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Re: Dataset Syntax - checking for consensus

From: Steve Harris <steve.harris@garlik.com>
Date: Thu, 27 Sep 2012 12:12:07 +0100
Cc: W3C RDF WG <public-rdf-wg@w3.org>
Message-Id: <F9B1EC20-07E9-4B93-B291-3F2BCB8F62CE@garlik.com>
To: Sandro Hawke <sandro@w3.org>
Apologies for the late reply, been very busy recently.

On 2012-09-26, at 00:14, Sandro Hawke wrote:

> I'm not sure how much progress we'll be able to make on dataset semantics tomorrow, so I thought I'd draft some proposals on dataset syntax.   The chairs can put this on the agenda is they like (but it's too short notice for these decisions to be binding yet).  I'm thinking it would be useful to see how close we are to agreement on these issues.
> 
> If you followup with votes, please use -1 for Formal Objection, 0 for abstain, +1 for approve.   Numbers in between are fine, too.
> 
> PROPOSED: We will produce a W3C Recommendation for a dataset syntax, similar to TriG and to SPARQL's named graph syntax.

+0.5 - maybe it's a little early? Doesn't seem that many people in this group have much experience of working with quad/NG formats.

> PROPOSED: We'll request a media-type for this syntax which is different from the media-type for Turtle.  (That is, we will not consider this language to supplant Turtle and take over the name, becoming the new "Turtle", as was once proposed.)

+1

> PROPOSED: Our dataset syntax will allow for the expression of empty named graphs, whatever their semantics might be (to be decided). The syntax is an empty curly-braces expression, as in "<g> { }".

-0.5 - don't see the need for this, and I've never seen it in the wild.

> PROPOSED: Our dataset syntax will have some standard mechanism (to be determined within the next few weeks) through which a Dataset serialization can include some RDF data about the Dataset (that is, some metadata in the form of an RDF graph).

-0.5 - prefer to see a design emerge, rather than design by committee guesswork

> Below, there are groups of proposals which are alternative solutions to a design issue.   If you approve of more than one of the alternatives, please vote "+2" for your favorite.
> 
> * Name of the dataset syntax
> 
> PROPOSED: We will call our recommended dataset syntax "trig", capitalized to Trig as needed.
> PROPOSED: We will call our recommended dataset syntax "TriG", but informally and in the media type, "trig".
> PROPOSED: We will call our recommended dataset syntax "TriG", and use that capitalization everywhere.

0 - pick one, don't care which

> * Use of equals sign, like <g> = { <s> <p> <o> } .  This is not in SPARQL but is in traditional TriG, for compatibility with N3.
> 
> PROPOSED: In our dataset syntax, a "=" MAY appear between the name and the graph.

-1 - optional syntax is bad

> PROPOSED: In our dataset syntax, a "=" MUST appear between the name and the graph.

-1 - people don't do this in the wild

> PROPOSED: In our dataset syntax, a "=" MUST NOT appear between the name and the graph.

+1

> * Use of the "graph" keyword, which MUST be used in SPARQL and MUST NOT be used in traditional TriG.
> 
> PROPOSED: In our dataset syntax, the case-insensitive keyword "graph" MAY appear before the name, in a name-graph pair.
> PROPOSED: In our dataset syntax, the case-insensitive keyword "graph" MUST appear before the name, in a name-graph pair.
> PROPOSED: In our dataset syntax, the case-insensitive keyword "graph" MUST NOT appear before the name, in a name-graph pair.

Either MUST or MUST NOT, pick one - prefer MUST NOT as it's what people do now.

> * Use of curly braces { <a> <b> <c> } around the default graphs.   They MUST be used in traditional TriG, and MUST NOT be used in SPARQL.
> 
> PROPOSED: In our dataset syntax, triples of the dataset's default graph MAY be surrounded by curly braces.

+0

> PROPOSED: In our dataset syntax, triples of the dataset's default graph MUST be surrounded by curly braces.

+1 - to avoid Turtle / TriG confusion.

> PROPOSED: In our dataset syntax, triples of the dataset's default graph MUST NOT be surrounded by curly braces.

-1 - to avoid Turtle / TriG confusion

> * Some designs for carrying for metadata
> 
> PROPOSED: In our dataset syntax, we'll say that metadata goes in the default graph
> PROPOSED: In our dataset syntax, we'll say that the default graph goes inside curly braces and the metadata goes outside curly braces
> PROPOSED: In our dataset syntax, we'll say that metadata goes inside a set curly braces after a keyword "meta".
> PROPOSED: In out dataset syntax, we'll have a keyword "meta" followed by "default" or the name of a named graph, to indicate to readers where the metadata is.

Too early, and none of these is sufficiently similar to common practice in RDF to make me comfortable that it would be the right choice.

In RDF pople do something like:

<> dc:creator "Alice" ;
   dc:date "2012-09-27"^^xsd:date .

so the equivalent would be more like:

<> {
   <> dc:creator "Alice" ;
      dc:date "2012-09-27"^^xsd:date .
}

Wouldn't it?

- Steve

-- 
Steve Harris, CTO
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Received on Thursday, 27 September 2012 11:12:37 GMT

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