WMO Core Metadata Profile
Extensions UML models XML schemata Example XML instances Changes since interim release (June 2006) Missing items
CBS-Ext.(06) agreed version 1.0 of the WMO Core Profile of the ISO Metadata Standard.
This document presents the extensions to the ISO Metadata Standard.
1. Extensions
A number of extension points were identified:
1.1 Citation Date
The WMO community need to resolve creation / issue / publication times with a granularity finer than 1 day. Therefore, CI_Date is deemed insufficient.
However, CI_Date (from ISO 19115) is realised as gco:Date_PropertyType (from ISO 19139). gco:Date_PropertyType is implemented as a CHOICE between gco:Date and gco:DateTime, thus delivering the functionality required within the WMO community.
There is no need to extend CI_Date.
1.2 Controlled vocabularies
The WMO community employ numerous 'controlled vocabularies' to restrict the set of values used to describe information. Previously, it had been thought that it would be necessary to create 'Code Lists' (as described within ISO 19115 geographic information - metadata, clause B.5 Codelists and enumerations).
However, further analysis suggests that the MD_Keyword element can be used to reference external controlled vocabularies via the MD_Keyword.thesaurusName attribute.
The recommendation is that artifacts such as WMO volume WMO-No. 182 International Meteorology Vocabulary and WMO volume WMO-No. 49 Technical Regualtions be implemented as as Multilingual CodeList catalogues (CT_CodelistCatalogue, from ISO 19139 geographic information - metadata (XML schema implementation), clause which are cited via MD_Keyword.thesaurusName.
The proposed WMO_CommunityTopicCategoryCode, enabling fine-grained thematic description within the meteorological domain (weather observations, weather forecasts, meteorology, hydrology, climatology etc.), can also be implemented in this way: only a standard MD_Keyword element need be used rather than an employ a metadata extension.
1.3 Hierarchical keyword taxonomies
The WMO Community express the need to use 'hierarchical' keyword taxonomies - such as NASA's GCMD Science Keywords [http://gcmd.nasa.gov/Resources/valids//gcmd_parameters.html] - in order to describe geographic information.
To achieve this, the standard CharacterString element has been extended to add a delimiter (token) between 'levels' in the hierarchy.
The delimiter can be specified at the instance document level, but has default value = "|".
GCMD keyword:
EARTH SCIENCE > Atmosphere > Air Quality > Smog
XML serialisation:
<wmo:DelimetedString delimiter="|">EARTH SCIENCE | Atmosphere | Air Quality | Smog</gco:CharacterString>
1.4 Identification of datasets from simulations
Within the WMO community, ANALYSIS TIME is often used to differentiate between datasets from numerical simulations.
The analysis time is considered to be a time instant.
This extension provides an analysisTime attribute that can be used to identify a particular dataset.
1.5 Usage period constraints
Within the WMO community information atrifacts (particularly weather forecasts) are perishable; that is they are only valid for a fixed period of time after issue as another, potentially more accurate forecast is likely to have been issued.
In particular, aviation weather forecasts are valid for only a specific period as defined by the Internation Civil Aviation Authority (ICAO)
This extension enables one to specify the time period during which the dataset is valid. Outside this time period, the dataset must not be used for operational purposes.
2. UML models
UML is the canonical notation used in the ISO 19100 series of standards for Geographic Information developed by ISO/TC 211. However, UML provides a rich palette, and even within class- diagrams the UML elements may be combined in a variety of ways to represent similar functions. In order to restrict the variability, a strict "profile" of UML is used. This is defined primarily in ISO 19103, with some contextual clarification in ISO 19109, 19118 and 19136.
2.1 UML Model
"WMO Core Metadata Profile - Extensions" builds on the "HollowWorld" model developed within the SEEGrid community.
The primary resource is the "WMO Core Metadata Profile - Extensions.EAP" file, which is a UML template in "Enterprise Architect" format.
Enterprise Architect is a UML modelling interface from Sparx Systems http://www.sparxsystems.com.au.
A "read only" version of the software is available at no cost from http://www.sparxsystems.com.au/products/ea_downloads.html
The base "HollowWorldOM.EAP" (without WMO extensions) can be found here: https://www.seegrid.csiro.au/subversion/xmml/HollowWorld/
The WMO Core Profile Metadata Extensions can be found by browsing the 'Project View':
Model > HollowWorld > WMO Core Metadata Profile
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2.1.1 HollowWorld - a GML application schema template
A discussion concerning the application of HollowWorld can be found at the following link:
2.2 Model documentation
Model documentation (exported from Enterprise Architect) can be found at the following links; either as RTF or HTML
2.2.1 RTF documentation
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2.2.2 HTML documentation
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2.3 XMI export
The XML Metadata Interchange format allows a model from one tool to be exported (as XMI) and imported into another tool.
