NETMOD Working Group K. Watsen Internet-Draft Watsen Networks Intended status: Standards Track 17 May 2024 Expires: 18 November 2024 XML Encoding of Data Modeled with YANG draft-yn-netmod-yang-xml-00 Abstract This document defines encoding rules for representing YANG modeled configuration data, state data, parameters of Remote Procedure Call (RPC) operations or actions, and notifications defined using XML. GitHub Information (to be removed by RFC Editor) This document is developed on GitHub (https://github.com/netmod-wg/ rfc7950bis). If you wish to contribute, please consider opening a pull request (PR). Please see the README (https://github.com/netmod- wg/rfc7950bis/blob/main/README.md) file for details. Special Thanks The following individuals were entrusted to review all of the design proposals and specification updates made by authors. Sorted by first name: Kent Watsen. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 18 November 2024. Watsen Expires 18 November 2024 [Page 1] Internet-Draft XML Encoding of YANG Data May 2024 Copyright Notice Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology and Notation . . . . . . . . . . . . . . . . . . 3 3. Properties of the XML Encoding . . . . . . . . . . . . . . . 4 4. Names and Namespaces . . . . . . . . . . . . . . . . . . . . 4 5. Encoding of YANG Data Node Instances . . . . . . . . . . . . 6 5.1. The "leaf" Data Node . . . . . . . . . . . . . . . . . . 6 5.2. The "container" Data Node . . . . . . . . . . . . . . . . 6 5.3. The "leaf-list" Data Node . . . . . . . . . . . . . . . . 6 5.4. The "list" Data Node . . . . . . . . . . . . . . . . . . 7 5.5. The "anydata" Data Node . . . . . . . . . . . . . . . . . 7 5.6. The "anyxml" Data Node . . . . . . . . . . . . . . . . . 7 5.7. Metadata Objects . . . . . . . . . . . . . . . . . . . . 7 6. Representing YANG Data Types in JSON Values . . . . . . . . . 7 6.1. Numeric Types . . . . . . . . . . . . . . . . . . . . . . 7 6.2. The "string" Type . . . . . . . . . . . . . . . . . . . . 7 6.3. The "boolean" Type . . . . . . . . . . . . . . . . . . . 7 6.4. The "enumeration" Type . . . . . . . . . . . . . . . . . 7 6.5. The "bits" Type . . . . . . . . . . . . . . . . . . . . . 7 6.6. The "binary" Type . . . . . . . . . . . . . . . . . . . . 7 6.7. The "leafref" Type . . . . . . . . . . . . . . . . . . . 7 Watsen Expires 18 November 2024 [Page 2] Internet-Draft XML Encoding of YANG Data May 2024 6.8. The "identityref" Type . . . . . . . . . . . . . . . . . 8 6.9. The "empty" Type . . . . . . . . . . . . . . . . . . . . 8 6.10. The "union" Type . . . . . . . . . . . . . . . . . . . . 8 6.11. The "instance-identifier" Type . . . . . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 9.1. Normative References . . . . . . . . . . . . . . . . . . 8 9.2. Informative References . . . . . . . . . . . . . . . . . 9 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction This document defines encoding rules for representing YANG [RFC7950] modeled configuration data, state data, parameters of Remote Procedure Call (RPC) operations or actions, and notifications defined using the Extensible Markup Language (XML) [XML]. 2. Terminology and Notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. The following terms are defined in [RFC7950]: * action * anydata * anyxml * augment * container * data node * data tree * identity * instance identifier * leaf * leaf-list * list * module * RPC operation * submodule The following terms are defined in [RFC6241]: * configuration data Watsen Expires 18 November 2024 [Page 3] Internet-Draft XML Encoding of YANG Data May 2024 * notification * state data 3. Properties of the XML Encoding This document defines XML encoding for YANG data trees and their subtrees. It is always assumed that there may be one or more top- level elements in XML-encoded configuration data and state data. RPC operations and notifications contain a single top-level element. Instances of YANG data nodes (leafs, containers, leaf-lists, lists, anydata nodes, and anyxml nodes) are encoded as XML elements having the name of the YANG data node. Section 4) defines how the name is qualified with a namespace, and the following sections deal with the value part. The encoding rules are identical for all types of data trees, i.e., configuration data, state data, parameters of RPC operations, actions, and notifications. With the exception of "anydata" encoding (Section 5.5), all rules in this document are also applicable to YANG 1.0 [RFC6020]. With the exception of anyxml and schema-less anydata nodes, it is possible to map an XML-encoded data tree to other encodings, such as the JSON encoding as defined in [RFC7951], and vice versa. However, such conversions require the YANG data model to be available. 