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Re: Semantics of rdfs:seeAlso (Was: Is it best practices to use a rdfs:seeAlso link to a potentially multimegabyte PDF?)

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Thu, 13 Jan 2011 13:04:24 -0500
Message-ID: <4D2F3EA8.9040600@openlinksw.com>
To: nathan@webr3.org
CC: Tim Berners-Lee <timbl@w3.org>, Martin Hepp <martin.hepp@ebusiness-unibw.org>, Linked Open Data <public-lod@w3.org>
On 1/13/11 12:04 PM, Nathan wrote:
> Hi Kinglsey,
>
> Kingsley Idehen wrote:
>> When our engine describes entities it can publish these descriptions 
>> using variety of structured data formats that include RDF. The same 
>> thing applies on the data consumption side. Basically, RDF formats 
>> are options re. Linked Data (the concept).
>
> A generic problem here, when using non RDF types with Linked Data over 
> HTTP, is that there's currently no way to indicate that a resource 
> is/has a set of machine readable "linked data" variants, in many cases 
> it is useful to publish and consume with linked data in CSV format and 
> related (as you well note) - but without prior out of band knowledge 
> that the representation contains, or is, linked data, the machines are 
> pretty much screwed. Typically the RDF variants don't have this 
> problem because the media type sets the expectation, so you can conneg 
> on an RDF type and know your getting back "linked data", you can't do 
> this with CSV and related with any expectation that you'll get back 
> "linked data" - thus, if there was some way to mark the set of 
> representations given upon dereferencing a URI as linked data, 
> containing rdf, rdfable 3 tuples, or a view thereof, it'd be a lot 
> friendlier to the web of data in general.

So what happens to RDFa in (X)HTML? Even worse, no DOCTYPE declarations?
What about various JSON dialects for Linked Data graphs?
How about N-Triples? Ditto TriX and others?

In my world view I see realities such as:

1. Spreadsheet and other desktop productivity users opening up a URL 
(directly or indirectly via WebDAV mounted to filesystem) -- this is a 
massive realm for Linked Data exploitation

2. Starting FYN (follow-your-nose) patterns in ODE, Sponger etc.. that 
might start from an RDF resource but eventually encounter resources that 
aren't RDF based.

Thus, I believe we have to consider:

1. Client side heuristics on the parts of Linked Data apps that deal 
with data format heterogeneity atop underlying S-P-O / E-A-V homogeneity 
re. propositions embedded in data.
>
> A typical approach would be to register new mediatypes, +variant 
> kinds, for instance text/rdf+csv or such like, but these types 
> wouldn't be well known throughout the internet, served correctly by 
> default in the likes of apache, or handed off to the correct consuming 
> programs by user agents - I'll leave it there, without a proposal, but 
> some indication to the machine would/will be needed to make this 
> approach friendlier for the web.

Remember a Linked Data Server can say (via HTTP): all I have is a CSV 
(or other non RDF format) based representation of the RDF (via 
mediatype) based Data you requested :-)

If you look closer, we are revisiting the issue of:  where does 
"resource" stop. Is it at the container or content level? In my world 
view, the content matters. Yes, mediatypes help, but ultimately we have 
to be much more open about the concept of Linked Data. Of course, a 
client (e.g. Tabulator) can say: I don't understand what you sent me 
etc..., which is fine, but it shouldn't be the basis for defining what 
Linked Data (the concept) is all about.

Again, I have no problems with RDF based Linked Data as a variation of 
the Linked Data concept. I just want clarity more than anything else. 
Being provincial about Linked Data (via RDF format specificity) isn't 
going to increase comprehension and adoption momentum.

>
> and as an aside: I do worry a little that there may be some 
> overloading of terms going on here, Linked Data (the concept) and 
> Linked Data (the protocol) - I'm unsure exactly how to define Linked 
> Data (the concept) but assuming you're referring to a broad range of 
> EAV variant 3-Tuple based data with URIs.

The concept of Linked Data is old. Linked Data at InterWeb scale 
courtesy of HTTP ubiquity is an immensely valuable (and mega cool!) 
contemporary spin on an old concept. What else can I say? I guess 
Google's your friend re. historic research on the subject: Linked Data  :-)

TimBL (as far as I know) has never claimed to have invented the concept 
of Linked Data. He dropped a note (subject: Linked Data) explaining how 
you can leverage AWWW as an effective mechanism for producing Linked 
Data at InterWeb scale.


Kingsley
>
> Best,
>
> Nathan
>
>


-- 

Regards,

Kingsley Idehen	
President&  CEO
OpenLink Software
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
Received on Thursday, 13 January 2011 18:04:55 UTC

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