Page 1 A Proposal for a Reference Implementation of the WMO Core Metadata Profile based on...

A Proposal for a Reference Implementation of the WMO Core Metadata Profile based on

ISO-19115/19139

3rd May 2006

byJeremy Tandy, UK Met Office

Jürgen Seib, Deutscher WetterdienstMichael Burek, National Center for Atmospheric Research

A revised WMO Core Metadata Profile

WMO Core Metadata Profile … ISO 19115 compliant?

(also note that the standard itself has undergone some revision: ISO 19115:2003/Cor. 1:2006)

Motivation

version 0.2 is NOT compliant to ISO 19115XML schemas of version 0.2 are ‘bespoke’ UML model for WMO extensions does NOT exist

ISO 19115 compliance

WMO Core Profile v0.2 breaks the extension rules defined in ISO19115 Annex C

WMO encoding does not match ISO 19115 Changes to ISO 19115 (extensions) not in WMO-

governed namespace Examples:

Cardinality restricted Optional attributes removed … and much worse … (DQ_DataQuality)

Further issues were noted in the WMO IPET-MI report prepared by Clemens Portele

A revised WMO Core Metadata Profile

Characteristics of WMO metadata documentssimplehuman readable (optionally) self-contained; i.e. the metadata record

*should* be able to be expressed as a single document

multilingualXML-validity should imply semantic correctness ISO 19115 compliant ‘community profile’

ISO 19115 - Extensions

How do we create an ISO 19115 compliant metadata profile?

Guidance: ISO 19115 Annex C: Metadata extensions and

profiles ISO 19115 Annex F: Metadata extension

methodology

In order to ensure interoperability beyond the community where the extensions are implemented:

a) You must document the extension via the ‘extension metadata’ described in ISO 19115, and

b) Add an isoType attribute to the class indicating which ISO 19115 class was sub-classed

ISO 19115 Clause C.2: Types of extensions

adding a new metadata sectioncreating a new metadata code list to replace the

domain of an existing metadata element that has “free text” listed as its domain value

creating new metadata code list elements (expanding a code list)

adding a new metadata elementadding a new metadata entity imposing a more stringent obligation on an existing

metadata element imposing a more restrictive domain on an existing

metadata element

ISO 19115 Clause C.4: Rules for creating an extension

the name, definition or data type of an existing element can not be changed

a new element may include extended and existing metadata elements as components

metadata elements can be more stringent domains can be more restrictive the use of domain values can be restrictedcode lists of type «CodeList» can be expandedan extension shall not permit anything not allowed by

the standard

Rules for creating a profile

check registered profilesadhere to the rules for defining an extensionA profile shall include:

the core metadata all mandatory metadata elements all conditional metadata elements, if the dataset meets the

condition

use UML diagrams to describe a profile

use your own namespace

publish the profile

WMO namespace

namespace: collection of names, identified by an URI reference

is needed for extensionsXML schemas of WMO extensions should reside in the http://www.wmo.int/metadata/2006 namespace

xmlns:wmo = “http://www.wmo.int/metadata/2006”

So where do we go from WMO Core v0.2?

1. From the extension rules it’s clear that WMO Core v0.2 has problems

2. Furthermore, even *before* we extend ISO 19115 we need to identify an XML encoding of the content model

ISO 19115 is an ‘abstract specification’ …

IT specifies what information is required but not how to encode it

We developed our own XML encoding of ISO 19115 – as did many others

Interoperability is impaired by having numerous inconsistent encodings of ISO 19115 …

The ISO standard 19139

XML schema implementation for ISO 19115provides a common specification for describing,

validating and exchanging metadatadefines implementation guidelines for general-purpose

metadata includes XML schema implementations of other ISO

191xx series (including ISO 19136 / GML) according to ISO 19118 ‘Geographic Information – Encoding’

fulfils 99% of the needs for a WMO metadata standard

WMO metadata profile – key elements

Whilst ISO 19139 resolves a ‘large proportion’ (99%?) of metadata-related concerns from the WMO community … there are still a number of outstanding elements worthy of discussion:

1. Time2. Internationalisation / multilingual support3. Codelists and keywords4. Service metadata5. Catalogues – incl. Feature Catalogues

The future?

Whilst it is recommended that we adopt ISO 19139 as the ‘default’ encoding for WMO Core metadata …

We must ensure that WMO Core is fit for purpose within the WMO community –

where the existing ISO standard information models and encodings are not appropriate we should *adapt* them to our needs (e.g. ISO 19111 and parametric spatial referencing systems)

The ISO standards are still in flux; so long as we *engage* with ISO/TC 211 we can adapt the standards to suit WMO

This ‘profile’ is a *big* step forward, but it should not be considered a final version … it will continue to evolve

ISO 19118 Geographic Information - Encoding

ISO 19118 “Geographic information – Encoding” specifies rules for encoding geographic information … i.e. converting from the UML model to XML schema

ISO 19139 Clause 8 presents a good ‘summary’ in relation to encoding the ISO 19115 information model

ISO 19139 – Encoding summary (1)

Each UML class is encoded into 3 XML constructs:

1. XML Class Type (XCT) describing the content (attributes) of the UML class

2. XML Class Global Element (XCGE) ensuring the class has global visibility within the XML schema

for ‘import’ etc.

3. XML Class Property Type containment of a class is managed through the XML Class

Property Type of it’s data type, enabling both “by Value” and “by Ref” implementations of content

Note: when an XCT is of xs:simpleType, “by Ref” is not permitted

ISO 19139 – Encoding summary (2)

Naming conventions: UML class » Class1 XCT » Class1_Type XCGE » Class1 XCPT » Class1_PropertyType

Special case encodings: Abstract classes Inheritance and sub-classes

Note: to achieve interoperability only ‘extension’ sub-classing (i.e. adding attributes) is permitted – restriction and multiple inheritance are not allowed

Enumerations Codelists Unions

Polymorphism and substitution groups (1)

Polymorphism: the ability to assume different forms Example:

[CI_ResponsibleParty] » individualName [CharacterString] could be specialized such that ‘name’ is compartmentalized into first and last names

Polymorphism provides communities with a mechanism to better refine metadata to meet organizational need

individualName is extended within a ‘community’ namespace … whilst still utilizing ISO 19139 schemas (gmd namespace), and still providing usable & understandable instance documents

In OO, the specialized class “is a” type of the general class; e.g. a dog “is a” type of animal

Polymorphism and substitution groups (2)

The “is a” relationship implies semantic consistency & substitutability

ISO 19118 *only* permits simple (extension-only) sub-classing / specialization

ISO 19139 allows polymorphism primarily though the _PropertyType encodings; e.g.

gmd:PT_FreeText_PropertyType is substituted for the more general gco:CharacterString_PropertyType for multi-lingual support

Need to inform the XML parser of the substitution:

a) via a substitutionGroup directive in the schema, OR

b) via a xsi:type directive in the instance document

GML pattern: by-value or by-reference (1)

GML properties are defined such that the ‘content’ can be referenced EITHER

‘by-value’ within the scope of the containing XML element, OR ‘by-ref’ (xlink) to an instance of the content residing elsewhere;

either within the document or external

<xs:attributeGroup name="ObjectReference"> <xs:attributeGroup ref="xlink:simpleLink"/> <xs:attribute name="uuidref" type="xs:string"/></xs:attributeGroup>

<xs:attribute name="nilReason" type="gml:NullType"/>

<xs:complexType name="ObjectReference_PropertyType"> <xs:sequence/> <xs:attributeGroup ref="gco:ObjectReference"/> <xs:attribute ref="gco:nilReason"/></xs:complexType>

GML pattern: by-value or by-reference (2)

