Re: ISSUE-66: LinkedDataT

On 08/05/2014 07:44 AM, Markus Lanthaler wrote:
> On 5 Aug 2014 at 11:07, Ruben Verborgh wrote:
>> Jumping in, as this is very relevant for the Linked Data Fragments spec
> [1].
>> In fact, this issue appearing after I drafted an introductory section
> called
>>      "What Linked Data is"
>> might not be a coincidence. (And it's very good timing in any case.)
>
> Yeah, this is mostly about the Linked Data Fragments spec.
>
>
>> Let me start out by saying I was totally oblivious of "non-RDF Linked
> Data".
>> I.e., I had always assumed that Linked Data is in RDF;
>> probably because Tim's original principles explicitly mention this [2].
>
> Funny fact: the "original principles" didn't explicitly mention it:
>
> https://web.archive.org/web/20061115043657/http://www.w3.org/DesignIssues/Li
> nkedData.html

That's because everyone discussing it at the time knew very well the 
context.  The semantic web community was suffering from use of the 
existing term "semantic web", both because it is misleading -- 
"semantics" is strongly associated with natural language processing 
(NLP), but the semantic web has nothing to do with NLP -- and because it 
sounds overly imposing/pedantic.  There was also concern that some users 
of RDF were not making use of the *linking* capability of URIs in their 
RDF (i.e., not making URIs dereferenceable).  TimBL coined the term 
"linked data" as a more accurate and marketable term for the original 
concept of the semantic web, which is based on RDF.

David

>
> It took 3 years till that was added.
>
>
>> Then again, we all know the principles are quite vague:
>> - RDF* and SPARQL are mentioned between parentheses.
>>    Did this mean "e.g., RDF*, SPARQL", or "i.e., RDF*, SPARQL"?
>>    That's an important difference, and we'll likely never know.
>> - Where is the asterisk after RDF ever resolved?
>> Maybe I just missed the majority of the discussion;
>> i.e., posts like [3] were written in 2009.
>>
>> That said, me being in the community for 4 years
>> and never having heard about (or being selectively deaf towards)
>> non-RDF Linked Data, means something at least.
>
> We had a very long (and heated) discussion about this when we standardized
> JSON-LD. It starts more or less here
>
>
> http://lists.w3.org/Archives/Public/public-rdf-comments/2013Jun/thread.html#
> msg28
>
> in case you want to waste a couple of hours (days?) reading more about this
> :-)
>
>
>> I'd dare to say that the majority of people do assume
>> that Linked Data is just done with RDF.
>
> That's obviously true for the Semantic Web community. Not so true for the
> rest of the world :-) Hydra tries to bridge the gap between those two worlds
> (just as JSON-LD does).
>
>
>> So to what extent is it then necessary to clarify this?
>
> I think it is very important as our group is not a homogenous group of
> Semantic Web experts.
>
>
>>>> i was specifically trying not to get that discussion going. just asking
>
> I'd also like to urge to not get into that discussion.
>
>
>>>> whether there should be some definition/clarification of the term, just
>>>> to let readers know what it means in the context of the spec/community.
>>>> if you define a broad term to mean a narrow thing, then this might be
>>>> helpful to avoid possible confusion.
>
> In my opinion we should define it. At the moment, I think it is clear that
> LDF are *exclusively* for RDF. It would be interesting to see if it can be
> generalize in the future but till we get to that point I think we should
> simply be honest about it.
>
>
>> What do you think about the current introduction
>> to the triple pattern fragments spec [1]?
>
> It's quite nice but I think it could be further improved, especially for
> people without a lot of SemWeb background.
>
>
>> Not knowing about this issue yet, I phrased it as:
>>
>>      By publishing Linked Data [LINKED-DATA],
>>      we enable automated clients to consume information.
>
> Hmm... automated clients such as Google are quite happy consuming plain old
> HTML... I know what you are trying to say but people who haven't spent a
> whole lot of time on this won't understand it, I think.
>
>
>>      In practice, this information is available as RDF triples [.]
>>
>> So it leaves the question open whether non-RDF Linked Data exists;
>> it just says that, in practice, it will be RDF. Good enough?
>
> Maybe it would be more straightforward to explain it the other way round:
>    - documents are in natural language
>    - machines are bad in understanding natural language
>    - machines prefer structured data using unambiguous identifiers
>    - the Web uses URLs* as identifiers
>    - RDF allows data to be expressed in a machine-processable way by
> leveraging URLs
>    (- RDF expresses data in the form of triples) -- could be omitted
>    - RDF can be serialized in various formats such as JSON-LD, HTML+RDFa, or
> Turtle
>
> * I think simply talking about URLs instead of URI or IRI is fine in this
> case
>
> I would also suggest to use a different term than "Linked Data document". Is
> it actually needed or could we also get rid of this concept?
>
>
>>> I think a definition could help.  I suggest copying the one from the
>>> W3C Linked Data Glossary verbatim (and referencing that document),
>>> rather than trying to craft a new one and risking another long debate
> about
>>> what it should be.
>>
>> Sadly, I think that definition is quite complicated.
>> Here it is at full length, copied from [4]:
>>
>>      Linked Data
>>
>>      A pattern for hyperlinking machine-readable data sets to each other
>>      using Semantic Web techniques, especially via the use of RDF and URIs.
>>      Enables distributed SPARQL queries of the data sets and a browsing
>>      or discovery approach to finding information (as compared to a search
> strategy).
>>      Linked Data is intended for access by both humans and machines.
>>      Linked Data uses the RDF family of standards for data interchange
>>      (e.g., RDF/XML, RDFa, Turtle) and query (SPARQL).
>>      If Linked Data is published on the public Web,
>>      it is generally called Linked Open Data. See also [Linked Data
> Principles].
>>
>> It forces you to understand:
>> - Semantic Web
>> - RDF
>> - URIs
>> - SPARQL
>> to make sense out of it.
>
> I fully agree. This definition is not going to help anyone.
>
>
>> On the technical level, nothing prohibits us from making Linked Data
>> Fragments broader than RDF. We'd have to be very careful, however,
>> that the concept would still be sufficiently meaningful; that it
>> doesn't become hollow by broadening it.
>
> Yeah, I would like to explore that in the future. However, till we get
> there, we should make it clear that at least a mapping to RDF is required.
>
>
> Cheers,
> Markus
>
>
>> [1] http://www.hydra-cg.com/spec/latest/linked-data-fragments/
>> [2] http://www.w3.org/DesignIssues/LinkedData.html
>> [3] http://cloudofdata.com/2009/07/does-linked-data-need-rdf/
>> [4] http://www.w3.org/TR/ld-glossary/#linked-data
>
>
> --
> Markus Lanthaler
> @markuslanthaler
>
>
>
>
>
>
>

Received on Tuesday, 5 August 2014 18:03:39 UTC