The document summarizes the work of the W3C RDF Working Group to update RDF 1.1. The group aims to break as little as possible while reflecting real-world experiences. Key areas of focus include new datatypes, string literals, blank nodes, serializations like Turtle, N-Triples, and JSON-LD, and addressing challenges around graphs. The progress, challenges, and participants are also outlined.

1. David Wood
Updating RDF co-chair, W3C RDF Working Group
June 2012
Wednesday, May 30, 12

2. Charter
•Define RDF 1.1
•Break as little as possible.
•Reflect real-world experiences back into the
standards.
http://www.w3.org/2011/rdf-wg/
Wednesday, May 30, 12

3. Out of Scope
•Changing the fundamentals of RDF(S) semantics
•Removing current restrictions in the RDF model
(e.g., literals not allowed as subjects, or blank
nodes as predicates)
Wednesday, May 30, 12

4. Comment
RDF is the data model;
More standard serializations will help show that.
Wednesday, May 30, 12

5. Documents
• RDF 1.1 Concepts and • (New) Turtle
Abstract Syntax
• (New) N-triples
• RDF 1.1 Semantics
• (New) JSON-LD
• RDF 1.1 Primer
• (Minor changes) RDF/XML
Syntax Specification
• (Minor changes) RDF
Vocabulary Description
Language 1.1: RDF Schema
Wednesday, May 30, 12

6. RD
FW
G
X
Oh, hey, I didn’t
Can we just change see you guys all
Who’s
the spec so I can Everything can Graphs can’t be labile the way over there
that? be a resource
implement it? and I’m not either
Users Web Framework RESTifarians Logicians Mathematicians
Coders Coders
Thanks and apologies to xkcd
Wednesday, May 30, 12

7. e r s
a i m
s cl
D i
Wednesday, May 30, 12

8. Progress
•Turtle, First Public Working Draft, 2011-08-09
•RDF 1.1 Concepts and Abstract Syntax, First
Public Working Draft, 2011-08-30
•XSD 1.1 usage
•Lots of lessons learned regarding use cases,
concerns and expectations.
Wednesday, May 30, 12

9. Progress
•Current list of resolutions:
http://demo.3roundstones.net/rdf/2012/rdfwg/
resolutions.xhtml?view
•Closed issues:
http://www.w3.org/2011/rdf-wg/track/issues/
closed
Wednesday, May 30, 12

10. Challenges
•Graphs
•Charter: “Standardize a model and semantics
for multiple graphs and graphs stores”
•This is the most contentious portion of our
work because it has the potential to radically
change RDF, which we are not chartered to do.
Wednesday, May 30, 12

11. Graphs
•A “Graph Container” is a container, like a mutable
“set” data structure in programming. It holds some
RDF triples.
•An “RDF Graph” is an idealized snapshot of a
Graph Container; it's a mathematical set of RDF
triples.
•A “Graph Serialization” is a particular sequence
of characters or bytes which conveys a particular
RDF Graph in a language (e.g. Turtle or JSON-LD).
Wednesday, May 30, 12

12. Blank Nodes
•Many RDF users avoid using blank nodes. In some
circles, this is considered to be a best practice.
•Some issues raised by the use of blank nodes are how
they may be followed (e.g. in SPARQL result sets) or
referenced (e.g. within the same RDF document).
•Optionally Skolemize blank nodes when desired.
Wednesday, May 30, 12

13. Blank Nodes
• In situations where bNode identification is needed, systems may
systematically transform some or all of the blank nodes in an RDF
graph into new, globally unique IRIs (Skolem IRIs).
• For example, the authority responsible for the domain
example.com could mint the following recognizable Skolem IRI:
http://example.com/.well-known/genid/
d26a2d0e98334696f4ad70a677abc1f6
• Makes bNodes useful in the same way that auto_increment
columns in SQL are.
Wednesday, May 30, 12

14. New Datatypes
• Added new RDF-compatible XSD 1.1 datatypes:
• xsd:duration
• xsd:dayTimeDuration
• xsd:yearMonthDuration
• xsd:dateTimeStamp
Wednesday, May 30, 12

15. String Literals
•All literals are typed. “Typed literal” becomes redundant.
•“foo” becomes syntactic sugar for “foo”^^xsd:string.
• Systems SHOULD silently convert xsd:string data to plain
literals on output.
• The RDF WG is recommending to the SPARQL WG and other
SemWeb WG’s that they do the same.
• Literals with a language tag now have the datatype IRI
rdf:langString.
Wednesday, May 30, 12

