groups and WMS

[Armin Burger]

You're right. I cannot reproduce that exception any more so it might 
have been related to a mis-configuration of the server or the client 
test request.

But still I think that the MapServer GROUP definition should not be 
broadcasted via WMS getCapabilities as set of different layers by 
default. So one can use internally any logic one intends to. For me 
scale-depending layers of different accuracy/resolution grouped together 
with GROUP seem important. But a client should just see one layer.

The mechanism of grouping and nesting layers should be performed via 
separate tags, like currently already the WMS_LAYER_GROUP, but also with 
possibilities that this group is selectable.

Armin

Yewondwossen Assefa wrote:
> 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
>>
>