[mapserver-users] WMS Layers and Grouping (FWD)

[teb]

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Date: Wed, 19 Sep 2001 16:16:00 -0700
From: Paul Ramsey <pramsey at refractions.net>
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To: mapserver-info at lists.gis.umn.edu
Subject: WMS Layers and Grouping
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There are a couple issues around the translation from a mapserver map
file and the WMS capabilities file which I am wondering about:

- The WMS Capabilities includes the ability to "nest" layers, such that
one could have a description like this:
  <Layer>
    <Title>Water Features</Title>
    <Name>water</Name>
    <Layer>
      <Title>Rivers</Title>
      <Name>rivs</Name>
    </Layer>
    <Layer>
      <Title>Lakes</Title>
      <Name>lks</Name>
    </Layer>
  </Layer>

  This would be kind of cool to be able to do. Using the mapserver
  'group' idea to implement this is possible. However, I have another
  question regarding 'group', and it goes like this:

- Oftentimes, people will use the mapserver 'group' to provide one
  "virtual" layer made out of a whole bunch of scale-dependant layers.
  So, you have a group 'roads' which consists of 1:6Million roads 
  at full extent, 1:250K roads partway in, and 1:20K roads at max
  zoom. Right now, mapservers WMS will report all the constituent
  layers of this virtual layer in the Capabilities file, like 
  this:

  <Layer>
    <Title>roads_6M</Title>
  </Layer>
  <Layer>
    <Title>roads_250K</Title>
  </Layer>
  <Layer>
    <Title>roads_20K</Title>
  </Layer>

  When really, as a map publisher I would prefer to just expost 
  the thing as one virtual layer, thusly:

  <Layer>
    <Name>Roads</Name>
  </Layer>

So, two different problems, but I do not have a clean solution in my
head in terms of mapping file syntax, to allow these kinds of WMS
constructions from a map file.

-- 
      __
     /
     | Paul Ramsey
     | Refractions Research
     | Email: pramsey at refractions.net
     | Phone: (250) 885-0632
     \_

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