Re: Comments on Eric's Section 2

On 7 Nov 2010, at 12:22, Juan Sequeda wrote:
> Have you seen the new version:
> http://www.w3.org/2001/sw/rdb2rdf/directGraph/alt

Yes -- and it's great that many of my comments from a few days ago are  
addressed.

But to repeat: I find the style, conciseness, use of examples, and  
handling of corner cases better in Eric's version. It gets more  
information across in less words. I think that a minimalist style --  
be as clear as possible in as little words as possible -- is highly  
appropriate for a technical specification. It appears that Eric is  
good at writing that kind of prose.

> For the record, it was not Marcelo/Juan's decision to fork document  
> in the first place.

In that case I apologize for saying that it was your decision. I got a  
wrong impression from the Semantics teleconference minutes.

Richard



>
>
> Juan Sequeda
> +1-575-SEQ-UEDA
> www.juansequeda.com
>
>
> On Sat, Nov 6, 2010 at 11:13 PM, Richard Cyganiak  
> <richard@cyganiak.de>wrote:
>
>> All,
>>
>> I'm travelling and a few days behind the latest RDB2RDF news and  
>> continue
>> to be baffled by events, especially the decision by Ashok and  
>> Thomas to
>> abandon work on Eric's version of the direct mapping document in  
>> favour of
>> the Juan/Marcelo version.
>>
>> I had a checkout of Eric's version and reviewed it while on the  
>> plane,
>> which now apparently was a waste of time, but I'll share the comments
>> anyway.
>>
>> Having read both documents, I think that Eric's is better written,  
>> gets the
>> same information across in a more concise and accurate way, and has  
>> just
>> sufficient examples to make everything clear. It deals with corner  
>> cases
>> that are not addressed in the /alt version. Altogether I think that  
>> it's
>> superior to the /alt document. I still don't understand why Juan  
>> and Marcelo
>> have forked the document in the first place, but seriously I don't  
>> think
>> that their changes have led to a superior Section 2 -- their  
>> version simply
>> says the same things in a generally harder-to-digest style in more  
>> words.
>>
>> For the record: If the issues that I list below can be addressed,  
>> along
>> with the three from my other email I sent earlier, then I support
>> publication of an FPWD that consists of:
>>
>> - Eric's sections 1 and 2
>> - followed by Eric's set semantics based formal approach
>> - and Juan/Marcelo's datalog based formal approach
>> - with an issue box explaining that both of these are work-in- 
>> progress
>> candidates for the formal semantics.
>>
>> And that's the last thing I intend to say about the direct mapping  
>> thingy
>> until the three editors have managed to present the WG with a  
>> single version
>> of the document endorsed by all of them.
>>
>> Best,
>> Richard
>>
>>
>> Comments on Eric's draft
>>
>> 1. Section 2.1 is IMHO unnecessary and confuses more than it helps.  
>> I would
>> move its first two sentences into the Introduction, and remove the  
>> rest, in
>> particular the SPARQL example. The same goes for the SPARQL example  
>> in 2.4,
>> I would remove it. SPARQL query evaluation is a completely  
>> different topic
>> and requires a ton of knowledge that is not essential for  
>> understanding the
>> default mapping, so I honestly don't see how this helps the average  
>> reader.
>>
>> 2. Section 2.2: The predicate for reference triples is described  
>> as: “an
>> IRI composed of the stem, table name and column name and value for  
>> each
>> column in the foreign key”. I don't understand why it says “and  
>> value”? The
>> object is described as: “the subject created for the referred  
>> triple”. Do
>> you mean “referenced row”?
>>
>> 3. Please provide a rationale for the “#_” at the end of generated  
>> IRIs in
>> the text. In my opinion, this is entirely unnecessary and a useless
>> complication. I see there is an issue box for that in the document,  
>> that's
>> great, but if you want to have the “#_” thing in the FPWD then  
>> there should
>> be text stating why it is necessary. My proposal for FPWD would be to
>> s/#_//g and state in the issue box that this is subject to more  
>> discussion.
>>
>> 4. Inconsistency: Section 2.2 states that predicate IRIs have  
>> hashes, while
>> all the examples have slashes.
>>
>> 5. You should define the terms “row IRI” or “row identifier” and  
>> “column
>> IRI”, and use them throughout, instead of saying sloppy things like  
>> “a IRI
>> composed of the stem, table name and column name” or “the subject  
>> of the
>> referenced row”. I think this is done pretty well in the  
>> directGraph/alt
>> draft.
>>
>> 6. Why a reference to [SQL99]? I thought we had agreed to use SQL  
>> Core
>> 2008? You can copy the reference from the R2RML draft.
>>
>> 7. Both “URI” and “IRI” are used. I suppose it should be “IRI”  
>> everywhere?
>>
>> 8. In order to have an improved narrative in the section titles, I  
>> propose
>> splitting 2.2 into one section “Identifiers for rows and columns”  
>> and one
>> section “Row mapping rules”. (Not essential for FPWD)
>>
>> 9. Section 2.5: “Hierarchies” can refer to many things in an SQL  
>> context,
>> so it's a bit hard to figure out what the section refers to. The  
>> first
>> sentence should perhaps talk about “hierarchies of tables that  
>> represent
>> specializations of the same concept” or something similar. The  
>> People table
>> should perhaps be removed from the example, because it is not  
>> relevant to
>> the example and makes understanding the relevant parts of the example
>> harder.
>>
>> 10. Given that the question of many-to-many table mappings is an open
>> issue, there should be at least a section about it that is empty  
>> except for
>> an issue box. (I have more to say on this topic, but don't expect  
>> that
>> discussion to be resolved before FPWD)
>>
>> 11. See my comments to Juan and Marcelo asking for inclusion of  
>> table IRIs
>> and of a triple that associates each row to its table. I'd really  
>> like to
>> see a proposal for this in the FPWD, but at least an issue box  
>> would be
>> essential. I note that the directGraph/alt version already has this.
>>
>>
>>

Received on Sunday, 7 November 2010 05:37:16 UTC