The ICAN CSW Mediator
Yassine Lassoued
[email protected]
Omar Boucelma
[email protected]
Dawn Wright
[email protected]
Luis Bermudez
[email protected]
Outline
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
•
•
•
•
•
•
•
•
•
•
•
•
•
Introduction
ICAN
Problem
Terminology
Idea
Approach
Architecture
Ontologies
Ontologies Mappings
Query Rewriting
Demonstration
Conclusion
Future Work
JIGOT’08 – Marseille
2
Introduction
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Demonstrate how ontologies and
standards can be used to:
– Help geographic information systems
interoperate
– Improve data discovery
– Facilitate resources sharing
• Conclusion
• Future Work
November 2008
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ICAN
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
• International Coastal Atlas Network
• Network of scientists, organisations
and institutions with interest in the
coastal and marine domain
• Objective
– Build and strengthen atlas networks
– Develop an internationally-enabled
coastal Web atlas (CWA)
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ICAN
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
• More than 30 members from more
than 12 countries:
– Coastal and Marine Resources Centre
– Oregon State University
– European Environmental Agency
– Marine Metadata Interoperability
– International Oceanographic Data and
Information Exchange
– Marine Institute
– Etc.
JIGOT’08 – Marseille
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Problem
• Interoperability of
distributed autonomous
and heterogeneous
coastal Web atlases
(CWA)
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
…
November 2008
JIGOT’08 – Marseille
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Problem
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Coastal Web Atlas (CWA):
– Web application for the delivery of coastal
resources such as:
•
•
•
•
Geographic datasets
Maps
Metadata
Thematic (educational) information
• Future Work
November 2008
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Problem
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Heterogeneity:
– Syntactic (data formats, query languages)
– Structural (data schemas)
– Semantic (meaning of data values)
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
 E.g.:
 Metadata:
– Different metadata standards (ISO vs. FGDC)
– Different terms: ‘Seabed’ vs. ‘Seafloor’
‘Coastline’ vs. ‘Shoreline’
November 2008
JIGOT’08 – Marseille
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Terminology
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
• OGC Web Service:
– OGC specification
– Interface allowing requests for geographic
“resources” across the Web using
platform-independent calls
– Main OGC services:
•
•
•
•
Catalogue Service for the Web (CSW)
Web Feature Service (WFS)
Web Coverage Service (WCS)
Web Map Service (WMS)
JIGOT’08 – Marseille
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Terminology
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• OGC Web Service:
– Catalogue Service for the Web (CSW)
• Allows requests for metadata across the Web
• E.g. GeoNetwork is a CSW implementation
• Architecture
• Ontologies
• Mappings
Request
Response
Get Capabilities
Metadata about the types / operations the CSW
supports
Get Records
Metadata records available, with possibility of
filtering (bounding box, spatial, temporal,
keywords search, etc.)
Get Record By ID
Record with the specified ID
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
JIGOT’08 – Marseille
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Terminology
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
• Ontologies:
– A Knowledge Organisation System (KOS)
– Define concepts (classes and objects)
– Define relationships between concepts
– Define inference rules
– Examples:
•
•
•
•
John is a Person
Mary is a Person
Mary is mother of John
If (X is father of Y & Y is father of Z)
then X is grand-father of Z
JIGOT’08 – Marseille
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Terminology
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Mediation:
– A virtual data integration approach
– Allows transparent access and integration of
autonomous distributed heterogeneous data
sources
• Architecture
• Ontologies
• Mappings
• Query Rewriting
Query
• Demonstration
Same data structure
Same semantics
Response
Mediator
• Conclusion
• Future Work
November 2008
Same query language
Same data model and format
Wrapper
Wrapper
Oracle
DB
Access
DB
JIGOT’08 – Marseille
Wrapper
Text
Heterogeneous data sources
12
Idea
• Outline
• Introduction
• ICAN
• Problem
• Connect individual coastal atlases to an
integrated global atlas
• Terminology
• Idea
• Approach
Global atlas
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
Local atlases
…
November 2008
JIGOT’08 – Marseille
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Approach
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
