See also: IRC log
<ericP> apologies, i sent my regrets to public-rdb2rdf-wg@gmail.com !
<ericP> i have no idea how my mua elected to default to that domain
Admin Minutes Telephone Telcon on Tuesday? SemTech Panel What is an Ontology? SQL-based approach RDF-based approach Direct mapping Reverse mapping? How to make standard a success
<scribe> AGENDA:
Admin Minutes Telephone Telcon on Tuesday?
SemTech Panel
What is an Ontology?
SQL-based approach
RDF-based approach
Direct mapping
scribe: reverse mapping?
... schema question
How to make standard a success?
<juansequeda> What is the usecase for RDB2RDF?
<juansequeda> What are practical experiences?
<juansequeda> What are potential different approaches?
<juansequeda> Why a standard?
<juansequeda> How long is this going to take?
The above are questiine we discussed on the last telcon
<sdas2> Why should I go for it? What are the benefits? Is if feasible? How much effort will it involve on the user side?
Souri: What is it that you cannot do with SQL that you can do with SPARQL?
... integration on data is important ... RDF has no structure
... inference becomes possible
... can create domain ontology with domain knowledge
Ashok: Even a few rules, a liitle inference makes the data very useful
Richard: I can add a view that makes the inference pssible
Dan: What is the source of the semantics?
Juan: Can be a means to an end ... just dreate the RDF
Richard: Three reasons
... Data integration
... Inferencing
... Making data avaialible on the web'
... I can speak about practical experiences with D2RQ
Juan: Triplify has some experience ... e.g. RDF view on OpenStreet map
Souri: Maybe Orri can mention about HCLS
Ashok: Potentially different approaches ...
... SQL approach, D2RQ, ...
... Virtusose RDF views
Souri: People will want to ask about limitations, performance
Ashok: Why a standard?
... Why do we need a standard?
Souri: Data can be fragmented ...
... people will use different databases
Richard: D2RQ works with diferent databases
... Need support tools
... people will write tools around the standard
... ... standard creates a ecosystem
Ashok: How long will it take --- I think between 18 months and 2 years
Souri: How much effort on user's side?
Ashok: There will be tools to help the user
Souri: They will have to buy tools and set them up etc.
Richard: How does this make integration easier than just integrating the data
Souri: database integration is a very hard problem
... we give you a useful approach which helps
Dan: Database integration helps you set the ground for inference
... need metadata
BREAK for 10 minutes
<juansequeda> Slides: http://juansequeda.com/rdb2rdf/Ontologies.pdf
Richard: No ontology case and putative ontology cases are very similar just that there is more information about the URIs that name the classes and properties
Souri: User needs ontology to help write the query
Richard shows demo that shows bits of the RDF graph and help writes the query
Dan: RDF people are comfortable about not being explicit about the metadata
Juan: We already have a glossary, but we all need to be conceptually on the same page.
... we need to explicit about terms and agree
Richard: Be explicit about design space
Souri: I will send out the foils to the list
... somewhat modified version of out presentation
Dan: Referential constraints capture domain semantics
Richard: Ontology brings in its own constraints
Souri: we need to speficy Class(Classname, SQLdefString)
Richard: Can I have 2 statements with same classname
... yes, then we will need a union
... Could I have no class?
... You have an OWL had on ... I have RDF hat
... in RDF I can have a node without a type
Souri: Thre types of statements in the mapping language: Class, Property, Constraint
... Discusses subtypes
RESUMING after lunch
<scribe> ACTION: to rcygania2 document issues on the SQL-based approach [recorded in http://www.w3.org/2010/06/20-rdb2rdf-minutes.html#action01]
<trackbot> Sorry, couldn't find user - to
ACTION Document issues on the SQL-based approach on rcygania2 due July 10
<trackbot> Sorry, couldn't find user - Document
<scribe> ACTION: rcygania2 to document issues on the SQL-based approach due July 8 [recorded in http://www.w3.org/2010/06/20-rdb2rdf-minutes.html#action02]
<trackbot> Created ACTION-66 - Document issues on the SQL-based approach due July 8 [on Richard Cyganiak - due 2010-06-27].
<scribe> ACTION: sdas2 to write first draft of SQL-based approach due July 22 [recorded in http://www.w3.org/2010/06/20-rdb2rdf-minutes.html#action03]
<trackbot> Created ACTION-67 - Write first draft of SQL-based approach due July 22 [on Souripriya Das - due 2010-06-27].
<scribe> ACTION: jsequeda to write note on Ways to Leverage Ontologies due July 8 [recorded in http://www.w3.org/2010/06/20-rdb2rdf-minutes.html#action04]
<trackbot> Created ACTION-68 - Write note on Ways to Leverage Ontologies due July 8 [on Juan Sequeda - due 2010-06-27].
cygri: I will show examples from code that Eric wrote
... this is from a scalar file that Eric sent around
... uses SPARQL construct quireies from a direct mapping to a domain ontology
... each prefix corersponds to a table
... maps a column to a triple value
Souri: The SPARQL query is written against the direct mapping subgraph
... two steps
... storing this definition and using it to translate the SPARQL query
cygri: Uses SPARQL 1.o so cannot do value translation
... I don't accept that SQL translate is hard to do
Dan: This is for folks who are fluent in SPARQL rathar than SQL
Cygri: 2 downsides, one is the 2 levels of translation. The other is that we need SPARQL 1.1 expressivity
... advantage is that what you get out is very explicit
cygri Perhaps look at an example from SQL-based approach and see how it looks in SQL approach
Souri: Perhaps annotate SQL with what the SPARQL looks like
Ashok: The primary key and foriegn key constructs are not expressed
... can you translate the sql-based example to the rdf-based example automatically
cygri: Should be possible if SQL part is a simple table ... if it is more complex it is not clear
Ashok: To net it out, the RDF-based approach is easier for the RDF/SPARQL expert but ...
1. requires SPARQL 1.1 for expressivity
2. needs two levels of translation
scribe: question about generating the RDF graph from the SQL-based approach
Work with Marcelo
<juansequeda> http://juansequeda.com/rdb2rdf/DirectMapping.pdf
Datalog rules to map from SQL schema to ontology and RDF
some database rules sucg as check constraints cannot be expressed
Cygri: Need much less than this for the default mapping in RDF-based approach
- Base table vs. view
Cygri: What can be customized:
- Class name
- Property name
- URI or literal or blank node
- datatype
- langauge tag
c/langauge/language/
cygri: Kevin Wilkinson from HP Labs (jena 2) has a paper to create relational schema from RDF/OWL
Souri: We have a paper on materialized views
Souri: As a first cut not do object types ... just stick to scalar types
Dan: Let's just stick to types that map to XML Schema types
Cygri: Objects can be serialized ... so we can say we just support serialized objects
... need a list of datatypes we support
Ashok: Allow extension points for vendor-specific datatypes
Cygri: Need to be able to handle unknown datatypes
... Need some simple tools to create mapping statements
ADJOURNED
rrsagent make minutes