[topicmapmail] xml:base and #foo URIs

[Murray Altheim]

[a minor clarification at the bottom...]

(I,) Murray Altheim wrote:
> Thomas B. Passin wrote:
> [...]
> 
>> and I thought that a bare frag ID would be covered by this too, but
>> apparently not, if we put more credance in RFC Section 4.2.  
>> Personally, I
>> would be happy to get rid of the possibility of using xml:base to affect
>> bare frag IDs. Is anyone actually using xml:base in an xtm file to modify
>> the URI of a bare frag ID?  If not, what other uses in xtm have people 
>> found
>> for xml:base?  Just to shorten URIs in resourceRefs and
>> subjectIndicatorRefs?
> 
> 
> Well, XTM 1.0 (in both the topicmaps.org and ISO versions) only
> declares xml:base on the <topicMap> element, so it's only at a
> document level that it even *can* be declared.
> 
> It occurs to me that we (or at least I) have been talking about
> two different things here, or at very least *I* may have been
> confused about two different things. So, to clarify...
> 
>   1. First, there's IDs within XTM documents:
> 
>       <topicMap xmlns="http://www.topicmaps.org/xtm/1.0/"
>                 xmlns:xlink="http://www.w3.org/1999/xlink"
>                 xml:base="http://www.altheim.com/psi/fruit.xtm">
> *        <topic id="fruit">
>             ...
>          </topic>
> *        <topic id="orange">
>             ...
>          </topic>
> *        <topic id="apple">
>             ...
>          </topic>
>       </topicMap>
> 
>   2. Secondly, there's fragment IDs (IDREFs in a sense) within
>      XTM documents:
> 
>       <topicMap xmlns="http://www.topicmaps.org/xtm/1.0/"
>                 xmlns:xlink="http://www.w3.org/1999/xlink"
>                 xml:base="http://www.altheim.com/psi/fruit.xtm">
>          <topic id="fruit">
>             ...
>          </topic>
>          <topic id="orange">
>             <instanceOf>
> *             <topicRef xlink:href="#fruit"/>
>             </instanceOf>
>          </topic>
>          <topic id="apple">
> 
>          </topic>
>       </topicMap>
> 
> Now, there's hopefully little or no confusion about the former, and
> we're only talking about the latter, right?
> 
> As regards xml:base being used in PSI sets (as in the above example),
> the resolution of "#fruit" in the <topicRef> would resolve to an
> absolute URI of
> 
>     http://www.altheim.com/psi/fruit.xtm#fruit
> 
> given the presence of the xml:base URI. This to me makes sense,
> as (let's say) I put the document at a local directory on my
> laptop
> 
>     file:/home/altheim/work/psi/fruit/fruit.xtm
> 
> I certainly don't want my apples' and oranges' types to be
> 
>     file:/home/altheim/work/psi/fruit/fruit.xtm#fruit
> 
> The xml:base is IMO doing its job.

Just to be clear, I consider the xml:base to be doing its job on
the PSIs themselves, too:

    http://www.altheim.com/psi/fruit.xtm#orange
    http://www.altheim.com/psi/fruit.xtm#apple

so that no matter where this XTM document is placed, its location
is ignored, as the base URI of the document is being set to its
"correct" location by the xml:base attribute.

Murray

......................................................................
Murray Altheim                    http://kmi.open.ac.uk/people/murray/
Knowledge Media Institute
The Open University, Milton Keynes, Bucks, MK7 6AA, UK               .

                                                Moonlight slanting
                                                  through all the
                                                  bamboo forest...
                                                and nightingale song
                                                          -- Basho