Jun 24, 2010 - INSPIRE Conference. Krakow ... SDI based on INSPIRE requirements ... Based on OGC web services (CSW ISO A
Linked Data in SDI INSPIRE Conference Krakow, Poland, 24th June 2010 Simon Cox, EC DG Joint Research Centre, Ispra, Italy Sven Schade, EC DG Joint Research Centre, Ispra, Italy Clemens Portele, interactive instruments GmbH, Bonn, Germany
!
GEOSS (Global Earth Observation System of Systems) !
Built by the Group on Earth Observations (GEO) on the basis of a 10-Year Implementation Plan running from 2005 to 2015.
!
!
Seeks to connect together all existing Earth Observations resources and to make it easily accessible with the aim of support better decision making on 9 Societal Benefit Areas
INSPIRE Directive: establishing an Infrastructure for Spatial Information in the European Community (14 May 2007) !
Legislative instrument that lays down a general framework for a European Spatial Data Infrastructure (SDI) for the purposes of Community environmental policies and policies or activities which may have an impact on the environment. It builds upon National SDIs operated and maintained by European Member States
!
GMES (Global Monitoring for Environment and Security) !
GMES is a joint initiative of the European Commission and European Space Agency that consists of 3 components: !
Space Component that relies on existing or planned European space infrastructure (co-financed by the EU and ESA)
!
!
In-Situ Component that relies on facilities, instruments and services at national, regional and intergovernmental levels inside and outside the EU. Service component on Marine, Atmosphere, Land, Emergency, Security at pre-operational stage
© 2010 GIGAS Consortium http://www.thegigasforum.eu
SDI based on INSPIRE requirements !
!
!
Discovery, view and download services !
Based on OGC web services (CSW ISO AP, WMS, WFS, WCS, etc)
!
Probably straight HTTP for download of pre-packaged data sets, too
Access to data sets !
Published using an agreed semantics
!
GML currently the only encoding that has been specified
!
Other encodings are to be expected in the future, but not yet specified
!
Access to individual objects encouraged, but optional
Access to metadata for datasets and services !
!
Encoded according to the schema specified as part of CSW ISO AP
This includes key steps forward !
Availability of data over the internet
!
Distribution and delegation
© 2010 GIGAS Consortium http://www.thegigasforum.eu
Linked Data – in a nutshell !
Application of key web principles to ‘data’
Linked Data – key principles !
!
Be on the web !
Put your data on a server
!
Give it a Uniform Resource Locator (URL)
Associate your data with other data on the web !
!
Use hypertext, post links
Allow your data to be found !
Encourage others to link to it
!
Make it searchable
Linked Data – elaborations !
Add semantics !
!
Use Resource Description Framework (RDF) for links
Provide alternative representations: !
Navigation resources RDF for machines HTML for humans
! !
!
Data resources !
!
Other representations for specific applications
The Semantic Web (technology) meets the Deep Web (content)
Bonn 483 m2 …
Why do we care? (1) !
Linked data helps to use information from several sources
!
The mash-up effect
!
!
Make spatial and environmental data available
!
Can lead to unexpected and creative applications
New discovery, new applications !
(SPARQL) end-points support reasoning, inference, query-processing
Why do we care? (2) !
!
Open Government, PSI Directive in Europe !
data.gov, data.gov.uk includes the UK Location Program
!
Impacts NSDIs and thus INSPIRE
!
Strong backing including Tim Berners-Lee
!
See presentation by Keith Murray in this session
Shared Environmental Information System (SEIS) !
Reportnet (infrastructure to support the European Environment Agency, EEA, reporting obligations) builds on the concept of linked data
!
INSPIRE data is important input of (spatial) data into SEIS/Reportnet
INSPIRE / SDIs !
!
Datasets & objects – Identifiers !
INSPIRE identifiers (object)
!
Thematic identifiers (real-world thing)
Structured data – Semantics !
!
INSPIRE application schemas
Linking !
Object referencing recommendations in INSPIRE (Generic Conceptual Model)
!
Encoding !
!
GML (open for additional encodings)
Metadata !
ISO metadata will is available for data sets
INSPIRE / SDIs and linked data (1) Datasets & objects – Identifiers !
Identifiers not mandatory for all spatial objects in INSPIRE
!
Linked data requires stable Uniform Resource Identifiers (URIs) for every resource !
Should be http URIs that are resolvable
!
Requires a well-architectured URI scheme and good governance
!
Requires technical infrastructure so that the URIs can be resolved to representations of the resource
!
OGC is moving towards such stable http URIs for their resources !
Example: http://www.opengis.net/def/crs/EPSG/0/4326
© 2010 GIGAS Consortium http://www.thegigasforum.eu
INSPIRE / SDIs and linked data (2) Structured data – Semantics !
Semantics already specified in INSPIRE application schemas
!
UML (as used in INSPIRE) is largely isomorphic with RDF
© 2010 GIGAS Consortium http://www.thegigasforum.eu
INSPIRE / SDIs and linked data (3) Linking !
Object referencing and associations discussed in detail in INSPIRE Generic Conceptual Model
!
Supported in INSPIRE data specifications
!
However, today many spatial data sets do not represent or maintain links !
And if often only within the data set
© 2010 GIGAS Consortium http://www.thegigasforum.eu
INSPIRE / SDIs and linked data (4) Encoding !
GML is isomorphic with RDF !
rdf:about == gml:identifier
!
rdf:resource == xlink:href
!
This is not a coincidence…
!
GML documents are functionally both navigation + data resources!
!
Publication of data in other representations, too, so that data can be found/viewed/used by a number of applications
!
!
Navigation: HTML, RDF
!
Data: GML, KML, etc
The same applies to metadata!
Challenges !
!
Stable identifiers !
Linked data depends on http URIs
!
Governance of URIs for common resources must be orderly
!
Data URIs must be stable
!
URI patterns for customer-defined resources (e.g. subsets)
Linking !
!
!
Responsibilities for link establishment and maintenance to be identified
Available vocabularies & classifiers !
Semantics depends on shared ontologies, published as RDF
!
RDF API = SPARQL end-point
Infrastructure !
Content-negotiation getting implemented
!
Infrastructure to resolve URIs needs to be established and maintained
Conclusions !
SDI concepts and Linked Data do not exclude but complement each other
!
!
RDF allows for navigation, sophisticated querying and reasoning
!
GIS process GML and other geographic data encodings
SDIs should observe the developments in eGovernment and the web !
work on improving the integration of spatial data into the web
!
Linking data is a philosophy of usage and not a technical matter
!
Clear assessment of benefits still missing
!
For a more general discussion about related data interoperability issues see the GIGAS documents: !
D2.2b Data Interoperability Technical Note
!
D2.3b Comparative analysis report (loop 2)
Links to targeted Initiatives, Organisations and Projects:
Contact: Eva Klien
[email protected] http://www.thegigasforum.eu
© 2010 GIGAS Consortium http://www.thegigasforum.eu
The GIGAS Consortium