[Refer to wikipedia for more information: http://en.wikipedia.org/wiki/XMI]
"wmo_metadata_extensions.xmi" has been exported from "Enterprise Architect" UML modelling tool via the "XML Model Interchange" format; UML 1.3, XMI 1.0.
The model provided here is ONLY the WMO extensions to ISO19139. For a complete model (into which the WMO extensions can be imported) refer to https://www.seegrid.csiro.au/subversion/xmml/HollowWorld/
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2.3.1 XMI export for HollowWorld and ISO TC/211 packages
3. XML schemata
3.1 WMO Core Metadata Profile - Extensions
The extensions illustrated within the UML model have been serialized to W3C XML schema.
The serialisation is (believed to be) compliant with ISO 19139 'geographic information - metadata (xml schema implementation)' clause 8 'ecoding rules' and clause A.3 'conformance requirements - extensions'.
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3.2 ISO 19139
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3.3 resources for ISO 19139
Codelists etc.
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3.4 GML 3.1.1
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3.5 xlink 1.0.0
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4. Example XML instances
All example XML instances have been validated (as provided) with oXygen 7.2 XML editor [http://www.oxygenxml.com].
Note that external schema are referenced at source (i.e. http://www.isotc211.org/2005). The WMO extensions schema is referenced locally (../wmo/wmo_metadata_extensions.xsd) as it is yet to be published externally.
oXygen uses the java Xerces XML Parser from apache.
Due to issues regarding the 'clash' between GML 3.1.1 and ISO19139 (schema packages seem to be imported multiple times) the 'honour-all-schemaLocations' was turned OFF [Options > XML Parser > XML Parser Features > http://apache.org/xml/features/honour-all-schemaLocations]
For more details on Xerces, refer to:
The 'honour-all-schemaLocations' feature is discussed at:
4.1 'vanilla' ISO 19139 example
Vector Smart Map level 0 (VMAP0); from ISO 19139 'geographic information - metadata (xml schema implementation)' clause D.3
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4.2 WMO Core Metadata Profile examples
The examples included here are acknowledged as being incomplete.
The subject 'domain' of the examples are aviation forecasts: Terminal Aerodrome Forcasts (TAFs) as currently exchanged on the GTS.
The TAFs used within the examples are described in the following document:
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4.2.1 Rolling archive
ukmo.jedds.taf.xml and ukmo.jedds.metar.xml are supposed to represent a rolling ‘archive’ of TAFs & METARs (respectively) … global geospatial extent & including the last 3 days-worth of bulletins
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4.2.2 TAF bulletin "templates"
int.wmo.wis.taf.TTAAii.xml represent TEMPLATEs for TAF bulletins that are exchanged on the GTS … the idea is that these metadata records will be exposed on the WIS catalogue thus allowing users to subscribe to this bulletin for regular delivery
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4.2.3 Specific TAF bulletins
int.wmo.wis.taf.TTAAii.CCCC.ddHHMM.nnn.xml describe SPECIFIC instances of TAFs that are exchanged on the GTS … much bigger than the TAF bulletin itself, but we may need to pass standards-compliant metadata with the data if users request the information
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5. Changes since interim release (June 2006)
5.1 Schema packaging
The extensions are now packaged within a single XML schema document (wmo_metadata_extensions.xsd) for simplicity.
5.2 WMO_DelimitedString
  • changed name (from WMO_DelimetedString) to correct spelling mistake.
  • new mandatory isoType attribute (fixed value "CharacterString") indicating the ISO class which it extends from
Attribute delimiter:
  • changed name (from delimeter) to correct spelling mistake
  • now has default value "|"
5.3 WMO_SimulationDataIdentification
  • changed name (from WMO_SimulationIdentification) to improve semantics.
  • new mandatory isoType attribute (fixed value "MD_DataIdentification") indicating the ISO class which it extends from
5.4 WMO_UsagePeriodConstraints
  • new mandatory isoType attribute (fixed value "MD_Constraints") indicating the ISO class which it extends from
6. Missing items
  • There is no data dictionary included in this documentation, although information describing the extensions is provided here: model documentation
  • Metadata extension information (describing the extensions created for this WMO Profile) has not been created; refer to ISO 19115 'geographic information - metadata' clause A2.11 'metadata extension information' for more details
  • There is no mechanism in place to link a metadata record that describes a dataset to the service where the dataset can be accessed. The so-called 'service metadata' is out of scope for this release.