[gdal-dev] GML / NAS code redundancy

Even Rouault even.rouault at mines-paris.org
Tue Mar 18 09:50:39 PDT 2014


Selon Martin Landa <landa.martin at gmail.com>:

> Hi,
>
> 2014-03-18 17:25 GMT+01:00 Even Rouault <even.rouault at mines-paris.org>:
>
> >> right, after digging into the code I discovered that `featureType`
> >> from `gml_registry.xml` is checked only in header (first 2048 bytes)
> >> [1]. This check fails in my case because features are not included in
> >> szHeader buffer. Could be that I overlooked something...
> >
> > Ah, well all of this is heuristics, so you could likely increase the buffer
> size
> > if it remains at reasonable size.
> >
> > Another idea, if the patterns to recognize are much further in the file,
> since
> > at that point we know that it is GML, would be to separate the recognition
> of
> > whether it is GML or not (that has succeeded since you reached that point)
> from
> > the recognition of what stuff there is in the GML, in which case you could
> > afford to read more. But namespaces declaration are usually rather at the
> > beginning of the file, so if 2048 doesn't work, perhaps 4096 would do.
>
> here is a sample data [1]. There are 8 feature types -
>
> feature type -> first occurrence in the file
> vf:Obec -> 2383
> vf:CastObce -> 27267
> vf:KatastralniUzemi -> 27774
> vf:Zsj ...
> vf:Ulice
> vf:Parcela
> vf:StavebniObjekt
> vf:AdresniMisto

I haven't looket at the file but from the above, the logic of the application
schema registry would need to be extended since it currently only supports one
feature type per file. You would need to ingest the full file to recognize which
feature types are in it.

>
> Thanks for clarification in advance... Martin
>
> [1] http://vdp.cuzk.cz/vymenny_format/soucasna/20140131_OB_502405_UKSH.xml.gz
>




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