[MapProxy] Two GetFeatureInfo issues

[Oliver Tonnhofer]

Hi Anne,

On 01.10.2010, at 18:53, Anne Blankert wrote:
> 1. For some reason MapProxy wants the WMS GetFeatureInfo client to provide some extra WMT parameters?
> When sending a GetFeatureInfo request like:
> http://192.168.25.189:8080/service?&SERVICE=wms&VERSION=1.1.0&REQUEST=GetFeatureInfo&EXCEPTIONS=application/vnd.ogc.se_xml&SRS=EPSG:900913&BBOX=515852.005913,6855223.828258,563395.837497,6885492.891453&X=205&Y=223&INFO_FORMAT=application/vnd.ogc.gml&FEATURE_COUNT=1&QUERY_LAYERS=dnk&LAYERS=dnk&WIDTH=622&HEIGHT=396
> 
> The response is:
> <WMTException version="1.0.0">missing parameters ['wmtver', 'styles', 'format']</WMTException> 

At first, MapProxy does not support 1.1.0. So it seams there was a problem during version negotiation. MapProxy falls back to 1.0.0, hence the exception about the missing wmtver parameter. styles and format are also required by the WMS specification and the WMTException is the correct answer to this request.

We are still not sure how to handle these clients in general: Sniffing the user-agent would be a solution, or just ignoring the missing parameters.
Until then, you could use the undocumented 'wms.non_strict' option. It will ignore styles and format parameters if you set it to True in the proxy.yaml.

> If I am correct these parameters are not normally required for WMS GetFeatureInfo requests?

The format, not so much, but the style can affect the request (e.g. x,y might hit a thick line, but not a thin line). Regardless of that, they are required by the spec.

> 2. If the remote WMS webservice uses an other projection than the MapProxy client, the MapProxy GetFeatureInfo request sends the BBOX parameters of the client projection instead of the remote projection to the remote server. The BBOX parameter probably should be reprojected from client to remote projection. I am not sure if the x, y, width and height parameters should be changed because of the re-projection.

The width and height changes so that the request has square pixels. And with a different projection, x and y move in the image. The coordinates are transformed correctly in that case.

Regards,
Oliver

-- 
Oliver Tonnhofer <olt at omniscale.de>
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