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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446) ** Obsolete normative reference: RFC 6536 (Obsoleted by RFC 8341) == Outdated reference: A later version (-15) exists of draft-ietf-netconf-https-notif-01 Summary: 2 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NETCONF T. Zhou 3 Internet-Draft G. Zheng 4 Intended status: Standards Track Huawei 5 Expires: September 10, 2020 E. Voit 6 Cisco Systems 7 A. Clemm 8 Futurewai 9 T. Graf 10 Swisscom 11 P. Francois 12 INSA-Lyon 13 March 9, 2020 15 Subscription to Multiple Stream Originators 16 draft-unyte-netconf-multi-stream-originators-00 18 Abstract 20 This document describes the distributed data export mechanism that 21 allows multiple data streams to be managed by using a single 22 subscription. Specifically, device can decide to decompse one 23 subscription into multiple subscriptions to the line-cards. So that 24 each line-card can directly push data to the collector without 25 passing through a broker for internal consolidation. And the device 26 can indicate the subscription decomposition result to the receiver to 27 check the data integrity. 29 Requirements Language 31 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 32 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 33 document are to be interpreted as described in RFC 2119 [RFC2119]. 35 Status of This Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at https://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on September 10, 2020. 51 Copyright Notice 53 Copyright (c) 2020 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (https://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 69 2. Data Collection from Devices with Main-board and Line-cards . 3 70 3. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 4 71 4. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 5 72 5. Subscription Decomposition . . . . . . . . . . . . . . . . . 7 73 6. Publication Composition . . . . . . . . . . . . . . . . . . . 8 74 7. Subscription State Change Notifications . . . . . . . . . . . 9 75 8. Publisher Configurations . . . . . . . . . . . . . . . . . . 9 76 9. YANG Tree . . . . . . . . . . . . . . . . . . . . . . . . . . 9 77 10. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . . 10 78 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 79 12. Transport Considerations . . . . . . . . . . . . . . . . . . 12 80 13. Security Considerations . . . . . . . . . . . . . . . . . . . 12 81 14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 82 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 83 15.1. Normative References . . . . . . . . . . . . . . . . . . 13 84 15.2. Informative References . . . . . . . . . . . . . . . . . 14 85 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 15 86 A.1. Dynamic Subscription . . . . . . . . . . . . . . . . . . 15 87 A.2. Configured Subscription . . . . . . . . . . . . . . . . . 18 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 90 1. Introduction 92 Streaming telemetry refers to sending a continuous stream of 93 operational data from a device to a remote receiver. This provides 94 an ability to monitor a network from remote and to provide network 95 analytics. Devices generate telemetry data and push that data to a 96 collector for further analysis. By streaming the data, much better 97 performance, finer-grained sampling, monitoring accuracy, and 98 bandwidth utilization can be achieved than with polling-based 99 alternatives. 101 Mechanisms to support subscription to event notifications have been 102 defined in[RFC8639] and [RFC8641]. The current design involves 103 subscription to a single push server. This conceptually centralized 104 model encounters efficiency limitations in cases where the data 105 sources are themselves distributed, such as line cards in a piece of 106 network equipment. In such cases, it will be a lot more efficient to 107 have each data source (e.g., each line card) originate its own stream 108 of updates, rather than requiring updates to be tunneled through a 109 central server where they are combined. What is needed is a 110 distributed mechanism that allows to directly push multiple 111 individual data substreams, without needing to first pass them 112 through an additional processing stage for internal consolidation, 113 but still allowing those substreams to be managed and controlled via 114 a single subscription. 116 This document will describe such distributed data export mechanism 117 and how it can work by extending existing push mechanism. 