Example - from an “observations & measures” GML instance

<om:location xlink:href="#ot2p"/>

<om:observedProperty xlink:href="urn:x-ogc:def:phenomenon:OGC:Species"/>

<om:featureOfInterest>

<om:Station gml:id="ot2s">

<gml:name>8903</gml:name>

<om:position>

…

</om:position>

</om:Station>

</om:featureOfInterest>

by-reference

by-value

«xlink» semantics

<attributeGroup name="simpleLink"> <attribute name="type" type="string" fixed="simple"

form="qualified"/> <attribute ref="xlink:href" use="optional"/> <attribute ref="xlink:role" use="optional"/> <attribute ref="xlink:arcrole" use="optional"/> <attribute ref="xlink:title" use="optional"/> <attribute ref="xlink:show" use="optional"/> <attribute ref="xlink:actuate" use="optional"/></attributeGroup>

How should parsers interpret xlink? XML validation will *only* check the grammar of the xlink

statement xlink has ‘deferred binding’ semantics …

GML pattern: object-type-object-type ‘striping’

object

object

object

object

type

type

type

type

object

object

object

object

<om:location xlink:href="#ot2p"/>

<om:observedProperty xlink:href="urn:x-ogc:def:phenomenon:OGC:Species"/>

<om:featureOfInterest>

<om:Station gml:id="ot2s">

<gml:name>8903</gml:name>

<om:position>

<gml:Point gml:id="ot2p">

<gml:pos srsName="urn:x-ogc:def:crs:EPSG:6.3:62836405">

-30.7025065 134.1997256

</gml:pos>

</gml:Point>

</om:position>

</om:Station>

</om:featureOfInterest>

Interoperability outside WMO community

Document withoutWMO extensions

Document withWMO extensions

XSL Transformation

Users outside WMO community will (probably) NOT understand WMO extensions …

Need to ‘remove’ them???

Open Issues

Worked examples & implementation test-bed Finalize extensions

which are required? Time, ServiceIdentification etc.

encode as ISO 19118-compliant XML schema ISO 19115 / 19139 have a multitude of options for describing

information … which makes writing parsing applications complex

do we need to *restrict* WMO Core metadata? ISO/TC 211 & OGC community peer review

Thank you

© Crown copyright 2006 Page 27

Explanation of times for observations and simulations

Encoding in ISO 19115 / 19139 metadata

April 2006


Times relevant to a observations… a single observation …

even

tTim

e (t e

)eventTime encoded in ‘Observations & Measures’ as:

<om:Observation gml:id="obsTest1">…<om:time>

<gml:TimeInstant gml:id="ot1t"><gml:timePosition>2005-01-11T16:22:25.00</gml:timePosition>

</gml:TimeInstant></om:time>…

</om:Observation>

eventTime encoded in ‘Observations & Measures’ as:

<om:Observation gml:id="obsTest1">…<om:time>

<gml:TimeInstant gml:id="ot1t"><gml:timePosition>2005-01-11T16:22:25.00</gml:timePosition>

</gml:TimeInstant></om:time>…

</om:Observation>

Time at which the observation ‘event’ occurred (from om:Event)

(Often referred to as “validTime” within GML schemas)

issu

eTim

e (t i)

Time at which the observation was published / issued …

allowing for amendments to a previously published observation(we need to extend O&M for this)

real time axis (t)

Time in the “real world”Default temporal reference system:

ISO-8601 (Gregorian calendar)

ObservationObservation


Times relevant to a observations… what about accumulations? …

even

tTim

e (t e

)

time interval

Time interval relative to the observation time for calculating accumulations, averages etc.

An ‘instantaneous’ observation is conceptually simple; e.g. measuring temperature at a specific instant in time

However, what about accumulations (or averages etc.) … e.g. measuring a 3-hr average temperature? We assert that you can’t evaluate the average until the end of the 3-hr period.

We assert that the time interval is a property of the measured phenomena (a 3-hr average) & the eventTime (te) of observation occurs at the end of the time interval.

An ‘instantaneous’ observation is conceptually simple; e.g. measuring temperature at a specific instant in time

However, what about accumulations (or averages etc.) … e.g. measuring a 3-hr average temperature? We assert that you can’t evaluate the average until the end of the 3-hr period.

We assert that the time interval is a property of the measured phenomena (a 3-hr average) & the eventTime (te) of observation occurs at the end of the time interval.

issu

eTim

e (t i)

real time axis (t)


Times relevant to a observations… what about maxima & minima? …

even

tTim

e (t e

)

time interval

The primary observation (in this example) is the maximum temperature during a time interval.The maximum temperature cannot be evaluated until the end of the time interval.We assert that the time interval is a property of the measured phenomena (a daily

maximum) & the eventTime (te) time of observation occurs at the end of the time interval.

In many cases, the exact instance when the maximum temperature occurred cannot be determined. However, automated weather stations now offer near-continuous measurement & can record the time instant that an event (i.e. the maximum temperature) occurred.

We assert that the maximum temperature ‘event’ can be modelled as a related observation.

The primary observation (in this example) is the maximum temperature during a time interval.The maximum temperature cannot be evaluated until the end of the time interval.We assert that the time interval is a property of the measured phenomena (a daily

maximum) & the eventTime (te) time of observation occurs at the end of the time interval.

In many cases, the exact instance when the maximum temperature occurred cannot be determined. However, automated weather stations now offer near-continuous measurement & can record the time instant that an event (i.e. the maximum temperature) occurred.

We assert that the maximum temperature ‘event’ can be modelled as a related observation.

real time axis (t)

xTemperature fluctuation during time interval

Time instant at which the maximum temperature occurs

during the time intervalRelated observation:

temperature recorded at time instant

Related observation:temperature recorded at

time instant Primary observation:Maximum temperature

recorded during time interval

Primary observation:Maximum temperature

recorded during time interval


Times relevant to a observations… what about collections of obs? …

even

tTim

e (t e

)

collectionPeriod is the time interval bounding all discrete observations within the collection

(note: this would probably be encoded as an element of the spatio-temporal bounding box for the collection)

collectionPeriod is the time interval bounding all discrete observations within the collection

(note: this would probably be encoded as an element of the spatio-temporal bounding box for the collection)

colle

ctio

nPer

iod

real time axis (t)


Which time values are needed in observation feature types?

eventTime (te)Time at which the observation

event occurred

time interval(for calculating accumulations,

averages, max/min etc.)

part of the ‘phenomenon’ definition

Not valid:

collectionPeriodTime interval bounding all

discrete observations within the collection

(where appropriate)

Time properties:

issueTime (ti)Time at which the observation was published … allowing for

amendments


cd Time properties

Metadata entity set information::MD_Metadata

+ characterSet: MD_CharacterSetCode = "utf8"+ contact: CI_ResponsibleParty+ dataSet: CharacterString+ dateStamp: Date+ fi leIdentifier: CharacterString+ hierarchyLevel: MD_ScopeCode = "dataset"+ hierarchyLevelName: CharacterString+ language: CharacterString+ metadataStandardName: CharacterString+ metadataStandardVersion: CharacterString+ parentIdentifier: CharacterString

«Abstract»Identification information::

MD_Identification

+ abstract: CharacterString+ citation: CI_Citation+ credit: CharacterString+ pointOfContact: CI_ResponsibleParty+ purpose: CharacterString+ status: MD_ProgressCode

«DataObject»Citation and responsible party information::

CI_Citation

+ alternateTitle: CharacterString+ citedResponsibleParty: CI_ResponsibleParty+ collectiveTitle: CharacterString+ date: CI_Date+ edition: CharacterString+ editionDate: Date+ identifier: MD_Identifier+ ISBN: CharacterString+ ISSN: CharacterString+ otherCitationDetails: CharacterString+ presentationForm: CI_PresentationFormCode+ series: CI_Series+ title: CharacterString

