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Subject: Re: [xdi] XDI graph as XRIs
[..] Post is long so won't reproduce it here, but I strongly urge a read for anyone interested in this issue. To me the arguments in that post, and those made on the list here, put me firmly on the side of allowing literals as subjects.
But it poses a further question: How do we represent them? Do we allow 24 and "xx" as literals or only "24" and "xx"? Furthermore if all subjects are XRIs (and I think they should be), how is a literal an XRI?
What is a literal? It could be viewed as a name in the namespace context of it's type. So if we pick one of the following we can treat all literals as XRIs:
a. There is an open class of dollar words that start with $" and end with ", e.g. $"24", $"foo" that represent untyped literals, and you represent a typed literal via either $xsd.int*$"24" or $"24"/$isa/$xsd.int
b. The class of literals is a special class of xrefs that begin with a quote after the opening paren and end with a quot before the closing paren. This has the benefit of making all literals relative to context, but detriment of making typing require $isa.
"cat"@en //the literal "cat" has a counterpart in the English language which points to a real world entity (an animal) "42"^^xsd:integer //the literal "42" is a integer number! "abc"^^dt:specialDatatype //"abc" is a special datatypeso it seems that their use of "literals" is a bit more evolved that simply storing a value.
These are two different topics:
1) Addressing - This is quite clear. Everything in the XDI graph has an XRI address. Since a predicate can not have more than one literal, it is sufficient to have the subject and predicate in the XRI address, e.g. =markus/+email.
2) Storing the whole graph data (including literals) as a set of XRIs - Bill says this is possible. And this is what my question (and I think Nat's too) was about.
Markus
On Sun, May 18, 2008 at 10:50 PM, Drummond Reed < drummond.reed@cordance.net> wrote:
- Markus,
- This subject has indeed come up several times before. I know Bill has suggested that, when looked at from an RDF graph standpoint, every XDI document can be represented as the set of RDF statements that appear in the document. This would include all those whose object is a literal.
- However when we refer to "the set of XRIs" represented by an XDI RDF document, I have proposed that if the object of an XDI RDF statement is a literal, the literal is NOT part of the XRI. In other words, if you have the XDI RDF statement$B!D(B
- =markus
- " markus.sabadello@gmail.com"
- $B!D(Bthe XRI that identifies the literal object of this statement (using direct concatenation syntax) is:
- =markus/+email
- That's as far as we've gone discussing it.
- Is there any reason that rule will not work?
- =Drummond
- From: Markus Sabadello [ mailto:markus.sabadello@gmail.com]
- Sent: Friday, May 16, 2008 6:12 PM
- To: Bill Barnhill
- Cc: Nat Sakimura; tatsuki@nri.com; xdi@lists.oasis-open.org
- Subject: [xdi] XDI graph as XRIs
- Hey Bill,
- I'm sitting together with Nat and Tatsuki, talking about various XDI topics. One issue that came up was the following: I think it was you who suggested a few times that every XDI document can be expressed as a simple list of XRIs, right?
- For example, if I have this XDI graph:
- =markus
- +friend
- =bill.barnhill
- =drummond
- I could just express it using these XRIs:
- =markus/+friend/=bill.barnhill
- =markus/+friend/=drummond
- Right?
- Now the question is, how does that work with literals? If I have this:
- =markus
- " markus.sabadello@gmail.com"
- Then what's the XRI that represents this statement? I'm sure someone has thought about that before, but I don't really remember how it works or if it works at all?
- Markus
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