[OSGeo-Standards] WMS-C and Capabilities

Christopher Schmidt crschmidt at metacarta.com
Tue Aug 26 09:08:54 EDT 2008

On Tue, Aug 26, 2008 at 10:36:37AM +0200, Andrea Aime wrote:
> Jody Garnett ha scritto:
> >Just a quick confirmation; the WMS-C page here:
> >- http://wiki.osgeo.org/wiki/WMS_Tiling_Client_Recommendation
> >
> >Has confused a couple implementations; my understanding is this 
> >specification talks about adding to the VendorSpecificCapabilities of an 
> >existing WMS server a section describing the available TileSets.
> >
> >Can we change the "Example VendorSpecificCapabilities" to make it really 
> >obvious what is expected...right now I have servers returning:
> >http://sigma.openplans.org/geowebcache/service/wms?request=getcapabilities
> >><WMT_MS_Capabilities version="1.1.1" updateSequence="0">
> >>   <VendorSpecificCapabilities>
> >>     <TileSet><SRS>EPSG:4326</SRS><BoundingBox srs="EPSG:4326" 
> >>minx="-180.0" miny="-90.0" maxx="180.0" maxy="90.0" />
> >>        ....
> >>     </TileSet>
> >>   </VendorSpecificCapabilities>
> >></WMT_MS_Capabilities>
> >Which is not enough information for clients (ie uDig) to fetch Titles 
> >and Layer information. WMS-C is not a standalone server; it is an 
> >additional ability added to an existing WMS server.
> Hum, reality seems to think otherwise, both TileCache and GWC are
> born as standalone servers, they cannot serve non tiled requests.
> GWC can be embedded in GeoServer as a convenience, but it does not
> act as an extension to WMS.

Reality or not, the Capabilities were designed to be in addition to
standard WMS capabilties. The fact that TileCache doesn't do non-tiled
requests doesn't mean that the WMS information isn't neccesary: most of
the metadata was always supposed to be delivered by the 'traditional'
WMS GetCaps, and excluding it from your response is (imho) buggy.

(I don't *think* TileCache does that, but if it does, it should be

Christopher Schmidt

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