WMS interface does not support "dimensions" (additional parameters)

[pagurekd@…]

The current version of MapServer's WMS interface doesn't have any way to
deal with dimensions / additional parameters.  This is specified in the Opengis 
specification on page 19 and Annex C.  This enhancement to Mapserver would 
greatly improve the WMS capabilities, and spare developers the task of 
programming and customizing.  A layer can be set up to use a FILTER, and this 
parameter can be filled using an argument/value pair such 
as "DIM_taxa=Vanessa+cardui" according to the OpenGIS specification.

Thanks,
D. Pagurek

[dmorissette]

Can't be done for 4.0, maybe in 4.1?  Reassigned to Assefa as well.

[assefa]

I think it is a useful addition. We could use the same logic used for TIME 
support :

  - user defines at a layer level the following metadata
     * wms_dimension_<dimension_name> : ex wms_dimension_taxa (using debbie 
example)
     * wms_dimension_taxa_extent : list of valid values
     * wms_dimension_taxa_default : default value
     * wms_dimension_taxa_fieldname : field name to use 

  - the request can then be transformed into mapserver logical expressions and
apply on the Filter on layers that have defined the dimension.

 Setting target milestone to FUTURE. We can revisit this in a future version.

[tomkralidis]

So, for WMS Capabilities, it would map like:

mapfile snippet:

"wms_dimension_taxa"
"wms_dimension_taxa_units" "none" # Dimension/@units is required in WMS Capabilities
"wms_dimension_taxa_extent" "a/z"
"wms_dimension_taxa_default" "m"
"wms_dimension_taxa_fieldname" "taxa_field"

relevant WMS Capabilities snippet:

<Dimension name="taxa" units="none"/>
<Extent name="taxa" default="m" nearestValue="0">a/z</Extent>

...then, on a WMS GetMap, this, as stated, would be a simple filter passed to
MapServer from a WMS client, i.e.:

...&taxa=a&

so mapwms.c would have to scan mapfile to make sure the parameter keyword is
valid, then apply the query.

Having said this, seeing that MapServer supports SLD, can SLD filters handle
this in lieu of new development?

[tomkralidis]

Debbie: WMS and SLD can achieve this functionality at this point in time. Is implementing DIMENSION still desirable in WMS?

[tomkralidis]

Since there hasn't been much traffic on this issue, and that the same results can be acheived with WMS/SLD (which MapServer supports), I am marking this wontfix.