Flagis linked open_data_stijn_goedertier

Spatial Data: where is the link?
FLAGIS Academic Session, Leuven, 12 May 2016
Stijn Goedertier

Linked Data design rules
HTTP GET http://dbpedia.org/resource/Tim_berners-lee Accept: "text/rdf+n3"
HTTP/1.1 303 See Other
Server: Virtuoso/07.20.3217 (Linux) i686-generic-linux-glibc212-64 VDB
Content-Type: text/rdf+n3
Location: http://dbpedia.org/data/Tim_berners-lee.nt
HTTP GET http://dbpedia.org/data/Tim_berners-lee.nt
HTTP/1.1 200 OK
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix wikipedia-en: <http://en.wikipedia.org/wiki/> .
@prefix dbr: <http://dbpedia.org/resource/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix prov: <http://www.w3.org/ns/prov#> .
wikipedia-en:Tim_berners-lee foaf:primaryTopicdbr:Tim_berners-lee .
dbr:Tim_berners-lee owl:sameAs <http://rdf.freebase.com/ns/m.07d5b> .
dbr:Tim_berners-lee rdfs:label "Tim berners-lee"@en ;
foaf:isPrimaryTopicOf wikipedia-en:Tim_berners-lee .
dbr:Tim_berners-lee prov:wasDerivedFrom
<http://en.wikipedia.org/wiki/Tim_berners-lee?oldid=291475851> .

HTTP/1.1 200 OK
1. Use URIs as names for things
2. Use HTTP URIs so that people can look up those
names.

HTTP/1.1 200 OK
1. Use URIs as names for things
2. Use HTTP URIs so that people can look up those
names.
3. Provide useful information, using the
standards (RDF*, SPARQL), when
someone looks up a URI.
4. Include links to other URIs so that
they can discover more things.

Not all Linked Data is Open Data…
Open data is data available under an open licence (open
data and content can be freely used, modified, and
shared by anyone for any purpose e.g. CC0)
[OpenDefinition]
There is also Linked Closed Data, e.g. for privacy or
commercial reasons.

What is special about spatial data?
Spatial data is data about spatial things represented as
objects using classes, properties, and relationships.
A spatial object can have:
- geo-name: Leuven
- address: Philipssite 5 Bus 27 3001 Leuven
- geometry: POINT(4.7135173 50.8669778 )
POLYGON(4.6894703 50.944070
7, 4.6897756 50.9439115,
4.6903806 50.9436067,
4.690979 50.9432192, …)
Administrative Boundary Leuven © OpenStreetMap contributors, available under the Open Database licence

In RDF
@prefix geo: <http://www.opengis.net/ont/geosparql#> .
@prefix sf: <http://www.opengis.net/ont/sf#>.
@prefix locn: <https://www.w3.org/ns/locn#> .
@prefix kbo: <http://data.kbodata.be/organisation/> .
@prefix statbel: <http://location.testproject.eu/so/au/AdministrativeUnit/STATBEL/>.
kbo:0454_064_819 a rov:RegisteredOrganization;
rdfs:label "G.I.M - Geographic Information Management";
locn:address :gimAddress;
geo:hasGeometry :gimPoint.
:gimPoint a sf:Point;
geo:asWKT "POINT(50.8669778 4.7135173)"^^geo:wktLiteral.
:gimAddress a locn:Address
locn:fullAddress "Philipssite 5 Bus 27 3001 Leuven";
locn:geometry :gimPoint.
statbel:24062 a locn:GeographicName;
rdfs:label "Leuven";
geo:hasGeometry :leuvenPolygon.
:leuvenPolygon a sf:Polygon;
geo:asWKT "POLYGON(4.6894703 50.9440707, 4.6897756 50.9439115,
4.6903806 50.9436067, 4.690979 50.9432192, …)"^^geo:wktLiteral.

Spatial Data Infrastructures
… and the Web
▶ Spatial Data Infrastructures: for experts
• Rich APIs: OGC CSW, WMS, WFS, …
• Rich representations: GML, …
• Many Coordinate Reference Systems

Spatial Data Infrastructures
… and the Web
▶ Spatial Data Infrastructures: for experts
• Rich APIs: OGC CSW, WMS, WFS, …
• Rich representations: GML, …
• Many Coordinate Reference Systems
▶ Linked Spatial Data: for Web developers
• Simple APIs: HTTP, (SPARQL)
• Simple representations: GeoJSON, RDF,
GeoSPARQL, …
• Fewer Coordinate Reference Systems:
WGS84

Spatial standards and the Web
1989: Word Wide Web
1991: HTTPv0.9
1999: W3C RDF
2006: Linked Data Design Rules
2008: KML
2008: GeoJSON
2009: OGC GeoSPARQL
2012: ISA Core Location
2013: Annex on URIs in INSPIRE
2014: INSPIRE as Linked Data
2014: OGC/W3C Spatial Data on the Web
2008: W3C SPARQL
2007: OGC GML
1995: IETF HTML 2.0
2000: HTTPv1.1
2000: ReST
1999: OGC WKT (SQL)
WebStandardsSpatialDataStandards
2002: OGC WFS

GeoDCAT-AP
The geospatial community use mature standards for
descriptive metadata (ISO19115) and discovery services
(OGC CSW) …
… but open data portals speak DCAT-AP.
GeoDCAT-AP indicates how geo-
metadata records can be encoded in
DCAT-AP.
Translation from ISO19115 to
GeoDCAT-AP implemented using
XSLT and embedded in GeoNetwork.
A large majority of datasets on open
data portals are spatial data.

