-
Notifications
You must be signed in to change notification settings - Fork 1
/
draft-ietf-netconf-subscribed-notifications-09-pre-release-draft.xml
2342 lines (2035 loc) · 118 KB
/
draft-ietf-netconf-subscribed-notifications-09-pre-release-draft.xml
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
<?xml version="1.0" encoding="US-ASCII"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?rfc toc="yes"?>
<?rfc tocompact="yes"?>
<?rfc tocdepth="2"?>
<?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-subscribed-notifications-09" ipr="trust200902">
<front>
<title abbrev="Subscribed Notifications">Custom Subscription to Event Streams</title>
<author fullname="Eric Voit" initials="E." surname="Voit">
<organization>Cisco Systems</organization>
<address>
<email>[email protected]</email>
</address>
</author>
<author fullname="Alexander Clemm" initials="A" surname="Clemm">
<organization>Huawei</organization>
<address>
<email>[email protected]</email>
</address>
</author>
<author fullname="Alberto Gonzalez Prieto" initials="A"
surname="Gonzalez Prieto">
<organization>VMWare</organization>
<address>
<email>[email protected]</email>
</address>
</author>
<author fullname="Einar Nilsen-Nygaard" initials="E"
surname="Nilsen-Nygaard">
<organization>Cisco Systems</organization>
<address>
<email>[email protected]</email>
</address>
</author>
<author fullname="Ambika Prasad Tripathy" initials="A" surname="Tripathy">
<organization>Cisco Systems</organization>
<address>
<email>[email protected]</email>
</address>
</author>
<date day="24" month="January" year="2018"/>
<area>Operations & Management</area>
<workgroup>NETCONF</workgroup>
<keyword>Draft</keyword>
<abstract>
<t>This document defines capabilities and operations for the customized establishment of subscriptions upon a publisher's event streams. Also defined are delivery mechanisms for instances of the resulting notification messages. Effectively this allows a subscriber to request and receive a continuous, custom feed of publisher generated information.</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>This document defines capabilities and operations for the customized establishment of subscriptions upon system generated event streams. Effectively this enables a "subscribe then publish" capability where the customized information needs of each target receiver are understood by the publisher before subscribed event records are marshaled and pushed. The receiver then gets a continuous, custom feed of publisher generated information.</t>
<t>While the functionality defined in this document is transport-agnostic, protocols like NETCONF <xref target="RFC6241"/> or RESTCONF <xref target="RFC8040"/> can be used to configure or dynamically signal subscriptions, and there are bindings defined for subscribed event record delivery for NETCONF within <xref target="I-D.draft-ietf-netconf-netconf-event-notifications"/>, and for HTTP2 or HTTP1.1 within <xref target="I-D.draft-ietf-netconf-restconf-notif"/>.</t>
<section title="Motivation">
<t>There are various <xref target="RFC5277"/> limitations, many of which have been exposed in <xref target="RFC7923"/> which needed to be solved. Key capabilities supported by this document include:</t>
<t><list style="symbols">
<t>multiple subscriptions on a single transport session</t>
<t>support for dynamic and statically configured subscriptions</t>
<t>modification of an existing subscription</t>
<t>operational counters and instrumentation</t>
<t>negotiation of subscription parameters (through the use of hints returned as part of declined subscription requests)</t>
<t>state change notifications (e.g., publisher driven suspension, parameter modification)</t>
<t>independence from transport protocol</t>
</list></t>
</section>
<section title="Terminology">
<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>
<t>Configured subscription: A subscription installed via a configuration interface which persists across reboots.</t>
<t>Dynamic subscription: A subscription agreed between subscriber and publisher created via an establish-subscription RPC.</t>
<t>Event: An occurrence of something that may be of interest. (e.g., a configuration change, a fault, a change in status, crossing a threshold, or an external input to the system.)</t>
<t>Event record: A set of information detailing an event.</t>
<t>NACM: NETCONF Access Control Model.</t>
<t>Notification message: A set of transport encapsulated information intended for a receiver indicating that one or more event(s) have occurred. A notification message may bundle multiple event records. This includes the bundling multiple, independent RFC 7950 YANG notifications.</t>
<t>Publisher: An entity responsible for streaming notification messages per the terms of a Subscription.</t>
<t>Receiver: A target to which a publisher pushes subscribed event records. For dynamic subscriptions, the receiver and subscriber are the same entity.</t>
<t>Stream (also referred to as "event stream"): A continuous ordered set of events aggregated under some context.</t>
<t>Stream filter: Evaluation criteria which may be applied against event records within a stream. Event records pass the filter when specified criteria are met.</t>
<t>Subscribed event records: Event records which have met the terms of the subscription. This include terms (such as security checks) enforced by the publisher.</t>
<t>Subscriber: An entity able to request and negotiate a contract for the generation and push of event records from a publisher.</t>
<t>Subscription: A contract with a publisher, stipulating which information one or more receivers wish to have pushed from the publisher without the need for further solicitation.</t>
</section>
<section title="Solution Overview">
<t>This document describes a transport agnostic mechanism for subscribing to and receiving content from a stream instantiated within a publisher. This mechanism is through the use of a subscription.</t>
<t>Two types of subscriptions are supported:</t>
<t><list style="numbers">
<t>Dynamic subscriptions, where a subscriber initiates a subscription negotiation with a publisher via RPC. If the publisher wants to serve this request, it accepts it, and then starts pushing notification messages. If the publisher does not wish to serve it as requested, then an error response is returned. This response MAY include hints at subscription parameters which would have been accepted.</t>
<t>Configured subscriptions, which allow the management of subscriptions via a configuration interface so that a publisher can send notification messages to configured receiver(s). Support for this capability is optional.</t>
</list></t>
<t>Additional characteristics differentiating configured from dynamic subscriptions include:</t>
<t><list style="symbols">
