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Re: Review: SPARQL 1.1 Federated Extensions

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Mon, 28 Feb 2011 18:44:10 -0500
Message-ID: <4D6C334A.7030108@thefigtrees.net>
To: Carlos Buil Aranda <cbuil@fi.upm.es>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>, Axel Polleres <axel.polleres@deri.org>
My original comment was asking how 4.1 and 4.3 are related. I'm still 
not sure I understand; you seem to say that they are alternatives for 
one another, but I don't see that.

4.1 deals with the translation from grammar to algebra and then 
evaluation of algebra. I'm not sure what 4.3 is saying; for instance, it 
uses ep(i) and then defines it, but I can't seem to make sense of the 
use and definition of it.

Also, whereas the evaluation algorithm in 4.1 (3.1 now) talks about 
invoking the SPARQL protocol (which makes sense to me), the definition 
in 4.3 (3.2 now) doesn't seem to say anything about how a pattern gets 
evaluated against a remote endpoint. So as it stands now, if they _are_ 
alternatives, I'd prefer to remove 3.2 and stick with 3.1, while 
cleaning up 3.1 as per my comments in the original review.

Lee


On 2/28/2011 5:31 PM, Carlos Buil Aranda wrote:
> Hi all,
>
> I have a question regarding your comments about sections 4.1 Definition
> of Service and 4.3 Service evaluation semantics (now sections 3.1 and
> 3.2). In section 3.1 the evaluation of SERVICE is defined using an
> algorithm meanwhile in section 3.2 I use an algebraic expression.
> Section 3.1 received several comments from you both (Axel and Lee) and
> section 3.2 none. Both sections describe the same, the service
> semantics. I'd prefer to remove section 3.1 and leave only section 3.2
> for describing SERVICE semantics. For me it contains a clearer and
> cleaner definition. The only thing missing is the silent op function,
> but I would add it in the next days. I need to think a little bit about
> it. Also, a bit more textual explanation would be needed.
>
> any comment?
>
>
>>
>> * 4.1 I don't think this should restate the text from SPARQL 1.1
>> Query. It should only include the new additions to the algorithm,
>> along with a clear reference to where the new bit is inserted.
>>
>> * 4.1 This doesn't seem to take SILENT into consideration.
>>
>> * 4.1 The algebra expression given for an example seems to be
>> completely incorrect. Can this be checked?
>>
>> * 4.1. I think the definition is unclear as written. Specific
>> questions I have are:
>> * What is "B"?
>> * What does "if IRI is a SPARQL service" mean?
>> * What is omega?
>>
>> * Remove 4.2.
>>
>> * I'm unclear as to how 4.1 relates to 4.3?
>>
>> * Remove 4.4
>>
>> * 4.5 needs to be explained in the context of 4.1 and 4.3.
>>
>> * The conformance section needs to be tuned specifically to federated
>> query.
>>
>>
>> Lee
>>
>>
>
>
Received on Monday, 28 February 2011 23:44:49 GMT

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