[Mapserver-dev] MapServer and OGC services

[Daniel Morissette]

Tom,

I would tend to agree with you on the fact that there is an issue there,
but unfortunately I don't think the solution is simple.  When I
implemented the WFS it really bugged me to have to create duplicate
metadata names for things like wms_title and wfs_title, and I thought
about coming up with something more generic such as ows_title (OGC Web
Service Title), etc.  Perhaps I should have done it, but I wasn't
convinced that this was good enough to justify breaking with the past so
I just ended up going the easy route and went with wfs_* metadata names.

Note that in some cases someone might want to use different values for
some parameters depending on server types.  This may not be very common
for layer names and titles, but for instance the SRS don't work the same
way in WMS and WFS, so someone might want to set different values for
wms_srs and wfs_srs.

Perhaps the best would be to allow a combination of both, i.e. if you
set "ows_title" then that applies to any OGC web service, but you have
the option to set server-specific values using the service name as
prefix, e.g. "wms_title" or "wfs_title" in this case.

So to reuse your example, you could have:

 LAYER
  NAME roads
  METADATA
   "ows_title" "road network"
   "wms_abstract" "Abstract that applies to WMS only"
   "wfs_abstract" "Abstract that applies to WFS only"
  END
 ...
 END


What do you (and others) think?

Another question: do we need the "ows_" prefix or not for the generic
metadata value?  It may be nice to have to indicate that this metadata
applies to OGC web services, but OTOH we may end up with the same
problem later on when we decide to support other uses for this
metadata.  I'm really not sure what's best.

Daniel



Tom.Kralidis at ccrs.nrcan.gc.ca wrote:
> 
> Hi,
> 
> I'd like to provide a few comments w.r.t. MapServer current and forthcoming
> support of OGC services, and development of them.  This comes after I set up
> a WMS with MapServer, and was looking to set up WFS as well.
> 
> Currently, MapServer provides WMS publishing by means of directives through
> the mapfile, whose structure is basically "wms_<parameter>" "value".
> Populating these fields produces the appropriate information to respond to
> an OGC WMS GetCapabilities request.
> 
> According to the following wiki:
> 
> http://mapserver.gis.umn.edu/cgi-bin/wiki.pl?WFSMapServer
> 
> ..one can have WFS functionality also by using a similar nomenclature, i.e.
> "wfs_<parameter>" "value", in various areas of a mapfile.
> 
> Having said this, I find myself adding directives with the same information
> in order to publish as WMS and WFS, i.e.
> 
> LAYER
>  NAME roads
>  METADATA
>   "wms_title" "road network"
>   "wfs_title" "road network"
>  END
> ...
> END
> 
> While this may not be a huge deal, given the limited OGC services supported
> by MapServer, what happens when MapServer supports other OGC services,
> current and / or forthcoming?
> 
> Perhaps an abstracted model and approach should be put forth in the mapfile?
> i.e.
> 
> LAYER
>  NAME roads
>  METADATA
>   TITLE "road network"
>   ABSTRACT "This is a road network"
>   ...
>  END
> ...
> END
> 
> This would streamline the approach for those populating mapfiles; also the
> software can fork out the information, depending on the type of request it
> gets (i.e. services=wms|wfs|...).  I guess what I'm saying is that thought
> should be given to MapServer working with this information independently,
> and not having to add parameters according to specs, yet publish information
> as per the spec using the internal model of the mapfiles.
> 
> Comments?
> 
> ..Tom
> 
> =================================
> Tom Kralidis
> Systems Scientist
> Canada Centre for Remote Sensing
> Tel: (613) 947-1828
> http://www.cgdi.ca/
> =================================