<t>The lifetime of a dynamic subscription is bounded by the transport session used to establish it. For connection-oriented stateful transport like NETCONF, the loss of the transport session will result in the immediate termination of any associated dynamic subscriptions. For connectionless or stateless transports like HTTP, a lack of receipt acknowledgment of a sequential set of notification messages and/or keep-alives can be used to trigger a termination of a dynamic subscription. Contrast this to the lifetime of a configured subscription. This lifetime is driven by relevant configuration being present within the publisher's running configuration. Being tied to configuration operations implies configured subscriptions can be configured to persist across reboots, and implies a configured subscription can persist even when its publisher is fully disconnected from any network.</t>
<t>Configured subscriptions can be modified by any configuration client with write permission on the configuration of the subscription. Dynamic subscriptions can only be modified via an RPC request made by the original subscriber.</t>
</list></t>
<t>Note that there is no mixing-and-matching of dynamic and configured operations on a single subscriptions. Specifically, a configured subscription cannot be modified or deleted using RPCs defined in this document. Similarly, a subscription established via RPC cannot be modified through configuration operations. Also note that transport specific transport drafts based on this specification MUST detail the life cycles of both dynamic and configured subscriptions.</t>
<t>The publisher MAY decide to terminate a dynamic subscription at any time. Similarly, it MAY decide to temporarily suspend the sending of notification messages for any dynamic subscription, or for one or more receivers of a configured subscription. Such termination or suspension is driven by internal considerations of the publisher.</t>
</section>
<section title="Relationship to RFC-5277">
<t>This document is intended to provide a superset of the subscription capabilities initially defined within <xref target="RFC5277"/>. Especially when extending an existing <xref target="RFC5277"/> implementation, it is important to understand what has been reused and what has been replaced. Key relationships between these two documents include:
<list style="symbols">
<t>the data model in this document replaces the data model in <xref target="RFC5277"/>.</t>
<t>the RPC operations in this draft replaces the symmetrical operations of <xref target="RFC5277"/>, section 4.</t>
<t>the one way operation of <xref target="RFC5277"/> is still used. However this operation will no longer be required with the availability of <xref target="I.D.draft-ietf-netconf-notification-messages"/>. </t>
<t>the definition and contents of the NETCONF stream are identical between this document and <xref target="RFC5277"/>.</t>
<t>a publisher MAY implement both the data model and RPCs defined in <xref target="RFC5277"/> and this new document concurrently, in order to support old clients. However the use of both alternatives on a single transport session is prohibited.</t>
</list>
</t>
</section>
</section>
<section title="Solution">
<section title="Event Streams">
<t>An event stream is a named entity on a publisher which exposes a continuously updating set of event records. Each event stream is available for subscription. It is out of the scope of this document to identify a) how streams are defined, b) how event records are defined/generated, and c) how event records are assigned to streams.</t>
<t>There is only one reserved event stream within this document: NETCONF. The NETCONF event stream contains all NETCONF XML event record information supported by the publisher, except for where it has been explicitly indicated that this the event record MUST be excluded from the NETCONF stream. The NETCONF stream will include individual YANG notifications as per <xref target="RFC7950"/> section 7.16. Each of these YANG notifications will be treated a distinct event record. Beyond the NETCONF stream, implementations are free to add additional event streams.</t>
<t>As event records are created by a system, they may be assigned to one or more streams. The event record is distributed to subscription's receiver(s) where: (1) a subscription includes the identified stream, and (2) subscription filtering does not exclude the event record from that receiver.</t>
<t>If access control permissions are in use to secure publisher content, then for event records to be sent to a receiver, that receiver MUST be allowed access to all the event records on the stream. If subscriber permissions change during the lifecycle of a subscription, then the subscription MUST be continued or terminated accordingly.</t>
</section>
<section title="Event Stream Filters">
<t>This document defines an extensible filtering mechanism. Two optional stream filtering syntaxes supported are <xref target="XPATH"/> and subtree <xref target="RFC6241"/>. A filter always removes a complete event record; a subset of information is never stripped from an event record.</t>
<t>If no stream filter is provided within a subscription, all event records on a stream are to be sent.</t>
</section>
<section title="QoS">
<t>This document provides an optional feature describing QoS parameters. These parameters indicate the treatment of a subscription relative to other traffic between publisher and receiver. Included are:
<list style="symbols">
<t>A "dscp" QoS marking to differentiate transport QoS behavior. Where provided, this marking MUST be stamped on notification messages.</t>
<t>A "weighting" so that bandwidth proportional to this weighting can be allocated to this subscription relative to other subscriptions destined for that receiver.</t>
<t>a "dependency" upon another subscription. Notification messages MUST NOT be sent prior to other notification messages containing update record(s) for the referenced subscription.</t>
</list>
</t>
<t>A subscription's weighting MUST work identically to stream dependency weighting as described within RFC 7540, section 5.3.2.</t>
<t>A subscription's dependency MUST work identically to stream dependency as described within <xref target="RFC7540"/>, sections 5.3.1, 5.3.3, and 5.3.4. If a dependency is attempted via an RPC, but the referenced subscription does not exist, the dependency will be silently removed.</t>
</section>
<section title="Dynamic Subscriptions" anchor="dynamic_subs">
<t>Dynamic subscriptions are managed via RPC, and are made against targets located within the publisher. These RPCs have been designed extensibly so that they may be augmented for subscription targets beyond event streams.</t>
<section title="Dynamic Subscription State Model">
<t>Below is the publisher's state machine for a dynamic subscription. It is important to note that such a subscription doesn't exist at the publisher until it an "establish-subscription" RPC is accepted. The mere request by a subscriber to establish a subscription is insufficient for that asserted subscription to be externally visible.</t>
<figure align="center" title="Dynamic subscription state">
<artwork align="left"><![CDATA[
.-------.
| start |
'-------'
|
establish-subscription
|
| .------modify-subscription-------.
v v '
.-----------. .-----------.