118 Specifically, device can decide to decompse one subscription into 119 multiple subscriptions to the line-cards. So that each line-card can 120 directly push data to the collector without passing through a broker 121 for internal consolidation. And the device can indicate the 122 subscription decomposition result to the receiver to check the data 123 integrity. The proposal will focus on the scenario when data 124 collection from devices with main-board and line-cards. It could be 125 generalized to other distributed data export scenarios. 127 2. Data Collection from Devices with Main-board and Line-cards 129 For data collection from devices with main-board and line-cards, 130 existing push solutions consider only one push server typically 131 reside in the main board. As shown in the following figure, data are 132 collected from line cards and aggregate to the main board as one 133 consolidated stream. So the main board can easily become the 134 performance bottle-neck. The optimization is to apply the 135 distributed data export mechanism which can directly push data from 136 line cards to a collector. On one hand, this will reduce the cost of 137 scarce compute and memory resources on the main board for data 138 processing and assembling. On the other hand, distributed data push 139 can off-load the streaming traffic to multiple interfaces. 141 +-------------------------------------+ 142 | collector | 143 +------^-----------^-----------^------+ 144 | | | 145 | | | 146 +-------------------------------------+ 147 | | | | | 148 | | +-----+------+ | | 149 | | | main board | | | 150 | | +--^-----^---+ | | 151 | | | | | | 152 | | +---+ +---+ | | 153 | | | | | | 154 | +----+----+---+ +---+----+----+ | 155 | | line card 1 | | line card 2 | | 156 | +-------------+ +-------------+ | 157 | device | 158 +-------------------------------------+ 160 Fig. 1 Data Collection from Devices with Main-board and Line-cards 162 3. Terminologies 164 The following terms are defined in [RFC8639] and are not redefined 165 here: 167 Subscriber 169 Publisher 171 Receiver 173 Subscription 175 In addition, this document defines the following terms: 177 Global Subscription: the Subscription requested by the subscriber. 178 It may be decomposed into multiple Component Subscriptions. 180 Component Subscription: is the Subscription that defines the data 181 from each individual telemetry source which is managed and controlled 182 by a single Publisher. 184 Global Capability: is the overall subscription capability that the 185 group of Publishers can expose to the Subscriber. 187 Component Capability: is the subscription capability that each 188 Publisher can expose to the Subscriber. 190 Master: is the Publisher that interacts with the Subscriber to deal 191 with the Global Subscription. It decomposes the Global Subscription 192 to multiple Component Subscriptions and interacts with the Agents. 194 Agent: is the Publisher that interacts with the Master to deal with 195 the Component Subscription. 197 4. Solution Overview 199 Figure 2 below shows the distributed data export framework. 201 A collector usually includes two components, 203 o the Subscriber generates the subscription instructions to express 204 what and how the collector want to receive the data; 206 o the Receiver is the target for the data publication. 208 For one subscription, there may be one to many Receivers. And the 209 Subscriber does not necessarily share the same address with the 210 Receivers. 212 In this framework, the Publisher pushes data to the Receiver 213 according to the subscription information. The Publisher has the 214 Master role and the Agent role. The Master knows all the 215 capabilities that the attached Agents and itself can provide, and 216 exposes the Global Capability to the collector. The collector cannot 217 see the Agents directly, so it will only send the Global Subscription 218 information to the Master. The Master disassembles the Global 219 Subscription to multiple Component Subscriptions, each involving data 220 from a separate telemetry source. The Component Subscriptions are 221 then distributed to the corresponding Agents. 223 When data streaming, the Publisher collects and encapsulates the 224 packets per the Component Subscription, and pushes the piece of data 225 which can serve directly to the designated data collector. The 226 collector is able to assemble many pieces of data associated with one 227 Global Subscription, and can also deduce the missing pieces of data. 229 +-----------------------------------------+ 230 | Collector |-------------+ | 231 | +------------+ | | 232 | +------------+ || Receiver | | | 233 | | Subscriber | |--------------+ | 234 | +-----^-+----+ +-----^------^ | 235 | | | | | | 236 +-----------------------------------------+ 237 Global | | Global | | 238 Capability| | Subscription | | 239 +-----------------------------------------+ 240 | | | Push | | | 241 | +--------+-v---------------+---+ | | 242 | | Publisher(Master) | | | 243 | +--------^-+-------------------+ | | 244 | | | | | 245 | | | | | 246 | Component | | Component Push | | 247 | Capability| | Subscription | | 248 | +--------+-v-------------------+ | | 249 | | Publisher(Agent) +--+ | 250 | +------------------------------+ | 251 | | 252 | Device | 253 +-----------------------------------------+ 255 Fig. 2 The Distributed Data Export Framework 257 Master and Agents may interact with each other in several ways: 259 o Agents need to have a registration or announcement handshake with 260 the Master, so the Master is aware of them and of life-cycle 261 events (such as Agent appearing and disappearing). 