[Mapserver-dev] WMS: nested groups

[Frank Warmerdam]

Silke Reimer wrote:
> Hallo!
> 
> We are working on a project where we need nested layers in more than
> one level within a WMS server.
> 
> Currently the WMS implementation of the UMN MapServers allows one
> grouping level by assigning a group to several layers. The groupname
> then appears as nested layer into the Capabilities-Document.
> 
> I thought of a possibility how to enhance the UMN MapServer to allow
> more than one grouping level and came to the idea to add a new layer
> type, named 'grouplayer' which is only a virtual layer. Such I can
> define a full tree of nested layers (see example below).
> 
> I made a first implementation of this feature by:
> - including the grouplayer keyword
> - adapting the creation of the Capabilities document.

Silke,

Your approach sounds good to me.  Can you provide an example .map file
showing how a few levels of heirarchy would look?

> You can find the corresponding patch on [1].

The concern I think you will find is that we are now in feature freeze
for the 4.4 release, so incorporating your patch now is more problematic
than it would have been a few weeks ago.

I also notice that your patch is against 4.2, not 4.3/4.4beta.

Of course Steve, Daniel and others are the real authority on WMS and overall
architecture issues, but I think it would be good for you to submit your
patch in bugzilla as an enhancment request for post 4.4 release.  The patch
will need to be reworked somewhat at that time and we might want to discuss
the details of how things would work a bit in the bugzilla bug report a bit
before it is implemented.

> I would like to have some feedback from your side whether you think
> that this is sensible. Furthermore there are still a few open
> issues:
> - what is about nested layers of the wfs and wcs? Probably this code
>   has to be adapted as well (this has not been important for my
>   implementation so I left it out so far).

My understanding is that WCS and WFS do not support a concept of
nesting.  That is, the spec doesn't support it, not just MapServer.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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