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Re: Potential Formal Object from DERI over JSON-LD

From: David Wood <david@3roundstones.com>
Date: Thu, 18 Oct 2012 15:21:37 -0400
Message-Id: <84DB0210-D99F-42ED-A1EF-192E18DD605D@3roundstones.com>
Cc: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>, Michael Hausenblas <michael.hausenblas@deri.org>, RDF WG <public-rdf-wg@w3.org>
To: Gregg Kellogg <gregg@greggkellogg.net>
On Oct 18, 2012, at 14:35, Gregg Kellogg <gregg@greggkellogg.net> wrote:

> One more point on this, Manu and I have slightly different perspective on JSON-LD's relationship with RDF. Manu's use case is to work entirely within JSON-LD, without requiring a transformation to the RDF data model.

I do (really) understand what you are saying, but it is a by odd way to say it (according to me).  One does not ever transform a serialization to a data model.  Instead, one thinks of a serialization as being compliant with a data model or not. Alternately, one thinks of a serialization being convertible to another serialization format that shares the same data model.  Right?

So, it makes sense to me that Manu wants to work with JSON-LD without ever converting it to some other RDF representation such as Turtle or storing it in a database. Fine.  However, if his JSON-LD documents *may* (however theoretically) be converted losslessly to Turtle or parsed into an RDF database because they share a data model, then it is an RDF serialization format.

Does that help level set terms for this discussion or just sound like lecturing?  I hope the former.

Regards,
Dave


> My own use at Wikia also includes this; developers don't actually need to transform the JSON-LD to RDF in order to work with it; that's sort of the whole point! However, this does not mean that JSON-LD is not RDF. Some developers work with RDFa without actually converting it to the RDF data model:
> 
> * Facebook's OGP model famously abuses property IRIs, and avoided the actual definition of the ogp prefix. This was addressed in RDFa 1.1 by including "ogp" as a prefix in the default context, and ensuring that IRIs containing multiple colon's (":") were legitimate; I think Turtle made the same change.
> 
> * Niklas Lindström has an RDFa to JSON-LD converter [1], that does not need to go through an intermediate RDF model representation form (AFAIK).
> 
> I think it's perfectly reasonable for developers to work entirely within the JSON-LD space without requiring a transformation to the RDF data model do do anything. The fact that the data _is_ RDF, and can be converted to the RDF data model is a plus. In my own case, I want to be able to transform the JSON-LD objects to RDF so that I can perform OWL entailments to infer data relationships not necessarily managed directly through the JSON-LD definitions. The fact that I can allow developers to work entirely within JSON, and give them back a representation that includes the entailed relationships is quite important. Also, I can mark-up OWL class definitions with other more explicit subClass/superClass/property-list information to allow for form validation, when using a JSON-LD representation of the vocabulary. All I'm really doing is creating entailment rules that allow me, for example, to determine all of the properties that have an effective domain of a given class, taking into consideration rdfs:subClassOf and owl:unionOf semantics.
> 
> JSON-LD is solving real-world problems at Wikia, and should lead to a time when hundreds of thousands of wikis are available as linked data, due to the strength and flexibility of the RDF ecosystem.
> 
> Gregg Kellogg
> gregg@greggkellogg.net
> 
> [1] https://github.com/niklasl/rdfa-lab
> 
> On Oct 18, 2012, at 7:02 AM, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
> 
>> There are two questions that I have continued to have about JSON-LD.
>> 
>> 1/ Is JSON-LD a serialization syntax for all RDF graphs?
>> 2/ Is JSON-LD only a serialization syntax for RDF graphs?
>> 
>> Could the interested parties state straight up their answers to these questions?
>> 
>> 
>> The opinions below are mine alone.  I have included them here to give some 
>> rationale as to why I want answers to the above questions to be on record.
>> 
>> If the answer to the second question is true, i.e., every JSON-LD structure 
>> corresponds to an RDF graph and there is no more information in the JSON-LD 
>> structure, then it is obvious to me that JSON-LD work should go forward in the 
>> RDF WG.
>> 
>> If the answer to the first question is true, i.e, every RDF graph can be 
>> written as a JSON-LD structure and recovered from that structure unchanged, 
>> but not the second, then the situation is somewhat murky.  It seems to me that 
>> there should be some convincing argument why the RDF WG is recommending 
>> something larger than RDF, and the more there is in JSON-LD (ordering, etc., 
>> etc.) the more convincing this argument has to be.  In this case it may be 
>> better to have some other status for the JSON-LD documents, or even for the 
>> RDF WG to simply point to the JSON-LD documents in one of its documents.
>> 
>> If neither are true, then I don't see any reason for the RDF WG be interested 
>> in JSON-LD.
>> 
>> Peter F. Patel-Schneider
>> 
>> 
>> 
> 
Received on Thursday, 18 October 2012 19:22:12 GMT

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