[Mapserver-users] OGC WMS GetfeatureInfo - MapServer 4.2

[Daniel Morissette]

Julien, Heryk wrote:
> 
> So I'm passing the same information in two different parameters
> (Query_Layers and Layers)!
> In table 9 (The Parameters of a GetFeatureInfo Request p.40) of the OGC
> specs (http://www.opengis.org/docs/01-068r3.pdf) the layers param is not
> needed in a GetFeatureInfo request.
> 

A GetFeatureInfo is performed by clicking on a map produced using a 
GetMap call, so you need to indicate to the server which map you clicked 
on, that's why you need to carry the GetMap requests.

The parameters listed in table 9 are only those you need to add on top 
of the corresponding GetMap parameters. This is indicated, but maybe not 
clearly enough, in 7.3.1 page 39:

   "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)."

Of course LAYERS may be considered redundant in this context, but there 
may be contexts that I can't think of right now where it is useful, so 
instead of documenting a bunch of exceptions the spec just says: "start 
with the GetMap parameters, and add the GetFeatureInfo parameters on top."

Note that in QUERY_LAYERS you should only pass the layers you want to 
query, this will often be a subset of the LAYERS parameter.

HTH

Daniel
-- 
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  Daniel Morissette               dmorissette at dmsolutions.ca
  DM Solutions Group              http://www.dmsolutions.ca/
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