«DataObject»Citation and responsible party

information::CI_Date

+ date: Date+ dateType: CI_DateTypeCode

«CodeList»Citation and responsible

party information::CI_DateTypeCode

+ creation+ publication+ revision

Identification information::MD_DataIdentification

+ characterSet: MD_CharacterSetCode = "utf8"+ environmentDescription: CharacterString+ extent: EX_Extent+ language: CharacterString+ spatialRepresentationType: MD_SpatialRepresentationTypeCode+ spatialResolution: MD_Resolution+ supplementalInformation: CharacterString+ topicCategory: MD_TopicCategoryCode

Extent information::EX_TemporalExtent

+ extent: TM_Primitive

«DataObject»Extent information::EX_Extent

+ description: CharacterString

+temporalElement 0..*

+identificationInfo 1..*

Time metadata in ISO 19115 (1)


cd TM_Primitiv e

Temporal Objects::

TM_Primitiv e

Temporal Objects::TM_Instant

Temporal Objects::TM_Period

Temporal Objects::TM_GeometricPrimitiv e

+end

1

+endedBy

0..*

+begin

1

+begunBy

0..*

Time metadata in ISO 19115 (2)


Encoding eventTime in ISO 19115 & ISO 19139

For a single observation, or a collection of observations with a common eventTime (te) …

metadata [MD_Metadata] »

identificationInfo [MD_DataIdentification] »

extent [EX_Extent] »

temporalElement [EX_TemporalExtent] »

extent [TM_Instant]

For a single observation, or a collection of observations with a common eventTime (te) …

metadata [MD_Metadata] »

identificationInfo [MD_DataIdentification] »

extent [EX_Extent] »

temporalElement [EX_TemporalExtent] »

extent [TM_Instant]

<MD_Metadata> <identificationInfo> <MD_DataIdentification> <extent> <EX_Extent> <temporalElement> <EX_TemporalExtent> <extent> <gml:TimeInstant> <gml:timePosition> 2005-01-11T16:22:25.00 </gml:timePosition> </gml:TimeInstant> </extent> </EX_TemporalExtent> </temporalElement> </EX_Extent> </extent> </MD_DataIdentification> </identificationInfo></MD_Metadata>

<MD_Metadata> <identificationInfo> <MD_DataIdentification> <extent> <EX_Extent> <temporalElement> <EX_TemporalExtent> <extent> <gml:TimeInstant> <gml:timePosition> 2005-01-11T16:22:25.00 </gml:timePosition> </gml:TimeInstant> </extent> </EX_TemporalExtent> </temporalElement> </EX_Extent> </extent> </MD_DataIdentification> </identificationInfo></MD_Metadata>


Encoding collectionPeriod in ISO 19115 & ISO 19139

For a collection of observations spanning multiple times, collectionPeriod …

metadata [MD_Metadata] » identificationInfo [MD_DataIdentification] » extent [EX_Extent] » temporalElement [EX_TemporalExtent] » extent [TM_Period]

For a collection of observations spanning multiple times, collectionPeriod …

metadata [MD_Metadata] » identificationInfo [MD_DataIdentification] » extent [EX_Extent] » temporalElement [EX_TemporalExtent] » extent [TM_Period]

<MD_Metadata> <identificationInfo> <MD_DataIdentification> <extent> <EX_Extent> <temporalElement> <EX_TemporalExtent> <extent> <gml:TimePeriod> <gml:beginPosition> 2006-01-11T16:22:25.00 </gml:beginPosition> <gml:endPosition> 2006-01-12T16:22:25.00 </gml:endPosition> </gml:TimePeriod> </extent> </EX_TemporalExtent> </temporalElement> </EX_Extent> </extent> </MD_DataIdentification> </identificationInfo></MD_Metadata>

<MD_Metadata> <identificationInfo> <MD_DataIdentification> <extent> <EX_Extent> <temporalElement> <EX_TemporalExtent> <extent> <gml:TimePeriod> <gml:beginPosition> 2006-01-11T16:22:25.00 </gml:beginPosition> <gml:endPosition> 2006-01-12T16:22:25.00 </gml:endPosition> </gml:TimePeriod> </extent> </EX_TemporalExtent> </temporalElement> </EX_Extent> </extent> </MD_DataIdentification> </identificationInfo></MD_Metadata>


Encoding issueTime in ISO 19115 & ISO 19139

issueTime …

metadata [MD_Metadata] » dateStamp [Date]

metadata [MD_Metadata] » identificationInfo [MD_DataIdentification] » citation [CI_Citation] » date [CI_Date] » date [Date] dateType [CI_DateTypeCode] edition [CharacterString] {creation, publication, revision} editionDate [Date]

Problem:• date field only …• in meteorology we need to differentiate on smaller

time scales• EITHER 1. extend metadata standard, OR2. use ‘edition’ information to capture metadata

information for amends etc.

issueTime …

metadata [MD_Metadata] » dateStamp [Date]


Problem:• date field only …• in meteorology we need to differentiate on smaller

time scales• EITHER 1. extend metadata standard, OR2. use ‘edition’ information to capture metadata

information for amends etc.

<MD_Metadata>

<dateStamp> <gco:Date>2006-02-20</gco:Date> </dateStamp>

<identificationInfo> <MD_DataIdentification> <citation> <CI_Citation> <date> <CI_Date> <date> <gco:Date>1993-01-01</gco:Date> </date> <dateType> <CI_DateTypeCode codeList="codeList.xml?CI_DateTypeCode" codeListValue="creation">creation</CI_DateTypeCode> </dateType> </CI_Date> </date> </CI_Citation> </citation> </MD_DataIdentification> </identificationInfo>

</MD_Metadata>

<MD_Metadata>

<dateStamp> <gco:Date>2006-02-20</gco:Date> </dateStamp>

<identificationInfo> <MD_DataIdentification> <citation> <CI_Citation> <date> <CI_Date> <date> <gco:Date>1993-01-01</gco:Date> </date> <dateType> <CI_DateTypeCode codeList="codeList.xml?CI_DateTypeCode" codeListValue="creation">creation</CI_DateTypeCode> </dateType> </CI_Date> </date> </CI_Citation> </citation> </MD_DataIdentification> </identificationInfo>

</MD_Metadata>


Indeterminate times in GML – ISO 19136

Inexact temporal positions may be expressed using the optional indeterminatePosition attribute. Thistakes a value from an enumeration defined as follows:

<simpleType name="TimeIndeterminateValueType"><restriction base="string">

<enumeration value="after"/><enumeration value="before"/><enumeration value="now"/><enumeration value="unknown"/>

</restriction></simpleType>

These values are interpreted as follows: “unknown” indicates that no specific value for temporal position is provided. “now” indicates that the specified value shall be replaced with the current temporal position whenever the value is accessed. “before” indicates that the actual temporal position is unknown, but it is known to be before the specified value. “after” indicates that the actual temporal position is unknown, but it is known to be after the specifiedvalue.

<gml:TimeInstant> <gml:timePosition indeterminatePosition="now"/></gml:TimeInstant>

<gml:TimeInstant> <gml:timePosition indeterminatePosition="now"/></gml:TimeInstant>


Times relevant to a simulation… time in the real world …

crea

tionT

ime

(t c)

Time at which the simulation was executed

issu

eTim

e (t i)

Time at results of the simulation were

published / issued

time axis (t)

Time of an ‘event’ that has been simulated …

i.e. a ‘simulated’ observation

datu

mTi

me

(t d)

The ‘origin’ (datum) time used in the

simulation

even

tTim

e (t e

)

x


Times relevant to a simulation… assimilation vs. prediction …

time axis (t)

datu

mTi

me

(t d) o

r

anal

ysis

Tim

e (t a

)

initi

alis

atio

nTim

e (t 0

)

assimilationperiod

Consider a forecast …

• the simulation is run to give a prediction from the datumTime (td) to some arbitrary time in the future

• however, the simulation begins earlier at the initialisationTime (t0)… allowing data to be assimilated into the simulation

• the analysis is produced at the end of the assimilation period

• the analysisTime (ta) corresponds with the datumTime (td)

Consider a forecast …

• the simulation is run to give a prediction from the datumTime (td) to some arbitrary time in the future

• however, the simulation begins earlier at the initialisationTime (t0)… allowing data to be assimilated into the simulation

• the analysis is produced at the end of the assimilation period

• the analysisTime (ta) corresponds with the datumTime (td)

even

tTim

e (t e

)

x


Times relevant to a simulation… usage periods …

time axis (t)

datu

mTi

me

(t d)

usag

eSta

rtTim

e

usag

eExp

iryTi

me

valid

Usa

gePe

riod

validUsagePeriod is the interval during which the results of the simulation should be used.

