[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: RE: [xdi] Re: XDI subjects (was Groups - XDI RDF v8 Comments-Barnhill)
In proofing my rich-HTML-link-as-X3 in the example at the end of this last
message, I realized I missed a square bracket at the very end (one reason I
love X3 Simple ;-). The example should be:
...blah blah [$[$type$xsd$string["some literal text
here"]][$uri["http://example.com/some/target"]][$uri$https["https://example.
com/some/target"]][$is[@!F83.62B1.44F.2813!1234]]] blah blah...
Converted to X3 Simple, the link itself would be:
$
$type$xsd$string
"some literal text here"
$uri
"http://example.com/some/target";
$uri$https
"https://example.com/some/target";
$is
@!F83.62B1.44F.2813!1234
=Drummond
> -----Original Message-----
> From: Drummond Reed [mailto:drummond.reed@cordance.net]
> Sent: Wednesday, March 19, 2008 5:40 PM
> To: 'Kermit Snelson'
> Cc: 'Markus Sabadello'; 'Giovanni Bartolomeo'; barnhill_william@bah.com;
> xdi@lists.oasis-open.org
> Subject: RE: [xdi] Re: XDI subjects (was Groups - XDI RDF v8 Comments-
> Barnhill)
>
> Kermit, I agree with you that RDF itself doesn't allow literals as
> subjects
> (why they made that decision is a topic we'll put out of scope for now).
> However I doesn't make sense to me that the "proper XDI mapping" of the
> HTML
> link...
>
> Blah blah <a href="http://example.com/some/target";>some literal text
> here</a> blah blah
>
> ...would be:
>
> XDI subject = "http://example.com/some/target";
> XDI predicate = $html$a
> XDI object = "some literal text here"
>
> The reason is that I don't think that's the actual RDF graph being
> expressed. An HTML link embedded in one page pointing to another Web page
> would be the following graph:
>
> ---------------------- -----------------------
> | HTML link text | ======> | Target page |
> ---------------------- -----------------------
> RDF subject RDF predicate RDF object
>
> That would map to:
>
> XDI object = "some literal text here"
> XDI predicate = $uri
> XDI subject = "http://example.com/some/target";
>
> However, building on Markus' suggestion, it does appear that there is a
> clean way to express this so that it does not force us to have a literal
> as
> an XDI subject. In X3 Simple, it would be the following:
>
> $
> $type$xsd$string
> "some literal text here"
> $uri
> "http://example.com/some/target";
>
> This especially makes sense since "$" by itself represents the self-
> context
> -- literally, "here and now", which is what every HTML link actually
> represents -- a link from the point where you see the link to the target
> resource. So in English-pseudo-X3 this would translate to something like:
>
> In the current context
> the text
> "some literal text here"
> has the URI
> "http://example.com/some/target";
>
> That completely solves the problem. We still get unambiguous HTML-to-XDI-
> RDF
> translation of any HTML link together with the ability to extend the
> semantics of the link as we discussed earlier in the thread. So a
> corrected
> example of such a "rich XDI link" we discussed earlier in the thread would
> be:
>
> Blah blah [$[$type$xsd$string["some literal text here"]
> [$uri["http://example.com/some/target";]]
> [$uri$https["https://example.com/some/target";]]
> [$is[@!F83.62B1.44F.2813!1234]] blah blah
>
> =Drummond
>
> > -----Original Message-----
> > From: kermit.snelson@gmail.com [mailto:kermit.snelson@gmail.com] On
> Behalf
> > Of Kermit Snelson
> > Sent: Tuesday, March 18, 2008 12:58 PM
> > To: Drummond Reed
> > Cc: Markus Sabadello; Giovanni Bartolomeo; barnhill_william@bah.com;
> > xdi@lists.oasis-open.org
> > Subject: Re: [xdi] Re: XDI subjects (was Groups - XDI RDF v8 Comments-
> > Barnhill)
> >
> > There are at least three reasons, in my opinion, why XDI/RDF subjects
> > can't be literals:
> >
> > 1) RDF itself doesn't allow literals as subjects:
> >
> > http://www.w3.org/TR/rdf-concepts/#dfn-subject
> >
> > 2) The proper XDI mapping of:
> >
> > Blah blah <a href="http://example.com/some/target";>some literal text
> > here</a> blah blah
> >
> > would be:
> >
> > XDI subject = "http://example.com/some/target";
> > XDI predicate = $html$a
> > XDI object = "some literal text here"
> >
> > and the corresponding inline X3, with the additional predicates in
> > Drummond's example, would be something like:
> >
> > Blah blah [http://example.com/some/target[$html$a["some literal text
> > here"]]
> >
> [$uri$https[https://example.com/resolvable/uri]][$is[@!F83.62B1.44F.2813!1
> > 234]]
> > blah blah
> >
> > 3) Allowing literals as subjects doesn't make logical sense. Consider
> > the following:
> >
> > <"http://example.com/number/of/hours/in/a/day";>
> > <http://english.com/is";> <"24">.