16. rdf:XMLLiteral
•XMLLiterals will be optional.
•The lexical space consists of well-formed XML
fragments.
•The canonical lexical form is http://www.w3.org/TR/
xml-exc-c14n/, as defined in RDF 2004 (no longer
requires lexical forms to be canonicalized).
•The value space consists of a set of DOM4
DocumentFragment nodes.
Wednesday, May 30, 12

17. rdf:HTML
•rdf:HTML literals will be introduced.
•The lexical space consists of the set of Unicode
strings.
•The value space consists of a set of DOM4
DocumentFragment nodes.
•Two DocumentFragment nodes A and B are
considered equal if and only if the DOM4 method
A.isEqualNode(B) returns true.
Wednesday, May 30, 12

18. New RDF Serializations
•Turtle:
•Changed very little.
•Turtle / SPARQL syntax harmonisation
•N-Triples:
•Orginally defined only for RDF test cases, n-triples
will be standardized primarily for use as a bulk
loading syntax.
•JSON-LD (probably)
Wednesday, May 30, 12

19. (Minor) Changes to Turtle
•ISSUE-1: Turtle / SPARQL harmonization
•‘.’s and ‘:’ in names in all positions of a local name
apart from the first or last, e.g.
ex:first.name / ns:foo:bar
•Escape characters in prefixed names, e.g.
ex:resource/thing123 / ex:thing123#this
•Digits in the first character of local names, e.g.
ex:7tm
Wednesday, May 30, 12

20. (Minor) Changes to Turtle
•Floats require a decimal after the ‘.’, e.g.
ex:subject ex:hasValue “18.0” .
(so you no longer need a space before the trailing ‘.’)
•Adopted case-sensitive constants for xsd:boolean
true and false.
Wednesday, May 30, 12

21. (Minor) Changes to Turtle
•At risk feature:
•SPARQL:
PREFIX dc: <http://purl.org/dc/terms/>
•Turtle:
@prefix dc: <http://purl.org/dc/terms/> .
or
prefix dc: <http://purl.org/dc/terms/>
(case insenstive, like SPARQL)
Wednesday, May 30, 12

22. Turtle
•HTML5:
<script type="text/turtle">
@prefix frbr: <http://purl.org/vocab/frbr/core#> .
<http://books.example.com/works/45U8QJGZSQKDH8N> a frbr:Work .
</script>
•XHTML:
<script type="text/turtle">
# <![CDATA[
@prefix frbr: <http://purl.org/vocab/frbr/core#> .
<http://books.example.com/works/45U8QJGZSQKDH8N> a frbr:Work .
# ]]>
</script>
Wednesday, May 30, 12

23. N-triples
•Now UTF-8
•Shifted to IRIs, not RDF URI References
•Media type: application/rdf-triples
•Tied closely to the Turtle grammar
Wednesday, May 30, 12

24. JSON-LD
•JSON-LD developed away from the RDF WG, now
back (see http://json-ld.org)
•JSON-LD is a language capable of serializing any
RDF graph, and performing full RDF to JSON-LD to
RDF round-tripping.
•Working Draft stage, but more mature than most
(e.g. implementations exist)
•Concerns: (Perceived lack of WG JS knowledge)
Wednesday, May 30, 12

25. JSON-LD
{
"@context": "http://json-ld.org/contexts/person",
"@id": "http://dbpedia.org/resource/John_Lennon",
"name": "John Lennon",
"birthday": "10-09",
"member": "http://dbpedia.org/resource/The_Beatles"
}
Wednesday, May 30, 12

26. The RDF Working Group is:
Jean-François Baget Fabien Gandon Nathan Rixham
Thomas Baker Charles Greer Guus Schreiber
Adrien Basse Alex Hall Andy Seaborne
Scott Bauer Steve Harris Manu Sporny
Aidan Boran Michael Hausenblas Thomas Steiner
Dan Brickley Sandro Hawke Mouhamadou Thiam
Matteo Brunati Patrick Hayes Ted Thibodeau
Gaoussou Camara Ivan Herman Thomas Visel
Gavin Carothers Nicholas Humfrey William Waites
Jeremy Carroll Kingsley Idehen Jan Wielemaker
Pierre-Antoine Champin Arnaud Le Hors David Wood
Kiu Ching Dickson Lukose Zhe Wu
Olivier Corby Ivan Mikhailov Mohamed Zergaoui
Richard Cyganiak Peter Patel-Schneider Antoine Zimmermann
Souripriya Das Eric Prud'hommeaux
Lee Feigenbaum Yves Raimond
Wednesday, May 30, 12

27. David Wood
Updating RDF co-chair, W3C RDF Working Group
June 2012
Wednesday, May 30, 12