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;
  }

  organization
    "IETF NETCONF (Network Configuration) Working Group";

  contact
    "WG Web:   <https://datatracker.ietf.org/wg/netconf/>
     WG List:  <mailto:netconf@ietf.org>

     WG Chair: Mehmet Ersue
               <mailto:mehmet.ersue@nsn.com>

     WG Chair: Mahesh Jethanandani
               <mailto:mjethanandani@gmail.com>

     Editor:   Andy Bierman
               <mailto:andy@yumaworks.com>

     Editor:   Martin Bjorklund
               <mailto:mbj@tail-f.com>

     Editor:   Kent Watsen
               <mailto:kwatsen@juniper.net>";

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

     Copyright (c) 2016 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
     (http://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC 7895; see
     the RFC itself for full legal notices.";

  revision 2016-06-21 {
    description
      "Initial revision.";
    reference
      "RFC 7895: YANG Module Library.";
  }

  /*
   * Typedefs
   */

  typedef revision-identifier {
    type string {
      pattern '\d{4}-\d{2}-\d{2}';
    }
    description
      "Represents a specific date in YYYY-MM-DD format.";
  }

  /*
   * Groupings
   */

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

    grouping common-leafs {
      description
        "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; }
        }
        description
          "The YANG module or submodule revision date.
           A zero-length string is used if no revision statement
           is present in the YANG module or submodule.";
      }
    }

    grouping schema-leaf {
      description
        "Common schema leaf parameter for modules and submodules.";

      leaf schema {
        type inet:uri;
        description
          "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";
      description
        "Each entry represents one revision of one module
         currently supported by the server.";

      uses common-leafs;
      uses schema-leaf;

      leaf namespace {
        type inet:uri;
        mandatory true;
        description
          "The XML namespace identifier for this module.";
      }
      leaf-list feature {
        type yang:yang-identifier;
        description
          "List of YANG feature names from this module that are
           supported by the server, regardless of whether they are
           defined in the module or any included submodule.";
      }
      list deviation {
        key "name revision";
        description
          "List of YANG deviation module names and revisions
           used by this server to modify the conformance of
           the module associated with this entry.  Note that
           the same module can be used for deviations for
           multiple modules, so the same entry MAY appear
           within multiple 'module' entries.

           The deviation module MUST be present in the 'module'
           list, with the same name and revision values.
           The 'conformance-type' value will be 'implement' for
           the deviation module.";
        uses common-leafs;
      }
      leaf conformance-type {
        type enumeration {
          enum implement {
            description
              "Indicates that the server implements one or more
               protocol-accessible objects defined in the YANG module
               identified in this entry.  This includes deviation
               statements defined in the module.

               For YANG version 1.1 modules, there is at most one
               module entry with conformance type 'implement' for a
               particular module name, since YANG 1.1 requires that,
               at most, one revision of a module is implemented.

               For YANG version 1 modules, there SHOULD NOT be more
               than one module entry for a particular module name.";
          }
          enum import {
            description
              "Indicates that the server imports reusable definitions
               from the specified revision of the module but does
               not implement any protocol-accessible objects from
               this revision.

               Multiple module entries for the same module name MAY
               exist.  This can occur if multiple modules import the
               same module but specify different revision dates in
               the import statements.";
          }
        }
        mandatory true;
        description
          "Indicates the type of conformance the server is claiming
           for the YANG module identified by this entry.";
      }
      list submodule {
        key "name revision";
        description
          "Each entry represents one submodule within the
           parent module.";
        uses common-leafs;
        uses schema-leaf;
      }
    }
  }

  /*
   * Operational state data nodes
   */

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

    leaf module-set-id {
      type string;
      mandatory true;
      description
        "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-list;
  }

  /*
   * Notifications
   */

  notification yang-library-change {
    description
      "Generated when the set of modules and submodules supported
       by the server has changed.";
    leaf module-set-id {
      type leafref {
        path "/yanglib:modules-state/yanglib:module-set-id";
      }
      mandatory true;
      description
        "Contains the module-set-id value representing the
         set of modules and submodules supported at the server at
         the time the notification is generated.";
    }
  }

}