[Nml-wg] XML Examples and Proposals

[Freek Dijkstra]

All,

Can we agree that we have two use cases:
* A link with a certain reservation (with start and endtime)
* Update of the internal of a topology

And two techniques to represent either:
* Lifetime object with start time and optional end time
* version (sequence number) which can be interpreted as a start time

Looking at the use cases individually, I would say that the most elegant
solution for use case 1 (reservation time) is a lifetime object.
The most elegant solution for use case 2 (updates) is a version sequence
number.

Looking at both use cases, I have a preference to pick one solution,
rather than two solutions.

My initial idea was to pick version sequence number, and get rid of
lifetime.
Jason proposes to keep lifetime, and use it for use cases.
Jeroen proposes to keep both concepts.

Despite my initial preference, I know am inclined to keep both concepts.
The reason is that I can very well envision the following scenario:

telco: "Here is your link reservation, it's from 2 to 4 tomorrow"
user: "thanks, I found out I need it a bit longer, can you extend my
reservation?"
telco: "Sure, here is an update of your reservation. it's now from 2 to
5 tomorrow"
user: "great"

In this scenario, one can attach a version sequence number to a lifetime
object. (let me know if you want the XML version of the above exchange.)

The mere fact that it is possible to logically combine the concepts in a
single message with a perfectly valid meaning got me convinced that
we're dealing with two distinct attributes.

Hence, I changed my opinion, and have a slight preference to keep both
concepts: both lifetime object and version attribute.

> Clarify this - is 'version' just something that lives on the 'topology' 
> element, or is version something that all elements now contain?  Can we 
> version nodes (e.g. a switch got a firmware update, or new ports added), 
> or links, or ports, or anything else in our universe?

I'm currently only interested in attaching version to a topology, but
wouldn't object to attaching it to other Network Object. What is your
preference? Only attach it to a Topology, or also to Nodes and other
Network Objects?

Regards,
Freek