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RE: SPARQL / Language spec ready for review [Howard's feedback]

From: Howard Katz <howardk@fatdog.com>
Date: Fri, 8 Oct 2004 12:52:19 -0700
To: "Eric Prud'hommeaux" <eric@w3.org>
Cc: "Dave Beckett" <dave.beckett@bristol.ac.uk>, "Dan Connolly" <connolly@w3.org>, "Andy Seaborne" <andy.seaborne@hp.com>, "Steve Harris" <S.W.Harris@ecs.soton.ac.uk>, "RDF Data Access Working Group" <public-rdf-dawg@w3.org>
Message-ID: <IKEOLCDFPBBPPAHGNKKOMEBIFAAA.howardk@fatdog.com>

Just to add, so as not to impede publication, that I'm satisfied with the
current state of the working draft. I consider this a publishable document.
Again, good work,
Howard

> -----Original Message-----
> From: Howard Katz [mailto:howardk@fatdog.com]
> Sent: Friday, October 08, 2004 10:47 AM
> To: Eric Prud'hommeaux
> Cc: Dave Beckett; Dan Connolly; Andy Seaborne; Steve Harris; RDF Data
> Access Working Group
> Subject: RE: SPARQL / Language spec ready for review [Howard's feedback]
>
>
> Changes look good, Eric,
>
> just two very minor comments:
>
> 1)  a TOC with bolded and non-bolded sections looks very odd to
> me. I don't think I've ever seen that as a stylistic device. I'd
> kill the bolding.
>
> 2)  4.2 Multiple Optional Blocks, first sentence:
>
>     "optionals blocks" -> "optional blocks"
>
> Other than that, nice work!
> Howard
>
> > -----Original Message-----
> > From: public-rdf-dawg-request@w3.org
> > [mailto:public-rdf-dawg-request@w3.org]On Behalf Of Eric Prud'hommeaux
> > Sent: Thursday, October 07, 2004 3:07 PM
> > To: Howard Katz
> > Cc: Dave Beckett; Dan Connolly; Andy Seaborne; Steve Harris; RDF Data
> > Access Working Group
> > Subject: Re: SPARQL / Language spec ready for review [Howard's feedback]
> >
> >
> > Hi Howward, thanks for the feedback and many apologies for the delay
> > in response.
> >
> > All issues should have responses here. Let me know if they are
> > satisfactory, with special indication if they are not satisfactory for
> > 1st WD.
> >
> > On Tue, Oct 05, 2004 at 07:12:27AM -0700, Howard Katz wrote:
> > > Hi Eric,
> > >
> > > This is done off a fairly quick read. I haven't tried to correlate my
> > > feedback against Dave's or anyone else's comments. I'm mostly
> > *not* doing a
> > > lot of nit-picking against spelling errors and other typos at
> > this point,
> > > ie, this is a bit of a higher-level view. This was reviewed
> > against 1.82.
> > >
> > > Hope it's useful,
> > > Howard
> > >
> > > ------------------------
> > > 1 Introduction
> > >
> > > If you're having sub-headings, as in "Document Outline" and "Document
> > > Conventions", wouldn't it be more consistent to sub-number
> > them, as in "1.1"
> > > and "1.2"?
> > 1.97:
> > Outline is gone. Convention is now section 1.1 and in the TOC
> >
> > > ---------------------
> > > 2 Making Simple Queries
> > >
> > > Why not use the same data and query example(s) in the initial
> pictorial
> > > section and the following SPARQL syntax section? That way
> > readers would get
> > > a better feel for how one form translates into the other.
> >
> > Nack. DanC and DaveB (I think) have suggested that we not use bNodes
> > in the first example. Thus the SVG will have to be reworked so it's
> > not worth bringing the following examples to convergence.
> >
> > > -----------------------
> > > last paragraph
> > >
> > > Where doesn't the "andy" come from? I don't see him in the
> graph above.
> > 1.97:
> > [[
> > ...known by Alice (specifically, the person with the mbox
> > alice@work.example)
> > ]]
> >
> > > ------------------------
> > > 2.1 Writing a Simple Query
> > >
> > > Second paragraph, "The terms quoted ..."
> > >
> > > It's a fair distance from this sentence to the actual example
> > below, and the
> > > reader's eyes have to jump down to the example and then find
> > their way all
> > > the way back up again. Why not move this paragraph to either after the
> > > "Data:" section or after the "Query:" section?
> > 1.97:
> > I didn't want to break up the association between Data, Query,
> > Results, so I moved the explanation below the results. It's an after
> > the fact explanation, but that may be clearer.
> >
> > > ----------------------
> > > 2.2 Triple Patterns
> > >
> > > I'm not sure if this requires a bit of reorg or not, but all
> > the examples in
> > > the preceding section have WHERE clauses containing triple
> > patterns, but you
> > > don't introduce the concept until here.
> >
> > Nack. Yeah, but they don't know it yet. I think this is a fairly good
> > solution to the usual tension caused by needing to introduce
> > everything at once.
