Re: Proof: Linked Data does not require RDF

On 6/18/13 12:44 AM, David Booth wrote:
> On 06/17/2013 08:11 PM, Manu Sporny wrote:
>> On 06/17/2013 06:21 PM, Luca Matteis wrote:
>>> This still doesn't answer my initial question "How do you produce
>>> Linked Data without RDF?".
>>
>> Here's the first way (plain 'ol JSON object):
>>
>> {
>>    "id": "http://example.com/people/luca",
>>    "type": "http://schema.org/Person",
>>    "name": "Luca Matteis"
>> }
>>
>> The document above is interpreted as Linked Data using the following 
>> rules:
>>
>> 1. The thing you're talking about is identified via 'id'.
>> 2. The type of the thing you're talking about is identified via 'type'.
>> 3. All keys, except for 'id' and 'type', are appended to 'type''s value,
>>     with a '/' separator.
>>
>> That's Linked Data. It has no formal relationship to RDF.
>
> No, it is data that is linked.

That is simply inaccurate.

The data structure is web-like i.e., the actual data representation is 
like a web. Basically, you have an entity relationship comprised of: 
Entity, Entity Attribute, and Entity Attribute Value.

Note, the Attribute's role in the relationship is to map the Entity to a 
Value. It also facilitates the association between the Entity denoted by 
an Identifier and a Value also denoted by an Identifier. In addition to 
all of this, it also serves the role of a Predicate when dealing with 
sets of relationships (i.e., Relations) i.e., the truth value tester for 
Relation membership.

You denote the Entity, Attribute, and Value parts of a relationship 
using identifiers (these may be literals or references).

> I would not consider it Linked Data (the term of art) because there is 
> no standards-based way to interpret it as RDF.

"term or art" how is that relevant to this technical discussion?

> You are using private knowledge to interpret its meaning.

Put differently, the entity relationship semantics aren't explicit. You 
don't need "term of art" as an ambiguity vector in this debate.

> Bear in mind a document does not have to *look* (overtly) like RDF to 
> *be* RDF -- i.e., to be standards-based interpretable as RDF.

I already provided an example of document [2] bearing content that looks 
like RDF but isn't explicitly RDF while being 100% Linked Data i.e., it 
complies with the principles outlined in any of TimBL's meme relating to 
Linked Data.

> Arbitrary XML documents that use GRDDL are a good example.  If there 
> were a standards-based equivalent of GRDDL for the above plain old 
> JSON, then IMO it *would* qualify as Linked Data (assuming the URIs 
> are dereferenceable to more Linked Data) *because* it could be 
> interpreted via standards as RDF.
>

You are getting closer to the core distinguishing characteristics that 
RDF adds to Linked Data. Unfortunately, you also keep on pivoting back 
to an ambiguity zone that is indefensible. Look, RDF simply enables the 
addition of *explicit* entity relationship semantics to this matter of 
web-like structured data representation. If the entity relationship 
semantics are comprehensible to humans and machines, they are deemed 
interpretable by either. Basically, we are back to the fact that RDF 
makes it possible to reason on the web-like structured data.

RDF cannot make a flawed play for the entire subject of structured data 
representation that leverages references as entity identifiers (or 
denotation/naming mechanisms). That will never be accepted by anyone 
with a modicum of knowledge about structured data representation. As I 
asked some time ago, is RDF based on anything at all? Is this the one 
unique technology devoid of genealogy?

>>
>> Here's the second way (Microdata):
>>
>> http://www.w3.org/TR/microdata/
>>
>> The base Microdata spec has nothing to do with RDF. However, if you are
>> going to assert that RDFa is Linked Data, then you have to assert that
>> Microdata is Linked Data. Since Microdata has no linkage to RDF, what
>> are you left with? Answer: A syntax that allows you to express Linked
>> Data without using RDF in any way.
>
> I don't know the status of that spec, but if there is a 
> standards-based way to interpret it as RDF, then it qualifies as 
> Linked Data.

We are not discussing a W3C spec at this point. I also don't assume that 
by the W3C hosting this mailing list one has to instinctively assume 
that all conversations are about W3C specs. Thus, with the context 
clarity in place, how can you not see that Microdata is just another 
syntax for creating web-like structured data that's 100% compatible with 
the principles outlined in TimBL's original meme?

> If not, it doesn't.

At this point in the thread, you shouldn't be spooked when I assert that 
you are now conflating RDF and Linked Data. You are inserting a defining 
characteristic of Linked Data into you basis for determining what 
constitutes Linked Data. You are using the word "interpret" and earlier 
on you made reference to location of knowledge required for the 
interpretation in question.

