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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-15) exists of draft-ietf-netmod-factory-default-14 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Netmod B. Lengyel 3 Internet-Draft Ericsson 4 Intended status: Standards Track B. Claise 5 Expires: September 18, 2020 Cisco Systems, Inc. 6 March 17, 2020 8 YANG Instance Data File Format 9 draft-ietf-netmod-yang-instance-file-format-09 11 Abstract 13 There is a need to document data defined in YANG models when a live 14 server is not available. Data is often needed already at design or 15 implementation time or needed by groups that do not have a live 16 running server available. This document specifies a standard file 17 format for YANG instance data, which follows the syntax and semantics 18 of existing YANG models, and annotates it with metadata. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on September 18, 2020. 37 Copyright Notice 39 Copyright (c) 2020 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (https://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 56 2.1. Principles . . . . . . . . . . . . . . . . . . . . . . . 4 57 2.2. Delivery of Instance Data . . . . . . . . . . . . . . . . 4 58 2.3. Data Life cycle . . . . . . . . . . . . . . . . . . . . . 5 59 3. Instance Data File Format . . . . . . . . . . . . . . . . . . 5 60 3.1. Specifying the Content Schema . . . . . . . . . . . . . . 7 61 3.1.1. Inline Method . . . . . . . . . . . . . . . . . . . . 7 62 3.1.2. Simplified-Inline Method . . . . . . . . . . . . . . 8 63 3.1.3. URI Method . . . . . . . . . . . . . . . . . . . . . 8 64 3.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 8 65 4. YANG Instance Data Model . . . . . . . . . . . . . . . . . . 12 66 4.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 12 67 4.2. YANG Model . . . . . . . . . . . . . . . . . . . . . . . 13 68 5. Security Considerations . . . . . . . . . . . . . . . . . . . 18 69 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 70 6.1. URI Registration . . . . . . . . . . . . . . . . . . . . 19 71 6.2. YANG Module Name Registration . . . . . . . . . . . . . . 19 72 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20 73 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 74 8.1. Normative References . . . . . . . . . . . . . . . . . . 20 75 8.2. Informative References . . . . . . . . . . . . . . . . . 21 76 Appendix A. Changes between revisions . . . . . . . . . . . . . 22 77 Appendix B. Backwards Compatibility . . . . . . . . . . . . . . 24 78 Appendix C. Detailed Use Cases - Non-Normative . . . . . . . . . 25 79 C.1. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 25 80 C.1.1. Use Case 1: Early Documentation of Server 81 Capabilities . . . . . . . . . . . . . . . . . . . . 25 82 C.1.2. Use Case 2: Preloading Data . . . . . . . . . . . . . 26 83 C.1.3. Use Case 3: Documenting Factory Default Settings . . 26 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 86 1. Terminology 88 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 89 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 90 "OPTIONAL" in this document are to be interpreted as described in BCP 91 14 [RFC2119] [RFC8174] when, and only when, they appear in all 92 capitals, as shown here. 94 Instance Data: A collection of instantiated data nodes. 96 Instance Data Set: A named set of data items annotated with metadata 97 that can be used as instance data in a YANG data tree. 99 Instance Data File: A file containing an instance data set formatted 100 according to the rules described in this document. 102 Content-schema: A set of YANG modules with their revision, supported 103 features, and deviations for which the instance data set contains 104 instance data. 106 Content defining YANG module: an individual YANG module that is part 107 of the content-schema. 109 The term Server is used as defined in [RFC8342]. 111 2. Introduction 113 There is a need to document data defined in YANG models when a live 114 server is not available. Data is often needed already at design or 115 implementation time or needed by groups that do not have a live 116 running server available. To facilitate this offline delivery of 117 data, this document specifies a standard format for YANG instance 118 data sets and YANG instance data files. 120 The following is a list of already implemented and potential use 121 cases. 123 UC1 Documentation of server capabilities 125 UC2 Preloading default configuration data 127 UC3 Documenting Factory Default Settings 129 UC4 Storing the configuration of a device, e.g., for backup, archive 130 or audit purposes 132 UC5 Storing diagnostics data 134 UC6 Allowing YANG instance data to potentially be carried within 135 other IPC message formats 137 UC7 Default instance data used as part of a templating solution 139 UC8 Providing data examples in RFCs or internet drafts 141 In Appendix C we describe the first three use cases in detail. 