See also: IRC log
<trackbot> Date: 25 January 2011
<boris> I can try to do it
<mhausenblas> scribenick: boris
<souri> who is on the phone?
<souri> aacc is me
<MacTed> :-)
<privera> great thanks
<mhausenblas> PROPOSAL: Accept the minutes of last meeting, see http://www.w3.org/2011/01/18-rdb2rdf-minutes.html
PROPOSAL: Accept the minutes of last meeting
<juansequeda> +1
<betehess> +1
http://www.w3.org/2011/01/18-rdb2rdf-minutes.html
RESOLUTION accepted
RESOLUTION: last telcon minutes accepted by the working group
<MacTed> thanks, ivan
<mhausenblas> scribenick: mhausenblas
http://www.w3.org/2001/sw/rdb2rdf/wiki/TestCases
ACTION-91?
<trackbot> ACTION-91 -- Michael Hausenblas to move accepted TC from wiki to http://www.w3.org/2001/sw/rdb2rdf/test-cases/ -- due 2011-01-25 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/91
<boris> http://www.w3.org/2001/sw/rdb2rdf/test-cases/
<cygri> just joined. sorry i'm late
ACTION-81?
<trackbot> ACTION-81 -- Juan Sequeda to and Eric to draft Direct Mapping TC -- due 2011-01-25 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/81
<boris> http://www.w3.org/2001/sw/rdb2rdf/wiki/TestCases
Boris: now under review,
now
... asked Juan, Eric and Marcelo to contribute
... any questions?
<scribe> scribenick: boris
http://www.w3.org/2001/sw/rdb2rdf/r2rml/
souri: check two actions
regarding this
... one comment from Ivan
issue number ?
michael: go to the actions ...
souri: issue 16
... ISSUE-16?
<souri> ISSUE-16?
<trackbot> ISSUE-16 -- Should we allow multiple subjects for a logical table row? Also, what if no subject is specified? -- raised
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/issues/16
souri: issue with the subjectmap,
cardinality
... we should allow multiple subjectmaps
... one row can have multiple subjects, we allow it
... it is multiple cardinality
... comment from Ivan
... the group has to decide if this make sense
... another action?, what happen if there is no subject
map?
... action related to connect r2rml direct mapping
... what do we do in this particular case?
... we have to use direct mapping? how to specify the direct
mapping?
... we have some ideas to discuss here to the group
... opinion to allow multiple subjectmaps ..
cygri: it will pretty clear
... no harm
... on the other hand is not useful
... no use cases to do that
... it is trade off being flexible or to find a useful
case
... it is also consider in d2r ... depending on the particular
cases
... for example in equivalent classes ...
<mhausenblas> Michael: KISS principle applies - let's mark it for R2RML v2.0
cygri: no harm, but no benefit
michael: ... if we don't have a clear use case ... let's mark it for version 2
noise
souri: e.g. owl:sameAs ...
multiple subjects .... "not materialized" ...
... this is one utility, but he is ok with that
ivan: what is the process should
do?
... if it is only one, I can live with that, but we have to say
something if there are two
souri: I like the error idea
michael, is it a erro?
<ericP> ┌────────┬────────┬──────────┬────────────┬────────────────────┐
<ericP> │ ?FNAME │ ?LNAME │ ?CONTACT │ ?PHYSICIAN │ ?PHYSICIAN_CONTACT │
<ericP> │ Bob │ Smith │ 18 │ Dr. Suess │ 23 │
<ericP> └────────┴────────┴──────────┴────────────┴────────────────────┘
michael: an action for this, what will happen in that case?
<ericP> _:_1 a foaf:Person ; foaf:givenName "Bob" ; foaf:familyName "Smith" ; :doc :_2 .
<ericP> _:_2 a :Physician ; :contact Addres:_23 .
ericP: I show the scenario for this
cygri: one thing: the sameAs
scenario ... not sure if I recommend this .. but it is good
point
... second: agree with Ivan to address cases like this
... error? or what happens?
... so get back to the specification and check how to it
... create an action?
michael: create wiki page, issue, action? ... just not forget it
cygri: volunteer to create a wiki page for this
<mhausenblas> ACTION: Richard to capture this (multiple subject maps) and other (future) potential error cases in the Wiki (ISSUE-16) [recorded in http://www.w3.org/2011/01/25-rdb2rdf-minutes.html#action01]
<trackbot> Created ACTION-96 - Capture this (multiple subject maps) and other (future) potential error cases in the Wiki (ISSUE-16) [on Richard Cyganiak - due 2011-02-01].
<mhausenblas> ACTION-88?
