- From: Kingsley Idehen <kidehen@openlinksw.com>
- Date: Fri, 14 Jun 2013 07:23:28 -0400
- To: "public-lod@w3.org" <public-lod@w3.org>
- Message-ID: <51BAFD30.3050301@openlinksw.com>
FYI: I am cc'ing this list because the it provides a very good analysis of the current problem re. Linked Data and RDF conflation. I encourage you to read on.... On 6/14/13 3:30 AM, Gregg Reynolds wrote: > A couple more things regarding LD and RDF: > > On Thu, Jun 13, 2013 at 10:16 AM, Gregg Reynolds <dev@mobileink.com> wrote: > > >> The third of the four "properties" listed in the intro (which draws on TBL's note) is "the name IRIs, when dereferenced, provide more information about the thing". > This doesn't really work, just because it adds "about the thing". > TBL's original text reads: > > "When someone looks up a URI, provide useful information,..." > > Adding "about the thing" [i.e. named by the URI] botches it. Consider > "http://.../Napoleon.html". I would expect that URI, when > dereferenced, to provided information about Napoleon, not about the > HTML page itself. In other words, that URI denotes an HTML page; > dereferencing it according to the JSON-LD introduction (quoted above) > ought therefore to provide information about that HTML page, not about > Napoleon. That obviously doesn't work, since it would mean that the > things named by IRIs should only be about themselves. > > But TBL's original text also - "provide useful information" - is not > very enlightening. "Always wear clean underwear" is useful > information but it would be strange indeed if all URI lookups yielded > that advice. And besides, what else does anybody expect - non-useful > information? > > What I think TBL's item 3 really means is just: when somebody looks up > your URI, do not ignore the request and try not to return a 404 or > other error code. Which is coming pretty close to vacuous, for my > money. > > The original Item 4 isn't much better: "Include links to other > URIs..". What's a "link to another URI"? The intro of JSON-LD is a > slight improvement: "4) the data expresses links to data on other Web > sites." But what's that supposed to mean? Any other website? The > W3C site? Can we change this to "my website"? What do "web sites" > have to do with it anyway - I thought this was about data. > > Here's my take on LD: > > 1. use IRIs as names of stuff (rather than as URLs, i.e. addresses, > i.e. names of locations); > 2. exploit DNS by using HTTP URIs so that they will be (potentially) > resolvable; in effect this allows your IRI names to be treated as URLs > for the purpose of dereferencing; > 3. configure your servers so that requests for the URIs under your > control are not ignored and do not return errors; > 4. finally, the response you make to requests should include HTTP > URIs as appropriate leading to additional relevant and useful data. > > Now that's a pretty clear description of a set of practices. It still > fudges critical things like what counts as relevant and useful data, > but that's ok, it's a minimal defnition. Whether this is called > "Linked Data" or not is irrelevant. So just to avoid pointless > debates about the One True Meaning of LD lets call this "HTTP-Data > Publication Practices" (HDPP). The essential criteria of demarcation > are just use of HTTP URIs and returning useful and relevant > information possibly including further links. > > Note that the Plain Old Hypertext Web - let's call it the web of HTML > data - fits this description, since HTML webpages are data. So the > four practices are not sufficient to demarcate HTTP-Data (i.e. LD) > from HTML-Data. > > Now the question is: how is this related to RDF and JSON-LD? > > The most obvious difference is that HDPP as stated does not depend on > the use of formal, explicitly expressed claims (statements) of any > kind, let alone RDF triples. The same is true of TBL's LD practices > note. > > JSON-LD, like RDF, does involve the expression of claims in this > sense, even if it does not say so explicitly: it's built-in. But its > definition of LD in the intro muddies things since it includes an > unworkable stipulation that what a URI names should be about the URI. > Furthermore, insofar as JSON-LD claims to be a kind of LD language, > while sticking to a definition of LD that does not include explicit > claims, and at the same time deploys an explicit claim language while > more-or-less pretending it doesn't (i.e. disingenuously), it is > inconsistent. > > The conclusion I draw is that JSON-LD obviously does deploy explicit > claims (in the form of covert triples). But it does not follow that > we are compelled to say that it deploys (or uses, is based on, etc.) > RDF. In other words, I don't see a warrant for the implicit claim > that RDF is synonymous with support for expression of explicit claims. > So I don't see a problem with not smearing "RDF" all over the spec, > but I do see a relatively big problem with trying to hide the fact > that JSON-LD is for expressing claims explicitly using the same > (conceptual) device RDF uses, and for denying that it is in fact an > extension of plain old LD (or HTTP-Data). So I will probably think of > it (and explain it) as an LD language extended by explicit claims > using a (covert) topic-comment regime, which allows it to directly > express RDF graphs. > > Cheers, > > Gregg > > -- Regards, Kingsley Idehen Founder & CEO OpenLink Software Company Web: http://www.openlinksw.com Personal Weblog: http://www.openlinksw.com/blog/~kidehen Twitter/Identi.ca handle: @kidehen Google+ Profile: https://plus.google.com/112399767740508618350/about LinkedIn Profile: http://www.linkedin.com/in/kidehen
Attachments
- application/pkcs7-signature attachment: S/MIME Cryptographic Signature
Received on Friday, 14 June 2013 11:23:29 UTC