263 o Contracts are needed between the Master and each Agent on the 264 Component Capability, and the format for streaming data structure. 266 o The Master relays the component subscriptions to the Agents. 268 o The Agents indicate status of Component Subscriptions to the 269 Master. The status of the overall subscription is maintained by 270 the Master. The Master is also responsible for notifying the 271 subscriber in case of any problems of Component Subscriptions. 273 Any technical mechanisms or protocols used for the coordination of 274 operational information between Master and Agent is out-of-scope of 275 this document. We will need to instrument the results of this 276 coordination on the Master. 278 5. Subscription Decomposition 280 The Collector can only subscribe to the Master. This requires the 281 Master to: 283 1. expose the Global Capability that can be served by multiple 284 Publishers; 286 2. disassemble the Global Subscription to multiple Component 287 Subscriptions, and distribute them to the corresponding telemetry 288 sources; 290 3. notify on changes when portions of a subscription moving between 291 different Agents over time. 293 The Master can keep track of the mapping between the resource and the 294 corresponding location of the Publisher which commits to serve the 295 data. If a Publisher does not have external connectivity or 296 permission to export, the master MUST NOT decompose a component 297 subscription to that Publisher. In some implementations, the Global 298 Subscription can be disassembled into multiple Component 299 Subscriptions according to the Resource-Location Table, and the 300 corresponding location can be associated. The decision whether to 301 decompose a Global Subscription into multiple Component Subscriptions 302 rests with the Resource-Location Table. A Master can decide to not 303 decompose a Global Subscription at all and push a single stream to 304 the receiver, because the location information indicates the Global 305 Subscription can be served locally by the Master. Similarly, it can 306 decide to entirely decompose a Global Subscription into multiple 307 Component Subscriptions that each push their own streams, but not 308 from the Master. It can also decide to decompose the Global 309 Subscription into several Component Subscriptions and retain some 310 aspects of the Global Subscription itself, also pushing its own 311 stream. 313 Component Subscriptions belonging to the same Global Subscription 314 MUST NOT overlap. The combination of all Component Subscriptions 315 MUST cover the same range of nodes as the Global Subscription. Also, 316 the same subscription settings apply to each Component Subscription, 317 i.e., the same receivers, the same time periods, the same encodings 318 are applied to each Component Subscription per the settings of the 319 Global Subscription. 321 Each Component Subscription in effect constitutes a full-fledged 322 subscription, with the following constraints: 324 o Component subscriptions are system-controlled, i.e. managed by the 325 Master, not by the subscriber. 327 o Component subscription settings such as time periods, dampening 328 periods, encodings, receivers adopt the settings of their Global 329 Subscription. 331 o The life-cycle of the Component Subscription is tied to the life- 332 cycle of the Global Subscription. Specifically, terminating/ 333 removing the Global Subscription results in termination/removal of 334 Component Subscriptions. 336 o The Component Subscriptions share the same Subscription ID as the 337 Global Subscription. 339 6. Publication Composition 341 The Publisher collects data and encapsulates the packets per the 342 Component Subscription. There are several potential encodings, 343 including XML, JSON, CBOR and GPB. The format and structure of the 344 data records are defined by the YANG schema, so that the composition 345 at the Receiver can benefit from the structured and hierarchical data 346 instance. 