W3C

RDB2RDF Working Group Teleconference

02 Aug 2011

Agenda

See also: IRC log

Attendees

Present
mhausenblas, +1.617.324.aaaa, ericP, Ivan, juansequeda, cygri, +49.153.6.aabb, boris, MacTed, soeren, nunolopes, Souri, Seema, +1.314.394.aacc, dmcneil, Michael, Eric, Juan, Boris, Soeren, Ted, Nuno, David
Regrets
Marcelo, Ashok
Chair
Michael
Scribe
mhausenblas

Contents


<trackbot> Date: 02 August 2011

<scribe> scribenick: mhausenblas

<boris> hi

Admin

PROPOSAL: Accept the minutes of last meeting http://www.w3.org/2011/07/26-rdb2rdf-minutes.html

RESOLUTION: Accept the minutes of last meeting http://www.w3.org/2011/07/26-rdb2rdf-minutes.html

SQL/XSD data dataype mapping

ACTION-141?

<trackbot> ACTION-141 -- Nuno Lopes to create a SQL/XSD data dataype mapping in the Wiki until next week -- due 2011-07-26 -- CLOSED

<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/141

close ACTION-141

<trackbot> ACTION-141 Create a SQL/XSD data dataype mapping in the Wiki until next week closed

-> http://www.w3.org/2001/sw/rdb2rdf/wiki/Mapping_SQL_datatypes_to_XML_Schema_datatypes

Michael: thanks, Nuno, nice job

Nuno: Based on ISO/IEC 9075-14:2008 Part 14 XML-Related Specifications
... with the restrictions/facets
... question is how deep we want to go with this
... for example excluding the user-defined types
... or constructed types
... unsure if we should consider this

Michael: comments?

<cygri> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2011Jul/0163.html

Richard: Really useful, thanks
... above are my questions
... I understand you need some time to address my questions
... there are situations where we want to map to plain strings
... via casting
... toString (SQL-built-in)
... and we can use this as a fallback

Michael: does this always make sense?

Richard: impl. dependent

Michael: we need to keep this up

Richard: any volunteers?

<cygri> ACTION: nuno to look into how SQL 2008 handles CAST of user-defined types and constructed types to string [recorded in http://www.w3.org/2011/08/02-rdb2rdf-minutes.html#action01]

<trackbot> Created ACTION-149 - Look into how SQL 2008 handles CAST of user-defined types and constructed types to string [on Nuno Lopes - due 2011-08-09].

Eric: so, we look into this to figure if we have an RDF mapping?

Richard: we need to figure a way how to deal with it - simplest would be to relay on the SQL 2008 spec

<ericP> "Data conversions between a user-defined

<ericP> type and another data type are defined by a user-defined cast."

<dmcneil> +q

David: wondering where it is heading
... we started out rather simple?

Richard: if there is a well defined translation to XSD (such as xsd:integer) use that

<ericP> i don't think there are any well-defined conversions from e.g. COMPLEX_NUMBER to CHAR(n)

Richard: if there is none, but the implementation knows how to do the toString use that

<ericP> that when you introduce e.g. COMPLEX_NUMBER, htat you ought to introduce the appropriate casts

ISSUE-29 - resource identifiers as strings

<cygri> ericP, i think we just need cast to string

ACTION-124?

<trackbot> ACTION-124 -- Seema Sundara to implement decision re ISSUE-29 (bNodes identifier and URI expressions be of string types) -- due 2011-08-02 -- OPEN

<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/124

ACTION-147?

<trackbot> ACTION-147 -- Richard Cyganiak to implement ISSUE-29 resolution by stating that conversion to string is done implicitly in any context where a string value is required, and is done according to the rules for SQL's CAST expression. Columns whose type cannot be CAST to string MUST NOT be used in a context that requires a string; and mark the issue as pending review -- due 2011-08-02 -- OPEN

<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/147

<Seema> yes, it does

close ACTION-124

<trackbot> ACTION-124 Implement decision re ISSUE-29 (bNodes identifier and URI expressions be of string types) closed

<ericP> cygri, that makes sense, and if the UDT which provides a new type doesn't give you a cast, then you were going to lose anywyas

Actions

ACTION-137?

<trackbot> ACTION-137 -- Souripriya Das to create proposal for IRIs to resolve ISSUE-45 -- due 2011-07-05 -- PENDINGREVIEW

<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/137

close ACTION-137

<trackbot> ACTION-137 Create proposal for IRIs to resolve ISSUE-45 closed

close ISSUE-45

<trackbot> ISSUE-45 IRIs instead of literals for rr:termType choices closed

ACTION-139?

<trackbot> ACTION-139 -- Boris Villazón-Terrazas to move the R2RML extended examples from the specification to the Test Cases document - ISSUE 52 -- due 2011-08-09 -- OPEN

<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/139

close ACTION-139

<trackbot> ACTION-139 Move the R2RML extended examples from the specification to the Test Cases document - ISSUE 52 closed

ACTION-140?