> >
> > > More importantly, you never say what a triple pattern IS (ie,
> something
> > > along the lines of "A template for describing an s-p-o triple, with
> > > variables representing missing information to be filled in by
> > the query" or
> > > some such. That would be very useful for reader.
> > >
> > > At a minimum, I'd change sentence one from
> > > "The building blocks of queries are triple patterns"
> > > to
> > > "The building blocks of queries are triple patterns, shown as
> > the arguments
> > > of the WHERE clauses in the three queries in the preceding section."
> > >
> > > ---------------------
> > > As well, a brief sentence explaining that triple patterns are
> > delimited by
> > > parentheses ("(" and ")") would be useful.
> > 1.97:
> > [[
> > The building blocks of queries are triple patterns. Syntactically, a
> > SPARQL triple pattern is a subject, predicate and object enclosed in
> > '()'s. The previous example shows a triple pattern with a variable
> > subject (book), a predicate of dcore:title and a variable object
> > (title).
> >
> > ( ?book dcore:title ?title )
> > ]]
> >
> > > --------------------
> > > Paragraph 2, "A triple pattern has either a graph label
> > (URIRef, literal) or
> > > a named variable in each of the subject, predicate and object
> > positions."
> > > Literals of course can only go in the object position. Is it ok
> > to be this
> > > imprecise? (I'm asking because I don't know and don't have a strong
> > > opinion.)
> >
> > Nack. (the question didn't result in a change of text.)
> >
> > A lot of people think that RDF triples should be fully
> > symmetrical. I'm agnostic on this, but don't feel compelled to
> > complicate the spec to reduce the expressivity to RDF. Model
> > conformance can be enforced practically -- people generating queries
> > will not see data that requires literals in the predicate or subject.
> >
> > > ----------------------
> > > Definition: Triple Pattern
> > >       "3" -> "three"
> > ?.??:
> > addressed by Andy's earlier changes to the defintion.
> >
> > > ----------------------
> > > 2.3 Graph Patterns
> > > First paragraph, "This starts with conjunction - the 'and' of triple
> > > patterns."
> > >
> > > It's not clear what "This ..." refers to. How about something
> > like, "We'll
> > > first look at conjunctions, which combine triple patterns using "and".
> > 1.97:
> > [[
> > The keyword WHERE is followed by a Graph Pattern which is made of one
> > or more Triple Patterns. These Triple Patterns are "and"ed
> > together. More formally, the Graph Pattern is the conjunction of the
> > Triple Patterns. In each query solution, each triple pattern must be
> > satisfied with the same binding of variables to values.
> > ]]
> > Better?
> > Sort of an oversimlification (elides OPTIONALs and maybe ORs if they
> > get in the lang).
> > Good enough?
> >
> > > -----------------------
> > > Paragraph starting "There are is a bNode ..."
> > >
> > > 1) "are is" -> "is"
> > ?.??:
> > Andy got it.
> >
> > > 2) I don't understand the final clause in second sentence: ",
> nor to any
> > > query."
> > 1.97:
> > [[
> > There is a bNode [12] in this dataset. Just within the file, for
> > encoding purposes, the bNode is identified by _:a but the information
> > about the bNode label is not in the RDF graph. No query will be able
> > to identify that bNode by name.
> > ]]
> > I wrestled with "identify that bNode by the name _:a" but it seemed
> > worse.
> >
> > > ------------------------
> > > 2.4 Multiple Matches
> > >
> > > "The results of query" -> "The results of a query"
> > 1.97:
> >
> > > ------------------------
> > > 4.2 Multiple Optional Blocks
> > >
> > > Second paragraph, you introduce the concept of outer block.
> > This hasn't been
> > > previously discussed, so it's unclear what this refers to.
> > Please define. As
> > 1.97:
> > [[
> > In this example, there are two, independent optional blocks. Each
> > depends only on variables defined in the non-optional part of the
> > graph pattern.
> > ]]
> >
> > > well, you follow with a hypothetical, "If a new variable is
> > introduced in an
> > > optional block ...", a short "WHERE" snippet example showing
> > this would be
> > > very helpful.
> > 1.97:
> > wordsmithed text to show it from the previous example
> > [[
> > In this example, there are two, independent optional blocks. Each
> > depends only on variables defined in the non-optional part of the
> > graph pattern. If a new variable is introduced in an optional block
> > (as mbox and hpage are introduced in the previous example), that
> > variable can be bound in that block and can not be mentioned in a
> > subsequent block.
> > ]]
> > Slightly awkward, but an improvement in clarity, I think.
> >
> > > ------------------------
> > > 4.3 Optional Matching
> > >
> > > Is there a new syntactic feature introduced here? If so, an
> > example would be
> > > helpful.
> > 1.97:
> > This section is a definition for the syntactic feature introduced
> > in 4.1 by
> > [[
> > Optional portions of the graph may be specified in either of two
> > equivalent ways:
> > ]]
> > I changed the titles around to reflect that:
> > s/4.3 Optional Matching/4.3 Optional Matching -- Formal Definition/
> > s/4.1 Optional binding/4.1 Optional Matching/
> >
> > > ------------------------
> > > 5 Nested Patterns
> > >
> > > It would be useful to introduce this section with a brief
> explanation of
> > > what nesting is. Ie, What is its purpose? Why is it useful?
