[mapserver-users] The GetFeatureInfo return a GML without a validation schema.

Tue Aug 14 00:05:04 PDT 2012

Hi Jukka.

I start to try to put a GeoJSON response, but seem it need a dedicated
template.
However after I found a better (for me) solution using the GML.

It allow to response with a multipart response.
This mean it send 1 response with two file inside it.

So I send a GetFeatureInfo and MapsServer using ogr  send me a response
multipart where the first part (first file) is the XSD and the second part
(the second file) is the GML data.

This a good solution for me because I send both: The GML and the xsd.
Also this GML is generated using OGR and so it is preferrable (for me)
because it use the featureCollection and is perfectly understanted from
GeoTools ( a library we are using).

The mapfile setting to obtain it is this (from the documentation of
mapserver):

  OUTPUTFORMAT
    NAME "OGRGML"
    MIMETYPE "text/gml"
    DRIVER "OGR/GML"
    FORMATOPTION "STORAGE=filesystem"
    FORMATOPTION "FORM=multipart"
  END

and in the metadata section of Layer is need to put this:

      "wms_getfeatureinfo_formatlist" "OGRGML,OGRGEOJSON"

Thx for your really useful hints.

Regards,

Andrea.

2012/8/13 Rahkonen Jukka <Jukka.Rahkonen at mmmtike.fi>

> Andrea Peri wrote:
>
> > Hi,
> >>If GetFeatureInfo would produce GML with different schema than WFS
> GetFeature, how the users are supposed to read it? WMS does not have request
> >>"DescribeGetFeatureInfoSchema" and building such for Mapserver does not
> feel optimal. So the GetFeatureInfo GML should have a link to a static
> >>schema file that could be accessed through the web.
>
> > Yes this was an option, but it is not the only.
> > Another option could be an "Inline XML". It is an XML with it xsd
> embedded.
> > http://www.herongyang.com/XML/XSD-Statements-Embedded-in-XML-File.html
>
> GDAL/OGR can write such GML files but documentation warns that they may
> not be valid. You can try with ogr2ogr for example with the following
> command. If there is some troubles with my WFS you can use any other vector
> format as input.
>
> ogr2ogr -f GML -dsco XSISCHEMA=INTERNAL test.gml
> "wfs:http://hip.latuviitta.org/cgi-bin/tinyows" -sql "select * from
> municipalities where kunta_ni1='Helsinki'"
>
> If the resulting GML seems good to you I would guess that someone here can
> tell how to configure Mapserver to use that kind of output for
> GetFeatureInfo. Formatoptions in OGR output settings seem promising to me
> http://mapserver.org/output/ogr_output.html
>
> >>How about forgetting GML and use something that does not need separate
> schema file, perhaps  GeoJSON?
>
> > I guess GeoJSon is no a consolidated standard.
> > So I guess the GeoJSON generated from geoServer is different from the
> GeoJSON of MapServer or of other products.
> > Our goal is to write routines able to speak with MapServer mainly with
> MapServer but also with GeoServer or others WMS systems.
> > The routins must be able to retrieve attributes and geometry.
> > We don't want use the WFS because it is too much oriented to a download.
> It is not lockable to give one only instance (one only > geometry)
>
> I am not a specialist with standards but if GeoJSON and JSON standards
> together take something like 430 pages less than GML it is possible that
> there are less possibilities for different interpretations.
> http://geojson.org/geojson-spec.html
> http://www.ietf.org/rfc/rfc4627.txt
> http://www.opengeospatial.org/standards/gml
>
> If you are going to discuss with servers which are not managed by yourself
> you may meet some troubles with WMS GetFeatureInfo. WMS standard says very
> little about GetFeatureInfo output formats.  Mainly it is just that the
> formats must be advertised in the WMS GetCapabilities.
>
> Limiting results from WFS to only one result is not a problem, you need
> just add &MAXFEATURES=1 to the request.  The main problem when it comes to
> interactive web mapping use is that WFS does not have request for getting
