Open Geospatial Consortium
OGC Document 08-xxx
CR-Form-v3
CHANGE REQUEST
GML CR ?
rev-
Current version:3.2.1
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on using this form, see bottom of this page or look at the pop-up text over the symbols.Proposed change affects: AS Imp Spec X Best Practices Paper Other
Title: GML 3.2.1 change request - Generalisation of CityGML extension mechanism
Source: Nicolas Lesage
Work item code: Date: 2008-09-18
Category: B
Use one of the following categories: F (Critical correction)
A (corresponds to a correction in an earlier release) B (Addition of feature),
C (Functional modification of feature) D (Editorial modification)
Reason for change: Application Domain Extensions (ADE) defined in CityGML (see clauses 6.12, 10.11, Annex G of OGC 08-007-r1) propose an extension mechanism which enables the addition of application specific properties (e.g. pollution statistics) to feature types (e.g. Building) without deriving a new feature type. This mechanism seems particularly useful when the application specific properties don’t change the intrinsic nature of the feature type (e.g., properties attached to building in order to simulate the immission of Noise, information related the state of geographic features for military application, …). This requirement is not limited to the CityGML Application Schema and may be applicable to any application schema. It is also understood that the use of this extension mechanism to add intrinsic properties of feature types could lead to a lack of interoperability. There is consequently a need to clearly border the intended use of this extension mechanism.
OGC 08-xxx
Summary of change: Different level of changes can be envisioned and are proposed to the GML 3.3 SWG for further discussion:
1. the minimal change is to clearly document this extension mechanism and its use so that the applications can be aware of it.
2. addition of an abstract global element
AbstractGenericApplicationProperty of type xs:anyType to be added in the application schemas to support the extension mechanism;
3. addition of a unbounded reference to this global element to
gml:AbstractFeatureType to enable this extension mechanism for any feature type or alternatively create a
gml:AbstractExtendableFeatureType deriving from
gml:AbstractfeatureType and supporting this unbounded reference to this global element.
Consequences if
not approved:
Emergence of multiple solutions handling the requirement leading to a lack of interoperability
Clauses affected: 9.3
Other specs X Other core specifications CityGML
Affected: Abstract specifications
Best Practices Papers
Supporting Doc.
Other comments:
Status
Disposition
