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< MMI />. Ontology Semantic Mediation in the Big Picture. MMI Workshop - August 2005. Semantic Issues. What is the meaning ?. How are the terms related ?. Data. Metadata. http://www.ws-i.org/img/juggler.gif. Information systems talk different languages. Community agreements. - PowerPoint PPT Presentation
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<<MMIMMI /> />Ontology Semantic Mediation Ontology Semantic Mediation
in the Big Picturein the Big Picture
MMI Workshop - August 2005
Semantic IssuesSemantic Issues
http://www.ws-i.org/img/juggler.gif
What is the meaning ? How are the terms related ?
DataMetadata
Information systems talk Information systems talk different languagesdifferent languages
Community agreementsCommunity agreements
Metadata Data
EML
ISO ADL
DCMI
FGDC
MARINE XML
GML
ADL
NetCDDF
ASCII
Content
Protocol
ESML
OPenDAP
RestSOAPZ39.50
DFDL
MMI Demo for Demo Agreement
What do we want to achieve ?What do we want to achieve ?User searches for:
Source type
(Platform/Sensor/ instrument/model)
Lat Long Depth Time (Z) Latest value (units)
Link to Metadata and data
category
label_of_source
Sea Temperature
Salinity
Nitrate
Phosphate
Oxygen
Silicate
…
BOG
SSDS
AOSN
ROV
World Ocean Data Atlas
CIMT
PFEL
FLIT NUMERICAL MODEL
…
MMI Demo for DemoMMI Demo for DemoWSDL SourceWSDL Source
Metadata in DCMIMetadata in DCMI
MMI Demo for DemoMMI Demo for DemoWSDL SourceWSDL Source
MMI ASCIIMMI ASCII• Is in ASCII• Field delimiter = tab• Record delimiter = "\n" (line feed)• Has one header line, with the variable names and units, units in parenthesis.• Order of the columns is: time depth lat long variableName. time(YYYY-MM-DDThh:mm:ss) depth(meters) lat(degrees) lon(degrees) Temperature_8(deg C)
•If no units, then "()".• Lat long are in degrees.• Show "-" before the coordinate values for south east coordinates• For dateTime always use T to separate them.• Format of time is: YYYY-MM-DDThh:mm:ss±hh:mm or YYYY-MM-DDThh:mm:ss±hh. •Missing values write "null" in lowercaps•…
So far looks good, soSo far looks good, so
where do we have where do we have semantic mediation semantic mediation
problems ?problems ?
Need more than an agreement on a Need more than an agreement on a metadata specification. Why ?metadata specification. Why ?
Could all of these be
discovered?
Search for sea temperature
data
TCNTTCMF (BODC)
Metadata repositorykeyword value
sea surface temperature (GCMD)
sea water temperature (CF)
Needed controlled vocabulariesNeeded controlled vocabularies
UnitsParametersPhenomenaModelsSensorsInstrumentsFormatsOrganizationsGeographic PlacesDatumsSpecies categories etc …
Controlled vocabularies serve Controlled vocabularies serve different purposesdifferent purposes
Discovery Vocabulary Terms people use to search (discover) data. Systems that use these terms, know how to link with usage terms embeded in data repositories. e.g. ocean temperature
Usage VocabularyTerms people use when cataloging data. Most of the times have units associated. Systems that used this terms, know how to manage it. e.g. temp3 or TCNTTCMF
Strategies to solve semantic Strategies to solve semantic interoperability issuesinteroperability issues
• Make general agreement about one and only one controlled vocabulary.
• Accept that more than one vocabulary exists, and try to mediate across them.
Middle way solution:• Try to establish an agreed preferred
controlled vocabulary and create mappings to and from this vocabulary.
How are the agreements of controlled How are the agreements of controlled vocabularies expressed vocabularies expressed
and implemented ?and implemented ?
• Expressed in HTML files, CSV, word documents etc…
• Implemented embedding the semantics in software programs (Hardcoded).
