[nvo-techwg] Referencing in XML for the IVO

[Arnold Rots]

Paul Harrison wrote:
> Arnold Rots wrote:
> > Appended is something that will work (and that I showed at the team
> > meeting in abbreviated form).  It has URLs instead of IVO identifiers
> > but that's a detail.
> > 
> 
> 
> I am not convinced that it is "just a detail" - I think that it is a 
> crucial detail if we are to have any hope of standard xml tools being 
> able to interpret such documents.
> 
> The ivo: scheme is an URI, so a registry must be used to actually locate 
> the document, which is a two stage process, as the ivo: URI first gets 
> resolved into an xml instance conforming to the Registry schema, which 
> in itself contains a link to the URL of the xml instance fragment 
> conforming to the STC schema. This double indirection should really be 
> expressed in the source xml document - possibly with the help of 
> Xpointer (http://www.w3.org/TR/2002/PR-xptr-framework-20021113/)

Point well taken.  It was a detail in the context of what I was trying
to show Roy, but it certainly is an issue that needs some discussion.
I'd be happy to go with either exclusive URLs or URIs, or both, but I
suspect the point is that there are certain references that cannot be
expressed through a URL.  I think this is a job for Ray Plante :-)

> 
> Having said all this, Xlink and Xpointer do seem to have stalled in 
> developement somewhat - there seem to be few (if any) general 
> implementations - possibly because once you allow more complex semantics 
> for a link than simply "go there" it is difficult to build a general engine.

Yes, I agree; and it may well be that they are indeed more suited for
use within a limited user community like the IVOA, where the fully
general engine is not required.

> 
> 
> 
> -- 
> Paul Harrison
> ESO Garching
> www.eso.org
> 
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Arnold H. Rots                                Chandra X-ray Science Center
Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
60 Garden Street, MS 67                              fax:  +1 617 495 7356
Cambridge, MA 02138                             arots at head.cfa.harvard.edu
USA                                     http://hea-www.harvard.edu/~arots/
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