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Re: FW: Further comment on SPARQL 1.1 Test Cases

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Tue, 25 Sep 2012 11:39:49 +0100
Message-ID: <506189F5.3080600@epimorphics.com>
To: public-rdf-dawg@w3.org


On 25/09/12 10:02, Polleres, Axel wrote:
> Hi Andy,
>
> Working on my part... Some remarks:
>
> 1) Think I spotted a small typo (missing "refer") in
>     http://www.w3.org/2009/sparql/docs/query-1.1/rq25.xml#grammarBNodeLabels
>     and have some more clarifying suggestions there
>
> s/
> Blank node labels are scoped to the SPARQL Request String in which they occur.
> Use of the same blank node label in a request to the same blank node.
> Fresh blank nodes are generated for each request; blank nodes can not be referenced by label across requests.
> /
> Blank node labels are scoped to the SPARQL *query or update operation string* in which they occur.
> *Different* use*s* of the same blank node label in a query or update operation *refer* to the same blank node.
> Fresh blank nodes are generated for each request; blank nodes can not be referenced by label across requests.
> /
>

"SPARQL Request String" is a formally defined piece of terminology to 
cover update and query.

"refer"  edit done.

> The reason for not speaking about a *request* but rather an *update operation* is that
> Given the semantics of updates http://www.w3.org/TR/sparql11-update/#def_datasetQuadPattern
> The skolemization, i.e. blank node creation is "per operation", not "per request", thus,
> the same blank node used across different operations within a single request is not necessarily the same.

We are talking about syntax not execution semantics as in 4.2.3 which is 
about template substitution.

> That is:
>
>   INSERT DATA {GRAPH <g1> {_:b1 :p :o } GRAPH <g2> {_:b1 :p :o } }
>
> (which inserts the same bnode in two graphs)
> is IMO *not* the same as
>
>   INSERT DATA {GRAPH <g1> {_:b1 :p :o } } ;
>   INSERT DATA {GRAPH <g2> {_:b1 :p :o } }
>
> (which inserts two different bnodes into the two graphs)

why?

Document-scope is a clear and systematic policy.

It is per parser run (the grammar defines requests, not operations).

