF model triples by compliant user agents. The RDFa
RDFa
community runs a wiki website to host tools, examples, and tutorials.[2]

Contents

1 History 2 Versions and variants

2.1 HTML+RDFa 2.2 RDFa
RDFa
1.0 2.3 RDFa
RDFa
1.1 2.4 RDFa
RDFa
Lite

3 Essence 4 Benefits 5 Usage

5.1 HTML+ RDFa
RDFa
statistics 5.2 RDFa
RDFa
editors 5.3 Examples

5.3.1 X HTML
HTML
+ RDFa
RDFa
1.0 5.3.2 HTML5
HTML5
+ RDFa
RDFa
1.1

6 See also 7 References 8 External links

History[edit] RDFa
RDFa
was first proposed by Mark Birbeck in the form of a W3C
W3C
note entitled X HTML
HTML
and RDF,[3] which was then presented to the Semantic Web Interest Group[4] at the W3C's 2004 Technical Plenary.[5] Later that year the work became part of the sixth public Working Draft of X HTML
HTML
2.0.[6][7] Although it is generally assumed that RDFa
RDFa
was originally intended only for X HTML
HTML
2, in fact the purpose of RDFa
RDFa
was always to provide a way to add a metadata to any XML-based language. Indeed, one of the earliest documents bearing the RDF/A Syntax name has the sub-title A collection of attributes for layering RDF on XML languages.[8] The document was written by Mark Birbeck and Steven Pemberton, and was made available for discussion on October 11, 2004. In April 2007 the X HTML
HTML
2 Working Group produced a module to support RDF annotation within the X HTML
HTML
1 family.[9] As an example, it included an extended version of X HTML
HTML
1.1 dubbed XHTML+RDFa 1.0. Although described as not representing an intended direction in terms of a formal markup language from the W3C, limited use of the XHTML+RDFa 1.0 DTD did subsequently appear on the public Web.[10] October 2007 saw the first public Working Draft of a document entitled RDFa
RDFa
in XHTML: Syntax and Processing.[11] This superseded and expanded upon the April draft; it contained rules for creating an RDFa
RDFa
parser, as well as guidelines for organizations wishing to make practical use of the technology. In October 2008 RDFa
RDFa
1.0 reached recommendation status.[12] RDFa
RDFa
1.1 reached recommendation status in June 2012.[13] It differs from RDFa
RDFa
1.0 in that it no longer relies on the XML-specific namespace mechanism. Therefore, it is possible to use RDFa
RDFa
1.1 with non- XML
XML
document types such as HTML
HTML
4 or HTML
HTML
5. Details can be found in an appendix to HTML
HTML
5.[14] An additional RDFa
RDFa
1.1 Primer document was last updated 17 March 2015.[1] (The first public Working Draft dates back to 10 March 2006.[15]) Versions and variants[edit] There are some main well-defined variants of the basic concepts, that are used as reference and as abbreviation to the W3C
W3C
standards. HTML+RDFa[edit] RDFa
RDFa
was defined in 2008 with the " RDFa
RDFa
in XHTML: Syntax and Processing" Recommendation.[16] Its first application was to be a module of XHTML. The HTML
HTML
applications remained, "a collection of attributes and processing rules for extending X HTML
HTML
to support RDF" expanded to HTML5, are now expressed in a specialized standard, the "HTML+RDFa" (the last is "HTML+ RDFa
RDFa
1.1 - Support for RDFa
RDFa
in HTML4 and HTML5"[17]). RDFa
RDFa
1.0[edit] The "HTML+RDFa" syntax of 2008 was also termed " RDFa
RDFa
1.0", so, there are no " RDFa
RDFa
Core 1.0" standard. In general this 2008's RDFa
RDFa
1.0 is used with the old X HTML
HTML
standards (as long as RDFa
RDFa
1.1 is used with X HTML5
HTML5
and HTML5). RDFa
RDFa
1.1[edit] Is the first generic (for HTML
HTML
and XML) RDFa
RDFa
standard, now (2015) the " RDFa
RDFa
Core 1.1" is in the Third Edition.[18] RDFa
RDFa
Lite[edit] Is a W3C
W3C
Recommendation (1.0 and 1.1) since 2009,[19] as "a minimal subset of RDFa, the Resource Description Framework
Resource Description Framework
in attributes, consisting of a few attributes that may be used to express machine-readable data in Web documents like HTML, SVG, and XML. While it is not a complete solution for advanced data markup tasks, it does work for most day-to-day needs and can be learned by most Web authors in a day".[20] In 2009 the W3C
W3C
was positioned[21] to retain RDFa
RDFa
Lite as unique and definitive standard alternative to Microdata.[22] The position was confirmed with the publication of the HTML5
HTML5
Recommendation in 2014. Essence[edit] The essence of RDFa
RDFa
is to provide a set of attributes that can be used to carry metadata in an XML
XML
language (hence the 'a' in RDFa). These attributes are:

