Transcript slides
™ 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 ™ Outline Our Experience Desirable Semantic Web Characteristics Support for Common Patterns Other Issues Potential Areas for Standardization 2 ™ Asio Scout Architecture 1 Query Result Set Query: SPARQL Snoggle SWRL Rules 6 Domain Source Ontology OWL Backwards Rule Chaining 5 2 Query Decomposition 3 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 4 RDBMS SOAP WS Data Access KB 3 ™ 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 4 ™ Evolution of Approaches DBMS 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 5 ™ 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? 6 ™ 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 7 ™ 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 8 ™ 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 9 ™ 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) 10 ™ More Information http://asio.bbn.com – SemTech 2007 presentation/demo 11