When TimBL added "..use the standards (RDF, SPARQL)..." to his revised 
meme it had nothing to do with being able to interpret entity 
relationship semantics.

> It is as simple as that.  (Well, assuming it also makes URIs 
> dereferenceable to other Linked Data, etc.)
Inaccurate.


URIs that resolve in a manner that delivers Name->Address indirection 
such that a URI resolves to the description of its referent is the crux 
of the matter re. Linked Data (or web-like structured data). This 
pattern is fundamental to the Web as a whole, it just so happened that 
we applied it to entities of type "HTML Document" and other digital 
resources -- long before there was any notion of a Resource Description 
Framework and its ability to make Blogic (logic enhanced web-like 
structured data that scales to the World Wide Web).

>
>>
>> Here's the third way (RFC-5988: Web Linking):
>>
>> http://tools.ietf.org/html/rfc5988
>>
>> The Web Linking RFC defines a typed connection between two resources
>> that are identified by Internationalised Resource Identifiers (IRIs) and
>> is comprised of:
>>
>>     o  A context IRI,
>>     o  a link relation type (Section 4),
>>     o  a target IRI, and
>>     o  optionally, target attributes.
>>
>> Isn't this Linked Data as well?
>
> If it expresses an RDF triple (and if the URIs are dereferenceable to 
> more Linked Data), then yes.  Does it?  I'm not sure.  In section 3 I 
> see:
> [[
>    A link can be viewed as a statement of the form "{context IRI} has a
>    {relation type} resource at {target IRI}, which has {target
>    attributes}".
> ]]
> So although that looks somewhat RDF-ish, it is not clear exactly what 
> RDF it should represent.  So it looks to me like it is data that is 
> linked, but not Linked Data.

That's once again inaccurate. You are conflating the unique 
characteristics of RDF and Linked Data.

>
>>
>> Here's a fourth way (HAL - Hypertext Application Language):
>>
>> http://stateless.co/hal_specification.html
>>
>> """
>> HAL provides a set of conventions for expressing hyperlinks to, and
>> embeddedness of, related resources - the rest of a HAL document is just
>> plain old JSON or XML. Instead of using linkless JSON/XML, or spending
>> time developing a custom media type, you can just use HAL and focus on
>> defining and documenting the link relations that direct your clients
>> through your API. HAL is a bit like HTML for machines, in that it is
>> generic and designed to drive many different types of application.
>> """
>>
>> HAL is also Linked Data.
>>
>> To assert that Linked Data requires RDF requires you to make compelling
>> arguments against at least these four pieces of evidence.
>
> They are all data that is linked, but I (and apparently most others in 
> the Semantic Web context) would not consider them Linked Data, because 
> IMO Linked Data should support the goal of the Semantic Web, and as I 
> explained at
> http://lists.w3.org/Archives/Public/semantic-web/2013Jun/0120.html
> that requires RDF, because RDF is the chosen standard universal 
> information model for the Semantic Web.

When you have web-like structured data (crafted with HTTP URIs) combined 
with explicit entity relationship semantics delivered by RDF, you end up 
with a higher-fidelity Semantic Web.

In its most basic form, the World Wide Web has been a coarse-grained  
Semantic Web since inception! What do I mean by the Web has been a 
Semantic Web since inception? I mean its been a Web of entity 
relationships woven together by HTTP URIs. In the most basic sense, 
every Web Resource is related to other Web Resource i.e., one Web 
Resource is in a "LinksTo" relation with others. Thus, it's the  
"LinkTo" relation that underlies the Web, everything else is about 
semantics that provide granularity to the aforementioned "LinksTo" 
relation.

We are all related, that's a fact. How? That's a different matter since 
we are all related is different ways i.e., we are all members of 
different relations.


Links:

1. 
http://kingsley.idehen.net/DAV/home/kidehen/Public/DropBox/Public/Linked%20Data%20Resources/linked-data-rdf-test2.ttl 
-- running example of a document comprised of Linked Data content that 
isn't indistinguishably RDF (i.e., it's 100% compliant with TimBL's 
memes while not being uniquely RDF)

2. http://bit.ly/13lcdAM -- Vapor (Linked Data principles verification 
utility) report for DBpedia's URI that denotes the Linked Data concept

3. http://dbpedia.org/page/Linked_data -- URI/URL that denotes an HTML 
document that describes the Linked Data concept (note: the foot section 
also re. alternative representations of the same entity description)

4. 
http://dbpedia.org/describe/?uri=http://dbpedia.org/resource/Linked_data 
-- URI/URL that denotes an alternative HTML based document that 
describes the Linked Data concept from DBpedia (note: the footer section).


>
> David
>
>
>
>
>


-- 

Regards,

Kingsley Idehen	
Founder & CEO
OpenLink Software
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