Re: Using URIs to identify non-information resources

Booth, David (HP Software - Boston) wrote:

>Given the thunderous silence I've heard in response to my
>thing-described-by.org proposal
>
I've been silent because I was still making up my mind :-)

I like the possibility to distinguish between a physical thing and an 
associated information  resource. 
A standard way to generate a URI for the former given the URI of the 
latter feels as a useful part, but still, only a part of complete 
solution that can be worked into a best practice guideline. Being able 
to specify the relation between the two URIs is another (again, the 
rdf:definedBy approach feels as only part of the solution).

Questions I was asking myself about your thing-described-by.org proposal 
include:
- If you want to change the URI of your homepage, do you also want to 
change the URI of yourself?  If not, the dereferencing gives you the 
"wrong" document. So what do you do?
- What if you use an HTML home page as the target URI in the 
thing-described-by.org (as you do now) and want to change that to an RDF 
file (e.g. at some point in the future you want to use your RDF/FOAF 
profile instead)?
- what if you want both the HTML and RDF option?
- what if you do not control the URI of the physical thing?
- etc...

Or more general: it feels a bit like the "wrong" way to do things: you 
define something "important"(the URI for yourself, a thing in the 
physical world) in terms of something "less important"  (some digital 
artifact or information resource that is likely to change, even if you 
would use things like purl.org etc)[1]. 

In connection to the multimedia task force: A similar problem occurs in 
multimedia annotation. Since the multimedia resource being described 
almost always represents something in the physical world, one wants to 
distinguish meta data about the multimedia resource (e.g. 
#rembrandtPainting dc:format 'image/jpeg') from meta data about the 
physical work (#rembrandtPainting dc:format 'oil on canvas').  Standards 
like the VRA Core 3.0 [2] address this by defining in the meta data 
record [3] whether the record is about the "work" itself or the "image", 
or digital artefact that represents the work.  Note that
- AFAIK, VRA is also not defining the relationship between a "work" 
record and its "image" records
- the painting itself may also represent things, so if your want to say 
something about the content of the painting, you might need another 
abstraction layer
- in the context of describing visual physical resources (e.g. 
paintings) a single work typically has multiple digital images that 
"represent" the work.  In general, it is often the other way around: a 
digital image may depict many things in the physical world (cf 
foaf:depicts vs foaf:img).
- rdfs:label is a common property for relating an abstract resource with 
a short literal text that can be used (for instance in a UI) to 
represent a resource, but we do not have a similar common property for 
non-textual media.  So if I want to tell my UI to show a thumbnail iso 
the literal given by rdfs:label, I need to define my own, non-standard 
property to do that. Idem for audio or video etc.

Comments welcome (and David, I'm sorry if this is a distraction from the 
discussion you want to provoke)

Jacco

[1] Could be me just being old fashioned: I just need to understand that all
     the real things around me are defined by their digital 
counterparts, but I'm not there yet :-)
[2] http://www.vraweb.org/vracore3.htm
[3] not sure how to translate the concept of a Dublin Core or VRA Core 
"record" to RDF... Reification might not be the best way to do it.  
Maybe named graphs are an option ...

Received on Monday, 25 July 2005 15:03:18 UTC