[GeoSciML] GML-nil-1.0.doc

Steve Richard steve.richard at azgs.az.gov
Tue Aug 14 07:13:06 EDT 2012


Simon-

I think there needs to be some discussion/justification for the use of the
xlink:/http:{OGC nil} pattern replacing the gml:nil & nilReason pattern.
The assertion of a consistent xlink pattern for nil values seems like an
important part of the spec, but that is not made clear in the intro/scope
part of the doc.

 

Also that the presence of the 'nillableProperties' or
'notNillableProperties' appinfo element or some other flag is necessary to
indicate that the convention used for nil values is the xlink pattern as
opposed to the nil/nilreason pattern in a particular instance document.  The
validation of the nil patterns will require schematron, won't it-with some
rule that checks first for the flag indicating which nilabl pattern is used
(gml or the new ogc:nil).  

 

steve

 

From: geosciml-bounces+steve.richard=azgs.az.gov at lists.opengeospatial.org
[mailto:geosciml-bounces+steve.richard=azgs.az.gov at lists.opengeospatial.org]
On Behalf Of Simon.Cox at csiro.au
Sent: Monday, August 13, 2012 5:28 PM
To: geosciml at lists.opengeospatial.org
Subject: Re: [GeoSciML] [ExternalEmail] Re: FW: Added requirement on
consuming application to GML-nil-1.0.doc

 

Oh - I should probably point out the consequences for GeoSciML. 

 

This work was motivated by the discussion in June about the difficulty of
using SamplingCurve as the basis for the GeoSciML Borehole feature type. 

The issue was that SamplingCurve and the other SpatialSamplingFeature
features have a mandatory 'shape' property which is not nillable in the
standard OMXML implementation. I pointed out that we (the GeoSciML
community) had in the past used a convention whereby the xlink:href
attribute could carry a nil URI to get the same effect. Clemens pointed out
a few issues with that interpretation, which this specification tried to
deal with. 

 

Primarily, it describes the approach formally so we all know what is going
on, and can also point external users to a document that explains it. 

It is constructed as a new specification, with 'modular' requirements and
conformance classes relating to four standardization targets: 

-        The UML model

-        The XML Schema

-        XML instance documents

-        Consuming applications

The 'conformance class' approach means that we are not forcing the issue for
anyone - you have to sign up to the spec before you would be expected to
satisfy the requirements. If the spec proves useful, then perhaps at some
future date it would be rolled into GML as optional conformance classes, but
this is not necessary for it to be useful to any community that chooses to
adopt it. 

 

For GeoSciML AFAICT it requires three changes

 

(i)                Add voidableProperties="true" as a tagged value to each
<<applicationSchema>> package

(ii)              Add <appinfo>nillableProperties</appinfo> to the
all-components XML Schema document for each namespace

(iii)             Increment the GeoSciML version number to 3.1 (its backward
compatible for document instances, so only minor version required). 

 

CSIRO, Landcare and BGS will propose this as an OGC RFC. If anyone else
wants to join as a sponsor, then you are welcome. 

I don't expect much objection - it is tightly scoped, completely optional,
but useful. 

It could get through the OGC process in a matter of months. 

 

Simon

 

From: geosciml-bounces+simon.cox=csiro.au at lists.opengeospatial.org
[mailto:geosciml-bounces+simon.cox=csiro.au at lists.opengeospatial.org] On
Behalf Of Simon.Cox at csiro.au
Sent: Monday, 13 August 2012 12:44 PM
To: geosciml at lists.opengeospatial.org
Subject: [ExternalEmail] Re: [GeoSciML] FW: Added requirement on consuming
application to GML-nil-1.0.doc

 

Here is the up-to-date version, with some contributions from Alistair. 

 

From: geosciml-bounces+simon.cox=csiro.au at lists.opengeospatial.org
[mailto:geosciml-bounces+simon.cox=csiro.au at lists.opengeospatial.org] On
Behalf Of Duffy, Tim
Sent: Monday, 13 August 2012 6:57 AM
To: geosciml at lists.opengeospatial.org
Subject: [GeoSciML] FW: Added requirement on consuming application to
GML-nil-1.0.doc

 

'nil' document for discussion by geosciml group later this week (Simon said
last week he wanted this sent to the wider group in time for this.

regards

Tim

 

  _____  

From: Simon.Cox at csiro.au [Simon.Cox at csiro.au]
Sent: 31 July 2012 02:53
To: RitchieA at landcareresearch.co.nz; steve.richard at AZGS.AZ.Gov; Laxton, John
L.; Duffy, Tim; Bruce.Simons at csiro.au
Subject: Added requirement on consuming application to GML-nil-1.0.doc

On reflection, I realized that it was incomplete without requirements on
consuming applications, so I added a clause. 

 

Would be grateful of any feedback (thanks Bruce). 

 

Simon

Attached is now essentially complete. 

Any interest in co-sponsoring this as an RFC submission to OGC? 

 

Simon


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