• Centralised system
 Resources are accessed through one
central system (ICAN global atlas)
• Virtual integration approach
 Data are not copied into the global
Atlas
• Local atlases autonomy
 Each data atlas is autonomous and
organises resources in its own way and
uses its own terminology (ontology)
November 2008
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Approach
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
•
To achieve interoperability:
1. Harmonisation:
•
Harmonise access interfaces and resource
formats
– Implement OGC Web Services
» Catalogue Service for the Web (CSW)
» Web Feature Service (WFS)
» Web Coverage Service (WCS)
» Web Map Service (WMS)
– Use ISO metadata standards
» ISO-19115 & ISO-19139
 Harmonise Web querying and delivery formats
November 2008
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Approach
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
•
To achieve interoperability:
2. Mediation:
•
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
•
• Demonstration
• Conclusion
• Future Work
November 2008
•
Allow local atlases to use their own data
structures, semantics and vocabularies
(ontologies)
Use a common data structure and a
common ontology for the global atlas
Provide mappings (translations) between
local ontologies and the global ontology
JIGOT’08 – Marseille
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Approach
• Outline
• Introduction
Harmonisation vs. Mediation
• ICAN
• Problem
• Terminology
ICAN
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
Mediation
• Query Rewriting
Mediation
• Demonstration
• Conclusion
• Future Work
Mediation
Mediation
Harmonisation
Harmonisation
Harmonisation
Harmonisation
November 2008
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Approach
• Outline
• Introduction
•
We focus on Metadata interoperability
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
“Seabed
”
• Conclusion
• Future Work
ISO Metadata
&
MIDA terminology
November 2008
JIGOT’08 – Marseille
“Seafloor
”
FGDC Metadata
&
OCA terminology
…
Atlas X
X Standard
&
X terminology
18
Architecture
• Outline
• Introduction
• ICAN
Mapping Example:
• Problem
• Terminology
ICAN:Coastline
ICAN Ontology
• Idea
• Approach
• Architecture
• Ontologies
Inference
Engine
is similar to
Virtual CSW
OCA:Shoreline
Mappings
• Mappings
• Query Rewriting
• Demonstration
MIDA Ontology
OCA Ontology
X Ontology
• Conclusion
• Future Work
CSW
CSW
CSW
…
November 2008
JIGOT’08 – Marseille
X
19
Local and Global Ontologies
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• A global ontology represents the
keywords used in the virtual ICAN
catalogue service
• For each atlas X, a local ontology
represents the keywords used by the X
catalogue service
• Demonstration
• Conclusion
• Future Work
November 2008
• Five types of keywords (ISO-19115):
Theme, Discipline, Place, Temporal,
Stratum
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Local and Global Ontologies
• Outline
• Introduction
Local Ontology (OCA)
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
Global Ontology
November 2008
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Ontology Mappings
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
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Ontology Mappings
• Outline
• Introduction
• ICAN
• Problem
MIDA Mappings
OCA Mappings
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
Each mappings file is an OWL ontology
November 2008
JIGOT’08 – Marseille
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Query Rewriting
• Outline
• Introduction
• ICAN
• Problem
• Rewrite user’s request into requests
supported by local CSWs
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
JIGOT’08 – Marseille
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Query Rewriting
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
http://ican.ucc.ie/srv/en/csw?request=GetRecords&service=CSW&version=2.0.1
&resultType=results&namespace=csw:http://www.opengis.net/cat/csw&maxRecords=1000
&elementSetName=summary
&constraint=
<?xml version="1.0" encoding="UTF-8"?>
<Filter xmlns=http://www.opengis.net/ogc xmlns:gml=http://www.opengis.net/gml
xmlns:csw="http://www.opengis.net/cat/csw/2.0.2">
<And>
<PropertyIsLike wildCard="%“ singleChar="_" escape="\">
<PropertyName>keyword</PropertyName>
<Literal>HumanResponsesToCoastalChange%</Literal>
</PropertyIsLike>
<BBOX>
<PropertyName>/csw:Record/ows:BoundingBox</PropertyName>
<gml:Envelope srsName="http://www.opengis.net/gml/srs/epsg.xml#4326">
<gml:lowerCorner>-180 -90</gml:lowerCorner>
<gml:upperCorner>180 90</gml:upperCorner>
</gml:Envelope>
</BBOX>
</And>
</Filter>
&constraintLanguage=FILTER
&constraint_language_version=1.1.0
JIGOT’08 – Marseille
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Query Rewriting
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
http://ican.ucc.ie/srv/en/csw?request=GetRecords&service=CSW&version=2.0.1
