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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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  • Ontology Semantic Mediation in the Big PictureMMI Workshop - August 2005

  • Semantic Issueshttp://www.ws-i.org/img/juggler.gifWhat is the meaning ?How are the terms related ?DataMetadata

  • Information systems talk different languages

  • Community agreementsMetadataDataEMLISOADLDCMIFGDCMARINE XMLGMLADLNetCDDFASCIIContentProtocolESMLOPenDAPRestSOAPZ39.50DFDLMMI Demo for Demo Agreement

  • What do we want to achieve ?User searches for:Sea TemperatureSalinityNitratePhosphateOxygenSilicateBOGSSDSAOSNROVWorld Ocean Data AtlasCIMTPFELFLIT NUMERICAL MODEL

    Source type(Platform/Sensor/ instrument/model)

    LatLongDepthTime (Z)Latest value (units)Link to Metadata and datacategory label_of_source

  • MMI Demo for DemoWSDL Source

  • Metadata in DCMI

  • MMI Demo for DemoWSDL Source

  • MMI 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:sshh:mm or YYYY-MM-DDThh:mm:sshh. Missing values write "null" in lowercaps

  • So far looks good, so

    where do we have semantic mediation problems ?

  • Need more than an agreement on a metadata specification. Why ?Could all of these be discovered?Search for sea temperature dataTCNTTCMF (BODC)Metadata repositorykeyword valuesea surface temperature (GCMD)sea water temperature (CF)

  • Needed controlled vocabulariesUnitsParametersPhenomenaModelsSensorsInstrumentsFormatsOrganizationsGeographic PlacesDatumsSpecies categories etc

  • Controlled vocabularies serve different purposesDiscovery 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 interoperability issuesMake 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 vocabularies expressed and implemented ?Expressed in HTML files, CSV, word documents etc

    Implemented embedding the semantics in software programs (Hardcoded).

  • MMI StrategyFaciliate semantic mediation Harmonization strategies Mapping tools Vocabulary web services Semantic mediation in discovery services

  • Guides for HarmonizationDTDComma Separated ValuesHTMLTab Separated ValuesRelational DatabaseXML/XSDRDFOWL

  • Ontologies Repository

  • Mapping Tools

  • Web services

  • 1) Vocabulary Harmonization2) Vocabulary Mapping 3) Vocabulary Services4) Access to DataDemonstration Ontology metadata mediation

  • Demo Ontology metadata mediationhttp://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 mediationSearching 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 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

  • ConclusionsControlled 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 possibleTools and more tools are needed.

  • OntologiesMMI Workshop - August 2005

  • Ontologies Specification of conceptualizationsBody of WaterClassRiverLakeHas waterIs inland bodyHas a relative defined channelExample:Properties of real world objects are identified.Similarities are identified. Concepts are createdand are expressed as a class.Classes are related.Subclass

  • Web Ontology Language: OWL

    W3C Recommendation 02/04. Based on RDF. (-> URI ) Inference capabilities. Restriction of inherit properties. Can be used to express specifications and vocabulariesBody of WaterRiver

  • Hydrologic UnitMid AtlanticDelawareLower Delaware SchuylkillVocabularies expressed in ontologiesSubclassesInstances