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draft-ietf-netconf-distributed-notif-01.xml
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<?xml version="1.0" encoding="US-ASCII"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?rfc toc="yes"?>
<?rfc tocompact="yes"?>
<?rfc tocdepth="3"?>
<?rfc tocindent="yes"?>
<?rfc symrefs="yes"?>
<?rfc sortrefs="yes"?>
<?rfc comments="yes"?>
<?rfc inline="yes"?>
<?rfc compact="yes"?>
<?rfc subcompact="no"?>
<rfc category="std" docName="draft-ietf-netconf-distributed-notif-01"
ipr="trust200902">
<front>
<title abbrev="Distributed Notifications">Subscription to Distributed
Notifications</title>
<author fullname="Tianran Zhou" initials="T." surname="Zhou">
<organization>Huawei</organization>
<address>
<postal>
<street>156 Beiqing Rd., Haidian District</street>
<city>Beijing</city>
<region/>
<code/>
<country>China</country>
</postal>
<phone/>
<facsimile/>
<email>[email protected]</email>
<uri/>
</address>
</author>
<author fullname="Guangying Zheng" initials="G." surname="Zheng">
<organization>Huawei</organization>
<address>
<postal>
<street>101 Yu-Hua-Tai Software Road</street>
<city>Nanjing</city>
<code/>
<region>Jiangsu</region>
<country>China</country>
</postal>
<phone/>
<facsimile/>
<email>[email protected]</email>
</address>
</author>
<author fullname="Eric Voit" initials="E." surname="Voit">
<organization>Cisco Systems</organization>
<address>
<postal>
<street/>
<city/>
<code/>
<region/>
<country>United States of America</country>
</postal>
<phone/>
<facsimile/>
<email>[email protected]</email>
</address>
</author>
<author fullname="Thomas Graf" initials="T." surname="Graf">
<organization>Swisscom</organization>
<address>
<postal>
<street>Binzring 17</street>
<city>Zuerich 8045</city>
<region/>
<code/>
<country>Switzerland</country>
</postal>
<phone/>
<facsimile/>
<email>[email protected]</email>
<uri/>
</address>
</author>
<author fullname="Pierre Francois" initials="P." surname="Francois">
<organization>INSA-Lyon</organization>
<address>
<postal>
<street/>
<city>Lyon</city>
<region/>
<code/>
<country>France</country>
</postal>
<phone/>
<facsimile/>
<email>[email protected]</email>
<uri/>
</address>
</author>
<date day="02" month="November" year="2020"/>
<workgroup>NETCONF</workgroup>
<abstract>
<t>This documents describes extensions to the YANG notifications
subscription to allow metrics being published directly from processors
on line cards to target receivers, while subscription is still
maintained at the route processor in a distributed forwarding
system.</t>
</abstract>
<note title="Requirements Language">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in <xref
target="RFC2119">RFC 2119</xref>.</t>
</note>
</front>
<middle>
<section title="Introduction">
<t>The mechanism to support a subscription to a continuous and
customized stream of updates from a YANG datastore is defined in <xref
target="RFC8639"/> and <xref target="RFC8641"/>. Requirements for
Subscription to YANG Datastores are defined in <xref
target="RFC7923"/></t>
<t>By streaming data from publishers to receivers, much better
performance and fine-grained sampling can be achieved than with polling.
