Network Working Group A. Bierman
Internet-Draft YumaWorks
Intended status: Standards Track M. Bjorklund
Expires: August 3, 2015 Tail-f Systems
K. Watsen
Juniper Networks
January 30, 2015

YANG Module Library


This document describes a YANG library, which provides information about all the YANG modules used by a device to represent management and protocol information. A YANG library can be shared by multiple protocols within the same device. Simple caching mechanisms are needed to allow clients to minimize retrieval of this information.

Status of This Memo

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This Internet-Draft will expire on August 3, 2015.

Copyright Notice

Copyright (c) 2015 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 ( 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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

Table of Contents

1. Introduction

There is a need for standard mechanisms to identify the YANG modules and submodules that are in use by each server that utilizes YANG-based data abstraction. If a large number of YANG modules are utilized by the server, then the YANG library information needed can be relatively large. This information changes very infrequently, so it is important that clients be able to cache the YANG library and easily identify if their cache is out-of-date.

YANG library information can be different on every server, and can change at run-time or across a server reboot. Typically firmware upgrades are required to change the set of YANG modules used by a server.

The following information is needed by a client application (for each YANG module in the library) to fully utilize the YANG data modeling language.

1.1. Terminology

The keywords "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].

1.1.1. NETCONF

The following terms are defined in [RFC6241]:

1.1.2. YANG

The following terms are defined in [RFC6020]:

1.1.3. Terms

The following terms are used within this document:

1.1.4. Tree Diagrams

A simplified graphical representation of the data model is used in this document. The meaning of the symbols in these diagrams is as follows:

2. YANG Module Library

The "ietf‑yang‑library" module provides information about the YANG library used by a server.

YANG Tree Diagram for "ietf‑yang‑library" module:

  +--ro modules
      +--ro module-set-id?   string
      +--ro module* [name revision]
         +--ro name           yang:yang-identifier
         +--ro revision       union
         +--ro schema?        inet:uri
         +--ro namespace      inet:uri
         +--ro feature*       yang:yang-identifier
         +--ro deviation*     yang:yang-identifier
         +--ro conformance    boolean
         +--ro submodules
            +--ro submodule* [name revision]
               +--ro name        yang:yang-identifier
               +--ro revision    union
               +--ro schema?     inet:uri

2.1. modules

This mandatory container holds the identifiers for the YANG data model modules supported by the server.

2.1.1. modules/module

This mandatory list contains one entry for each YANG data model module supported by the server. There MUST be an instance of this list for every YANG module that is used by the server.

2.2. YANG Library Module

The "ietf‑yang‑library" module defines monitoring information for the YANG modules used by a RESTCONF server.

The "ietf‑yang‑types" and "ietf‑inet‑types" modules from [RFC6991] are used by this module for some type definitions.

RFC Ed.: update the date below with the date of RFC publication and remove this note.

<CODE BEGINS> file "ietf-yang-library@2015-01-30.yang"

module ietf-yang-library {
  namespace "urn:ietf:params:xml:ns:yang:ietf-yang-library";
  prefix "yanglib";

  import ietf-yang-types { prefix yang; }
  import ietf-inet-types { prefix inet; }

    "IETF NETCONF (Network Configuration) Working Group";

    "WG Web:   <>
     WG List:  <>

     WG Chair: Mehmet Ersue

     WG Chair: Mahesh Jethanandani

     Editor:   Andy Bierman

     Editor:   Martin Bjorklund

     Editor:   Kent Watsen

    "This module contains monitoring information about the YANG
     modules and submodules that are used within a YANG-based

     Copyright (c) 2015 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents

     This version of this YANG module is part of RFC XXXX; see
     the RFC itself for full legal notices.";

  // RFC Ed.: replace XXXX with actual RFC number and remove this
  // note.

  // RFC Ed.: remove this note
  // Note: extracted from draft-ietf-netconf-yang-library-00.txt

  // RFC Ed.: update the date below with the date of RFC publication
  // and remove this note.
  revision 2015-01-30 {
      "Initial revision.";
      "RFC XXXX: YANG Module Library.";

  typedef revision-identifier {
    type string {
      pattern '\d{4}-\d{2}-\d{2}';
      "Represents a specific date in YYYY-MM-DD format.
       TBD: make pattern more precise to exclude leading zeros.";

  grouping module {
      "The module data structure is represented as a grouping
       so it can be reused in configuration or another monitoring
       data structure.";

    grouping common-leafs {
        "Common parameters for YANG modules and submodules.";

      leaf name {
        type yang:yang-identifier;
        description "The YANG module or submodule name.";
      leaf revision {
        type union {
          type revision-identifier;
          type string { length 0; }
          "The YANG module or submodule revision date.
           An empty string is used if no revision statement
           is present in the YANG module or submodule.";
      leaf schema {
        type inet:uri;
          "Contains a URL that represents the YANG schema
           resource for this module or submodule.

           This leaf will only be present if there is a URL
           available for retrieval of the schema for this entry.";

    list module {
      key "name revision";
        "Each entry represents one module currently
         supported by the server.";

      uses common-leafs;

      leaf namespace {
        type inet:uri;
        mandatory true;
          "The XML namespace identifier for this module.";
      leaf-list feature {
        type yang:yang-identifier;
          "List of YANG feature names from this module that are
           supported by the server.";
      leaf-list deviation {
        type yang:yang-identifier;
          "List of YANG deviation module names used by this
           server to modify the conformance of the module
           associated with this entry.";
      leaf conformance {
        type boolean;
        mandatory true;
          "If 'true', then the server is claiming conformance to
           the YANG module identified in this entry.

           If 'false', then the server is not claiming any
           conformance for the YANG module identified by this
           entry. The module may be needed for reusable definitions
           such as extensions, features, identifies, typedefs,
           or groupings.";
      container submodules {
          "Contains information about all the submodules used
           by the parent module entry";

        list submodule {
          key "name revision";
            "Each entry represents one submodule within the
             parent module.";
          uses common-leafs;
    } // list module
  }  // grouping module

  container modules {
    config false;
      "Contains YANG module monitoring information.";

    leaf module-set-id {
      type string;
        "Contains a server-specific identifier representing
         the current set of modules and submodules.  The
         server MUST change the value of this leaf if the
         information represented by the 'module' list instances
         has changed.";

    uses module;



3. IANA Considerations

3.1. YANG Module Registry

This document registers one URI in the IETF XML registry [RFC3688]. Following the format in RFC 3688, the following registration is requested to be made.

     URI: urn:ietf:params:xml:ns:yang:ietf-yang-library
     Registrant Contact: The NETMOD WG of the IETF.
     XML: N/A, the requested URI is an XML namespace.

This document registers one YANG module in the YANG Module Names registry [RFC6020].

  name:         ietf-yang-library
  namespace:    urn:ietf:params:xml:ns:yang:ietf-yang-library
  prefix:       yanglib
  // RFC Ed.: replace XXXX with RFC number and remove this note
  reference:    RFC XXXX

4. Security Considerations

This section provides security considerations for the information that is defined by the "ietf‑yang‑library" module.

   [FIXME: follow template for sec. considerations]

5. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, June 2011.
[RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, July 2013.

Appendix A. Change Log

    -- RFC Ed.: remove this section before publication.

A.1. draft-ietf-netconf-restconf-03 to 00

Appendix B. Open Issues

    -- RFC Ed.: remove this section before publication.

The YANG Library issue tracker can be found here:

Authors' Addresses

Andy Bierman YumaWorks EMail:
Martin Bjorklund Tail-f Systems EMail:
Kent Watsen Juniper Networks EMail: