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< MMI />

< 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.

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  1. <MMI /> Ontology Semantic Mediation in the Big Picture MMI Workshop - August 2005

  2. Semantic Issues What is the meaning ? How are the terms related ? Data Metadata http://www.ws-i.org/img/juggler.gif

  3. Information systems talk different languages

  4. Community agreements Metadata Data Content ISO ADL FGDC NetCDDF GML DFDL MARINE XML EML ASCII DCMI ESML ADL Protocol OPenDAP Z39.50 Rest SOAP MMI Demo for Demo Agreement

  5. What do we want to achieve ? BOG SSDS AOSN ROV World Ocean Data Atlas CIMT PFEL FLIT NUMERICAL MODEL … User searches for: Sea Temperature Salinity Nitrate Phosphate Oxygen Silicate …

  6. MMI Demo for Demo WSDL Source

  7. Metadata in DCMI

  8. MMI Demo for Demo WSDL Source

  9. 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:ss±hh:mm or YYYY-MM-DDThh:mm:ss±hh. • Missing values write "null" in lowercaps • …

  10. So far looks good, so where do we have semantic mediation problems ?

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

  12. Needed controlled vocabularies UnitsParametersPhenomenaModelsSensorsInstrumentsFormatsOrganizationsGeographic PlacesDatumsSpecies categories etc …

  13. Controlled vocabularies serve different 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 temperatureUsage 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

  14. Strategies to solve semantic interoperability 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.

  15. 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).

  16. MMI Strategy Faciliate semantic mediation • Harmonization strategies • Mapping tools • Vocabulary web services • Semantic mediation in discovery services

  17. Guides for Harmonization HTML Comma Separated Values Tab Separated Values DTD OWL XML/XSD Relational Database RDF

  18. Ontologies Repository

  19. Mapping Tools

  20. Web services

  21. Demonstration Ontology metadata mediation 1) Vocabulary Harmonization 2) Vocabulary Mapping 3) Vocabulary Services 4) Access to Data

  22. Demo Ontology metadata mediation http://marinemetadata.org/2005/06/ssds#Temperature_8 http://marinemetadata.org/2005/06/ssds#Temperature_3 http://marinemetadata.org/2005/06/ssds#Temperature_1 http://marinemetadata.org/2005/06/ssds#Temperature_5 http://marinemetadata.org/2005/06/ssds#Temperature_7 http://marinemetadata.org/2005/06/ssds#isusTemp http://marinemetadata.org/2005/06/aosn#sea_surface_temperature http://marinemetadata.org/2005/06/ssds#Temperature_2 http://marinemetadata.org/2005/06/ssds#Temperature_9 http://marinemetadata.org/2005/06/ssds#Temperature_6 http://marinemetadata.org/2005/06/ssds#Temperature_4 http://marinemetadata.org/2005/06/ssds#temp_0 http://marinemetadata.org/2005/06/ssds#temp_0m http://marinemetadata.org/2005/02/gcmd#Ocean_Temperature http://marinemetadata.org/2005/02/gcmd#Sea_Surface_Temperature http://marinemetadata.org/2005/06/aosn#ocean_temperature

  23. Ontology metadata mediation • Searching “sameAs” and “narrowerThan” for Ocean Temperature • Loading model http://localhost:9600/ont/map-aosn-ssds-gcmd. • Found ssds:Temperature_8 and sea_surface_temperature • Searching ontology http://marinemetadata.org/2005/06/ssds • Found corresponding WSDL for SSDS • http://ssds.shore.mbari.org:8080/axis/services/DataProducer • calling the web service searching Temperature_8 • Number of results added: 4 • Searching ontology http://marinemetadata.org/2005/06/aosn • Found corresponding WSDL • http://mammoth.shore.mbari.org:8080/axis/services/DataProducer • calling the web service searching sea_surface_temperature • Number of results added: 9

  24. Ontology metadata mediation temperature_8 water temperature from unit 00661 Identifier is: urn:ssds.mbari.org.recordVariable.id:243490 water temperature from unit 00829 Identifier 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

  25. Conclusions • 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.

  26. <MMI /> Ontologies MMI Workshop - August 2005

  27. Ontologies Specification of conceptualizations Lake River Example: Properties of real world objects are identified. Similarities are identified. Concepts are created… and are expressed as a class. Classes are related. Is inland body Has a relative defined channel Has water Body of Water Class Subclass Lake River

  28. 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 vocabularies Body of Water River <owl:Class rdf:ID=“Body_of_Water”></owl:Class> <owl:Classrdf:ID=“River”> <rdfs:subClassOf rdf:resource=“# Body_of_Water”/> </owl:Class>

  29. Vocabularies expressed in ontologies Class Looks like a Real world objects Is Transitive Is part of Region Subregion Accounting Unit Cataloging Unit Is part of Is part of Is part of Infer isPartOf Hydrologic Unit Mid Atlantic Delaware Lower Delaware Subclasses Schuylkill Instances

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