Re: RDF 1.1 Primer

Pierre-Antoine,

Thanks for this extensive review, very helpful.
Responses inline.

Guus

On 25-11-13 21:40, Pierre-Antoine Champin wrote:
>
> Hi all,
>
> as per my action last week, here is my review of the Primer :
>
> * section 1, issue 2 "do we really need a roadmap section..." I think not.

Now deleted.

>
> * section 3 : unlinke Pat, I'm ok with the "informal" examples, but it
> should probably be made clearer that it is what they are, informal. This
> is probably an occasion to present the notion of abstract/concrete syntax.
> ** may be the pointy brackets should be replaced by quotes, making the
> terms less IRI-like, and so more obviously informal

We'll make it much more explicit that this is informal. I'm a bit 
hesitant to talk about "abstract syntax".

> ** <This video document> didn't please Pat; I'm assuming that the word
> "This" is contributing to that, as it may be interpreted as a self
> reference to the graph at hand? How about "That video document"?

See response to Pat.

>
> * section 3.3 "The RDF Concepts document provides a list of datatypes" :
> I would add "a (non exhaustive) list of datatypes", (with the
> parenthesis) to prevent the wrong interpretation that those datatypes
> are the only ones usable with RDF

Added.

>
> * section 3.4 Bland nodes : I share most of Pat's concerns in this section
> ** "anonymous resource" is misleading, it reads indeed as a different
> kind of resource; I would rephrase in the spirit of "resources for which
> we don't have nor want to create an IRI"
> ** I agree with Pat that the example is unlikely... I like his example
> with the Cypress.
> ** I also find it a bit extreme to state that blank nodes are rarely
> used or should not be used; this note should probably be removed; it
> really the account of blank nodes in Concepts or Semantics is deemed
> "scary", such a reassuring note should be present in *those* documents

Agreed, see response to Pat.

> * sectio, 3.5 Multiple graphs: is it intended that the examples IRIs are
> sometimes in example.com <http://example.com>, and sometimes in
> example.org <http://example.org> ? If there is a reason to it, it should
> be made clearer. If not, then this should probably be removed.

Oops, that was unintentional. Fixed.

>
> * section 4 RDF Vocabularies :
> ** I agree with Pat that FOAF (or any other vocabulary) should not be
> called a schema. A disambiguation note would probably be useful here,
> explaining that the term "schema" in the RDF world does not mean the
> same as in the XML or RDB world, and should probably never have been
> used in the first place, as it is often *very* misleading, as my next
> remark shows.

All instances of the term "schema" have been removed, except for the 
names RDF Schema and schema.org.

> ** "subject and object of this property must be resources of class
> ex:Person" is misleading. Replace "must be" by "is". The current
> phrasing reads like it would be illegal to state <#bob> foaf:name
> <#alice> and to *not* state that <bob> a foaf:Person. This is a very
> common misunderstanding about RDFS, so we must be very careful not to
> give this impression.
> Just below, you write "to model groups of resources that can act as
> subject or object". This (the word "can", especiallyà is misleading
> again, as no resource is ever forbidden to act as subjet or object of
> any property. Furthermore, I agree with Pat that this phrasing is
> strange, and I like his proposal better.

Rephrased, see response to Pat. Some work still needs to be done on the 
text, though.

>
> * table in section 4 : I propose that the syntactic form for Class be "s
> rdf:type rdfs:Class", and that the description be "s is and RDF class".
> Same for property. Agreed, this is a shortcut (rdfs:Class can
> technically be used in other triples) but it is more homogeneous with
> the rest of the table, and in my opinion easier to grasp.

Good point. Changed accordingly.

>
> * section 5.1 Turtle, paragraph aboutl lines 1-6
> ** IRI should be used instead of URI
> ** "The "base" prefix is used if no prefix is provided" this is
> misleading; the base prefix is used for relative URIs inside pointy
> brackets, while prefixed names have no brackets. I would rephrase the
> whole section in the following spirit :
>
> 'In Turtle, IRIs are enclosed in pointy brackets <>. Relative IRIs are
> resolved agains a base IRI, specified in line 1.
> 'The following lines define IRI prefixes (such as foaf:), that can
> further be use prefixed names (such as foaf:Person) instead of full IRIs.
> 'The corresponding IRI is constructed by replacing the prefix with its
> corresponding IRI (in this example, foaf:Person stands for
> <http://xmlns.com/foaf/0.1/Person>).

Thanks for the text suggestion. Adopted.

>
> Also, would'nt it be better to use SPARQL-like prefixes, as they are
> compatible with SPARQL, precisely? (but granted, they would break
> compatibility with older Turtle parsers, so I'm not sure about it).

Hmm, also not sure. Recorded as an issue in the text.

>
> * section 5.1 Turtle, paragraph about line 9 : I would elicit the fact
> that it should be read "bob (is) a Person"

Added.

>
> * section 5.1 Turtle, paragraph about string literals : why not use the
> string "Leonardo da Vinci" as an example, since it is present in the
> example?

You're right, changed.

> And furthermore, it is confusing afterwards to use "Leonardo da
> Vinci"@it as an example, as it does not appear in the example. Or should
> it?

No, ie doesn't and would prefer not to add. Therefore changed the 
example to the French version of Leonardo's name.

> Finally, in "The datatype of language-tagged strings is not specifed
> explictly in Turtle", I would replace "not" by "never".

Done.

>
> * section 5.3 Other concrete syntaxes : it is not true that RDF/XML was
> the only official concrete syntax: RDFa was already recommended by the W3C.

Right. Changed to "RDF/XML was the only normative syntax for RDF when RDF
1.0 was published in 2004.".

> * section 6  Semantics : not sure what you plan to do with the
> ex:Marriage example, but I'm affraid this is a very exotic feature that
> will not appeal to many readers. A more interesting feature (IMO) would
> be to show how a resource can be treated both as a class and as an instance.

Hmm, marriage is the standard example in all DB 101 courses (because the 
relation has properties of its won). But I agree a class/instance 
example would be more interesting. Will mark this as a todo issue.

>
> * Annex A : I didn't check if all the examples provided the same data as
> the Turtle (resp. Trig) example, but that would be a good idea. It seems
> that the multi-graph JSON-LD does not contain the triples from the
> default graph.

Well, it was the intention that it should produce exactly the same 
triples. Will check.

>
> * Annex A.2 : I think a third example, using "simple" JSON with a
> slightly more complex @context, would nicely illustrate how JSON-LD can
> leverage "idiomatic" JSON to RDF. If you think that is a good idea, I
> volunteer to write that example.

OK, thanks for the offer!

>    pa
>
>
> On Wed, Nov 20, 2013 at 12:21 AM, Guus Schreiber <guus.schreiber@vu.nl
> <mailto:guus.schreiber@vu.nl>> wrote:
>
>     All,
>
>     Yves, and I think that the Primer is ready for a first round of review
>     by the WG. The Editor's Draft is here:
>
>     https://dvcs.w3.org/hg/rdf/raw-file/default/rdf-primer/index.html#
>
>     We are still working on Sec. 7 (RDF Data), but would welcome comments on
>     the rest.
>
>     Guus
>
>

Received on Thursday, 28 November 2013 11:45:48 UTC