The document summarizes the key changes and additions in the RDF 1.1 specification, including: 1) Support for named graphs, also known as RDF datasets or quads, to represent multiple RDF graphs each with a unique name; 2) Additional datatypes like durations and date/time stamps; 3) JSON-LD as a new syntax for serializing RDF in JSON; and 4) Some controversial proposals like deprecating features and allowing literals as subjects that did not make the final specification.

1. Richard Cyganiak — DERI Friday Talk, 26 July 2013
WHAT'S NEW IN RDF 1.1?

2. World Wide Web Consortium (W3C)
• Standards body responsible for the Web
• DERI is a member
• What W3C can do for you:
Member submissions
– Community Groups
– Work with experts, network, see how the sausage
is made

3. Today
• RDF — A quick overview
• What's new in RDF 1.1?
– JSON-LD
• The controversies and stuff that didn't make it

4. RDF — A quick intro

5. Why RDF?
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A data model for the Web
Can represent data from other data models
Easy to integrate data from multiple sources
Graphs, not tables or trees

6. How it works

7. How it works

8. How it works

9. How it works

10. How it works

11. Foundation for a family of standards
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SPARQL: Querying RDF data
RDF Schema: Documenting the meaning of RDF data
OWL: Formalizing the meaning of RDF data
RDF/XML: Writing RDF data in XML
RDFa: Embed RDF data in HTML
R2RML: Mapping relational data to RDF
GRDDL: Mapping XML data to RDF
DC, Org, FOAF, SIOC, DCAT, VoID, …:
Describe particular domains as RDF data

12. What's new in RDF 1.1?

13. RDF 1.1
• First update since 2004
• RDF-WG started in 2011, expected to end
2013
• Chartered to do:
– Maintenance
– Fixing some well-known issues
– "Paving the cowpaths"
• Nothing new in RDF Schema and RDF/XML

14. RDF datasets
A.k.a Named Graphs, Quads

15. http://svn.foaf-project.org/foaftown/2009/layers/visuals/layercake2.jpg

16. RDF Datasets
• Adopted from SPARQL — "Named Graphs"
• Two data structures:
– RDF graph
– RDF dataset
• Multiple RDF graphs, each named with a URI
• A.k.a “quads”
• Unnamed “default graph”
– can be used for metadata
• Applications:
integration, provenance, versioning, …

17. Datatypes
• xsd:duration, xsd:dayTimeDuration, xsd:yearMonthDuration
• xsd:dateTimeStamp
– Unlike xsd:dateTime, the time zone is not optional
• rdf:langString
– "Hello"@en now has a datatype
• rdf:HTML
– "E=mc²"^^rdf:HTML
– Problem: No language tag!
• rdf:XMLLiteral
– No longer needs to be canonical XML
• xsd:string
– "xxx" and "xxx"^^xsd:string are now 100% the same thing

18. Syntaxes
• Turtle
– Now SPARQL compatible
• TriG
– Turtle with named graphs
• N-Triples
– WG Note
• N-Quads
– WG Note
• JSON-LD

19. JSON-LD

20. {
"id": "markus",
"firstname": "Markus",
"lastname": "Lanthaler",
"homepage": "http://www.markus-lanthaler.com/"
}

21. {
"@context": {
"firstname": "http://schema.org/givenName",
"lastname": "http://schema.org/familyName",
"homepage": "http://schema.org/url"
},
"id": "markus",
"firstname": "Markus",
"lastname": "Lanthaler",
"homepage": "http://www.markus-lanthaler.com/"
}

22. {
"@context": {
"firstname": "http://schema.org/givenName",
"lastname": "http://schema.org/familyName",
"homepage": "http://schema.org/url"
},
"@id": "/people/markus",
"firstname": "Markus",
"lastname": "Lanthaler",
"homepage": "http://www.markus-lanthaler.com/"
}

23. {
"@context": {
"firstname": "http://schema.org/givenName",
"lastname": "http://schema.org/familyName",
"homepage": "http://schema.org/url"
},
"@id": "/people/markus",
"firstname": "Markus",
"lastname": "Lanthaler",
"homepage": "http://www.markus-lanthaler.com/"
}

24. {
"@context": {
"firstname": "http://schema.org/givenName",
"lastname": "http://schema.org/familyName",
"homepage": "http://schema.org/url"
},
"@id": "/people/markus",
"firstname": "Markus",
"lastname": "Lanthaler",
"homepage": { "@id": "http://www.markus-lanthaler.com/" }
}

25. {
"@context": {
"firstname": "http://schema.org/givenName",
"lastname": "http://schema.org/familyName",
"homepage":
{"@id": "http://schema.org/url", "@type": "@id" },
},
"@id": "/people/markus",
"firstname": "Markus",
"lastname": "Lanthaler",
"homepage": "http://www.markus-lanthaler.com/"
}

26. {
"@context": {
"firstname": "http://schema.org/givenName",
"lastname": "http://schema.org/familyName",
"homepage":
{"@id": "http://schema.org/url", "@type": "@id" }
},
"@id": "/people/markus",
"@type": "http://schema.org/Person",
"firstname": "Markus",
"lastname": "Lanthaler",
"homepage": "http://www.markus-lanthaler.com/"
}
Example from Markus Lanthaler,
http://www.slideshare.net/lanthaler/building-next-generation-web-ap-is-with-jsonld-and-hydra

27. The controversies
and stuff that didn't make it

28. Deprecating some of the bad stuff
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Reification
rdf:Alt, rdf:Bag, rdf:Seq
RDF/XML 
rdf:value
For every bad feature, there is a vocal user
who can't live without it

29. Literals as subjects
• 1 math:lessThan 2
• "2013"^^xsd:gYear time:isBefore "2014"^^xsd:gYear
• "Galway" ex:isTitleOf<http://dbpedia.org/resource/Galway>
• Most specs and implementations could be
easily adapted to allow this
• Not worth it

30. Semantics of RDF datasets
• What logical statements does an RDF dataset
make?
– How can we reason over them?
• In a named graph, what is the relationship
between the graph name URI and the RDF graph?
– Same as? Is described by? Contains?
• No solution fits all use cases. It's left unspecified.
– No standard way to reason over RDF datasets

31. Nested and anonymous graphs
• What about: "Bob said that Alice said XXX"?
• Should we allow graphs as a new type of node
in RDF triples?
– URIs, literals, blank nodes, RDF graphs
• Little implementation experience (but N3!)
• Requires new DBs, different query language