> the closest feature from a given coordinate.
>
> -Jukka Rahkonen-
>
> >>2012/8/10 Rahkonen Jukka <Jukka.Rahkonen at mmmtike.fi>
> >>Hi,
>
> >>DescribeFeatureType is compulsory part of WSF so it is no wonder that it
> works automatically.
>
> >>I try to think what could be done. DecribeFeatureType must match with
> WFS GetFeature. It you would like to use DFT with WMS GetFeatureInfo then
> GetFeatureInfo could not be separately configurable. It should always use
> the schema defined for WFS.
> I suppose that this is how Geoserver works. I also believe that there are
> Mapserver users who want to get different GML from WFS GetFeature and WMS
> GetFeatureInfo.
>
> >>If GetFeatureInfo would produce GML with different schema than WFS
> GetFeature, how the users are supposed to read it? WMS does not have
> request "DescribeGetFeatureInfoSchema" and building such for Mapserver does
> not feel optimal. So the GetFeatureInfo GML should have a link to a static
> schema file that could be accessed through the web.
>
> >>OGR GML driver seems to be able to create such schema file automatically
> with XSISCHEMA=EXTERNAL option http://gdal.org/ogr/drv_gml.html.
>   Problem is that probably you do not want to send two files for the WMS
> client doing GetFeatureInfo calls (xml + xsd), not even zipped into one
> archive file. So OGR should generate .xsd file, store it into some place on
> the server and write a corresponging URL into the GML part of response so
> that client could read the file through the web. It feels complicated but
> probably it could be done.  XSISCHEMA=INTERNAL would be much more simple
> both on the server and client side but documentation tells that it does not
> work.
>
> >>How about forgetting GML and use something that does not need separate
> schema file, perhaps  GeoJSON?
>
>
> -Jukka-
>
> Andrea Peri wrote:
>
> Hi Jukka,
>
> That option ask the user to produce itself all the schemas for all the
> layers
>
> I see instead that a getFeature request on the WFS section will produce
> automatically an xsd of the GML it return using the DescribeFeatureType
> request.
>
> I hope to find a solution to have this automatically produce also on the
> GetFeatureInfo.
> 2012/8/10 Rahkonen Jukka <Jukka.Rahkonen at mmmtike.fi>
> Hi,
>
> Would it work as you hope if the creation option "XSISCHEMAURI" could be
> set as described in the OGR GML driver page
> http://gdal.org/ogr/drv_gml.html?
>
> "XSISCHEMAURI: If provided, this URI will be inserted as the schema
> location. Note that the schema file isn't actually accessed by OGR, so it
> is up to the user to ensure it will match the schema of the OGR produced
> GML data file."
>
> -Jukka Rahkonen-
>
> Andrea Peri wrote:
>
> Hi,
>
> doing a GetFeatureInfo of GML type I see the MapServer send this kind of
> response.
>
> <msGMLOutput
>      xmlns:gml="http://www.opengis.net/gml"
>      xmlns:xlink="http://www.w3.org/1999/xlink"
>      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
>     <rt_cat.idcatbdfog.rt_layer>
>
> Unfortunately this response don't has a schemaLocation with a xsd for
> validation available.
>
> I try with the DescribeFeatureType, but it return an xsd for a
> featureCollection (for GML from WFS) don't for the msGMLOutput.
>
> Is possible to set the GetFeatureInfo from mapserver to have a GML
> response validable with the xsd from DescribeFeatureType ?
>
> Thx,
>
> --
> -----------------
> Andrea Peri
> . . . . . . . . .
> qwerty àèìòù
> -----------------
>
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>
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> Andrea Peri
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> qwerty àèìòù
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>
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> Andrea Peri
> . . . . . . . . .
> qwerty àèìòù
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-- 
-----------------
Andrea Peri
. . . . . . . . .
qwerty àèìòù
-----------------
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