Based on Hadriels use cases, I'd like to suggest some litmus tests that
one can use to help determine if something is best done by INFO or
something else:
Cases where a media-plane session is the best solution:
* there are requirements for low latency delivery (camera control for
example)
* there are requirements that the data shouldn't be retransmitted
since latency trumps reliability (coordinate updates for a pointer on a
whiteboard or something like that)
* the data consists of a large number of messages that are likely to
be sent during the duration of the session
* the data is potentially very large
Cases where SUB-NOT is the best solution:
* the entity that wants to receive the data knows with high
probability that the other side is likely to send a notification with
the data, and it knows specifically what type of data it needs to receive
* the entity that wants to receive the data is likely to receive a
multiplicity of events containing that data
Cases where INFO is the best solution:
* the recipient of the data has no idea if the sender will ever
generate the data; the recipient is just saying that it knows how to
handle it, should the sender have something to send
* the recipient could potentially handle many different types of data
with the above characteristic
* the size of the data that is to be sent is small and infrequent, at
most a few times during the session
* the data needs to be sent reliably and latency is not much of an issue
* the data has no impact on SIP dialog state, transaction state,
media session states or intermediate proxy or b2bua states
-Jonathan R.
--
Jonathan D. Rosenberg, Ph.D. 499 Thornall St.
Cisco Fellow Edison, NJ 08837
Cisco, Voice Technology Group
[EMAIL PROTECTED]
http://www.jdrosen.net PHONE: (408) 902-3084
http://www.cisco.com
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