W3C home > Mailing lists > Public > public-rdf-wg@w3.org > October 2011

Re: Graph labels vs. graph names. (was: Re: complete graphs)

From: Steve Harris <steve.harris@garlik.com>
Date: Wed, 5 Oct 2011 15:54:55 +0100
Cc: RDF Working Group WG <public-rdf-wg@w3.org>
Message-Id: <D2254802-2097-4294-ABF6-E6C5842C18E5@garlik.com>
To: Sandro Hawke <sandro@w3.org>
On 5 Oct 2011, at 14:21, Sandro Hawke wrote:

> On Wed, 2011-10-05 at 13:22 +0100, Richard Cyganiak wrote:
>> 
>> Implementers and users of SPARQL seem to be generally perfectly ok
>> with relying on private conventions. 
> 
> What sort of private conventions have you seen?    I've heard people
> talk about:
> 
>  1. graph tag is the URL they once fetched the graph from
>  2. graph tag is the URL on which they publish the graph
>  3. graph tag is some sort of non-dereferenceable genid
>  4. graph tag is primary subject URI of the graph (eg the person, for
> FOAF)

In Garlik we use all of these, and also use "graph tag is the URI we derived data from, appended with the ISO date as a fragment identifier " when mining data from web pages, PDF docs etc.

e.g. <http://plugin.org.uk/#2011-10-05>

This allows us to track changes over time, which would otherwise be difficult.

> It seems to me the variation here is an impediment to interoperability.
> If my code talks to a new sparql server, and doesn't know which of these
> conventions is being used, how can it do its job?   (Feel free to
> replace "talks to a new sparql server" with "fetches a TriG document",
> etc.)

I don't understand the rationale for wanting to normalise behaviour here. We don't mandate a particular structure for subject URIs, for example. In FOAF files I can use any URI I feel like to describe people, e.g. <#me>, <#i>, <http://alice.example/>. Doesn't seem to cause any significant interoperability problems.

- Steve

> I suggest we settle on a sort of merge of 2 and 3, which can in some
> circumstances be stretched to include 1.    When we talked about this
> some months ago, someone advocated 4, then agreed 2 was fine for their
> purposes and probably better anyway.
> 
>      -- Sandro
> 
> 
> 
Received on Wednesday, 5 October 2011 14:55:25 GMT

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