[Mapserver-users] getFeatureInfo on dynamic layer -emptyexception

[Frieso ter Haseborg]

Hi Daniel,

thanx a lot for the explanation of this MS-behaviour. So MS doesn't
cascade getFeatureInfo-requests. That brings me to another question: How
do I build a _cascading_ wms-server-architecture capable of
getFeatureInfo-requests? 

I'm not sure if I understood the handling of the
getWMSFeatureInfoURL()-method correctly, but I think this only helps me
on the client-side. What do I do with another WMS-server, which tries to
access the dynamic layers on a remote mapserver created by my
php-component?

So far, I didn't manage to get a working sample of a
getWMSFeatureInfoURL, so excuse my perhaps premature disbelief: What
would be the result of the getWMSFeatureInfoURL()-method? Wouldn't that
be an URL, where again a getFeatureInfo-request is launched against my
dynamic layer? The only way to solve this I can imagine so far, is to
create an URL which refers directly to a php, which processes a kind of
getFeatureInfo-operation and returns the desired data. Perhaps I've a
major misunderstanding of the underlying concept.

TIA,
 
Frieso ter Haseborg
- Software Development - 
 
--

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S&F Datentechnik GmbH&Co.KG 
Reimersstr. 41b 
26789 Leer, Germany


>-----Original Message-----
>From: Daniel Morissette [mailto:morissette at dmsolutions.ca]
>Sent: Wednesday, November 05, 2003 3:03 AM
>To: Frieso ter Haseborg
>Cc: mapserver-users at lists.gis.umn.edu
>Subject: Re: [Mapserver-users] getFeatureInfo on dynamic layer
>-emptyexception
>
>
>Frieso ter Haseborg wrote:
>> 
>> I want MS to call my php like this:
>> http://my.ip/kmvims/test4.php?version=1.1.0&request=GetMap. This part
>> works! 
>> 
>
>This works because MapServer is able to cascade GetMap requests...
>
>
>> When calling 
>> 
>http://my.ip/cgi-bin/mapserv.exe?map=../htdocs/kmvims/test.map&
>version=1
>> 
>.1.0&request=GetFeatureInfo&query_layers=wms&x=251&y=329&INFO_F
>ORMAT=tex
>> t/plain 
>> 
>> I want MS to call my php like this:
>> 
http://my.ip/kmvims/test4.php?version=1.1.0&request=GetFeatureInfo&query
> _layers=wms&x=251&y=329&INFO_FORMAT=text/plain 
> 
> So I could do the getFeatureInfo-processing in my php and just return
a
> plain text, html or whatever MS needs to process. But MS refuses to
call
> the php at all on doing a getFeatureInfo-req.
> 

... and this doesn't work because MapServer doesn't cascade 
GetFeatureInfo requests.  The main reason behind this is that the output

of GetFeatureInfo requests is not clearly defined by WMS so MapServer 
would no know what to expect from the remote server.

Instead MapScript offers a $layer->getWMSFeatureInfoURL() method that 
will return you the GetFeatureInfo url for a click at a specified 
location on a WMS layer and it's up to your client application (PHP 
script) to call this URL and try to make sense of the result.

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