groups and WMS

[Yewondwossen Assefa]

Armin,

  In Mapserver if you have 2 wms layers that are in the same group you 
should be able to do a GetMap request using he group name  but also on 
the individual layers. You should not get an exception for trying to 
fetch an individual layer belonging to a group.

Later,

Armin Burger wrote:
> Dear all,
> 
> I have a question about the behaviour of groups in a WMS. When I define 
> 2 layers belonging to the same group, I see both layers nested under the 
> same group layer in the capabilities file.
> 
> But I can only access the group as a WMS layer from a client. When I 
> want to access the single layers belonging to that group I get an 
> exception. That is in principal ok, but client programs might allow to 
> select the single nested layers and the map will not be displayed 
> because of the exception. Also the reason for grouping layers is quite 
> often to have layers with different accuracy/resolution that should be 
> swapped depending on the scale. So this should happen behind the scenes 
> without the client noticing it.
> 
> So my question is, why are the layers belonging to the same group 
> displayed at all in the WMS capabilities if they cannot be used as 
> single ones? Would it not make sense to just return the group as a WMS 
> layer instead?
> 
> Armin
> 

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Assefa Yewondwossen
Software Analyst

Email: assefa at dmsolutions.ca
http://www.dmsolutions.ca/

Phone: (613) 565-5056 (ext 14)
Fax:   (613) 565-0925
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