[Chameleon] adding several layers from the same external WMS

Bart van den Eijnden
Wed, 24 Dec 2003 17:09:56 +0100
Hi Paul,

just to clarify things.

I have tested whether or not the Web Map Context functionality works 
correctly with the layers=A,B,C,D,E syntax and as you said it works fine. 
Must be an older version of Chameleon in which I saw this fail, or at that 
time I did something wrong.

The most important thing is that the "wms_name" metadata is correct in the 
LAYER definition ("wms_name"	"A,B,C,D,E").

So I will not file a bug for this.

Best regards,

On Wed, 17 Dec 2003 17:47:01 -0500, Paul Spencer <> wrote:

> Yes, we have discussed this performance enhancement internally because 
> of issues another client was having with performance.  The intention, I 
> believe, is to implement the combining 'automagically' in mapserver wms 
> client code, it would detect that more than one layer is coming from the 
> same wms server in the same projection etc and would combine the 
> requests if possible (i.e. if the layers are together).  I don't know if 
> there is a bug in mapserver bugzilla on this or not, but I suspect there 
> is ... in fact it is bug 116, and it has been marked P1 for version 4.1 
> which means that it should get implemented in time for the next release 
> sometime before March (hopefully).
> I have cc'd Bart on this bug.
> Re the combining of layers in a context, I know this works because I 
> have been using it recently.  However, it does cause some funny side 
> effects, like layer transparency doesn't seem to work correctly.
> I would recommend that you create a bug in chameleon on maptools 
> regarding the interaction with the upload/download context and I will 
> try to take a look at it before the release.
> Cheers,
> Paul
> Huub Fleuren wrote:
>> one of the Geodan mapswing components (the java  mApplet) uses a 
>> combine=true setting for this purpose.
>> the applet 'combines' a request to the server if the layers are al from 
>> the same server url into a sigle GET request to the Geodan mapserver
>> in the chameleon/mapserv setup this would have to be done by the 
>> mapserver after reading the map file
>> Huub
>> wrote:
>>> Hi list,
>>> in Chameleon there is the possibility to add layers from a treeview to 
>>> the
>>> map.
>>> In this case if a user adds e.g. 5 layers from the same external WMS, 5
>>> LAYERS are created in the session MAP file, all with a connection type
>>> WMS.
>>> This means 5 requests to the external WMS per Chameleon MAP refresh. In
>>> theory, this could be solved by asking just one image to the WMS server
>>> (layers=A,B,C,D,E). Ofcourse, this has the assumption that the five 
>>> layers
>>> from the external WMS are in sequence on top of each other, and not 
>>> some
>>> other layer in between.
>>> I have also noticed that when using the layers=A,B,C,D,E type of 
>>> syntax,
>>> the Web Map Context (save, upload) does not function any more.
>>> Any thoughts on this, could this be a potential performance enhancement
>>> for Chameleon, and would this require changes in PHP/Mapscript or in 
>>> the
>>> Chameleon PHP code?
>>> Best regards,
>>> Bart
>>> _______________________________________________
>>> Chameleon mailing list


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