Re: Explaining the benefits of http-range14 (was Re: [HTTP-range-14] Hyperthing: Semantic Web URI Validator (303, 301, 302, 307 and hash URIs) )

Dave, hello.

On 2011 Oct 20, at 22:31, Dave Reynolds wrote:

>>> Benefit 2: Conceptual cleanliness and hedging your bets
>>> 
>>> [...]Even if we can't spot the practical problems right now
>>> then differentiating between the galaxy itself and some piece of data
>>> about the galaxy could turn out to be important in practice.
>> 
>> It is.  I want to say that 'line 123 in this catalogue [an existing RDBMS] and line 456 in that one both refer to the same galaxy, but they give different values for its surface brightness'.  There's no way I can articulate that unless I'm explicitly clear about the difference between a billion suns and a database row.

[...]

> Perhaps benefit 2 could be reframed as being about forcing you to
> confront the map/territory distinction so you end up doing better
> modelling - whether or not you implement 303s.

I think that's _very_ true.  Perhaps one can say that any "information architect" should understand the IR/NIR distinction, however they subsequently decide to represent this.

> I think the discussion Leigh was trying to start was "can we more
> clearly article those benefits of the 'right way'". I was taking a shot
> a that, maybe a very limited off-target one.

While I think it's very important to be clear about precisely what one's URIs refer to, I'm starting to wonder if the benefits of the 'right way' (which is the IR/NIR and 200/303 distinction, right?) really are all that massive.

I think your listing of the costs and benefits <http://lists.w3.org/Archives/Public/public-lod/2011Oct/0158.html> is a useful summary.

> Most people I
> talk to grok the distinction, the hard bit is understanding why 303
> redirects is a sensible way of making it and caring about it enough to
> put those in place.

Yes: it's becoming clearer to me that this is what the discussion is really about, even though it started off being about the lament "why don't people understand this distinction?".

----

You also commented on ways to represent observational data.

> (1) Describe the observations explicitly using something like ISO O&M or
> the DataCube vocabulary:
> 
>   <http://catalogue1.com/observation123> a qb:Observation;
>       eg:galaxy      <http://iau.org/id/galaxy/m31>;
>       eg:brightness  6.5 ;
>       eg:obsdate     '2011-10-10'^^xsd:date ;
>       qb:dataset     <http://catalogue1.com/catalogue/2011> .
> 
>   <http://catalogue2.com/observation456> a qb:Observation;
>       eg:galaxy      <http://iau.org/id/galaxy/m31>;
>       eg:brightness  6.8 ;
>       eg:obsdate     '2011-09-01'^^xsd:date ;
>       qb:dataset     <http://catalogue2.com/catalogue/2011> .
> 
> (2) Each catalogue gives its own URI to its "understanding" of the
> galaxy so it can assert things directly about it without conflict:
> 
>   <http://catalogue1.com/galaxy/m31>  eg:brightness 6.5;
>      eg:correspondsTo    <http://iau.org/id/galaxy/m31> .
> 
>   <http://catalogue2.com/galaxy/m31>  eg:brightness 6.8;
>      eg:correspondsTo    <http://iau.org/id/galaxy/m31> .

For huge numbers of objects, the _only_ name they have is their number in some observational catalogue or other -- there's no canonical IAU name.  In a current project, we're setting up the support to be able to say 

    <http://catalogue1.com/galaxy/123> cat1:brightness xxx.
    <http://catalogue2.com/galaxy/456> cat2:brightness yyy.
    <http://catalogue1.com/galaxy/123> owl:sameAs <http://catalogue2/galaxy/456>.

We probably also want to reify the database rows where the first two statements come from, in order to make last-modified-like statements about them, but whether we do that with a named graph, or some other way, is a problem we haven't had to confront quite yet.

> In *none* of those cases doesn't it make any difference whether when I
> dereference <http://iau.org/id/galaxy/m31> in a browser I get a web page
> saying "I denote the galaxy M31" or I get a 303 redirect to something
> like <http://iau.org/doc/galaxy/m31> which in turn connegs to a web page
> saying "The URI you started with denoted the galaxy M31, me I'm just a
> web page, you can tell me by the way I walk".

Well, I think it does matter, because in this case, the thing named <http://catalogue1.com/galaxy/123> could plausibly be either the galaxy or the database row (and I suppose I could claim the latter as a NIR, with a following wind), and I'd need to be able to state, somewhere, which it is.  But that's handled by my providing some RDF somewhere which explains which it is: the problem is how to get to that RDF without drawing some ambiguous or wrong conclusions on the way.

Best wishes,

Norman


-- 
Norman Gray  :  http://nxg.me.uk
SUPA School of Physics and Astronomy, University of Glasgow, UK

Received on Friday, 21 October 2011 14:36:15 UTC