about – a URI
URI
or CURIE specifying the resource the metadata is about rel and rev – specifying a relationship and reverse-relationship with another resource, respectively src, href and resource – specifying the partner resource property – specifying a property for the content of an element or the partner resource content – optional attribute that overrides the content of the element when using the property attribute datatype – optional attribute that specifies the datatype of text specified for use with the property attribute typeof – optional attribute that specifies the RDF type(s) of the subject or the partner resource (the resource that the metadata is about).

Benefits[edit] There are five "principles of interoperable metadata" met by RDFa.[23]

Publisher Independence – each site can use its own standards Data Reuse – data are not duplicated. Separate XML
XML
and HTML
HTML
sections are not required for the same content. Self Containment – the HTML
HTML
and the RDF are separated Schema Modularity – the attributes are reusable Evolvability – additional fields can be added and XML
XML
transforms can extract the semantics of the data from an X HTML
HTML
file

Additionally RDFa
RDFa
may benefit web accessibility as more information is available to assistive technology.[24] Usage[edit] There is a growing number of tools for better usage of RDFa vocabularies and RDFa
RDFa
annotation. HTML+ RDFa
RDFa
statistics[edit]

2013 survey pizza charts of percentual usage,[25] showing that 79% of URLs and 43% of domains use HTML+RDFa. The average 61% (the other 39% was Microformats) is the usage indicator.

The simplified approaches to semantically annotate information items in webpages were greatly encouraged by the HTML+ RDFa
RDFa
(released in 2008) and Microformats (since ~2005) standards. As of 2013[update] these standards were encoding events, contact information, products, and so on. Despite the vCard semantics (only basic items of person and organization annotations) dominance,[25] and some cloning of annotations along the same domain, the counting of webpages (URLs) and domains with annotations is an important statistical indicator for usage of semantically annotated information in the Web. The statistics of 2013 show that usage[25] of HTML+ RDFa
RDFa
has passed the usage of Microformats (illustration), consolidating a trend of growth shown in comparisons with 2011 and 2012. RDFa
RDFa
editors[edit]

Web-based RDFa
RDFa
editors There are already a few RDFa
RDFa
editors available online. RDFaCE (RDFa Content Editor) is a WYSIWYM
WYSIWYM
editor based on TinyMCE
TinyMCE
to support RDFa content authoring. It supports manual and semi-automatic generation of RDFa
RDFa
with the support of annotation services such as DBpedia Spotlight, OpenCalais, Alchemy API, among others.[26] RDFaCE-Lite is a version of RDFaCE also supporting Microdata and available as a WordPress plugin.[27]

Desktop RDFa
RDFa
editors AutôMeta is an environment for semi-automatic (or automatic) annotation of documents for publishing on the Web using RDFa. It also includes a RDFa
RDFa
extraction tool to provide the user with a view of the annotated triples. It is available in both CLI and GUI
GUI
interfaces.[28]

Examples[edit] The following is an example of adding Dublin Core metadata to an XML element in an X HTML
HTML
file. Dublin Core data elements are data typically added to a book or article (title, author, subject etc.)

