Re: [Stox] Review for stox-7248bis-02
"Ben Campbell" <ben@nostrum.com> Mon, 03 August 2015 19:45 UTC
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From: Ben Campbell <ben@nostrum.com>
To: Peter Saint-Andre - &yet <peter@andyet.net>
Date: Mon, 03 Aug 2015 14:45:29 -0500
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Cc: stox@ietf.org, rjsparks@nostrum.com, Isomaki Markus <markus.isomaki@nokia.com>
Subject: Re: [Stox] Review for stox-7248bis-02
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Hi, A couple of thoughts on this: The additional text in 04 about waiting for a NOTIFY with an active state helps. But it might be worth adding an initial "pending" notify exchange to (at least) 5.2.1. On the architectural question: I think that the "more complex" architecture is also the more relevant one. But, you could ignore this completely by just changing "SIP User" to "Presence Server" in 5.2.* . Unless I'm forgetting something, the architectural questions should not change the interactions to the left of the presence server. Then the architectural note could simply state that this may be a separate presence server, or it may be co-located with the SIP UA, but the relevant XMPP to SIP flow is the same either way. Also,the idea of a SIP "server" is architecturally vague--there's no such animal defined in the SIP standards. I suggest calling it a SIP Proxy in 5.2.*. In 5.3.*, it could either be a "SIP Proxy + S2X GW", or just a "S2X GW" Ben. On 26 Jul 2015, at 16:22, Peter Saint-Andre - &yet wrote: > I've posted -04 to address this feedback. > > Peter > > On 7/23/15 12:04 AM, Peter Saint-Andre - &yet wrote: >> Hi Markus, thanks for the continued review. >> >> On 7/22/15 6:30 AM, Isomaki Markus (Nokia-TECH/Espoo) wrote: >>> Hi Peter, >>> >>> I checked the revised draft (-03) and it addresses the issues I >>> raised >>> below. But that brought up another thing still. It's been really >>> long >>> since I've been dealing with SIP Presence, but I think that the >>> message flows in 4.2.1 may still need a couple of clarifications: >>> >>> 1.) >>> >>> In SIP, if the subscription is not immediately authorized (neither >>> accepted or rejected), it is possible that a 200 OK response to the >>> SUBSCRIBE is sent immediately followed by a NOTIFY with subscription >>> state "pending". If the SIP User later on positively authorizes the >>> subscription, another NOTIFY with subscription state "active" is >>> generated. The potential "pending" state does not seem to be covered >>> in the current diagram, but it probably should be. The question is >>> just what happens in XMPP-to-SIP GW if it gets a NOTIFY with >>> "pending" >>> subscription state. To my understanding the subscription state would >>> remain "neutral" on the XMPP side. Would that mean that the >>> XMPP-to-SIP GW would not send anything to the XMPP side in that >>> case, >>> i.e. only a NOTIFY indicating subscription state as "active" would >>> cause the message (F10) to be triggered? In that case, maybe this >>> kind >>> of addition would be enough: >>> >>> OLD: >>> >>> In accordance with [RFC6665], the XMPP-to-SIP gateway SHOULD >>> consider >>> the subscription state to be "neutral" until it receives a NOTIFY >>> message. Therefore, the SIP user or SIP server at the SIP user's >>> domain SHOULD immediately send a NOTIFY message containing a >>> Subscription-State header [RFC6665] whose value contains the string >>> "active" (see Section 5 below). >>> >>> NEW: >>> >>> In accordance with [RFC6665], the XMPP-to-SIP gateway SHOULD >>> consider >>> the subscription state to be "neutral" until it receives a NOTIFY >>> message. Therefore, the SIP user or SIP server at the SIP user's >>> domain SHOULD immediately send a NOTIFY message containing a >>> Subscription-State header [RFC6665] with value "active" (see >>> Section 5 >>> below). In case the XMPP-to-SIP gateway initially receives one or >>> more >>> NOTIFY messages with Subscription-State "pending", it MUST respond >>> to them on the SIP side, but not generate any presence stanzas >>> towards the >>> XMPP User. >> >> That it better. The only further change I would make is: >> >> In accordance with [RFC6665], the XMPP-to-SIP gateway SHOULD >> consider >> the subscription state to be "neutral" until it receives a NOTIFY >> message with a Subscription-State header [RFC6665] whose value is >> "active". >> >> Also, I think it would make sense to change SHOULD to MUST here. >> >>> 2.) >>> >>> If you look at RFCs 3856 and 3857, the typical scenario in SIP >>> presence is: There is a SIP Presence Server handling the >>> subscriptions >>> to the presence event package. That is where the SUBSCRIBE (F2) in >>> 4.2.1 goes. But typically the Presence Server would not forward the >>> SUBSCRIBE to the SIP User in way shown in (F3). Instead, the >>> Presence >>> Server and SIP User would interact via the 'presence.winfo' event >>> package (RFC 3857), to which the SIP User would be subcribed. So, >>> when >>> the Presence Server gets a SUBSCRIBE to SIP User's Presence, it >>> generates a 'presence.winfo' NOTIFY the SIP User, who will that way >>> learn about the new subscription. The SIP User would then authorize >>> the subscription by some interaction (for instance using XCAP) with >>> the Presence Server. In this scenario, presence updates from the SIP >>> User would also not be sent as NOTIFYs, but as PUBLISH messages to >>> the >>> Presence Server, who would then generate NOTIFYs to all active >>> subscribers. >>> >>> It is however possible that the Presence Server acts in a Proxy >>> mode, >>> in which case (as far as I remember), it just passes the SUBSCRIBEs >>> and NOTIFYs through as in the current diagram in 4.2.1. If we don't >>> want to go into the more complex diagrams, it would suffice just to >>> say (already in terminology or in 4.2.1): "In these examples it is >>> assumed that the SIP Server acts as a proxy for Presence event >>> package >>> and the actual Presence Agent resides with the SIP User." >> >> Yes, the latter seems reasonable. However, also pointing to RFC 3857 >> seems like a good idea. >> >> Peter >>
- [Stox] Review for stox-7248bis-02 Isomaki Markus (Nokia-TECH/Espoo)
- Re: [Stox] Review for stox-7248bis-02 Peter Saint-Andre - &yet
- Re: [Stox] Review for stox-7248bis-02 Isomaki Markus (Nokia-TECH/Espoo)
- Re: [Stox] Review for stox-7248bis-02 Peter Saint-Andre - &yet
- Re: [Stox] Review for stox-7248bis-02 Peter Saint-Andre - &yet
- Re: [Stox] Review for stox-7248bis-02 Saúl Ibarra Corretgé
- Re: [Stox] Review for stox-7248bis-02 Peter Saint-Andre
- Re: [Stox] Review for stox-7248bis-02 Ben Campbell
- Re: [Stox] Review for stox-7248bis-02 Isomaki Markus (Nokia-TECH/Espoo)
- Re: [Stox] Review for stox-7248bis-02 Peter Saint-Andre - &yet