W3C home > Mailing lists > Public > semantic-web@w3.org > May 2013

Re: non opaque primary topics

From: Henry Story <henry.story@bblfish.net>
Date: Thu, 9 May 2013 09:30:43 +0200
Cc: Tim Berners-Lee <timbl@w3.org>, Melvin Carvalho <melvincarvalho@gmail.com>, Semantic Web <semantic-web@w3.org>
Message-Id: <E3EDBBF8-91B9-45A2-884C-5EE5C87D1276@bblfish.net>
To: Sampo Syreeni <decoy@iki.fi>

On 9 May 2013, at 04:04, Sampo Syreeni <decoy@iki.fi> wrote:

> On 2013-05-08, Tim Berners-Lee wrote:
> 
>> The point about this is that all kinds of languages can talk about the same thing in different ways. To get interopabiliity, though, you have to stick to a limited set of local identifiers which will work in any language.
> 
> Why use local identifiers at all?
> 
> The semweb works on the assumption that whatever URI is being talked about is globally unique. It doesn't say how you make it unique, but that's the basic invariant it expects.
> 
> What is being done here is that a) structure is being ascribed to a particularly common form of URI, and that structure is being taken advantage of, instead of the reference remaining an opaque (surrogate) key (in my own relational parlance). Then, b) once you have that structure, people are being asked to agree upon the particulars of that format, and to utilize it. Finally, c) it is being suggested that this should become a standard which lets you deduce programmatically and locally from a person's URI where to find hir "stuff". Essentially to derive some sort of URL from the corresponding URI.
> 
> I find this idea highly doubtful, and as long as I've known about RDF and the various forms of URIs, I've battled against them. Given that I happened to have access to a globally unique, guaranteed, naming hierarchy, I sidestepped the process from the start and went with calling myself by a legitimate URN, under the ISO OID tree. I've formally been called <urn:oid:1.3.6.1.4.1.12798.1.2049.1.497> within the semweb for some time now. You never need to worry about the XML syntax that way, including the qname hassle.

And if I wanted to find out the sense of <urn:oid:1.3.6.1.4.1.12798.1.2049.1.497> I'd have no way of knowing, not without say crawling the whole
web and then doing something like statistical analysis on how the term is used in the documents I got access to. That is why building a linked data web with urn's is hopeless.

For more on the sense/reference distinction see the WebID spec:
https://dvcs.w3.org/hg/WebID/raw-file/tip/spec/identity-respec.html#overview


> 
> I think everybody who wants to name themself ought to do the same: latch onto some guaranteed to be unique branch of the full URI hierarchy and stick with their choice, or if they don't happen to have access to such a naming hierarchy even at the leaf level, then go with a randomly generated one within it (the random version of UUID will do the job) or perhaps a tag URI (Internet Law as of RFC 4151).
> 
> Then use some other, independent mechanism to show where your data is. Plain and simple, separate form from functionality. Maybe the mechanism could be just the :seeAlso one I used when I put up my files "ages ago". Maybe use so other, whipped-up predicate like "canonicalSource" and deal with the temporal implications elsewhere. Maybe do both, and if you're worried about security, sign your stuff.
> 
> But whatever you do, don't inpute structure into your URI's, or overload locators and identifiers. That's just bad practice, at least from my own relational DB perspective, not to mention the work of the IETF in finally generalizing URLs into URIs.
> 
> Not to mention that you'd cut me out of semweb if you did that, since I *am* an URN. :)

A URN is a string, and you are an agent of some type :-)

> 
>> Ooops! facebook's empty localid isn't allowed as a localid.
> 
> Those can be dealt with via :sameAs or some like mechanism. Sure, use these funky names as much as you like, but don't make it into a standard that they are expected, or that they should have any particular format which can be utilized. (Or if you do, at the very least make it sure that they work with the kind of architecture I was talking about above, too.)
> -- 
> Sampo Syreeni, aka decoy - decoy@iki.fi, http://decoy.iki.fi/front
> +358-50-5756111, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
> 

Social Web Architect
http://bblfish.net/
Received on Thursday, 9 May 2013 07:31:55 UTC

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