[GeoSciML] WFS querying of properties specified with xlink:href

Sen, Marcus A. mase at bgs.ac.uk
Thu Oct 11 06:43:18 EDT 2012

> -----Original Message-----
> From: Simon.Cox at csiro.au [mailto:Simon.Cox at csiro.au]
> Sent: 10 October 2012 23:28
> To: geosciml at lists.opengeospatial.org; Sen, Marcus A.
> Cc: F.Tertre at brgm.fr
> Subject: RE: [GeoSciML] WFS querying of properties specified with
> xlink:href
> Sorry - I'm joining this thread part way through, so am not clear if
> the concern is around using the values of xlink:href in a query for
> (i) feature references
> (ii) concepts
> (iii) both.
Our immediate concern was concepts (e.g. querying where an olderNamedAge has a value specified by a CGI dictionary URI in the xlink:href attribute. I guess feature references also have to be dealt with in the general case.

> In GML 3.3 there is a clause that clarifies and revises the use of GML
> for
> (a) assigning names and identifiers
> (b) referring to external resources using their identifier.
> Prior to GML 3.3 there was a lot of confusion about this, around the
> elements whose type is gml:CodeType and gml:ReferenceType.
> In GML 3.3 we made it explicit, that references to external resources
> (including concepts) should be serialized using the gml:ReferenceType,
> which means that the reference is carried on an xlink.
> This is consistent with the use of xlinks in the inline-or-by-reference
> pattern, but allows for reference to concepts that are not
> (necessarily) available in a GML serialization.
> Given this recommendation, I guess there shuld be a flow-on change to
> WFS/FES that enables this serialization pattern to be consistent with
> the query.
> My hunch is that the solution should be scalable to both feature-
> references (with some kind of rule about the relationship with a
> gml:identifier value) and concept/vocabulary items (resources denoted
> inherently by URIs under the SKOS model).
OK, given your and Clemens' reply (which you may not have seen but basically concluded that it is at least arguably allowable to allow @xlink:href in the current FES spec.) I think I can ask Snowflake to revert their software to the previous behaviour accepting @xlink:href which we currently depend on.

The details of how the specs should be worded in future versions I guess will continue to need to be discussed.


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