Geography Markup Language: Information communities and their information models in the context of ge

1
Geography Markup Language Information
communities and their information models in the
context of geospatial web services

• Simon Cox
• CSIRO Exploration Mining
• http//www.em.csiro.au

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Outline

• XML GML
• GML Application Languages
• Conventional data models
• GML and Web Services
• GML deployments?
• SCOTS implementations?

3
XML

• Plain-text serialisation of structured
  information
• Meaningful tag names
• Semantics and model must be agreed by sender and
  receiver, either
• private agreements
• vendor standards
• open standards

ltgmlFeature gmlid"R456"gt ltgmldescriptiongtEx
ploration boreholelt/gmldescriptiongt
ltgmlnamegtnorth_r_679lt/gmlnamegt
ltgmllocationgt ltgmlPoint
srsName"urngalocalGrid68" gmlid"c679"gt
ltgmlposgt ... lt/gmlposgt lt/gmlPointgt
lt/gmllocationgt lt/gmlFeaturegt
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Geography Markup Language

• Standards-based geographic information transport
• feature meta-model
• element name feature-type
• content properties of this feature-type
• common components
• geometry, topology, temporal
• observations
• coverages
• coordinate reference systems, etc

ltgmlFeature gmlid"R456"gt ltgmldescriptiongtEx
ploration boreholelt/gmldescriptiongt
ltgmlnamegtnorth_r_679lt/gmlnamegt
ltgmllocationgt ltgmlPoint
srsName"urngalocalGrid68" gmlid"c679"gt
ltgmlposgt ... lt/gmlposgt lt/gmlPointgt
lt/gmllocationgt lt/gmlFeaturegt

• v3.0 Open GIS Consortium
• January 2003
• v3.1 - ISO 19136
• ?2004

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GML and web-services

• GML is canonical representation for OGC WFS
  request and response
• Service implemented as a set of request-response
  message pairs
• Fine-grained information transport
• Key to Spatial Data Infrastructures?

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Conventional information models UML

• Basic feature model

ltgmlFeature gmlid"R456"gt ltgmldescriptiongtEx
ploration boreholelt/gmldescriptiongt
ltgmlnamegtnorth_r_679lt/gmlnamegt
ltgmllocationgt ltgmlPoint
srsName"urngalocalGrid68" gmlid"c679"gt
ltgmlposgt ... lt/gmlposgt lt/gmlPointgt
lt/gmllocationgt lt/gmlFeaturegt

• extended for specific applications
• GML Application Languages

• UML -gt GML allows mapping to ISO TC/211

• class name feature-type
• borehole
• road
• school, etc
• attribute association names properties of
  this feature-type

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Conventional information models table
ltxmmlBorehole gmlid"R456"gt
ltgmldescriptiongtExploration holelt/gmldescription
gt ltgmlnamegtnorth_r_679lt/gmlnamegt
ltxmmlcollarLocationgt ltgmlPoint
srsName"urngalocalGrid68" gmlid"c679"gt
ltgmlposgt ... lt/gmlposgt lt/gmlPointgt
lt/xmmlcollarLocationgt ltxmmlcollarDiameter
uom"m"gt0.15ltxmmlcollarDiametergt ltxmmlshape
xlinkhref"http//my.big.org/borehole_surveys/s67
9"/gt lt/xmmlBoreholegt
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Private vs. public schemas

• WFS is a façade to a DB or GIS

• Data-store organised for custodians requirements
• esp. maintenance

• If no schema-mapping, either
• every database must use same table structure
• every service will deliver a different data model

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Conventional information models table
ltxmmlBorehole gmlid"R456"gt
ltgmldescriptiongtExploration holelt/gmldescription
gt ltgmlnamegtnorth_r_679lt/gmlnamegt
ltxmmlcollarLocationgt ltgmlPoint
srsName"urngalocalGrid68" gmlid"c679"gt
ltgmlposgt ... lt/gmlposgt lt/gmlPointgt
lt/xmmlcollarLocationgt ltxmmlcollarDiameter
uom"m"gt0.15ltxmmlcollarDiametergt ltxmmlshape
xlinkhref"http//my.big.org/borehole_surveys/s67
9"/gt lt/xmmlBoreholegt
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Use community standards at the interface
WFS Server
WFS Client (e.g. visualisation)

• Common encoding interoperability within the
  community
• No private agreements required for service binding

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Implementing a community language

• 2 aspects to be defined
• The principle elements - in a Feature-type
  catalogue
• formal description uses XML Schema
• based on GML to ensure WFS compatibility
• Vocabularies of valid property values
• schema enumerations
• references to external dictionaries

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Design method (XMML)

• Iterate between XML instances, XML Schema, UML
  model, harmonising with current state of suite of
  schemas
• Adapt existing standard
• e.g. GGIPAC, ASEG
• Private model from dominant data provider
• e.g. Geoscience Australia
• Sponsor requirements
• e.g. Fractal Technologies, CSIRO/pmdCRC, BGS,
  Snowdens/WMC/Newmont
• Consultation with stakeholders
• TWiki

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GML deployments

• Ordnance Survey - MasterMap
• US CIPI (Pilot)
• WFS services
• XMML
• pmdCRC modelling software framework
• ADX Assay Lab reporting standard
• endorsed by GGIPAC for Australian Geological
  Surveys
• WFS planned for various SDIs

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SCOTS implementations (WFS)

• from commercial vendors
• ArcIMS WFS Connector (http//www.esri.com/software
  /opengis/interopdownload.html )
• Cartalinea ( http//www.galdosinc.com )
• CubeServ WFS ( http//www.cubewerx.com/ )
• GeoMedia ( http//imgs.intergraph.com/gmwm/feature
  s.asp )
• MapAccess ( http//www.syncline.com/ )
• RedSpiderWeb ( http//www.ionicenterprise.com/ )
• use various methods to customise support of a
  community GAS (or not )
• Open Source solutions
• Deegree ( http//deegree.sourceforge.net/ )
• GeoServer ( http//geoserver.sourceforge.net/ )

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Open GIS Consortium

• January 2002
• Various Simple Features specs
• OLE/COM/CORBA/SQL
• Grid Coverages
• COM/Corba
• Web Map Server 1.0
• maps-as-images
• Catalogue services 1.0
• GML 2.1

• Now
• Various Simple Features specs
• OLE/COM/CORBA/SQL
• Grid Coverages
• COM/Corba
• Web Map Service 1.1.1
• maps-as-images
• Catalogue services 1.0
• GML 3.0
• Web Feature Service 1.0
• reusable data
• Filter Encoding 1.0
• common query language
• Styled Layer Descriptor 1.0
• rules for portrayal
• Web Map Context 1.0
• combinations/state
• Web Coverage Service
• TC Vote underway

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Questions?

• http//xmml.arrc.csiro.au
• http//www.opengis.org