[postgis-users] RE: [postgis-devel] GML output

Martin Daly Martin.Daly at cadcorp.com
Fri Sep 24 23:36:25 PDT 2004


Darko,
 
I did not say that the prefix was the namespace, I merely repeated your description of it as the "namespace prefix".
 
While it is true that GML 2 has D-IS status, it is also true that the WFS specification normatively references GML 2, and mandates its use as a returned format for the GetFeatures request.  Until such time as a new WFS spec is adopted, AND all implementations of WFS servers are brought up to date, AND all installations of those server implementations are upgraded, AND all WFS clients are brought up to date, AND all installations of those clients are upgraded, GML 2 is very much alive.
 
Regards,
Martin

	-----Original Message----- 
	From: Darko Androsevic [mailto:dandrosevic at galdosinc.com] 
	Sent: Fri 24/09/2004 17:34 
	To: Martin Daly; 'PostGIS Users Discussion' 
	Cc: 'Frank Warmerdam'; 'PostGIS Development Discussion'; 'Paul Ramsey' 
	Subject: RE: [postgis-users] RE: [postgis-devel] GML output
	
	

	Martin, 

	The prefix is NOT the namespace. The prefix is arbitrary. What counts is the URI. The use of prefix gml: is only convention and is  meaningless without the namespace binding. The binding is declared with xmlns attribute.

	See the "Namspaces in XML (World Wide Web Consortium 14-January-1999)": 
	http://www.w3.org/TR/REC-xml-names/ 

	Regarding 'prefixes', see section "3. Qualified Names", the very last 
	paragraph, reproduced below: 

	"Note that the prefix functions only as a placeholder for a namespace name. 
	Applications should use the namespace name, not the prefix, in constructing 
	names whose scope extends beyond the containing document" 




	GML2.x has been removed from the list of OGC specs 
	http://www.opengeospatial.org/specs/?page=specs 
	Its status is D-IS (Deprecated Implementation Specification). Given this, all future development should be based on GML3.x.


	Thanks, 
	Darko 



	-----Original Message----- 
	From: Martin Daly [mailto:Martin.Daly at cadcorp.com] 
	Sent: Friday, September 24, 2004 1:29 AM 
	To: Darko Androsevic; PostGIS Users Discussion 
	Cc: Frank Warmerdam; PostGIS Development Discussion; Paul Ramsey 
	Subject: RE: [postgis-users] RE: [postgis-devel] GML output 


	Darko, 

	> The namespace prefix is arbitrary--it could be "tns". What's 
	> essential is that the prefix is bound to the correct namespace: 
	> 
	> <tns:Polygon xmlns:tns="http://www.opengis.net/gml"> 
	> ... 
	> </tns:Polygon> 

	As I said originally "There are all sorts of ways to cope with 
	namespaces".  However, the AsGML() function works in isolation, only 
	producing the geometry property of a feature.  It has no context within 
	which to work.  Using the "gml:" namespace prefix removes the need for 
	an extra parameter, and probably improves interoperability. 

	> GML 2.x is history. 

	Your organisation is entitled to an opinion, but that doesn't make it 
	the truth. 

	Regards, 
	Martin 

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