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Suggestions for
Semantic Web Interfaces
to Relational Databases
Mike Dean
[email protected]
W3C Workshop on RDF Access to Relational Databases
Cambridge, MA
26 October 2007
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Outline
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Our Experience
Desirable Semantic Web Characteristics
Support for Common Patterns
Other Issues
Potential Areas for Standardization
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Asio Scout Architecture
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Query Result Set
Query: SPARQL
Snoggle
SWRL Rules
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Domain Source
Ontology
OWL
Backwards
Rule Chaining
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Query
Decomposition
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Generation of
Sub Queries
Semantic Query Decomposition (SQD)
WSDL
Mapping
Ontology
Automapper
Data Source
Ontology
WSDL
Ontology
Data Source
Ontology
OWL
OWL
Semantic Bridge
Database
OWL
OWL
Semantic Bridge
Web Service
Semantic Bridge
SPARQL Endpoint
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RDBMS
SOAP
WS
Data Access
KB
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Semantic Web Characteristics
 Publishing each data model as an OWL
ontology
 Use of resolvable URIs
 Favoring the use of object properties over
datatype properties
 Use of datatypes
 Use of accepted conventions such as
camelCaseNames and singular class names
 Reuse of or mappings to existing vocabularies
such as FOAF and Dublin Core
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Evolution of Approaches
DBMS
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Custom
Data source
ontology
SWRL
Translation
rules
Domain
ontology
Custom
servlet
translation
application
Expose each data source with an OWL representation of its native data
model
Use SWRL to represent structural transformations, unit conversions, etc.
Support cross-product of producers and consumers
Gold standard in terms of output quality
Labor-intensive
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Optional
mapping
directives
Evolution of Approaches
AutoMapper
Generic
Data source
ontology
SWRL
Translation
rules
Data source
ontology
SWRL
Translation
rules
Domain
ontology
DBMS
Generic
servlet
translation
“Nice”
SW data
translation
application
 Get the data into Semantic Web format quickly
and then apply Semantic Web tools
 Much less labor to achieve similar results
 How “nice” can we make the first stage output?
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Optional
mapping
directives
Evolution of Approaches
AutoMapper
Generic
Data source
ontology
SWRL
Translation
rules
Data source
ontology
SWRL
Translation
rules
Domain
ontology
“Busness
Rules”
DBMS
Generic
servlet
translation
“Nice”
SW data
translation
application
inference
application
 Domain ontology is often augmented with domainspecific business rules
 A domain ontology may become someone else’s data
source
 N-level approach
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Support for Common Patterns
 Most databases are now designed from
an ER or OO model – this higher-level
model should be exposed
 Parent and child tables for inheritance
 Implicit class hierarchies (“type” column)
 N-ary relations
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Other Issues
 Use of resolvable URIs
– Support HTTP GET as well as SPARQL
– Ensure that returned URIs can be used in
subsequent SPARQL queries
– “External foreign keys” – links to open data
 Security
– Non-public data sources require authentication
 Performance
 Update
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Potential Areas for Standardization
 Table and column to class and property
mappings
 SQL datatype to XML Schema datatype
mappings
 SPARQL to SQL translation
 Web service interfaces (including
authentication)
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More Information
 http://asio.bbn.com
– SemTech 2007 presentation/demo
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