Using URI strings as identifiers

["G. Ken Holman" <gkholman@CraneSoftwrights.com>]

Hello again,

This is related to my previous post an hour ago about URIs for namespaces:

   http://lists.oasis-open.org/archives/ubl/200503/msg00047.html

... but in this post I'm not talking about namespaces or schemas, I'm 
talking about unique identifiers.

SBSC is contemplating the need to use URI strings as unambiguous, globally 
unique, identifiers for resources.  This is consistent with IETF RFC 2396 
for URI: "A Uniform Resource Identifier (URI) is a compact string of 
characters    for identifying an abstract or physical resource."

These resources will have their own versions as they evolve.  According to 
NDR 3.5 "UBL has decided to include versioning information as part of the 
document-id component of the namespace." ... this would imply to me that we 
would do the versioning solely in the URI of the identifier, rather than 
introduce a version attribute.

We would capture the identification of the set of XPath expressions for a 
subset by using an id= attribute with the URI string as an identifier for 
the expression itself, of which document model it is a subset, and at which 
version.

So we could have the following:

   <xpath xmlns="urn:oasis:names:specification:ubl:schema:relax-ng:XPath-1.0"
          id="urn:oasis:names:specification:ubl:xpath:Invoice-1.0:1.0">
     <element name="Invoice" type="InvoiceType" prefix="in"
              uri="urn:oasis:names:specification:ubl:schema:xsd:Invoice-1.0"
              minOccurs="1" maxOccurs="1">
       ...

In the above id= attribute I'm identifying this set of XPath information as:

   "urn:oasis:names:specification" - an OASIS specification
   "ubl" - for the UBL project
   "xpath" - for an expression of qualifying XPath addresses
   "Invoice-1.0" - for the UBL 1.0 Invoice
   "1.0" - version 1.0 of the XPath expression

Perhaps we need "sbsc" or "SBS" in there somewhere?

If you have any comments on the default namespace used above to identify 
the vocabulary expressing the XPath information, please see the cited 
message at the top of this message.

In this thread, please share any thoughts you have on guiding our 
subcommittee in the creation of these unique resource identifying URI strings.

..................... Ken

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