Re: The role of media types for XML content

[Mark Baker <distobj@xxxxxxx>]

Hey,

On Sat, Jun 11, 2005 at 03:50:03PM +0900, MURATA Makoto wrote:
> Mark> >Although 
> Mark> > your example can be addressed by specialized media types, my example 
> Mark> > (schemas embedded within XHTML are referenced by XPointer) cannot.
> Mark> 
> Mark> Can you elaborate on that example please?  I don't think I've seen any
> Mark> schemas embedded in XHTML before.
> 
> Consider the following XML document (say multi.xml).  This example is not 
> artficial.  It is useful for literate programming.  As you know better
> than me, W3C is trying to promote compound documents.

Right.  For those who weren't aware, the W3C has a Compound Document
Formats WG[1] that is trying to address some of these issues.  I'm on
the WG as a representative of Justsystem Corp.

> I would like to reference to the embedded RNG schema using multi.xml#rng. 
> What is the media type of this document?

You could use the text/html or application/xhtml+xml media types.  If
fallback rendering was a problem, you could add some styling directives,
or else just "display: None"-it and place an HTML description in there.
Fragment identifiers would work as expected.

You could use application/xml too, though as you know, you don't get
fragment identifers.  Also, IE doesn't make the same assumptions as
other browsers[2], and will only display the tree view.  Moreover, the
interpretation made by these other browsers isn't licensed by RFC 3023;

  An XML document labeled as text/xml or application/xml might contain
  namespace declarations, stylesheet-linking processing instructions
  (PIs), schema information, or other declarations that might be used
  to suggest how the document is to be processed.  For example, a
  document might have the XHTML namespace and a reference to a CSS
  stylesheet.  Such a document might be handled by applications that
  would use this information to dispatch the document for appropriate
  processing.

The CDF WG may or may not be defining a media type that is suitable for
what you need (I can't say until we publish), but I can say with
certainty that it isn't currently supported by any existing agent. 8-)

If it were me, I'd go with text/html if there was a reasonable
expectation that somebody with IE might want to plug a URI that returns
one of these documents into their location bar.  Otherwise I'd use
application/xhtml+xml.

>And do you want to specify a 
> specialized media type when you reference the embedded RNG?

Ideally, yes, I think that would be valuable for the reasons I gave
before concerning layering and security.

 [1] http://www.w3.org/2004/CDF/
 [2] http://www.markbaker.ca/2004/01/XmlDispatchTest/

Mark.
-- 
Mark Baker.  Ottawa, Ontario, CANADA.          http://www.markbaker.ca
Coactus; Web-inspired integration strategies   http://www.coactus.com