[Nml-wg] References

Fri Sep 21 10:42:30 EDT 2012

W dniu 2012-09-21 16:34, Aaron Brown pisze:
>
> On Sep 21, 2012, at 7:08 AM, Jeroen van der Ham wrote:
>
>> Hi,
>>
>> I actually meant it more like the following:
>>
>> <nml:Port id="urn:ogf:network:example.net:2012:port-X:out">
>> <nml:Label 
>> encoding="http://schemas.ogf.org/nml/2012/10/ethernet/vlan">1501</nml:Label>
>> <nml:Relation 
>> type="http://schemas.ogf.org/nml/2012/10/relation/isSource">
>> <nml:Link id="urn:ogf:network:example.net:2012:linkA:XY">
>> <nml:Relation 
>> type="http://schemas.ogf.org/nml/2012/10/relation/isDefinedBy">
>> http://example.com/topology-description.xml
>> </nml:Relation>
>> </nml:Link>
>> </nml:Relation>
>> </Port>
>
> The implication of isDefinedBy here is that all topology is an HTTP 
> GET away. I'm not sure I like encoding "how to get remote topologies" 
> into the base schema defining how we represent topology. As an 
> extension, it might be reasonable, but not in the base.

Agree.

Roman

>
> Cheers,
> Aaron
>
>>
>> Jeroen.
>>
>> On 21 Sep 2012, at 11:42, Roman Łapacz <romradz at man.poznan.pl 
>> <mailto:romradz at man.poznan.pl>> wrote:
>>
>>> I decided to visualize the proposed change using an example:
>>>
>>> IdRef:
>>>
>>> <nml:Port id="urn:ogf:network:example.net:2012:port-X:out">
>>> <nml:Label 
>>> encoding="http://schemas.ogf.org/nml/2012/10/ethernet/vlan">1501</nml:Label>
>>> <nml:Relation 
>>> type="http://schemas.ogf.org/nml/2012/10/relation/isSource">
>>> <nml:Link idRef="urn:ogf:network:example.net:2012:linkA:XY"/>
>>> </nml:Relation>
>>> </Port>
>>>
>>>
>>> transformed to use isDefinedBy (the way how I see it):
>>>
>>> <nml:Port id="urn:ogf:network:example.net:2012:port-X:out">
>>> <nml:Label 
>>> encoding="http://schemas.ogf.org/nml/2012/10/ethernet/vlan">1501</nml:Label>
>>> <nml:Relation 
>>> type="http://schemas.ogf.org/nml/2012/10/relation/isSource">
>>> <nml:Link id="urn:ogf:network:example.net:2012:linkA:XY">
>>> <nml:Relation 
>>> type="http://schemas.ogf.org/nml/2012/10/relation/isDefinedBy">
>>> <nml:NetworkObject 
>>> type="http://schemas.ogf.org/nml/2012/10/type/unknown"/>
>>> </nml:Relation>
>>> </nml:Link>
>>> </nml:Relation>
>>> </Port>
>>>
>>>
>>> I've introduced a new abstract element nml:NetworkObject that is 
>>> useful to indicate that the definition is somewhere but does not 
>>> have to be specified in this xml doc. I don't think we can assume 
>>> that we must know it in advance. For example, definitions may be 
>>> located dynamically in some lookup repositories (perfSONAR services 
>>> does not have to upload their metadata information only to one LS 
>>> service all the time).  Thus definition location may be found by 
>>> some lookup mechanism.
>>>
>>> I'm fine to use Topology inside Relation if this relation is known:
>>>
>>> <nml:Relation 
>>> type="http://schemas.ogf.org/nml/2012/10/relation/isDefinedBy">
>>> <nml:Topology id="urn:ogf:network:gn3.net:2012:org"/>
>>> </nml:Relation>
>>>
>>>
>>>
>>> The use of Relation for referencing may be useful also for name/id 
>>> mapping (an id points another id). I'm not sure this may be useful 
>>> for someone but I can imagine a use case where names of network 
>>> elements are assigned with a project (see below: pionier network 
>>> element used in the GN3 project). Such mapping may be helpful for 
>>> flexible lookup operations.
>>>
