[Nml-wg] Schema changes

[Freek Dijkstra]

>> - Freek: Change the hasPort relation Node-Link to Group-Link and make
>> Node a subclass of Group. This allows a relation between Port and
>> Topology (for describing edge interfaces of a domain, which was not
>> possible with the current schema).

Jeroen van der Ham replied:

> I assume you mean Node-Port and Group-Port there?

Yes, you are absolute right. Thanks for spotting this.

> Why are you proposing to make Node a subclass of Group?
> I don't really see any practical reason for it, other than that it makes 
> it esthetically more pleasing in the UML diagram, by having only one 
> hasPort relationship.

I actually did not think of defining two hasPort relations.

I have no strong preference either way, though defining it once seems
more "clear" to me. It would be odd that in that case it would also
apply to other groups, like Bidirectional link.

Perhaps we should distinguish between group of ports (like node and
topology) and group of transport elements (such as two unidirectional
links that make up a birectional link). Just a thought (I'm not yet in
favour of doing so, as it makes the schema more complex, and don't see a
clear benefit yet).

Regards,
Freek