Re: ISSUE-66: LinkedData™

Hi all,

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.)

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].
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.
I'd dare to say that the majority of people do assume
that Linked Data is just done with RDF.
So to what extent is it then necessary to clarify this?

In that context, Dan Brickley sent a useful comment to me:
“RDF is to Linked Data as HTML is to the classic Web, maybe”.

>> i was specifically trying not to get that discussion going. just asking 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.

What do you think about the current introduction
to the triple pattern fragments spec [1]?
Not knowing about this issue yet, I phrased it as:

    By publishing Linked Data [LINKED-DATA],
    we enable automated clients to consume information.
    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?

> 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.

And personally, I wonder to what extent SPARQL is part of Linked Data;
and does that mean the query language, the protocol, or both?


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.

For triple pattern fragments, by definition, we are limited to the RDF triple model.
That does not mean that other kinds of fragments would have such a strong dependency;
so other fragment types we define might be independent of RDF.

Best,

Ruben

[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

Received on Tuesday, 5 August 2014 09:08:13 UTC