4. Names and Namespaces An XML element name is always identical to the identifier of the corresponding YANG data node. All XML elements encoding YANG data are namespace qualified. The XML default namespace is never used in YANG encoded data. The namespace of an XML element is either inherited from its ancestor or set using the "xmlns" attribute in the element. The "xmlns" attribute may either set the XML default namespace or define and use a prefix for the namespace. For instance, the following two XML documents are the same. Document 1: Document 2: Watsen Expires 18 November 2024 [Page 4] Internet-Draft XML Encoding of YANG Data May 2024 The "namespace" statement of a module determines the namespace of all data node names defined in that module. If a data node is defined in a submodule, then the namespace of the main module is used. A namespace MUST be set for all top-level XML elements and then also whenever the namespaces of the data node and its parent node are different. For example, consider the following YANG module: module example-foomod { namespace "https://example.com/foomod"; prefix "foomod"; container top { leaf foo { type uint8; } } } If the data model consists only of this module, then the following is valid XML-encoded configuration data: 54 Note that the top-level element sets the default namespace which "foo" leaf inherits its parent container "top". Now, assume that the container "top" is augmented from another module, "example-barmod": Watsen Expires 18 November 2024 [Page 5] Internet-Draft XML Encoding of YANG Data May 2024 module example-barmod { namespace "https://example.com/barmod"; prefix "barmod"; import example-foomod { prefix "foomod"; } augment "/foomod:top" { leaf bar { type boolean; } } } Valid XML-encoded configuration data containing both leafs may then look like this: 54 true The "bar" leaf's element sets a new default namespace because its parent is defined in a different module. Prefixed namespace identifiers are sometimes needed when encoding values of the "identityref" and "instance-identifier" types. See Section 6.8 and Section 6.11 for details. 5. Encoding of YANG Data Node Instances 5.1. The "leaf" Data Node TBD 5.2. The "container" Data Node TBD 5.3. The "leaf-list" Data Node TBD Watsen Expires 18 November 2024 [Page 6] Internet-Draft XML Encoding of YANG Data May 2024 5.4. The "list" Data Node TBD 5.5. The "anydata" Data Node TBD 5.6. The "anyxml" Data Node TBD 5.7. Metadata Objects TBD 6. Representing YANG Data Types in JSON Values 6.1. Numeric Types TBD 6.2. The "string" Type TBD 6.3. The "boolean" Type TBD 6.4. The "enumeration" Type TBD 6.5. The "bits" Type TBD 6.6. The "binary" Type TBD 6.7. The "leafref" Type TBD Watsen Expires 18 November 2024 [Page 7] Internet-Draft XML Encoding of YANG Data May 2024 6.8. The "identityref" Type TBD 6.9. The "empty" Type TBD 6.10. The "union" Type TBD 6.11. The "instance-identifier" Type TBD 7. IANA Considerations This document registers one capability identifier URN from the "Network Configuration Protocol (NETCONF) Capability URNs" registry: 8. Security Considerations This document defines a language with which to write and read descriptions of management information. The language itself has no security impact on the Internet. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [I-D.yn-netmod-rfc7950bis] IETF, "The YANG 1.1 Data Modeling Language", 2024. Watsen Expires 18 November 2024 [Page 8] Internet-Draft XML Encoding of YANG Data May 2024 [XML] Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth Edition)", W3C Recommendation REC-xml-20081126, 26 November 2008, . 9.2. Informative References [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, August 2016, . Acknowledgements Substantial text in this document was copied from [RFC7951]. The authors wish to thank Ladislav Lhotka for authoring RFC 7951. Author's Address Kent Watsen Watsen Networks Watsen Expires 18 November 2024 [Page 9]