	Andy

>
> Axel
>
>> -----Original Message-----
>> From: Andy Seaborne [mailto:andy.seaborne@epimorphics.com]
>> Sent: Freitag, 21. September 2012 12:00
>> To: public-rdf-dawg@w3.org
>> Subject: Re: FW: Further comment on SPARQL 1.1 Test Cases
>>
>> Parts relating to editing of rq25 done.
>>
>> 	Andy
>>
>> On 20/09/12 09:27, Andy Seaborne wrote:
>>>
>>>> Summarizing, unless anybody disagrees, I suggest the following:
>>>>
>>>>    * adapt editorial suggestion 1) as above in Update
>>
>> (not done - in the update doc)
>>
>>>>    * amend remark 10 in
>>>> http://www.w3.org/2009/sparql/docs/query-1.1/rq25.xml#sparqlGrammar
>>>>      as suggested above in 2)
>>>
>>> Yes
>>
>> Done
>>
>> (longer form used that mentions query and update)
>>
>>>
>>>>    * Reply to Rob that shared blank nodes across
>> QuadPatterns within
>>>> the same insert are allowed and
>>>>      behave as per test case basic-update/manifest#insert-05a
>>>
>>> Yes
>>
>> (This needs to be done.)
>>
>>>
>>>>    * Optionally, we could add a variant of
>>>> basic-update/manifest#insert-05a to the test
>>>>      suite that explicitly covers Rob's example.
>>>
>>> OK.
>>> But we than need to let everyone that has submitted test
>> results about
>>> the change.
>>>
>>>
>>>
>>> I think adding a brief note on id scoping is in order as
>> well: Expand
>>> 19.6 with
>>>
>>> """
>>> Blank node labels are scoped to the request in which they occur.
>>> Use of the the same label referrers to the same blank node. Blank
>>> nodes and fresh blank nodes are generatedA blank label can
>> be used for
>>> each request; blank nodes can not be referenced by label across
>>> documents (requests)
>>>
>>> Additionally, the same blank node can not be used in two different
>>> basic graph patterns in a SPARQL Query or a SPARQL Update
>> pattern (the
>>> WHERE clause).
>>>
>>> The same blank node can occur in different QuadData and QuadPattern
>>> clauses.
>>> """
>>
>> Done - with link as suggested by Axel.
>>
>>>
>>>       Andy
>>>
>>>>
>>>> Best,
>>>> Axel
>>>>
>>>>
>>>> 1.
>>>>
>> http://lists.w3.org/Archives/Public/public-rdf-dawg/2012AprJun/0163.h
>>>> tml
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ________________________________
>>>>
>>>> From: Rob Vesse [mailto:rvesse@dotnetrdf.org]
>>>> Sent: Mittwoch, 19. September 2012 20:03
>>>> To: Polleres, Axel
>>>> Cc: public-rdf-dawg-comments@w3.org
>>>> Subject: Re: Further comment on SPARQL 1.1 Test Cases
>>>>
>>>>
>>>> Yes of course you can forward to the list, I will CC this
>> to the list
>>>> myself
>>>>
>>>> Rob
>>>>
>>>> From: "Polleres, Axel" <axel.polleres@siemens.com>
>>>> Date: Wednesday, September 19, 2012 4:39 AM
>>>> To: Rob Vesse <rvesse@dotnetrdf.org>
>>>> Subject: RE: Further comment on SPARQL 1.1 Test Cases
>>>>
>>>>
>>>>
>>>>           Hi Rob,
>>>>
>>>>           I realiszed that I sent this to you only offlist.
>> Hope it is
>>>> ok for you if I fwd your suggestions with the WG list?
>>>>
>>>>           thanks,
>>>>           Axel
>>>>
>>>>
>>>> ________________________________
>>>>
>>>>                   From: Rob Vesse [mailto:rvesse@dotnetrdf.org]
>>>>                   Sent: Dienstag, 18. September 2012 18:05
>>>>                   To: Polleres, Axel
>>>>                   Subject: Re: Further comment on SPARQL 1.1 Test
>>>> Cases
>>>>
>>>>
>>>>                   Hi Axel
>>>>
>>>>                   Perhaps if the group were to amending the
>> following
>>>> text from 3.1.1 INSERT DATA
>>>>
>>>>                   Variables in QuadDatas are disallowed in
>> INSERT DATA
>>>> requests (see Notes 8 in the grammar
>>>> <http://www.w3.org/TR/sparql11-query/#sparqlGrammar> ).
>> That is, the
>>>> INSERT DATA statement only allows to insert ground triples. Blank
>>>> nodes in QuadDatas are assumed to be disjoint from the
>> blank nodes in
>>>> the Graph Store, i.e., will be inserted with "fresh" blank nodes.
>>>>
>>>>
>>>>                   And add additional text something like
>> the following:
>>>>
>>>>
>>>>                   Per Note 10 in the grammar blank node identifiers
>>>> may be reused across graph blocks in QuadData but users
>> should note
>>>> that distinct fresh blank nodes will be generated for each
>> usage in
>>>> each block.
>>>>
>>>>
>>>>                   That's a little clunky but I'm sure the
>> WG can come
>>>> up with something a little more flowing that gets the
>> clarification
>>>> across, it's primarily just a case of referring back to
>> that note in
>>>> the main query document.
>>>>
>>>>
>>>>                   Thanks,
>>>>
>>>>                   Rob
>>>>
>>>>                                   From: "Polleres, Axel"
>>>> <axel.polleres@siemens.com>
>>>>                   Date: Tuesday, September 18, 2012 7:48 AM
>>>>                   To: Rob Vesse <rvesse@dotnetrdf.org>
>>>>                   Subject: RE: Further comment on SPARQL 1.1 Test
>>>> Cases
>>>>
>>>>
>>>>
>>>>                           Hi Rob,
>>>>
>>>>                           Would you have a specific editorial
>>>> suggestion for a respective explaining text which we could
