Re: [xtm-wg] DTD XLink thought

["ann.wrightson" <ann.wrightson@leedsalumni.org.uk>]

Many thanks for this Murray - I've been trying to get my head round it, & not
getting to clarity!

Cheers

Ann W.

Murray Altheim wrote:

> Graham Moore wrote:
> >
> > Could Association be treated as an exteneded link with role being xlink
> > locators. I think this is a useful way of seeing things.
>
> Graham,
>
> I think you're very correct in the understanding of this, but after
> spending many hours with XLink I've found that there's no way to actually
> XLink extended links. There are many reasons why only simple links
> can be used, and I'd be happy to discuss this with you at length, but
> I'm sure the time for both of us is very limited. I'd hoped to do this
> at the Dallas meeting, but time was short. I wrote up several sample topic
> maps for myself and spent probably twelve hours on Xlink syntax, ending in
> frustration.
>
> First good reason: XLink elements cannot be deeper than child level
> or they lose their definition in XLink. No deeper containment is
> defined. Secondly, arcs are only valid within their extended link
> container, yet arc elements must be children, not descendants, ie.,
> they can't be nested even as deep as grandchild. I even found that
> xlink:title doesn't work for us for the same reasons (eg., the
> <baseNameString> element is a grandchild of <topic>, so <topic> wouldn't
> even see it). And you can't have xlink:extended inside of xlink:extended
> for a similar reason: there's no semantic defined, so XLink engines
> wouldn't provide us what we need here either. *sigh*
>
> All of my attempts at syntax for this in XTM failed to be compatible
> with both XTM requirements and XLink. I spent some time with Eve Maler
> (an editor of XLink) on this, and I think simple links are all we can use.
> Sadly. I'd really hoped to promote XLink's more complicated structures,
> but neither Eve or I could come up with something that worked. We ended
> up with a much easier syntax pedagogically, in that we only have three
> kinds of links: <resourceref> to point to resources, <topicRef> to point
> to <topic> elements, <subjectRef> to point to things that are the subject
> of a topic (referent="isSubject" in our older syntax), and finally
> <subjectDescRef> to point to things that describe a topic (the
> referent="describesSubject" of olde).
>
> We still have the legacy of <mergeMap>'s old syntax, which should
> probably be a container for <resourceRef>, but I'm okay with <mergeMap>
> itself being a link since it's probably fairly rare to use it for 90%
> of people using topic maps.
>
> Murray
>
> ...........................................................................
> Murray Altheim, SGML/XML Grease Monkey     <mailto:altheim&#64;eng.sun.com>
> XML Technology Center
> Sun Microsystems, 1601 Willow Rd., MS UMPK17-102, Menlo Park, CA 94025
>
>       In the evening
>       The rice leaves in the garden
>       Rustle in the autumn wind
>       That blows through my reed hut.  -- Minamoto no Tsunenobu
>
>
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