[topicmapmail] ["Jonathan Marsh" <jmarsh@microsoft.com>] RE: XML Base question

Thu, 22 May 2003 23:36:05 +0100

Lars Marius Garshol wrote:
> I got the reply below from Jonathan Marsh after nagging him. Since
> we've discussed this issue on this list I thought it was only fair to
> forward it.
> 
> * Lars Marius Garshol
> |
> | It does not seem to me that XML Base makes it sufficiently clear what
> | to do in the following case:
> | 
> |   <!-- document being read from http://www.example.com/foo.xml -->
> |   <doc xml:base="http://www.ontopia.net/bar.xml">
> |     <!-- ... -->
> | 
> |     <link xlink:href="#baz"/>
> |   </doc>
> | 
> | What does this link resolve to? Is it
> | 
> |   http://www.example.com/foo.xml#baz
> 
> * Jonathan Marsh
> | 
> | Yes, according to section 4.2 of RFC 2396.
> 
> * Lars Marius Garshol
> |
> | I think this should be recorded as an XML Base erratum, and that if
> | the spec is ever revised an example showing the correct behaviour in
> | this case should be added, possibly with a note referring to RFC 2396.
> 
> * Jonathan Marsh
> |
> | I'll pass this on to the XML Core WG as a potential erratum.  I agree
> | that it's a little tricky, although I'm not sure that RFC 2396 is
> | sufficiently unclear to require a change.

Well, that makes absolutely no sense to me whatsoever. What in the
heck is XML Base for then? This doesn't operate in the same way as
HTML's <base> element, and to my recollection it was the HTML WG
that requested the creation of XML Base (which is borne out by a
quote below). HTML's <base> has the following example [HTML4], which
is in direct contradiction to Jonathan's reply:
 >
 >  For example, given the following BASE declaration and A declaration:
 >
 >  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
 >     "http://www.w3.org/TR/html4/strict.dtd">
 >  <HTML>
 >   <HEAD>
 >     <TITLE>Our Products</TITLE>
 >     <BASE href="http://www.aviary.com/products/intro.html">
 >   </HEAD>
 >
 >   <BODY>
 >     <P>Have you seen our <A href="../cages/birds.gif">Bird Cages</A>?
 >   </BODY>
 >  </HTML>
 >
 >  the relative URI "../cages/birds.gif" would resolve to:
 >
 >    http://www.aviary.com/cages/birds.gif

This is the way it has always worked (as far back as HTML 2.0). The XML
Base Recommendation [XMLBASE] states quite clearly in its Introduction:

    "One of the stated requirements on XLink is to support HTML
    [HTML 4.01] linking constructs in a generic way. The HTML BASE
    element is one such construct which the XLink Working Group has
    considered. BASE allows authors to explicitly specify a document's
    base URI for the purpose of resolving relative URIs in links to
    external images, applets, form-processing programs, style sheets,
    and so on."

Murray

[HTML4] http://www.w3.org/TR/html401/struct/links.html#edef-BASE
[XMLBASE] http://www.w3.org/TR/xmlbase/
...........................................................................
Murray Altheim                         http://kmi.open.ac.uk/people/murray/
Knowledge Media Institute
The Open University, Milton Keynes, Bucks, MK7 6AA, UK                    .

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