W3C home > Mailing lists > Public > public-rdf-comments@w3.org > April 2013

Re: JSON-LD should be an RDF syntax

From: David Booth <david@dbooth.org>
Date: Mon, 29 Apr 2013 18:44:07 -0400
Message-ID: <517EF7B7.9070208@dbooth.org>
To: Kingsley Idehen <kidehen@openlinksw.com>
CC: public-rdf-comments@w3.org
On 04/29/2013 03:59 PM, Kingsley Idehen wrote:
> On 4/29/13 1:51 PM, David Booth wrote:
>>>> Apparently it was not entirely resolved.
>>>
>>> It was resolved, hence the definition in place today.
>>
>> It clearly has *not* been resolved, as: (a) we are still discussing
>> it; (b) there obviously is major contention; and (c) the definition in
>> the current draft substantially conflicts with the original sense of
>> the term and with established usage.
>
> It has been resolved on the JSON-LD side of things, to be clear.

Not true.  First, I see no such issue listed at all on the LDP working 
group issue tracker, whether open or closed:
http://www.w3.org/2012/ldp/track/issues
Second, the JSON-LD spec as a whole is only in draft status.  It is far 
from resolved.

> I have
> no idea what the state of play is on the RDF groups side of things, I do
> know that you are a single voice of dissent at this point in time though.

For goodness sake, you just heard *two* voices of dissent in less than 
10 hours!

Furthermore:

  - Of the top 10 hits from in a google search for "Linked Data", 
**every one of them stated or implied that Linked Data is based on RDF.**

  - Of the top 10 sites listed in a google search for '"Linked Data" 
is', **every one of them stated or implied that Linked Data is based on 
RDF.**

  - Of the top 10 sites listed in a google search for '"Linked Data" 
definition', **every one of them stated or implied that Linked Data is 
based on RDF.**

How much evidence do you need?  Shall we check the top 100 hits?  Or the 
top 1000 hits?  Shall we try other search engines?   If you search hard 
enough you might find a tiny fraction that supports your claim.  But the 
vast majority of the evidence does not.

The vast majority of the evidence indicates that in established usage, 
the term "Linked Data" implies the use of RDF.  If you wish to propose a 
new definition that is contrary to this established usage, you are 
obviously free to do so.  But please do *not* make the patently false 
claim that your proposed new definition reflects accepted usage.  It 
very clearly does NOT.

>
>>
>>>
>>>>
>>>>> RDF and Linked Data are not the same thing.
>>>>
>>>> Of course not.  Linked Data (in its original sense) *builds* on RDF
>>>> and other standards, most notably HTTP.
>>>
>>> Sorta.
>>>
>>> Linked Data is something you can produce using RDF and associated
>>> standards.
>>>
>>>>
>>>>> Linked Data is something that you can
>>>>> produce (5-star quality) using RDF.
>>>>
>>>> Yes.
>>>>
>>>
>>> Good, we are agreeing so far.
>>>
>>>>> TimBL's meme is all about a
>>>>> principled approach to producing Web-scale Linked Data that leverages
>>>>> standards such as RDF and SPARQL.
>>>>
>>>> Exactly.
>>>>
>>>>> That doesn't imply that the meme owns the phrase "Linked Data.
>>>>
>>>> The term was coined specifically for that purpose.  AFAIK there is no
>>>> legal ownership of the term, so we're talking moral ownership here --
>>>> not legal.  The point is that attempting to redefine this term is
>>>> harmful to the Semantic Web community, because it creates confusion
>>>> about what "Linked Data" means.  And that is harmful to W3C's mission.
>>>
>>> TimBL cleverly generated a meme using a quite generic phrase. The
>>> original meme (the one that had no RDF or SPARQL references) was totally
>>> GOLDEN re., blending Open Data and Web Architecture.
>>>
>>> The meme got itself into trouble the moment RDF and SPARQL where added
>>> to its most recent revision, for the totally wrong reasons. This
>>> revision lay the foundation for RDF and Linked Data conflation. It took
>>> a GOLDEN meme and turned it into a vector for the same old political
>>> distractions that come with RDF (which is generally misunderstood).
>>>>
>>>>>
>>>>> Over extending what RDF is remains its ultimate problem. RDF doesn't
>>>>> have to cloud the definition of everything in order for it to be
>>>>> useful :-)
>>>>
>>>> That's directly backwards.  What's clouding the definition is *not*
>>>> RDF, but the attempt to redefine the term "Linked Data" to mean
>>>> something different than what it was specifically coined to mean:
>>>> http://www.w3.org/standards/semanticweb/data
>>>> http://www.w3.org/DesignIssues/LinkedData.html
>>>
>>> RDF does not imply Linked Data,
>>
>> Of course not.  The implication is the other way around: Linked Data
>> (in the original, established sense of the term) implies RDF.
>
> Linked Data doesn't imply RDF at all.

Apparently it doesn't in *your* mind.  But in the established sense of 
the term, "Linked Data" very clearly *does* imply RDF.