.--------. | receiver |-subscription-suspended->| receiver |
modify- '| active | | suspended |
subscription | |<--subscription-resumed--| |
---------->'-----------' '-----------'
| |
delete/kill-subscription delete/kill-
| subscription
v |
.-------. |
| end |<-------------------------------'
'-------'
]]></artwork>
</figure>
<t>Of interest in this state machine are the following:
<list style="symbols">
<t>Successful establish or modify RPCs put the subscription into an active state.</t>
<t>Failed modify RPCs will leave the subscription in its previous state, with no visible change to any streaming updates.</t>
<t>A delete or kill RPC will end the subscription.</t>
<t>Suspend and resume state changes are driven by internal process and prioritization. There are no direct controls over suspend and resume other than modifying a subscription</t>
</list></t>
</section>
<section title="Establishing a Subscription" anchor="sec_establish_subs">
<t>The "establish-subscription" operation allows a subscriber to request the creation of a subscription via RPC. It MUST be possible to support multiple establish subscription RPC requests made within the same transport session.</t>
<t>The input parameters of the operation are:
<list style="symbols">
<t>A stream name which identifies the targeted stream of events against which the subscription is applied.</t>
<t>A stream filter which may reduce the set of event records pushed.</t>
<t>An optional encoding for the event records pushed. Note: If no encoding is included, the encoding of the RPC MUST be used.</t>
<t>An optional stop time for the subscription. If no stop-time is present, notification messages will continue to be sent until the subscription is terminated.</t>
<t>An optional start time which indicates that this subscription is requesting a replay of previously generated information from the event stream. For more on replay, see <xref target="replay_subs"/>.</t>
</list>
</t>
<t>If the publisher can satisfy the "establish-subscription" request, it provides an identifier for the subscription, and immediately starts streaming notification messages. </t>
<figure align="center" title="establish-subscription RPC"
anchor="establish-subscription-RPC">
<artwork align="left"><![CDATA[
+---x establish-subscription
+---w input
| +---w encoding? encoding
| +---w (target)
| | +--:(stream)
| | +---w (stream-filter)?
| | | +--:(by-reference)
| | | | +---w stream-filter-ref stream-filter-ref
| | | +--:(within-subscription)
| | | +---w (filter-spec)?
| | | +--:(stream-subtree-filter)
| | | | +---w stream-subtree-filter? {subtree}?
| | | +--:(stream-xpath-filter)
| | | +---w stream-xpath-filter?
| | | yang:xpath1.0 {xpath}?
| | +---w stream? stream-ref
| | +---w replay-start-time? yang:date-and-time {replay}?
| +---w stop-time? yang:date-and-time
| +---w dscp? inet:dscp {qos}?
| +---w weighting? uint8 {qos}?
| +---w dependency? sn:subscription-id {qos}?
+--ro output
+--ro identifier subscription-id
]]></artwork>
</figure>
<t>A publisher MAY reject this RPC for many reasons as described in <xref target="appendix_a1"/>. The contents of the resulting RPC error response MAY include one or more hints on alternative inputs which would have resulted in a successfully established subscription. Such hints MUST be transported within a yang-data "establish-subscription-error-stream" container included within the RPC error response.</t>
<figure align="center" title="establish-subscription RPC yang-data"
anchor="establish-subscription-RPC-yang-data">
<artwork align="left"><![CDATA[
yang-data establish-subscription-error-stream
+--ro establish-subscription-error-stream
+--ro reason? identityref
+--ro filter-failure-hint? string
+--ro replay-start-time-hint? yang:date-and-time
]]></artwork>
</figure>
<section title="Replay Subscription" anchor="replay_subs">
<t>Replay provides the ability to establish a subscription which is also capable of passing recently generated event records. In other words, as the subscription initializes itself, it sends any previously generated content from within target event stream which meets the filter and timeframe criteria. These historical event records would then be followed by event records generated after the subscription has been established. All event records will be delivered in the order generated.</t>
<t>Replay is an optional feature which is dependent on an event stream supporting some form of logging. Replay puts no restrictions on the size or form of the log, or where it resides within the device.</t>
<t>The inclusion of a replay-start-time within an "establish-subscription" RPC indicates a replay request. If the "replay-start-time" contains a value that is earlier than content stored within the publisher's replay buffer, then the subscription MUST be rejected, and the leaf "replay-start-time-hint" MUST be set in the reply.</t>
<t>If a "stop-time" parameter is included, it MAY also be earlier than the current time and MUST be later than the "replay-start-time". The publisher MUST NOT accept a "replay-start-time" for a future time.</t>
<t>If the "replay-start-time" is later than any information stored in the replay buffer, then the publisher MUST send a "replay-completed" notification immediately after the "subscription-started" notification.</t>
<t>If a stream supports replay, the "replay-support" leaf is present in the "/streams/stream" list entry for the stream. An event stream that does support replay is not expected to have an unlimited supply of saved notifications available to accommodate any given replay request. To assess the availability of replay, subscribers can perform a get on "replay-log-creation-time" and "replay-log-aged-time". See <xref target="stream-tree"/> for the tree describing these elements. The actual size of the replay log at any given time is a publisher specific matter. Control parameters for the replay log are outside the scope of this document.</t>
</section>
</section>
<section title="Modifying a Subscription">
<t>The "modify-subscription" operation permits changing the terms of an existing dynamic subscription previously established on that transport session via "establish-subscription". Dynamic subscriptions can be modified one or multiple times. If the publisher accepts the requested modifications, it replies with "ok", then immediately starts sending event records based on the new terms.</t>
<t>Dynamic subscriptions established via RPC can only be modified via RPC using the same transport session used to establish that subscription. Subscriptions created by configuration operations cannot be modified via this RPC.</t>
<figure align="center" title="modify-subscription RPC"
anchor="modify-subscription-RPC">
<artwork align="left"><![CDATA[
+---x modify-subscription
+---w input
| +---w identifier? subscription-id
| +---w (target)
| | +--:(stream)
| | +---w (stream-filter)?
| | +--:(by-reference)
| | | +---w stream-filter-ref stream-filter-ref
| | +--:(within-subscription)
| | +---w (filter-spec)?
