Re: [sipX-dev] XX-4591 When an established subscription ends, the RLS should resubscribe
On Mon, 2009-06-15 at 10:06 -0400, Beeton, Carolyn (CAR:9D60) wrote:
> Part of the BLA I-D
> (http://tools.ietf.org/html/draft-anil-sipping-bla-02) says (section 8):
> "the State Agent MUST SUBSCRIBE
> with a shorter expiration (expiration interval not smaller than 300
> seconds is RECOMMENDED) following the notification of a 'confirmed'
> dialog or when a Event Agent honors a 'trying' for call origination,
> with the user agents that notified it of this information." (the
> purpose being to avoid tying up a shared line if one set dies while
> holding it).
>
> To support this, I was planning to add an interface to the
> SipSubscribeClient and the SipRefreshManager to change the subscribe
> timeout. I am not sure how this would interact with what is proposed
> here. I would want to see a failure response right away, so that the
> shared line could be freed for other users.
The current proposal is that failure responses (either of the initial
subscribe or of a re-subscribe) are reflected to the application
promptly, which is the current behavior, so I don't think the XX-4591
fix will cause the SAA a problem.
However, looking at changeXxxTimer, it looks like it only gives
reasonable results if it is applied to an established subscription. I
don't think that is a problem in practice. But there is some
interaction between the user-requested refresh time and the
retry/backoff algorithms, particularly the fact that the user-requested
refresh time can change dynamically.
Dale