> > <"http://example.com/number/of/beers/in/a/case";>
> > <http://english.com/is";> <"24">.
> >
> > So far, so good. But to assert the following:
> >
> > <"24"> <"http://english.com/is";>
> > <"http://example.com/number/of/hours/in/a/day";>.
> > <"24"> <"http://english.com/is";>
> > <"http://example.com/number/of/beers/in/a/case";>.
> >
> > is to assert some substantial connection between the number of hours
> > in a day and the number of beers in a case, which is fallacious.
> >
> > =Kermit
> >
> > On 3/18/08, Drummond Reed <drummond.reed@cordance.net> wrote:
> > >
> > >
> > >
> > >
> > > First, let me be clear: I'm not a big fan of using literals as
> subjects,
> > and
> > > I don't have any compelling use cases for it (see below for the only
> one
> > > I've been thinking about). It was Giovanni who seemed to have a reason
> > for
> > > using literals as subjects.
> > >
> > >
> > >
> > > Second, I agree, a literal as a subject can't be changed or it becomes
> a
> > new
> > > subject from an XDI standpoint.
> > >
> > >
> > >
> > > Now, here's the one thing that's had me thinking about literals-as-
> > subjects
> > > for a long time - take a standard HTML link tag:
> > >
> > >
> > >
> > > Blah blah <a
> > > href="http://example.com/some/target";>some literal text
> > > here</a> blah blah
> > >
> > >
> > >
> > > If you wanted to turn this into an XDI statement, the only logical
> > mapping
> > > that seems to make sense is:
> > >
> > >
> > >
> > > XDI subject = "some literal text here"
> > >
> > > XDI predicate = $uri
> > >
> > > XDI object = "http://example.com/some/target";
> > >
> > >
> > >
> > > In other words, were you to replace HTML <a> tags with X3 within an
> HTML
> > > document, the above link would look like:
> > >
> > >
> > >
> > > Blah blah ["some literal text
> > > here"[$uri["http://example.com/some/target";]]] blah blah
> > >
> > >
> > >
> > > That's pretty cool, because now you have a way of embedding really
> rich
> > > semantics into ordinary web pages and web links. As a simple example,
> > image
> > > being able to make the above simple link into a compound statement,
> > which
> > > includes: a) an alternate HTTPS URL for the target resource, and b) a
> > > persistent XRI synonym for the resource:
> > >
> > >
> > >
> > > Blah blah ["some literal text
> > > here"[$uri["http://example.com/some/target";]]
> > >
> >
> [$uri$https["https://example.com/some/target"]][$is[@!F83.62B1.44F.2813!12
> > 34]]
> > > blah blah
> > >
> > >
> > >
> > > Net net: it's the ability to put XDI statements inline in ordinary
> HTML
> > and
> > > other markup formats that's the strongest use case I've seen so far
> for
> > > being able to treat literals as XDI subjects.
