<MMI />

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ltMMI /gt
Ontology Semantic Mediation in the Big Picture
MMI Workshop - August 2005
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Semantic Issues
What is the meaning ?
How are the terms related ?
Data
Metadata
http//www.ws-i.org/img/juggler.gif
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Information systems talk different languages
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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
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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
Source type (Platform/Sensor/ instrument/model) Lat Long Depth Time (Z) Latest value (units) Link to Metadata and data
category
label_of_source
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MMI Demo for Demo WSDL Source
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Metadata in DCMI
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MMI Demo for Demo WSDL Source
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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-DDThhmmss) 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-DDThhmmsshhmm or
  YYYY-MM-DDThhmmsshh.
• Missing values write "null" in lowercaps

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So far looks good, so where do we have semantic
mediation problems ?
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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)
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Needed controlled vocabularies
UnitsParametersPhenomenaModelsSensorsInstrume
ntsFormatsOrganizationsGeographic
PlacesDatumsSpecies categories etc
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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
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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.

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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).

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MMI Strategy Faciliate semantic mediation

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

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Guides for Harmonization
HTML
Comma Separated Values
DTD
Tab Separated Values
XML/XSD
OWL
Relational Database
RDF
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Ontologies Repository
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Mapping Tools
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Web services
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Demonstration Ontology metadata mediation
1) Vocabulary Harmonization
2) Vocabulary Mapping
3) Vocabulary Services
4) Access to Data
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Demo Ontology metadata mediation
http//marinemetadata.org/2005/06/ssdsTemperature
_8 http//marinemetadata.org/2005/06/ssdsTemperat
ure_3 http//marinemetadata.org/2005/06/ssdsTempe
rature_1 http//marinemetadata.org/2005/06/ssdsTe
mperature_5 http//marinemetadata.org/2005/06/ssds
Temperature_7 http//marinemetadata.org/2005/06/s
sdsisusTemp http//marinemetadata.org/2005/06/aos
nsea_surface_temperature http//marinemetadata.or
g/2005/06/ssdsTemperature_2 http//marinemetadata
.org/2005/06/ssdsTemperature_9 http//marinemetad
ata.org/2005/06/ssdsTemperature_6 http//marineme
tadata.org/2005/06/ssdsTemperature_4 http//marin
emetadata.org/2005/06/ssdstemp_0 http//marinemet
adata.org/2005/06/ssdstemp_0m http//marinemetada
ta.org/2005/02/gcmdOcean_Temperature http//marin
emetadata.org/2005/02/gcmdSea_Surface_Temperature
http//marinemetadata.org/2005/06/aosnocean_temp
erature
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Ontology metadata mediation

• Searching sameAs and narrowerThan for Ocean
  Temperature
• Loading model http//localhost9600/ont/map-aosn-s
  sds-gcmd.
• Found ssdsTemperature_8 and sea_surface_temperatu
  re
• Searching ontology http//marinemetadata.org/2005/
  06/ssds
• Found corresponding WSDL for SSDS
• http//ssds.shore.mbari.org8080/axis/services/Dat
  aProducer
• 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.org8080/axis/services/
  DataProducer
• calling the web service searching
  sea_surface_temperature
• Number of results added 9

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Ontology metadata mediation
temperature_8 water temperature from unit
00661 Identifier is urnssds.mbari.org.recordVari
able.id243490 water temperature from unit
00829 Identifier is urnssds.mbari.org.recordVari
able.id141923 Sea Surface Temperature Observa
tion Data/Drifters/MBARI Drifter 4
(8/11-9/5/2003)/Sea Surface Temperature
(count190) Identifier is urnaosn.mbari.org.reco
rdVariable.i.id243483 Observation
Data/Aircraft/Sea Surface Remote Sensing and
Atmospheric Meteorology (8/4-6,10-11,13,15,20-22,2
5,29,9/4-5,6/2003)/Sea Surface Temperature
(count148538) Identifier is urnaosn.mbari.org.r
ecordVariable.id44
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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.

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ltMMI /gt
Ontologies
MMI Workshop - August 2005
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Ontologies Specification of conceptualizations

• 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
River
Lake
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Web Ontology Language OWL

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

Body of Water
River
ltowlClass rdfIDBody_of_Watergtlt/owlClassgt lto
wlClass rdfIDRivergt ltrdfssubClassOf
rdfresource Body_of_Water/gt lt/owlClassgt
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Vocabularies expressed in ontologies
Hydrologic Unit
Mid Atlantic
Delaware
Lower Delaware
Subclasses
Schuylkill
Instances