143 There are many and varied use cases where YANG instance data could be 144 used. We do not want to limit future uses of instance data sets, so 145 specifying how and when to use YANG instance data is out of scope for 146 this document. It is anticipated that other documents will define 147 specific use cases. Use cases are listed here only to indicate the 148 need for this work. 150 2.1. Principles 152 The following is a list of the basic principles of the instance data 153 format: 155 P1 Two standard formats shall be defined based on the XML and JSON 156 encodings. 158 P2 Instance data shall reuse existing encoding rules for YANG 159 defined data. 161 P3 Metadata about the instance data set (Section 3, Paragraph 9) 162 shall be defined. 164 P4 A YANG instance data set shall be allowed to contain data for 165 multiple YANG modules. 167 P5 Instance data shall be allowed to contain configuration data, 168 state data, or a mix of the two. 170 P6 Partial data sets shall be allowed. 172 P7 The YANG instance data format shall be usable for any data for 173 which YANG module(s) are defined and available to the reader, 174 independent of whether the module is actually implemented by a 175 server. 177 P8 It shall be possible to report the identity of the datastore with 178 which the instance data set is associated. 180 2.2. Delivery of Instance Data 182 Instance data sets that are produced as a result of some sort of 183 specification or design effort may be available without the need for 184 a live server e.g., via download from the vendor's website, or in any 185 other way that product documentation is distributed. 187 Other instance data sets may be read from or produced by the YANG 188 server itself e.g., UC5 documenting diagnostic data. 190 2.3. Data Life cycle 192 A YANG instance data set is created at a specific point of time. If 193 the data changes afterwards, this is not represented in the instance 194 data set anymore. The current values may be retrieved at run-time 195 via NETCONF/RESTCONF or received e.g., in YANG-Push notifications. 197 Whether the instance data changes and if so, when and how, should be 198 described either in the instance data set's description statement or 199 in some other implementation specific manner. 201 3. Instance Data File Format 203 A YANG instance data file MUST contain a single instance data set and 204 no additional data. 206 The format of the instance data set is defined by the ietf-yang- 207 instance-data YANG module. It is made up of a header part and 208 content-data. The header part carries metadata for the instance data 209 set. The content-data, defined as an anydata data node, carries the 210 instance data that we want to document/provide. The syntax and 211 semantics of content-data is defined by the content-schema. 213 Two formats are specified based on the XML and JSON YANG encodings. 214 Later as other YANG encodings (e.g., CBOR) are defined, further 215 instance data formats may be specified. 217 The content-data part MUST conform to the content-schema, while 218 allowing for the exceptions listed below. The content-data part 219 SHALL follow the encoding rules defined in [RFC7950] for XML and 220 [RFC7951] for JSON and MUST use UTF-8 character encoding. Content- 221 data MAY include: 223 metadata as defined by [RFC7952]. 225 a default attribute as defined in [RFC6243] section 6. and in 226 [RFC8040] section 4.8.9. 228 origin metadata as specified in [RFC8526] and [RFC8527] 230 implementation specific metadata relevant to individual data 231 nodes. Unknown metadata MUST be ignored by users of instance 232 data, allowing it to be used later for other purposes. 234 An instance data set MAY contain data for any number of YANG modules; 235 if needed it MAY carry the complete configuration and state data set 236 for a server. Default values SHOULD NOT be included. 238 Config=true and config=false data MAY be mixed in the instance data 239 file. 241 Instance data files MAY contain partial data sets. This means 242 mandatory, min-elements, require-instance=true, must and when 243 constrains MAY be violated. 245 The name of the instance data file SHOULD take one of the following 246 two forms: 248 If revision information inside the data set is present 250 * instance-data-set-name ['@' revision-date] '.filetype' 252 * E.g., acme-router-modules@2018-01-25.xml 254 If the leaf "name" is present in the instance data header, this 255 MUST be used. If the "revision-date" is present in both the 256 filename and in the instance data header, the revision date in the 257 file name MUST be set to the latest revision date inside the 258 instance data set. 260 If timestamp information inside the data set is present 262 * instance-data-set-name ['@' timestamp] '.filetype' 264 * E.g., acme-router-modules@2018-01-25T15_06_34_3+01_00.json 266 If the leaf "name" is present in the instance data header, this 267 MUST be used. If the "timestamp" is present both in the filename 268 and in the instance data header, the timestamp in the file name 269 MUST be set to the timestamp inside the instance data set; the 270 semicolons and the decimal point, if present, shall be replaced by 271 underscores. 