Hi Nicholas, [RFC3265 extracts] > If the value of the "Subscription-State" header is "active" or > "pending", the notifier SHOULD also include in the "Subscription- > State" header an "expires" parameter which indicates the time > remaining on the subscription. > ... > If the "Subscription-State" header value is "active", it means that > the subscription has been accepted and (in general) has been > authorized. If the header also contains an "expires" parameter, the > subscriber SHOULD take it as the authoritative subscription duration > and adjust accordingly.
> So if there is 5 seconds left on a subscription, and a client receives > a NOTIFY, the client changes the Expires of any subsequent SUBSCRIBEs > for that event to 5 seconds, and requires a refresh at less than 5 > second intervals. The longer the client runs, the smaller this value > will become. I think you have misunderstood RFC3265 in this matter. If the client receives a NOTIFY with "Expires: 5", it should infer that the current subscription will expire in 5 seconds. If it wishes to extend the subscription, it will need to send a reSUBSCRIBE. It does not need to resubscribe with an expiry of 5 seconds! Instead, it may choose a different one (whatever worked the first time would be a good choice). So, a typical flow could look something like this: SUBSCRIBE (Expires:180) ---> # Initial subscribe requesting 180 secs <--- 200 <--- NOTIFY (Expires: 180) # Note need to resubscribe in 180 secs 200 ---> (time passes (137 secs), something happens) <--- NOTIFY (Expires: 43) # Note need to resubscribe in 43 secs 200 ---> (another 23 seconds pass, client decides to extend subscription, as only 20 seconds remain) SUBSCRIBE (Expires: 180) ---> <--- 200 <--- NOTIFY (Expires: 180) # Subscription extended for 3 mins 200 ---> I hope this clarifies things, Michael _______________________________________________ Sip mailing list https://www1.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