<div xmlns:dc="http://purl.org/dc/elements/1.1/" about="http://www.example.com/books/wikinomics"> <span property="dc:title">Wikinomics</span> <span property="dc:creator">Don Tapscott</span> <span property="dc:date">2006-10-01</span> </div>

Moreover, RDFa
RDFa
allows the passages and words within a text to be associated with semantic markup:

<div xmlns:dc="http://purl.org/dc/elements/1.1/" about="http://www.example.com/books/wikinomics"> In his latest book <span property="dc:title">Wikinomics</span>, <span property="dc:creator">Don Tapscott</span> explains deep changes in technology, demographics and business. The book is due to be published in <span property="dc:date" content="2006-10-01">October 2006</span>. </div>

X HTML
HTML
+ RDFa
RDFa
1.0[edit] The following is an example of a complete XHTML+RDFa 1.0 document. It uses Dublin Core and FOAF, an ontology for describing people and their relationships with other people and things:

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML+RDFa 1.0//EN" "http://www.w3.org/MarkUp/DTD/xhtml-rdfa-1.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:foaf="http://xmlns.com/foaf/0.1/" xmlns:dc="http://purl.org/dc/elements/1.1/" version=" XHTML+RDFa 1.0" xml:lang="en"> <head> <title>John's Home Page</title> <base href="http://example.org/john-d/" /> <meta property="dc:creator" content="Jonathan Doe" /> <link rel="foaf:primaryTopic" href="http://example.org/john-d/#me" /> </head> <body about="http://example.org/john-d/#me"> <h1>John's Home Page</h1> <p>My name is <span property="foaf:nick">John D</span> and I like <a href="http://www.neubauten.org/" rel="foaf:interest" xml:lang="de">Einstürzende Neubauten</a>. </p> <p> My <span rel="foaf:interest" resource="urn:ISBN:0752820907">favorite book is the inspiring <span about="urn:ISBN:0752820907"><cite property="dc:title">Weaving the Web</cite> by <span property="dc:creator">Tim Berners-Lee</span></span></span>. </p> </body> </html>

In the example above, the document URI
URI
can be seen as representing an HTML
HTML
document, but the document URI
URI
plus the "#me" string http://example.org/john-d/#me represents the actual person, as distinct from a document about them. The foaf:primaryTopic in the header tells us a URI
URI
of the person the document is about. The foaf:nick property (in the first span element) contains a nickname for this person, and the dc:creator property (in the meta element) tells us who created the document. The hyperlink to the Einstürzende Neubauten website contains rel="foaf:interest", suggesting that John Doe is interested in this band. The URI
URI
of their website is a resource. The foaf:interest inside the second p element is referring to a book by ISBN number. The resource attribute defines a resource in a similar way to the href attribute, but without defining a hyperlink. Further into the paragraph, a span element containing an about attribute defines the book as another resource to specify metadata about. The book title and author are defined within the contents of this tag using the dc:title and dc:creator properties. Here are the same triples when the above document is automatically converted to RDF/XML:

<?xml version="1.0" encoding="UTF-8"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:foaf="http://xmlns.com/foaf/0.1/" xmlns:dc="http://purl.org/dc/elements/1.1/"> <rdf:Description rdf:about="http://example.org/john-d/"> <dc:creator xml:lang="en">Jonathan Doe</dc:creator> <foaf:primaryTopic> <rdf:Description rdf:about="http://example.org/john-d/#me"> <foaf:nick xml:lang="en">John D</foaf:nick> <foaf:interest rdf:resource="http://www.neubauten.org/"/> <foaf:interest> <rdf:Description rdf:about="urn:ISBN:0752820907"> <dc:creator xml:lang="en">Tim Berners-Lee</dc:creator> <dc:title xml:lang="en">Weaving the Web</dc:title> </rdf:Description> </foaf:interest> </rdf:Description> </foaf:primaryTopic> </rdf:Description> </rdf:RDF>

HTML5
HTML5
+ RDFa
RDFa
1.1[edit] The above example can be expressed without XML namespaces in HTML5:

