Turtle (syntax)
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| Filename extension | .ttl |
|---|---|
| Internet media type | text/turtle |
| Developed by | Dave Beckett |
| Type of format | Semantic Web |
| Container for | RDF data |
| Extended from | N-Triples |
| Standard | Specification |
Turtle (Terse RDF Triple Language) is a format for expressing data in the Resource Description Framework (RDF) data model with a syntax similar to SPARQL. RDF, in turn, represents information using "triples", each of which consists of a subject, a predicate, and an object. Each of those items is expressed as a Web URI.
Turtle provides a way to group three URIs to make a triple, and provides ways to abbreviate such information, for example by factoring out common portions of URIs. For example:
<http://example.org/person/Mark_Twain>
<http://example.org/relation/author>
<http://example.org/books/Huckleberry_Finn> .
History
Turtle was defined by Dave Beckett as a subset of Tim Berners-Lee and Dan Connolly's Notation3 (N3) language, and a superset of the minimal N-Triples format. Unlike full N3, which has an expressive power that goes much beyond RDF, Turtle can only serialize valid RDF graphs. Turtle is an alternative to RDF/XML, the originally unique syntax and standard for writing RDF. As opposed to RDF/XML, Turtle does not rely on XML and is generally recognized as being more readable and easier to edit manually than its XML counterpart.
SPARQL, the query language for RDF, uses a syntax similar to Turtle for expressing query patterns.
In 2011, a working group of the World Wide Web Consortium (W3C) started working on an updated version of RDF, with the intention of publishing it along with a standardised version of Turtle. This Turtle specification was published as a W3C recommendation on 25 February 2014.[1]
A significant proportion of RDF toolkits include Turtle parsing and serializing capability. Some examples of such toolkits are Redland, Sesame, Jena and RDFLib.
Example
The following example defines 3 prefixes ("rdf", "dc", and "ex"), and uses them in expressing a statement about the editorship of the RDF/XML document:
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix dc: <http://purl.org/dc/elements/1.1/> .
@prefix ex: <http://example.org/stuff/1.0/> .
<http://www.w3.org/TR/rdf-syntax-grammar>
dc:title "RDF/XML Syntax Specification (Revised)" ;
ex:editor [
ex:fullname "Dave Beckett";
ex:homePage <http://purl.org/net/dajobe/>
] .
(Turtle examples are also valid Notation3).
The example encodes an RDF graph made of four triples, which express these facts:
- The W3C technical report on RDF syntax and grammar has the title RDF/XML Syntax Specification (Revised).
- That report's editor is a certain individual, who in turn
- Has full name Dave Beckett.
- Has a home page at a certain place.
Here are the triples made explicit in N-Triples notation:
<http://www.w3.org/TR/rdf-syntax-grammar> <http://purl.org/dc/elements/1.1/title> "RDF/XML Syntax Specification (Revised)" . <http://www.w3.org/TR/rdf-syntax-grammar> <http://example.org/stuff/1.0/editor> _:bnode . _:bnode <http://example.org/stuff/1.0/fullname> "Dave Beckett" . _:bnode <http://example.org/stuff/1.0/homePage> <http://purl.org/net/dajobe/> .
The MIME type of Turtle is text/turtle. The character encoding of Turtle content is always UTF-8.[2]
Named Graphs
TriG RDF syntax extends Turtle with support for named graphs.
