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Subject: RE: [xdi] Resource and Data

Will, I'm totally with you. I strongly favor UML terms myself.


Is the noun you're talking about the potential name for a container for subresources? If so, since subresources represent association objects describing the association of their parent resource with another resource, <association> would seem to be a good choice. Bil Barnill has suggested <assoc> for brevity.


Loren has suggested calling it <meta> since its all metadata describing the association.


Of course, per the earlier messages in this thread, before we discuss what to call it, we need to decide if adding a container element for subresources is the best approach. So far the discussions I've been party to have all agreed that a container for subresources is not strictly necessary – the parent Resource already serves as a container, although of not just the subresources alone (since it also includes the Data branch). But the subresources are all easily addressable as a group using XPath.


I'll try to summarize the arguments as I understand them both for and against a container element for Subresources.



The argument for (which Bill Barnhill will be posting a detailed version of) is that it provides an efficient way in XML to specify the set of subresources that describe the association of a Resource to other Resources.


Another argument for, which both Bill and Loren have made, is that the subresource container element is actually a better way to model the "XDI tuple" since it aggregates all subresources into the "predicate" branch the same way the Data element aggregates all of its contained resources (if any) into one branch. So the tuple really becomes "Resource, Association, Data" with XRIs serving to identify a Resource in all 3 legs.



The argument against is that the XML serialization of the XDI metamodel itself already provides a container (the parent Resource) and that adding another container just to turn the subresources into their own branch only adds XML processing overhead.


Another argument against is that the XDI tuple is already represented by Resource, XRI, Data, and that adding another element only adds processing overhead that will add up in very large XDI data stores (imagine XML databases containing billions of XDI documents.)



Whew! This is going to be a tough one.




From: Will St Germain IV [mailto:willstg@us.ibm.com]
Sent: Wednesday, August 18, 2004 3:34 PM
To: Drummond Reed
Cc: 'Loren West'; xdi@lists.oasis-open.org
Subject: RE: [xdi] Resource and Data



The more we learn UML as a language to communicate, it seems reasonable to align to the same nouns when we talk about moving data from one persistence to another?  (note, as an observer I may be totally out of touch with the topic:)

The nouns that come to mind are:

Reference:  http://www.omg.org/technology/documents/formal/uml.htm


Will St. Germain IV
Senior Transition and Information Architect,

"Drummond Reed" <drummond.reed@cordance.net>

08/18/2004 03:59 PM


"'Loren West'" <loren.west@epok.net>, <xdi@lists.oasis-open.org>




RE: [xdi] Resource and Data




Both Loren and Bill have brought up the potential need for a container
element for subresources (Resources contained by a parent Resource in the v5
metaschema). Both of them have good arguments for it, and I've shared with
them at least one good argument against it.

The net net is that it's a wonderful, meaty topic that we'll be diving into
on today's call.


-----Original Message-----
From: Loren West [mailto:loren.west@epok.net]
Sent: Wednesday, August 18, 2004 2:46 PM
To: xdi@lists.oasis-open.org
Subject: RE: [xdi] Resource and Data

Funny.  I read Gabe's request to mean the difference between <data>
and it's sibling <resource> elements.  Drummond read the request
as the difference between <data> and it's parent <resource>.

Now I'm more convinced than ever that we need a different name
for the <resource> elements that are siblings to <data> (or
at least group them under a <meta> tag).  They often times
get confused with the parent <resource> element.


-----Original Message-----
From: Drummond Reed [mailto:drummond.reed@cordance.net]
Sent: Wednesday, August 18, 2004 2:34 PM
To: 'Wachob, Gabe'; xdi@lists.oasis-open.org
Subject: [xdi] Resource and Data

Gabe, it's a fine question. We've been working with the Resource/XRI/Data
element names for long enough now that no one has bothered to ask this basic

I will give a very precise definition according to RFC2396bis and XRI 1.0.
An XDI "resource" is an entity that can be represented in an XDI document
and identified by an XRI. Period. It's abstract in the extreme.

XDI "data", by contrast, is any information that can be represented in an
XDI document that IS NOT identifiable by itself, but must be placed in the
context of one or more XRIs in order to become identifiable.



The value "43" in this XML element is XPath-addressable (in the scope of a
specific XML document) but not XRI-addressable.


Now this data has become identifiable - in both a local and global context -
with an XRI and thus now meets the RFC2396bis and XRI 1.0 definition of a

Of course, data does not have to be just a literal value. Complex data can
be a collection of resources. However, a collection of resources (each of
which itself is identifiable) needs to be put in the context of one or more
XRIs to be identifiable as a *collection*, so it still meets the definition
of data.

The next step beyond this simplest definition is to compare the XDI tuple
with the RDF tuple, and talk about Resource as Subject, XRI as Predicate,
and Data as Object. That was addressed in the powerpoint uploaded for the
last TC call

With your knowledge of RDF, I would love your feedback on that view of
Resource and Data.


-----Original Message-----
From: Wachob, Gabe [mailto:gwachob@visa.com]
Sent: Wednesday, August 18, 2004 11:27 AM
To: drummond.reed@cordance.net; xdi@lists.oasis-open.org
Subject: RE: [xdi] Groups - draft-xdi-metaschema-v5.xsd uploaded

                Can you explain in a sentence or two what the meaning of resource
vs. data is? This doesn't seem to be documented anywhere - you may have
discussed this on the phone calls, but I don't see explanation in the
minutes (not that I'd expect such content to be in minutes).



Chief Systems Architect
Technology Strategies and Standards
Visa International
Phone: +1.650.432.3696   Fax: +1.650.554.6817

> -----Original Message-----
> From: drummond.reed@cordance.net [mailto:drummond.reed@cordance.net]
> Sent: Tuesday, August 17, 2004 11:39 PM
> To: xdi@lists.oasis-open.org
> Subject: [xdi] Groups - draft-xdi-metaschema-v5.xsd uploaded
> The document draft-xdi-metaschema-v5.xsd has been submitted
> by Drummond Reed (drummond.reed@cordance.net) to the OASIS
> XRI Data Interchange (XDI) TC document repository.
> Document Description:
> v5 Proposed XDI Metaschema (only change is Comment element eliminated)
> Download Document:  
> http://www.oasis-open.org/apps/org/workgroup/xdi/download.php/
> 8761/draft-xdi-metaschema-v5.xsd
> View Document Details:
> http://www.oasis-open.org/apps/org/workgroup/xdi/document.php?
> document_id=8761
> 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.

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