273 The revision date or timestamp is optional. ".filetype" SHALL be 274 ".json" or ".xml" according to the format used. 276 Metadata, information about the data set itself SHOULD be included in 277 the instance data set. Some metadata items are defined in the YANG 278 module ietf-yang-instance-data, but other items MAY also be used. 279 Metadata MUST include: 281 Version of the YANG Instance Data format 283 Metadata SHOULD include: 285 o Name of the data set 286 o Content schema specification 288 o Description of the instance data set. The description SHOULD 289 contain information whether and how the data can change during the 290 lifetime of the server. 292 3.1. Specifying the Content Schema 294 To properly understand and use an instance data set, the user needs 295 to know the content-schema. One of the following methods SHOULD be 296 used: 298 Inline method: Include the needed information as part of the 299 instance data set. 301 Simplified-Inline method: Include the needed information as part 302 of the instance data set; short specification. 304 URI method: Include a URI that references another YANG instance 305 data file. This instance data file will use the same content- 306 schema as the referenced YANG instance data file. (if you don't 307 want to repeat the info again and again) 309 External Method: Do not include the content-schema, the user needs 310 to obtain the information through external documents. 312 Additional methods e.g., a YANG-package based solution may be added 313 later. 315 Note, the specified content-schema only indicates the set of modules 316 that were used to define this YANG instance data set. Sometimes 317 instance data may be used for a server supporting a different YANG 318 module set. (e.g., for "UC2 Preloading Data" the instance data set 319 may not be updated every time the YANG modules on the server are 320 updated) Whether an instance data set originally defined using a 321 specific content-schema is usable with a different other schema 322 depends on many factors including the amount of differences and the 323 compatibility between the original and the other schema, considering 324 modules, revisions, features, deviations, the scope of the instance 325 data, etc. 327 3.1.1. Inline Method 329 One or more inline-module elements define YANG module(s) used to 330 specify the content defining YANG modules. 332 E.g., ietf-yang-library@2016-06-21 334 The anydata inline-schema carries instance data (conforming to the 335 inline-modules) that actually specifies the content defining YANG 336 modules including revision, supported features, deviations and any 337 relevant additional data (e.g., revision labels 338 [I-D.verdt-netmod-yang-module-versioning]). See Section 3.2. 340 3.1.2. Simplified-Inline Method 342 The instance data set contains a list of content defining YANG 343 modules including the revision date for each. Usage of this method 344 implies that the modules are used without any deviations and with all 345 features supported. 347 3.1.3. URI Method 349 The same-schema-as-file leaf SHALL contain a URI that references 350 another YANG instance data file. The current instance data file will 351 use the same content schema as the referenced file. 353 The referenced instance data file MAY have no content-data if it is 354 used solely for specifying the content-schema. 356 If a referenced instance data file is not available, content-schema 357 is unknown. 359 The URI method is advantageous when the user wants to avoid the 360 overhead of specifying the content-schema in each instance data file: 361 E.g., In Use Case 6, when the system creates a diagnostic file every 362 minute to document the state of the server. 364 3.2. Examples 366 The following examples use artwork folding 367 [I-D.ietf-netmod-artwork-folding] for better formatting. 369 The following example is based on "UC1, Documenting Server 370 Capabilities". It provides (a shortened) list of supported YANG 371 modules and NETCONF capabilities for a server. It uses the inline 372 method to specify the content-schema. 374 ========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) =========== 376 377 379 acme-router-modules 380 2020-03-06 381 382 ietf-yang-library@2016-06-21 383 384 386 387 ietf-yang-library 388 2016-06-21 389 390 391 ietf-netconf-monitoring 392 2010-10-04 393 394 395 396 397 398 1956-10-23 399 Initial version 400 401 Defines the minimal set of modules that any \ 402 acme-router will contain. 