<trackbot> ACTION-88 -- Souripriya Das to adds issues to http://www.w3.org/2001/sw/rdb2rdf/track/issues/ , one for Ashok's concern and one re each of the open, inline-Issues in http://www.w3.org/2001/sw/rdb2rdf/r2rml/ -- due 2011-01-25 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/88
michael: with this action 88 can be closed?
<Seema> Yes
souri: I added the issue ...
<Seema> i.e. action-88 can be closed
seema: yes, it can be closed
<mhausenblas> close ACTION-88
<trackbot> ACTION-88 Adds issues to http://www.w3.org/2001/sw/rdb2rdf/track/issues/ , one for Ashok's concern and one re each of the open, inline-Issues in http://www.w3.org/2001/sw/rdb2rdf/r2rml/ closed
michael: more actions?
<mhausenblas> ACTION-83?
<trackbot> ACTION-83 -- Ashok Malhotra to review R2RML ED -- due 2011-01-25 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/83
michael: ACTION-83
ashok: I'm late
michael: ACTION-92
<mhausenblas> ACTION-92?
<trackbot> ACTION-92 -- Richard Cyganiak to address the R2RML - DM connection -- due 2011-01-25 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/92
cygri: not yet
ACTION-93
<mhausenblas> ACTION-93?
<trackbot> ACTION-93 -- Souripriya Das to identify not-mapping vs. default-mapping issues in R2RML/DM (Wiki or via mail) -- due 2011-01-25 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/93
souri: we discussed with Seema
<ericP> ivan, is the paste i uttered above near what you were thinking about re: multiple subjects?
souri: the idea is to be a gradual specification of the ...
<ericP> i was trying to tease out whether you want repeated properties, or generally just want to partition the properties amounst the created subjects
souri: if we look at the r2rml what are the things we can skip? ... for example subjectmap ...
<ivan> eric, not exactly. At least my idea was that several subjects gets exactly the same predicates
souri: what implies, not to
specify the things in subjectmap and rely on direct map
... do what the direct map can do to get the subjectmap
... other: .... our columns to be predicateobjectmaps
... use direct map to specify the subject and predicate
... only a subset of the columns to the direct map
... exclusion list
<betehess> mhausenblas++
michael: hard to follow
<souri> rr:subjectMap rr:directMapping
souri: the idea is something like
rr:subjectMap rr:directMapping
... similar to the predicateobjectmap
<souri> rr:predicateObjectMaps rr:directMapping
souri: rr:predicateObjectMaps
rr:directMapping
... we can refine this and create an inclusion list
... or except, exclusion
... also can be applied to the refPredicateObjectMap
... better to write an email or in the wiki
michael: what is the overall
approach
... and then we can accept
souri: three points of this subjectmap, predicatemap, refpredicatemap
cygri: ... one table for direct,
two tables for custom
... we have to find out something easy to understand on all
these levels
ivan: what would be really the use case for something like that?
<souri> hooking points for direct-mapping and then refine using inclusions list and exclusions list and '*'
ivan: it's relative complicated ?
souri: use case, let's say we have 10 columns in a table, I only want to customize two columns and for the rest direct mapping
ivan: I understand, but in real
life if I use direct mapping the predicates generated are
really not very nice, and they can be transformed by
sparql
... but if I use r2rml it will be the final rdf
<ericP> i expect this will come up most frequently when folks are doing incremental updates to their r2rml mapping
<ericP> (ivan)
ivan: in practice I would not use that, but maybe I'm wrong
<soeren> +q
michael: we need to specify what do we should do?
cygri: in real life, we have
database 64 tables and convert them to RDF, big job,
... pick one place to start, start with important tables and do
it in a incremental way
<soeren> yes
cygri: one way to support this is direct mapping, and get the default rdf, and the "modify" it
<souri> example: all tables owned by this user modulo an exclusion list
cygri: the other approach would
be: all the tables with direct mapping except employee table,
in this table all the columns mapped except some cols
... it works huge database, at least in d2r
... if I have an empty r2rml, I get the direct mapping and the
data from that mapping
soeren: it's important to have
the incremental approach r2rml
... one option is to have shortcuts
... specify what columns to what properties and the direct
mapping is used for that mappings
<cygri> lol
soeren: let's try to look to see how to simplify ... avoiding to create a lot of stuff
<cygri> well done ericP
<MacTed> /kick ericP
soeren: in this way the mapping language will be more appealing
ivan: michael?
<souri> Specified at three levels: (all tables in) DB, (all tables owned by a) user, (all columns in a) table + refined with INCLUSIONS/EXCLUSIONS/*
michael: sorry
<Zakim> ericP, you wanted to suggest that it delays inventing schema, which can move things along
ericP: motivating use case, 64 tables and we want to express by using foaf or/and dc
<cygri> +1 to ericP
michael: good motivation
ACTION-94
ACTION-94?
