Also note that gml:id is only mandatory in GML 3.2.1; it was optional in GML 3.1.1. gml:id has type xs:ID which forces uniqueness in a single document. WFS suggests (implies? urges?) that gml:id should be stable and unique for a service, but there is nothing in GML to enforce this. There is nothing in GML to prevent each response from using different gml:ids, as long as they are unique in each response document. The problem is that there is AFAIK no support for gml:identifier in WFS. It is nice to have an indentifier that is globally unique; there is no guarantee that gml:id is.
Kind regards, Ben. On 28/02/17 10:23, Rob Atkinson wrote: > Gml:identifier was introduced for stable id. Gml:id is really meant for > reference with the response document but WFS blurred the line with its > getbyid. > > So it comes down to implementation contracts between service and clients... > force ids to be stable, mirror in gml:identifier and allow wfs call on > ids.. or... specify how stable ids are somehow... or just ignore getbyid > method. > > On Tue, 28 Feb 2017, 8:08 AM Nuno Oliveira <nuno.olive...@geo-solutions.it> > wrote: > >> Hi, >> >> I was investigating a WFS cascading issue when I stepped on this two >> pieces of code (this code is the same in the old WFS store and the new >> one): >> >> https://github.com/geotools/geotools/blob/master/modules/unsupported/wfs-ng/src/main/java/org/geotools/data/wfs/internal/parsers/XmlSimpleFeatureParser.java#L180-L180 >> >> https://github.com/geotools/geotools/blob/master/modules/unsupported/wfs-ng/src/main/java/org/geotools/data/wfs/internal/parsers/XmlSimpleFeatureParser.java#L881-L895 >> >> So if GT is not capable to extract a feature id (FID) from a feature, >> the current feature and all next features are ignored. I checked WFS >> specification and related schemas, GML schemas and searched on GS\GT >> mailing list and I'm not sure I understood correctly all the behavior >> around features FIDs. >> >> My impression is that a feature should always be uniquely identifiable >> by an ID but at the same time nothing in GML seems to enforce that. >> GeoTools on is side seems to also assume that a feature can be always >> uniquely identified by an id (I may be wrong). >> >> Can someone shine a light on this ? >> >> Regarding the WFS cascading behavior, does it make sense to allow the >> user to select an attribute that can be used as FID ? >> >> Regards, >> >> Nuno Oliveira >> >> -- >> == >> GeoServer Professional Services from the experts! >> Visit http://goo.gl/it488V for more information. >> == >> Nuno Miguel Carvalho Oliveira >> @nmcoliveira >> Software Engineer >> >> GeoSolutions S.A.S. >> Via di Montramito 3/A >> 55054 Massarosa (LU) >> Italy >> >> phone: +39 0584 962313 >> fax: +39 0584 1660272 >> mob: +39 333 8128928 >> >> http://www.geo-solutions.it >> http://twitter.com/geosolutions_it >> >> ------------------------------------------------------- >> >> AVVERTENZE AI SENSI DEL D.Lgs. 196/2003 >> Le informazioni contenute in questo messaggio di posta elettronica e/o >> nel/i file/s allegato/i sono >> da considerarsi strettamente riservate. 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The sender >> does not give any warranty or accept liability as the content, >> accuracy or completeness of sent messages and accepts no responsibility >> for changes made after they were sent or for other risks which >> arise as a result of e-mail transmission, viruses, etc. >> >> >> >> ------------------------------------------------------------------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, SlashDot.org! http://sdm.link/slashdot >> _______________________________________________ >> GeoTools-Devel mailing list >> GeoTools-Devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/geotools-devel >> > > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > > > > _______________________________________________ > GeoTools-Devel mailing list > GeoTools-Devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/geotools-devel > -- Ben Caradoc-Davies <b...@transient.nz> Director Transient Software Limited <http://transient.nz/> New Zealand ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ GeoTools-Devel mailing list GeoTools-Devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-devel