| | +--:(stream-subtree-filter)
| | | +---w stream-subtree-filter? {subtree}?
| | +--:(stream-xpath-filter)
| | +---w stream-xpath-filter?
| | yang:xpath1.0 {xpath}?
| +---w stop-time? yang:date-and-time
+--ro output
+--ro ok empty
]]></artwork>
</figure>
<t>If the publisher accepts the requested modifications on a currently suspended subscription, the subscription will immediately be resumed (i.e., the modified subscription is returned to an active status.) The publisher MAY immediately suspend this newly modified subscription through the "subscription-suspended" notification before any event records are sent.</t>
<t>If the publisher rejects the RPC request, the subscription remains as prior to the request. That is, the request has no impact whatsoever. Rejection of the RPC for any reason is indicated by via RPC error as described in <xref target="appendix_a1"/>. The contents of a such a rejected RPC MAY include one or more hints on alternative inputs which would have resulted in a successfully modified subscription. These hints MUST be transported within a yang-data "modify-subscription-error-stream" container inserted into the RPC error response.</t>
<figure align="center" title="modify-subscription RPC yang-data"
anchor="modify-subscription-RPC-yang-data">
<artwork align="left"><![CDATA[
yang-data modify-subscription-error-stream
+--ro modify-subscription-error-stream
+--ro reason? identityref
+--ro filter-failure-hint? string
]]></artwork>
</figure>
</section>
<section title="Deleting a Subscription">
<t>The "delete-subscription" operation permits canceling an existing subscription previously established on that transport session. If the publisher accepts the request, and the publisher has indicated this success via an "ok", the publisher MUST NOT send any more notification messages for this subscription. If the publisher rejects the request, the request has no impact whatsoever on any subscription.</t>
<figure align="center" title="delete-subscription RPC"
anchor="delete-subscription-RPC">
<artwork align="left"><![CDATA[
+---x delete-subscription
+---w input
| +---w identifier subscription-id
+--ro output
+--ro ok empty
]]></artwork>
</figure>
<t>Dynamic subscriptions can only be deleted via this RPC using the same transport session previously used for subscription establishment. Configured subscriptions cannot be deleted using RPCs.</t>
</section>
<section title="Killing a Subscription">
<t>The "kill-subscription" operation permits an operator to end a dynamic subscription which is not associated with the transport session used for the RPC. This operation MUST be secured so that only connections with sufficiently privileged access rights are able to invoke this RPC. A publisher MUST terminate any dynamic subscription identified by RPC request. An operator may find subscription identifiers which may be used with "kill-subscription" by searching for the IP address of a receiver within "subscriptions\subscription\receivers\receiver\address".</t>
<t>Configured subscriptions cannot be killed using this RPC. Instead, configured subscriptions are deleted as part of regular configuration operations. Publishers MUST reject any RPC attempt to kill a configured subscription.</t>
<t>The tree structure of "kill-subscription" is almost identical to "delete-subscription", with only the name of the RPC and yang-data changing.</t>
</section>
</section>
<section title="Configured Subscriptions">
<t>A configured subscription is a subscription installed via a configuration interface. Configured subscriptions may be modified by any configuration client with the proper permissions. Subscriptions can be modified or terminated via the configuration interface at any point of their lifetime.</t>
<t>Configured subscriptions have several characteristics distinguishing them from dynamic subscriptions:
<list style="symbols">
<t>persistence across reboots,</t>
<t>persistence even when transport is unavailable, and</t>
<t>an ability to send notification messages to more than one receiver (note that the publisher does not provide information to a receiver about other receivers.)</t>
</list>
</t>
<t>Supporting configured subscriptions is optional and advertised using the "configured" feature. </t>
<t>In addition to subscription parameters available to dynamic subscriptions as described in <xref target="sec_establish_subs"/>, the following additional parameters are also available to configured subscriptions:
<list style="symbols">
<t>One or more receiver IP addresses (and corresponding ports) intended as the destination for notification messages.</t>
<t>Optional parameters to identify an egress interface, a host IP address, a VRF (as defined by the network instance name within <xref target="I-D.draft-ietf-rtgwg-ni-model"/>), or an IP address plus VRF out of which notification messages are to be pushed from the publisher. Where any of this info is not explicitly included, or where just the VRF is provided, notification messages MUST egress the publisher's default interface towards that receiver.</t>
</list>
</t>
<section title="Configured Subscription State Model">
<t>Below is the state machine for a configured subscription. The creation or modification of a configured subscription initiates a publisher evaluation to determine if the subscription is valid or invalid. The publisher uses its own criteria in making this determination. If valid, the subscription becomes operational. </t>
<figure align="center"
title="Configured subscription status.">
<artwork align="left"><![CDATA[
.-------.
| start |-.
'-------' |
create .---modify-----.----------------------------------.
| | | |
V V .-------. .-----. .---------.
.----[evaluate]--no--->|invalid|-delete->| end |<-delete-|concluded|
| '-------' '-----' '---------'
|----[evaluate]--no-. ^ ^ ^
| ^ | | | |
yes | '->unsupportable delete stop-time
| modify (subscription- (subscription- (subscription-
| | terminated) terminated) concluded)
| | | | |
| .---------------------------------------------------------------.