<trackbot> ACTION-94 -- Sören Auer to create Wiki page with options for disambiguation interface for well-known entities identifier -- due 2011-01-25 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/94
<mhausenblas> http://www.w3.org/2001/sw/rdb2rdf/wiki/Entity_disambiguation
soeren: I created the wiki page
<mhausenblas> close ACTION-94
<trackbot> ACTION-94 Create Wiki page with options for disambiguation interface for well-known entities identifier closed
soeren: and it is linked from the linked data aspects
<mhausenblas> yes, ivan, should be open
soeren: wrote 3 approaches to solve this
first one: entity resprestation on the database columns
<mhausenblas> Michael: I ask the R2RML editors to change status of ISSUE-16 to open
scribe: second mapping funcitons
third: using entity mapping
table
... the easiest way is the r2rml core editors ... database
column variants ..
... create uris based on namespaces prefixes predifned
souri: r2rml allows to do that
michael: thanks soeren
... how to proceed now?
soeren: we should discuss which
of the variants we need?
... the first one works good
... it depends on the scenarios
cygri: third approach probably
won't work with r2rml
... the main point is to store the alignment on the database,
and this should work
... in scenarios where we cannot modify the database
... second approach: the main problem where is the
implementation of the functions are coming from
... from the spec or free implementation
... java class that implement the function, or stored procedure
or web service
michael: we don't want to go in
much detail regarding the implementation
... for example an xslt
cygri: in d2rq we can specify a java class
soeren: the processor has to understand whether is a java class, web service ... etc
cygri: you can say, expected
input, output and uri
... that would be possible
michael: we have to gather a bit
of experience on implementation
... for example dbpedia lookup, and the possible problems we
can have
soeren: second option: one
problem function one to one
... second problem: could be cases we can have two syntaxes
variations of a uri
ericP: rdf says two different uris two different resources
michael: usually you have to define a normalization process
ericP: I would not expect that ... on normalization
soeren: extract a part of the URI ... in this case mapping functions won't work any more
michael: don't think to worry about it, I'm with ericP
<ericP> FILTER ( tolower(scheme1) = tolower(scheme2) )
cygri: volunteer for the second
one ...draft a simple interface .. and gather implementations
experiences
... to include cases from d2rq
... on the wiki page
<mhausenblas> ACTION: Richard to look into D2RQ implementation and update http://www.w3.org/2001/sw/rdb2rdf/wiki/Entity_disambiguation [recorded in http://www.w3.org/2011/01/25-rdb2rdf-minutes.html#action02]
<trackbot> Created ACTION-97 - Look into D2RQ implementation and update http://www.w3.org/2001/sw/rdb2rdf/wiki/Entity_disambiguation [on Richard Cyganiak - due 2011-02-01].
<ericP> soeren, i understand the motivation, and sympathise with the desire for a smarter notion of equivalence, but i think it's unlikely ('cause it's expensive) so i wanted to demoralize you as soon as possible
cygri: the third approach should be included as well
souri: David sent some mails about sql query specification
<mhausenblas> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2011Jan/0069.html
souri: constructing portions of the logical table. .. it would be a good idea
<mhausenblas> ACTION-85?
<trackbot> ACTION-85 -- Ted Thibodeau to review Direct Mapping ED -- due 2011-01-25 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/85
<mhausenblas> ACTION-95?
<trackbot> ACTION-95 -- Juan Sequeda to create issues for DM draft -- due 2011-01-26 -- CLOSED
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/95
michael: a lot of issues
... so next time to check all the issues there
<mhausenblas> http://www.w3.org/2001/sw/rdb2rdf/track/issues/raised
michael: for the next week a lot of direct mapping issues
<mhausenblas> close ACTION-95
<trackbot> ACTION-95 Create issues for DM draft closed
ashok: to ten minutes on the
issues
... and classify them into simple, not simple, etc.
betehess: add new rules
marcelo: we will do it for next week
<MacTed> these including all Juan's issues? http://www.w3.org/2001/sw/rdb2rdf/track/issues/raised
juan: face to face with marcelo
michael: let's do what ashok suggested
ISSUE-9?
<trackbot> ISSUE-9 -- Generate Blank Nodes for duplicate tuples -- raised
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/issues/9
michael: any comments?
ashok: I haven't look at this
juan: let's do it over email
michael: have a look on all of these issues
<betehess> can I add issues?
michael: and next time we will check then
<betehess> you'll hate me
thanks
<mhausenblas> [meeting adjourned]
thanks, I forgot it ...
Ok, I'll send them
<mhausenblas> trackbot, end telecon
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