<html prefix="dc: http://purl.org/dc/elements/1.1/" lang="en"> <head> <title>John's Home Page</title> <link rel="profile" href="http://www.w3.org/1999/xhtml/vocab" /> <base href="http://example.org/john-d/" /> <meta property="dc:creator" content="Jonathan Doe" /> <link rel="foaf:primaryTopic" href="http://example.org/john-d/#me" /> </head> <body about="http://example.org/john-d/#me"> <h1>John's Home Page</h1> <p>My name is <span property="foaf:nick">John D</span> and I like <a href="http://www.neubauten.org/" rel="foaf:interest" lang="de">Einstürzende Neubauten</a>. </p> <p> My <span rel="foaf:interest" resource="urn:ISBN:0752820907">favorite book is the inspiring <span about="urn:ISBN:0752820907"><cite property="dc:title">Weaving the Web</cite> by <span property="dc:creator">Tim Berners-Lee</span></span></span>. </p> </body> </html>

Note how the prefix foaf is still used without declaration. RDFa
RDFa
1.1 automatically includes prefixes for popular vocabularies such as FOAF.[29]

The minimal [30] document is:

<html lang="en"> <head> <title>Example Document</title> </head> <body vocab="http://schema.org/"> <p typeof="Blog"> Welcome to my <a property="url" href="http://example.org/">blog</a>. </p> </body> </html>

That is, it is recommended that all of these attributes are used: vocab, typeof, property; not only one of them. See also[edit]

Microformats, a simplified approach to semantically annotate data in web pages Open Graph protocol, a way to use RDFa
RDFa
to integrate web pages into the Facebook social graph Microdata - another approach at embedding semantics in HTML
HTML
using additional attributes eRDF, an alternative to RDFa
RDFa
(now obsolete) GRDDL, a way to extract (annotated) data out of X HTML
HTML
and XML documents and transform it into an RDF graph Schema.org, search-engine supported schemas for structured data markup on web pages that can be expressed as RDFa

References[edit]

