<<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