348 The Receiver is able to assemble many pieces of data associated with 349 one subscription, and can also deduce the missing pieces of data. 350 The Receiver recognizes data records associated with one subscription 351 according the Subscription ID [RFC8639]. Data records generated per 352 one subscription are assigned with the same Subscription ID. 354 For the periodic updates, records are produced periodically from each 355 Publisher. The message arrival time varies because of the 356 distributed nature of the publication. The Receiver assembles data 357 generated at the same time period based on the recording time 358 consisted in each data record. In this case, time synchronization is 359 required for all the Publishers. 361 Message Generator ID [I-D.ietf-netconf-notification-messages] is the 362 identifier for the process which created the notification message. 363 It's contained in every notification messages, and allows 364 disambiguation of different line cards sending the messages. This 365 document, in addition, requires the device to notify collector the 366 set of Message Generator IDs standing for the Publishers serving for 367 one Global Subscription. So that the collector can easily check the 368 integrity of the data collected from different Publishers at the same 369 time period. And the collector can deduce the Publishers which are 370 responsible for the missing pieces of data. 372 For the dynamic subscription, the output of the "establish- 373 subscription" RPC defined in [RFC8639] MUST include a list of Message 374 Generator IDs to indicate how the Global Subscription is decomposed 375 into several Component Subscriptions. 377 The "subscription-started" and "subscription-modified" notification 378 defined in [RFC8639] MUST also include a list of Message Generator 379 IDs to notify the current Publishers for the corresponding Global 380 Subscription. 382 7. Subscription State Change Notifications 384 In addition to sending event records to receivers, the Master MUST 385 also send subscription state change notifications [RFC8639] when 386 events related to subscription management have occurred. All the 387 subscription state change notifications MUST be delivered by the 388 Master. 390 When the subscription decomposition result changed, the 391 "subscription-modified" notification MUST be sent to indicate the new 392 list of Publishers. 394 8. Publisher Configurations 396 This document assumes all the Publishers are preconfigured to be able 397 to push data. The actual working Publishers are selected dynamically 398 based on the subscription decomposition result. For UDP Publishers, 399 the virtual IP address could be assigned for the publication. So all 400 the UDP Publishers on the device can use the same source IP address 401 configured, which may even not routeable. For connection based 402 Publishers, e.g., HTTPS-based transport 403 [I-D.ietf-netconf-https-notif], each Publisher MUST be able to 404 receive packets from the receivers. This document does not restrict 405 the way how the Publishers are accessible. 407 The specific configuration on transports is out of the scope of this 408 document. 410 9. YANG Tree 411 module: ietf-multiple-stream-originators 412 augment /sn:subscriptions/sn:subscription: 413 +--ro message-generator-id* string 414 augment /sn:subscription-started: 415 +--ro message-generator-id* string 416 augment /sn:subscription-modified: 417 +--ro message-generator-id* string 418 augment /sn:establish-subscription/sn:output: 419 +--ro message-generator-id* string 421 10. YANG Module 423 file "ietf-multiple-stream-originators@2020-02-26.yang" 424 module ietf-multiple-stream-originators { 425 yang-version 1.1; 426 namespace 427 "urn:ietf:params:xml:ns:yang:ietf-multiple-stream-originators"; 428 prefix mso; 429 import ietf-subscribed-notifications { 430 prefix sn; 431 } 433 organization "IETF NETCONF (Network Configuration) Working Group"; 434 contact 435 "WG Web: 436 WG List: 438 Editor: Tianran Zhou 439 441 Editor: Guangying Zheng 442 "; 444 description 445 "Defines augmentation for ietf-subscribed-notifications to enable 446 the distributed publication with single subscription. 448 Copyright (c) 2018 IETF Trust and the persons identified as authors 449 of the code. All rights reserved. 451 Redistribution and use in source and binary forms, with or without 452 modification, is permitted pursuant to, and subject to the license 453 terms contained in, the Simplified BSD License set forth in Section 454 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents 455 (https://trustee.ietf.org/license-info). 