David and Peter's JSON-LD 1.0 Review Feedback

[lanthaler]

_Feedback by David Booth (and Peter Patel-Schneider):_

These are comments on https://dvcs.w3.org/hg/json-ld/raw-file/default/spec/latest/json-ld-syntax/index.html#relationship-to-rdf

1. JSON-LD should be an RDF syntax, just as Turtle is an RDF syntax. This means: (a) it should define the same data model as RDF -- not a superset; and (b) it should have the same semantics as RDF serialized in any other syntax.

It does not make sense for the W3C to define splinter the RDF market by defining a competing data model that is so similar to RDF and fills the same needs. Section C 'Relationship to RDF' makes clear that JSON-LD defines a different graph model than RDF: "The RDF data model, as outlined in [RDF-CONCEPTS], is an abstract syntax for representing a directed graph of information. It is a subset of JSON-LD's data model".

If the long-term plan for RDF is that it will eventually embrace the additional features of JSON-LD (such as blank nodes as graph names, blank nodes as properties) then the RDF specification itself (and the SPARQL specification?) should be changed NOW to be consistent with JSON-LD,.

1. A JSON serialization of RDF should not require IRIs to be dereferenceable -- even with a "SHOULD" requirement as currently stated:

   IRIs used within a JSON-LD graph should return a Linked Data document
   describing the resource denoted by that IRI when being dereferenced.

Fundamentally this specification should be defining JSON-RDF -- not JSON-LD. There are many RDF applications that are not Linked Data applications but would nonetheless benefit from a JSON serialization of RDF.

However, it would be good to define JSON-LD on top of JSON-RDF, once JSON-RDF is defined.

David

[msporny]

The resolution of the group hasn't changed. JSON-LD supports blank nodes in the predicate and graph name positions. We would have liked the RDF WG to support this extension to the RDF model, but there was too much disagreement in the group. The RDF WG has noted that the approach of having a super-set data model is fine as long as it is clearly documented, which it is.

[msporny]

Response to David Booth:

http://lists.w3.org/Archives/Public/public-rdf-comments/2013Mar/0036.html

[lanthaler]

@msporny can we close this issue or do you think it needs to be further discussed?

[lanthaler]

RESOLVED: Make David Booth's bullet-point addition to the JSON-LD Syntax spec: " * Software developers who want to generate or consume Linked Data, an RDF graph or an RDF Dataset in a JSON syntax."

[lanthaler]

RESOLVED: Add spec text to the following effect into the JSON-LD Syntax specification: JSON-LD was designed to be usable directly as JSON, with no knowledge of RDF, but was designed also to be usable as RDF (if desired), for use with other Semantic Web technologies like SPARQL. People intending to use JSON-LD with RDF tools will find it can be used as another RDF syntax, like Turtle....

[lanthaler]

RESOLVED: Add spec text to JSON-LD Syntax. Appendix C: JSON-LD is a concrete RDF syntax as described in [RDF11_CONCEPTS]. Hence, a JSON-LD document is both an RDF document and a JSON document and correspondingly represents both an instance of the RDF data model and an instance of the JSON-LD data model.

[lanthaler]

RESOLVED: Adopt proposal 2g and replace the first paragraph in the JSON-LD Syntax Introduction with: Linked Data[LINKED_DATA] is a way to create a network of standards-based machine interpretable data across different documents and Web sites. It allows an application to start at one piece of Linked Data, and follow embedded links to other pieces of Linked Data that are hosted on different sites across the Web.

[lanthaler]

RESOLVED: Add an option to produce "extended RDF", which defaults to false. If the option is true, "extended RDF" will be produced, retaining triples that have blank nodes as predicates. If the option is false, standard RDF will be produced and triples with blank node properties will be discarded.

RESOLVED: When mapping properties, if the author is not yet ready to commit to a stable IRI, suggest mapping the property to an IRI that is documented as unstable.

[msporny]

@lanthaler I believe that the only remaining edit needed to fully address David Booth's issues is the 'produceGeneralizedRdf' option/algorithm modification to the JSON-LD API.

[gkellogg]

I was going to look at folding Niklas' changes into the fromRDF algorithm, I can address produceGeneralizedRdf too.