W3C home > Mailing lists > Public > www-rdf-interest@w3.org > November 1999

Mime types, Literals == Resources

From: Jonas Liljegren <jonas@paranormal.o.se>
Date: Sat, 20 Nov 1999 02:28:16 +0100
Message-ID: <3835F930.63773D52@paranormal.o.se>
To: Pierre-Antoine CHAMPIN <champin@cpe.fr>, RDF Intrest Group <www-rdf-interest@w3.org>
Pierre-Antoine CHAMPIN wrote:
> 
> I think this raises a question about the semantic relation between Literal and Resources.

It would be nice to let the literal BE the resource content. The XML
representation of RDF would use literals to insert data for the
resource. The resource could be implied, or explicitly stated.

That would make the RDF implementation cleaner. There would be a
natural way to store the content of any object in a triple: as a
object with a URI.

The implicit URI for literals would be derermined the same way as
other implicit URIs. The content of URLs cold be stored in the
object.

There is no need for a difference between a literal (like a name of a
author) or a URI (pointing to a name of the author ).

Consider this:

  There is no way to know how to parse the literal, exept by
  metadata. The literal could contain the binary data of an image.
  Just like other resources, the literal is the subject of a triple
  specifying the type of the literal. The type can be any object that
  is a subclass to the object Literal. The URI for "image/gif" could
  be one of those literal sub classes.

  There is no way to know how to dereference a resource, exept by
  metadata.  The resource could contain the binary data of an image.
  The similarity to literals goes on. (compare with the paragraph
  above.)


The only difference is one of convinience for the XML representation
of RDF. It is convenient to give a way to embed actual data in the web
of metadata. The distinction between resources and literals is an
effect of this syntax.


But the distinction becomes blured on a higher level.  The RDF Schema
specification is a part of this, as it handles literals as being
instances of the Literal class - that relation in itself beeing
represented in RDF triples.


 * On one hand, you have to know how to parse a literal

 * On the other hand, you have to know how to retrieve a URI


I suggest:

  - that ALL URI's representing retrievable data, will be considerd
    literals.

  - that each mime type will be a sub class to Literal





The retrieval and parsing of data has to be supported by the
implementation. The above suggestion support the decision on how to
parse
the data.

For the XML representation of RDF, there is a clearly defined way to
retrieve the embedded data. But for other URIs, there should be a
way to know how to retrieve the data, as discussed here:

http://paranormal.o.se/perl/proj/rdf/schema_editor/letters/resources.txt


-- 
/ Jonas  -  http://paranormal.o.se/perl/proj/rdf/schema_editor/
Received on Friday, 19 November 1999 20:24:26 GMT

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