>
> Linked Data simply implies that a URI resolves to a Document that
> describes its referent.
>
> RDF based Linked Data implies the above, plus the fact that the Document
> is comprised of RDF based content [1][2].
>
>>
>>> most RDF resource out in the wild
>>> (modulo LOD cloud datasets) don't even conform to Linked Data principles
>>> in the slightest.
>>
>> Right.
>>
>>> Re-read this thread and I think you will see that you
>>> got "backwards" completely backwards.
>>
>> I am amazed that you think so.  If you can show me evidence, then
>> perhaps I can figure out why we seem to be miscommunicating so badly.
>> At present I am mystified.
>
> As per my comments above, there are links to illustrations of RDF based
> Linked Data URIs which convey the critical aspects of RDF based Linked Data.
>
> Please note, the entity relationship model precedes any notion of RDF
> [3]. The contribution made by RDF is as follows:
>
> 1. URIs as denotation mechanism for entities
> 2. Explicit rather than implicit entity relationship semantics --
> discernible to humans and machines.
>>
>>>
>>> RDF is a poor understood composite of:
>>>
>>> 1. Data Model
>>> 2. Data Model Syntax
>>> 3. Data Model Syntax Notations
>>> 4. Data Serialization Formats -- the product of processors transforming
>>> Syntax Notation into raw data for storage or across-the-write transfer.
>>
>> Please do not conflate RDF with its syntax or serializations. Many who
>> are new to RDF make this mistake.
>
> I am not making a mistake. A simple example:
>
> ## Turtle ##
>
> <> a <#Document> .
>
> ## End ##
>
> The above is an example of syntax notation. Note how the notation allows
> the use or relative URIs. That's syntax notation for expressing an RDF
> model graph using Turtle.
>
> A Turtle processor will not output an RDF graph serialization with
> relative URIs, such a thing is an invalid RDF graph.

Turtle is a syntax for serializing RDF.  It uses many syntactic 
conventions that are not a part of the RDF model, including square 
brackets, parentheses for lists, "@prefix" declarations, and relative 
URIs.  The fact that those syntactic elements do not appear in the RDF 
model is irrelevant.

>
>> It is harmful to perpetuate this misunderstanding.
>
> Who is perpetuating any kind of misunderstanding here? You have a simple
> Turtle example that backs up my point.

No, Turtle is a syntax for serializing RDF.

>
> RDF has SPO based 3-tuples as its syntax.
>
> Turtle is an example of notation for expressing those 3-tuples.
>
> The final RDF graph is the product of processors that understand one or
> more syntax notations en route to producing actual RDF graphs.

Right: Turtle is a syntax for serializing RDF.  The Turtle serialization 
is *not* the same as the actual RDF.

>
>>
>> RDF may be poorly understood to many developers, but that is
>> irrelevant, as many technologies are poorly understood to many
>> developers.
>
> It isn't irrelevant. RDF has taking a simple concept and turned it into
> a riddle, for all the wrong reasons.
>
>> But RDF is *not* poorly understood from a technical perspective: it is
>> a W3C standard and is very clearly defined.
>
> No comment. I think that statement speaks for itself with regards to
> actual reality.
>
>>
>>>
>>> Nothing in the RDF specs mandates that URIs or IRIs must resolve.
>>
>> Right.
>>
>>> Basically, the HTTP URI duality reality [1] isn't a part of the RDF
>>> spec.
>>
>> Right.
>>
>>> Thus, you cannot constructively conflate Linked Data and RDF.
>>
>> I didn't conflate them.
>
> You conflate them whenever you infer:
>
> 1. Linked Data is RDF

No, in the sentence "Linked Data is RDF" the word "is" means "is 
composed of" -- not "is the same as".  The word "is" has many 
definitions in English:
http://oxforddictionaries.com/definition/english/be

> 2. RDF is Linked Data.

I have never suggested that RDF is Linked Data.  I have pointed out more 
than once that Linked Data (in the established sense of the term) is 
*based* on RDF -- not the other way around.

>
> Linked Data is neither, it's something you can produce in very powerful
> form using RDF.
>
>> Linked Data (in the original and established sense of the term)
>> *builds* on RDF.  Not the other way around.  And the two are not
>> synonymous.
>>
>>> What you can do though, is talk about RDF based Linked Data.
>>
>> Yes, and in the original and established sense of the term "Linked
>> Data", *all* Linked Data is RDF based.
>
> It is not. Stop pushing that misconception.

I resent that accusation.  It is patently false, and I consider it 
libelous.

The vast majority of evidence shows that in the established sense of the 
term, Linked Data *is* based on RDF.

Please do not continue to make false claims either about the established 
meaning of the term "Linked Data" or about me.