457 This version of this YANG module is part of RFC XXXX; see the RFC 458 itself for full legal notices."; 460 revision 2020-02-26 { 461 description 462 "Initial version"; 463 reference 464 "RFC XXXX: Subscription to Multiple Stream Originators"; 465 } 467 grouping message-generator-ids { 468 description 469 "Provides a reusable list of message-generator-ids."; 471 leaf-list message-generator-id { 472 type string; 473 config false; 474 ordered-by user; 475 description 476 "Software entity which created the message (e.g., 477 linecard 1). This field is used to notify the 478 collector the working originator."; 479 } 480 } 482 augment "/sn:subscriptions/sn:subscription" { 483 description 484 "This augmentation allows the message generators to be exposed 485 for a subscription."; 487 uses message-generator-ids; 488 } 490 augment "/sn:subscription-started" { 491 description 492 "This augmentation allows MSO specific parameters to be 493 exposed for a subscription."; 495 uses message-generator-ids; 496 } 498 augment "/sn:subscription-modified" { 499 description 500 "This augmentation allows MSO specific parameters to be 501 exposed for a subscription."; 503 uses message-generator-ids; 504 } 505 augment "/sn:establish-subscription/sn:output" { 506 description 507 "This augmentation allows MSO specific parameters to be 508 exposed for a subscription."; 510 uses message-generator-ids; 511 } 512 } 513 515 11. IANA Considerations 517 This document registers the following namespace URI in the IETF XML 518 Registry [RFC3688]: 520 URI: urn:ietf:params:xml:ns:yang:ietf-multiple-stream-originators 522 Registrant Contact: The IESG. 524 XML: N/A; the requested URI is an XML namespace. 526 This document registers the following YANG module in the YANG Module 527 Names registry [RFC3688]: 529 Name: ietf-multiple-stream-originators 531 Namespace: urn:ietf:params:xml:ns:yang:ietf-multiple-stream- 532 originators 534 Prefix: mso 536 Reference: RFC XXXX 538 12. Transport Considerations 540 The distributed data export mechanism enabled by this draft is 541 expected to generate more data than YANG-Push [RFC8641]. The large 542 amount of data may congest the network and impact other network 543 business. In this case, the collector may also not be able to accept 544 all the data. So the congestion control method is required for any 545 transport that is going to implement the solution proposed in this 546 document. 548 13. Security Considerations 550 The YANG module specified in this document defines a schema for data 551 that is designed to be accessed via network management protocols such 552 as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer 553 is the secure transport layer, and the mandatory-to-implement secure 554 transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer 555 is HTTPS, and the mandatory-to-implement secure transport is TLS 556 [RFC5246]. 558 The NETCONF Access Control Model (NACM) [RFC6536] provides the means 559 to restrict access for particular NETCONF or RESTCONF users to a 560 preconfigured subset of all available NETCONF or RESTCONF protocol 561 operations and content. 563 The new data nodes introduced in this YANG module may be considered 564 sensitive or vulnerable in some network environments. It is thus 565 important to control read access (e.g., via get-config or 566 notification) to this data nodes. These are the subtrees and data 567 nodes and their sensitivity/vulnerability: 569 o /subscriptions/subscription/message-generator-ids 571 The entries in the two lists above will show where subscribed 572 resources might be located on the publishers. Access control MUST be 573 set so that only someone with proper access permissions has the 574 ability to access this resource. 576 Other Security Considerations is the same as those discussed in YANG- 577 Push [RFC8641]. 579 14. Acknowledgements 581 We thank Kent Watsen, Mahesh Jethanandani, Martin Bjorklund, Tim 582 Carey and Qin Wu for their constructive suggestions for improving 583 this document. 585 15. References 587 15.1. Normative References 589 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 590 Requirement Levels", BCP 14, RFC 2119, 591 DOI 10.17487/RFC2119, March 1997, 592 . 594 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, 595 DOI 10.17487/RFC3688, January 2004, 596 . 598 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 599 (TLS) Protocol Version 1.2", RFC 5246, 600 DOI 10.17487/RFC5246, August 2008, 601 . 603 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., 604 and A. Bierman, Ed., "Network Configuration Protocol 605 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, 606 . 608 [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure 609 Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, 610 . 612 [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration 613 Protocol (NETCONF) Access Control Model", RFC 6536, 614 DOI 10.17487/RFC6536, March 2012, 615 . 617 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF 618 Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, 619 . 621 [RFC8639] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard, 622 E., and A. Tripathy, "Subscription to YANG Notifications", 623 RFC 8639, DOI 10.17487/RFC8639, September 2019, 624 . 