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The JSC Technical Working Group discussed the issue of URL vs URI in a paper
discussed by the RDA Steering Committee a few days ago; see
<http://www.rda-jsc.org/sites/all/files/6JSC-TechnicalWG-6.pdf>
http://www.rda-jsc.org/sites/all/files/6JSC-TechnicalWG-6.pdf (page 4 and
following). The RSC accepted recommendation 1 and is taking appropriate
action.

 

The basic conclusion is that a URI is a thing (RDF resource), and a URL is a
string (non-resolvable identifier). This is reflected, I think, in the basic
syntax of RDF: a piece of data in quotes is a string (human-readable) and
all other data in a triple are things (machine-readable URIs). Using
angle-bracket and quote delimiters, the two basic triple syntaxes are:

 

<subjectURI> <propertyURI> <objectURI> .

<subjectURI> <propertyURI> "object string" .

 

I hope this paper is of use - and please let me know (as Chair of the
Working Group) if you disagree with anything.

 

Cheers

 

Gordon

 

From: Bibliographic Framework Transition Initiative Forum
[mailto:[log in to unmask]] On Behalf Of Denenberg, Ray
Sent: 16 November 2015 22:19
To: [log in to unmask]
Subject: Re: [BIBFRAME] Properties of Item proposal

 

Well of course.  You can never guarantee good behavior of an independent
system.  I'm only saying that these are the rules we are supposed to be
playing by.  If I encounter an object of a triple which looks like an RDF
resource URI, I dereference it (requesting RDF), and you refuse the request,
I'd consider that a failure. 

 

Ray

 

From: Bibliographic Framework Transition Initiative Forum
[mailto:[log in to unmask]] On Behalf Of LeVan,Ralph
Sent: Monday, November 16, 2015 4:58 PM
To: [log in to unmask] <mailto:[log in to unmask]> 
Subject: Re: [BIBFRAME] Properties of Item proposal

 

Ray, my VIAF server does provide RDF when asked via content negotiation.
Today it does.  So, today triples that have a VIAF URI in them are legal,
but tomorrow when I break content negotiation they suddenly become illegal?
It's impossible for the coiner of the triple to guarantee some third-party
server behavior.  It's up to the consumer of the triple to identify those
URIs that are pointers to RDF and do whatever seems appropriate.

 

Ralph

 

From: Bibliographic Framework Transition Initiative Forum
[mailto:[log in to unmask]] On Behalf Of Denenberg, Ray
Sent: Monday, November 16, 2015 4:14 PM
To: [log in to unmask] <mailto:[log in to unmask]> 
Subject: Re: [BIBFRAME] Properties of Item proposal

 

Karen,  take this one step at a time.  Suppose I have a triple:

 

     <some subject>   bf:someProperty   <http://someURI>

 

Where again I am using turtle notation and I am explicitly enclosing
http://someURI  in angle braces.   I claim that http://someURI (enclosed in
angle braces) must be dereferenceable as RDF (meaning that there is an RDF
representation of that resource, http://someURI, which may be one of many
representations, and I can get that RDF representation by doing a get on it
requesting RDF via content negotiation).

 

Do you not agree?

 

 

(And you're saying that "RDF resource" is defined in the documents you
cited, but that expression doesn't even occur in any of those documents.
Nowhere. So I'm confused.)

 

 

 

Ray

 

From: Bibliographic Framework Transition Initiative Forum
[mailto:[log in to unmask]] On Behalf Of Karen Coyle
Sent: Monday, November 16, 2015 3:44 PM
To: [log in to unmask] <mailto:[log in to unmask]> 
Subject: Re: [BIBFRAME] Properties of Item proposal

 

 

On 11/16/15 10:37 AM, Denenberg, Ray wrote:

Hi Karen - Yes there certainly is a terminology issue, particularly because
the expression "RDF resource" does not have a formal definition, anywhere
(that I have ever been able to find). 


Actually, Ray, the quotes I gave you in my email are indeed the formal
definition from the W3C specifications. There is probably an even more
formal definition somewhere using virtually unreadable notation, but I think
that what the human-readable documents say is quite clear -- which is that a
resource is "anything that an RDF graph describes" and that it can be either
an IRI or a literal. I agree with you that folks often refer to IRIs as
resources as opposed to literals, but that's a misnomer. Another way of
saying this is "string vs. thing" but there's probably some ambiguity in
that as well. But most importantly, as I said below, nowhere have I
encountered any statements that there is any distinction made that what one
obtains upon dereferencing must be "RDF". In fact, I don't know what that
actually means.