403 info@acme.com 404 405 408 410 411 ietf-yang-library 412 2016-06-21 413 \ 414 urn:ietf:params:xml:ns:yang:ietf-yang-library\ 415 416 implement 417 418 419 ietf-system 420 2014-08-06 421 urn:ietf:params:xml:ns:yang:ietf-system 422 sys:authentication 423 sys:local-users 424 425 acme-system-ext 426 2018-08-06 427 428 implement 429 430 431 ietf-yang-types 432 2013-07-15 433 urn:ietf:params:xml:ns:yang:ietf-yang-types\ 434 435 import 436 437 438 acme-system-ext 439 2018-08-06 440 urn:rdns:acme.com:oammodel:acme-system-ext\ 441 442 implement 443 444 445 447 448 \ 449 urn:ietf:params:netconf:capability:validate:1.1\ 450 451 452 453 454 456 Figure 1: XML Instance Data Set - Use case 1, Documenting server 457 capabilities 459 The following example is based on "UC2, Preloading Default 460 Configuration". It provides a (shortened) default rule set for a 461 read-only operator role. It uses the inline method for specifying 462 the content-schema. 464 465 467 read-only-acm-rules 468 2020-03-06 469 470 ietf-yang-library@2019-01-04 471 472 474 475 all 476 477 ietf-netconf-acm 478 2012-02-22 479 480 481 482 483 484 485 1776-07-04 486 Initial version 487 488 Access control rules for a read-only role. 489 490 491 true 492 deny 493 deny 494 495 read-only-role 496 read-only-group 497 498 read-all 499 * 500 read 501 permit 502 503 504 505 506 508 Figure 2: XML Instance Data Set - Use case 2, Preloading access 509 control data 511 The following example is based on UC5 Storing diagnostics data. An 512 instance data set is produced by the server every 15 minutes that 513 contains statistics about NETCONF. As a new set is produced 514 periodically many times a day a revision-date would be useless; 515 instead a timestamp is included. 517 { 518 "ietf-yang-instance-data:instance-data-set": { 519 "name": "acme-router-netconf-diagnostics", 520 "format-version": "2020-03-06", 521 "content-schema": { 522 "same-schema-as-file": "file:///acme-diagnostics-schema.json", 523 }, 524 "timestamp": "2018-01-25T17:00:38Z", 525 "description": 526 "NETCONF statistics", 527 "content-data": { 528 "ietf-netconf-monitoring:netconf-state": { 529 "statistics": { 530 "netconf-start-time ": "2018-12-05T17:45:00Z", 531 "in-bad-hellos ": "32", 532 "in-sessions ": "397", 533 "dropped-sessions ": "87", 534 "in-rpcs ": "8711", 535 "in-bad-rpcs ": "408", 536 "out-rpc-errors ": "408", 537 "out-notifications": "39007" 538 } 539 } 540 } 541 } 542 } 544 Figure 3: JSON Instance Data File example - UC5 Storing diagnostics 545 data 547 4. YANG Instance Data Model 549 4.1. Tree Diagram 551 The following tree diagram [RFC8340] provides an overview of the data 552 model. 554 module: ietf-yang-instance-data 555 structure instance-data-set: 556 +--rw name? string 557 +--rw format-version string 558 +--rw content-schema 559 | +--rw (content-schema-spec)? 560 | +--:(simplified-inline) 561 | | +--rw module* string 562 | +--:(inline) {inline-content-schema}? 563 | | +--rw inline-module* string 564 | | +--rw inline-schema 565 | +--:(uri) 566 | +--rw same-schema-as-file? inet:uri 567 +--rw description* string 568 +--rw contact? string 569 +--rw organization? string 570 +--rw datastore? ds:datastore-ref 571 +--rw revision* [date] 572 | +--rw date string 573 | +--rw description? string 574 +--rw timestamp? yang:date-and-time 575 +--rw content-data? 577 4.2. YANG Model 579 This YANG module imports typedefs from [RFC6991], identities from 580 [RFC8342] and the "structure" extension from 581 [I-D.ietf-netmod-yang-data-ext]. 583 The YANG data model in this document conforms to the Network 584 Management Datastore Architecture (NMDA) defined in [RFC8342] 586 file "ietf-yang-instance-data@2020-03-06.yang" 587 module ietf-yang-instance-data { 588 yang-version 1.1; 589 namespace "urn:ietf:params:xml:ns:yang:ietf-yang-instance-data"; 590 prefix yid; 592 import ietf-yang-structure-ext { 593 prefix sx; 594 } 595 import ietf-datastores { 596 prefix ds; 597 } 598 import ietf-inet-types { 599 prefix inet; 600 } 601 import ietf-yang-types { 602 prefix yang; 603 } 605 organization 606 "IETF NETMOD Working Group"; 607 contact 608 "WG Web: 609 WG List: 611 Author: Balazs Lengyel 612 "; 613 description 614 "The module defines the structure and content of YANG 615 instance data sets. 617 The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 618 'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 619 'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document 620 are to be interpreted as described in BCP 14 (RFC 2119) 621 (RFC 8174) when, and only when, they appear in all 622 capitals, as shown here. 624 Copyright (c) 2020 IETF Trust and the persons identified as 625 authors of the code. All rights reserved. 627 Redistribution and use in source and binary forms, with or 628 without modification, is permitted pursuant to, and subject 629 to the license terms contained in, the Simplified BSD License 630 set forth in Section 4.c of the IETF Trust's Legal Provisions 631 Relating to IETF Documents 632 (http://trustee.ietf.org/license-info). 