[Nml-wg] [Nsi-wg] NML Topology identifiers

[Jeroen van der Ham]

Hi,

On 11 Dec 2013, at 11:33, Henrik Thostrup Jensen <htj at nordu.net> wrote:

> On Tue, 10 Dec 2013, Jeroen van der Ham wrote:
> 
>> A problem however is with the way you plan to use the urn:ogf:network identifiers. The use of these identifiers has been defined and standardised, according to the IETF and IANA guidelines. The reason for these restrictions and standardisation are to have persistent, globally unique identifiers, without having to have a central registry of our own.
> 
> AFAICT the way we generate the URNs is perfectly valid. If not, please be specific. In fact, the topology that we will generate should be consumable by any "normal" NML consumer.
> 
>> Changing these identifiers to leave out certain parts because this is more convenient is simply not an option, as it breaks current and future compatibility. You will have to use a different namespace or identification scheme for this.
> 
> Is this just referring to the date part or something else?

Yes, quoting GFD:

> NURN = "urn:ogf:network:" ORGID ":" OPAQUE-PART *1QUERY *1FRAGMENT
> ORGID = FQDN ":" DATE ; ID of assigning organisation
> DATE = YEAR *1(MONTH *1DAY) ; Date of creation of ORGID
> 

> I still have problems wrapping my head around the rationale for these URNs: We put severe restrictions on how to generate them, but they are in no way enforcable. We put a lot of information into the URNs when generating them, but you are not allowed to interpret them. Seriously?

The restrictions have been put in place to make a way of generating them such that they are globally unique without needing an (extra) central registry.

I follow the philosophy of the Semantic Web where identifiers are just that, identifiers. They do not have any intrinsic semantic value. Any semantic value on identifiers should be defined explicitly. Again, this provides an extremely flexible model, where for example you dodge the big problem like the locator / identifier split we have in IP networks (meaning sessions break as you move). This has an adoption cost, but allows for much greater flexibility in the long run.

John has dug up references of use of URNs where it is allowed to analyze the structure of the identifiers and to interpret that.  So it seems that I was mistaken.


Jeroen.