Your http://hdl.loc.gov/loc.pnp/cph.3g11323, which very clearly follows the
rules for an IRI (and IRIs do not need to be dereferenceable) is an IRI.
What it does or does not dereference to does not change that. You can treat
an IRI as a literal string (I don't think there's anything in RDF to prevent
that) -- and therefore indicate that you don't intend it to be actionable as
an IRI. However, again, your distinction of "imply that you can retrieve RDF
by dereferencing" is not familiar to me.

kc

However, whenever I encounter the expression it seems to be used in the
sense that I'm using it.   Which is this:

In any RDF triple the object is a literal or an RDF resource.  A literal is
of course a resource; and I am making a distinction between "resource" and
"RDF resource".  

So, the object of a triple is either:

1.       a literal, in which case it's enclosed in quotes (assuming turtle
serialization); or   

2.       not enclosed in quotes, in which case it is an RDF resource URI
(either enclosed by curly braces or using namespace prefix notation), or a
blank node id.   

 

For case 2, the URI can be dereferenced resulting in an RDF description or
if it is a blank node it points to an RDF description. 


Do you agree (so far)?  If you think I'm using the expression "RDF resource"
incorrectly then what is your definition?  If you think "RDF resource" and
"resource" mean the same thing, I disagree, but then, I could be wrong,
since "RDF resource" has no formal definition.  But I'm using it in the
sense that I see it used. 

 

Anyway, having said all that, getting back to the example at hand

 

      bf:electronicLocator  [

                 a    bf:ElectronicLocator ;

                  rdf:value   "http://hdl.loc.gov/loc.pnp/cph.3g11323
<http://hdl.loc.gov/loc.pnp/cph.3g11323%94> " ] ;

 

I maintain that it would be incorrect to instead say:

 

bf:electronicLocator  <http://hdl.loc.gov/loc.pnp/cph.3g11323
<http://hdl.loc.gov/loc.pnp/cph.3g11323%94> " >

 

because that would imply that you can retrieve RDF by dereferencing
http://hdl.loc.gov/loc.pnp/cph.3g11323 , which (as far as I know) you can't.

 

Ray

 

 

From: Bibliographic Framework Transition Initiative Forum
[mailto:[log in to unmask]] On Behalf Of Karen Coyle
Sent: Sunday, November 15, 2015 8:30 PM
To: [log in to unmask] <mailto:[log in to unmask]> 
Subject: Re: [BIBFRAME] Properties of Item proposal

 

 

On 11/12/15 12:05 PM, Denenberg, Ray wrote:

Hi Joseph - thanks for the comments and questions.  I want to address two
points, while we are still discussing the other suggestions.

 

bf:electronicLocator is, at present, conceived to be a datatype property;
its expected value is a literal.  We could change that to an object property
if that's what people want, however, the URI would still be a literal,
because it is not an RDF resource.   In the example, the electronic locator
is http://hdl.loc.gov/loc.pnp/cph.3g11323 and this is not an RDF resource.
(By RDF resource, we mean, you can dereference the URI and get RDF in
response. You can't for this URI.) 


Ray, can you say more about this concept of a non-resource? AFAIK, many URIs
do not dereference to  "RDF in response", but they are still considered
resources in RDF. I'm looking at:

"90. Resource
In an RDF context, a resource can be anything that an RDF graph describes. A
resource can be addressed by a
<http://www.w3.org/TR/2013/NOTE-ld-glossary-20130627/#uniform-resource-ident
ifier> Unified Resource Identifier (URI)." [1]

"Any  <http://www.w3.org/TR/rdf11-concepts/#dfn-iri> IRI or
<http://www.w3.org/TR/rdf11-concepts/#dfn-literal> literal denotes something
in the world (the "universe of discourse"). These things are called
resources. Anything can be a resource, including physical things, documents,
abstract concepts, numbers and strings; the term is synonymous with "entity"
as it is used in the RDF Semantics specification [
<http://www.w3.org/TR/rdf11-concepts/#bib-RDF11-MT> RDF11-MT]."[2]

There is similar language in the RDF 1.1 primer. [3]

This might be a terminology issue, but even accepting a different
terminology, I'm not aware of any distinction where a response to the
dereferencing of an IRI must be RDF (meaning? ntriples? JSON-LD?) rather
than any RDF:resource (e.g. a jpeg file, an html file, an avi file). 

