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Yang Notifications in Opendaylight and IETF standard

asked 2016-10-31 06:25:39 -0700


I am exploring how notifications are supported in odl over restconf and I landed up here:

Well documented..!! My question is does it comply to the restconf standard as explained here:

As per IETF, subscription is a 3 steps process, client requests stream, server returns streams, client subscribes to one of these stream. But with ODL, it is a 5 steps process, client invokes rpc, server returns streams, client subscribes to stream (get), server returns websocket url, client creates websocket to server.

Regards Kanika

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answered 2016-10-31 13:25:49 -0700

updated 2016-11-01 05:26:44 -0700


Few things:
- ODL does not yet support draft17, but draft02. Here are the diff
- Regardless the above point, both draft share the same specification for the stream subscription, as you pointed out:
1. Client request the list of available streams
2. Server return the available streams
3. Client subscribe to one of the available stream (HTTP GET)


The RFC says, regarding step 3 above:
"The server will treat the connection as an event stream, using the Server Sent Events [wd-eventsource] transport strategy." e.g. create a websocket client using SSE strategy
"The server might send the following response:"
The response being the location of the opened websocket.
But does never specify how to get/listen to this connection, hence I believe this is up to the implementation.


The RFC section you mentioned is for the "Subscribing to Receive Notifications" only.

Looking at the "Event Streams" section, this is where I believe ODL is missing something:
"A RESTCONF server that supports notifications will populate a stream resource for each notification delivery service access point."
As ODL does not populate this automatically (expect for NETCONF device), you have to create the stream yourself.

Hope this helps, Alexis

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Thanks @adetalhouet, how about the 4th and 5th step in ODL, server returning websocket url and client creating websocket connection. IETF draft doesn't talk anything about it, is this left to be decided by whoever is implementing it.

kanika28 ( 2016-11-01 04:55:57 -0700 )edit

I had to edit above question. Please see edit above addressing those questions.

adetalhouet ( 2016-11-01 05:07:59 -0700 )edit

@adetalhouet,sorry I don't follow that, what have you edited?

kanika28 ( 2016-11-01 05:13:38 -0700 )edit

Oh it just got updated

kanika28 ( 2016-11-01 05:14:15 -0700 )edit

I've written my comment before updating the response... I guess that's why you observed the latency.

adetalhouet ( 2016-11-01 05:14:50 -0700 )edit
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Asked: 2016-10-31 06:25:39 -0700

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Last updated: Nov 01 '16