[Mapbender-users] RE: recommendation for grouping layers

karsten vennemann karsten at terragis.net
Fri Jan 11 03:50:38 EST 2008

Hi I tried to experiment with both options
1. using ConfTreeGde to group layers into folders
2. using TreegGde2 and multiple local wms to group layers into different
(see also message below)

I didn't come up with a conclusion yet what is better regarding performance
( I have 90 layers and a map file with 5000+ lines), but it seems that
mapbender is using stacking multiple transparent images on top of each other
to assemble the map. Is that correct ?
In that case this could have performance advantages if only switching off
one group (WMS) during work with the maps and the other wms stay untouched -
mapserver has to render fewer layers this way when a user switches off
However on the other hand initially loading multiple wms could slow down
performance initially during the start of the session (compared to option
1)? Did anybody ever compare those or has  thoughts on that ?

Also in the documentation I read about treeGde2 at
http://www.mapbender.org/index.php/TreeGDE2 : "Group information (nested
layers) is already available in the database but is not used to display in
Is there anybody that tried to accomplish nested layers (one level is enough
for my purposes) in treeGde2?
Or could anybody point out what would be involved adding that (I might give
it a shoot, even being new to mapbender). It sounds that the database
already has some of the information needed to do that.


From: karsten vennemann [mailto:karsten at terragis.net] 
Sent: Monday, January 07, 2008 18:05
To: 'mapbender_users at lists.osgeo.org'
Subject: recommendation for grouping layers


in my project only local wms will be used and I wanted  to ask your opinions
on the best way to do the group of the layers.

The original map file's (on a MapServer only WebMap) layers are already
grouped using the MapServer group tags.
Now on the mapbender wiki I have read that I can use the custom tree to
organize and group layers. Thus, I thought I could either produce one wms
and one map file for each group -  or I could stay with one map file and use
the custom tree to do the grouping.
Would there be any advantages / disadvantages to either approach (having one
or multiple wms) ?
Would I have to expect any differences in performance?
How does that work anyway with multiple wms ?
Does mapbender wait for responses from each wms and then assemble one output
image? or would it be multiple transparent images stacked on each other?
This really would be interesting to know.


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