'-->| valid |
'---------------------------------------------------------------'
]]></artwork>
</figure>
<t>A valid subscription may become invalid on one of two ways. First, it may be modified in a way which fails a re-evaluation. Second, the publisher itself might itself determine that the subscription in no longer supportable. In either case, a "subscription-terminated" notification is sent to any active or suspended receivers. A valid subscription may also transition to a concluded status if a configured stop time has been reached. In this case, a "subscription-concluded" is sent to any active or suspended receivers.</t>
<t>During any times a subscription is considered valid, a publisher will attempt to connect with all configured receivers and deliver notification messages. Below is the state machine for each receiver of a configured subscription. This receiver state machine itself is fully contained within the state machine of the configured subscription, and is only relevant when the configured subscription itself is determined to be valid.</t>
<figure align="center"
title="Configured receiver state">
<artwork align="left"><![CDATA[
.----------------------------------------------------------------.
| valid |
| .----------. .--------. |
| | receiver |------------------timeout->|receiver| |
| |connecting|<------------------reset---|timeout | |
| | |<-transport---. '--------' |
| '----------' loss,reset | |
| | | | |
| (subscription | | |
| started) .--------. | .---------. |
| '----->| | '----------------------| | |
| |receiver|-(subscription-suspended)-->|receiver | |
|(subscription-| active | |suspended| |
| modified) | |<-(subscription-resumed,----| | |
| '---->'--------' subscription-modified) '---------' |
'----------------------------------------------------------------'
]]></artwork>
</figure>
<t>When a subscription first becomes valid, the operational status of each receiver is initialized to connecting. Individual are receivers are moved to an active status when a "subscription-started" state change notification is successfully passed to that receiver. Configured receivers remain active if transport connectivity is not lost, and event records are not being dropped due to a publisher buffer overflow. A configured subscription's receiver MUST be moved to connecting if transport connectivity is lost, or if the receiver is reset via configuration operations.</t>
<t>A configured subscription's receiver MUST be moved to a suspended state if there is transport connectivity between the publisher and receiver, but notification messages are not being generated for that receiver. A configured subscription receiver MUST be returned to an active state from the suspended state when notification messages are again being generated and a receiver has successfully been sent a "subscription-resumed" or a "subscription-modified".</t>
<t>Modification of a configured subscription is possible at any time. A "subscription-modified" state change notification will be sent to all active receivers, immediately followed by notification messages conforming to the new parameters. Suspended receivers will also be informed of the modification. However this notification will await the end of the suspension for that receiver.</t>
<t>The mechanisms described above is mirrored in the RPCs and YANG notifications within the document. It should be noted that these RPCs and YANG notifications have been designed to be extensible and allow subscriptions into targets other than event streams. <xref target="I-D.ietf-netconf-yang-push"/> provides an example of such an extension.</t>
</section>
<section title="Creating a Configured Subscription" anchor="sec_create_config_subs">
<t>Configured subscriptions are established using configuration operations against the top-level subtree "subscription-config". There are two key differences between the new RPCs defined in this document and configuration operations for subscription creation. Firstly, configuration operations install a subscription without question, while the RPCs are designed to the support negotiation and rejection of requests. Secondly, while the RPCs mandate that the subscriber establishing the subscription is the only receiver of the notification messages, configuration operations permit specifying receivers independent of any tracked subscriber. Because there is no explicit association with an existing transport session, configuration operations require additional parameters beyond those of dynamic subscriptions to indicate receivers, and possibly whether the notification messages need to come from a specific egress interface on the publisher.</t>
<t>After a subscription is successfully created, the publisher immediately sends a "subscription-started" state change notification to each receiver. It is quite possible that upon configuration, reboot, or even steady-state operations, a transport session may not be currently available to the receiver. In this case, when there is something to transport for an active subscription, transport specific call-home operations will be used to establish the connection. When transport connectivity is available, notification messages may then be pushed.</t>
<t>With active configured subscriptions, it is allowable to buffer event records even after a "subscription-started" has been sent. However if events are lost (rather than just delayed) due to replay buffer overflow, a new "subscription-started" must be sent. This new "subscription-started" indicates an event record discontinuity.</t>
<t>To see an example at subscription creation using configuration operations over NETCONF, see Appendix A of <xref target="I-D.draft-ietf-netconf-netconf-event-notifications"/>.</t>
<t>Note that is possible to configure replay on a configured subscription. This capability is to allow a configured subscription to exist on a system so that event records generated during boot can be buffered and pushed as soon as the transport session is established.</t>
</section>
<section title="Modifying a Configured Subscription">
<t>Configured subscriptions can be modified using configuration operations against the top-level subtree "subscription-config".</t>
<t>If the modification involves adding receivers, added receivers are placed in the "connecting" state. If a receiver is removed, the state change notification "subscription-terminated" is sent to that receiver if that receiver is "active" or "suspended" .</t>
<t>If the modification involved changing the policies for the subscription, the publisher sends to currently active receivers a "subscription-modified" notification. For any suspended receivers, a "subscription-modified" notification will be delayed until the receiver is resumed. (Note: in this case, the "subscription-modified" notification informs the receiver that the subscription has been resumed, so no additional "subscription-resumed" need be sent.)</t>
</section>
<section title="Deleting a Configured Subscription">
<t>Subscriptions can be deleted using configuration operations against the top-level subtree "subscription-config".</t>
<t>Immediately after a subscription is successfully deleted, the publisher sends to all receivers of that subscription a state change notification stating the subscription has ended (i.e., "subscription-terminated").</t>
</section>
<section title="Resetting a Configured Receiver">
<t>It is possible that a configured subscription to a receiver needs to be reset. This re-initialization may be useful in cases where a publisher has timed out trying to reach a receiver. When such a reset occurs, a transport session will be initiated if necessary, and a new "subscription-started" notification will be sent.</t>
</section>
</section>
<section title="Event Record Delivery">
<t>Whether dynamic or configured, once a subscription has been set up, the publisher streams event records via notification messages per the terms of the subscription. For dynamic subscriptions set up via RPC operations, notification messages are sent over the session used to establish the subscription. For configured subscriptions, notification messages are sent over the connections specified by the transport, plus receiver IP address and port configured.</t>
<t>A notification message is sent to a receiver when an event record is able to traverse the specified filter criteria. This notification message MUST be encoded as one-way notification element of <xref target="RFC5277"/>, Section 4. The following example within <xref target="RFC7950"/> section 7.16.3 is an example of a compliant message:</t>
<figure align="center" anchor="simple-data-plane-notif" title="subscribed notification message">
<artwork align="left"><![CDATA[
<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<link-failure xmlns="http://acme.example.com/system">
<if-name>so-1/2/3.0</if-name>
<if-admin-status>up</if-admin-status>
<if-oper-status>down</if-oper-status>
</link-failure>
</notification>
]]></artwork>
</figure>
<t>This [RFC5277] section 4 one-way operation has the drawback of not including useful header information such as a subscription identifier. When using this mechanism, it is left up to implementations or augmentations to this document to determine which event records belong to which subscription.</t>
<t>These drawbacks, along with other useful common headers and the ability to bundle multiple event records together is being explored within <xref target="I.D.draft-ietf-netconf-notification-messages"/>. When the notification-messages is supported, this document will be updated to indicate support.</t>
</section>
<section title="Subscription State Notifications" anchor="state_notif">
<t>In addition to subscribed event records, a publisher will send subscription state notifications to indicate to receivers that an event related to the subscription management has occurred.</t>
<t>Subscription state notifications are unlike other notifications which might be found in the event stream. They cannot be filtered out, and they are delivered only to directly impacted receiver(s) of a subscription. The identification of subscription state notifications is easy to separate from other notification messages through the use of the YANG extension "subscription-state-notif". This extension tags a notification as subscription state notification. </t>
<t>The complete set of subscription state notifications is described in the following subsections.</t>
<section title="subscription-started">
<t>This notification indicates that a configured subscription has started, and event records may be sent. Included in this state change notification are all the parameters of the subscription, except for the receiver(s) addressing information and origin information indicating where notification messages will egress the publisher. Note that if a referenced filter from the "filters" container has been used within the subscription, the notification will include the contents of that referenced under the "within-subscription" subtree.</t>
<t>Note that for dynamic subscriptions, no "subscription-started" notifications are ever sent.</t>
<figure align="center" title="subscription-started notification"
anchor="subscription-started-notification">
<artwork align="left"><![CDATA[
+---n subscription-started {configured}?
