Jonathan,
Thanks for your comments - see my response below.
Thanks,
Alan
Jonathan Rosenberg wrote:
Alan,
Thanks for putting this together. First some questions:
* is this meant to do a one-time sync? or provide ongoing
synchronization between two event servers? I think your primary use
case is syncing state between a primary and backup, in which case it
would seem to me you'd need this on an ongoing basis, no?
We have found use cases for both. In some cases, just a snapshot is
needed, with some other mechanism being used for ongoing synchronization.
In other cases, perhaps the more common cases, the subscription will be
continued. As a result, since there will be less state to transfer, the
subscription will become a normal one, and probably not use these batch
methods.
* Assuming the primary use case is syncing state between a primary and
backup, these batch notifications don't seem sufficient to make that
work. In the case of presence, you really need the input states to the
compositor - whatever they are - in order to allow the backup to
continue to compute the presence state.
Agreed - for presence, it would be the raw event state rather than any
output from an event state compositor.
Similarly, in the case of conferencing state, the conference itself
would need to move to the backup in order for the backup to continue
to generate event state. If you've moved the conference over anyway,
the backup has the state it needs to generate the event notifications.
So I don't see what is served by the batch notifications.
I agree that the conference state use case is perhaps contrived - it
isn't a real one that we've used it for. I need to think about it some
more. However, I suspect it could be useful for syncing conference
notification servers (as opposed to the actual focus doing the mixing
and signaling).
* is the assumption that the subscription is to ALL state? Or do you
intend that the body of the subscribe could contain, for example, a
list of the URI for which state is desired?
This mechanism should work with filters, so the subscribe could include
a filter body which would change it from all state to filtered state.
And a comment:
* the example shows the server terminating the subscription when it is
'done'. However, the state may have changed since it was sent to the
backup. Seems you have the 'catch the running train problem' of
database state sync and you'd need to continuously keep the
subscription going.
Right - I think this is the more common case. In some cases, a
different mechanism (such as publication) might be used to share ongoing
state after the batch sync is complete. Does that make any sense?
Thanks,
Jonathan R.
--
Jonathan D. Rosenberg, Ph.D. 111 Wood Avenue South
Cisco Fellow Iselin, NJ 08830
Cisco, Voice Technology Group
jdrosen@xxxxxxxxx
http://www.jdrosen.net PHONE: (408) 902-3084
http://www.cisco.com
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