Thank you,
David Booth

> RDF is not the progenitor of
> "Linked Data" in any shape or form. Computing precedes the World Wide
> Web, you know that.
>
>>
>>>
>>> To conclude:
>>>
>>> JSON-LD is a good effort at outlining how to produce RDF based Linked
>>> Data that's expressible and serializable using JSON.
>>
>> I agree that's what JSON-LD *should* be.
>
> Great!
>
>> But the problem is that that is *not* what the current draft of the
>> JSON-LD spec reflects.
>
> To the degree the current draft can be tweaked without inferring:
>
> 1. Linked Data is RDF
> 2. RDF is Linked Data.
>
> I won't have any issue, anything else, well I will be in total
> disagreement.
>
>> In the current draft, JSON-LD has no normative basis in the RDF model
>> or the RDF semantics **at all**.
>
> Fine, and does it really need to? The connection with RDF has to be
> through the algorithms for producing RDF from JSON-LD or vice versa.
>
>> Sure JSON-LD *can* be mapped to RDF, but that's not saying much,
>> because *any* language can be mapped to RDF.
>
> But that's saying all that needs to be said re. JSON-LD. The goals or
> JSON-LD are clearly spelled out.
>
>> The current draft reads as a completely parallel attempt at defining
>> an independent language for achieving similar goals as Linked Data (in
>> the original, established sense of the term), while redefining the
>> term "Linked Data" to include this parallel language.
>
> It is an option for JSON developers seeking to work with Linked Data.
> Developers who have next to no interest in RDF and its inability to shed
> its riddle-like image which makes comprehension eternally mercurial to
> this Web developer profile.
>
>>
>> If the definition of "Linked Data" were broadened beyond using RDF as
>> the information model, where would the line be drawn?
>
> Again, Linked Data and RDF are not the same thing. You can produce
> powerful and very useful Linked Data using RDF.
>
> You continue to assume that RDF invented the 3-tuple and entity
> relationship model. You assume that HTTP URIs are the only mechanism for
> de-reference and indirection baked into structured data representation etc..
>
> You can actually make 5-Star linked data using other URIs schemes. The
> downsides have more to do with the limitations in Web browsers and the
> ubiquity of this type of user agent re., the Web. On mobile platforms,
> the notion of URIs schemes works without the limitations imposed by
> desktop browsers etc..
>
>
>> Would Excel spreadsheets be considered "Linked Data" if they contained
>> HTTP URIs that resolved to other spreadsheets?
>
> What does a named cell in an excel spreadsheet actually do? It uses
> name-address indirection to give you a name that resolves to an address.
> The problem is that in this case the actual relation semantics are
> implicit and coarse at best. Thus, to some it could be considered Linked
> Data.
>
> Better example, what about a CSV file comprised of 3 cols that's used to
> express entity relations in 3-tuple form? Where cols 1 & 2 hold URIs and
> the 3rd col hold URIs or literals? Is that Linked Data?
>
>> Would relational database tables?
> No they are not.
>
>>  Would HTML documents?
>
> They are yet another example of coarse-grained linked data due to the
> fidelity entity relationship semantics. Remember, the HTML spec does
> have <link/> tags that denote relations.
>
>>
>> To step up a level: what is your goal in attempting to disassociate
>> RDF from Linked Data?
>
> Simple: end RDF narratives that are well intended but utterly
> distracting. RDF is useful without a distracting power-grab on "Linked
> Data" which is a very generic phrase. RDF based Linked Data is crystal
> clear and devoid of the aforementioned distractions.
>
> The real value of RDF is that it builds on the old entity relationship
> model by introducing explicit (rather than implicit) machine- and
> human-discernible entity relationship semantics. It also leverages the
> ingenuity of URIs as global identifiers for things in general.
>> What are you trying to achieve by redefining the term?
>
> I am  not redefining anything. RDF has never been defined as Linked
> Data. If that was the case the spec would specifically mandate the very
> behavior expressed in TimBL's meme.
>
>> Are you trying to invent a different Semantic Web that is JSON-based
>> instead of being RDF-based?
> If you assume that, then we are speaking past ourselves on an inter
> galactic level :-)
>
> Links:
>
> 1. http://twitpic.com/cmw52i -- illustrating hashless Linked Data URIs
> (Webb Super Keys) e.g. those used by DBpedia
> 2. http://twitpic.com/cmw72m -- illustrating hash based Linked Data URIs
> (Webb Super Keys)
> 3. http://bit.ly/T3kWUv -- Peter Chen's 1976 dissertation on the entity
> relationship model .
>
>
> Kingsley
>>
>> David
>>
>>>
>>>
>>> Links:
>>>
>>> 1. http://bit.ly/YxW21k -- HTTP URI Duality that lies at the core of
>>> Linked Data as espoused by TimBL's original meme.
>>>
>>> Kingsley
>
>
> --
>
> Regards,
>
> Kingsley Idehen	
> Founder & CEO
> OpenLink Software
> Company Web:http://www.openlinksw.com
> Personal Weblog:http://www.openlinksw.com/blog/~kidehen
> Twitter/Identi.ca handle: @kidehen
> Google+ Profile:https://plus.google.com/112399767740508618350/about
> LinkedIn Profile:http://www.linkedin.com/in/kidehen
>
>
>
>
Received on Monday, 29 April 2013 22:44:35 UTC

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