[Auscope-geosciml] CGI Value abomination
Bruce.Simons at dpi.vic.gov.au
Bruce.Simons at dpi.vic.gov.au
Wed Sep 2 00:21:26 EDT 2009
I like Rob's suggestion - at least the bit I understand - "This way no
client models actually need to change. The implementation of CGI_Value
using the old model is now an implementation choice, that can be
What does the rest mean? ie how do we actually do it?
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<Rob.Atkinson at csiro.au>
Sent by: auscope-geosciml-bounces at lists.arcs.org.au
02/09/2009 08:22 AM
Please respond to
auscope-geosciml at lists.arcs.org.au
<auscope-geosciml at lists.arcs.org.au>, <Oliver.Raymond at ga.gov.au>
Re: [Auscope-geosciml] CGI Value abomination
would it be possible to recast CGI_Value as a facade to an implementation
as a specialisation of ISO19146, and have a canonical implementation of
ISO19146 using a pre-defined set of service interfaces (SKOS maybe +
something with more ontological power?)
This way no client models actually need to change. The implementation of
CGI_Value using the old model is now an implementation choice, that can be
deprecated. New systems (with suitable deployment profiles) could demand
the canonical implementation.
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From: auscope-geosciml-bounces at lists.arcs.org.au
[mailto:auscope-geosciml-bounces at lists.arcs.org.au] On Behalf Of Simon Cox
Sent: Tuesday, 1 September 2009 5:10 PM
To: Oliver.Raymond at ga.gov.au
Cc: auscope-geosciml at lists.arcs.org.au
Subject: [Auscope-geosciml] CGI Value abomination
I have been grumbling about this for a while, and hope that it can be
addressed in the upcoming meeting in Quebec.
Way too many of the class attributes in GeoSciML use CGI_Value and its
I am fully aware of the history of when CGI_Value it was created (Ottawa,
2005) and its value (it allowed us to move forward on the bigger issues).
It also allowed a lazy UML design process, where for most atttributes the
type was set following a logic of just 'we can't really think about this
now but it'll be some kind of word/number'.
Now I think it is time to set it aside and move on.
My fundamental objections to the almost ubiquitous use of CGI_Value are
(i) it is hard to implement - it relies on XML Schema substitution groups
(ii) it is not compatible with any other domain schema
(iii) it allows data providers to be 'lazy' and create instances that are
not interoperable on arrival
(iv) it forces decisions required for data-fusion over to the client -
this is fundamentally what a standard encoding is supposed to avoid!
(v) it privileges a marginal GeoSciML use-case (transmission of field
data) at the expense of the dominant use-case (exchange of
quality-controlled archival data).
Most of the time, the client will refer to 'standard definitions' provided
in the GeoSciML concept schemes to translate the values provided into
standard forms anyway, so why not get the provider to do that rather than
It is the job of the GeoSciML design task group to actually make some
choices, fix the type of the basic class attributes, and then require that
service providers conform - make them make the choice about the 'best'
value for an attribute, don't shirk the job and push it back to the
Almost all CGI_Value should be replaced by
with just a few being
(c) Range (new type)
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