634 This version of this YANG module is part of RFC XXXX; see 635 the RFC itself for full legal notices."; 637 revision 2020-03-06 { 638 description 639 "Initial revision."; 640 reference 641 "RFC XXXX: YANG Instance Data Format"; 642 } 644 feature inline-content-schema { 645 description 646 "This feature indicates that inline content-schema 647 option is supported."; 648 } 649 sx:structure "instance-data-set" { 650 description 651 "A data structure to define a format for 652 YANG instance data sets. Consists of meta-data about 653 the instance data set and the real content-data."; 654 leaf name { 655 type string; 656 description 657 "Name of the YANG instance data set."; 658 } 659 leaf format-version { 660 type string; 661 default "2020-03-06"; 662 description 663 "Version of the 'YANG Instance Data format'. 665 It SHALL contain the revision date of the 666 ietf-yang-instance-data module used when creating the 667 instance data set in a YYYY-MM-DD format"; 668 } 669 container content-schema { 670 description 671 "The content schema used to create the instance data set"; 672 choice content-schema-spec { 673 description 674 "Specification of the content-schema"; 675 case simplified-inline { 676 leaf-list module { 677 type string; 678 description 679 "The list of content defining YANG modules. 681 The value SHALL start with the module name. 682 If the module contains a revision statement the 683 revision date SHALL be included in the leaf-list 684 entry. If other methods (e.g., revision-label) are 685 defined to identify individual module revisions 686 those MAY be used instead of using a revision date. 688 E.g., ietf-yang-library@2016-06-21 690 Usage of this leaf-list implies the modules are 691 used without any deviations and with all features 692 supported. Multiple revisions of the same module 693 MUST NOT be specified."; 694 } 695 } 696 case inline { 697 if-feature "inline-content-schema"; 698 leaf-list inline-module { 699 type string; 700 min-elements 1; 701 ordered-by user; 702 description 703 "Indicates that content defining YANG modules 704 are specified inline. 706 The value SHALL start with the module name. 707 If the module contains a revision statement the 708 revision date SHALL be included in the leaf-list 709 entry. If other methods (e.g., revision-label) are 710 defined to identify individual module revisions 711 those MAY be used instead of using a revision date. 713 E.g., ietf-yang-library@2016-06-21 715 The first item is either ietf-yang-library or some 716 other YANG module that contains a list of YANG modules 717 with their name, revision-date, supported-features, 718 and deviations. The usage of 719 ietf-yang-library@2019-01-04 MUST be supported. 720 Using other modules, module versions MAY also be 721 supported. 723 As some versions of ietf-yang-library MAY contain 724 different module-sets for different datastores, if 725 multiple module-sets are included, the instance data 726 set's meta-data MUST contain the datastore information 727 and instance data for the ietf-yang-library MUST also 728 contain information specifying the module-set for the 729 relevant datastore. 731 Subsequent items MAY specify YANG modules augmenting 732 the first module with useful data 733 (e.g., revision label)."; 734 } 735 anydata inline-schema { 736 mandatory true; 737 description 738 "Instance data corresponding to the YANG modules 739 specified in the inline-module nodes defining the set 740 of content defining YANG modules for this 741 instance-data-set."; 742 } 743 } 744 case uri { 745 leaf same-schema-as-file { 746 type inet:uri; 747 description 748 "A reference to another YANG instance data file. 749 This instance data file uses the same 750 content schema as the referenced file."; 751 } 752 } 753 } 754 } 755 leaf-list description { 756 type string; 757 description 758 "Description of the instance data set."; 759 } 760 leaf contact { 761 type string; 762 description 763 "Contact information for the person or 764 organization to whom queries concerning this 765 instance data set should be sent."; 766 } 767 leaf organization { 768 type string; 769 description 770 "Organization responsible for the instance 771 data set."; 772 } 773 leaf datastore { 774 type ds:datastore-ref; 775 description 776 "The identity of the datastore with which the 777 instance data set is associated, e.g., the datastore from 778 where the data was read or the datastore into which the data 779 may be loaded or the datastore which is being documented. 780 If a single specific datastore cannot be specified, the 781 leaf MUST be absent. 783 If this leaf is absent, then the datastore to which the 784 instance data belongs is undefined."; 785 } 786 list revision { 787 key "date"; 788 description 789 "Instance data sets that are produced as 790 a result of some sort of specification or design effort 791 SHOULD have at least one revision entry. For every 792 published editorial change, a new one SHOULD be added 793 in front of the revisions sequence so that all 794 revisions are in reverse chronological order. 