<trackbot> ACTION-140 -- Boris Villazón-Terrazas to produce an RDF Schema representation of the R2RML vocabulary terms. -- due 2011-08-09 -- OPEN

<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/140

<cygri> see http://www.w3.org/ns/r2rml#

Richard: we have updated the R2RML namespace document, see above
... we have synced it

Michael: Thanks to Ivan for the support

Ivan: is it planned to make it data-in-HTML aware?

Richard: At the moment it is not clear who is responsible for the namespace document

Michael: is there an issue for this?

<cygri> this is ISSUE-53

ISSUE-53?

<trackbot> ISSUE-53 -- RDFS vocabulary reference for R2RML, and namespace document -- open

<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/issues/53

Michael: how about resolving it now with Boris as maintainer

Ivan: let's use http://www.w3.org/2001/sw/rdb2rdf/track/products

<cygri> ivan++

PROPOSAL: the WG considers LC-relevant issues only in the R2RML and DM product group of the tracker http://www.w3.org/2001/sw/rdb2rdf/track/products

<cygri> +1

<boris> +1

<juansequeda> +1

<ivan> +1

<Souri> +1

RESOLUTION: the WG considers LC-relevant issues only in the R2RML and DM product group of the tracker http://www.w3.org/2001/sw/rdb2rdf/track/products

Issues without actions or unclear who is on it

ISSUE-54?

<trackbot> ISSUE-54 -- Simpler constant-valued term maps -- open

<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/issues/54

Michael: who is on this?

Richard: a proposal for syntactic sugar

Michael: is it doable in the time we have w/o distracting from the MUST-issues?

Richard: don't know in detail

<dmcneil> personally I lean towards "postpone" on this, because I feel like we need to push to get the last-call spec out

Richard: in terms of impl not a big deal but might induce discussion

Michael: let's leave it open for now

Richard: seems the same for ISSUE-57 - ISSUE-60

ISSUE-61?

<trackbot> ISSUE-61 -- Re-using public entity identifiers - look-up table -- open

<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/issues/61

<scribe> ACTION: Richard to come up with a proposal for ISSUE-61 (entity ID look-up table) [recorded in http://www.w3.org/2011/08/02-rdb2rdf-minutes.html#action02]

<trackbot> Created ACTION-150 - Come up with a proposal for ISSUE-61 (entity ID look-up table) [on Richard Cyganiak - due 2011-08-09].

Richard: IIRC there was a comment from Souri that if we do this then it should be bijective
... I'd be interested in why?

Souri: If it is not 1:1 then, it is feels a little bit odd

Richard: In D2RQ we have bijective mappings, error otherwise
... from implementation POV it's easy
... but in use it's inflexible
... can't report on experience with the more flexible mapping, though
... unsure what the right way is

Souri: it's obviously much cleaner if it is a 1:1 mapping
... the value of non-bijective mappings is there, and should be possible to do

Seema: we can handle 1:M

Souri: what are the two sides of the mapping?

Richard: DB column and RDF term
... type code for example 1... abc:accepted, 2 ... abc:rejected

Michael: what's the insight now?

Richard: I'll propose a M:N mapping then
... maybe I'll use SKOS?

<dmcneil> it doesn't seem to me that we can reach into unknown territory at this point, since we are trying to wrap things up for last call

<dmcneil> i am not referrring to SKOS, but to trying to do M:N lookups

David: M:N is too far reaching

<ivan> +1 to dmcneil

<Souri> many-to-many mapping => :AsianCuisine => "Chinese", "Japanese", "Vietnamese", "Indian" ; :SpicyCuisine => "Indian" ; I am not sure about implementation complexity (not for constants, but translating the DB result back to RDF terms)

Michael: Let's try to see how far we get with the M:N mapping, fallback is 1:1

Richard: I understand the concern and I agree that none of the above issues should keep us from going LC
... I invested quite some time to have the buffer now for 'optimizations' ;)

RDB2RDF Test Cases status (Boris)

-> http://www.w3.org/2001/sw/rdb2rdf/test-cases/ Test Cases document

<boris> https://dvcs.w3.org/hg/rdb2rdf-tests

<dmcneil> from my perspective it seems to me that we barely have enough time to get to last call with the features that we have (there is no need to discuss it further, just wanted to get my view out there)

<boris> https://dvcs.w3.org/hg/rdb2rdf-tests/file/6a177981074b/D000-1table0rows/manifest.ttl

<boris> http://www.w3.org/2001/sw/rdb2rdf/test-cases/TCOverview.html

Michael: thanks a lot, David, for your input - I appreciate it and very much value it!
... Thanks Boris for the hard work

AOB

Michael: next week we focus on DM

[adjourned]

trackbot, end telecon

Summary of Action Items

[NEW] ACTION: nuno to look into how SQL 2008 handles CAST of user-defined types and constructed types to string [recorded in http://www.w3.org/2011/08/02-rdb2rdf-minutes.html#action01]
[NEW] ACTION: Richard to come up with a proposal for ISSUE-61 (entity ID look-up table) [recorded in http://www.w3.org/2011/08/02-rdb2rdf-minutes.html#action02]
 
[End of minutes]

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$Date: 2011/08/02 17:06:01 $