[Nml-wg] hasPort/hasLink vs providesPort/providesLink

[Aaron Brown]

On Aug 21, 2012, at 10:30 AM, Freek Dijkstra wrote:

> Roman's mail reminded me on the following relation terms.
> 
> hasTopology/hasNode/implementedBy related Topologies and Nodes:
> 
>   Topology X --hasTopology--> Topology Y
>   Topology Y --hasNode--> Node Z
>   Node Z --implementedBy--> Node W
> 
> Question 1: implementedBy seems a bit off here, relating a subset to a
> larger part (while hasTopology and hasNode relate a larger part to a
> subset). Is that OK?
> (Personal opinion: I have never seem an example that used implementedBy,
> so I consider it somewhat experimental and thus don't really care)

Seems reasonable to me. "ImplementedBy" could theoretically involve multiple elements, so putting the 1:M relationship into the '1' side instead of the 'M' side seems fine to me. This is an area where it might be nice to have the reverse relationship available so if you're looking at a member of the 'M' part of the relationship, you could see that it's involved there, but i'm not sure it much matters right now.

> hasPort and hasLink relate Groups with its elements:
> 
>   PortGroup G --hasPort--> Port P1
>   PortGroup G --hasPort--> Port P2
>   PortGroup G --hasPort--> Port P3
>   LinkGroup L --hasLink--> Port L1
>   LinkGroup L --hasLink--> Port L2
>   LinkGroup L --hasLink--> Port L3
> 
> providesPort and providesLink relate Service to it's dynamic configuration:
> 
>   SwitchingService S --providesLink--> Link crossconnect1
>   SwitchingService S --providesLink--> Link crossconnect2
>   SwitchingService S --providesLink--> Link crossconnect3
> 
>   AdaptationService A --providesPort--> Port vlan1
>   AdaptationService A --providesPort--> Port vlan2
>   AdaptationService A --providesPort--> Port vlan3
> 
> Question 2: are the names "hasPort" and "hasLink" well-chosen? (An
> alternative would be containsPort and containsLink).
> (Personal opinion: I think they're OK: they behave similar to hasToplogy
> and hasNode)

I like that they match the other 'has' relations.

> Question 3: Are providesLink and providesPort well-chosen? Could we
> reduce the number of relations by just using hasLink and hasPort instead?
> (I have no personal opinion on this issue)

I guess I'd need to see what the difference would be since I'm not positive how they'd be used in practice.

Cheers,
Aaron

> 
> Freek
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