From Data Integration To Semantic Mediation: Addressing Heterogeneities in Data
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Transcript of 1 Context Mediation in the Semantic Web Context Mediation in the Semantic Web: Handling OWL Ontology...
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Context Mediation in the Context Mediation in the Semantic WebSemantic Web: Handling OWL Ontology and Data Disparity through Context Interchange
Philip TanSingapore-MIT Alliance (SMA)
Stuart Madnick (Presenter)MIT Sloan School of Management
Kian-Lee TanDepartment of Computer Science, National University of Singapore
SMA Computer Science (CS) – Technical ProgramSMA Computer Science (CS) – Technical Program19-20 January 200519-20 January 2005
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Context Mediation Research and Semantic
Web Research
ContextMediationResearch
SemanticWeb Research
Focus on resolving semanticConflicts amongst Heterogeneous data sources
Focus on making the web semantically richer
Help resolve semanticheterogeneity in OWL/RDF/XML data
Provide a standard (OWL etc) for representingOntology-related knowledge
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Some History COntext INterchange (COIN) system for
semantic interoperability among heterogeneous data sources (started around 1995) Uses COINL, based on FOL/Prolog, to model
semantic knowledge (application ontology and context modifiers)
Web Ontology Language (OWL) becomes W3C Recommendation for ontology publishing (2004)
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Example of Context Mediation situation
. Company_Name
DAIMLER-BENZ AG
TotalAssets
565,9478
Company_Name
DAIMLER BENZ CORP 615,000,000
NetIncome
DAIMLER BENZ
Name
97,736,992
TotalSales
Worldscope
Disclosure
Datastream
Fig. 1. Multiple databases with similar data, but differing contexts Note: NetIncome (profit) exceeds TotalSales – Impressive !
(Issues: currency? Scale factor?)
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“Unit-of-measure mixup tied to loss of $125Million Mars Orbiter”
“NASA’s Mars Climate Orbiter was lost because engineers did not make a simple conversion from English units to metric, an embarrassing lapse that sent the $125 million craft off course. . . .
. . . The navigators ( JPL ) assumed metric units of force per second, or newtons. In fact, the numbers were in pounds of force per second as supplied by Lockheed Martin ( the contractor ).”
Source: Kathy Sawyer, Boston Globe, October 1, 1999, page 1.
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The Context Interchange Approach
ContextMediator
Source Receiver
ReceiverContext
ConversionLibraries
SourceContext
SharedOntologies
ContextTransformation
Context ManagementAdministrator
Concept: Length
Meters Feet f()meters feet
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part length
Select partlengthFrom catalogWhere partno=“12AY”
55.25
F-logic: based on FOL, uses Prolog
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Web Ontology Language (OWL)
W3C Recommendation status publish and share ontologies supporting advanced Web search software agents knowledge management
Three sublanguages Categorization for computational guarantees OWL Lite, OWL DL, OWL Full
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OWL in Action GraduateStudents are Students with a
degree of either BA or BS <owl:Class rdf:ID="Student“/><owl:Class rdf:ID="GraduateStudent"> <rdfs:subClassOf> <owl:Restriction> <owl:onProperty> <owl:ObjectProperty rdf:about="#hasDegree"/> </owl:onProperty> </owl:Restriction> </rdfs:subClassOf> <rdfs:subClassOf rdf:resource="#Student"/> </owl:Class>
Class
Inheritance
Restriction definition
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OWL in Action GraduateStudents are Students with a degree of either BA or BS
<owl:Class rdf:ID="Student“/><owl:Class rdf:ID="GraduateStudent"> <rdfs:subClassOf> <owl:Restriction> <owl:onProperty> <owl:ObjectProperty rdf:about="#hasDegree"/> </owl:onProperty>
<owl:someValuesFrom> <owl:Class> <owl:oneOf rdf:parseType="Collection"> <Degree rdf:ID="BA"/> <Degree rdf:ID="BS"/> </owl:oneOf> </owl:Class> </owl:someValuesFrom> </owl:Restriction> </rdfs:subClassOf> <rdfs:subClassOf rdf:resource="#Student"/> </owl:Class>
Or is it “AB” and “SB”?
Some Harvard degree abbreviations appear to be backwards because they follow the tradition of Latin degree names. The undergraduate degrees awarded by Harvard University are the A.B. and S.B. The A.B. is an abbreviation for the Latin name for the bachelor of arts (B.A.) degree "artium baccalaureus." The S.B., Latin for "scientiae baccalaureus," is the bachelor of science (B.S.).
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Why not be explicit about context ?(i.e., include in data – DB or XML)
Picture of old lady or young lady ?
