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Re: JSON-LD Syntax request for FPWD via RDF WG

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Tue, 22 May 2012 21:21:10 -0400
Message-ID: <4FBC3B86.7000505@digitalbazaar.com>
To: RDF Comments <public-rdf-comments@w3.org>
CC: 'Linked JSON' <public-linked-json@w3.org>
On 05/22/2012 10:42 AM, Richard Cyganiak wrote:
> Is there a particular reason why the RDF mapping is in the API spec
> rather than in the language spec?

The API spec is where the toRDF() and fromRDF() methods are specified.
There are examples at the bottom of the JSON-LD Syntax spec that explain
how to express things written in TURTLE, RDFa, Microformats and
Microdata in JSON-LD. However, explaining every feature of mapping the
RDF model to JSON-LD is not a priority for that spec.

That said, you will note that the JSON-LD specification does actually
cover how one expresses IRIs, literals, literals with language, typed
literals, lists, and all other RDF model features in the spec. We just
don't explicitly state that they came from the RDF model (because, in
reality - they didn't - they came from the Linked Data model... which
borrows heavily from the RDF model). They're effectively the same thing,
but the distinction we're making is this: JSON-LD stands on its own...
you don't need to understand RDF to use it.

> Is the proposal that RDF-WG should take both the API spec and the
> language spec to REC?

The RDF WG should take the JSON-LD Syntax spec to REC. The JSON-LD API
spec does not have a home right now... it could be this group, or it
could be the job of a re-chartered RDF Web Apps WG. That decision is up
in the air right now... and the JSON-LD API spec needs more
implementation experience before we take it to LC.

> At first glance, these sections look great. I notice three things
> though:
> 1. I'd prefer if the algorithms were defined in terms of standard RDF
> terminology (RDF graph, triple, IRI, etc.) rather than API interfaces
> that use quite different terminology (array of Statements, Statement,
> NamedNode, etc.)

RDF graph - maybe. triple - absolutely not, since a Statement is
effectively a quad. IRI - yes, if we don't do that - it's a bug. The API
interfaces use things like "Statement" and "NamedNode" because that's
what we call the concepts via the WebIDL in the spec. We could change
some of the WebIDL to match the language in the RDF Concepts document,
if it makes sense to do so. Also note that many of these names came from
the RDF API spec.

Whatever we do, I think we should be consistent (not that I think anyone
is arguing against consistency). The API spec has not had the same
amount of review that the JSON-LD Syntax spec has, so I wouldn't say
that it's ready for a thorough vetting at this point. It should give you
a good idea of the direction in which we're headed, though.

> 2. Examples would be great.

Agreed, added a bug:


> 3. Is it possible to serialize an RDF graph into a “pretty” JSON-LD
> document using a context?

Yes, absolutely.

> I presume the answer is “yes” and involves Compaction of the basic
> serialized output.

Yep. You could also frame the RDF graph if you only wanted a subset of
it as well.

>> Btw. I can't join the RDF WG mailing list. Is there anything I must
>> know?
> I believe that the list is members-only (with public archive). I
> don't know why. There is an open comments list here, which is
> generally better if non-WG-members are involved:
> http://lists.w3.org/Archives/Public/public-rdf-comments/

I think it's vital that the following three editor/contributors to the
JSON-LD spec are added to this group as Invited Experts: Gregg Kellogg,
Niklas Lindström, and Markus Lanthaler. These three are intimately
familiar with JSON-LD and have been on just about every JSON-LD telecon
since the JSON for Linking Data Community Group was started.

Talking about JSON-LD on public-rdf-comments cripples the discussion
because I don't think that many of the RDF WG members check this mailing
list (as evidenced by the relative lack of activity on this list).

-- manu

Manu Sporny (skype: msporny, twitter: manusporny)
Founder/CEO - Digital Bazaar, Inc.
blog: PaySwarm Website for Developers Launched
Received on Wednesday, 23 May 2012 01:22:25 UTC

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