[mapserver-users] How to pimp WMS meta information?

[Kralidis,Tom [Burlington]]

> -----Original Message-----
> From: mapserver-users-bounces at lists.osgeo.org 
> [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of 
> Jochen Topf
> Sent: 25 September, 2008 9:49 AM
> To: Markus Spring
> Cc: Mapserver-users
> Subject: Re: [mapserver-users] How to pimp WMS meta information?
> 
> On Tue, Sep 16, 2008 at 07:16:03AM +0200, Markus Spring wrote:
> > trying to set up a multi-map service based WMS mapservices and 
> > OpenLayers, I would like to retrieve user-defined meta information 
> > from a map via the GetCapabilities request.
> >
> > For example, if I define
> >
> >    METADATA
> >       WMS_TITLE                   "Palliativstationen"
> >       WMS_ONLINERESOURCE          "http://gis.local/wms/palliativ"
> >       WMS_SRS                     "epsg:31468"
> >
> >       WMS_SHOW_QUERY_IN           "large_popup"
> >
> >     END
> >
> > I would like to retrieve the value "large_popup" of 
> WMS_SHOW_QUERY_IN 
> > through the GetCapabilities call. The background idea is that this 
> > information could be used by my application but should not 
> harm other 
> > people's use of the WMS service.
> >
> > Is there any viable way to accomplish this with a mapserver 
> based WMS service?
> 
> I have used the WMS keywords on a WMS layer to add special 
> infos only needed for my application. Not the cleanest 
> approach, because other applications will, of course, also 
> see those special keywords you put in, but as a workaround it is ok.
> 
> Would be nice if there was an "official" way to do this, though.
> 

Out of the box, MapServer will return a well-formed, valid XML document
which obeys the WMS standard.

Having said this, you could use mapscript WxS
(http://mapserver.gis.umn.edu/docs/howto/wxs_mapscript) to, on
GetCapabilities, intercept the request/response mechanism and write out
a modified GetCapbilities XML document, adding in your own XML elements
and definitions, i.e.:

<Layer>
 <Name>foo</Name>
 <Title>bar</Title>
 <MyProperty name="WMS_SHOW_QUERY_IN">large_popup</MyProperty>
...

This would work, with the assumptions that:

1./ a WMS Capabilities parser which is doing DTD checking would choke on
this, as it is not part of the WMS DTD
2./ if there is no DTD checking, the Capabilities will be processed,
only 'aware' clients would know what to do with this info

Of course, if you want to be to-spec 100%, there are ways to extend DTDs
with inline ENTITY's, etc. :)

Hope this helps.

..Tom