RDFa

RDFa is a syntax which makes it possible to describe data structured in a Web page. Thus formally described, the data can then be the subject of complex automated treatments, via adapted tools. The RDFa code is invisible for the Net surfer and does not affect the contents of the page.

RDFa is a standard under development with W3C.

Principle

RDFa is a whole of elements and attributes. This syntax is in conformity with the model RDF: data described in RDFa can thus be easily transformed into data RDF. For this reason, RDFa is a technique making it possible to implement the semantic Web.

RDFa uses to some extent existing syntax HTML:

the attribute class - allowing to specify the type of the object
the attribute id - indirectly, being used to define the URI of an object in the page
the attributes rel , rev and href - specifying a relationship to another resource

RDFa adds its own elements, the attributes:

butt - a URI specifying the resource described by the metadata; in its absence, it is about the document in progress
property - specifying a property for the contents of a content element
- optional attribute which replaces the contents of an element when one uses the attribute of property
datatype - optional attribute which specifies the type of data of the contents.

Comparison with the microformats

RDFa is a technique close to the Microformats in what it makes it possible to add of semantics the contents of a page. They differ however on two principal aspects:

RDFa is extensible very easily owing to the fact that it uses spaces of name
RDFa is normally usable only with XHTML 1.1 and higher; the microformats, on the other hand, adapt to the 2 most widespread standards on the Web, HTML 4.01 and XHTML 1.0.

Example of RDFa code

The following example shows the addition of metadata of the Dublin Core in a page HTML. The properties of Dublin core are used to describe a book or an article (title, author, subject, etc)

Wikinomics Don Tapscott 2006-10-01

RDFa can also fit naturally in the flood of the contents:

In its last book Wikinomics, Don Tapscott explain the deep technological changes, demographic and economic. This book was published in October 2006 .

Examples of uses

Using an extension of the Firefox navigator, it is possible, according to the RDFa data:

to locate automatically geographically an individual (using a service like Google Maps)
to visualize the file FOAF of a person (detailed description in RDF) using the Foaf service To explore

Another type of example, the seizure of RDFa metadata in management tools of contents, can make it possible this last automatically to post the wikipédia definitions concepts thus described.

See too

Resource Description Framework
Microformats

Refer

RDFa To precede * RDFa Uses Boxes: Scenarios for Embedding RDF in HTML * RDFa Syntax * FAQ RDFa * Let us have fun with RDFa, by Gautier Poupeau.
Let us amuse with RDFa… and Operator, by Charles Nepote.
rdfa.info, blog specialized.
off has Comparison Microformats, eRDF, and RDFa.

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