Most often, simulation results do not have a valid usage period. However, we must include the concept as it is required for TAFs

Whilst not obvious, the issueTime (ti) and the start of the usage period do not need to coincide

validUsagePeriod is the interval during which the results of the simulation should be used.

Most often, simulation results do not have a valid usage period. However, we must include the concept as it is required for TAFs

Whilst not obvious, the issueTime (ti) and the start of the usage period do not need to coincide

even

tTim

e (t e

)

validUsagePeriod may extend beyond the eventTime (te)

x


x

A set of results from a simulation (a ‘model run’)

time axis (t)

datu

mTi

me

(t d)

Collection of discrete simulation result-sets that share the same

DatumTime

even

tTim

e (t e

)fin

alTi

me

(t f)

End of the simulation …

finalTime (tf)colle

ctio

nPer

iod


Times relevant to a simulation … the axes of time for simulations …

real time axis (t)

simulationtime axis (T)

datu

mTi

me

(t d)

simulationDatumTime (Td)

simulationTime (Ts)

Example: T+60

The origin time for the simulation; e.g. T+0

even

tTim

e (t e

)

simulation time (T) is ‘projected’ onto real time (t) … although this is not always straightforward with 360-day

calendars for climate models!

simulation time (T) is ‘projected’ onto real time (t) … although this is not always straightforward with 360-day

calendars for climate models!





Time in the “conceptual world” of the numerical simulation

Temporal coordinate reference system defined locally for the

simulation using <gml:TimeCoordinateSystem>

Time in the “conceptual world” of the numerical simulation

Temporal coordinate reference system defined locally for the

simulation using <gml:TimeCoordinateSystem>


Example encoding of a local temporal reference system

Temporal coordinate reference system (hours since midnight UTC 9 th March 2006) encoded as:

<gml:TimeCoordinateSystem gml:id=“simTRS1"><gml:description>Number of hours since midnight UTC, 9th March 2006</gml:description><gml:name>Simulation time axis</gml:name><gml:domainOfValidity>global</gml:domainOfValidity><gml:origin>2006-03-09T00:00:00.00</gml:origin><gml:interval>H</gml:interval>

</gml:TimeCoordinateSystem>

Temporal coordinate reference system (hours since midnight UTC 9 th March 2006) encoded as:

<gml:TimeCoordinateSystem gml:id=“simTRS1"><gml:description>Number of hours since midnight UTC, 9th March 2006</gml:description><gml:name>Simulation time axis</gml:name><gml:domainOfValidity>global</gml:domainOfValidity><gml:origin>2006-03-09T00:00:00.00</gml:origin><gml:interval>H</gml:interval>

</gml:TimeCoordinateSystem>

Time instant “T+60” (relating to local temporal reference system) encoded as:

<gml:TimeInstant><gml:timePosition frame=“#simTRS1">60</gml:timePosition>

</gml:TimeInstant>

Time instant “T+60” (relating to local temporal reference system) encoded as:

<gml:TimeInstant><gml:timePosition frame=“#simTRS1">60</gml:timePosition>

</gml:TimeInstant>


Which time values are needed in simulation ‘metadata’?(at least for operational meteorology!)

datumTime (td) oranalysisTime (ta)

eventTime (te)

creationTime (tc)

issueTime (ti)

validUsagePeriod

usageStartTime

usageExpiryTime

initialisationTime (t0)

finalTime (tf)

‘publication’ metadata

‘publication’ metadata

primarymetadataprimary

metadata

‘simulation’metadata

‘simulation’metadata

collectionPeriod

simulatedTime (Ts)


Encoding primary time metadata in ISO 19115 & ISO 19139 (1)

Encode as for observations

…

except you *may* want to use two temporal extent definitions to describe time instants in both ‘Gregorian’

and ‘simulated’ reference frames


…

except you *may* want to use two temporal extent definitions to describe time instants in both ‘Gregorian’

and ‘simulated’ reference frames

eventTime (te)

collectionPeriod

simulatedTime (Ts)

<EX_Extent> <temporalElement> <EX_TemporalExtent> <extent> <gml:TimeInstant> <gml:timePosition> 2005-01-11T16:22:25.00 </gml:timePosition> </gml:TimeInstant> </extent> </EX_TemporalExtent> </temporalElement> <temporalElement> <EX_TemporalExtent> <extent> <gml:TimeInstant> <gml:timePosition frame=“#simTRS1"> 60 </gml:timePosition> </gml:TimeInstant> </extent> </EX_TemporalExtent> </temporalElement> </EX_Extent>

<EX_Extent> <temporalElement> <EX_TemporalExtent> <extent> <gml:TimeInstant> <gml:timePosition> 2005-01-11T16:22:25.00 </gml:timePosition> </gml:TimeInstant> </extent> </EX_TemporalExtent> </temporalElement> <temporalElement> <EX_TemporalExtent> <extent> <gml:TimeInstant> <gml:timePosition frame=“#simTRS1"> 60 </gml:timePosition> </gml:TimeInstant> </extent> </EX_TemporalExtent> </temporalElement> </EX_Extent>


Encoding primary time metadata in ISO 19115 & ISO 19139 (2)

eventTime (te)

simulatedTime (Ts)

Problem:1. it *may* be difficult for parsers to differentiate between multiple

temporal extents; e.g. when attempting to build an index on the content of the metadata record

2. there is no convenient placeholder for the local temporal reference system definition

• it *may* be necessary to extend the ISO 19115 metadata standard to allow alternate time extents to be specified, along with their local reference system definition

• use a ‘similar’ pattern to expressing multi-lingual alternatives for character strings …

Problem:1. it *may* be difficult for parsers to differentiate between multiple

temporal extents; e.g. when attempting to build an index on the content of the metadata record

2. there is no convenient placeholder for the local temporal reference system definition

• it *may* be necessary to extend the ISO 19115 metadata standard to allow alternate time extents to be specified, along with their local reference system definition

• use a ‘similar’ pattern to expressing multi-lingual alternatives for character strings …

cd Alternativ e temporal extent

Extent information::EX_TemporalExtent

+ extent: TM_Primitive

WMO_TemporalExtent WMO_LocalisedTemporalExtent

+ localReferenceSystem: TimeCoordinateSystem+alternateExtents

1..*1


Encoding ‘publication’ time metadata in ISO 19115 & ISO 19139



employing the CI_DateTypeCode to describe the ‘type’ of the publication



employing the CI_DateTypeCode to describe the ‘type’ of the publication

creationTime (tc)

issueTime (ti)

validUsagePeriod

usageStartTime

usageExpiryTime

Encode validUsagePeriod as <gml:TimePeriod>

<validUsagePeriod> <gml:TimePeriod> <gml:beginPosition> 2006-01-11T16:22:25.00 </gml:beginPosition> <gml:endPosition> 2006-01-12T16:22:25.00 </gml:endPosition> </gml:TimePeriod> </validUsagePeriod>

Encode validUsagePeriod as <gml:TimePeriod>

<validUsagePeriod> <gml:TimePeriod> <gml:beginPosition> 2006-01-11T16:22:25.00 </gml:beginPosition> <gml:endPosition> 2006-01-12T16:22:25.00 </gml:endPosition> </gml:TimePeriod> </validUsagePeriod>


Temporal usage constraints – extension required to ISO 19115?