+--ro identifier subscription-id
+--ro protocol transport {configured}?
+--ro encoding encoding
+--ro (target)
| +--:(stream)
| +--ro (stream-filter)?
| | +--:(by-reference)
| | | +--ro stream-filter-ref stream-filter-ref
| | +--:(within-subscription)
| | +--ro (filter-spec)?
| | +--:(stream-subtree-filter)
| | | +--ro stream-subtree-filter? {subtree}?
| | +--:(stream-xpath-filter)
| | +--ro stream-xpath-filter? yang:xpath1.0 {xpath}?
| +--ro stream stream
| +--ro replay-start-time? yang:date-and-time {replay}?
+--ro stop-time? yang:date-and-time
+--ro dscp? inet:dscp {qos}?
+--ro weighting? uint8 {qos}?
+--ro dependency? sn:subscription-id {qos}?
]]></artwork>
</figure>
</section>
<section title="subscription-modified">
<t>This notification indicates that a subscription has been modified by configuration operations. The same parameters of "subscription-started" are provided via this notification. As a result, the tree structure of "subscription-modified" is almost identical to "subscription-started", with only the name of the notification changing.</t>
<t>A publisher most often sends this notification directly after the modification of any configuration parameters impacting a configured subscription. But it may also be sent at two other times.
<list style="symbols">
<t>First, where a configured subscription has been modified during the suspension of a receiver, the notification will be delayed until the receiver's suspension is lifted. In this situation, the notification indicates that the subscription has been both modified and resumed.</t>
<t>Second, for dynamic subscriptions, there is one and only one time this notification may be sent. A "subscription-modified" state change notifications MUST be sent if the contents of a filter identified by a "stream-filter-ref" has changed.</t>
</list></t>
</section>
<section title="subscription-terminated">
<t>This notification indicates that a subscription has been terminated on the publisher. The state change notification includes the reason for the termination. Viable reasons are described in <xref target="appendix_a2"/>.</t>
<t>The publisher MAY decide to terminate a subscription rather than continuing to serve it. Such a decision may be made when a publisher runs out of resources, an internal error occurs, or some other reason. Publisher-driven terminations are always notified to all receivers.</t>
<t>Subscribers themselves can terminate existing subscriptions established via a "delete-subscription" RPC. In such cases, no "subscription-terminated" state change notifications are sent. However if a "kill-subscription" RPC is sent, or some other event other than reaching the subscription's stop time results in the end of a subscription, then this state change notification MUST be sent. </t>
<figure align="center" title="subscription-terminated notification"
anchor="subscription-terminated-notification">
<artwork align="left"><![CDATA[
+---n subscription-terminated
+--ro identifier subscription-id
+--ro error-id subscription-errors
+--ro filter-failure? string
]]></artwork>
</figure>
</section>
<section title="subscription-suspended">
<t>This notification indicates that a publisher has suspended the sending of event records to a receiver, and also indicates the possible loss of events. The state change notification includes the reason for the suspension as described in <xref target="appendix_a2"/>. No further notification will be sent until the subscription resumes or is terminated. </t>
<t>The tree structure of "subscription-suspended" is almost identical to "subscription-terminated", with only the name of the notification changing.</t>
</section>
<section title="subscription-resumed">
<t>This indicates that a previously suspended subscription has been resumed under the unmodified terms previously in place. Subscribed event records generated after the generation of this state change notification will be sent.</t>
<figure align="center" title="subscription-resumed notification"
anchor="subscription-resumed-notification">
<artwork align="left"><![CDATA[
+---n subscription-resumed
+--ro identifier subscription-id
]]></artwork>
</figure>
</section>
<section title="subscription-completed">
<t>This notification indicates that a subscription, which includes a "stop-time", has successfully finished passing event records upon the reaching of that time.</t>
<t>The tree structure of "subscription-completed" is almost identical to "subscription-resumed", with only the name of the notification changing.</t>
</section>
<section title="replay-completed">
<t>This notification indicates that all of the event records prior to the current time have been sent. This includes new event records generated since the start of the subscription. This notification MUST NOT be sent for any other reason. </t>
<t>If subscription contains no "stop-time", or has a "stop-time" which has not been reached, then after the "replay-completed" notification has been sent, additional event records will be sent in sequence as they arise naturally on the publisher.</t>
<t>The tree structure of "replay-completed" is almost identical to "subscription-resumed", with only the name of the notification changing.</t>
</section>
</section>
<section title="Subscription Monitoring">
<t>Container "subscriptions" in the YANG module contains the state of all known subscriptions. This includes subscriptions that were established (and have not yet been deleted) using RPCs, as well as subscriptions that have been configured as part of configuration. Using the "get" operation with NETCONF, or subscribing to this information via <xref target="I-D.ietf-netconf-yang-push"/> allows the status of subscriptions to be monitored.</t>
