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Re: Potential Formal Object from DERI over JSON-LD

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Fri, 19 Oct 2012 10:43:56 -0400
Message-ID: <5081672C.7090808@digitalbazaar.com>
To: RDF WG <public-rdf-wg@w3.org>
On 10/19/2012 12:04 AM, Peter F. Patel-Schneider wrote:
> The technical issues are not as problematic as I had thought.

Good to hear. :)

> The presentation issues, however, are quite a bit worse that I had 
> thought would be the case by now.  The draft of 16 Oct scarcely 
> mentions RDF.  It restates a whole lot of the basic definitions of 
> RDF, and even in ways that obscure the relationship between JSON-LD 
> and RDF.  The draft of 18 Oct appears to be somewhat better, but not 
> (yet) by much.

These changes were requested by Richard Cyganiak and made to the spec
text. He is also working on the RDF Concepts/JSON-LD alignment:


> I state that the JSON-LD Syntax document MUST not only align with RDF
> but MUST also utilize the RDF definitions (particularly from RDF 
> concepts).   The vague promises in the document are wholly 
> inadequate; the change needs to happen well before last call, as it 
> is a major change.

We're working on it (above). If you have specific changes, you should
log them in the issue above or have a lengthy discussion with Richard.
I'm also available to talk about it in detail. You are also invited to
join us on the JSON-LD telecon next week (or any other week) to discuss it:


> For example, LSON-LD MUST be stated as a way of writing down RDF 
> graphs

I was hoping that "Appendix B: Relationship to Other Linked Data Formats
and Data Models" made this clear, does it not? If not, what is the exact
spec text you would like to see?

> (with perhaps a simple generalization, although if linked data does
> not allow bnode properties then I see no reason to allow bnode 
> properties in LSON-LD).

Could you point to a part of the current JSON-LD spec that asserts that
Linked Data does not allow blank-node properties? Why do you think it
would be a good feature of a language capable of round-tripping RDF to
not be able to express bnodes?

> JSON-LD nodes MUST be stated to be RDF nodes.  JSON-LD data values
> MUST be stated to be RDF literals and mention both plain and datayped
> literals.  JSON blank nodes MUST be stated to be RDF blank nodes.

I believe that Richard is working on terminology alignment as we speak.

> All the JSON ordered constructs allowed in JSON-LD MUST be stated to
> be insignificant

What do you mean by "JSON ordered constructs"? Do you mean the concept
of the JSON 'array'? If so, we cover this in "Section 4.9: Sets and Lists".

> and there MUST be a test that tests this

There are a number of tests for @set and @list. I added an issue to
ensure that list order is maintained when round-tripping to/from RDF:


I note that we don't have one for ensuring that a set isn't ordered, but
how do you write that test?

> or MUST have a translation into something in RDF that is ordered, and
> this translation should be prominent in the document.

We support ordered arrays via @list. We support unordered sets via @set.
We support round-tripping of both to and from RDF. All of this is
covered in "Section 4.9: Sets and Lists" of the JSON-LD Syntax spec and
all algorithms that could touch these data structures in the JSON-LD API.

> Examples MUST be stated to be RDF, not linked data.

Which examples? How do we state that an example is RDF (since RDF is
just a data model)?

> In essence, for JSON-LD to progress in the RDF WG, it should align to
> RDF, not linked data!

Could you re-state this in a way that is actionable?

> There should be many more occurrences of "RDF" than "linked data".

Number of times 'RDF' is mentioned in the spec: 59
Number of times 'linked data' is mentioned    : 30

Although, this is a bad metric for any spec, imho.

> Consider the first bit of section 3.1 - it should say RDF in every
> numbered point, except, perhaps, the last.

We're going around in circles. That's where we started two years ago.
Then we went to Linked Data. Then we went to the JSON-LD data model
(after input from the RDF WG). Now you're asking us to go back to RDF in
that section. I'd like the RDF WG group to give us clear direction on
this, taking into account all of the /many/ discussions we've had on
this point.

-- manu

Manu Sporny (skype: msporny, twitter: manusporny)
Founder/CEO - Digital Bazaar, Inc.
blog: The Problem with RDF and Nuclear Power
Received on Friday, 19 October 2012 14:44:30 UTC

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