RDFa API

Methods

registerTypeConversion

Registers a type converter from given IRI datatype to a native language dataype in the current programming language.

Parameter	Type	Nullable	Optional	Description
iri	DOMString	✘	✘	A string specifying the IRI datatype. The string may be a CURIE. For example: http://www.w3.org/2001/XMLSchema-datatypes#integer or xsd:integer.
converter	TypedLiteralConverter	✘	✘	A function that converts the TypedLiteral's value into a native language datatype in the current programming language.

No exceptions.

Return type: void

setMapping

Registers a mapping from a prefix to an IRI . The given IRI must be a full IRI. For example, if a developer wants to specify the foaf IRI mapping, they would call setMapping("foaf", "http://xmlns.com/foaf/0.1/"). Calling the setMapping() method with a prefix value that does not exist results in the creation of a new mapping. Calling the method with a null IRI value will remove the mapping.

Parameter	Type	Nullable	Optional	Description
prefix	DOMString	✘	✘	The prefix to put into the mapping as the key. (e.g., foaf)
iri	DOMString	✘	✘	The IRI reference to place into the mapping as the mapped value of the given prefix. (e.g., "http://xmlns.com/foaf/0.1/")

No exceptions.

Return type: void

Attributes

size of type unsigned long, readonly

A non-negative integer that specifies the size, in RDFTriples, of the store.

No exceptions.

Methods

add

Adds an RDFTriple to the Data Store. Returns True if the RDFTriple was added to the store successfully.

Parameter	Type	Nullable	Optional	Description
triple	RDFTriple	✘	✘	The triple to add to the Data Store.

No exceptions.

Return type: boolean

clear

Clears all data from the store.

No parameters.

No exceptions.

Return type: void

createBlankNode

Creates a Blank Node given an optional name value.

Parameter	Type	Nullable	Optional	Description
name	DOMString	✘	✔	The name of the Blank Node, which will be used when Stringifying the Blank Node.

No exceptions.

Return type: BlankNode

createIRI

Creates an IRI given a value and an optional Node.

Parameter	Type	Nullable	Optional	Description
iri	DOMString	✘	✘	The IRI reference's lexical value.
node	Node	✘	✔	An optional DOM Node to associate with the IRI.

No exceptions.

Return type: IRI

createPlainLiteral

Creates a Plain Literal given a value, an optional language and an optional DOM origin Node.

Parameter	Type	Nullable	Optional	Description
value	DOMString	✘	✘	The value of the IRI. The value can be either a full IRI or a CURIE.
language	DOMString	✔	✔	The language that is associated with the Plain Literal encoded according to the rules outlined in [BCP47].
origin	Node	✘	✔	The DOM Node that should be associated with the Plain Literal

No exceptions.

Return type: PlainLiteral

createTriple

Creates an RDF Triple given a subject, predicate and object. If any incoming value does not match the requirements listed below, a Null value must be returned by this method.

Parameter	Type	Nullable	Optional	Description
subject	Object	✘	✘	The subject value of the RDF Triple. The value must be either an IRI or a BlankNode.
predicate	Object	✘	✘	The predicate value of the RDF Triple.
object	Object	✘	✘	The object value of the RDF Triple. The value must be an IRI, PlainLiteral, TypedLiteral, or BlankNode.

No exceptions.

Return type: RDFTriple

createTypedLiteral

Creates a Typed Literal given a value, a type and an optional associated DOM Node.

Parameter	Type	Nullable	Optional	Description
value	DOMString	✘	✘	The value of the Typed Literal.
type	DOMString	✘	✘	The IRI type of the Typed Literal. The argument can either be a full IRI or a CURIE.
origin	Node	✘	✔	The DOM Node to associate with the Typed Literal.

No exceptions.

Return type: TypedLiteral

filter

Returns an DataStore, which consists of zero or more RDFTriple objects.

Parameter	Type	Nullable	Optional	Description
subject	Object	✔	✘	The subject filter pattern which is used to filter RDFTriple objects. Values can be of type IRI, BlankNode, or Null. If the subject is a non-Null value, the RDFTriple must not be placed in the final output Array unless the given subject matches the RDFTriple's subject. If subject is set to Null, the filter must not reject any triple based on the subject.
predicate	IRI	✔	✔	The predicate filter pattern which is used to filter RDFTriple objects. Values can be of type IRI or Null. If the predicate is a non-Null value, the RDFTriple must not be placed in the final output Array unless the given predicate matches the RDFTriple's predicate. If predicate is set to Null, the filter must not reject any triple based on the predicate.
object	Object	✔	✔	The object filter pattern which is used to filter RDFTriple objects. Values can be of type IRI, TypedLiteral, PlainLiteral, BlankNode, or Null. If the object is a non-Null value, the RDFTriple must not be placed in the final output Array unless the given object matches the RDFTriple's object. If object is set to Null, the filter must not reject any triple based on object.
element	Node	✔	✔	The parent DOM Node where filtering should start. The implementation must only consider RDF triples on the current DOM Node and its children.
filter	RDFTripleFilter	✘	✔	A user defined function, returning a true or false value, that determines whether or not an RDFTriple should be added to the final Array.

