[Nml-wg] Simple example #1

[Freek Dijkstra]

On 11-07-2012 15:38, Roman Łapacz wrote:
> W dniu 2012-07-11 15:26, Freek Dijkstra pisze:
>> On 11-07-2012 15:16, Roman Łapacz wrote:
>>>      <!-- COMMENT
>>> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>>> -->
>>>      <!-- I propose to use new Relation="representedBy"  -->
>>>      <!--- when an object (in this case a Link can be represented by
>>> an other. Definition of them is the same! -->
>>>
>>>      <nml:BidirectionalLink
>>> id="urn:ogf:network:domainy.net:2012:domainx-domainy-domainx">
>>>        <nml:Relation
>>> type"http://schemas.ogf.org/nml/2012/07/relation/representedBy">
>>>          <nml:Link
>>> id="urn:ogf:network:domainx.net:2012:domainx-domainy-domainx">
>>>        <nml:Relation>
>>>      </nml:Link>
>> I'm not (yet) sure what you mean with this definition. Can you elaborate
>> a bit?
>>
>> My first thought was that you meant an identity relation, like
>> 'isAlias', but since these are two different objects, I guess it's
>> something different. To me, a BidirectionalLink is just a grouping of
>> two Links, with the (implicit) "hasLink" relation.
>>
>> Perhaps a short example in words my help me understand.
> 
> The question is which domain name should be included in the URN of an
> inter-domain link. In this case domain x or domain y. One could say that
> one of those two (that's fine and I remember a discussion about this
> problem in the OGF meeting). But we could also create two bidirectional
> links and one of them is just an an alias (the best name but I wasn't
> sure if I can use it as I'm not 100% sure of the definition of isAlias
> used in the NSI example).

Ah, sorry I got confused because in the XML your relation was

BidirectionalLink --(representedBy)--> Link
instead of
BidirectionalLink --(representedBy)--> BidirectionalLink

It is now clear to me. I indeed think this is the same as an 'isAlias'
relation. I don't have a solid definition at hand, but indeed it should
be some sort of identity relation, which can be used for two different
purposes:

* The above: joining two identifiers given out by different
organisations if they -for whatever reason- can not agree on a common
identifier.

* To add a level of indirection so that a more abstract identifier can
be used externally while a more concrete identifier is used internally.
E.g. the abstract "link-domainx-domainy" isAlias of the concrete
"link-domainx-device-Ahc34-intf3.1-to-domainy-device-Bfg5-intf0.28"

I'm not sure if we should use the "isAlias" relation for both purposes,
but for now I don't see why not.

Freek

(PS: Sorry that my mail client is also messing up the example with it's
wrapping. I recently moved back to Thunderbird, and came to the
conclusion that all mail clients still suck. Offlist suggestions are
appreciated.)