[mapserver-users] MapScript WMS request

[Fawcett, David (MPCA)]

Puneet, 

As far as I know, OpenLayers still has support for a layer based on MapServer CGI.  Because MapServer can also serve up WMS well, this layer type isn't necessarily recommended or as well supported.  

http://dev.openlayers.org/docs/files/OpenLayers/Layer/MapServer-js.html

David.

-----Original Message-----
From: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Mr. Puneet Kishor
Sent: Thursday, September 08, 2011 9:32 PM
To: Daniel Morissette
Cc: mapserver-users at lists.osgeo.org
Subject: Re: [mapserver-users] MapScript WMS request


On Sep 8, 2011, at 8:28 PM, Daniel Morissette wrote:

> On 11-09-08 09:02 PM, Mr. Puneet Kishor wrote:
>> 
>> On Sep 8, 2011, at 7:43 PM, Daniel Morissette wrote:
>>> 
>>> Maybe call $map->save("/tmp/my.map") in your script after the map and layer have been populated and paste the result... that may give us a hint...
>>> 
>> 
>> wow! this is a super-awesome debugging technique. I have sent you the map file off list to not pollute the entire list serve.
>> 
> 
> I was able to reproduce the issue with the copy of the mapfile you sent off-list.
> 
> It turns out that mappostgis.c's msPostGISLayerGetExtent() is hardcoded to always return
> 
> {minx = -25000000, miny = -25000000, maxx = 25000000, maxy = 25000000}
> 
> ...and then it returns MS_SUCCESS.
> 
> I think this function should either be left unimplemented (this way MapServer would fallback on other mechanisms), or return MS_FAILURE to indicate to the calling code that it didn't do anything useful.
> 
> A quick search indicates an open ticket about the issue:
> 
> http://trac.osgeo.org/mapserver/ticket/3585
> 
> You could bump the ticket and hope someone works on it at the FOSS4G code sprint next week.
> 
> The short term fix for you would be to set the "ows_extent" metadata in your layer:
> 
>    METADATA
>      "ows_extent" "-180 -90 180 90"
>   ...
>    END
> 


Thanks Daniel. I will bump the ticket. For now, see below --

Using the "my.map" file I sent you, with no further modifications to it, I am able to successfully get an image back via [http://localhost.local/cgi-bin/gmna?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&BBOX=-180,-90,180,90&SRS=EPSG:4326&WIDTH=1200&HEIGHT=600&LAYERS=gmna&STYLES=&FORMAT=image/png&TRANSPARENT=true]

Note, no further modifications is required, that is, not even the "ows_extent" "-180 -90 180 90" bit in the layer METADATA. and I still get a good image.


However, if I use the following program to access the same map file, I get the spurious "minx = -25000000, miny = -25000000, maxx = 25000000, maxy = 25000000" in the GetCapabilities.

Finally, if I add the "ows_extent" "-180 -90 180 90" line in the layer METADATA in the "my.map" file, the GetCapabilities returns the correct bounds now, however, the image is still blank.

	#!/opt/local/bin/perl
	
	use strict;
	use mapscript;
	
	my $wms = new mapscript::OWSRequest();
	$wms->setParameter("SERVICE", "WMS" );
	$wms->setParameter("VERSION", "1.1.1" );
	$wms->setParameter("REQUEST", "GetMap" );
	$wms->setParameter("BBOX", "-180,-90,180,90" );
	$wms->setParameter("LAYERS", "gmna");
	$wms->setParameter("SRS", "EPSG:4326");
	$wms->setParameter("WIDTH", "1200");
	$wms->setParameter("HEIGHT", "600");
	$wms->setParameter("FORMAT", "image/png");
	$wms->setParameter("TRANSPARENT", "true");
	
	my $map = new mapscript::mapObj("/Users/punkish/Sites/test/mapscript/my.map");
	
	if(!$map) {
		warn "New mapObj() error: $mapscript::ms_error->{message}\n";
	}
	
	my $io = mapscript::msIO_installStdoutToBuffer();
	my $dispatch_out = $map->OWSDispatch( $wms );
	printf "%s\n", mapscript::msIO_getStdoutBufferString();

I have now spent an enormous amount of time on this, and for now, I have to move on. This is just not working out. Maybe I will try some other technique, perhaps this mode=tile to see if I can get MapServer powered maps in my apps.

Thanks much for your help. If you (or anyone else) can come up with a bright idea, I will be happy to try it.

Puneet.

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