796 For instance data sets that are read from 797 or produced by a server or otherwise 798 subject to frequent updates or changes, revision 799 SHOULD NOT be present"; 800 leaf date { 801 type string { 802 pattern '\d{4}-\d{2}-\d{2}'; 803 } 804 description 805 "Specifies the date the instance data set 806 was last modified. Formatted as YYYY-MM-DD"; 807 } 808 leaf description { 809 type string; 810 description 811 "Description of this revision of the instance data set."; 812 } 813 } 814 leaf timestamp { 815 type yang:date-and-time; 816 description 817 "The date and time when the instance data set 818 was last modified. 820 For instance data sets that are read from or produced 821 by a server or otherwise subject to frequent 822 updates or changes, timestamp SHOULD be present"; 823 } 824 anydata content-data { 825 description 826 "Contains the real instance data. 827 The data MUST conform to the relevant YANG Modules specified 828 either in the content-schema-spec or in some other 829 implementation specific manner."; 830 } 831 } 832 } 833 835 5. Security Considerations 837 The YANG module defined in this document is designed as a wrapper 838 specifying a format and a metadata header for YANG instance data 839 defined by the content-schema. The data is designed to be accessed 840 as a stored file or over any file access method or protocol. 842 The document does not specify any method to influence the behavior of 843 a server. 845 Instance data files may contain sensitive data. 847 The header part is not security sensitive. 849 The security sensitivity of the instance data in the content part is 850 completely dependent on the content schema. Depending on the nature 851 of the instance data, instance data files MAY need to be handled in a 852 secure way. The same kind of handling should be applied, that would 853 be needed for the result of a read operation returning the same data. 855 Instance data files should be protected against modification or 856 unauthorized access using normal file handling mechanisms. Care 857 should be taken, when copying the original files or providing file 858 access for additional users, not to reveal information 859 unintentionally. 861 6. IANA Considerations 863 This document registers one URI and one YANG module. 865 6.1. URI Registration 867 This document registers one URI in the IETF XML registry [RFC3688]. 868 Following the format in RFC 3688, the following registration is 869 requested to be made: 871 URI: urn:ietf:params:xml:ns:yang:ietf-yang-instance-data 873 Registrant Contact: The IESG. 875 XML: N/A, the requested URI is an XML namespace. 877 6.2. YANG Module Name Registration 879 This document registers one YANG module in the YANG Module Names 880 registry [RFC6020]. 882 name: ietf-yang-instance-data 883 namespace: urn:ietf:params:xml:ns:yang:ietf-yang-instance-data 884 prefix: yid 885 reference: RFC XXXX 887 7. Acknowledgments 889 For their valuable comments, discussions, and feedback, we wish to 890 acknowledge Andy Bierman, Juergen Schoenwaelder, Rob Wilton, Joe 891 Clarke, Kent Watsen Martin Bjorklund, Ladislav Lhotka, Qin Wu and 892 other members of the Netmod WG. 894 8. References 896 8.1. Normative References 898 [I-D.ietf-netmod-yang-data-ext] 899 Bierman, A., Bjorklund, M., and K. Watsen, "YANG Data 900 Structure Extensions", draft-ietf-netmod-yang-data-ext-05 901 (work in progress), December 2019. 903 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 904 Requirement Levels", BCP 14, RFC 2119, 905 DOI 10.17487/RFC2119, March 1997, 906 . 908 [RFC6243] Bierman, A. and B. Lengyel, "With-defaults Capability for 909 NETCONF", RFC 6243, DOI 10.17487/RFC6243, June 2011, 910 . 912 [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", 913 RFC 6991, DOI 10.17487/RFC6991, July 2013, 914 . 916 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", 917 RFC 7950, DOI 10.17487/RFC7950, August 2016, 918 . 920 [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", 921 RFC 7951, DOI 10.17487/RFC7951, August 2016, 922 . 924 [RFC7952] Lhotka, L., "Defining and Using Metadata with YANG", 925 RFC 7952, DOI 10.17487/RFC7952, August 2016, 926 . 928 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF 929 Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, 930 . 932 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 933 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 934 May 2017, . 936 [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", 937 BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, 938 . 940 [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., 941 and R. Wilton, "Network Management Datastore Architecture 942 (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, 943 . 945 [RFC8525] Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K., 946 and R. Wilton, "YANG Library", RFC 8525, 947 DOI 10.17487/RFC8525, March 2019, 948 . 950 [RFC8526] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., 951 and R. Wilton, "NETCONF Extensions to Support the Network 952 Management Datastore Architecture", RFC 8526, 953 DOI 10.17487/RFC8526, March 2019, 954 . 