PROJECTION block requirements for OWS support

[tomkralidis]

This originated from #2538, comment 6:

"""

I have established that the request reprojection does not work because the layer lacks a PROJECTION block defining it's coordinate system.

If I add:

    PROJECTION 
      "+init=epsg:26915"
    END 

to the layer things work right.

So fundamentally I think the issue with this ticket is that WCS (and possibly other services) need to recognise the map lacks key information and refuse to operate with some sort of explanatory exception.

Alternatively we could try to derive some rules like defaulting layer and/or map projection objects based on stuff like ows_srs.

I don't have any strong opinions, so I don't plan on further work on this issue pending a clear resolution.

"""

The issue here is that we should enforce some sort of projection checking before proceeding with any OWS Server type operation. Perhaps:

if (! LAYER/PROJECTION)
  if (! MAP/PROJECTION)
    throw ExceptionReport saying for mapfile to set PROJECTION, etc.

[dmorissette]

I believe WMS already does something like this in mapwms.c's msWMSLoadGetMapParams(). We should check that before designing another approach.

[bartvde]

AFAICT Mapserver WMS still outputs the warning in the GetCapabilities? even if there is a PROJECTION block at the MAP level (from which layers inherit).

[dmorissette]

Note that there are ticket #2254 and ticket #2028 about the warning misbehaving sometimes and which are only indirectly related.