In a distributed forwarding system, the packet forwarding is delegated
to multiple processors on line cards. To not to overhelm the route
processor resources, it is not uncomon that data records are published
directly from processors on line cards to target Receivers to further
increase efficency on the routing system.</t>
<t>This documents complement the general subscription requirements
defined in section 4.2.1 of <xref target="RFC7923"/> by the paragraph: A
Subscription Service MAY support the ability to export from multiple
software processes on a single routing system and expose the information
which software process produced which message to maintain data
integrity.</t>
</section>
<section title="Terminologies">
<t>The following terms are defined in <xref target="RFC8639"/> and are
not redefined here:</t>
<t>Subscriber</t>
<t>Publisher</t>
<t>Receiver</t>
<t>Subscription</t>
<t>In addition, this document defines the following terms:</t>
<t>Global Subscription: the Subscription requested by the subscriber. It
may be decomposed into multiple Component Subscriptions.</t>
<t>Component Subscription: is the Subscription that defines a data
source which is managed and controlled by a single Publisher.</t>
<t>Global Capability: is the overall subscription capability that the
group of Publishers can expose to the Subscriber.</t>
<t>Component Capability: is the subscription capability that each
Publisher can expose to the Subscriber.</t>
<t>Master: is the Publisher that interacts with the Subscriber to deal
with the Global Subscription. It decomposes the Global Subscription to
multiple Component Subscriptions and interacts with the Agents.</t>
<t>Agent: is the Publisher that interacts with the Master to deal with
the Component Subscription and pushing the data to the collector.</t>
<t>Observation Domain: An Observation Domain is the largest set of
Observation Points for which metrics can be collected by a metering
process. For example, a router line card may be an Observation Domain if
it is composed of several interfaces, each of which is an Observation
Point. In the YANG notification messages it generates, the Observation
Domain includes its Observation Domain ID, which is unique per publisher
process. That way, the collecting process can identify the specific
Observation Domain from the publisher that sends the YANG notification
messages. Every Observation Point is associated with an Observation
Domain.</t>
<t>Observation Domain ID: A 32-bit identifier of the Observation Domain
that is locally unique to the publisher process. The publisher process
uses the Observation Domain ID to uniquely identify to the collecting
process the Observation Domain that meters the metrics. Receivers SHOULD
use the transport session and the Observation Domain ID field to
separate different publisher streams originating from the same
publisher.</t>
</section>
<section title="Motivation">
<t>Lost and corrupt YANG notification messages need to be recognized at
the receiver to ensure data integrity even when multiple publisher
processes publishing from the same transport session.</t>
<t>To preserve data integrity down to the publisher process, the
Observation Domain ID in the transport message header of the YANG
notification message is introduced. In case of UDP transport, this is
described in Section 3.2 of <xref target="I-D.ietf-netconf-udp-notif">
UDP based transport</xref>.</t>
</section>
<section title="Solution Overview">
<t>Figure 2 below shows the distributed data export framework.</t>
<t>A collector usually includes two components,</t>
<t><list style="symbols">
<t>the Subscriber generates the subscription instructions to express
what and how the collector want to receive the data;</t>
<t>the Receiver is the target for the data publication.</t>
</list></t>
<t>For one subscription, there are one or more Receivers. And the
Subscriber does not necessarily share the same IP address as the
Receivers.</t>
<t>In this framework, the Publisher pushes data to the Receiver
according to the subscription. The Publisher is either in the Master or
Agent role. The Master knows all the capabilities that his Agents are
able to provide and exposes the Global Capability to the collector. The
Subscriber maintains the Global Subscription at the Master and
disassembles the Global Subscription to multiple Component
Subscriptions, depending from which source data is needed. The Component
Subscriptions are then distributed to the corresponding Publisher Agents
on route and processors on line cards.</t>
<t>Publisher Agents collects metrics according to the Component
Subscription, add its metadata, encapsulate and pushes data to the
Receiver where packets are reassembled and decapsulated.</t>
<t><figure title="Fig. 2 The Distributed Data Export Framework">
<artwork align="center"><![CDATA[
+-----------------------------------------+
| Collector |-------------+ |
| +------------+ | |
| +------------+ || Receiver | | |
| | Subscriber | |--------------+ |
| +-----^-+----+ +------------^ |
| | | | |
+-----------------------------------------+
Global | | Global |
Capability| | Subscription |
+-----------------------------------------+
| | | | |
| +--------+-v-------------------+ | |
| | Publisher(Master) | | |
| +--------^-+-------------------+ | |
| | | | |
| | | | |
| Component | | Component Push | |
| Capability| | Subscription | |
| +--------+-v-------------------+ | |
| | Publisher(Agent) +--+ |