> > >
> > >
> > >
> > > =Drummond
> > >
> > >
> > >
> > >
> > >
> > >
> > > ________________________________
> > >
> > >
> > > From: markus.sabadello@gmail.com [mailto:markus.sabadello@gmail.com]
> On
> > > Behalf Of Markus Sabadello
> > > Sent: Tuesday, March 18, 2008 9:30 AM
> > > To: Drummond Reed
> > > Cc: Giovanni Bartolomeo; barnhill_william@bah.com; xdi@lists.oasis-
> > open.org
> > > Subject: [xdi] Re: XDI subjects (was Groups - XDI RDF v8 Comments-
> > Barnhill)
> > >
> > >
> > >
> > >
> > >
> > > One aspect that seems strange with using literals as subjects is that
> > you
> > > can't modify them with XDI messages (I think).
> > >
> > > If you have
> > >
> > > =drummond
> > > +name
> > > "Drummond"
> > >
> > > You can modify the literal like this:
> > >
> > > =drummond
> > > $mod
> > > /
> > > =drummond
> > > +name
> > > "D.Reed"
> > >
> > > But you can't modify a subject.
> > >
> > > What again was a use case for literals in subjects? (I'm not against
> > it,
> > > just asking)
> > >
> > > Markus
> > >
> > >
> > > On Mon, Mar 17, 2008 at 7:34 PM, Drummond Reed
> > <drummond.reed@cordance.net>
> > > wrote:
> > >
> > >
> > >
> > > [renaming this thread to something more relevant]
> > >
> > >
> > >
> > > Giovanni,
> > >
> > >
> > >
> > > I agree with Markus - I can't make sense of having an XDI document as
> an
> > XDI
> > > subject. I'm not sure my point from my earlier message came across,
> but
> > I
> > > was saying that when you use XDI context syntax - the // syntax - it
> > does
> > > _not_ assert that the previous XDI document is the subject of an XDI
> > > statement. It says that the previous XDI statement _contains_ another
> > XDI
> > > statement. For example, in the following X3 Simple graph.
> > >
> > >
> > >
> > > =drummond
> > >
> > > +email
> > >
> > > /
> > >
> > > =drummond
> > >
> > > +email+home
> > >
> > >
> > > "dsr.example@gmail.com"
> > >
> > > +email+work
> > >
> > >
> > > "drummond.example@cordance.net"
> > >
> > >
> > >
> > > .you can make the following "compound XDI statement":
> > >
> > >
> > >
> > > =drummond/+email//=drummond/+email+home
> > >
> > >
> > >
> > > This compound statement does not assert an XDI document as a subject.
> It
> > > asserts the following:
> > >
> > >
> > >
> > > 1) =drummond is an XDI subject
> > >
> > > 2) +email is an XDI predicate of this subject
> > >
> > > 3) The object is another XDI document
> > >
> > > 4) =drummond is an XDI subject in this contained XDI document
> > >
> > > 5) +email+home is an XDI predicate of that XDI subject
> > >
> > > 6) "dsr.example@gmail.com" is the literal value of that XDI object
> > >
> > >
> > >
> > > If you wanted to have an entire XDI document as the subject of an XDI
> > > statement, I think the syntax you are looking for is:
> > >
> > >
> > >
> > >
> > > (xdi-subject/$context$xdi)/xdi-predicate/xdi-object
> > >
> > >
> > >
> > > In this XDI statement:
> > >
> > >
> > >
> > > 1) (xdi-subject/$context$xdi) is a cross reference that uniquely
> > identifies
> > > an XDI document:
> > >
> > > a) xdi-subject is the XDI subject authoritative for a
> > reference
> > > to the XDI document
> > >
> > > b) $context$xdi is the context type
> > >
> > > 2) xdi-predicate is the XDI predicate whose subject is the entire
> > previous
> > > cross-reference
> > >
> > > 3) xdi-object is whatever the XDI object is (literal, another XDI
> > subject,
> > > or another XDI document)
> > >
> > >
> > >
> > > ****************
> > >
> > >
> > >
> > > As for the issue of whether a literal can be an XDI subject, my
> primary
> > > concern about that is how to treat it under XDI addressing rules. In
> > every
> > > XDI context, the XRIs must be unique. So there are two directions we
> > could
> > > take:
> > >
> > >
> > >
> > > 1) Allow literals to be XDI subjects, but ignore them from an XDI
> > addressing
> > > perspective (i.e., they would be "invisible" from an addressing
> > standpoint.)
