[mapguide-internals] RFC39 - Ready For Review - "Add layer name toWMS GetFeatureInfo response"

[Zac Spitzer]

Has RFC 39 been implemented?

http://trac.osgeo.org/mapguide/ticket/225 is listed as closed

On Wed, Oct 10, 2007 at 5:32 AM, Thomas M. Tuerke <
thomas.m.tuerke at autodesk.com> wrote:

> The GFI request has historically been "weak" in terms of the information it
> provides... typically just human-readable content, with little
> machine-readable value.  My sense is that the drafters originally
> contemplated it for putting into a "popup" or status panel, but not for the
> client machine to do much with beyond that.
>
> >From the WMS 1.1.1 spec: (-->>emphasis mine<<--)
> The GetFeatureInfo operation is designed to provide clients of a WMS with
> more information about features in the pictures of maps that were returned
> by previous Map requests. -->>The canonical use case for GetFeatureInfo is
> that a user sees the response of a Map request and chooses a point on that
> map for which to obtain more information.<<-- The basic operation provides
> the ability for a client to specify which pixel is being asked about, which
> layer(s) should be investigated, and what format the information should be
> returned in. Because the WMS protocol is stateless, the GetFeatureInfo
> request indicates to the WMS what map the user is viewing by including most
> of the original GetMap request parameters (all but VERSION and REQUEST).
> From the spatial context information (BBOX, SRS, WIDTH, HEIGHT) in that
> GetMap request, along with the X,Y position the user chose, the WMS can
> (possibly) return additional information about that position. The behavior
> described above is geared toward the picture case. In the graphic element
> case, the semantics of GetFeatureInfo are less defined. -->>The intent is to
> gain experience with this version of the request and perhaps provide
> additional rigor in future versions of the specification.
>
> The actual semantics of how a WMS decides what to return more information
> about, or what exactly to return is left up to the WMS provider.<<--
>
> As such, we allowed the templates to define what GFI returns, based on the
> installation's knowledge of the information it can provide... (and with a
> wink and a nod that it's really just suitable for human eyes, unless
> somebody comes along with a more rigorous response type.)
>
> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org [mailto:
> mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Jason Birch
> Sent: Tuesday, October 09, 2007 10:09 AM
> To: MapGuide Internals Mail List
> Subject: RE: [mapguide-internals] RFC39 - Ready For Review - "Add layer
> name toWMS GetFeatureInfo response"
>
>
> Wow, just re-read the spec for GetFeatureInfo (even at 1.3), and am once
> again wondering why they even bothered to include it.  There is no way
> of reliably using the information returned from any server, without
> having a knowledge of that server's implementation.
>
> Since there is no guidance at all on what should be included in the
> response to this query, I'm OK with this workaround.  It doesn't seem
> "right" to bake application-specific logic into WMS, but it seems to be
> what the spec requires...
>
> I'm thinking that for this kind of application WFS would be a better
> approach anyway?  Not knowing anything about WFS, is there a way of
> redirecting WMS GetFeatureInfo to WFS resources?  Or using a WFS
> response to GetFeatureInfo (not sure if this problem exists in WFS as
> well, or if it's specifically constrained to single-layer access)?
>
> Jason
>
> -----Original Message-----
> From: Chris Claydon
> Subject: [mapguide-internals] RFC39 - Ready For Review - "Add layer name
> toWMS GetFeatureInfo response"
>
> MapGuide Open Source RFC 39 is now ready for review. It can be found at
> the following location:
>
> http://trac.osgeo.org/mapguide/wiki/MapGuideRfc39
>
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Zac Spitzer -
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