>>> <nml:Port id="urn:ogf:network:gn3.net:2012:port-X:out">
>>> <nml:Relation 
>>> type="http://schemas.ogf.org/nml/2012/10/relation/isDefinedBy">
>>> <nml:Port id="urn:ogf:network:pionier.net:2012:port-X:out"/>
>>> </nml:Relation>
>>> </Port>
>>>
>>> <nml:Port id="urn:ogf:network:pionier.net:2012:port-X:out">
>>> <nml:Label 
>>> encoding="http://schemas.ogf.org/nml/2012/10/ethernet/vlan">1501</nml:Label>
>>> <nml:Relation 
>>> type="http://schemas.ogf.org/nml/2012/10/relation/isSource">
>>> <nml:Link idRef="urn:ogf:network:pionier.net:2012:linkA:XY"/>
>>> </nml:Relation>
>>> </Port>
>>>
>>>
>>> Roman
>>>
>>>
>>> W dniu 2012-09-21 09:50, Jerry Sobieski pisze:
>>>> If I understand this correctly, and if I also understand the usage 
>>>> context with regard to "topologies", I vote for the isDefinedBy 
>>>> construct as we will be looking to acquire what is likely to be a 
>>>> substantial amount of topology information that is maintained in a 
>>>> separate document somewhere.
>>>>
>>>> And I would salute the desire to keep multiple representations as 
>>>> similar as possible.
>>>>
>>>> (just letting you know I am following these discussions:-)
>>>> J
>>>> On 9/20/12 8:44 PM, Freek Dijkstra wrote:
>>>>> On 20-09-2012 17:13, Jeroen van der Ham wrote:
>>>>>> Hi,
>>>>>>
>>>>>> We've been discussing references, meaning things that are not defined
>>>>>> locally, but you do want to provide additional information about
>>>>>> them. For XML there has been a proposal to use id / idRef to denote
>>>>>> something like that. Unfortunately it is not very easy to port that
>>>>>> construct to RDF/OWL. The only way to express something like that in
>>>>>> RDF/OWL is by using a relation. Fortunately a relation like that
>>>>>> already exists in the form of rdfs:isDefinedBy. This states that an
>>>>>> object is actually defined by another description, and conveniently
>>>>>> provides the URL of that description to reference it.
>>>>>>
>>>>>> Could we perhaps use the isDefinedBy construct also in XML to make
>>>>>> the reference definition somewhat more explicit? This would really
>>>>>> help keeping the difference between the two syntaxes at a minimum
>>>>>> also.
>>>>> A summary of the earlier discussion:
>>>>>
>>>>> idRef is suppossed to be a shortcut for id + isReference True.
>>>>>
>>>>> isReference is supposed to mean that the object was defined elsewhere,
>>>>> like in another document/by another organisation (there was still a
>>>>> discussion between Aaron and myself if 'elsewhere' may or may not
>>>>> included 'elsewhere in the file --- thinking about it now, I would say
>>>>> 'in another Topology').
>>>>>
>>>>> The distinction between isReference and isDefinedBy is that 
>>>>> isReference
>>>>> only tells the parser that it is defined elsewhere; isDefinedBy also
>>>>> tells the parser where it is defined.
>>>>>
>>>>> I have no preference. Based on Jeroen's proposal and the earlier
>>>>> discussion, what it most useful?
>>>>>
>>>>> Freek
>>>>> _______________________________________________
>>>>> nml-wg mailing list
>>>>> nml-wg at ogf.org <mailto:nml-wg at ogf.org>
>>>>> https://www.ogf.org/mailman/listinfo/nml-wg
>>>>
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>>>
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>>
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>
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