956 [RFC8527] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., 957 and R. Wilton, "RESTCONF Extensions to Support the Network 958 Management Datastore Architecture", RFC 8527, 959 DOI 10.17487/RFC8527, March 2019, 960 . 962 8.2. Informative References 964 [I-D.ietf-netmod-artwork-folding] 965 Watsen, K., Auerswald, E., Farrel, A., and Q. WU, 966 "Handling Long Lines in Inclusions in Internet-Drafts and 967 RFCs", draft-ietf-netmod-artwork-folding-12 (work in 968 progress), January 2020. 970 [I-D.ietf-netmod-factory-default] 971 WU, Q., Lengyel, B., and Y. Niu, "A YANG Data Model for 972 Factory Default Settings", draft-ietf-netmod-factory- 973 default-14 (work in progress), February 2020. 975 [I-D.verdt-netmod-yang-module-versioning] 976 Claise, B., Clarke, J., Rahman, R., Wilton, R., Lengyel, 977 B., Sterne, J., and K. D'Souza, "Updated YANG Module 978 Revision Handling", draft-verdt-netmod-yang-module- 979 versioning-01 (work in progress), October 2019. 981 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, 982 DOI 10.17487/RFC3688, January 2004, 983 . 985 [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for 986 the Network Configuration Protocol (NETCONF)", RFC 6020, 987 DOI 10.17487/RFC6020, October 2010, 988 . 990 [RFC8632] Vallin, S. and M. Bjorklund, "A YANG Data Model for Alarm 991 Management", RFC 8632, DOI 10.17487/RFC8632, September 992 2019, . 994 [RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications 995 for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, 996 September 2019, . 998 Appendix A. Changes between revisions 1000 Note to RFC Editor (To be removed by RFC Editor) 1002 v08 - v09 1004 o Removed reference to similar to get reply 1006 o Introduced artwork folding in the examples 1008 v07 - v08 1010 o Moved compatibility into appendix 1012 o Renamed yid-version to format-version as "yid" can be regarded as 1013 a racial slur. Changed format to date of the YANG module 1015 o Made support of ietf-yang-library mandatory if inline-content- 1016 schema is supported 1018 o Many small changes based on WGLC 1020 v06 - v07 1022 o Updated terminology, use-cases 1024 o Many small changes based on WGLC 1026 v05 - v06 1028 o Modified module name format, removed .yin or .yang extension 1030 o Removed pattern for module and inline-module. We want to allow 1031 the usage of revision-label later 1033 v04 - v05 1035 o Updated according to YANG-Doctor review 1037 o Updated security considerations 1039 o Added a wrapping container for the schema, and renamed the data 1040 nodes in the inline and uri cases. 1042 o Allowed .yin for simplified-inline schema naming. Made date 1043 optional if it is not available in the YANG module. 1045 o Added a mandatory yid-version to the header metadata to allow 1046 later updates of the module. 1048 v03 - v04 1050 o removed entity-tag and last-modified timestamp 1052 o Added simplified-inline method of content-schema specification 1054 v02 - v03 1056 o target renamed to "content-schema" and "content defining YANG 1057 module(s)" 1059 o Made name of instance data set optional 1061 o Updated according to draft-ietf-netmod-yang-data-ext-03 1063 o Clarified that entity-tag and last-modified timestamp are encoded 1064 as metadata. While they contain useful data, the HTTP-header 1065 based encoding from Restconf is not suitable. 1067 v01 - v02 1069 o Removed design time from terminology 1071 o Defined the format of the content-data part by referencing various 1072 RFCs and drafts instead of the result of the get-data and get 1073 operations. 1075 o Changed target-ptr to a choice 1077 o Inline target-ptr may include augmenting modules and alternatives 1078 to ietf-yang-library 1080 o Moved list of target modules into a separate 1081 element. 1083 o Added backwards compatibility considerations 1085 v00 - v01 1087 o Added the target-ptr metadata with 3 methods 1089 o Added timestamp metadata 1091 o Removed usage of dedicated .yid file extension 1093 o Added list of use cases 1095 o Added list of principles 1097 o Updated examples 1099 o Moved detailed use case descriptions to appendix 1101 Appendix B. Backwards Compatibility 1103 The concept of backwards compatibility and what changes are backwards 1104 compatible are not defined for instance data sets as it is highly 1105 dependent on the specific use case and the content-schema. 1107 For instance data that is the result of a design or specification 1108 activity, some changes that may be good to avoid are listed. YANG 1109 uses the concept of managed entities identified by key values; if the 1110 connection between the represented entity and the key value is not 1111 preserved during an update, this may lead to problems. 1113 o If the key value of a list entry that represents the same managed 1114 entity as before is changed, the user may mistakenly identify the 1115 list entry as new. 1117 o If the meaning of a list entry is changed, but the key values are 1118 not (e.g., redefining an alarm-type but not changing its alarm- 1119 type-id) the change may not be noticed. 