Network Working Group A. Bierman
Internet-Draft YumaWorks
Intended status: Standards Track M. Bjorklund
Expires: January 9, 2017 Tail-f Systems
K. Watsen
Juniper Networks
July 8, 2016

YANG Patch Media Type
draft-ietf-netconf-yang-patch-10

Abstract

This document describes a method for applying patches to configuration datastores using data defined with the YANG data modeling language.

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 http://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 January 9, 2017.

Copyright Notice

Copyright (c) 2016 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 (http://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 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 patch datastores defined in [RFC6241], which contain conceptual data that conforms to schema specified with YANG [I-D.ietf-netmod-rfc6020bis]. An "ordered edit list" approach is needed to provide client developers with more precise client control of the edit procedure than existing mechanisms.

This document defines a media type for a YANG-based editing mechanism that can be used with the HTTP PATCH method [RFC5789]. YANG Patch is designed to support the RESTCONF protocol, defined in [I-D.ietf-netconf-restconf].

It may be possible to use YANG Patch with other protocols besides RESTCONF. This is outside the scope of this document. It may be possible to use YANG Patch with datastore types other than a configuration datastore. This is outside the scope of this document.

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. HTTP

The following terms are defined in [RFC7230]:

1.1.3. YANG

The following terms are defined in [I-D.ietf-netmod-rfc6020bis]:

1.1.4. RESTCONF

The following terms are defined in [I-D.ietf-netconf-restconf]:

1.1.5. YANG Patch

The following terms are used within this document:

1.1.6. 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 Patch

A "YANG Patch" is an ordered list of edits that are applied to the target datastore by the server. The specific fields are defined in the YANG module in Section 3.

For RESTCONF, the YANG Patch operation is invoked by the client by sending a PATCH method request with a representation using either the "application/yang‑patch" or "application/yang‑patch+json" media type. A message body representing the YANG Patch input parameters MUST be provided.

The RESTCONF server MUST return the Accept-Patch header field in an OPTIONS response, as specified in [RFC5789], which includes the media type for YANG Patch.

Example:

  Accept-Patch: application/yang-patch,application/yang-patch+json
	    

A YANG Patch can be encoded in XML format according to [W3C.REC-xml-20081126]. It can also be encoded in JSON, according to "JSON Encoding of Data Modeled with YANG" [I-D.ietf-netmod-yang-json]. If any meta-data needs to be sent in a JSON message, it is encoded according to "Defining and Using Metadata with YANG" [I-D.ietf-netmod-yang-metadata].

2.1. Target Resource

The YANG Patch operation uses the RESTCONF target resource URI to identify the resource that will be patched. This can be the datastore resource itself, i.e., "{+restconf}/data", or it can be a configuration data resource within the datastore resource, e.g., {+restconf/data/ietf-interfaces:interfaces".

Each edit with a YANG Patch identifies a target data node for the associated edit. This is described in Section 2.4.

2.2. yang-patch Input

A YANG patch is optionally identified by a unique "patch‑id" and it may have an optional comment. A patch is an ordered collection of edits. Each edit is identified by an "edit‑id" and it has an edit operation (create, delete, insert, merge, move, replace, remove) that is applied to the target resource. Each edit can be applied to a sub-resource "target" within the target resource. If the operation is "insert" or "move", then the "where" parameter indicates how the node is inserted or moved. For values "before" and "after", the "point" parameter specifies the data node insertion point.

A data element representing the YANG Patch is sent by the client to specify the edit operation request. When used with the HTTP PATCH method, this data is identified by the YANG Patch media type.

YANG Tree Diagram For "yang‑patch" Container

   +--rw yang-patch
      +--rw patch-id?   string
      +--rw comment?    string
      +--rw edit [edit-id]
         +--rw edit-id      string
         +--rw operation    enumeration
         +--rw target       target-resource-offset
         +--rw point?       target-resource-offset
         +--rw where?       enumeration
         +--rw value
	    

2.3. yang-patch-status Output

A data element representing the YANG Patch Status is returned to the client to report the detailed status of the edit operation. When used with the HTTP PATCH method, this data is identified by the YANG Patch Status media type, and the syntax specification is defined in Section 3.

YANG Tree Diagram For "yang‑patch‑status" Container:

   +--rw yang-patch-status
      +--rw patch-id?        string
      +--rw (global-status)?
      |  +--:(global-errors)
      |  |  +--ro errors
      |  |
      |  +--:(ok)
      |     +--rw ok?              empty
      +--rw edit-status
         +--rw edit [edit-id]
            +--rw edit-id     string
            +--rw (edit-status-choice)?
               +--:(ok)
               |  +--rw ok?         empty
               +--:(errors)
                  +--ro errors
	    

2.4. Target Data Node

The target data node for each edit operation is determined by the value of the target resource in the request and the "target" leaf within each "edit" entry.

