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Re: Official response to RDF-ISSUE-132: JSON-LD/RDF Alignment

From: Sven R. Kunze <sven.kunze@informatik.tu-chemnitz.de>
Date: Sat, 08 Jun 2013 17:12:40 +0200
Message-ID: <20130608171240.Horde.kiJ1qjG0VUs1P-4mTCtWvQ1@mail.tu-chemnitz.de>
To: Markus Lanthaler <markus.lanthaler@gmx.net>
Cc: 'public-rdf-comments' <public-rdf-comments@w3.org>
Hi,

maybe, the perspective of a potential user helps:

JSON-LD came to my attention in some discussions about problems in  
RDF, Linked Data etc. recently.
I thought some those arguing of how bad RDF is mess up with syntaxes,  
serializations, formats and so on; just missing the point that RDF is  
in fact serialization agnostic.
However, JSON-LD now was there and I read the specs.

First, I thought, hmmm, what's this all about, yet another  
serialization for RDF? Something even better?
To be honest, I didn't spent to much time on the intro as they are  
always quite superficial; especiall when it comes to buzz words like  
Linked Data.

I read the syntax part and thought, okay, yet another serialization  
for RDF, quite verbose with all this JSON []s and {}s, acceptable for  
Web clients as they already have JSON parsers. But no mentioning of  
RDF so far.

BUT the "JSON-LD data model" has been mentioned. Whoooops, now, I was  
confused because RDF is a data model.
So, I read part "data model" and the part "relationship JSON-LD to RDF"
Again, I became more and more confused.
My preliminary conclusion: <<<It's just the same as we can do the same  
with both.>>>
Correct me if I am wrong but having "native literals" does not make  
any difference as most RDF tools and JSON-LD tools will give me a  
variable filled with a datatype specific to the programming language I  
use. I really do not care of the serialization as the work on the data  
is done in code.
So, it gives me the impression that JSON-LD is just another  
serialization for RDF... But why a different data model?

> We added the Data Model section since the RDF WG asked us to do so. I don't
> see compelling reasons to revisit that decision.

I do not question the decision of the RDF WG but for me as a user it's  
quite confusing as it does not contribute any significant advantage  
(at least for me and my understanding of the spec). It in fact  
introduce a steeper learning curve figuring out the differences of  
both data models but from a practical point of view do not exist.


>>>> 4. Make editorial changes to avoid implying that JSON-LD is not RDF.
>>>>   For example, change "Convert to RDF" to "Convert to Turtle" or
>>>> perhaps "Convert to RDF Abstract Syntax".
>>>
>>> The group agrees with changing the title of the section to "Convert to
>>> RDF Abstract Syntax".
>>
>> Thank you.  But there are several other places also where the wording
>> implies that JSON-LD is not RDF.  Appendix C is rife with them. I
>> started to list them, but immediately ran into the problem that this
>> section -- particularly the part before C.1 -- needs to be rewritten
>> once JSON-LD is actually a normative serialization of RDF, and is fully
>> grounded in the RDF model.
>
> JSON-LD is not RDF. Turtle is neither. Both are serialization formats with a
> mapping to RDF, an abstract data model.

Thank you for that clarification!!! Finally, I got it. But why the  
heck isn't the spec mentioning it?

Just to make my point clear: it took me a while to realize the  
importance of the separation of concrete syntax and abstract syntax  
that the RDF data model introduced. It is an so important step, but  
the JSON-LD spec is so blurring?, covering up? a lot that I couldn't  
figure it out on my own what role exactly JSON-LD is supposed to take  
in the Semantic Web AND what its relationship to RDF really is.

Would adding your CLEAR statement ("JSON-LD is a concrete syntax of  
RDF.") to the part "relationship" or even in the intro as the first  
line as e.g. turtle does do any harm?



I am going to support JSON-LD (especially when it comes to processing  
on Web client side; currently, we have such a use-case) and promote it  
to my fellow colleagues. But as long as am I not able to make clear  
statements of how everything fits together, I feel like an idiot  
talking drivel.


Cheers,
Sven
-- 
Sven R. Kunze
Chemnitz University of Technology
Department of Computer Science
Distributed and Self-organizing Systems Group
Stra├če der Nationen 62
D-09107 Chemnitz
Germany
E-Mail: sven.kunze@informatik.tu-chemnitz.de
WWW: http://vsr.informatik.tu-chemnitz.de/people/kunze
Phone: +49 371 531 33882
Received on Saturday, 8 June 2013 15:13:04 UTC

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