[Requests] RFC 37: Geoscience Australia comments on proposed O&M specification

Chris.Body@ga.gov.au Chris.Body at ga.gov.au
Thu Mar 8 00:00:27 EST 2007


PART A

 

 

1. Evaluator:

Geoscience Australia

PO Box 378

Canberra, ACT 2601

Australia

Contact details - Chris Body chris.body at ga.gov.au

 

2. Submission:

RFC No.37

OGC Document 05-087r4, Observations and Measurements

 

 

 

PART B

 

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1. Requirement: [1]

Consider alternatives to the use of Record and RecordDefinition within
ComplexObservation. 

Namely, alternatives that don't specify a content model in instance
documents/objects.

 

2. Implementation Specification Section number: [6.5.2 - Page 15 & XML
examples Page 119]

 

3. Criticality: [Major]

 

4. Comments/justifications for changes: [Comments]

Whilst the ComplexObservation appears useful as a way to support Observations
on multiple properties of a feature, its use of Record and RecordDefinition
is complex and hinders application and tool support.

Although Record and RecordType appear ratified as part of ISO 19103, strong
justification would seem necessary to offset the complexity of a nested
mechanism to define a content model.

The disadvantages of this approach are apparent in the XML encoding layer,
namely sacrifice of the ability to validate Record instances or otherwise use
XML "schema aware" technologies.

i.e. Tools need to be developed from scratch to support this content model.

We suggest consideration of alternative ways to achieve this binding.

For instance, use of domain schema components/classes that redefine a "view"
of the feature of interest (essentially a restriction pattern).

 

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1. Requirement: [2] 

Possible need to support more strongly typed CalulationProcedure/algorithm
type for machine readability.

 

2. Implementation Specification Section number: [4.2 - Page 39]

 

3. Criticality: [Minor]

 

4. Comments/justifications for changes: [Comments]

Within O&M, Procedure information is primarily descriptive, with some effort
made to support a more complex model for accuracy or error.

SensorML allows for more complex, strongly typed Processes/Detectors but
appears not to be a suitable model for general mathematical
algorithms/functions/processes.

The "CalculationProcedure" <<ObjectType>> on Page 38-39 models the algorithm
property as a CharacterString which limits its usefulness to description or
identification only.

Having stated this, it is also apparent that Procedure serves a primarily
descriptive role, and typically identifies canonical or out-of-band entities
via reference mechanisms.

 

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1. Requirement: [3] 

Update XML Schema in ANNEX D to correct minor inconsistencies with UML Class
Model.

 

2. Implementation Specification Section number: [Figure 1 & Figure 5]

 

3. Criticality: [Minor]

 

4. Comments/justifications for changes: [Comments]

Perhaps just a result of an update to the UML model without an updated
ShapeChange generated schema. For example is the listing for observation.xsd
appears to model the quality property with different multiplicity and type
than is shown in Figure 5. 

 

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1. Requirement: [4] 

Remove the use of the term 'determinant' as a synonym for observable

 

2. Implementation Specification Section number: [4.12, 4.23 Def. Page 6-7 and
used on Pages 1,4,6,7,25]

 

3. Criticality: [Minor]

 

4. Comments/justifications for changes: [Comments]

If the terms are truly synonymous then using only one should improve the
readability of the specification.

It is really only used in its own right on Page 25.

 

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1. Requirement: [5]

 

Add document reference from Clause 6.6 on Observation procedures to Annex C,
Clause 4.

 

2. Implementation Specification Section number: [6.6 - Page 18]

 

3. Criticality: [Minor]

 

4. Comments/justifications for changes: [Comments]

Clause 6.6 on Observation procedures might benefit from clarifying the
implication of Procedure being of type <<Union>>, namely that one or other of
ProcedureSystem or ProcedureEvent can be specified but not both.
Alternatively, just reference Annex C, Clause 4 from Clause 6.6 (where the
relationship is described as such in the last sentence of the clause).

 

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1. Requirement: [6]

Confirm the correct order of the words 'ultimate' and 'proximate' as used in
Clause 8.1, Paragraph 1, Sentence 5.

 

2. Implementation Specification Section number: [8.1 - Page 25]

 

3. Criticality: [Minor]

 

4. Comments/justifications for changes: [Comments]

The order of these terms appears back-to-front in this sentence?

  

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Chris Body

 

Information Standards Coordinator

Corporate Data and Web Unit

Information Services & Technology Branch

Geoscience Australia

Jerrabomberra Avenue

Symonston  ACT 2617

 

Tel: 61 (02) 62499328

Email: chris.body at ga.gov.au

 

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