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Re: Graphs and Being and Time

From: David Wood <david.wood@talis.com>
Date: Tue, 1 Mar 2011 13:52:19 -0500
Message-Id: <4C52EF8D-3D44-4DEC-ACFC-FF87F74C0505@talis.com>
To: RDF WG <public-rdf-wg@w3.org>

On Mar 1, 2011, at 05:32, Nathan wrote:

> Hi David,
> 
> Sorry, I've realised the below is wrong, so corrected:
> 
> Nathan wrote:
>> David Wood wrote:
>>> On Feb 24, 2011, at 13:12, Pat Hayes wrote:
>>> 
>>>> It is much simpler: it is just wanting the WG to acknowledge that "an RDF graph" can either be a mathematical set, or it can be some kind of document or data structure or file than can be transmitted over a computer network. But it can't be both.
>>> 
>>> What is the difference between an "RDF graph" and a RESTful "resource"?  What is the difference between an "RDF graph token" and a RESTful "representation"?
>> REST maps a resource to a set of values over time, each single value has a 1:N relationship with representations, "RDF Graph" (the mathematical set, platonic abstraction, g-snap) equates to a single value, and "RDF Graph Token" equates to a representation of that single value.
> 
> REST maps a resource to a set of values over time, each single value is a representation, representation equates to "RDF Graph Token" (a chunk of rdf/xml or turtle, a g-text in Sandro's mail).
> 
> The g-snap, or abstract graph, isn't a concept which relates to any REST concept, rather it is something specific to our RDF use-cases, in that we have a platonic abstraction, a mathematical set of triples, which we juggle different realizations of (from in memory structures through to serializations and so forth).
> 
> So, to re-answer your question, "RDF Graph" is a term we've used to refer to both the abstract set of triples, and the realizations of. The only thing which equates anywhere near a "RESTful resource" in our communities are "Named Graphs" and of course linked data which uses RESTful resources, we GET <u> to retrieve a realization of an abstract set of triples, to get some RDF in some format.
> 


Pardon me for saying so, but that doesn't make sense to me.

A RESTful resource may be anything:  "the intended *conceptual* target of a hypertext reference" was one way Roy Fielding put it (emphasis mine).  There is no reason I can see that an abstract, mathematical concept cannot be a RESTful resource.

Andy neatly ducked the question of mapping to a resource:

On Mar 1, 2011, at 06:30, Andy Seaborne wrote:
> g-box - place holding a sequence-over-time of values
> g-snap - one such value
> g-text - the REST representation.


Instead, I suggest something like this:

g-box - a REST resource, over time.
g-snap - a conception of the REST resource at the time it is addressed.
g-text - the REST representation.

That seems to address Pat's concern and stays very Webby.

Regards,
Dave



> Apologies, just had to correct myself there.
> 
> Best,
> 
> Nathan
Received on Tuesday, 1 March 2011 18:56:22 UTC

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