| +------------------------------+ |
| |
| Device |
+-----------------------------------------+
]]></artwork>
</figure></t>
<t>Master and Agents interact with each other in several ways: <list
style="symbols">
<t>Agents need to register at the Master at the beginning of their
process life-cycle</t>
<t>Contracts are created between the Master and each Agent on the
Component Capability, and the format for streaming data
structure.</t>
<t>The Master relays the component subscriptions to the Agents.</t>
<t>The Agents announce the status of their Component Subscriptions
to the Master. The status of the overall subscription is maintained
by the Master. The Master is responsible for notifying the
subscriber in case of problems with the Component Subscriptions.</t>
</list>The technical mechanisms or protocols used for the coordination
of operational information between Master and Agent is out-of-scope of
this document.</t>
</section>
<section title="Subscription Decomposition">
<t>The Collector can only subscribe to the Master. This requires the
Master to:</t>
<t><list style="numbers">
<t>expose the Global Capability that can be served by multiple
Publisher Agents;</t>
<t>disassemble the Global Subscription to multiple Component
Subscriptions, and distribute them to the Publisher Agents of the
corresponding metric sources so that they not overlap;</t>
<t>notify on changes when portions of a subscription moving between
different Publisher Agents over time.</t>
</list></t>
<t>And the Agent to:</t>
<t><list style="symbols">
<t>Inherit the Global Subscription properties from Publisher Master
for its Component Subscription;</t>
<t>share the same life-cycle as the Global Subscription;</t>
<t>share the same Subscription ID as the Global Subscription.</t>
</list></t>
</section>
<section title="Publication Composition">
<t>The Publisher Agent collects data and encapsulates the packets per
Component Subscription. The format and structure of the data records are
defined by the YANG schema, so that the decomposition at the Receiver
can benefit from the structured and hierarchical data records.</t>
<t>The Receiver is able to associate the YANG data records with <xref
target="RFC8639">Subscription ID</xref> to the subscribed subscription
and with <xref target="I-D.ietf-netconf-notification-messages">Message
Observation Domain ID</xref> to one of the Publisher Agents software
processes to enable message integrity.</t>
<t>For the dynamic subscription, the output of the
"establish-subscription" RPC defined in <xref target="RFC8639"/> MUST
include a list of Message Observation Domain IDs to indicate how the
Global Subscription is decomposed into several Component
Subscriptions.</t>
<t>The "subscription-started" and "subscription-modified" notification
defined in <xref target="RFC8639"/> MUST also include a list of Message
Observation Domain IDs to notify the current Publishers for the
corresponding Global Subscription.</t>
</section>
<section title="Subscription State Change Notifications">
<t>In addition to sending event records to Receivers, the Master MUST
also send <xref target="RFC8639">subscription state change
notifications</xref> when events related to subscription management have
occurred. All the subscription state change notifications MUST be
delivered by the Master.</t>
<t>When the subscription decomposition result changed, the
"subscription-modified" notification MUST be sent to indicate the new
list of Publishers.</t>
</section>
<section title="Publisher Configurations">
<t>This document assumes that all Publisher Agents are preconfigured to
push data. The actual working Publisher Agents are selected based on the
subscription decomposition result.</t>
<t>All Publisher Agents share the same source IP address for data
export. For connectionless data transport such as <xref
target="I-D.ietf-netconf-udp-notif">UDP based transport</xref> the same
Layer 4 source port for data export can be used. For connection based
data transport such as <xref target="I-D.ietf-netconf-https-notif">
HTTPS based transport</xref>, each Publisher Agent MUST be able to
acknowledge packet retrieval from Receivers, and therefore requires a
dedicated Layer 4 source port per software process.</t>
<t>The specific configuration on transports is described in the
resposible documents.</t>
</section>
<section title="YANG Tree">
<t/>
<t><figure>
<artwork><![CDATA[
module: ietf-distributed-notifications
augment /sn:subscriptions/sn:subscription:
+--ro message-observation-domain-id* string
augment /sn:subscription-started:
+--ro message-observation-domain-id* string
augment /sn:subscription-modified:
+--ro message-observation-domain-id* string
augment /sn:establish-subscription/sn:output:
+--ro message-observation-domain-id* string
]]></artwork>
</figure></t>
</section>
<section title="YANG Module">
<t/>
<t><figure>
<artwork><![CDATA[
<CODE BEGINS> file "[email protected]"
module ietf-distributed-notif {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-distributed-notifications";
prefix mso;
import ietf-subscribed-notifications {
prefix sn;
}
organization "IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http:/tools.ietf.org/wg/netconf/>
WG List: <mailto:[email protected]>
Editor: Tianran Zhou
<mailto:[email protected]>
Editor: Guangying Zheng
<mailto:[email protected]>";
description
"Defines augmentation for ietf-subscribed-notifications to
enable the distributed publication with single subscription.
