Re: [topicmaps-comment] referring to a topic from outside a TM(was:multilingual thesaurus - language, scope ,and topic naming constraint)

["Thomas B. Passin" <tpassin@comcast.net>]

Right- xlink uses XPointers.  However, the form xxx#yyy is an xpointer
shortcut that means #xpointer(id(yyy)), as long as "yyy" actually is the
value of an attribute of type ID.  Thus the use of xlink:href="#yyy" in a
topicRef is a perfectly normal and correct use of xlink/xpointer, and refers
to an ID in the same document.  YOur example "
http://psi.ontopia.net/ontopia/ontopia.xtm#topicmap" is also correct
xlink/xpointer syntax, assuming that there is an element with an id element
of that value in the document.

Of course, without a DTD or schema, the processor cannot know whether a
given attribute is of type ID or not.  Some xlink processors assume that an
attribute named "id" is really an ID and treat it as such, some do not.

You said

"Remember there is also a third valid syntax (besides document-anchors and
xpointer): a HTTP GET request like

 http://psi.ontopia.net/ontopia/ontopia?id=topicmap"

That requires a server to understand what is denoted by the query fragment,
and we have no standard for that.  The server is free to retrieve whatever
it chooses to.

Cheers,

Tom P

[Bandholtz, Thomas]

IE does not handle an anchor in an XML doc at all.

Consulting the XLink rec on xlink:href
(http://www.w3.org/TR/2001/REC-xlink-20010627/#link-locators), I found
something interesting:
<<<<< For locators into XML resources, the format of the fragment identifier
(if any) used within the URI reference is specified by the XPointer
specification [XPTR]. >>>>>

(The "fragment identifier"  into HTML resources is the anchor indicated by a
leading '#' like in the above (not-working) example).

I just started to re-read XPointer
(http://www.w3.org/TR/2001/WD-xptr-20010108/).  Following this spec i should
have used:

 http://psi.ontopia.net/ontopia/ontopia.xtm#xpointer(id('topicmap'))

IE does ignore this anchor either. A look at http://www.w3.org/XML/Linking
shows that all this is just standardized (w3-rec) but not widely implemented
yet.

Anyway: I think that the syntax (HTML-style).

 http://psi.ontopia.net/ontopia/ontopia.xtm#topicmap

should be replaced by the XPointer syntax to be synchronized with the
standardization process.

 As far as i have understood, this will still be a valid value for an
xlink:href attribute (as it is an URI). So it conforms with the XTM DTD.

Remember there is also a third valid syntax (besides document-anchors and
xpointer): a HTTP GET request like

 http://psi.ontopia.net/ontopia/ontopia?id=topicmap.

This would require not a document at all, but some server processing at
http://psi.ontopia.net/ontopia/ontopia.

(You can also specify a HTTP-GET binding for a Web Service, BTW).

Thomas Bandholtz
XML Competence Center
SchlumbergerSema
Sema GmbH
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