RDF and RDFa – A Backgrounder
A quick backgrounder on RDF, RDFa and RDFa Lite will probably be helpful before diving into the latest recommendations from W3C. RDF is a machine-readable language that can be expressed in HTML, text, JSON, and XML. It provides a model for data and syntax so that independent parties can easily use and exchange data. Sites using RDF can provide additional contextual details and establish relationships between content.
RDFa is a set of markup attributes meant in particular to augment visual data with machine-readable hints. In layman's terms, RDFa was created to help machines understand what humans intuitively get while browsing around the web. RDFa Lite is a minimal subset of RDFa consisting of a few attributes that meet most day-to-day needs of developers.
What’s New With RDFa
So what’s new with RDFa and RDFa Lite? The W3C is attempting to further specify how RDFa should be used in a variety of XML and HTML-based Web markup languages, and also offer a version of RDFa Lite suitable for novice developers. Let’s briefly review the highlights of each new W3C recommendation.
- RDFa Core 1.1 -- RDFa Core is a specification for attributes to express structured data in any markup language. The new recommendation is designed to ease specific rules about XHTML and also to expand the interoperability of RDFa with different language environments and make semantic data extractable from documents by conforming processors.
- RDFa Lite 1.1 -- The new version of RDFa Lite is designed to work for 80% of authors using simple data markup. RDFa Lite consists of five simple attributes; vocab, typeof, property, resource, and prefix. RDFa 1.1 Lite is completely upwards compatible with the full set of RDFa 1.1 attributes, meaning a user can add RDFa attributes to RDFa Lite if necessary.
- XTML + RDFa 1.1 -- This specification extends the XHTML 1.1 markup language with the attributes defined in RDFa Core 1.1.
- RDFa Primer -- The RDF Web Applications Working Group is now making a primer on adding structured data to HTML pages directly via RDFa available online. The document is considered a work in progress and not officially endorsed by W3C membership.
As the continuing expansion of Big Data brings more and more structured data (such as online transactional data) into the information stream of most organizations, a convenient way to integrate that data into an HTML format becomes more important.