Hi Freek-

Regarding the "connectedTo" or "mapsTo" terms in the NSI topology, those could be different strings if NML is already using them in a different sense.   We could in NSI use the term "sharesInterfaceWith" or "internallyTranslatesTo" for each of those respectively.   THis ould be a minor change for us.

More important to NSI is that there be the semantics that those relations represent. 

On a slightly different issue -
I saw a comment somewhere (maybe the minutes of THursday's call?) that said NSI was not using the SDP relations...  This is wrong.   NSI very much uses SDPs in the current topology.

SDPs are represented within an STP object with a "connectedTo" relation referencing another STP object.   Here is a OWL snippet:
    <owl:NamedIndividual rdf:about="urn:ogf:network:stp:northernlight.ets:poz-1">
        <rdf:type rdf:resource="http://www.glif.is/working-groups/tech/dtox#STP"/>
        <connectedTo rdf:resource="urn:ogf:network:stp:pionier.ets:cphb"/>
    </owl:NamedIndividual>
In this snippet, NorthernLight STP "poz-1" is in an SDP relationship with the Pionier STP "cphb".   The Snippet is the STP object defined for NothernLight.    A mirror image STP is defined in Pionier.   Thus a path finder traversing the networks in either direction will easily see the SDP relation.

There may be better ways to represent the SDP, this was what we did for the fall...We can discuss others...

The NSI topological representation (i.e. the OWL/RDF form) could take other forms that we currently have as long as the semantics of the three key NSI objects are preserved: NSI Networks (service domains), STPs (edge ports/points), and SDPs (adjacencies).   These are I think represented in NML, though there is probably a different notion of "link" vs "SDP" that we need to reconcile...and maybe some of the mechanics of the "port" vs "STP" ...  These notions are very close.
 
Jerry

On 2/16/12 10:57 AM, Freek Dijkstra wrote: 
A somewhat related issue on source/sink. I don't think this was ever
written down.

Freek Dijkstra wrote:


The question at hand is basically how to describe the following (with
apologies with my poor ASCII art skills)

port A    link X    port B    link Y    port C
  O------------------>O------------------>O


[...]

In the NML schema it is currently defined as:

 link X
    relation=source
        port A
    relation=sink
        port B
 link Y
    relation=source
        port B
    relation=sink
        port C

For the record, an alternative way to describe this is making the ports
leading instead of the links:

 port A
     relation=egress
         link X
 port B
     relation=ingress
         link X
     relation=egress
         link Y
 port C
     relation=ingress
         link Y

Technically I think these are equivalent: the provide a directed
relation between links and ports. Which one is syntactically better
depends what is more common, a one-to-many or a many-to-one relation
between ports and links.

For the circuits, this is often a one-to-one relation.
Since we implemented cross-connects as links, VLANs are likely also
described as some kind of "link", but one with multiple sources and
sinks. Hence, there is a one to many relation from link to port.
This means that the source and sink relation we have now is more easy to
convey in XML than the alternative ingress and egress relation.

I personally think the source/sink stuff is still the best alternative
we have.

Regards,
Freek
_______________________________________________
nml-wg mailing list
nml-wg@ogf.org
https://www.ogf.org/mailman/listinfo/nml-wg