- Hard to anticipate need (why include currency, if everything is US dollars)
- Hard to get everyone to agree to same context
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Context Interchange in OWL
(COIN-OWL) Extend COIN Two sides of COIN
OWL as COIN’s application ontology representation benefits COIN
COIN as ‘meta-ontology’ for OWL ontology interoperability benefits OWL
Rule Markup (RuleML) Language basis for an integrated rule-markup approach specification for immediate rule interchange Hierarchical language subclasses
Datalog Hornlog
For brevity, COIN-OWL
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Design Approach to Use OWL to Represent COIN Ontology
Preserve constraint programming engine in the eCOIN prototype
Layered architecture:1. Domain ontology modeled in OWL2. OWL ontology transformed to eCOIN Prolog3. Transformed ontology fetched to eCOIN
engine Minimal impact to existing
implementation
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3-Tier Approach
ECOIN Context Mediation
System
ECOIN Context Mediation
System
Ontology Administrator
COIN-OWL
Ontology
ECOIN - Prolog
Program
Ontology Development & Editing
Automated Ontology
Conversion
Context Mediation and Query Processing
(unchanged)
(1)(2)(3)
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Ontology Model Design Domain Model
Semantic types, modifiers, attributes Source Sets
Physical relations and data source Context Axioms
Context, modifier values, conversion functions Elevation Axioms
Semantic relations – mapping source sets to domain model
Context relations – mapping source sets to contexts
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Domain and Context Model in COIN-OWL
<coin:Modifier rdf:ID="mod_scaleFactor"> <coin:ModifierName rdf:datatype="&xsd;string">scaleFactor</coin:ModifierName> <coin:ModifierTo rdf:resource="#basic"/> <coin:ModifierFrom rdf:resource="#companyFinancials"/></coin:Modifier>
<coin:Modifier rdf:ID="mod_currency"> <coin:ModifierName rdf:datatype="&xsd;string">currency</coin:ModifierName> <coin:ModifierTo rdf:resource="#currencyType"/> <coin:ModifierFrom rdf:resource="#companyFinancials"/></coin:Modifier>
<coin:SemanticType rdf:ID="companyFinancials"> <coin:Modifiers rdf:resource=”#mod_scaleFactor”></coin:Modifiers> <coin:Modifiers rdf:resource=”#mod_currency”></coin:Modifiers></coin:SemanticType>
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Challenging area to using Semantic Web:
Modeling Conversion Functions
Previous (RDF/XML) work<coin:Ont_ModifierConversionFunction>convfunc|rule(cvt(companyFinancials, O, currency, Ctxt, Mvs, Vs, Mvt, Vt), (attr(O, fyEnding, FyDate), value(FyDate, Ctxt, DateValue), olsen_p(Fc, Tc, Rate, TxnDate), value(Fc, Ctxt, Mvs), value(Tc, Ctxt, Mvt), value(TxnDate, Ctxt, DateValue), value(Rate, Ctxt, Rv), Vt is Vs * Rv)).rule(month("Oct", 10), (true)). rule(month("Dec", 12), true)).|companyFinancials|currency</coin:Ont_ModifierConversionFunction>
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…Conversion Functions Using RuleML Month name lookup:
rule(month("Jan", 01), (true)). <fact> <_head> <atom> <cterm> <_opc><ctor>rule</ctor></_opc> <cterm> <_opc><ctor>month</ctor></_opc> <ind>Jan</ind> <ind>01</ind> </cterm> <ind>true</ind> </cterm> </atom> </_head> </fact>
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Domain Model
Context Axioms
Elevation Axioms
Source Sets
-Attributes : Attribute-Modifiers : Modifier
SemanticType
-AttributeName-AttributeFrom : SemanticType-AttributeTo : SemanticType
Attribute
-ModifierName-ModifierFrom : SemanticType-ModifierTo : SemanticType-ModifierValues
Modifier
0..1
*
0..1
*
-DataSource-RelationName-Type-Bindings-Operators-Columns
Relation
-ColumnName-DataType-ColumnIndex-AssociatedRelation
Column
1 1..*
-ContextName
Context
-ModifierContext : Context-ModifierObject : Modifier-ModifierSemanticType : SemanticType
ModifierValue
-ModifierStringValue-ModifierNumericValue
ModifierStaticValue
-ModifierDynamicValues : Attribute
ModifierDynamicValue
-ElevationContext : Context-SourceRelation : Relation-SemanticColumns : SemanticColumn
SemanticRelation
-SourceColumn : Column-TargetSemanticType : SemanticType-AssociatedSemanticRelation : SemanticRelation
SemanticColumn
-JoinSourceSemanticColumn : SemanticColumn-JoinValueContext : Context
JoinValue
-JoinTargetSemanticColumn : SemanticColumn
JoinValueColumn-JoinTargetString
JoinValueLiteral
-SourceSemanticColumn : SemanticColumn-TargetSemanticColumn : SemanticColumn-SourceAttribute : Attribute
SemanticAttribute
-JoinValues : JoinValue
ComplexSemanticAttribute
1 *
1
*
Master Plan of COIN Representation in OWL
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COIN-OWL Development Platform
OWL Editor Protégé –extensible architecture, de facto pOWL – web-based development environment
Why Protégé? Easy to use Actively supported Plugins for visualization, diagram
Plugin for Protégé Input: COIN-OWL ontology in OWL, RuleML Output: eCOIN Prolog application ontology
Developed in Java 1.4, Protégé OWL API, XSLT
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Conclusion OWL ontology model for COIN framework
OWL Lite RuleML
COIN-OWL prototype as reference implementation
Adoption of W3C standard reaches wider spectrum of audience
Opportunity to enhance Semantic Web
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Future Work Investigate RuleML Lite, Semantic Web Rule
Language (SWRL) Tighter cohesiveness Reference to OWL ontology via rdf:resource
Address OWL ontology interoperability Problem similar to heterogeneous data
integration Use COIN for context mediation among
ontologies On-going extensions to COIN research
Addressing temporal and aggregational context
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The 1805 Overture
In 1805, the Austrian and Russian Emperors agreed to join forces against Napoleon. The Russians said their forces would be in the field in Bavaria by Oct. 20.
The Austrian staff planned based on that date in the Gregorian calendar. Russia, however, used the ancient Julian calendar, which lagged 10 days behind.
The difference allowed Napoleon to surround Austrian General Mack's army at Ulm on Oct. 21, well before the Russian forces arrived.Source: David Chandler, The Campaigns of Napoleon, New York: MacMillan 1966, pg. 390.