See also: IRC log
<trackbot> Date: 08 February 2011
<juansequeda> mhausenblas, I might not be able to call in. So I'll be just *listening* through irc
<mhausenblas> scribenick: ericP
<mhausenblas> PROPOSAL: Accept the minutes of last meeting, see http://www.w3.org/2011/02/01-rdb2rdf-minutes.html
<boris> +1
+1
<Souri> aadd is me
RESOLUTION: http://www.w3.org/2011/02/01-rdb2rdf-minutes.html is a record of the last meeting
mhausenblas: SemTech session not accepted
<mhausenblas> http://www.w3.org/2011/03/w3c-track.html
mhausenblas: can we exploit the W3C track at WWW2011?
ivan: W3C has to pick two major
topics for the track. those have already been announced
... you can ask mcf, but at WWW2010, both days were consumed by
the two announced topics
... i plan to be at WWW2011, happy to jump in
<mhausenblas> ACTION: mhausenb to ask Marie-Claire Forgue if there is a chance to present or discuss RDB2RDF at the W3C track at WWW2011 [recorded in http://www.w3.org/2011/02/08-rdb2rdf-minutes.html#action01]
<trackbot> Created ACTION-100 - Ask Marie-Claire Forgue if there is a chance to present or discuss RDB2RDF at the W3C track at WWW2011 [on Michael Hausenblas - due 2011-02-15].
ivan: perhaps a workshop has a slot for an e.g. panel
mhausenblas: would be happy to have an RDB2RDF sandwich board
<scribe> ACTION: ivan, mhausenblas to investigate alternatives at SemTech [recorded in http://www.w3.org/2011/02/08-rdb2rdf-minutes.html#action02]
<trackbot> Sorry, couldn't find user - ivan,
<scribe> ACTION: ivan to investigate alternatives at SemTech [recorded in http://www.w3.org/2011/02/08-rdb2rdf-minutes.html#action03]
<trackbot> Sorry, amibiguous username (more than one match) - ivan
<trackbot> Try using a different identifier, such as family name or username (eg. ivan, imikhail)
<scribe> ACTION: herman to investigate alternatives at SemTech [recorded in http://www.w3.org/2011/02/08-rdb2rdf-minutes.html#action04]
<trackbot> Created ACTION-101 - Investigate alternatives at SemTech [on Ivan Herman - due 2011-02-15].
<mhausenblas> ACTION-92?
<trackbot> ACTION-92 -- Richard Cyganiak to address the R2RML - DM connection -- due 2011-02-08 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/92
<mhausenblas> ACTION-93?
<trackbot> ACTION-93 -- Souripriya Das to identify not-mapping vs. default-mapping issues in R2RML/DM (Wiki or via mail) -- due 2011-02-08 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/93
Souri: some progress
<Souri> http://www.w3.org/2001/sw/rdb2rdf/wiki/Use_of_Direct_Mapping_in_R2RML
-> http://www.w3.org/2001/sw/rdb2rdf/wiki/Use_of_Direct_Mapping_in_R2RML Use of Direct Mapping in R2RML
Souri: say we have triples map
with a subject map and one or more predicate object maps
... it becomes tedious to list PO maps for each column
<mhausenblas> scribenick: mhausenblas
Michael: fine, let's give Souri a bit more time to flesh out details
Ivan: I think Michael and Souri are talking about the same thing (continuum from DM to full R2RML)
<ericP> soeren: would like to see a directive to enable default mapping
<scribe> scribenick: ericP
soeren: would like to see a directive to enable default mapping
Souri: looking at bullet one, PO
maps include direct mapping
... second bullet includes r2rml:exclude
... third bullet has r2rml:includes -- start empty and include
explicitly include columns
<mhausenblas> ACTION-96?
<trackbot> ACTION-96 -- Richard Cyganiak to capture this (multiple subject maps) and other (future) potential error cases in the Wiki (ISSUE-16) -- due 2011-02-08 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/96
mhausenblas: action remains open
<mhausenblas> ACTION-97?