Copyright (c) 2018 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Simplified BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the
RFC itself for full legal notices.";
revision 2020-05-09 {
description
"Initial version";
reference
"RFC XXXX: Subscription to Distributed Notifications";
}
grouping message-observation-domain-ids {
description
"Provides a reusable list of message-observation-domain-ids.";
leaf-list message-observation-domain-id {
type string;
config false;
ordered-by user;
description
"Software process which created the message (e.g.,
processor 1 on linecard 1). This field is
used to notify the collector the working originator.";
}
}
augment "/sn:subscriptions/sn:subscription" {
description
"This augmentation allows the message
Observation Domain ID to be exposed for a subscription.";
uses message-observation-domain-ids;
}
augment "/sn:subscription-started" {
description
"This augmentation allows MSO specific parameters to be
exposed for a subscription.";
uses message-observation-domain-ids;
}
augment "/sn:subscription-modified" {
description
"This augmentation allows MSO specific parameters to be
exposed for a subscription.";
uses message-observation-domain-ids;
}
augment "/sn:establish-subscription/sn:output" {
description
"This augmentation allows MSO specific parameters to be
exposed for a subscription.";
uses message-observation-domain-ids;
}
}
<CODE ENDS>
]]></artwork>
</figure></t>
</section>
<section anchor="IANA" title="IANA Considerations">
<t>This document registers the following namespace URI in the <xref
target="RFC3688">IETF XML Registry</xref>:</t>
<t><list style="empty">
<t>URI:
urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications</t>
<t>Registrant Contact: The IESG.</t>
<t>XML: N/A; the requested URI is an XML namespace.</t>
</list>This document registers the following YANG module in the <xref
target="RFC3688">YANG Module Names registry</xref>:</t>
<t><list style="empty">
<t>Name: ietf-subscribed-notifications</t>
<t>Namespace:
urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications</t>
<t>Prefix: mso</t>
<t>Reference: RFC XXXX</t>
</list></t>
</section>
<section anchor="Security" title="Security Considerations">
<t>The YANG module specified in this document defines a schema for data
that is designed to be accessed via network management protocols such as
<xref target="RFC6241">NETCONF</xref> or <xref
target="RFC8040">RESTCONF</xref>. The lowest NETCONF layer is the secure
transport layer, and the mandatory-to-implement secure transport is
<xref target="RFC6242">Secure Shell (SSH)</xref>. The lowest RESTCONF
layer is HTTPS, and the mandatory-to-implement secure transport is <xref
target="RFC5246">TLS</xref>.</t>
<t>The NETCONF <xref target="RFC6536">Access Control Model (NACM)</xref>
provides the means to restrict access for particular NETCONF or RESTCONF
users to a preconfigured subset of all available NETCONF or RESTCONF
protocol operations and content.</t>
<t>The new data nodes introduced in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus
important to control read access (e.g., via get-config or notification)
to this data nodes. These are the subtrees and data nodes and their
sensitivity/vulnerability:</t>
<t><list style="symbols">
<t>/subscriptions/subscription/message-observation-domain-ids</t>
</list>The entries in the two lists above will show where subscribed
resources might be located on the publishers. Access control MUST be set