No exceptions.

Return type: DataStore

forEach

Calls the given callback for each item in the Data Store.

Parameter	Type	Nullable	Optional	Description
callback	function	✘	✘	A function that takes the following arguments: index, subject, predicate, object. The function is called for each item in the Data Store.

No exceptions.

Return type: void

get

Returns the RDFTriple object at the given index in the list.

Parameter	Type	Nullable	Optional	Description
index	unsigned long	✘	✘	The index of the RDFTriple in the list to retrieve. The value must be a positive integer value greater than or equal to zero and less than DataStore::length.

No exceptions.

Return type: Object

Attributes

store of type DataStore

The DataStore that is associated with the DataParser. The results of each parsing run will be placed into the store.

No exceptions.

Methods

iterate

Returns an DataIterator, which is capable of iterating through a set of RDF triples, one RDFTriple at a time. The DataIterator is most useful in small memory footprint environments, or in documents that contain a very large number of triples.

Parameter	Type	Nullable	Optional	Description
subject	Object	✔	✘	The subject filter pattern which is used to filter RDFTriple objects. Values can be of type IRI, BlankNode, or Null. If the subject is a non-Null value, the RDFTriple must not be output via the DataIterator unless the given subject matches the RDFTriple's subject. An IRI value must be either a full IRI or a CURIE. If subject is set to Null, the filter must not reject any triple based on the subject.
predicate	DOMString	✔	✔	The predicate filter pattern which is used to filter RDFTriple objects. Values can be of type IRI or Null. If the predicate is a non-Null value, the RDFTriple must not be output via the DataIterator unless the given predicate matches the RDFTriple's predicate. An IRI value must be either a full IRI or a CURIE. If predicate is set to Null, the filter must not reject any triple based on the predicate.
object	Object	✔	✔	The object filter pattern which is used to filter RDFTriple objects. Values can be of type IRI, TypedLiteral, PlainLiteral, BlankNode, or Null. If the object is a non-Null value, the RDFTriple must not be output via the DataIterator unless the given object matches the RDFTriple's object. An IRI value must be either a full IRI or a CURIE. If object is set to Null, the filter must not reject any triple based on object.
element	Node	✔	✔	The parent DOM Node where filtering should start. The implementation must only consider RDF Triples on the current DOM Node and its children.
filter	RDFTripleFilter	✘	✔	A user defined function, returning a true or false value, that determines whether or not an RDFTriple should be output via the DataIterator.

No exceptions.

Return type: DataIterator

parse

Parses starting at the given DOM Element and populates the store with the information that is discovered. If a starting element isn't specified, or the value of the starting element is Null, then the document object must be used as the starting element.

Even though a specific DOM Element can be specified to start the process of placing RDFTriples into the DataStore, the entire document must be processed by an RDFa Processor due to context that may affect the generation of a set of triples. Specifying the DOM Element is useful when a subset of the document data is to be stored in the Data Store.

There are two ways to approach this mechanism. The first is to only parse the sub-tree, ignoring the context of the greater document. The second is to parse the entire document, but only store triples that are a part of the sub-tree.

Parameter	Type	Nullable	Optional	Description
domElement	Element	✘	✘	The DOM Element that should trigger triple generation.

No exceptions.

Return type: boolean

Attributes

filter of type RDFTripleFilter, readonly

The RDFTripleFilter is a function that is provided by developers to filter RDFTriples in a subtree.

No exceptions.

root of type Node, readonly

The DOM Node that was used as the starting point for extracting RDFTriples.

No exceptions.

store of type DataStore

The DataStore that is associated with the DataIterator.

No exceptions.

triplePattern of type RDFTriple, readonly

An RDF triple pattern is a set of filter parameters that can be passed to an RDFTripleFilter to match particular triple patterns.

No exceptions.

Methods

next

Returns the next RDFTriple object that is found in the DOM subtree or NULL if no more RDFTriples match the filtering criteria.

No parameters.

No exceptions.

Return type: RDFTriple

Attributes

origin of type Element

The DOM Element that specified the first type definition for this PropertyGroup.

No exceptions.

properties of type Sequence[IRI]

A list of all attributes that are available via this PropertyGroup.

No exceptions.

Methods

get

Returns a sequence of IRIs, BlankNodes, PlainLiterals, and/or TypedLiterals in the projection that have a predicate IRI that is equivalent to the given value.

Parameter	Type	Nullable	Optional	Description
predicate	DOMString	✘	✘	A stringified IRI representing a predicate whose values are to be retrieved from the PropertyGroup. For example, using a predicate of http://xmlns.com/foaf/0.1/name will return a sequence of values that represent FOAF names in the PropertyGroup. The given predicate may also be a CURIE.

No exceptions.