Generic use cases for linked spatial data
Identifier
(HTTP URI)
Name or
Address
Look up: get data
from a URI such as the
name or address of a
feature
Identify (reconcile,
disambiguate) an
address notation
Link datasets by means
of commonly used
identifiers
Example:
Chaussée de Bruxelles 135
1310 La Hulpe
Example:
http://location.testproject.
eu/so/ad/AddressRepresen
tation/SPW/248565
50.8672312,4.7127429
Geometry
Reverse geocode
find feature(s) based on
a location
Geocode retrieve the
location(s) of a feature
expressed as a geometry
Locate objects by
comparing their relative
geometric positions
Linked DataSpatial Data

Example: Linked Address Data
OpenLink Virtuoso
UrBIS - Brussels
Capital Region
CRAB - Flanders PICC - Wallonia
DATA CONSUMER
sample address data in native format
Linked address data
Common Data models
RDF view
SPARQL endpoint
INSPIRE
lookup, identify, link, locate, geocode,
reverse gecode
XML view
Xquery,
Xpath
• XML and RDF
views on
relational data
served over a
Web interface
http://location.testproject.eu/BEL/

Use case: identify
Identify: Reconcile or disambiguate a name or
address.

Use case: lookup
GIM - linked spatial data: where is the link?
Lookup: Retrieve structured data from a URI in
various formats.

Use case: lookup
GIM - linked spatial data: where is the link?
Lookup: Retrieve structured data from a URI in
various formats.
GET http://location.testproject.eu/so/au/AdministrativeUnit/STATBEL/25050
Accept: "application/rdf+xml"
Server: Virtuoso/07.10.3207 (Linux) x86_64-pc-linux-gnu
Date: Mon, 09 May 2016 14:15:22 GMT
Location: http://location.testproject.eu/doc/au/AdministrativeUnit/STATBEL/25050.rdf
GET http://location.testproject.eu/so/au/AdministrativeUnit/STATBEL/25050
Accept: "application/gml+xml"
Server: Virtuoso/07.10.3207 (Linux) x86_64-pc-linux-gnu
Date: Mon, 09 May 2016 14:15:23 GMT
Location: http://location.testproject.eu/doc/au/AdministrativeUnit/STATBEL/25050.xml

Use case: locate – implicit links
Locate spatial objects by comparing their relative
geometric positions. (Spatial data is implicitly linked
without URIs!)
Topological relations:
:A geo:sfEquals :B. :A geo:sfDisjoint :B
:A geo:sfContains :B:B geo:sfOverlaps :A
A geo:sfTouches :B

Use case: locate
GeoSPARQL query: which companies are within the
administrative boundaries of Leuven?
PREFIX geo: <http://www.opengis.net/ont/geosparql#>
PREFIX rov: <http://www.w3.org/ns/regorg#>
SELECT ?company
WHERE {
?company a rov:RegisteredOrganization;
geo:hasGeometry ?cgeo .
statbel:24062 geo:hasGeometry ?leuvenPolygon .
?cgeo geo:sfWithin ?leuvenPolygon .
}

Use case: link
Link: Link two datasets on the basis of common
identifiers.

BelMap GeoDaaS
GIMs BelMap GeoDaaS platform offers linked data on
Belgian addressable objects with persistent identifiers.
Used within the COMBUST ICONProject (Funded by
iMinds, IWT and Innoviris.) for linking data on
businesses.

Revenue models for Linked Data?
• Public funding: governments publish linked open
data to grow the data economy and bring social
benefits.
• Advertisement: being paid for online advertisements
on generated traffic.
• Subscription: being paid by a user base of
professional clients. Often using a freemium pricing
model.

Index structured data from the Web using
e.g. Schema.org annotated content
Lots of spatial data modelling in
schema.org:
• schema:Place
• schema:AdministrativeArea
• schema:LocalBusiness
• …
• schema:StruturedValue
• schema:PostalAddres
• schema:GeoCoordinates
• schema:GeoShape

Where is the link?
Linked Data requires stable interfaces.
App developers will only rely on Web identifiers of
others if they provide credible service level
guarantees...

How to publish linked spatial data?
Continually improve the quality of your data
Find the right licence and funding model
Define persistent URIs
Use a stable vocabulary
Reuse existing infrastructure (e.g. WFS)
You don’t need a public SPARQL endpoint 

Stijn Goedertier
GeoICT Project Manager
stijn.goedertier@gim.be
Steven Smolders
Technology Director
steven.smolders@gim.be
Thank you!

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