so that only someone with proper access permissions has the ability to
access this resource.</t>
<t>Other Security Considerations is the same as those discussed in <xref
target="RFC8641">YANG-Push</xref>.</t>
</section>
<section title="Contributors">
<figure>
<artwork><![CDATA[ Alexander Clemm
Futurewai
2330 Central Expressway
Santa Clara
California
United States of America
Email: [email protected]]]></artwork>
</figure>
</section>
<section anchor="Acknowledgements" title="Acknowledgements">
<t>We thank Kent Watsen, Mahesh Jethanandani, Martin Bjorklund, Tim
Carey and Qin Wu for their constructive suggestions for improving this
document.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.2119"?>
<?rfc include='reference.RFC.5246'?>
<?rfc include='reference.RFC.3688'?>
<?rfc include='reference.RFC.6241'?>
<?rfc include='reference.RFC.8040'?>
<?rfc include='reference.RFC.8639'?>
<?rfc include='reference.RFC.8641'?>
<?rfc include='reference.RFC.6536'?>
<?rfc include='reference.RFC.6242'?>
<?rfc include='reference.RFC.7923'?>
</references>
<references title="Informative References">
<?rfc include="reference.I-D.ietf-netconf-notification-messages"?>
<reference anchor="I-D.ietf-netconf-udp-notif" target="">
<front>
<title>UDP-based Transport for Configured Subscriptions</title>
<author fullname="Tianran Zhou" initials="T." surname="Zhou">
<organization>Huawei</organization>
</author>
<author fullname="Guangying Zheng" initials="G." surname="Zheng">
<organization>Huawei</organization>
</author>
<author fullname="Paolo Lucente" initials="P." surname="Lucente">
<organization>NTT</organization>
</author>
<author fullname="Thomas Graf" initials="T." surname="Graf">
<organization>Swisscom</organization>
</author>
<author fullname="Pierre Francois" initials="P." surname="Francois">
<organization>INSA-Lyon</organization>
</author>
<date month="July" year="2020"/>
</front>
<seriesInfo name="Internet-Draft"
value="draft-ietf-netconf-udp-notif-01"/>
</reference>
<?rfc include='reference.I-D.ietf-netconf-https-notif'?>
</references>
<section title="Examples">
<t>This appendix is non-normative.</t>
<section title="Dynamic Subscription">
<t>Figure 3 shows a typical dynamic subscription to the device with
distributed data export capability.</t>
<t><figure title="Fig. 3 Call Flow for Dynamic Subscription">
<artwork><![CDATA[
+-------------+ +-------------+ +-------------+
| Subscriber/ | | Publisher | | Publisher |
| Receiver | | (Master) | | (Agent) |
+-------------+ +------+------+ +------+------+
| | |
| establish-subscription | |
+------------------------------>+ component |
| | subscription |
| RPC Reply: OK, id #22 +-------------->+
| Observation Domain ID [#1,#2] | |
+<------------------------------+ |
| | |
| notif-mesg, id #22 | |
| Observation Domain ID #1 | |
+<------------------------------+ |
| | |
| notif-mesg, id#22 | |
| Observation Domain ID #2 | |
+<----------------------------------------------+
| | |
| modify-subscription (id#22) | |
+------------------------------>+ component |
| | subscription |
| RPC Reply: OK, id #22 +-------------->+
+<------------------------------+ |
| | |
| subscription-modified, id#22 | |
| Observation Domain ID [#1] | |
+<------------------------------+ |
| | |
| notif-mesg, id #22 | |
| Observation Domain ID #1 | |
+<------------------------------+ |
| | |
| | |
+ + +
]]></artwork>
</figure></t>
<t>A "establish-subscription" RPC request as per <xref
target="RFC8641"/> is sent to the Master with a successful response.
