[OSGeo-Discuss] The OGC schema changes related to XLink

Adrian Custer acuster at gmail.com
Fri Jun 29 12:54:01 PDT 2012

Hey all,

As some of you are aware the Open Geospatial Consortium (OGC) has
adopted a policy to alter the XLink dependency in many of the XML
schemas maintained by the OGC and used for several Web Services and for
some GML. 

This situation arises because the OGC adopted their own 'stub' XLink
schema back before the W3C had published any official schema for XLink.
Now that there is an offical W3C schema, the OGC is attempting to
re-align all existing OGC schemas on those new XLink schemas. The FAQ
(see below), explains that they chose to consider these backwards
incompatible changes to be 'fixes' allowing for this approach
retroactively 'fixing' all the schemas to reference the official W3C XML
Schema. Since the 'fix' is backwards incompatible, that approach
surprised many of us. 

When the issue last came up, I took action to press for more explanation
from the OGC folk, since I am involved over there.

Carl Reed, the Chair of the Technical Committee at the OGC (where all
the standards work happens), has just released several documents related
to the transition. 

Back in April, Carl published a blog entry discussing the process:

He has now published two documents, a letter and a FAQ:

On Thu, 2012-06-28 at 16:33 -0400, creed at opengeospatial.org wrote:
> Dear OGC Members
> Based on final input from the TC and the PC concerning the transition
> of the OGC XLink schema to the W3C XLink 1.1 schema, I developed an 
> overview letter with updated information. Based on Member feedback, I 
> also wrote an XLink transition FAQ. The FAQ is a living document that 
> I can updated based on feedback and additional information.
> The letter is here:
> https://portal.opengeospatial.org/files/?artifact_id=49562
> and the FAQ is here:
> https://portal.opengeospatial.org/files/?artifact_id=49563
> We will stand up a twiki for community collaboration during the 
> transition period.
> Thanks and regards
> Carl Reed
> Technical Committee Chair

(Unfortunately these are both in the MS Office format .docx). 

Finally, the OGC has set up an email list for discussions related to the
Carl has assured me they will open the archives for public viewing so we
don't all have to sign up to see the tone and content of the

These documents are not totally satisfactory but are probably all we are
going to get on the subject. For instance, I do not understand the
impact on their certification process: all their certified services will
stop being compatible after the transition. 

So for those who are interested, there is ow a little more information
and a mailing list for contact and discussion.


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