Return type: Sequence[any]

The Origin Pointer

document.getItemsByType() returns a list of Property Groups that match the query. By default there is always a property called origin on the Property Group and all of its properties, which refers back to an element in the source document.

The origin property allows programmers to manipulate DOM objects based on the embedded metadata that they refer to. For example, to set a thin blue border on each Person, we could do this:

var people = document.getItemsByType("foaf:Person");
 
for (var i = 0; i < people.length; i++) {
  people[i].origin.style.border = "1px solid blue";
}

Property Group Templates

A query can be used to retrieve not only basic Property Groups, but can also specify how Property Groups are built by utilizing Property Group Templates.

For example, assume our source document contains the following event, marked up using the Google Rich Snippet Event format (example taken from the Rich Snippet tutorial, and slightly modified):

<div vocab="http://rdf.data-vocabulary.org/#" typeof="Event">
  <a href="http://www.example.com/events/spinaltap" rel="v:url" 
     property="summary">Spinal Tap</a>
  <img src="spinal_tap.jpg" rel="v:photo" />
  <span property="description">After their highly-publicized search for a new drummer, 
  Spinal Tap kicks off their latest comeback tour with a San Francisco show. </span>
 
  When:
  <span property="startDate" content="20091015T1900Z">Oct 15, 7:00PM</span>—
  <span property="endDate" content="20091015T2100Z">9:00PM</span>
</div>

To query for all Event Property Groups we know that we can do this:

var ar = query.select({ "rdf:type": "http://rdf.data-vocabulary.org/#Event" });

However, to build a special PropertyGroup that contains the summary, start date and end date, we need only do this:

var events = query.select({ "rdf:type": "http://rdf.data-vocabulary.org/#Event" },
                          {"rdf:type" : "type", "v:summary": "summary", 
                           "v:startDate": "start", "v:endDate": "end"} );

The second parameter is a PropertyGroup Template. Each key-value pair specifies an IRI to map to an attribute in the resulting PropertyGroup object.

Exposing the embedded data in each Property Group makes it easy to create an HTML anchor that will allow users to add the event to their Google Calendar, as follows:

var anchor, button, i, pg;
 
for (i = 0; i < events.length; i++) {
  // Get the Property Group:
  pg = events[i];
 
  // Create the anchor
  anchor = document.createElement("a");
 
  // Point to Google Calendar
  anchor.href = "http://www.google.com/calendar/event?action=TEMPLATE"
    + "&text=" + pg.summary + "&dates=" + pg.start + "/" + pg.end;
 
  // Add the button
  button = document.createElement("img");
  button.src = "http://www.google.com/calendar/images/ext/gc_button6.gif";
  anchor.appendChild(button);
 
  // Add the link and button to the DOM object
  pg.origin.appendChild(anchor);
}

The result will be that the event has an HTML a element at the end (and any Event on the page will follow this pattern):

<div vocab="http://rdf.data-vocabulary.org/#" typeof="Event">
  .
  .
  .
  <a href="http://www.google.com/calendar/event?action=TEMPLATE&text=Spinal+Tap&dates=20091015T1900Z/20091015T2100Z">
    <img src="http://www.google.com/calendar/images/ext/gc_button6.gif" />
  </a>
</div>

For more detailed information about queries see the Data Query interface.

Attributes

store of type DataStore

The DataStore that is associated with the DataQuery.

No exceptions.

Methods

select

Generates a sequence of Property Groups that matches the given selection criteria.

Parameter	Type	Nullable	Optional	Description
query	Object	✔	✘	An associative array containing predicates as keys and objects to match as values. If the query is null, every item in the Data Store that the query is associated with must returned.
template	Object	✘	✔	A template describing the attributes to create in each Property Group that is returned. The template is an associative array containing predicates as keys and attribute names that should be created in the returned PropertyGroup as values.

No exceptions.

Return type: Sequence[PropertyGroup]

Attributes

context of type DataContext, readonly

The default DataContext for the document.

No exceptions.

parser of type DataParser, readonly

The default DataParser for the document.

No exceptions.

query of type DataQuery, readonly

The default DataQuery for the document.

No exceptions.

store of type DataStore, readonly

The default DataStore for the document.

No exceptions.

Methods

createContext

Creates a DataContext and returns it.

No parameters.

No exceptions.

Return type: DataContext

createParser

Creates a DataParser of the given type and returns it.

Parameter	Type	Nullable	Optional	Description
type	DOMString	✘	✘	The type of DataParser to create. For example: "rdfa".
store	DataStore	✘	✘	The DataStore to associate with the DataParser.

No exceptions.

Return type: DataParser

createQuery

Creates a DataQuery for the given store.

Parameter	Type	Nullable	Optional	Description
store	DataStore	✘	✘	The DataStore to associate with the DataQuery.

No exceptions.

Return type: DataQuery

createStore

Creates a DataStore of the given type and returns it.

Parameter	Type	Nullable	Optional	Description
type	DOMString	✘	✘	The type of DataStore to create.

No exceptions.

Return type: DataStore