kc
[1] http://www.w3.org/TR/2013/NOTE-ld-glossary-20130627/#resource
[2] http://www.w3.org/TR/rdf11-concepts/#resources-and-statements
[3] http://www.w3.org/TR/rdf11-primer/

If bf:electronicLocator were to be redefined as an object property, then
instead of this:


 

 <http://bibframe.example.org/item/item5>
<http://bibframe.example.org/item/item5>       

          a                                        bf:Item ;

          bf:electronicLocator      "http://hdl.loc.gov/loc.pnp/cph.3g11323
<http://hdl.loc.gov/loc.pnp/cph.3g11323"> "  ;

..

 

It might look like this:


 

 <http://bibframe.example.org/item/item5>
<http://bibframe.example.org/item/item5>       

          a                                        bf:Item ;

          bf:electronicLocator  [

                                                   a    bf:ElectronicLocator
;

                                                    rdf:value
"http://hdl.loc.gov/loc.pnp/cph.3g11323
<http://hdl.loc.gov/loc.pnp/cph.3g11323%94> " ] ;

      ..

 

Where here we now have defined class bf:ElectronicLocator, but the URI is
still a literal.

 

 

Second, should bf:itemOf (property of item) have a reciprocal property,
bf:hasItem (property of Instance).

I don't know; opinions are welcomed on this question.  We did not include it
in the draft for this reason: an item knows (or should know) what Instance
it is an Item of.  An Instance in general does not know the existence of all
items that claim to be an item of that Instance. So if there were to be a
property bf:hasItem, it could be used within an Instance to point to all
items that that Instance knows about with the disclaimer that it doesn't
claim to point to all its items. If, as such, this would be useful then we
can add the property.  (The same dilemma applies to instanceOf and
hasInstance. And granted, these are both included in BIBFRAME 1.0.)

 

Ray

 

 

From: Bibliographic Framework Transition Initiative Forum
[mailto:[log in to unmask]] On Behalf Of Joseph Kiegel
Sent: Tuesday, November 10, 2015 1:39 PM
To: [log in to unmask] <mailto:[log in to unmask]> 
Subject: [BIBFRAME] Properties of Item proposal

 

Items in BIBFRAME may serve different purposes, which is not addressed in
the Items proposal.  A relatively narrow purpose is to support the user task
obtain, while a more complex one is to support a working circulation system.
The properties elaborated in the proposal are not sufficient even for the
user task obtain.  Here are comments on them.

 

bf:electronicLocator:  should the expected value be a URI?  It seems odd to
express URLs as literals in linked data.

 

 

bf:heldBy and bf:subLocation:  the MARC holdings format and many library
systems recognize three levels of location information: organization,
library and sublocation within a library.  BIBFRAME should support the same
number of levels:  for example, it should add a property such as
bf:location, which is intermediate between bf:heldBy and bf:subLocation.  

 

bf:heldBy University of Washington Libraries

bf:location:  Art Library

bf:subLocation:  Reference stacks

 

bf:heldBy University of Washington Libraries

bf:location:  Engineering Library

bf:subLocation:  Reference stacks

 

Without bf:location, reference or general stacks locations in different
buildings appear to be the same.

 

 

bf:itemOf:   is a reciprocal property needed?  For example, bf:hasItem, a
property of bf:Instance with an expected value of bf:Item.

 

 

Two properties are lacking from the proposal:  bf:itemStatus and
bf:circulationCharacteristic

 

bf:itemStatus:  it is crucial to inform users of the status of an item, e.g.
available, checked out, missing, withdrawn, at the bindery, etc.

 

bf:circulationCharacteristic:  another important aspect of materials is the
general policy that governs them, e.g. circulating or library use only.  It
is tempting to try to include this characteristic in bf:itemStatus, but they
are independent aspects.  LUO materials may be missing, at the bindery or
even checked out (e.g. faculty loans of reference materials).  

 

 

 

-- 
Karen Coyle
[log in to unmask] <mailto:[log in to unmask]>  http://kcoyle.net
m: +1-510-435-8234
skype: kcoylenet/+1-510-984-3600

 

-- 
Karen Coyle
[log in to unmask] <mailto:[log in to unmask]>  http://kcoyle.net
m: +1-510-435-8234
skype: kcoylenet/+1-510-984-3600