ISO 19115 defines constraint information; the metadata required for managing rights to information including restrictions on access and use.

The metadata entity seems the most appropriate placeholder for temporal usage constraints … however, ISO 19115 only details:

• MD_LegalConstraints

• MD_SecurityConstraints cd Constraint classes

MD_Constraints

+ useLimitation: CharacterString

MD_LegalConstraints

+ accessConstraints: MD_RestrictionCode+ otherConstraints: CharacterString+ useConstraints: MD_RestrictionCode

MD_SecurityConstraints

+ classification: MD_ClassificationCode+ classificationSystem: CharacterString+ handlingDescription: CharacterString+ userNote: CharacterString


+metadataConstraints 0..*

To record temporal usage constraints in the metadata record, we will need to extend ISO 19115; e.g.

WMO_TemporalUsageConstraints

Question: is this type of metadata required in WMO core?


Encoding ‘simulation’ time metadata in ISO 19115 & ISO 19139

These metadata elements are artefacts of the numerical simulation itself.

Furthermore, there are potentially many more metadata elements which *may* prove useful to discriminate between datasets (e.g. ensembleID)

The British Atmospheric Data Centre (BADC) are working on an ISO 19115 extension to define metadata about numerical simulations:

http://proj.badc.rl.ac.uk/ndg/wiki/NumSim

These metadata elements are artefacts of the numerical simulation itself.

Furthermore, there are potentially many more metadata elements which *may* prove useful to discriminate between datasets (e.g. ensembleID)

The British Atmospheric Data Centre (BADC) are working on an ISO 19115 extension to define metadata about numerical simulations:

http://proj.badc.rl.ac.uk/ndg/wiki/NumSim

datumTime (td) oranalysisTime (ta)

…

initialisationTime (t0)

finalTime (tf)

ensembleID


NDG NumSim extension

Numerical Simulation Discovery Metadata (aka NumSim)

The DIF describes datasets at the discovery level, but where simulations are involved, discovery metadata needs more information than is available in existing schema.

A new schema which is being trialled at the BADC should be accessible to both DIF and ISO19115 parent discovery schema, although at the moment it is rather standalone.

…

Proposal: WMO adopts NumSim as a formal mechanism for describing simulation metadata within WMO Core metadata profile. Prior to adoption, WMO should liaise with BADC to ensure the the profile is fit for purpose and has been rigorously tested.


Thank you

Implementing codelists

3rd May 2006


Jürgen Seib, Deutscher Wetterdienst

Codelists

A permissible extension of ISO 19115 is that ‘free text’ content can be restricted by the use of a codelist

Furthermore, existing codelists can be extended by adding more terms to the list

Note that this is NOT possible with enumerations – an enumeration is NOT extensible

An «Enumeration» is implemented as an XML schema enumeration list

A «Codelist» is implemented as a codelist catalogue file WMO Core profile v0.2 identified a small number of *new*

code lists

ISO/TS 19139:2005(E) – Clause 8.5.5Codelist encodings (1)

A class that is stereotyped CodeList is an enumerated type like a class that is stereotyped Enumeration.

The difference is that the <<CodeList>> class is extensible.

All <<CodeList>> classes defined in ISO 19115, Annex B, are described in tables with three columns: Name, DomainCode and Definition.

Codelists and their associated definitions are controlled in a register. ISO 19115, Annex B contains the content of a register or registers that could be created that is well understood by software.

ISO/TS 19139:2005(E) – Clause 8.5.5Codelist encodings (2)

The last point is the crucial *implementation* issue … Values of a codelist are NOT encoded in the

schema (as is the case for an enumeration) Codelist values are stored in some external register

Issue: XML validation CANNOT verify codelist entries

Implementing code lists: alternative

define all WMO code lists of type «enumeration»

Issues:

1) Enumeration does not support multi-language

2) Codelists as enumerations is INFLEXIBLE … it does not permit extension (or local extension) … refer to complexity regarding BUFR

3) XML schema gives SYNTACTIC interoperability via XML schema validation … we need SEMANTIC interoperability via application-level parser

ISO 19139 Codelist schema

Where codelists are referenced from within a metadata record, the following XML type is used:

<xs:complexType name="CodeListValue_Type"> <xs:simpleContent> <xs:extension base="xs:string"> <xs:attribute name="codeList" type="xs:anyURI" use="required"/> <xs:attribute name="codeListValue" type="xs:anyURI“ use="required"/> <xs:attribute name="codeSpace" type="xs:anyURI" use="optional"/> </xs:extension> </xs:simpleContent></xs:complexType>

Example instance values:

codeList = http://www.tc211.org/ISO19139/resources/codeList.xml#CI_DateTypeCodecodeListValue="creation"

Codelist implementation example – CI_DateTypeCode (1)

The XML global element corresponding to CI_DateTypeCode:<xs:element name="CI_DateTypeCode" type="gco:CodeListValue_Type"substitutionGroup="gco:CharacterString"/>

The XML PropertyType corresponding to CI_DateTypeCode:<xs:complexType name="CI_DateTypeCode_PropertyType"> <xs:sequence> <xs:element ref="gmd:CI_DateTypeCode" minOccurs=”0”/> </xs:sequence> <xs:attribute ref="gco:nilReason"/></xs:complexType>

cd CD

«CodeList»CI_DateTypeCode


Codelist implementation example – CI_DateTypeCode (2)

<CI_Date> <date> <gco:Date>1993-01-01</gco:Date> </date> <dateType> <CI_DateTypeCode codeList="./resources/codeList.xml#CI_DateTypeCode" codeListValue="publication">publication</CI_DateTypeCode> </dateType></CI_Date>

… implementation of codelist registers will be discussed later …

cd CD

«CodeList»CI_DateTypeCode


WMO metadata profile codelist extensions

WMO Core profile v0.2 identified a small number of *new* ‘code lists’:

WMO topic categories «enumeration» WMO keywords «thesaurus» WMO data frequency code «codelist» WMO member countries «codelist»

Code lists: WMO topic categories

MD_TopicCategoryCode far too restrictive …

Create new WMO specialisation:

WMO_CommunityTopicCategoryCode

(as proposed in WMO Core v0.2)

cd topic category

«Enumeration»Identification information::MD_TopicCategoryCode

+ biota+ boundaries+ climatologyMeteorologyAtmosphere+ economy+ elevation+ environment+ farming+ geoscientificInformation+ health+ imageryBaseMapsEarthCover+ inlandWaters+ intell igenceMilitary+ location+ oceans+ planningCadastre+ society+ structure+ transportation+ util i tiesCommunication

«Enumeration»WMO_CommunityTopicCategoryCode

+ actinometry: + aerology: + agricultureMeteorology: + airplaneObservation: + airPollution: + climatology: + glaciology: + hydrology: + landHydrology: + landMeteorologyClimate: + landPollution: + landWaterPollution: + marineAerology: + marineMeteorology: + meteorology: + observationPlatform: + oceanography: + pollution: + rocketSounding: + satell iteObservation: + seaPollution: + synopticMeteorology: + waterPollution: + weatherForecasts: + weatherObservations:

WMO topic categories - schema

<xs:simpleType name=“WMO_CommunityTopicCategoryCode_Type"> <xs:restriction base="xs:string"> … <xs:enumeration value=“weatherObservations"/> … </xs:restriction></xs:simpleType>

<xs:element name=“WMO_CommunityTopicCategoryCode" type=“wmo:WMO_CommunityTopicCategoryCode_Type" substitutionGroup=“gmd:MD_TopicCategoryCode_PropertyType"/>

<xs:complexType name=“WMO_CommunityTopicCategoryCode_PropertyType"> <xs:sequence>