An example of using NETCONF:</t>
<t><figure title="Fig. 4 "establish-subscription" Request">
<artwork><![CDATA[
<netconf:rpc message-id="101"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<establish-subscription
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:operational
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:ex="https://example.com/sample-data/1.0">
/ex:foo
</yp:datastore-xpath-filter>
<yp:periodic>
<yp:period>500</yp:period>
</yp:periodic>
</establish-subscription>
</netconf:rpc>]]></artwork>
</figure>As the device is able to fully satisfy the request, the
request is given a subscription ID of 22. The response as in Figure 5
indicates that the subscription is decomposed into two component
subscriptions which will be published by two message Observation
Domain ID: #1 and #2.</t>
<t><figure
title="Fig. 5 "establish-subscription" Positive RPC Response">
<artwork><![CDATA[<rpc-reply message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<id
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications">
22
</id>
<message-observation-domain-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications>
1
</message-observation-domain-id>
<message-observation-domain-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications>
2
</message-observation-domain-id>
</rpc-reply>]]></artwork>
</figure>Then, both Publishers send notifications with the
corresponding piece of data to the Receiver.</t>
<t>The subscriber may invoke the "modify-subscription" RPC for a
subscription it previously established. The RPC has no difference to
the single publisher case as in [RFC8641]. Figure 6 provides an
example where a subscriber attempts to modify the period and datastore
XPath filter of a subscription using NETCONF.</t>
<t><figure title="Fig. 6 "modify-subscription" Request">
<artwork><![CDATA[ <rpc message-id="102"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<modify-subscription
xmlns=
"urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<id>22</id>
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:operational
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:ex="https://example.com/sample-data/1.0">
/ex:bar
</yp:datastore-xpath-filter>
<yp:periodic>
<yp:period>250</yp:period>
</yp:periodic>
</modify-subscription>
</rpc>]]></artwork>
</figure></t>
<t>If the modification is successfully accepted, the
"subscription-modified" subscription state notification is sent to the
subscriber by the Master. The notification, Figure 7 for example,
indicates the modified subscription is decomposed into one component
subscription which will be published by message Observation Domain
#1.</t>
<t><figure
title="Fig. 7 "subscription-modified" Subscription State Notification">
<artwork><![CDATA[<notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-modified
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<id>22</id>
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:operational
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:ex="https://example.com/sample-data/1.0">
/ex:bar
</yp:datastore-xpath-filter>
<yp:periodic>
<yp:period>250</yp:period>
</yp:periodic>
<message-observation-domain-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notificationss>
1
</message-observation-domain-id>
</subscription-modified>
</notification>]]></artwork>
</figure></t>
<t/>
</section>
<section title="Configured Subscription">
<t>Figure 8 shows a typical configured subscription to the device with
distributed data export capability.</t>
<t/>
<t><figure title="Fig. 8 Call Flow for Configured Subscription">
<artwork><![CDATA[
+-------------+ +-------------+ +-------------+
| Receiver | | Publisher | | Publisher |
| | | (Master) | | (Agent) |
+------+------+ +------+------+ +------+------+
| | |
| subscription-started, id#39 | |
| Observation Domain ID [#1,#2] | |
+<------------------------------+ |
| | |
| notif-mesg, id#39 | |
| Observation Domain ID #1 | |
+<------------------------------+ |
| | |
| notif-mesg, id#39 | |
| Observation Domain ID #2 | |
+<----------------------------------------------+
| | |
| | |
| | |
]]></artwork>
</figure></t>
<t>Before starting to push data, the "subscription-started"
subscription state notification is sent to the Receiver. The following
example assumes the NETCONF transport has already established. The
notification indicates that the configured subscription is decomposed
into two component subscriptions which will be published by two
message Observation Domain: #1 and #2.</t>
<t><figure
title="Fig. 9 "subscription-started" Subscription State Notification">
<artwork><![CDATA[
<notification xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<subscription-started
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<identifier>39</identifier>
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:operational
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:ex="https://example.com/sample-data/1.0">
/ex:foo
</yp:datastore-xpath-filter>
<yp:periodic>
<yp:period>250</yp:period>
</yp:periodic>
<message-observation-domain-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications>
1
</message-observation-domain-id>
<message-observation-domain-id
xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications>
2
</message-observation-domain-id>
</subscription-started>
</notification>]]></artwork>
</figure></t>
<t>Then, both Publishers send notifications with the corresponding
data record to the Receiver.</t>
</section>
</section>
</back>
</rfc>