[Mapserver-users] querying WMS layer

[bartvde at xs4all.nl]

Hi Gregor,

answers inline.

>
>> You can query your "server-side" layer in most other WMS clients, such
>> as
>> Chameleon, but these don't go through Mapserver WMS client for
>> GetFeatureInfo but call the WMS server directly.
>> A technical story, but I hope you get the drift.
>
> Lemme rephrase to make sure I really get it: "MapServer as a WMS server
> can be queried for feature info. However, there's a shortcoming in
> MapServer's WMS-client so that WMS layers cannot be queried in this
> fashion." Is that right?

Yes this is right. I would not call it a shortcoming though (although I
have called it a shortcoming in the past), but an implementation decision.

>
> If so, is there some other prescribed way of displaying a WMS layer, and
> being able to query that layer?

Not that I know off, you could do some PHP/Mapscript though to get the
connection of the layer (i.e. the URL of the WMS server) and build the
GetFeatureInfo request yourself. This is the approach that Chameleon
follows.

>
> Is this cascading thing an issue for MapServer's WFS implementations
> as well? Could a MapServer WFS-client layer be queried?

I just tried this and you can query a LAYER of CONNECTIONTYPE WFS. So no
problems there, but that's because this is a GML "datastore" just as
shapefile is a "datastore". With CONNECTIONTYPE WMS you cannot access the
data itself as a (WMS) client, that's the big difference.

Best regards,
Bart

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