<xs:element ref=“wmo:WMO_CommunityTopicCategoryCode" minOccurs="0"/> </xs:sequence> <xs:attribute ref="gco:nilReason"/></xs:complexType>

Example: WMO topic categories

<MD_Metadata>...... <topicCategory> <MD_TopicCategoryCode> climatologyMeteorologyAtmosphere </MD_TopicCategoryCode> </topicCategory> <topicCategory xsi:type=“wmo:WMO_CommunityTopicCategoryCode_PropertyType”> <WMO_CommunityTopicCategoryCode> weatherObservation </WMO_CommunityTopicCategoryCode> </topicCategory>.......</MD_Metadata>

(This part *may* not be required)

SIMDAT: metadata directory structure (1)

SIMDAT (phase 1) employed WMO Core Metadata v0.2 <topicCategory> was ‘misused’ to hold a ‘directory structure’ for the metadata

instance …

Example:

<topicCategory>

NWP Outputs > ECMWF > 40 years reanalysis

</topicCategory>

This implementation is NOT ISO 19115 compliant

Proposal:

Use MD_DataIdentification » supplementalInformation as a placeholder for the ‘directory’

Code lists: WMO keywords

MD_KeywordTypeCode … WMO Core v0.2 proposed a new WMO

keyword list:

WMO_KeywordList

(a VERY long list!)

WMO Core v0.2 expressed this as an enumeration …

Also put the actual keyword list *content* into the keyword *type* list (?)

cd keywords

«CodeList»Identification information::

MD_KeywordTypeCode

+ discipline+ place+ stratum+ temporal+ theme

Identification information::MD_Keywords

+ keyword: CharacterString+ thesaurusName: CI_Citation+ type: MD_KeywordTypeCode

ISO 19139 keywords implementation

keyword … ‘free text’ field

type … from «MD_KeywordTypeCode» codelist

classifies the type of keyword does this codelist need extension?

thesaurusName … «CI_Citation»

identifies the ‘thesaurus’ that describes the permissible content of the keyword list

thesaurusName [CI_Citation] »

identifier [MD_Identfier] »

code [CharacterString]

can be used to express the URI of the thesaurus / codelist … allowing linkage to URL or URN

(alternative: substitute gmx:Anchor for gco:CharacterString to reference the ‘thesaurus’)

cd keywords

«CodeList»Identification information::

MD_KeywordTypeCode

+ discipline+ place+ stratum+ temporal+ theme

Identification information::MD_Keywords

+ keyword: CharacterString+ thesaurusName: CI_Citation+ type: MD_KeywordTypeCode

WMO keyword – thesaurus implementation

Keyword thesaurus content (i.e. the list of keywords and their meanings) can be implemented as

a) URN linkage to existing WMO code manualsurn:x-wmo:wmoManual:306:synop ???

(note: an application will need some additional, pre-defined context to dereference the URN)

b) URL linkage to online catalogue; encoded according to the codelist catalogue pattern (see later)

Code lists: frequency values

MD_MaintenanceFrequencyCode too restrictive …

WMO Core v0.2 proposed an extended list:

WMO_DataFrequencyCode

expressed as an enumeration in WMO Core v0.2

cd frequency v alues

«CodeList»WMO_DataFrequencyCode

+ 1-minute: + 10-daily: + 10-minute: + 12-hourly: + 15-minute: + 3-hourly: + 30-minute: + 5-minute: + 6-hourly: + 8-hourly: + annually: + biannually: + continuous: + daily: + decadally: + fortnightly: + hourly: + irregularly: + monthly: + quarterly: + weekly:

«CodeList»Maintenance information::

MD_MaintenanceFrequencyCode

+ annually+ asNeeded+ biannually+ continual+ daily+ fortnightly+ irregular+ monthly+ notPlanned+ quarterly+ unknown+ weekly

WMO_DataFrequencyCode implementation

Standard codelist implementation …

Global XML element …

<xs:element name=“WMO_DataFrequencyCode" type="gco:CodeListValue_Type"

substitutionGroup="gco:CharacterString"/>

XML PropertyType …

<xs:complexType name=“WMO_DataFrequencyCode_PropertyType"> <xs:sequence> <xs:element ref=“wmo:WMO_DataFrequencyCode" minOccurs=”0”/> </xs:sequence> <xs:attribute ref="gco:nilReason"/></xs:complexType>

WMO_DataFrequencyCode example

<MD_MaintenanceInformation>

…

<maintenanceAndUpdateFrequency xsi:type=“wmo:WMO_DataFrequencyCode_PropertyType”>

<wmo:WMO_DataFrequencyCode codeList="codeList.xml?WMO_DataFrequencyCode" codeListValue="daily">daily</wmo:WMO_DataFrequencyCode>

</maintenanceAndUpdateFrequency>

...

</MD_MaintenanceInformation>

Code lists: WMO member countries

The organisation responsible for various aspects of the metadata instance is defined thus:

[CI_Citation] »

citedResponsibleParty [CI_ResponsibleParty] »

organisationName [CharacterString]

WMO profile needs to formalise list of responsible organisations as the member countries of WMO

WMO_WMO-MemberCountryCode

WMO_WMO-MemberCountryCode implementation

Standard codelist implementation …

Global XML element …<xs:element name=“WMO_WMO-MemberCountryCode"

type="gco:CodeListValue_Type"substitutionGroup="gco:CharacterString"/>

XML PropertyType …<xs:complexType name=“WMO_WMO-MemberCountryCode_PropertyType"> <xs:sequence> <xs:element ref=“wmo:WMO_WMO-MemberCountryCode“ minOccurs=”0”/> </xs:sequence> <xs:attribute ref="gco:nilReason"/></xs:complexType>

WMO_WMO-MemberCountryCode example

<CI_Citation> … <citedResponsibleParty> <CI_ResponsibleParty> <organisationName> <wmo:WMO_WMO-MemberCountryCode codeList="codeList.xml?

WMO_WMO-MemberCountryCode" codeListValue="Deutscher Wetterdienst">Deutscher Wetterdienst

</wmo:WMO_WMO-MemberCountryCode> </organisationName> </CI_ResponsibleParty> </citedResponsibleParty> ...</CI_Citation>

Member country list – alternative implementation

does not exist in WMO Metadata Profile v0.2should be implemented as an XML enumeration type

<xs:simpleType name="WMO_MemberCountriesCodeType"> <xs:restriction base="xs:string"> <xs:enumeration value=”France"/> <xs:enumeration value=”Germany"/> ....... </xs:restriction></xs:simpleType>

<xs:element name="Country” type="wmo:WMO_MemberCountriesCodeType” substitutionGroup="gmd:Country"/>

Member country list – alternative implementation

<MD_Meatadata>...... <locale> <PT_Locale> <languageCode/> <country> <wmo:Country>Germany</wmo:Country> </country> <characterEncoding> .......</MD_Metadata>

Thank you

Service metadata

Encoding in ISO 19119 metadata

May 2006

Service metadata

WMO Core Profile key concern is describing *datasets* …

Implication:

MD_DataIdentification is sufficient?

