[Tilecache] WMS (il)legal URLS

[Paul Ramsey]

Did you know that in order to create legal WMS client URLs you have to  
contravene the usual rules of URL construction? I bet you didn't.

Tilecache generates this URL

http://openmaps.gov.bc.ca/ecwp2/ecw_wms.dll?layers=REGIONAL_MOSAICS_BC_VANDERHOOF_XC500MM_UTM10_2006&styles=&service=WMS&width=256&format=image%2Fjpeg&request=GetMap&height=256&srs=EPSG%3A4326&version=1.1.1&bbox=-125.685975321%2C52.8956903062%2C-124.441343334%2C54.1403222933

Based on this configuration

[vanderhoof]
type=WMS
url=http://openmaps.gov.bc.ca/ecwp2/ecw_wms.dll?
extension=jpg
layers=BC_BC_BARKBEETLE_XC1M_BCALB_2004
srs=EPSG:4326
bbox 
= 
-125.68597532095629,52.895690306154634 
,-123.19671134658027,54.304065106304094

The "rules" of WMS client URL construction say that you don't encode  
the tokenizing characters (& = ?), just like normal, but there are  
also some special characters that you don't encode when they are used  
relative to particular parameters:

/ Separator between MIME type and subtype in format parameter value.
: Separator between Namespace and Identifier in SRS parameter value.
, Separator between individual values in list-oriented parameters.

Whoa! Crazyness! But that's the way the spec is written.
So the ":" in the SRS, shouldn't be encoded.
Nor should the "/" in the format.
And note that the "," in the layers and bbox parameters should not be  
encoded WHEN THEY ARE SEPARATORS.  This presumably allows european use  
of the comma as a decimal, and the use of commas in layer names, while  
still using commas as separators.

This is an issue for strict servers, like the one cited above.