MMI StrategyMMI StrategyFaciliate semantic mediationFaciliate semantic mediation
• Harmonization strategies
• Mapping tools
• Vocabulary web services
• Semantic mediation in discovery services
Guides for HarmonizationGuides for Harmonization
DTDDTD
Comma Comma Separated Separated
ValuesValues
HTMLHTML
Tab Tab Separated Separated
ValuesValues
Relational Relational DatabaseDatabase
XML/XSDXML/XSD
RDFRDF
OWLOWL
Ontologies RepositoryOntologies Repository
Mapping ToolsMapping Tools
Web servicesWeb services
1) Vocabulary Harmonization
2) Vocabulary Mapping
3) Vocabulary Services
4) Access to Data
Demonstration Demonstration Ontology metadata mediationOntology metadata mediation
Demo Demo Ontology metadata mediationOntology metadata mediation
http://marinemetadata.org/2005/06/ssds#Temperature_8http://marinemetadata.org/2005/06/ssds#Temperature_3http://marinemetadata.org/2005/06/ssds#Temperature_1http://marinemetadata.org/2005/06/ssds#Temperature_5http://marinemetadata.org/2005/06/ssds#Temperature_7http://marinemetadata.org/2005/06/ssds#isusTemphttp://marinemetadata.org/2005/06/aosn#sea_surface_temperaturehttp://marinemetadata.org/2005/06/ssds#Temperature_2http://marinemetadata.org/2005/06/ssds#Temperature_9http://marinemetadata.org/2005/06/ssds#Temperature_6http://marinemetadata.org/2005/06/ssds#Temperature_4http://marinemetadata.org/2005/06/ssds#temp_0http://marinemetadata.org/2005/06/ssds#temp_0mhttp://marinemetadata.org/2005/02/gcmd#Ocean_Temperaturehttp://marinemetadata.org/2005/02/gcmd#Sea_Surface_Temperaturehttp://marinemetadata.org/2005/06/aosn#ocean_temperature
Ontology metadata mediationOntology metadata mediation
Searching “sameAs” and “narrowerThan” for Ocean TemperatureLoading model http://localhost:9600/ont/map-aosn-ssds-gcmd.Found ssds:Temperature_8 and sea_surface_temperature
Searching ontology http://marinemetadata.org/2005/06/ssdsFound corresponding WSDL for SSDS http://ssds.shore.mbari.org:8080/axis/services/DataProducercalling the web service searching Temperature_8Number of results added: 4
Searching ontology http://marinemetadata.org/2005/06/aosnFound corresponding WSDL http://mammoth.shore.mbari.org:8080/axis/services/DataProducercalling the web service searching sea_surface_temperatureNumber of results added: 9
Ontology metadata mediationOntology metadata mediationtemperature_8
water temperature from unit 00661Identifier is: urn:ssds.mbari.org.recordVariable.id:243490
water temperature from unit 00829Identifier is: urn:ssds.mbari.org.recordVariable.id:141923…
Sea Surface Temperature
Observation Data/Drifters/MBARI Drifter 4 (8/11-9/5/2003)/Sea Surface Temperature (count=190)Identifier is: urn:aosn.mbari.org.recordVariable.i.id:243483
Observation Data/Aircraft/Sea Surface Remote Sensing and Atmospheric Meteorology (8/4-6,10-11,13,15,20-22,25,29,9/4-5,6/2003)/Sea Surface Temperature (count=148538)Identifier is: urn:aosn.mbari.org.recordVariable.id:44
ConclusionsConclusions
• Controlled vocabulary is an open issue. It should be addressed and agreements must take place.
• Impossible to reach one and only one agreement, mapping and mediation should be part of the interoperable systems.
• Follow standards as much as possible• Tools and more tools are needed.
<<MMIMMI /> />OntologiesOntologies
MMI Workshop - August 2005
Ontologies Specification of conceptualizations
Body of Water Class
RiverLake
Has water
Is inland body
Has a relative defined channel
Lake RiverExample:1. Properties of real
world objects are identified.
2. Similarities are identified.
3. Concepts are created…
4. and are expressed as a class.
5. Classes are related.
Subclass
Web Ontology Language: OWL
<owl:Class rdf:ID=“Body_of_Water”></owl:Class>
<owl:Class rdf:ID=“River”> <rdfs:subClassOf rdf:resource=“# Body_of_Water”/></owl:Class>
• W3C Recommendation 02/04.• Based on RDF. (-> URI )• Inference capabilities.• Restriction of inherit properties.• Can be used to express
specifications and vocabularies
Body of Water
River
Hydrologic Unit
Region Subregion Accounting Unit
Cataloging Unit
Is part of
Mid Atlantic
Delaware
Lower Delaware Schuylkill
Is part of
Is part of
Is part of
Vocabularies expressed in ontologies
Subclasses
Is Transitive
Infer isPartOf
ClassLooks like a Real world objects
Instances
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