This is NOT the case … Where a dataset is described (i.e. via a WMO Core

metadata record) you need to be able to identify the *service* by which you can *access* the data …

Example: when a GISC ‘harvests’ metadata records from a DCPC

(refer to plans for CBS Workshop demonstration Nov 2006)

Service metadata in ISO 19115

cd serv ice metadata



MD_Identification


Identification information::

MD_Serv iceIdentification

+identificationInfo 1..*

ISO 19119:2005 Geographic information - Services

Service metadata is described in ISO 19119 MD_ServiceIdentification is replaced with

SV_ServiceIdentification The ISO standard discusses much more than

simple *access* services … e.g. defining metadata constructs that can be used to describe service chaining

Alternative service description standards (including WSDL) were deemed incomplete and insufficient

ISO 19119:2005 UML model (1)cd Figure 2 - Serv ice metadata class diagram


MD_Identification

+ abstract: CharacterString+ citation: CI_Citation+ credit: CharacterString+ pointOfContact: CI_ResponsibleParty+ purpose: CharacterString+ status: MD_ProgressCode


+ characterSet: MD_CharacterSetCode = "utf8"+ environmentDescription: CharacterString+ extent: EX_Extent+ language: CharacterString+ spatialRepresentationType: MD_SpatialRepresentationTypeCode+ spatialResolution: MD_Resolution+ supplementalInformation: CharacterString [0..1]+ topicCategory: MD_TopicCategoryCode

«CodeList»DCPList

+ COM: + CORBA: + JAVA: + SQL: + WebServices: + XML:

«CodeList»SV_CouplingType

+ light: + loose: + mixed:

«enumeration»SV_ParameterDirection

+ in: + in/out: + out:

SV_Serv iceIdentification

+ accessProperties: MD_StandardOrderProcess [0..1]+ coupledResource: SV_CoupledResource [0..*]+ couplingType: SV_CouplingType+ extent: EX_Extent [0..*]+ restrictions: MD_Constraints [0..1]+ serviceType: GenericName+ serviceTypeVersion: CharacterString [0..*]

SV_OperationMetadata

+ connectionPoint: CI_OnlineResource [1..*]+ DCP: DCPList [1..*]+ invocationName: CharacterString [0..1]+ name: MemberName+ operationDescription: CharacterString [0..1]+ operationName: CharacterString

SV_CoupledResource

+ identifier: CharacterString+ operationName: CharacterString

SV_OperationChainMetadata

+ description: CharacterString [0..1]+ name: CharacterString

«DataType»SV_Parameter

+ description: CharacterString [0..1]+ direction: SV_ParameterDirection [0..1]+ optionality: CharacterString = "Mandatory"+ repeatabil ity: Boolean

«Metaclass»Type

+valueType

+parameters 1

+operation

+operation 1..* {ordered}

Chaining Metadata

+dependsOn

Dependencies

+containsOperations

+operatesOn

ISO 19119:2005 UML model (2)

cd serv ice binding classes

MD_Identification

SV_Serv iceIdentification

+ accessProperties: MD_StandardOrderProcess [0..1]+ coupledResource: SV_CoupledResource [0..*]+ couplingType: SV_CouplingType+ extent: EX_Extent [0..*]+ restrictions: MD_Constraints [0..1]+ serviceType: GenericName+ serviceTypeVersion: CharacterString [0..*]

SV_CoupledResource

+ identifier: CharacterString+ operationName: CharacterString

SV_OperationChainMetadata

+ description: CharacterString [0..1]+ name: CharacterString

SV_OperationMetadata

+ connectionPoint: CI_OnlineResource [1..*]+ DCP: DCPList [1..*]+ invocationName: CharacterString [0..1]+ name: MemberName+ operationDescription: CharacterString [0..1]+ operationName: CharacterString

«CodeList»DCPList

+ COM: + CORBA: + JAVA: + SQL: + WebServices: + XML:

«CodeList»SV_CouplingType

+ light: + loose: + mixed:

«DataType»SV_Parameter

+ description: CharacterString [0..1]+ direction: SV_ParameterDirection [0..1]+ optionality: CharacterString = "Mandatory"+ repeatabil ity: Boolean

«Metaclass»Type

«enumeration»SV_ParameterDirection

+ in: + in/out: + out:

+operation 1..* {ordered}

Chaining Metadata

+dependsOn

Dependencies

+containsOperations

+parameters 1+operation

+valueType

ISO 19119:2005 – implementation (1)

ISO 19119 seems to meet requirements But …

1. there is no ISO-ratified encoding (equivalent to ISO 19139) although an incomplete (?) ISO 19118 compliant XML

encoding exists from OGC CSW initiative

2. there does not appear to be a place holder to reference pre-existing WSDL definitions

most implementation examples I have seen (OGC service offerings) have a WSDL definition in *parallel* to an ISO 19119 definition


Best practice for WMO Core metadata? Bind the service definition to the dataset via the operatesOn

relationship (via xlink reference) Set SV_CouplingType as ‘mixed’

Alternative ‘data access’ service binding?

[MD_Distribution] »

transferOptions [MD_DigitalTransferOptions] »

onLine [CI_OnlineResource]

Extend CI_OnlineResource to hold SV_ServiceIdentification, wsdl:definition & default values / predefined queries?


Incorporating WSDL service definitions?

Include *both* SV_ServiceIdentification and wsdl:definitions elements …

<MD_Metadata> … <identificationInfo> <MD_DataIdentification>…</MD_DataIdentification> </identificationInfo> <identificationInfo> <SV_ServiceIdentification>…</SV_ServiceIdentification> </identificationInfo> <identificationInfo xsi:type=“wsdl:definitions?”> <types>…</types> <message>…</message> <portType> <operation>…</operation> </portType> <binding>…</binding> <service>…</service> </identificationInfo> …</MD_Metadata>

Default parameters / parameter ranges

SIMDAT (phase 1) implemented ‘bespoke’ service binding constructs

ISO 19119 provides alternative implementation …

Except for a mechanism for identifying “default” (fixed) values & ranges of values

Extend ISO standard information model to cater for default values or range lists?

<location>int.ecmwf.mars</location><request> <class>e4</class> <levtype>sfc</levtype> <database>marser</database> <grid>2/2</grid></request><variables> <date type=“date”> <startDate>1980-01-01</startDate> <endDate>1990-12-31</endDate> </date> <time title=“Base time” multiple=“1”

type=“enum”> <value>0000</value> <value>1200</value> </time></variables>

Thank you

Catalogues and registries

3rd May 2006


Jürgen Seib, Deutscher Wetterdienst

Feature catalogues

Current WMO Core best practice: dataset content identified via keywords

Alternative: define content model as GML feature … a ‘feature type’

UK Met Office undertaking to develop GML feature types for meteorological information

(http://www.metoffice.gov.uk/informatics)

Feature types are registered in a ‘feature catalogue’

cd feature catalogues


«Abstract»Content information::MD_ContentInformation

Content information::MD_FeatureCatalogueDescription

+ complianceCode: Boolean+ featureCatalogueCitation: CI_Citation+ featureTypes: GenericName+ includedWithDataset: Boolean+ language: CharacterString

+contentInfo 0..*

Feature catalogue - implementation

Best practice implementation for feature catalogues is ‘in flux’ ISO standards:

ISO 19110: Geographic information – Methodology for feature cataloguing (new work item)

ISO 19126: Geographic information – Profiles for feature data dictionary registers and feature catalogue registers

ISO 19135 Geographic Information – Procedures for registration of items of geographic information

Open Geospatial Consortium initiatives:

MOTIIVE; INSPIRE-related project aiming to develop best practice methodology for implementing feature catalogues within registries

Supporting metadata

A key objective of IPET-MI is to define the schemas for WMO Core metadata …

However, a number of resources are *external* to the metadata instances …

Coordinate Reference System definitions Unit of Measure definitions Phenomena (parameter) definitions Codelists Keyword thesauri Feature catalogues Gazetteers Station lists

Registries and catalogues (1)

These ‘supporting’ metadata artefacts are registered in a *catalogue* or *registry*

Definition: a registry is a catalogue with *governance*

How do you implement a catalogue?