1121 o If the key value of a previously removed list entry is reused for 1122 a different entity, the change may be misinterpreted as 1123 reintroducing the previous entity. 1125 Appendix C. Detailed Use Cases - Non-Normative 1127 C.1. Use Cases 1129 We present a number of use cases were YANG instance data is needed. 1131 C.1.1. Use Case 1: Early Documentation of Server Capabilities 1133 A server has a number of server-capabilities that are defined in YANG 1134 modules and can be retrieved from the server using protocols like 1135 NETCONF or RESTCONF. Server capabilities include: 1137 o data defined in ietf-yang-library: YANG modules, submodules, 1138 features, deviations, schema-mounts, and datastores supported 1139 ([RFC8525]) 1141 o alarms supported ([RFC8632]) 1143 o data nodes and subtrees that support or do not support on-change 1144 notifications ([RFC8641]) 1146 o netconf-capabilities in ietf-netconf-monitoring 1148 While it is good practice to allow a client to query these 1149 capabilities from the live server, that is often not possible. 1151 Often when a network node is released, an associated NMS (network 1152 management system) is also released with it. The NMS depends on the 1153 capabilities of the server. During NMS implementation, information 1154 about server capabilities is needed. If the information is not 1155 available early in some offline document, but only as instance data 1156 from the live network node, the NMS implementation will be delayed, 1157 because it has to wait until the network node is ready. Also 1158 assuming that all NMS implementors will have a correctly configured 1159 network nodes from which data can be retrieved, is a very expensive 1160 proposition. (An NMS may handle dozens of node types.) 1162 Network operators often build their own home-grown NMS systems that 1163 need to be integrated with a vendor's network node. The operator 1164 needs to know the network node's server capabilities in order to do 1165 this. Moreover, the network operator's decision to buy a vendor's 1166 product may even be influenced by the network node's OAM feature set 1167 documented as the server's capabilities. 1169 Beside NMS implementors, system integrators and many others also need 1170 the same information early. Examples could be model driven testing, 1171 generating documentation, etc. 1173 Most server-capabilities are relatively stable and change only during 1174 upgrade or due to licensing or the addition or removal of hardware. 1175 They are usually defined by a vendor at design time, before the 1176 product is released. It is feasible and advantageous to define/ 1177 document them early e.g., in a YANG instance data File. 1179 It is anticipated that a separate IETF document will define in detail 1180 how and which set of server capabilities should be documented. 1182 C.1.2. Use Case 2: Preloading Data 1184 There are parts of the configuration that must be fully configurable 1185 by the operator. However, often a simple default configuration will 1186 be sufficient. 1188 One example is access control groups/roles and related rules. While 1189 a sophisticated operator may define dozens of different groups, often 1190 a basic (read-only operator, read-write system administrator, 1191 security-administrator) triplet will be enough. Vendors will often 1192 provide such default configuration data to make device configuration 1193 easier for an operator. 1195 Defining access control data is a complex task. To help, the device 1196 vendor predefines a set of default groups (/nacm:nacm/groups) and 1197 rules for these groups to access specific parts of common models 1198 (/nacm:nacm/rule-list/rule). 1200 YANG instance data files are used to document and/or preload the 1201 default configuration. 1203 C.1.3. Use Case 3: Documenting Factory Default Settings 1205 Nearly every server has a factory default configuration. If the 1206 system is really badly misconfigured or if the current configuration 1207 is to be abandoned, the system can be reset the default factory 1208 configuration. 1210 In NETCONF, the operation can already be used to 1211 reset the startup datastore. There are ongoing efforts to introduce 1212 a new, more generic factory-reset operation for the same purpose 1213 [I-D.ietf-netmod-factory-default] 1215 The operator currently has no way to know what the default 1216 configuration actually contains. YANG instance data can also be used 1217 to document the factory default configuration. 1219 Authors' Addresses 1220 Balazs Lengyel 1221 Ericsson 1222 Magyar Tudosok korutja 11 1223 1117 Budapest 1224 Hungary 1226 Phone: +36-70-330-7909 1227 Email: balazs.lengyel@ericsson.com 1229 Benoit Claise 1230 Cisco Systems, Inc. 1231 De Kleetlaan 6a b1 1232 1831 Diegem 1233 Belgium 1235 Phone: +32 2 704 5622 1236 Email: bclaise@cisco.com