Re: [netconf] HTTPS notifications (draft-ietf-netconf-https-notif)

Martin Bjorklund <mbj@tail-f.com> Tue, 24 September 2019 13:56 UTC

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Subject: Re: [netconf] HTTPS notifications (draft-ietf-netconf-https-notif)
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"Eric Voit (evoit)" <evoit@cisco.com> wrote:
> 
> 
> > > From the email I sent Martin on Sep 9th, each POST MAY contain more
> > > than one notification:
> > 
> > .... to which I replied:
> > 
> >   I'm not so sure about the streaming though.
> >   Perhaps pipelining is the right mechanism.  For "bulk" sending, the
> >   "bundled-message" defined in draft-ietf-netconf-notification-messages
> >   seems right.
> > 
> > To clarify: if the client just sends a stream of notifs it becomes a
> variant of
> > SSE.  The server doesn't know when the stream will end, and thus cannot
> > simply close the session.  You probably want to indicate end-of-message
> > somehow (like in SSE).  And the content type in the example below cannot
> > be "application/yang-data+xml", since it is not a valid XML instance
> > document; you'd have to invent a new media type to indicate the streaming.
> > 
> > I think we should stick to simple HTTP where each notif is POSTed, as in
> your
> > diagaram above.  With HTTP pipelining you can do:
> > 
> > ------> establish TCP
> > ------> establish TLS
> > ------> Send HTTPS POST message with YANG defined notification 1 Send
> > ------> HTTPS POST message with YANG defined notification 2
> > <-----Send 204 (No Content) for 1
> > <-----Send 204 (No Content) for 2
> > 
> > ------> Send HTTPS POST message with YANG defined notification 3
> > <-----Send 204 (No Content) for 3
> > 
> > 
> > If the server wants to send multiple notifs at once, it can use "bundled-
> > message".
> 
> This seems a reasonable approach. draft-ietf-netconf-notification-messages
> has several advantages:
> (1) can push multiple YANG notifications at once
> (2) can include the subscription-id in notifications when subscribing to a
> stream.  (Right now including an explicit subscription-id is only available
> when subscribing to a datastore.)
> (3) includes methods to discover lost/dropped notifications
> 
> Two things which would need to be worked:
> (1) discovering receiver support for bundled notifications.  (As some form
> of understanding/verifying configured receiver support over HTTP is already
> needed, this is a topic which perhaps can be merged into that.)

This can be configured or auto-detected.  For auto-detection, perhaps
we can use HTTP OPTIONS with the server returning a special body or
header to indicate capabilities such as this one?

> (2) Completion of draft-ietf-netmod-yang-data-ext 

Yes!  IMO it is ready for WGLC; I'll ping the chairs again.


/martin



> 
> Eric
> 
> > /martin
> > 
> > 
> > >
> > >     POST /some/path HTTP/1.1
> > >     Host: my-receiver.my-domain.com <http://my-receiver.my-
> > domain.com/>
> > >     Content-Type: application/yang-data+xml
> > >
> > >     <notification
> > >       xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
> > >       <eventTime>2019-03-22T12:35:00Z</eventTime>
> > >       <foo xmlns="https://example.com
> > >       <https://example.com/>/my-foobar-module">
> > >         ...
> > >       </foo>
> > >     </notification>
> > >
> > >     <notification
> > >       xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
> > >       <eventTime>2019-03-22T12:35:00Z</eventTime>
> > >       <bar xmlns="https://example.com
> > >       <https://example.com/>/my-foobar-module">
> > >         ...
> > >       </bar>
> > >     </notification>
> > >
> > >     <notification
> > >       xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
> > >       <eventTime>2019-03-22T12:35:00Z</eventTime>
> > >       <baz xmlns="https://example.com
> > >       <https://example.com/>/my-foobar-module">
> > >         ...
> > >       </baz>
> > >     </notification>
> > >
> > >
> > > With response:
> > >
> > >       HTTP/1.1 204 No Content
> > >       Date: Thu, 26 Jan 2017 20:56:30 GMT
> > >       Server: my-receiver.my-domain.com
> > > <http://my-receiver.my-domain.com/>
> > >
> > >
> > > Kent // co-author
> > >
> > >
> > 
> > _______________________________________________
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> > netconf@ietf.org
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