> > >
> > >
> > >
> > > 2) Allow literals as XDI subjects in syntax, but for addressing
> > purposes,
> > > have a specified transformation into relative XRI. For example:
> > >
> > >
> > >
> > > ["Drummond Reed"[+email[""dsr.example@gmail.com"]]] <==X3 with
> literal
> > as
> > > non-addressable subject
> > >
> > > [%44rummond%20%52eed[+email[""dsr.example@gmail.com"]]] <==X3 with
> > literal
> > > as addressable XRI subject
> > >
> > >
> > >
> > > Thoughts?
> > >
> > >
> > >
> > > =Drummond
> > >
> > >
> > >
> > >
> > >
> > >
> > > ________________________________
> > >
> > >
> > > From: markus.sabadello@gmail.com [mailto:markus.sabadello@gmail.com]
> On
> > > Behalf Of Markus Sabadello
> > > Sent: Monday, March 17, 2008 9:10 AM
> > > To: Giovanni Bartolomeo
> > > Cc: Drummond Reed; barnhill_william@bah.com; xdi@lists.oasis-open.org
> > > Subject: Re: [xdi] Groups - XDI RDF v8 Comments-Barnhill (pdf) (XDI
> RDF
> > v8
> > > Comments-Barnhill.pdf) uploaded
> > >
> > >
> > >
> > >
> > > From the standpoint of having already implemented this, the proposal
> of
> > > allowing a subject to be an XDI document (aka subcontext aka inner
> > graph) is
> > > a nightmare..
> > >
> > > I can think of at least the following immediate problems:
> > > - Some of the serialization formats may not be able to express this.
> > > - We always said that subjects in a graph must be unique. Can this
> > still be
> > > enforced with inner graphs as subjects?
> > > - What will XDI messages look like that make changes to these
> subjects?
> > >
> > > I don't feel too secure about allowing literals as subjects either,
> but
> > I
> > > can't really argue why at this point..
> > >
> > > But I'm just thinking loud.. Of course all this is not necessarily a
> > reason
> > > not to do it :)
> > >
> > > Markus
> > >
> > >
> > > On Sat, Mar 15, 2008 at 1:39 PM, Giovanni Bartolomeo
> > > <giovanni.bartolomeo@uniroma2.it> wrote:
> > >
> > >
> > >
> > > At 20.52 13/03/2008, Drummond Reed wrote:
> > >
> > > Giovanni,
> > >
> > > It's a subtle point, but when you use subcontext syntax (//), the
> > parent
> > > XDI document is not the subject of the child XDI document. It is the
> > > container ("context") for the child. Thus I don't think the ABNF
> should
> > > change.
> > >
> > >
> > >
> > >
> > > Ok, I see; so if my understanding is correct, we have both the
> > possibility
> > > to have a whole XDI document as an RDF object as well as a "contained"
> > > object ("subcontext"). Thus, the original question: in these ABNF
> > excerpts,
> > > how could we specify that a subject can be an XDI document? E.g.
> > >
> > >
> > >
> > > X3 = *( "[" sub *( "[" pred *( "[" obj "]" ) "]" ) "]" )
> > > sub = [ comment ] xri-reference [ comment ]
> > > sub = [ comment ] (xri-reference / X3) [ comment ]
> > > pred = [ comment ] xri [ comment ]
> > > obj = [ comment ] ( xri-reference / literal / X3 ) [ comment ]
> > > literal = """ *char """
> > > comment = "<--" *c-char "-->"
> > >
> > >
> > >
> > > RE the question of whether to allow a literal as an XDI subject, yes,
> I
> > have
> > > thought about, for reasons which I'll explain on today's call (if we
> > have
> > > time).
> > >
> > >
> > >
> > > I would allow this; especially if we'll standardize inverse
> predicates,
> > we
> > > should allow a subject to be a literal, as well as a XDI document or a
> > > xri-reference.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > RE whether a predicate should be able to be an XDI document, my
> > immediate
> > > answer is no - RDF predicates are strictly URIs; XDI predicates should
> > be
> > > strictly XRIs.
