Suggestions for Semantic Web Interfaces to Relational Databases

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Suggestions forSemantic Web Interfacesto
Relational Databases

• Mike Dean
• mdean_at_bbn.com
• W3C Workshop on RDF Access to Relational
  Databases
• Cambridge, MA
• 26 October 2007

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Outline

• 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 SPARQL
Snoggle
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Query Result Set
Query Decomposition
2
Semantic Query Decomposition (SQD)
Backwards Rule Chaining
5
Generation ofSub Queries
3
Automapper
Semantic Bridge Database
Semantic Bridge Web Service
Semantic Bridge SPARQL Endpoint
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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
Custom Data source ontology
Domain ontology
SWRL Translation rules
DBMS
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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Evolution of Approaches
Optional mapping directives
Generic Data source ontology
Data source ontology
SWRL Translation rules
AutoMapper
Domain ontology
SWRL Translation rules
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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Evolution of Approaches
Optional mapping directives
Generic Data source ontology
Data source ontology
SWRL Translation rules
AutoMapper
Domain ontology
SWRL Translation rules
Busness Rules
DBMS
Generic servlet
translation
Nice SW data
translation
application
inference
application

• Domain ontology is often augmented with
  domain-specific business rules
• A domain ontology may become someone elses 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