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Re: Using MIME types in RDF/DAML and Image Metadata

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Sun, 30 Mar 2003 23:51:42 +0100
To: Yarden Katz <katz@underlevel.net>
Cc: www-rdf-interest@w3.org, www-rdf-logic@w3.org
Message-ID: <5689.1049064702@hoth.ilrt.bris.ac.uk>

>>>Yarden Katz said:

[Aside, this message probably didn't need cross posting ]

> Hi,
> 
>   What are some approaches to assign MIME-types to certain RDF or DAML
>   resources?  For example, consider the following:
> 
>     <daml:ObjectProperty rdf:ID="Picture">
>       <rdfs:label>A Picture</rdfs:label>
>       <rdfs:comment>A cute picture class in DAML</rdfs:comment>
>       <rdfs:domain rdf:resource="#SomeObject"/>
>       <rdfs:range rdf:resource="#????"/>
>     </daml:ObjectProperty>

I'm not familiar with the semantics of daml:ObjectProperty (or the
OWL equivalent), however ...

>   An agent attempting to render RDF data has no way of knowing that
>   resources linked to using the above property are images and are to
>   be handled as such.  How can these meaning be conveyed in RDF?  The
>   obvious method seems to be to assign a MIME type such as
>   "image/jpeg" as the range of this property, but I do not know how
>   that can be expressed.  Googling showed up a seemingly relevant link
>   "Mapping Between Content-Types (MIME types) and URIs" from
>   <http://rdfig.xmlhack.com/2001/05/09/2001-05-09.html> but it is
>   broken.  Any ideas you may have on how to attach this elementary
>   problem would be great, whether involving usage of MIME or not.

A quick google finds:

  Mapping between URIs and Internet Media Types
  TAG Finding 8 April 2002 (Revised 27 May 2002)

  http://www.w3.org/2001/tag/2002/01-uriMediaType-9

which is probably the best current description and set of ideas on
this problem.

The other way uses familiar and well deployed Dublin Core vocabulary
an it's dc:format property.  It takes as primary recommend value the
IMT / MIME Type as a literal.  You might be able to do some inference
magic to imply that all your 'Picture's have the dc:format
"image/jpeg".  Otherwise you'd need to put it in the instance data.

See http://dublincore.org/documents/1999/07/02/dces/
and many DC and RDF apps use this already.

> 
>   I have a second question that's related to the above: is there some
>   uniform way to note coordinates on an image (similar to an image
>   map) in RDF?  For example, expressing something a long the lines of
>   "Instances of Object X should be placed in coordinate (X, Y)"  The
>   most relevant link I found was:
>   <http://www.w3.org/2001/08/rdfweb/foafwho/imagemap/> but it does not
>   show an RDF representation of an image map, only the plain HTML one.

Sorry, I've no info on this question.

Dave
Received on Sunday, 30 March 2003 17:54:23 GMT

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