Re: [Netconf] HTTP2 configured subscriptions, is RESTCONF call home necessary? (was RE: Anyone want just Configured Subscriptions?)
Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Wed, 11 July 2018 05:51 UTC
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Date: Wed, 11 Jul 2018 07:51:54 +0200
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: "Eric Voit (evoit)" <evoit@cisco.com>
Cc: Lou Berger <lberger@labn.net>, Kent Watsen <kwatsen@juniper.net>, Netconf <netconf@ietf.org>
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Subject: Re: [Netconf] HTTP2 configured subscriptions, is RESTCONF call home necessary? (was RE: Anyone want just Configured Subscriptions?)
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On Wed, Jul 11, 2018 at 12:15:45AM +0000, Eric Voit (evoit) wrote: > > From: Juergen Schoenwaelder, July 10, 2018 6:43 PM > > > > On Tue, Jul 10, 2018 at 10:27:23PM +0000, Eric Voit (evoit) wrote: > > > > From: Lou Berger, July 10, 2018 4:43 PM > > > > > > > > On 7/10/2018 4:37 PM, Kent Watsen wrote: > > > > > > > > > >> So in short, after RFC 8071 call home, you get NC/RC client and > > > > >> server starting with a <hello> exchange. Ideally, the client > > > > >> would indicate its readiness to receive unsolicited notifications > > > > >> before you push notifications to the client (and the notification > > > > >> sender may even be interested to know that it is sending > > > > >> notifications to a remote system that does not just drop them). > > > > >> So either the clients invokes an RPC to start the notification > > > > >> flow or, if you want to optimize one round trip, the client > > > > >> includes a special > > > > >> > > > > >> :willing-to-receive-unsolicited-notifications > > > > >> > > > > >> capability in the <hello> exchange. > > > > > I agree that a client-advertised capability would be goodness > > > > > here, but it only works for NC-clients, there is no corollary for RC-clients. > > > > > > > > > > Maybe clients should send a "willing-to-receive-unsolicited-notifications" > > > > > RPC instead? > > > > or an an error when an unsolicited notification is received by a > > > > client that doesn't support it. > > > > (optimizing for what I think suspect will be the common case in the > > > > long > > > > term...) > > > > > > Effectively this is what draft-ietf-netconf-restconf-notif, section 4.2 defines > > now. A successful POST of a "subscription-started" notification must occur > > before events are sent. Failure to receiver an OK for the POST means an error > > to the publisher. > > > > > > Some form of RESTCONF Call Home with capability advertisement could also > > occur before the "subscription-started" POST. However this advertisement of > > client capabilities might not be needed for all implementations. > > > > > > > I fail to understand section 4.2. The first sentence already leaves me > > puzzled: > > > > With HTTP2 connectivity established, a POST of each new > > "subscription-started" state change notification messages will be > > addressed to HTTP augmentation code on the receiver capable of > > accepting and acknowledging to subscription state change > > notifications. > > > > What does this say? And why is this HTTP2 specific? The publisher is the RC > > server, no? > > Actually no. This specification does not use RESTCONF for configured subscriptions. (See other email I just sent to Kent.) OK. So you have a solution for sending dynamic subscriptions via RC but no solution for sending configured subscriptions via RC since you are actually inventing a new protocol for this (which for some unknown reason requires HTTP/2). > > So the RC server does HTTP transactions agains the client? This > > does not seem to have anything to do with how the call home RFC works. > > > > I am not saying that what Figure 3 shows won't work, it just has nothing to do > > with call home. You are reversing the RC client and server roles, call home only > > reverses the connection establishment roles. Big difference. > > Yes this is a big difference. Especially as RESTCONF is removed as well for configured subscriptions. > > Per the other thread, I am actually quite fine with removing call home for configured subscriptions if nobody else sees a need for the receiver to initiate this connection. That would make life simpler. > The receiver? I read in 4.1: If the above conditions are met, then the publisher MUST initiate a transport session via RESTCONF call home [RFC8071], section 4.1 to that receiver. Still puzzled. /js -- Juergen Schoenwaelder Jacobs University Bremen gGmbH Phone: +49 421 200 3587 Campus Ring 1 | 28759 Bremen | Germany Fax: +49 421 200 3103 <https://www.jacobs-university.de/>
- [Netconf] HTTP2 configured subscriptions, is REST… Eric Voit (evoit)
- Re: [Netconf] HTTP2 configured subscriptions, is … Kent Watsen
- Re: [Netconf] HTTP2 configured subscriptions, is … Kent Watsen
- Re: [Netconf] HTTP2 configured subscriptions, is … Juergen Schoenwaelder
- Re: [Netconf] HTTP2 configured subscriptions, is … Eric Voit (evoit)
- Re: [Netconf] HTTP2 configured subscriptions, is … Juergen Schoenwaelder