^ a b " RDFa
RDFa
1.1 Primer" (3rd ed.). W3C. 17 March 2015. Retrieved 2016-09-02.  ^ " RDFa
RDFa
/ Tools".  ^ "X HTML
HTML
and RDF W3C
W3C
Note 14 February 2004". World Wide Web Consortium. 2004-02-14. Retrieved 2007-12-27.  ^ " W3C
W3C
Semantic Web Interest Group (SWIG)".  ^ " Semantic Web Interest Group". XML.com. 2004-03-03. Retrieved 2007-12-27.  External link in publisher= (help) ^ "X HTML
HTML
2.0 W3C
W3C
Working Draft 22 July 2004, 19. X HTML
HTML
Metainformation Attributes Module". World Wide Web
World Wide Web
Consortium. 2004-07-22. Retrieved 2007-10-06.  ^ " XML
XML
and Semantic Web W3C
W3C
Standards Timeline" (PDF).  ^ "RDF/A Syntax: A collection of attributes for layering RDF on XML languages". 2004-10-11. Retrieved 2009-05-14.  ^ "X HTML
HTML
RDFa
RDFa
Modules, Modules to support RDF annotation of elements, W3C
W3C
Editor's Draft 2 April 2007". World Wide Web
World Wide Web
Consortium. 2007-04-02. Retrieved 2007-10-06.  ^ For examples of this, see: "Archived copy". Archived from the original on 2007-10-11. Retrieved 2007-10-06.  "Archived copy". Archived from the original on 2007-12-14. Retrieved 2007-10-06.  ^ " RDFa
RDFa
in XHTML: Syntax and Processing, A collection of attributes and processing rules for extending X HTML
HTML
to support RDF, W3C
W3C
Working Draft 18 October 2007". World Wide Web
World Wide Web
Consortium. 2007-10-18. Retrieved 2007-10-20.  ^ " RDFa
RDFa
in XHTML: Syntax and Processing, A collection of attributes and processing rules for extending X HTML
HTML
to support RDF, W3C Recommendation 14 October 2008". World Wide Web
World Wide Web
Consortium. 2008-10-14. Retrieved 2008-10-15.  ^ " RDFa
RDFa
Core 1.1 - Syntax and processing rules for embedding RDF through attributes". World Wide Web
World Wide Web
Consortium. 2012-06-07. Retrieved 2012-08-25.  ^ "HTML+ RDFa
RDFa
1.1 - Support for RDFa
RDFa
in HTML4 and HTML5". World Wide Web Consortium. 2012-03-29. Retrieved 2012-08-25.  ^ "RDF/A Primer 1.0". W3C. 10 March 2006. Retrieved 2016-09-02.  ^ " RDFa
RDFa
in XHTML: Syntax and Processing - A collection of attributes and processing rules for extending X HTML
HTML
to support RDF", W3C Recommendation 14 October 2008. http://www.w3.org/TR/2008/REC-rdfa-syntax-20081014/ ^ "HTML+ RDFa
RDFa
1.1 - Support for RDFa
RDFa
in HTML4 and HTML5", W3C Recommendation 22 August 2013. http://www.w3.org/TR/html-rdfa/ ^ " RDFa
RDFa
Core 1.1 - Third Edition - Syntax and processing rules for embedding RDF through attribute", W3C
W3C
Recommendation 17 March 2015. https://www.w3.org/TR/2015/REC-rdfa-core-20150317/ ^ first draft 1.1 cite ~2009 as ~year of " RDFa
RDFa
Lite 1.0"... Please check better reference. ^ " RDFa
RDFa
Lite 1.1", W3C
W3C
Recommendation 07 June 2012. http://www.w3.org/TR/rdfa-lite/ (second edition at 2015) ^ Final W3C
W3C
position (ISSUE-76), establishing that Microdata syntax simply duplicates what RDFa
RDFa
Lite already does. ^ "Mythical Differences: RDFa
RDFa
Lite vs. Microdata - The Beautiful, Tormented Machine".  ^ Building Interoperable Web Metadata ^ " RDFa
RDFa
– Implications for Accessibility – Standards Schmandards".  ^ a b c "Web Data Commons – RDFa, Microdata, and Microformat Data Sets". section 3.1, "Extraction Results from the November 2013 Common Crawl Corpus". 2013. Retrieved 2015-02-21.  ^ "RDFaCE — Agile Knowledge Engineering and Semantic Web (AKSW)".  ^ "RDFaCE — Agile Knowledge Engineering and Semantic Web (AKSW)".  ^ "Google Code Archive - Long-term storage for Google Code Project Hosting".  ^ " RDFa
RDFa
Core Initial Context - Vocabulary Prefixes". World Wide Web Consortium. 2012-05-27. Retrieved 2012-08-25.  ^ "Example of an HTML+ RDFa
RDFa
1.1 document" at http://www.w3.org/TR/html-rdfa/#document-conformance

External links[edit]

RDFa
RDFa
Primer hGRDDL RDFa
RDFa
– Implications for Accessibility Mark Birbeck presenting RDFa
RDFa
at Google in May 2008

v t e

Semantic Web

Background

Databases Hypertext Internet Ontologies Semantic networks World Wide Web

Sub-topics

Data Web Dataspaces Hyperdata Linked data Rule-based systems

Applications

Semantic analytics Semantic broker Semantic computing Semantic mapper Semantic matching Semantic publishing Semantic reasoner Semantic search Semantic service-oriented architecture Semantic wiki

Related topics

Collective intelligence Description logic Folksonomy Geotagging Information architecture Knowledge extraction Knowledge management Knowledge representation and reasoning Library 2.0 Metadata Mind mapping ODBC References Topic map Web 2.0 Web engineering Web Science Trust

Standards

Syntax and supporting technologies

HTTP IRI

URI

RDF

triples RDF/XML JSON-LD Turtle TriG Notation3 N-Triples TriX (no W3C
W3C
standard)

RRID SPARQL XML

Schemas, ontologies and rules

Common Logic OWL RDFS Rule Interchange Format Semantic Web Rule Language ALPS

Semantic annotation

eRDF GRDDL Microdata Microformats RDFa SAWSDL Facebook Platform

Common vocabularies

DOAP Dublin Core FOAF Schema.org SIOC SKOS

Microformat vocabularies

hAtom hCalendar hCard hProduct hReci

.