&resultType=results&namespace=csw:http://www.opengis.net/cat/csw&maxRecords=1000
&elementSetName=summary
&constraint=
<?xml version="1.0" encoding="UTF-8"?>
<Filter xmlns=http://www.opengis.net/ogc xmlns:gml=http://www.opengis.net/gml
xmlns:csw="http://www.opengis.net/cat/csw/2.0.2">
<And>
<PropertyIsLike wildCard="%“ singleChar="_" escape="\">
<PropertyName>keyword</PropertyName>
<Literal>HumanResponsesToCoastalChange%</Literal>
</PropertyIsLike>
<BBOX>
<PropertyName>/csw:Record/ows:BoundingBox</PropertyName>
<gml:Envelope srsName="http://www.opengis.net/gml/srs/epsg.xml#4326">
<gml:lowerCorner>-180 -90</gml:lowerCorner>
<gml:upperCorner>180 90</gml:upperCorner>
</gml:Envelope>
</BBOX>
</And>
</Filter>
&constraintLanguage=FILTER
&constraint_language_version=1.1.0
JIGOT’08 – Marseille
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Query Rewriting
• Outline
• Introduction
Mediator uses inference engine to translate global terms into local terms
• ICAN
• Problem
MIDA Mappings
OCA Mappings
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
JIGOT’08 – Marseille
27
Query Rewriting
• Outline
• Introduction
• ICAN
• Problem
• Terminology
Global
<PropertyIsLike wildCard="%“ singleChar="_" escape="\">
<PropertyName>keyword</PropertyName>
<Literal>HumanResponsesToCoastalChange%</Literal>
</PropertyIsLike>
• Idea
• Approach
• Architecture
MIDA
• Ontologies
• Mappings
<Or>
<PropertyIsLike wildCard="%“ singleChar="_" escape="\">
• Query Rewriting
<PropertyName>keyword</PropertyName>
<Literal>CoastalProtection%</Literal>
• Demonstration
• Conclusion
</PropertyIsLike>
<PropertyIsLike wildCard="%“ singleChar="_" escape="\">
• Future Work
<PropertyName>keyword</PropertyName>
<Literal>CoastalDefenceStructure%</Literal>
</PropertyIsLike>
</Or>
November 2008
JIGOT’08 – Marseille
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Demonstration
• Outline
• Introduction
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
• Ontologies
http://ican.ucc.ie
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
JIGOT’08 – Marseille
29
Conclusion
• Outline
• Introduction
•
• ICAN
• Problem
• Terminology
• Idea
• Approach
• Architecture
•
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
•
• Conclusion
• Future Work
November 2008
•
Efficient solution for facilitating
syntactic, structural and semantic
interoperability
A system that can be integrated as a
node within another mediated system
Ontologies and standards facilitate
interoperability
This is a first step in atlases
interoperability focusing only on
metadata and catalogue services
JIGOT’08 – Marseille
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Future Work
• Outline
• Introduction
•
• ICAN
• Problem
• Terminology
• Idea
• Approach
•
• Architecture
• Ontologies
• Mappings
• Query Rewriting
• Demonstration
• Conclusion
• Future Work
November 2008
•
Include Web Map Service (WMS) for
data visualisation
Include Web Feature Service (WFS)
& Web Coverage Service (WCS) for
actual data delivery
Share resources (thematic
information about layer)
JIGOT’08 – Marseille
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Future Work
• Outline
• Introduction
• ICAN
Mapping Example:
• Problem
• Terminology
ICAN:Coastline
ICAN Ontology
• Idea
is similar to
• Approach
• Architecture
• Ontologies
OCA:Shoreline
Mappings
• Mappings
• Query Rewriting
• Demonstration
MIDA Ontology
OCA Ontology
X Ontology
• Conclusion
• Future Work
CSW
WMS
WFS
CSW
WMS
WFS
CSW
…
November 2008
JIGOT’08 – Marseille
WMS
WFS
X
32
Thank You
Terminology
• OGC Web Service:
– Web Feature Service (WFS)  Vector data
• Allows requests for geographic features across the Web
• E.g. GeoServer, Deegree are WFS implementations
November 2008
Request
Response
Get Capabilities
Metadata about the types / operations the WFS
supports
Describe Feature
Structural information about a feature type
Get Feature
Features, with possibility of spatial querying and
filtering
JIGOT’08 – Marseille
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Terminology
• OGC Web Service:
– Web Coverage Service (WCS)  Raster data
• Allows requests for grid data across the Web
• E.g. GeoServer, Deegree implement WCS
November 2008
Request
Response
Get Capabilities
Metadata about the types / operations the WCS
supports
Describe Coverage
Structural information about one or more
coverage(s)
Get Coverage
Coverage data from the server, with possibility of
spatial querying and filtering
JIGOT’08 – Marseille
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Terminology
• OGC Web Service:
– Web Map Service (WMS)  Maps
• Allows requests for maps across the Web
• E.g. UMN MapServer is a WMS
November 2008
Request
Response
Get Capabilities
Metadata about the types / operations the WMS
supports
Get Map
Map of the requested data
Get Feature Info
Thematic information about a particular point
within a map
JIGOT’08 – Marseille
36
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