An Open Source Linked Data Infrastructure for Publishing
Geospatial DataArif Shaon, Andrew Woolf, Shirley
Crompton, Will Rogers, Mike Jackson, Robert Boszec
“Place matters…”
• “everything happens somewhere”– Location Strategy for the UK
• Combine information about places– Stretch of road– Speed limit orders– Underground pipes, cables, ducts– Accident statistics
• Benefits– Improve decision making– Deliver better services
Querying location data
GIS Service (Known)
GIS Service (Unknown)
query
query
INSPIRE• EU directive
– 15th May 2007– http://inspire.jrc.ec.europa.eu/
• EU-wide infrastructure for spatial information– All levels/scales of detail
• Standard– Model ontology in UML– Expose as XML– Access via web services
Semantic Web
Linked data
• Use URIs as names for things• Use HTTP URIs so that people can look up those
names• When someone looks up a URI, provide useful
information, using the standards (RDF, SPARQL)• Include links to other URIs, so that they can
discover more thingsTim Berners-Lee
Querying linked location data
Linked GIS Service (Known)
Linked GIS Service (Unknown)
Query (URI/SPARQL)
Query (URI/SPARQL)
Querying linked location data
• Potential for developing more flexible means of data sharing and accessibility
• Potential for solving the problems of data harmonisation through complex web services
Linked GIS Service (Known)
Linked GIS Service (Unknown)
Query (URI/SPARQL)
Query (URI/SPARQL)
Location URIs for the UK• “Designing URI sets for location”, 2010
– STFC advised on development
• Part of the UK Location Strategy
• Extend INSPIRE to include linked data publication
URIs for the UK public sector
• “Designing URI Sets for the UK Public Sector”, 2009• Identifier (id)
• http://education.data.gov.uk/id/school/121242 • Document (doc)
• http://education.data.gov.uk/doc/school/121242 • Representation
• http://education.data.gov.uk/doc/school/121242.html • http://education.data.gov.uk/doc/school/121242.rdf
• Definition / ontology (def)• http://education.data.gov.uk/def/school/
How it workshttp://education.data.gov.uk/id/school/121242 (ID URI)
Thing
Generic Document
http://education.data.gov.uk/doc/school/121242 (Doc URI)
RDF HTML
http://education.data.gov.uk/doc/school/121242.rdf http://education.data.gov.uk/doc/school/121242.html
303 redirect
ContentNegotiation
application/rdf+xml wins text/html wins
.../def/school (Def URI)
definition
Location URIs for the UK‘Spatial Thing’ http://ea.gov.uk/id
/HY/Watercourse/Thames
‘web document’http://ea.gov.uk/doc/HY/Watercourse/Thames
rdfs:seeAlso http://ea.gov.uk/so/HY/Watercourse/ea-UKrivers/e7w1rdfs:seeAlso http://geotod/so/HY/Watercourse/stfc-strategi/4a97ov:similarTo http://ceh.nerc/so/HY/Watercourse/nerc-hydrodb/thames-001
‘303 See other:’
‘Spatial Object’http://geotod/so/HY/Watercourse/stfc-strategi/4a97.rdf
http://geotod/so/HY/Watercourse/stfc-strategi/4a97.htmlhttp://geotod/so/HY/Watercourse/stfc-strategi/4a97.kmlhttp://geotod/so/HY/Watercourse/stfc-strategi/4a97.gml
‘content negotiation’
‘Id’ URI
‘Doc’ URI
‘So’ URI
GeoTOD-II
• Geospatial Transformation with OGSA-DAI
• Publish spatial data as linked data
• Conform to UK Cabinet Office recommendations
• Leverage existing related technologies
Requirements
Community Data Model/Vocabulary/Ontology
VS
http://domain/104014/5sfd/2442 http://domain/myserver/mydata
Existing data and GIS
services
Linked Data Service
Opaque URIsBespoke human-readable
URIs
How to interpret the guidelines?
Spatial Object
(SO URI)
Spatial Object
(SO URI)
Spatial Thing
(ID URI)
Spatial Thing Metadata (Doc URI)
???303 redirect
What info
Master Catalogue of
Spatial Objects
???Who owns it
???Register
Spatial Object
(SO URI)
How to represent the ontology?
• INSPIRE’s UML conceptual models• How to transform to OWL/RDF?• How to address import of ISO schemas? e.g.
• ISO 19107 (spatial schemas)• ISO 19115 (geospatial meta data)
• Unofficial and incomplete ontologies• UK Environmental Agency’s Bathing Water ontology• OGC GeoSPARQL working group
• Substantial tasks • Require involvement of the wider community
Converting UML to RDFS
http://tiger.dl.ac.uk:8080/rdfsgenerator
Existing linked data solutions
Existing open source linked data server products
UK Environmental Agency linked data server
(data.ordnancesurvey.co.uk)
Spanish geo-linked data server(geo.linkeddata.es)
Existing Linked-Data Services
Existing linked data solutions
• May not always have database access
• Limited scope for extending functionality– Add GIS service for GML-based data– Expose GML formats
• Need an extensible solution
GeoTOD-II linked data framework
OGSA-DAI SO store
Web resources
Relational resources
Linked SO
Store
OGSA-DAI service
Geotod-D2RQ
RDB
Workflow
Generate RDB-specific SQL using mapping file
SPARQL query+
output formatting
D2RQ Mappin
g File
SQL
GeoServer WS
GML query
GeoTOD prototype
• Test data• Ordnance Survey Strategi data set• UK natural and man-made features• ESRI shapefiles => SQL
• Ontology generation• Relevant INSPIRE models e.g. HY, TN• INSPIRE UML => XML Schema => RDFS• Easier than UML => RDFS direct
GeoTOD-II demo server
http://tiger.dl.ac.uk:8080/geotodls/index.html
Spatial thing HTMLhttp://tiger.dl.ac.uk:8080/id/TN/RailwayStationNode/heathrow-terminal-4-station
Spatial thing RDFhttp://tiger.dl.ac.uk:8080/id/TN/RailwayStationNode/heathrow-terminal-4-station
Spatial object GML http://tiger.dl.ac.uk:8080/so/TN/RailwayStationNode/tn-ra/984
Conclusions• GeoTOD framework
• Conforms to UK Cabinet Office location URIs• Plug-in support for new data sources or representations
• Should benefit projects and organisations looking to deploy existing geospatial data assets as linked data• Advanced Climate Research Infrastructure for Data
• http://www.cru.uea.ac.uk/cru/projects/acrid/index.htm
• Further work• Engage with linked data and geospatial communities• Develop into efficient and reliable product
• http://sourceforge.net/projects/geotod
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