> >
> > Nack. Punting. I want to wait until the WG decides whether to include
> > OR in the language before attacking this.
> >
> > > ------------------------
> > > Final example in section:
> > >
> > > I don't see a correspondance between the arguments of the
> > SELECT statement
> > > and the headings in the result table. "mbox" would have to be
> > SELECTed to be
> > > output, wouldn't it, and what happened to "name"?
> > 1.97:
> > changed SELECT to make example internally consistent (and still
> sensible)
> > [[
> > SELECT ?foafName ?mbox ?fname ?gname
> > ]]
> >
> > > ------------------------
> > > 8 Choosing What to Query
> > >
> > > Third paragraph, "To execute a query, there needs to be the
> > query and an RDF
> > > graph."
> > > Awkward. How about: "Query execution requires both a query and an RDF
> > > graph."
> > 1.97:
> > [[
> > A SPARQL query must be executed against some real or virtual RDF
> > graph.
> > ]]
> >
> > > -------------------------
> > > 9 Querying the Origin of Statements
> > >
> > > I realize you have a footnote on the first sentence saying the
> > semantics are
> > > undefined, but how about at least a very loose explanation of
> > what a SOURCE
> > > is in the paragraph itself, so the reader at least has a rough idea of
> > > you're talking about? Maybe the footnote could be reworked and
> > moved into
> > > sentence number two? Ie, something like (I'm not claiming this is
> > > technically accurate):
> > >
> > > " ... many RDF data stores augment this with the source of each
> > statement.
> > > Source is at present undefined, but is expected to refer in some
> > > implementation-dependent way to the document of origin,
> > possibly given by a
> > > URL."
> > >
> > > or some such.
> > 1.97:
> > I hit it with my (real or virtual) real-or-virtual hammer.
> > [[
> > While the RDF data model is limited to expressing statements with a
> > subject, predicate and object, many RDF data stores augment this with
> > a notion of the source of each statement. Typically,
> > implementations associate RDF triples or graphs with a URI specifying
> > their real or virtual origin.
> > ]]
> >
> > > ------------------------
> > > 10 Summary of Query Patterns
> > >
> > > Does the bullet "disjunction" correspond to the "alternatives"
> > mentioned in
> > > "6 More Pattern Matching - Alternatives"?  I don't know the ultimate
> > > dispostion of this section but suggest if it stays and is
> > mentioned in this
> > > list, that the terminology be made consistent.
> > ?.??:
> > That reference, and the whole neighborhood, was wiped out by
> > Hurricane Andy.
> >
> > > ------------------------
> > > 11.2 Constructing an Output Graph
> > >
> > > I'm confused by the three boxed snippets. #3 is labelled
> > "Example" -- are
> > > the first two NOT examples as well? What distinguishes #3 from
> > #1 and #2?
> > >
> > > Also, #3 has "PREFIX . . . CONSTRUCT". Are the ellipses part of
> > the syntax??
> > ?.??:
> >
> > > --------------------------
> > > 11.4 Asking "yes" or "no" questions
> > >    -> 11.4 Asking "Yes" or "No" Questions
> > >
> > > I'd also invert sentence #1 and tighten a bit:
> > > "In order just to test whether a query pattern has a query
> > solution or not,
> > > the application can use the ASK form."
> > >    ->
> > > "Applications can use the ASK form to test whether a query
> pattern has a
> > > solution or not."
> > 1.97:
> > [[
> > Applications can use the ASK form to test whether or not a query
> > pattern has a solution.
> > ]]
> >
> > > ------------------------------
> > > 12.1 Standard Operations
> > >
> > > "The SPARQL language provides some of the operations on plain
> > literals, XSD
> > > integers and XSD floats taken from those in XQuery and XPath
> > Functions and
> > > Operators <http://www.w3.org/TR/xpath-functions/>."
> > >
> > > A bit awkward. Do you mean:
> > >
> > > "The SPARQL language provides a subset of the operations on
> > plain literals,
> > > XSD integers and XSD floats defined in XQuery and XPath Functions and
> > > Operators <http://www.w3.org/TR/xpath-functions/>."
> > 1.97:
> > verbatim
> >
> > --
> > -eric
> >
> > office: +81.466.49.1170 W3C, Keio Research Institute at SFC,
> >                         Shonan Fujisawa Campus, Keio University,
> >                         5322 Endo, Fujisawa, Kanagawa 252-8520
> >                         JAPAN
> >         +1.617.258.5741 NE43-344, MIT, Cambridge, MA 02144 USA
> > cell:   +1.857.222.5741 (does not work in Asia)
> >
> > (eric@w3.org)
> > Feel free to forward this message to any list for any purpose other than
> > email address distribution.
> >
Received on Friday, 8 October 2004 19:50:38 GMT

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