So I understand the need for the subscription migration; but let's take this a step further. Let's say there's no registrar. We're talking straight peer-to-peer. Is this a valid scenario, or is this why most UAs basically FORCE the user to register before doing presence?
Adam Roach wrote:
From the mile-high view, the way you would make such a system work is this:
1) A registers with the registrar and sends a SUBSCRIBE message to B 2) B is not registered, so the registrar "parks" the subscribe. That is, the registrar accepts the subscription and sends a presence document for "B" indicating "closed." (Note that the registrar isn't really acting as a presence server here; it is just acting as a parking lot for subscriptions). 3) B starts and registers with the registrar 4) The registrar sends a NOTIFY to A with a "Subscription-State" header of "terminated", and a reason parameter of "deactivated". 5) A sends a SUBSCRIBE message to B 6) B accepts the registrations, and things go forward normally.
This is the *precise* scenario that motivates all the text in RFC 3265 surrounding migration.
/a
-----Original Message----- From: David Stuart [mailto:[EMAIL PROTECTED] Sent: Monday, August 25, 2003 10:20 To: SIP Implementors Subject: [Sip-implementors] Achieving up to date presence info without PUBLISH
Hi All,
I have a question about the manner in which presence info is kept up to date, assuming that the PUBLISH draft is not in the picture. Basically just assume peer to peer presence for the purpose of this question.
Say I have two user agents, A and B.
1) A registers with the registrar and sends a SUBSCRIBE message to B
2) B is not running, so B does not receive the SUBSCRIBE message
3) A sets a presence of "closed" or "unknown" (or something similar) for B
4) B starts and registers with the registrar
result: A has an incorrect current presence for B.
What I am wondering is, how can you avoid this situation? Does A have to "poll" periodically for B (i.e. a "fetch")? Without any help from an intermediary presence server (which is running 24/7) it seems that you would always need to poll.
What is the usual agreed upon polling interval? An hour? 10 minutes? 1 minute? 2 seconds?
Any help would be appreciated.
Thanks,
-- David Stuart, SIPquest Email: dave (at) sipquest (dot) com Phone: 254-8886 x234 Web: http://www.sipquest.com/ Address: 106 - 350 Terry Fox Drive, Kanata Ontario, K2K 2P5
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-- David Stuart, SIPquest Email: dave (at) sipquest (dot) com Phone: 254-8886 x234 Web: http://www.sipquest.com/ Address: 106 - 350 Terry Fox Drive, Kanata Ontario, K2K 2P5
_______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