> > >
> > >
> > >
> > > Yes, I agree with this. To summarize, I would be in favour of having
> the
> > > same definition for subjects and objects:
> > >
> > > sub = [ comment ] (xri-reference / literal / X3) [ comment ]
> > >
> > >
> > > pred = [ comment ] xri [ comment ]
> > > obj = [ comment ] ( xri-reference / literal / X3 ) [ comment ]
> > >
> > > what do you think?
> > >
> > > Thanks,
> > > Giovanni
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Talk to you shortly,
> > >
> > > =Drummond
> > >
> > > ________________________________
> > >
> > >
> > > From: Giovanni Bartolomeo [
> > > mailto:giovanni.bartolomeo@uniroma2.it]
> > > Sent: Thursday, March 13, 2008 3:11 AM
> > > To: Drummond Reed; 'Markus Sabadello'
> > > Cc: barnhill_william@bah.com; xdi@lists.oasis-open.org
> > > Subject: RE: [xdi] Groups - XDI RDF v8 Comments-Barnhill (pdf) (XDI
> RDF
> > v8
> > > Comments-Barnhill.pdf) uploaded
> > >
> > > Hello Drummond,
> > >
> > > Thanks for this clarification; however, if my understanding is
> correct,
> > > this means that an XDI document can also be subject of another XDI
> > document,
> > > other than object.
> > > Doesn't this implies that we should update ABNF syntax making the
> > > definition of subject somehow similar to the one for object?
> > >
> > > X3 = *( "[" sub *( "[" pred *( "[" obj "]" ) "]" ) "]" )
> > > sub = [ comment ] xri-reference [ comment ]
> > > sub = [ comment ] (xri-reference / X3) [ comment ]
> > > pred = [ comment ] xri [ comment ]
> > > obj = [ comment ] ( xri-reference / literal / X3 ) [ comment ]
> > > literal = """ *char """
> > > comment = "<--" *c-char "-->"
> > >
> > > Further questions are:
> > >
> > > should allow literals as a subject?
> > > should be predicate definition similar to subject and object
> > one
> > > update, e.g. may a predicate contain an XDI document?
> > >
> > > however I'm not quite convinced with these last two ideas... comments
> > > welcome!
> > >
> > > Giovanni
> > >
> > >
> > > At 22.38 12/03/2008, Drummond Reed wrote:
> > >
> > > Just to be clear, the "n-segment" syntax was deprecated in the V9 XDI
> > RDF
> > > Model document (
> > > http://wiki.oasis-open.org/xdi/XdiRdfModel) due to the
> > > problems identified in this thread. To be precise, it was unclear
> > whether
> > >
> > > s1
> > > p1
> > > o1
> > > p2
> > > o2
> > >
> > > meant that s1/p1/o1 was the subject of p2/o2 or not. It was also
> > unclear
> > > how cross-reference syntax would be applied.
> > >
> > > We solved both problems by eliminating "n-segment" syntax in the V9
> > > document. Now it should be unambiguous that if you want to express
> that
> > > s1/p1/o1 is the subject of p2/o2, you say:
> > >
> > > (s1/p1/o1)/p2/o2
> > >
> > > What did remain is the // syntax for subcontexts, which allows you to
> > solve
> > > the RDF "blank node problem" by providing an address for a blank node.
> > That
> > > address is simply // (which fits very nicely from a conceptual
> > standpoint
> > > since the identifier for that segment is "blank").
> > >
> > > So if I want to say that the object of s1/p1 is a blank node, I can
> > write
> > > it as s1/p1// . This creates a new XDI context in which I can express
> > > another set of XDI statements whose XRIs are unique in this context.
> > >
> > > We'll go over the practical uses for this on the call tomorrow -
> agenda
> > > coming out shortly.
> > >
> > > =Drummond
> > >
> > > ________________________________
> > >
> > >
> > > From: markus.sabadello@gmail.com [
> > > mailto:markus.sabadello@gmail.com] On Behalf Of Markus
> > > Sabadello
> > > Sent: Wednesday, March 12, 2008 10:44 AM
> > > To: Giovanni Bartolomeo
> > > Cc: barnhill_william@bah.com; xdi@lists.oasis-open.org
> > > Subject: Re: [xdi] Groups - XDI RDF v8 Comments-Barnhill (pdf) (XDI
> RDF
> > v8
> > > Comments-Barnhill.pdf) uploaded
> > >
> > >
> > > To be honest, I don't really understand the N-Segment syntax anyway.