<trackbot> ACTION-97 -- Richard Cyganiak to look into D2RQ implementation and update http://www.w3.org/2001/sw/rdb2rdf/wiki/Entity_disambiguation -- due 2011-02-08 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/97
Souri: in the last meeting, we discussed blank nodes in the direct mapping
<mhausenblas> ISSUE-9?
<trackbot> ISSUE-9 -- Generate Blank Nodes for duplicate tuples -- open
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/issues/9
Souri: stimulated email discussion
<boris_> why we don't collect all the possibilities on a wiki page? (regarding blank nodes)
<soeren> http://www.w3.org/2001/sw/rdb2rdf/track/issues/9
soeren: i have the impression
that we are divided on bnodes
... some don't want them for linked data reasons
ivan: i feel we should remain as
we have it
... direct mapping philosophy assumes another layer of
massage
... if i want to push data into an LD environment, the second
stage can take care of it
... if we eliminate bnodes, it will be complicated to generate
URIs for what are currently bnodes
... 'cause we need to communicate to folks (via e.g. url
scheme) that this node is effectively a bnode
<boris_> yes
mhausenblas, has this anything to do with r2rml?
MacTed: guidance around bnodes is that we want to avoid them 'cause they cause trouble down the line
<Zakim> ericP, you wanted to ask how non-repeatable "persistent" identifiers can be used
<mhausenblas> scribenick: mhausenblas
ericP: in the relational model we
have IDs for tupels
... using PK to identify a tuple
... if we have some data via DM and we advertise some IDs other
than the PK, it might no longer be valid
... so we have a unreliable URI if tuple changes
<ivan> +1 to Eric
ericP: so bNodes are the only
reliable mechanism for tuples that might change
... so, I'm all for preserving the current status
<ericP> mhausenblas: our charter says we have to be linked-data-friendly
<scribe> scribenick: ericP
MacTed: there is a temporality to
RDB-contained data
... the graphs captured should reflect that temporarility
<Zakim> mhausenblas, you wanted to remind on our charter
ericP: but these syntehtic identifiers can't be used
MacTed: you can have a document which describes this identifer, giving a time windows
ivan: blank nodes issue came up at RDFNext
<mhausenblas> ACTION: Ted to sum up the possibilities for generating reliable URIs for DM (to avoid bNodes) on the Wiki [recorded in http://www.w3.org/2011/02/08-rdb2rdf-minutes.html#action05]
<trackbot> Created ACTION-102 - Sum up the possibilities for generating reliable URIs for DM (to avoid bNodes) on the Wiki [on Ted Thibodeau - due 2011-02-15].
<ivan> http://bnode.w3.org/UUID-based-ID
ivan: david booth proposed a URI
scheme for anonymous nodes
... if a client sees that URI, they can dereference it but get
something which which isn't very informative
<MacTed> that is a potentially viable suggestion...
ivan: if we want to do this, we have to precisely define this URI scheme
<MacTed> much like the canonical variable names -- foo, bar, blat, thud...
Souri: some RDBs have a
persistent identifier, e.g. Oracle's rowid
... but what if the table gets moved? we can't use it as an
identifer anymore
... but we need to communicate that it may suddenly
disappear
<Souri> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2011Feb/0035.html
Souri: i.e. that it's not so
reliable
... i tried to compare the bnode and the synthetic URI
cases
... if we're returning this URI based on a uniqe sequence
number from a query, or returning a bnode, neither can be used
again
<MacTed> that also covers the temporal nature
<Zakim> ericP, you wanted to ask what is the motivation to assign URIs which we can't re-use?
<ivan> I think that Souri's description is indeed close to David's approach
ericP: if we don't have an identifier for a row, why do we want to pretend we have an identifier
mhausenblas: need to work out in use cases
ivan: besides saying "we don't
want blank nodes 'cause the linked data doesn't like them", we
need more arguments
... on the wiki page [mhausenblas's request], we need use
cases
<mhausenblas> Michael: some if not all of our use cases (http://www.w3.org/TR/2010/WD-rdb2rdf-ucr-20100608/) require to have linkable resources
ivan: i understand that in many cases i prefer to use an identifier
soeren: perhaps a compromise is to allow one to use a rowid if there is one
ivan: Souri came up with a schems with an R2RML with exceptions
<Souri> +1
ivan: so can't i create a mapping which defines only row (subject) identifiers, they can do it in five lines
<MacTed> default bnode? danger lies ahead...