>> add to the
>>>> Update document?
>>>>
>>>>                           Thanks,
>>>>                           Axel
>>>>
>>>>
>>>>
>>>> ________________________________
>>>>
>>>>                                   From: Rob Vesse
>>>> [mailto:rvesse@dotnetrdf.org]
>>>>                                   Sent: Freitag, 14.
>> September 2012 17:46
>>>>                                   To: Polleres, Axel;
>>>> public-rdf-dawg-comments@w3.org
>>>>                                   Subject: Re: Further comment on
>>>> SPARQL 1.1 Test Cases
>>>>
>>>>
>>>>                                   Hi Axel
>>>>
>>>>                                   Yes this answers my specific
>>>> question but I still think it may be worth the group adding some
>>>> clarifying text to the specification to make the distinction clear
>>>>
>>>>                                   Rob
>>>>
>>>>
>>        From:
>>>> "Polleres, Axel" <axel.polleres@siemens.com>
>>>>                                   Date: Thursday, September 13, 2012
>>>> 11:01 PM
>>>>                                   To: Rob Vesse
>>>> <rvesse@dotnetrdf.org>, "public-rdf-dawg-comments@w3.org"
>> <public-rdf-dawg-comments@w3.org>
>>>>                                   Subject: RE: Further comment on
>>>> SPARQL 1.1 Test Cases
>>>>
>>>>
>>>>
>>>>                                           Hi Rob,
>>>>
>>>>                                           (note that this is not a
>>>> formal reply, but just quickly:)
>>>>
>>>>                                           > 2 - The
>> restriction does
>>>> not apply to updates
>>>>
>>>>                                           holds.
>>>>
>>>>                                           SPARQL1.0 forbade (and
>>>> SPARQL1.1 still forbids this blank nodes to be shared
>> across BGPs, cf.
>>>>
>>>> http://www.w3.org/TR/sparql11-query/#grammarBNodeLabels
>>>>
>>>>                                           The group didn't see a
>>>> reason to put this restriction on QuadPatterns in the head of
>>>> DELETE/INSERT statements in Update (which are different
>> from BGPs in the WHERE clause).
>>>>
>>>>                                           Hope this
>> clarifies matters,
>>>> pleases let us know if this answers your request or
>> whether you still
>>>> expect a formal group reply,
>>>>
>>>>                                           Axel
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ________________________________
>>>>
>>>>                                           From: Rob Vesse
>>>> [mailto:rvesse@dotnetrdf.org]
>>>>                                           Sent: Freitag,
>> 14. September
>>>> 2012 01:39
>>>>                                           To:
>>>> public-rdf-dawg-comments@w3.org
>>>>                                           Subject: Further
>> comment on
>>>> SPARQL 1.1 Test Cases
>>>>
>>>>
>>>>                                           I am working
>> towards getting
>>>> dotNetRDF back to as close to 100% compliance with the
>> current state
>>>> of the SPARQL 1.1 Query and Update specifications as possible and
>>>> have run into one test case which is confusing to me
>> because it seems
>>>> as odd with SPARQL 1.0 behavior.
>>>>
>>>>                                           This is
>> syntax-update-53.ru:
>>>>
>>>>
>>>>                                           PREFIX :
>>>> <http://www.example.org/>
>>>>                                           INSERT DATA {
>>>>                                                         GRAPH<g1> {
>>>> _:b1 :p :o }
>>>>                                                         GRAPH<g2> {
>>>> _:b1 :p :o }
>>>>                                                       }
>>>>                                           Currently my
>> implementation
>>>> rejects this on the grounds that the same blank node is reused in
>>>> different graph patterns.  It was my understanding that the 1.0
>>>> specification forbade this and there are in fact a
>> selection of 1.0
>>>> tests that specifically check that a parser rejects such queries.
>>>>                                           So I assume one of three
>>>> things must be true:
>>>>                                           1 - This restriction has
>>>> been removed in SPARQL 1.1 (if so where does the spec state this?)
>>>>                                           2 - The
>> restriction does not
>>>> apply to updates
>>>>                                           3 - The test case
>> is incorrect
>>>>                                           I would appreciate some
>>>> feedback on this specific test case but also that the
>> working group
>>>> would please make sure the test suite is all up to date
>> and accurate
>>>> (sorry to complain yet about this yet again but it really makes it
>>>> hard to check an implementation if you have to check for
>> each failing
>>>> test whether the test case is actually correct)
>>>>                                           Rob
>>>>
>>>>
>>>>
>>>
>>
>>
Received on Tuesday, 25 September 2012 10:41:32 GMT

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