Re: resources (RDF, that is)

In RDF, nodes, and literals, and blank nodes denote resources.  The section 
you reference is from the introduction, which is well before blank nodes are 
introduced.  Throughout the RDF documentation resource should only be used 
when talking about things in the world, i.e., what is denoted by IRIs, 
literals, and blank nodes in RDF graphs.  This use of resource is consistent 
with common web parlance - URI (Uniform Resource *Identifier*) and IRI 
(Internationalized *Resource* Identifier).  I think that this working group 
should freely use resource with this meaning.

The Jena documentation https://jena.apache.org/documentation/rdf/index.html 
mirrors this setup, more or less.  (See the section "Nodes:...".)  However, 
Jena then goes on to stupidly use Resource to identify the union of IRIs and 
blank nodes and, even worse, to use resource when talking about nodes in an 
RDF graph.  That's a problem with Jena, not RDF or W3C or the web.  This 
working group should never use resource or Resource to identify components of 
RDF graphs.



peter


On 12/17/2014 04:10 PM, Holger Knublauch wrote:
> Yes I agree we need to be consistent with how other W3C specs are written, and
> the term "Resource" is unfortunately overloaded so it's best avoided.
>
> When I have been using these terms here, I was considering them as technical
> entities as used for example in the Jena API, which uses the following class
> hierarchy
>
> RDFNode
>     Literal
>     Resource
>         Property
>
>  From this angle, a node is the generalization of literals and resources.
> Whether the resources also happen to have a corresponding entity in the real
> world is off-topic from this POV. In this interpretation the term "node" means
> "either literal or resource" and the term "resource" excludes literals.
>
> I am just saying this because I believe many other people consuming our
> documents will share the same interpretation. I see that the official specs
> use the term "Resource" to be the graph representation of either a literal or
> IRI, but not a blank node:
>
> http://www.w3.org/TR/rdf11-concepts/#resources-and-statements
>
> which is indeed a very different interpretation than what for example the Jena
> or Sesame APIs do.
>
> So moving forward, I believe the equivalent terms for the API interpretation
> would be
>
> RDFNode (Jena) = node
> Literal = literal
> Blank node = blank node
> URI Resource = IRI (http://www.w3.org/TR/rdf11-concepts/#section-IRIs)
> Resource = DON'T USE FOR NODES
>
> Is there an established term for "IRI or blank node"?
>
> According to this, I believe the wiki pages are full of incorrect (imprecise)
> usages of the term Resource, and we can gradually fix that, but it's more
> important for everyone to be aware that for official specs we need to avoid
> the term "resource" unless we talk about the abstract concept in the world.
>
> (Peter please correct me if I am wrong on my summary).
>
> What puzzles me though is why is the root class in the RDFS meta-model called
> rdfs:Resource and not rdfs:Node?
>
> I also notice that there are borderline usages of the term "resource" even in
> the SPARQL spec, e.g.
>
> http://www.w3.org/TR/sparql11-query/#propertypaths
>
> "Property paths allow for more concise expressions for some SPARQL basic graph
> patterns and they also add the ability to match connectivity of two resources
> by an arbitrary length path."
>
> where they should have used "of two nodes" IMHO plus dozens of other usages of
> "resource" in the same document. For example this usage clearly contradicts
> the official definition that excludes "blank nodes":
>
> "For a vocabulary such as FOAF, where the resources are typically blank nodes"
>
> The temptation to use "resource" will certainly remain strong, and it's easy
> to get this wrong.
>
> Holger
>
>
> On 12/17/2014 2:40, Peter F. Patel-Schneider wrote:
>> In RDF, a resource is an entity in the world (or maybe not in the world).
>> RDF resources can be much more than nodes in an RDF graph. Saying that an
>> RDF resource satisfies a shape/constraint/description is very different from
>> saying that a node in an RDF graph satisfies a shape/constraint/description.
>> If we are talking about resources, we might say that Dick Cheney matches the
>> shape/constraint/description unrepentant.  If we are talking  about nodes,
>> we might say that the node ex:dc in
>>
>>   ex:dc ex:bar 1 .
>>
>> matches the shape/constraint/description exactly one ex:bar and all ex:bar
>> integer.
>>
>>
>> As this is the *RDF* data shapes working group, I would object if we did not
>> use RDF terminology in the correct way.  This means that I would object if
>> any document from the working group used resource in other than its RDF
>> meaning.
>>
>>
>> Peter F. Patel-Schneider
>> Nuance Communications
>>
>

Received on Thursday, 18 December 2014 00:50:42 UTC