Kellogg Associates

Default term URI using @vocab.

RDFa 1.1 allows URIs to be expressed using an NCName, called a term, by using the @vocab attribute, an author can define a URI to be used for a bare word to turn it into a URI. Take for example the following:

<div vocab="http://xmlns.com/foaf/0.1/">
   <p about="#me" typeof="Person" property="name">Gregg Kellogg</p>
</div>

willgenerate the following triples:

<#me> a foaf:Person;
  foaf:name "Gregg Kellogg" .

Profile documents for defining prefixes and terms

A Profile document allows the specification of a set of URI mappings and term mappings in a single document. These documents are RDF formatted, and may or may not be RDFa. The following shows an example Profile document:

@prefix rdfa: <http://www.w3.org/ns/rdfa#> .
[ rdfa:prefix "foaf"; rdfa:uri "http://xmlns.com/foaf/0.1/"] .
[ rdfa:prefix "dc"; rdfa:uri "http://purl.org/dc/terms/"] .
[ rda:term "name"; rdfa:uri "http://xmlns.com/foaf/0.1/name"] .
[ rda:term "created"; rdfa:uri "http://purl.org/dc/terms/created"] .

This bit profile results in namespace mappings and a bare terms. Multiple vocabularies may be used together to create a namespace composed of terms from several vocabularies, without needing to describe them explicitly. These may then be used in a document as follows:

<div profile="http://example.com/my_vocab">
  <p about="#me">
    <span property="name">Gregg Kellogg</span>
    is the author of
    <a rel="created"
        resource="http://github.com/gkellogg/rdf_context">
      RdfContext
    </a>
  </p>
</div>

Namespace definitions

RDFa 1.1 deprecates the use of @xmlns for defining namespace prefixes. The @prefix attribute defines one or more mappings between prefixes and URIs. For example:

<div prefix="foaf: http://xmlns.com/foaf/0.1/ dc: http://purl.org/dc/terms/">
  <p about="#me">
    <span property="foaf:name">Gregg Kellogg</span>
    is the author of
    <a rel="dc:created"
        resource="http://github.com/gkellogg/rdf_context">
      RdfContext
    </a>
  </p>
</div>

Defines and uses two different namespace mappings.

URIs Everywhere

In RDFa 1.0, certain attributes took a URI, others a CURIE, and still others either a URI or a Safe CURIE. This is confusing, and RDFa 1.1 now allows either URIs, CURIEs, or SafeCURIEs to be used most anywhere (SafeCURIEs are maintained for backwards compatibility). For example:

<div>
    <p about="#me">
      <span property="http://xmlns.com/foaf/0.1/name">
        Gregg Kellogg
      </span>
      is the author of
      <a rel="http://purl.org/dc/terms/created"
          resource="http://github.com/gkellogg/rdf_context">
        RdfContext
      </a>
    </p>
  </div>
  

Change History

The following is the change log for this version of RdfContext. Note that one change may potentially break existing code: URIRef#namespace no longer throughs an exception if a mapping is not found. Other changes are noted here:

• RDFa 1.1 parsing supported (based on RDFa Core 1.1 W3C Working Draft 22 April 2010)
• Fix URIRef#short_name (and consequently #base and #namespace) to not extract a non-hierarchical path as a short_name
• Namespace no longer uses URIRef, but just acts on strings.
• Namespace#new does not take an optional _fragment_ argument any longer.
• Added Namespace#to_s to output "prefix: uri" format
• Graph#qname first trys generating using bound namespaces, then adds well-known namespaces.
• URIRef#to_qname and #to_namespace No longer generates an exception. Each take either a Hash or an Array of namespaces and tries them from longest to shortest.
• Improved Turtle and XML serializers in use of namespaces.
• Generate pending messages if RDFa tests skipped due to lack of Redland installation.
• Change dcterms: prefix to dc: (fully compatible with previous /elements/ definitions)