[mapserver-users] Querymap display via WMS interface?

[Tom.Kralidis at ccrs.nrcan.gc.ca]

> -----Original Message-----
> From: Daniel Morissette [mailto:morissette at dmsolutions.ca]
> Sent: Wednesday, August 28, 2002 7:32 PM
> To: Kralidis, Tom
> Cc: 'Neel Smith'; mapserver-users at lists.gis.umn.edu
> Subject: Re: [mapserver-users] Querymap display via WMS interface?
> 
> 
> Tom is correct that at this point GetFeatureInfo can return only GML,
> HTML or plain text.  
> 
> But since the querymap feature is already there and available in
> MapServer, one thing we could do with the WMS interface is that if a
> QUERYMAP is defined in the mapfile then we include image types as
> additional GetFeatureInfo formats in the capabilities... and then if
> someone sends a GetFeatureInfo request with INFO_FORMAT=image/png for
> instance then they would receive the querymap in PNG format with the
> selected objects highlighted.
> 

This is an excellent idea!  Whatever image types are supported in
WMT_MS_Capabilities/Capability/Request/GetMap/Format[] can be offered in
WMT_MS_Capabilities/Capability/Request/GetFeatureInfo/Format[] if QUERYMAP
exists.  Probably means some changes to the GetCapabilities and
GetFeatureInfo interface handling, but the capability is there.



> I've filed this in bugzilla as a potential enhancement for 
> MapServer 3.7
> (http://mapserver.gis.umn.edu/bugs/show_bug.cgi?id=191)
> 
> Daniel
> 
> 
> 
> "Kralidis, Tom" wrote:
> > 
> > > -----Original Message-----
> > > From: Neel Smith [mailto:neelsmith at yahoo.com]
> > > Sent: Sunday, August 25, 2002 9:27 PM
> > > To: mapserver-users at lists.gis.umn.edu
> > > Subject: [mapserver-users] Querymap display via WMS interface?
> > >
> > >
> > > I've recently created a mapserver client as part of a
> > > larger web application implemented with Cocoon.  The
> > > client communicates with mapserver exclusively through
> > > WMS protocols (a requirement for this particular app.)
> > >
> > > For navigational interaction (pan/zoom), mapserver's
> > > graphic output is great;  for queries by clicking, the
> > > data results are great (getting output in GML is
> > > wonderful!) -- but I haven't been able to figure out
> > > how to get graphic output illustrating query results.
> > > I'd like for selected features to be highlighted.
> > >
> > > I know that mapserver can do this but I can't seem to
> > > find anyplace in the WMS protocol where this
> > > functionality might be exposed.  (STYLEs?)
> > >
> > > Can anyone point me in the right direction?  Is it
> > > possible to get the equivalent of mapserver's querymap
> > > output using only the OGIS WMS interface?
> > >
> > 
> > Not per se.  Querying WMS usually involves GML.1, GML.2, 
> plain text or HTML
> > at this point.
> > 
> > The Styled Layer Descriptor (SLD) Specification can help 
> here.  SLD is an
> > OGC technology which allows a client to, along with a WMS 
> request, pass the
> > URL of an XML document describing how to style requested 
> layers.  SLD
> > documents can contain multiple rulesets with flexible 
> criteria such as scale
> > and filter expressions.
> > 
> > When MapServer supports SLD, one will be able to send 
> filters and styling
> > rules in real-time to receive custom maps from an 
> SLD-enabled WMS.  Until
> > then, one can have some middleware which styles XML into an 
> output image.
> > 
> > Hope this helps.
> > 
> > ..Tom
> > 
> > =================================
> > Tom Kralidis
> > Systems Scientist
> > Canada Centre for Remote Sensing
> > Tel: (613) 947-1828
> > http://www.ccrs.nrcan.gc.ca/
> > =================================
>