Simple: create an XML instance document containing the

registered definitions & reference the content via hyperlinks

Issue: ‘brittle’ implementation – relies on fixed URLs … susceptible to ‘broken links’

Registries and catalogues (2)

Feature rich: import the content into a *repository* and use a

sophisticated registry to index the definitions, abstracting the *real* location of the documents, enabling the expression of rich content models and the traversal of associations between resources

Issue: complex implementation, limited reference implementations

UK Met Office have undertaken to develop a registry-repository implementation based on OGC CSW and ebRIM 3.0; planned demonstration at CBS Workshop, Nov 2006

ISO 19139 catalogue implementation

3 ‘concrete’ catalogue classes:

1. Coordinate Reference System

2. Unit of Measure

3. Codelistcd Figure 10 - Catalogues

«Abstract»CT_Catalogue

+ characterSet: MD_CharacterSetCode [0..1]+ fieldOfApplication: CharacterString [0..*]+ language: CharacterString [0..1]+ locale: PT_Locale [0..*]+ name: CharacterString+ scope: CharacterString [1..*]+ versionDate: Date+ versionNumber: CharacterString

CT_CrsCatalogue CT_UomCatalogue CT_CodelistCatalogue

ISO 19139 … codelist catalogue implementation

Example: CT_CodelistCatalogue

cd Figure 13 - Codelist Catalogue

CT_Catalogue

CT_CodelistCatalogue

CT_Codelist

«Abstract»CT_Item

+ definition: CharacterString+ description: CharacterString [0..1]+ identifier: GenericName+ name: GenericName [0..*]

CT_CodelistValue+codeEntry

1..*1

+codeListItem 1..*1

Codelist catalogue – XML encoding

cd Figure 69 - Codelist items - XML implementation

«Abstract»CT_Item

+ definition: CharacterString+ description: CharacterString [0..1]+ identifier: GenericName+ name: GenericName [0..*]

CT_Codelist

CT_CodelistValue

AbstractGML

«ObjectType»dictionary::Definition

+ remarks: string [0..1]

«ObjectType»dictionary::Dictionary

«xs:element»gmx:

CodeDefinition

«xs:element»gmx:

CodelistDictionary

+codeEntry

1..*

1

+codeEntry

1..*

«XCGE»

«XCGE»

«XCGE»

Also a ‘multi-lingual’ implementation available from ISO 19139

Additional catalogues …

CT_KeywordCatalogue CT_StationCatalogueCT_CentreCatalogue CT_ParameterCatalogue

Volume A: observing stations

hierarchy: WMO region countrystation namestation index number latitude and longitudeelevation in metres

the elevation of the station (HP) the elevation of the ground (H) or the official altitude of the

aerodrome (HA)

pressure level in HPaobservation times remarks

Catalogues: station catalogue

CharacterString(from Text)

GlobalStationId

+code: IntStationCode

LocalStationId

+code: GenericName

<<Enumeration>>IntStationCode

+WMO+ICAO

MeteorologicalCentre(from WMO namespace)

+owner

CT_StationCatalogue

1..* +station

WMO_Station+stationName: CharacterString+country: CharacterString+wmoRegion: integer+latitude[0..1]: Decimal+longitude[0..1]: Decimal+elevationHP[0..1]: double+elevationH[0..1]: double+elevationHA[0..1]: double+pressureLevel[0..1]:integer+remarks[0..1]: CharacterString

0..*+stationId

<<Abstract>>StationId

Product

+productID: GenericName+timePerid[0..1]: TM_Period+accessRights[0..1]: MD_Constraints+quality[0..1]: DQ_DataQuality

0..*+product

CI_Contact(from Metadata CI package)

0.. 1+stationContact

Another UML model for stations

0..*+stationId

<<Abstract>>StationId

WMO_Station

+stationName: CharacterString+remarks[0..1]: CharacterString

CI_Contact(from Metadata CI package)

0.. 1+stationContact

LandSurfaceStation

+country: CharacterString+wmoRegion: integer+latitude[0..1]: Decimal+longitude[0..1]: Decimal+elevationHP[0..1]: double+elevationH[0..1]: double+elevationHA[0..1]: double+pressureLevel[0..1]:integer

0..*+product

Product(from WMO namespace)

Ship(from WMO namespace)

Airplane(from WMO namespace)

Buoys(from WMO namespace)

RadiosondeStation(from WMO namespace)

Catalogues: station catalogue

Use <gmx:Anchor> to reference a station<geographicElement>

<EX_GeographicDescription>

<geographicIdentifier>

<MD_Identifier>

<code>

<gmx:Anchor xlink:href=“station.xml#2667”>

Köln-Bonn</gmx:Anchor>

</code>

</MD_Identifier>

</geograhicIdentifier>

</EX_GeographicDescription>

</geographicElement>

Catalogues: parameter catalogue

1..* +parameter

CT_ParameterCatalogue

MeteorologicalParameter

+name: CharacterString+shortName[0..1]: GenericName+frequency: duration

1 +element

MeteorologicalElement

+name: CharacterString+shortName[0..1]: GenericName+unitOfMeasure: Unit

Aggregation

+function: AggregationCode+interval: duration

0..1 +subAggregation

0..1+aggregation

<<Enumeration>>AggregationCode

+minimum+maximum+mean+average+sum

Also see • NASA’s ‘SWEET’ ontology, and• Observations & Measure phenomena dictionary

ISO 19112:2003 - Geographic information — Spatial referencing by geographic identifiers

cd Gazeteer

Gazetteer::SI_Gazetteer{root,leaf}

+ name: RS_Identifier+ scope[0..1]: CharacterString+ territoryOfUse: EX_GeographicExtent+ custodian: + coordinate_system[0..1]: SC_CRS+ isGlobal: Boolean+ acceptableClassList: Set<TypeName> = {Any}

ReferenceSystem by Identifier::SI_LocationType{root,leaf}

+ name: RS_Identifier+ theme: CharacterString+ identifier: CharacterString+ definition: CharacterString+ owner: + territoryOfUse: EX_GeographicExtent

positions must be recorded if the geographic identifier contains insufficient information to identify location

Gazetteer::SI_LocationInstance{root,leaf}

+ geographicIdentifier: CharacterString+ alterrnativeGeographicIdentifier[0..*]: CharacterString+ geographicExtent[0..1]: EX_GeographicExtent+ temporalExtent[0..1]: EX_TemporalExtent+ administrator: + position[0..1]: GM_Point

ReferenceSystem by Identifier::SI_SpatialReferenceSystemUsingGeographicIdentifiers

{leaf}

+ theme: CharacterString+ overallOwner: + territoryOfUse: EX_GeographicExtent

1..*+locationType1..*+locationTypes

0..*+referenceSystem

+child 0..*

+parent 0..*

1..*+comprises

1..*+gazetteer

+parent 0..*

+child 0..*

1

+locationType

Gazetteer implementation – OGC 05-035 (1)

Within the OGC community there is a growing interest in the development of a common feature-based model for access to named features, often referred to as a gazetteer.

OGC 05-035 aims to implement a Gazetteer Service as a profile of the OGC Web Feature Service

Gazetteer Service is a specialized profile of a Web Feature Service that specifies a minimum set of FeatureTypes and operations required to support an instance of a gazetteer service

Gazetteer implementation – OGC 05-035 (2)

By using the capabilities of a Web Feature Server, the Gazetteer Service as proposed here exposes the following interfaces to query location instances in a gazetteer database:

Get or Query features based on thesaurus-specific properties (broader term (BT), narrower term (NT), related term (RT)

Retrieve properties of the gazetteer database, such as the location type class definitions and the spatial reference system definitions

Gazetteer implementation – interim

The Gazetteer Service (WFS-G) initiative has developed a set of ISO 19118-compliant XML encodings for the ISO 19112 information model:

SI_Gazetteer «FeatureType»

SI_LocationInstance «FeatureType»

SI_LocationType «FeatureType»

…

Recommendation: liaise with OGC regarding development of WFS-G Interim: use the ISO 19112 schema definitions to create a XML

instance document for the gazetteer definitions & reference these via xlink from metadata instances

Simple implementation

Poor functionality (serving ONLY as a list)

Thank you

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