Souri: yes, you can create a logical table using the rowid
<mhausenblas> PROPOSAL: The DM does not try to define URI-creation, this is topic of and must be done via R2RML
<Zakim> mhausenblas, you wanted to propose a solution
Souri: per ivan's point, you can create a tiny mapping which is 99% direct mapping
<mhausenblas> PROPOSAL: The DM does not try to define URI-creation when there is no PK, this is topic of and must be done via R2RML
+1
<ivan> +1
',' should be a';'
<MacTed> +1, with eric's change
<MacTed> :-)
<MacTed> in fact, it's true -- PK is also temporal...
dmcneil, why is the URI creation when there isn't a PK so differnt from when there is one
dmcneil: why is the URI creation when there isn't a PK so differnt from when there is one?
MacTed: PK can change over time
<Souri> pkey change implies a resource disappears, a new resource appears => not much we can do about it
soeren: so ericP is assuming that PKs are stable and MacTed is assuming they're not
<boris_> nothing lasts forever
mhausenblas: if you want to have reliable URIs, we need to use R2RML
MacTed: if you push URIs out of
DM into R2RML, you've killed DM
... PK may be defined in the schema or interprated in the
application layer
... every DB has to have a row id, but it doesn't have to
expose them
... in my perfect world, there are attributes which are valid
at a point in time
... there's a named graph associated with the identifer and the
named graph is valid for a given time
mhausenblas: resolution requires MacTed's response to action 102
<mhausenblas> ACTION-102?
<trackbot> ACTION-102 -- Ted Thibodeau to sum up the possibilities for generating reliable URIs for DM (to avoid bNodes) on the Wiki -- due 2011-02-15 -- OPEN
<trackbot> http://www.w3.org/2001/sw/rdb2rdf/track/actions/102
<MacTed> ACTION-102?
<trackbot> Sorry... I don't know anything about this channel
<MacTed> silly scroll...
<mhausenblas> http://this-db-really.does-not-exist.org/
<boris_> thanks again Eric!
ADJOURNED
next meeting: next week, next chair: ashok
<mhausenblas> Michael: regrets for the next two meetings (on travel)
The DM does not try to define URI-creation when there is no PK, this is topic of and must be done via R2RML
http://this-db-really.does-not-exist.org/
<mhausenblas> trackbot, end telecon
This is scribe.perl Revision: 1.135 of Date: 2009/03/02 03:52:20 Check for newer version at http://dev.w3.org/cvsweb/~checkout~/2002/scribe/ Guessing input format: RRSAgent_Text_Format (score 1.00) Succeeded: s/stimulated discussion/stimulated email discussion/ Found ScribeNick: ericP Found ScribeNick: mhausenblas Found ScribeNick: ericP Found ScribeNick: mhausenblas Found ScribeNick: ericP Inferring Scribes: ericP, mhausenblas Scribes: ericP, mhausenblas ScribeNicks: ericP, mhausenblas Default Present: +1.314.394.aaaa, mhausenblas, dmcneil, soeren, Ivan, +1.781.273.aabb, EricP, privera, +49.133.6.aacc, MacTed, boris, +1.603.897.aadd, Souri Present: +1.314.394.aaaa mhausenblas dmcneil soeren Ivan +1.781.273.aabb EricP privera +49.133.6.aacc MacTed boris +1.603.897.aadd Souri Regrets: Ashok Nuno Seema Alexandre Richard Agenda: http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2011Feb/0039.html Found Date: 08 Feb 2011 Guessing minutes URL: http://www.w3.org/2011/02/08-rdb2rdf-minutes.html People with action items: herman ivan mhausenb mhausenblas ted[End of scribe.perl diagnostic output]