[Nsi-wg] New state machine with two phase reserve and modify

[Chin Guok]

Hi Henrik,
On 7/5/12 2:08 AM, Henrik Thostrup Jensen wrote:
> On Wed, 4 Jul 2012, Chin Guok wrote:
>
>> Actually the IDCP has a single phase reservation workflow.
>
> I stand corrected.
>
>> That is the reason why it explicitly only supports the chain model.
>
> (going off topic here)
>
> Mmm... I do not see why that should restrict it to chain model. Sure 
> tree will be somewhat oppertunistic, but as long as one can cancel the 
> connections I do not see thep roblem. Could you eloborate?
Yes, the cancel operation can accomplish this for a tree, however we 
chose to go the easier route and model it after RSVP.
>
>
> Anyway, my point was that we should be careful about trading a simpler 
> model for a more complex one in order to gain potentially better fault 
> handling. 2PC has problems as well, the main ones being coordinator 
> failures and added implementation complexity.
>
> There is a middleground with oppertunistic methods (e.g., 3PC without 
> the precommit - essentially pre-check + change without any blocking), 
> which provide almost the same functionality but at a much lower 
> implementation cost.
I can see some benefits to what you are proposing.  Do you think you 
would like to expand on this idea and propose a state machine?

Thanks again for the comments.

- Chin
>
> It feels a lot like we are using 2PC for the sake of using 2PC.
>
>
>     Best regards, Henrik
>
>  Henrik Thostrup Jensen <htj at nordu.net>
>  Software Developer, NORDUnet
>
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