[Nml-wg] id/idRef

[Aaron Brown]

On Jul 12, 2012, at 4:58 AM, Freek Dijkstra wrote:

> Last, a long-time discussion:
> 
> Roman spotted another issue:
> 
>>>> The idRef="urn:ogf:network:nordu.net:2011:NORDUnet:org" does not
>>>> appear to point at anything.
> 
> Freek replied:
> 
>>> Good catch. Frankly, the difference between id and idRef is never
>>> properly defined.
> 
> Roman clarified:
> 
>> The idea of id and idRef was taken from NM/NMC and it's very useful
>> to make distinction between definitions and references to those
>> definitions.
> 
> I am aware of the origin, but will repeat my original rather firm
> statement: I've never seen a proper definition of the difference between
> the two. I've seen vague statements about origin, but I do not think
> that NML should use id/idRef to make statements about origin, if only
> for the reason that RDF does not contain id nor idRef.
> 
> We did try to come up with a proper solution in
> https://forge.ogf.org/sf/go/artf6555
> 
> But that discussion was stranded by some terminology discussion in the
> related https://forge.ogf.org/sf/go/artf6553 (warning: long read)
> 
> We did not get a consensus on the terminology, let alone find a solution
> how to encode it in either XML or RDF.
> 
> I encourage you to come up with a good explanation what you want to
> distinguish between, and how you want to make that distinction -- both
> in XML and in RDF.
> 
> I am looking forward to that proposal, but by lack thereof, I claim that
> we're better of without the id/idRef distinction, since it will only
> lead to confusion.

I don't have a strong opinion on using id/idRef, as the method, but the idea is based around inheritance. As an example, you have port P defined in topology T. When referencing the port in topology S, I might want to override some of its properties (e.g. include our name for its Port). Another example might be the example I sent to the NSI list where I override the VLANs of the PortGroup so that the VLAN is chosen from a subset of the VLANs available.

Using idRef allows an object to say "i'm defining some attributes of this network object. However, I inherit the rest of the attributes for this network object from the network object defined by the id I give in the idRef field".

Cheers,
Aaron

> 
> Freek
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