Call for comments -RFC 39

Frank Warmerdam warmerdam at POBOX.COM
Thu Nov 15 10:22:08 EST 2007

Yewondwossen Assefa wrote:
> Hi all,
>  I have put together an RFC outlining changes that could be done to be 
> able to support Named styles in WMS/SLD. I would appreciate your 
> comments on it:


I've read it over and it seems reasonable, but I'm not clear on whether
CLASSes are the right level to break out styles.  I can imagine two

1) Do it at the layer level.  Basically if you want a WMS layer to support
two styles, create two different layer objects, and somehow declare style
names for them with a new keyword.  There is already a way of grouping
mapserver layers together to appear as a single WMS layer, right?

One benefit of this approach is that it would also be possible to offer
different styling options that don't directly map to classification.  For
instance, you could have raster layers that use different scaling options
(not based on classification) represented as distinct styles via WMS.

2) Do it at the STYLE level.  Actually declare style names in the styles
and have these selectable in a somewhat similar fashion to what you are


One concern I have with your approach, and with option "2" is that in a
multi-style layer, the default rendering will be a sort of mis-mash of
the styles since the default is that all classes are in effect.  Perhaps
if multiple styles are defined, the default (WMS and regular mode) would
be to use the first of the styles instead of all of them.

I don't have an iron in this fire, so I don't feel strongly about this.
I'm just trying to throw up a few options based on mild unease with the
presented solution.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at
light and sound - activate the windows |
and watch the world go round - Rush    | President OSGeo,

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