<t>Each subscription is represented as a list element. The associated information includes an identifier for the subscription, receiver counter information, the status of the subscription, as well as the various subscription parameters that are in effect. The subscription status indicates the subscription's state with each receiver (e.g., is currently active or suspended). Leaf "configured-subscription" indicates whether the subscription came into being via configuration or via RPC.</t>
<t>Subscriptions that were established by RPC are removed from the list once they expire (reaching stop-time) or when they are terminated. Subscriptions that were established by configuration need to be deleted from the configuration by a configuration editing operation even if the stop time has been passed.</t>
</section>
<section title="Advertisement">
<t>Publishers supporting this document MUST indicate support the YANG model "ietf-subscribed-notifications" within the YANG library of the publisher. In addition support for optional features: "encode-xml", "encode-json", "configured" "supports-vrf", and "replay" MUST also be indicated if supported.</t>
<t>If a publisher supports this specification but not subscriptions via <xref target="RFC5277"/>, the publisher MUST NOT advertise "urn:ietf:params:netconf:capability:notification:1.0". Even without this advertisement however, the publisher MUST support the one-way notification element of <xref target="RFC5277"/> Section 4.</t>
</section>
</section>
<section title="YANG Data Model Trees">
<t>This section contains tree diagrams for top level YANG Data Node containers defined in <xref target="data_model"/>. If you would rather see tree diagrams for Notifications, see <xref target="state_notif"/>. Or for the tree diagrams for the RPCs, see <xref target="dynamic_subs"/>.</t>
<section title="Event Streams Container">
<t>A publisher maintains a list of available event streams as operational data. This list contains both standardized and vendor-specific event streams. The list of event streams that are supported by the publisher and against which subscription is allowed may be acquired from the "streams" container within the YANG module.</t>
<figure align="center" anchor="stream-tree"
title="Stream Container">
<artwork align="left"><![CDATA[
+--rw streams
+--rw stream* [name]
+--rw name stream
+--rw description string
+--rw replay-support? empty {replay}?
+--rw replay-log-creation-time? yang:date-and-time {replay}?
+--rw replay-log-aged-time? yang:date-and-time {replay}?
]]></artwork>
</figure>
</section>
<section title="Event Stream Filters Container">
<t>The "filters" container maintains a list of all subscription filters which persist outside the life-cycle of a single subscription. This enables pre-defined and validated filters which may be referenced and used by more than one subscription.</t>
<figure align="center" anchor="filter-tree"
title="Filter Container">
<artwork align="left"><![CDATA[
+--rw filters
+--rw stream-filter* [identifier]
+--rw identifier filter-id
+--rw (filter-spec)?
+--:(stream-subtree-filter)
| +--rw stream-subtree-filter? {subtree}?
+--:(stream-xpath-filter)
+--rw stream-xpath-filter? yang:xpath1.0 {xpath}?
]]></artwork>
</figure>
</section>
<section title="Subscriptions Container">
<t>The "subscriptions" container maintains a list of all subscriptions on a publisher, both configured and dynamic. It can be used to retrieve information about the subscriptions which a publisher is serving.</t>
<figure align="left">
<artwork align="left" xml:space="preserve"><![CDATA[
+--ro subscriptions
+--ro subscription* [identifier]
+--ro identifier subscription-id
+--ro configured-subscription-state? enumeration {configured}?
+--ro purpose? string {configured}?
+--ro protocol transport {configured}?
+--ro encoding encoding
+--ro (target)
| +--:(stream)
| +--ro (stream-filter)?
| | +--:(by-reference)
| | | +--ro stream-filter-ref stream-filter-ref
| | +--:(within-subscription)
| | +--ro (filter-spec)?
| | +--:(stream-subtree-filter)
| | | +--ro stream-subtree-filter? {subtree}?
| | +--:(stream-xpath-filter)
| | +--ro stream-xpath-filter?
| | yang:xpath1.0 {xpath}?
| +--ro stream? stream-ref
| +--ro replay-start-time? yang:date-and-time {replay}?
+--ro stop-time? yang:date-and-time
+--ro dscp? inet:dscp {qos}?
+--ro weighting? uint8 {qos}?
+--ro dependency? sn:subscription-id {qos}?
+--ro (notification-message-origin)?
| +--:(interface-originated)
| | +--ro source-interface? if:interface-ref
| +--:(address-originated)
| +--ro source-vrf? ->
| /ni:network-instances/network-instance/name {supports-vrf}?
| +--ro source-address? inet:ip-address-no-zone
+--ro receivers
+--ro receiver* [address port]
+--ro address inet:host
+--ro port inet:port-number
+--ro pushed-notifications? yang:counter64
+--ro excluded-notifications? yang:counter64
+--ro status enumeration
+---x reset
+--ro output
+--ro time yang:date-and-time
]]></artwork>
</figure>
</section>
<section title="Subscription-config Container">
<t>"Subscription-config" container contains the configuration of configured subscriptions.</t>
<figure align="left">
<artwork align="left" xml:space="preserve"><![CDATA[
+--rw subscription-config {configured}?
+--rw subscription* [identifier]
+--rw identifier subscription-id
+--rw purpose? string
+--rw protocol transport {configured}?