626 [RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications 627 for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, 628 September 2019, . 630 15.2. Informative References 632 [I-D.ietf-netconf-https-notif] 633 Jethanandani, M. and K. Watsen, "An HTTPS-based Transport 634 for Configured Subscriptions", draft-ietf-netconf-https- 635 notif-01 (work in progress), October 2019. 637 [I-D.ietf-netconf-notification-messages] 638 Voit, E., Jenkins, T., Birkholz, H., Bierman, A., and A. 639 Clemm, "Notification Message Headers and Bundles", draft- 640 ietf-netconf-notification-messages-08 (work in progress), 641 November 2019. 643 Appendix A. Examples 645 This appendix is non-normative. 647 A.1. Dynamic Subscription 649 Figure 3 shows a typical dynamic subscription to the device with 650 distributed data export capability. 652 +-------------+ +-------------+ +-------------+ 653 | Subscriber/ | | Publisher | | Publisher | 654 | Receiver | | (Master) | | (Agent) | 655 +-------------+ +------+------+ +------+------+ 656 | | | 657 | establish-subscription | | 658 +------------------------------>+ component | 659 | | subscription | 660 | RPC Reply: OK, id #22 +-------------->+ 661 | message generator ID [#1, #2] | | 662 +<------------------------------+ | 663 | | | 664 | notif-mesg, id #22 | | 665 | message generator ID #1 | | 666 +<------------------------------+ | 667 | | | 668 | notif-mesg, id#22 | | 669 | message generator ID #2 | | 670 +<----------------------------------------------+ 671 | | | 672 | modify-subscription (id#22) | | 673 +------------------------------>+ component | 674 | | subscription | 675 | RPC Reply: OK, id #22 +-------------->+ 676 +<------------------------------+ | 677 | | | 678 | subscription-modified, id#22 | | 679 | message generator ID [#1] | | 680 +<------------------------------+ | 681 | | | 682 | notif-mesg, id #22 | | 683 | message generator ID #1 | | 684 +<------------------------------+ | 685 | | | 686 | | | 687 + + + 689 Fig. 3 Call Flow for Dynamic Subscription 691 A "establish-subscription" RPC request as per [RFC8641] is sent to 692 the Master with a successful response. An example of using NETCONF 693 might look like: 695 697 700 702 ds:operational 703 704 706 /ex:foo 707 708 709 500 710 711 712 714 Fig. 4 "establish-subscription" Request 716 As the device is able to fully satisfy the request, the request is 717 given a subscription ID of 22. The response as in Figure 5 indicates 718 that the subscription is decomposed into two component subscriptions 719 which will be published by two message generators: #1 and #2. 721 723 725 22 726 727 733 2 734 735 737 Fig. 5 "establish-subscription" Positive RPC Response 739 Then, both Publishers send notifications with the corresponding piece 740 of data to the receiver. 742 The subscriber may invoke the "modify-subscription" RPC for a 743 subscription it previously established. The RPC has no difference to 744 the single publisher case as in [RFC8641]. Figure 6 provides an 745 example where a subscriber attempts to modify the period and 746 datastore XPath filter of a subscription using NETCONF. 748 750 754 22 755 757 ds:operational 758 759 761 /ex:bar 762 763 764 250 765 766 767 769 Fig. 6 "modify-subscription" Request 771 If the modification is successfully accepted, the "subscription- 772 modified" subscription state notification is sent to the subscriber 773 by the Master. The notification, Figure 7 for example, indicates the 774 modified subscription is decomposed into one component subscription 775 which will be published by message generator #1. 777 778 2007-09-01T10:00:00Z 779 782 22 783 785 ds:operational 786 787 789 /ex:bar 790 791 792 250 793 794 838 2007-09-01T10:00:00Z 839 842 39 843 845 ds:operational 846 847 849 /ex:foo 850 851 852 250 853 854 860 2 861 862 863 865 Fig. 9 "subscription-started" Subscription State Notification 867 Then, both Publishers send notifications with the corresponding piece 868 of data to the receiver. 870 Authors' Addresses 872 Tianran Zhou 873 Huawei 874 156 Beiqing Rd., Haidian District 875 Beijing 876 China 878 Email: zhoutianran@huawei.com 879 Guangying Zheng 880 Huawei 881 101 Yu-Hua-Tai Software Road 882 Nanjing, Jiangsu 883 China 885 Email: zhengguangying@huawei.com 887 Eric Voit 888 Cisco Systems 889 United States of America 891 Email: evoit@cisco.com 893 Alexander Clemm 894 Futurewai 895 2330 Central Expressway 896 Santa Clara, California 897 United States of America 899 Email: ludwig@clemm.org 901 Thomas Graf 902 Swisscom 903 Binzring 17 904 Zuerich 8045 905 Switzerland 907 Email: thomas.graf@swisscom.com 909 Pierre Francois 910 INSA-Lyon 911 Lyon 912 France 914 Email: pierre.francois@insa-lyon.fr