[Nml-wg] NML-NSI integration

[Roman Łapacz]

W dniu 2012-02-17 16:28, Freek Dijkstra pisze:
> Hi all,
>
> A port can have many properties. It can be abstract, Ethernet, (NSI)
> domain boundary port, have restricted access, be part of a link bundle.
>
> What I want to avoid is having to deal with namespaces and objects such
> as<nml-nsi-ethernet-restricted-lacp:port>
>
>> If we allow adding new tags as extensions in any place in the structure
>> then we don't have too much control over the structure. Generic parsers
>> will not know how to interpret such unexpected (not included in the base
>> NML schema) changes. On the contrary, namespaces as extensions allow
>> parsers to, at least, understand their standard properties, others would
>> be ignored. The structures defined in the base NML schema are still
>> followed. (Of course it is possible to define a schema in such way that
>> any element could be inserted in any place but I don't think it's the
>> right direction).
> The RNC schema you created last year DID allow arbitrary elements inside
> NML elements.
>
> I think I misunderstand you. In particular, I do not understand the
> sentence "namespaces as extensions allow parsers to, at least,
> understand their standard properties."
>

a very simple example

<nml-ext:x>
<nml:y></nml:y>
<nml-ext:z></nml-ext:z>
</nml-ext:x>

A parser which does not understand the nml-ext extension/namespace would 
treat x as nml:x (of course if nml:x exsits) and ignore nml-ext:z.


Roman


> Are you talking about chameleon namespaces?
>
> I assume that:
>
> * NML elements can contain arbitrary child elements, from the NML or
> other namespace
> * if a parser encounters an unknown element from a known namespace, it
> should stop and return an error
> * if a parser encounters an element from a unknown namespace, it should
> ignore it (or -if we define chameleon namespaces- interpret as if it was
> part of the base namespace)
> (Note that in this case, I'm unclear how a parser should distinguish
> between a chameleon namespace and a proprietary namespace which can
> safely be ignored.)
>
> Could you perhaps give an example of a message containing NML and NSI
> information, and explain how a parser which only understands NML sees
> it, and how a parsers understands both NML and NSI sees it, and if
> either should ignore unknown elements or stop and return an error?
>
> Freek
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