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Subject: RE: [xdi] Groups - Comments about XDI versioning (Draft-Contrib-OASIS-XDI-versioning.pdf) uploaded

Reassignability is a convention that applies only at the XRI namespace level.


For example, an XRI namespace registry might do this:

  1. Mint a new XRI authority (record) for a paying customer.
  2. Assign it a local (bang) inumber to be returned as the final subsegment of it’s CID.


If the given XRI namespace registry is well-behaved, then it will follow the convention that it will not re-use the authority with the local inumber for another customer. (It won’t re-assign it to another customer.)


So, in this case, this notion of “not re-assigning” is a convention to be followed by well-behaved XRI namespace registries.



So what about the name space “$” and the child “1”. It would probably be a good convention that if “$” assigned the child authority named “1” to the concept of the integer value 1 then it shouldn’t at some later date assign  the local identifier to some other concept (like the real number pi, for example.)




In summary, the convention that “$” is not going to reassign the local identifier “1” to “the concept of the real number pi” has nothing to do with assigning markus assigning the identifier =markus$v!1 to a mutable collection.


~ Steve




From: markus.sabadello@gmail.com [mailto:markus.sabadello@gmail.com] On Behalf Of Markus Sabadello
Sent: Friday, February 22, 2008 8:11 AM
To: Barnhill, William [USA]
Cc: giovanni.bartolomeo@uniroma2.it; xdi@lists.oasis-open.org
Subject: Re: [xdi] Groups - Comments about XDI versioning (Draft-Contrib-OASIS-XDI-versioning.pdf) uploaded


Hmm yes right, ! is persistent, so it doesn't work for mutable collections, I didn't think about that. If I have 5 e-mail addresses, one of them may get deleted. But in versioning persistence is what you want (version 2 will never change or go away..). So maybe the solution is to support both ! and *.

Versioning example (persistent):

=markus/$has!5/$v   <-- in the metagraph model, $has is for composite subjects, right? -->

Multiple e-mails example (reassignable):

=markus/$has$a*5/+email  <-- in the metagraph model, $has$a is for predicates, right? -->

Anyway, just a thought. It would be great if somehow the same mechanism could be used for "I have 5 versions" and "I have 5 e-mail addresses".

How would the +yesterday construct work? Would the endpoint look at timestamps on the individual version snapshots and find out which one to return?


On Fri, Feb 22, 2008 at 10:04 AM, Barnhill, William [USA] <barnhill_william@bah.com> wrote:


Hi guys,

You both have some very good and interesting points. Just saw this though and wanted to send off a thought: while ! syntax is easier to understand and read imho, it also might lead to a problem. If you are using it to things in a modifiable collection your collection order could change, or you could insert someplace other than the tail of the collection. This would mean you would need to reassign your ! identifiers, but are they reassignable? $n would get around that and lower the verbosity closer to ! level.

For versioning, I like best the following:

=drummond/$has/$v   (this says that =drummond is versioned)
=drummond/$v/5   (this says the current version is 5)


I think $v should by default be a # in the dictionary. If you want to access yesterday's last version you can do
which accesses statements of the form

What do you think?,

-----Original Message-----
From: markus.sabadello@gmail.com on behalf of Markus Sabadello
Sent: Thu 2/21/2008 10:45 PM
To: giovanni.bartolomeo@uniroma2.it
Cc: xdi@lists.oasis-open.org
Subject: Re: [xdi] Groups - Comments about XDI versioning (Draft-Contrib-OASIS-XDI-versioning.pdf) uploaded

Heya Giovanni,

Since I already tried to implement the versioning described in the XDI RDF Model v8 doc, it's interesting for me to read your comments about this..

- Regarding the use of $num instead of ! to index things, I think it's mostly a matter of taste. Both would work fine I think. One thought I am having is that subsegments like !1, !2, !3 do exist in XRI resolution too. I.e. there are some authority resolution servers that use these number-like subsegments (and not ip address-like subsegments like !203.173.1276.1663)..

- Regarding the number of versions, can I ask you something?

Maybe you can take a quick look at this URL: http://graceland.parityinc.net/xdi-endpoint/hibernate-graph-ver/=drummond
As you can see there are the following two statements:

=drummond/$has/$v   (this says that =drummond is versioned)
=drummond/$v/!5   (this says the current version is 5)

I'd like to understand how you would do it instead.

Would you say this?

Or this?

Just trying to understand it correctly.. I like the idea very much, it makes versioning a bit simpler and more consistent with other constructs..

Note to Drummond: We were talking about how to express multiple values of an attribute (e.g. =markus has multiple +email addresses). After reading Giovanni's comments, it appears to me that versioning may just be another instance of that same problem. I.e. there's no difference between saying =markus has 5 +email addresses, and saying that =drummond has 5 $v ersions. I agree with Giovanni that the same construct should be used in both cases.

- I don't understand why I would use the comparison operators like $greater in versioning.. What would be a practical use case for this? But in general I think these operators can be very useful..


On 14 Feb 2008 13:53:29 -0000, <giovanni.bartolomeo@uniroma2.it> wrote:

The document named Comments about  XDI versioning
(Draft-Contrib-OASIS-XDI-versioning.pdf) has been submitted by Giovanni
Bartolomeo to the OASIS XRI Data Interchange (XDI) TC document repository.

Document Description:
A first draft of comments on XDI versioning syntax

View Document Details:

Download Document:

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may be breaking the link into two pieces.  You may be able to copy and paste
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