An Introduction to RDFa QingXia Liu

Contents What is RDFa? Why RDFa? Versions of RDFa An Example

What is RDFa? Resource Description Framework in attributes – First proposed by Mark Birbeck in 2004Mark Birbeck – A W3C Recommendation

What is RDFa? The gap between what programs and humans understand: What browsers seewhat humans see

What is RDFa? Aim: to allow a single RDF graph to be carried in various types of document markup

What is RDFa? Essence: attributes machine- readable it provides a set of markup attributes to augment the visual information on the Web with machine- readable hints. These attributes are: about, src, rel, rev, href, resource, property, content, datatype, typeof…

What is RDFa? HTML : HTML :... The trouble with Bob Date: Alice Jo's Barbecue Date: Eve HTML + RDFa 1.1:... The trouble with Bob Date: Alice Jo's Barbecue Date: Eve mark up human-readable data with machine-readable indicators

What is RDFa? Example: The trouble with Bob Date: Alice Jo's Barbecue Date: Eve

Why RDFa? Embedding RDF subject-predicate-object expressions in existing markup languages such as XHTML.RDFsubject-predicate-object expressions Enables the extraction of RDF model triples by compliant user agents Apps: – To provide richer search results by extracting fine-grained structured details from the Web pages they crawl

Versions RDFa 1.0 – was specified only for XHTML RDFa 1.1 – is the newer version specified for both XHTML and HTML5. – also works for any XML-based languages like SVG

Changes Differences between RDFa 1.1 and RDFa1.0: – The removal of the specific rules for XHTML - these are now defined in XHTML + RDFa – Dayatype Expansion : RDFa attributes can contain Terms, CURIES, or Absolute IRIs. – Host languages are permitted to define collections of default terms, default prefix mappings, and a default vocabulary – The ability to define a default vocabulary to use for Terms that are undefined (via – Terms are required to be compared in a case-insensitive manner. – A richer behavior of attribute, that can replace, in many cases attribute. – A slightly different handling making it better adapted to practical usage

Current Status Standards: – RDFa Core 1.1 – XHTML+RDFa 1.1 – RDFa Lite 1.1 Group Notes: before RDFa API, RDF Interfaces, RDFa 1.1 Primer, HTML Data Guide, XML in HTML Meeting Report Drafts: HTML+RDFa

Example The trouble with Bob... Alice Birpemswick, Phone:

Example The trouble with Bob... Alice Birpemswick, Phone:

Example

Example The trouble with Bob Alice The trouble with Bob Alice Alice Birpemswick, Phone: Alice Birpemswick, Phone:

Example

References The W3C RDFa 1.1 Primer The W3C RDFa 1.1 Core The Wikipedia entry on RDFa

Thank you !