> > >
> > > Why is
> > >
> > > s1
> > > p1
> > > o1
> > > p2
> > > o2
> > >
> > > better than
> > >
> > > s1
> > > p1
> > > o1
> > > o1
> > > p2
> > > o2
> > >
> > > ?
> > >
> > > Markus
> > > On Tue, Mar 11, 2008 at 4:29 PM, Giovanni Bartolomeo <
> > > giovanni.bartolomeo@uniroma2.it> wrote:
> > > Dear Bill, All,
> > >
> > > reading your comments about XDI RDF v8 (
> > > http://www.oasis-
> > open.org/committees/download.php/27112/XDI%20RDF%20v8%20Comments-
> > Barnhill.pdf
> > > ) I've found this sentence:
> > >
> > > One problem with the 3-Segment syntax is that the N-Segment syntax
> uses
> > > cross-references for
> > > reification. This means 3-Segment syntax has to have a different
> > notation
> > > for a subject which is the
> > > statement itself rather than the object of the statement. The 3-
> Segment
> > > notation for this is a crossreference
> > > within a cross-reference: (()). So a subject of (s/p/o) asserts s/p/o
> > and
> > > starts a new statement
> > > whose subject is o, while a subject of ((s/p/o)) asserts s/p/o and
> > starts a
> > > new statement whose subject is
> > > the statement s/p/o. For example to say that =Drummond is author of
> the
> > > statement =Bill.Barnhill is a
> > > contributor to the resource represented by @example we would use the
> > XRI:
> > > ((@example/+dc+contributor/=Bill.Barnhill))/+dc+author/=Drummond.
> > >
> > > Well, I'm wondering how N3 syntax (and consequently X3 simple)
> > addresses
> > > this problem:
> > >
> > > If my understanding is correct, the N3 syntaxt
> > > <s1> <p1> <o1>
> > > <o1> <p2> <o2>
> > > is equivalent to X3 simple
> > > s1
> > > p1
> > > o1
> > > p2
> > > o2
> > > what if I want to express that the whole statement <s1> <p1> <o1> is
> > the
> > > subject of <p2> <o2>? How this can be represented with X3 Simple?
> > > Breaking into a new subcontext doesn't seem to help, as this
> explicitly
> > > introduce a new subject!
> > > s1
> > > p1
> > > /
> > > s2
> > > p2
> > > o2
> > >
> > > Whereas I just want that the whole statement (s1/p1/o1) is the
> subject
> > of
> > > p2!
> > >
> > > What do you think? Am I missing something?
> > >
> > > Thanks,
> > > Giovanni
> > >
> > >
> > > At 11.06 07/02/2008, barnhill_william@bah.com wrote:
> > >
> > > The document named XDI RDF v8 Comments-Barnhill (pdf) (XDI RDF v8
> > > Comments-Barnhill.pdf) has been submitted by Mr. William Barnhill to
> the
> > > OASIS XRI Data Interchange (XDI) TC document repository. Document
> > > Description: View Document Details:
> > > http://www.oasis-
> > open.org/apps/org/workgroup/xdi/document.php?document_id=27112
> > > Download Document:
> > > http://www.oasis-
> >
> open.org/apps/org/workgroup/xdi/download.php/27112/XDI%20RDF%20v8%20Commen
> > ts-Barnhill.pdf
> > > PLEASE NOTE: If the above links do not work for you, your email
> > application
> > > may be breaking the link into two pieces. You may be able to copy and
> > paste
> > > the entire link address into the address field of your web browser. -
> > OASIS
> > > Open Administration No virus found in this incoming message.
> > > Checked by AVG Free Edition.
> > > Version: 7.5.516 / Virus Database: 269.19.19/1256 - Release Date:
> > > 02/02/2008 13.50
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
>
>
> ---------------------------------------------------------------------
> To unsubscribe from this mail list, you must leave the OASIS TC that
> generates this mail. You may a link to this group and all your TCs in
> OASIS
> at:
> https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]