+--rw encoding encoding
+--rw (target)
| +--:(stream)
| +--rw (stream-filter)?
| | +--:(by-reference)
| | | +--rw stream-filter-ref stream-filter-ref
| | +--:(within-subscription)
| | +--rw (filter-spec)?
| | +--:(stream-subtree-filter)
| | | +--rw stream-subtree-filter? {subtree}?
| | +--:(stream-xpath-filter)
| | +--rw stream-xpath-filter? yang:xpath1.0 {xpath}?
| +--rw stream? stream-filter-ref
| +--rw replay-start-time? yang:date-and-time {replay}?
+--rw stop-time? yang:date-and-time
+--rw dscp? inet:dscp {qos}?
+--rw weighting? uint8 {qos}?
+--rw dependency? sn:subscription-id {qos}?
+--rw (notification-message-origin)?
| +--:(interface-originated)
| | +--rw source-interface? if:interface-ref
| +--:(address-originated)
| +--rw source-vrf? ->
| | /ni:network-instances/network-instance/name {supports-vrf}?
| +--rw source-address? inet:ip-address-no-zone
+--rw receivers
+--rw receiver* [address port]
+--rw address inet:host
+--rw port inet:port-number
]]></artwork>
</figure>
</section>
</section>
<section title="Data Model" anchor="data_model">
<figure>
<artwork align="left"><![CDATA[
<CODE BEGINS> file "ietf-subscribed-notifications.yang"
module ietf-subscribed-notifications {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications";
prefix sn;
import ietf-yang-types {
prefix yang;
}
import ietf-inet-types {
prefix inet;
}
import ietf-interfaces {
prefix if;
}
import ietf-network-instance {
prefix ni;
}
import ietf-restconf {
prefix rc;
}
organization "IETF";
contact
"WG Web: <http:/tools.ietf.org/wg/netconf/>
WG List: <mailto:[email protected]>
Editor: Alexander Clemm
<mailto:[email protected]>
Editor: Eric Voit
<mailto:[email protected]>
Editor: Alberto Gonzalez Prieto
<mailto:[email protected]>
Editor: Einar Nilsen-Nygaard
<mailto:[email protected]>
Editor: Ambika Prasad Tripathy
<mailto:[email protected]>";
description
"Contains a YANG specification for subscribing to event records
and receiving matching content within notification messages.";
revision 2018-01-24 {
description
"Initial version";
reference
"draft-ietf-netconf-subscribed-notifications-09";
}
/*
* FEATURES
*/
feature encode-json {
description
"This feature indicates that JSON encoding of notification
messages is supported.";
}
feature encode-xml {
description
"This feature indicates that XML encoding of notification
messages is supported.";
}
feature configured {
description
"This feature indicates that configuration of subscription is
supported.";
}
feature replay {
description
"This feature indicates that historical event record replay is
supported. With replay, it is possible for past event records to
be streamed in chronological order.";
}
feature xpath {
description
"This feature indicates support for xpath filtering.";
reference "http://www.w3.org/TR/1999/REC-xpath-19991116";
}
feature subtree {
description
"This feature indicates support for YANG subtree filtering.";
reference "RFC 6241, Section 6.";
}
feature supports-vrf {
description
"This feature indicates a publisher supports VRF configuration
for configured subscriptions. VRF support for dynamic
subscriptions does not require this feature.";
reference "draft-ietf-rtgwg-ni-model";
}
feature qos {
description
"This feature indicates a publisher supports one or more optional
Quality of Service (QoS) features to differentiate update record
treatment between publisher and receiver.";
}
/*
* EXTENSIONS
*/
extension subscription-state-notification {
description
"This statement applies only to notifications. It indicates that
the notification is a subscription state notification. Therefore
it does not participate in a regular event stream and does not
need to be specifically subscribed to in order to be received.
This statement can only occur as a substatement to the YANG
'notification' statement.";
}
/*
* IDENTITIES
*/
/* Identity for subscription success */
identity ok {
description
"OK - RPC was successful and was performed as requested.";
}
/* Identities for RPC and Notification errors */
identity establish-subscription-error {
description
"Problem found while attempting to fulfill an
'establish-subscription' rpc request. ";
}
identity modify-subscription-error {
description
"Problem found while attempting to fulfill a
'modify-subscription' rpc request. ";
}
identity delete-subscription-error {
description
"Problem found while attempting to fulfill either a
'delete-subscription' rpc request or a 'kill-subscription'
rpc request. ";
}
identity subscription-terminated-reason {
description
"Problem condition communicated to a receiver as part of absolute
'subscription-terminated' notification. ";
}
identity subscription-suspended-reason {
description
"Problem condition communicated to a receiver as part of absolute
'subscription-terminated' notification. ";
}
identity dscp-unavailable {
base establish-subscription-error;
description
"Requested DSCP marking not allocatable.";
}
identity filter-unavailable {
base subscription-terminated-reason;
description
"Referenced filter does not exist. This means a receiver is
referencing a filter which doesn't exist, or to which they do not
have access permissions.";
}
identity filter-unsupported {
base establish-subscription-error;
base modify-subscription-error;
description
"Cannot parse syntax within the filter. This failure can be from
a syntax error, or a syntax too complex to be processed by the
publisher.";
}
identity history-unavailable {
base establish-subscription-error;
description
"Replay request too far into the past. This means the publisher
does store historic information for the requested stream, but
not back to the requested timestamp.";
}
identity insufficient-resources {
base establish-subscription-error;
base modify-subscription-error;
description
"The publisher has insufficient resources to support the
requested subscription.";
}
identity no-such-subscription {
base modify-subscription-error;
base delete-subscription-error;
base subscription-terminated-reason;
description
"Referenced subscription doesn't exist. This may be as a result of
a non-existent subscription ID, an ID which belongs to another
subscriber, or an ID for configured subscription.";
}
identity replay-unsupported {
base establish-subscription-error;
description
"Replay cannot be performed for this subscription. This means the
publisher will not provide the requested historic information from
the stream via replay to this receiver.";
}
identity stream-unavailable {
base subscription-terminated-reason;
description
"Not a subscribable stream. This means the referenced stream is
not available for subscription by the receiver.";