Hi,
What is the recommended behaviour if the subscription is about to expire
but the subscriber does not want to extend the subscription?
Both RFC 3265 and draft-ietf-sipcore-rfc3265bis seem to focus on long
running subscriptions, which are refreshed indefinitely until explicitly
terminated by an action from the user. While the same could be done for
(seemingly) short term subscriptions, it also makes sense to simply let
the subscription to time out. However RFC 3265 is not very clear on this
topic, only mentioning that:
If a SUBSCRIBE request to refresh a subscription fails [..], the
original subscription is still considered valid for the duration
of the most recently known "Expires" value [..]
I am considering the following options:
* Wait for the final NOTIFY with reason=timeout, and consider the
subscription terminated if it is not received within some fixed time
after the subscription has expired (64*T1 seems like a good choice).
* Explicitly unsubscribe by sending SUBSCRIBE with Expires: 0
* Consider the subscription as terminated as soon as it expires, without
waiting for the final NOTIFY. If the notifier does send it, reply with
481 Subscription Does Not Exist.
By the way, draft-ietf-sipcore-rfc3265bis-09 section 4.2.2 erroneously
states that 'it is perfectly valid for a SUBSCRIBE request with a
non-zero expires to be answered with a NOTIFY request that contains
"Subscription-Status: terminated;reason=expired".' It should be
reason=timeout.
Thanks,
Jānis
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