If the target resource specified in the request URI identifies a datastore resource, then the path string in the "target" leaf is treated as an absolute path expression identifying the target data node for the corresponding edit. The first node specified in the "target" leaf is a top-level data node defined within a YANG module. The "target" leaf MUST NOT contain a single forward slash "/", since this would identify the datastore resource, not a data resource.

If the target resource specified in the request URI identifies a configuration data resource, then the path string in the "target" leaf is treated as a relative path expression. The first node specified in the "target" leaf is a child configuration data node of the data node associated with the target resource. If the "target" leaf contains a single forward slash "/", then the target data node is the target resource data node.

2.5. Edit Operations

Each YANG patch edit specifies one edit operation on the target data node. The set of operations is aligned with the NETCONF edit operations, but also includes some new operations.

YANG Patch Edit Operations
Operation Description
create create a new data resource if it does not already exist or error
delete delete a data resource if it already exists or error
insert insert a new user-ordered data resource
merge merge the edit value with the target data resource; create if it does not already exist
move re-order the target data resource
replace replace the target data resource with the edit value
remove remove a data resource if it already exists or no error

2.6. Successful Edit Response Handling

If a YANG Patch is completed without errors, the server SHOULD return a "yang‑patch‑status" message.

The server will save the running datastore to non-volatile storage if it supports non-volatile storage, and if the running datastore contents have changed. This will be done in an implementation-specific manner.

Refer to Appendix D.1.2 for a example of a successful YANG Patch response.

2.7. Error Handling

If a well-formed, schema-valid YANG Patch message is received, then the server will process the supplied edits in ascending order. The following error modes apply to the processing of this edit list:

If a YANG Patch is completed with errors, the server SHOULD return a "yang‑patch‑status" message.

Refer to Appendix D.1.1 for a example of an error YANG Patch response.

2.8. yang-patch RESTCONF Capability

A URI is defined to identify the YANG Patch extension to the base RESTCONF protocol. If the server supports the YANG Patch media type, then the "yang‑patch" RESTCONF capability defined in Section 4.3 MUST be present in the "capability" leaf-list in the "ietf‑restconf‑monitoring" module defined in [I-D.ietf-netconf-restconf].

3. YANG Module

The "ietf‑yang‑patch" module defines conceptual definitions with the 'yang‑data' extension statements, which are not meant to be implemented as datastore contents by a server.

The "ietf‑restconf" module from [I-D.ietf-netconf-restconf] is used by this module for the 'yang‑data' extension definition.

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

<CODE BEGINS> file "ietf-yang-patch@2016-07-07.yang"

module ietf-yang-patch {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-yang-patch";
  prefix "ypatch";

  import ietf-restconf { prefix rc; }

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

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

     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 conceptual YANG specifications
     for the YANG Patch and YANG Patch Status data structures.

     Note that the YANG definitions within this module do not
     represent configuration data of any kind.
     The YANG grouping statements provide a normative syntax
     for XML and JSON message encoding purposes.

     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 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-patch-10.txt

  // RFC Ed.: update the date below with the date of RFC publication
  // and remove this note.
  revision 2016-07-07 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: YANG Patch Media Type.";
  }

  typedef target-resource-offset {
    type string;
    description
      "Contains a data resource identifier string representing
       a sub-resource within the target resource.
       The document root for this expression is the
       target resource that is specified in the
       protocol operation (e.g., the URI for the PATCH request).

       This string is encoded according the same rules as
       a data resource identifier in a RESTCONF Request URI.";

  // RFC Ed.: replace "draft-ietf-netconf-restconf" below
  // with RFC XXXX, where XXXX is the number of the RESTCONF RFC,
  // and remove this note.

    reference
       "draft-ietf-netconf-restconf, section 3.5.3";
  }

  rc:yang-data "yang-patch" {
    uses yang-patch;
  }

  rc:yang-data "yang-patch-status" {
    uses yang-patch-status;
  }

  grouping yang-patch {

    description
      "A grouping that contains a YANG container
       representing the syntax and semantics of a
       YANG Patch edit request message.";

    container yang-patch {
      description
        "Represents a conceptual sequence of datastore edits,
         called a patch. Each patch is given a client-assigned
         patch identifier. Each edit MUST be applied
         in ascending order, and all edits MUST be applied.
         If any errors occur, then the target datastore MUST NOT
         be changed by the patch operation.

         YANG datastore validation is performed before any edits
         have been applied to the running datastore.

         It is possible for a datastore constraint violation to occur
         due to any node in the datastore, including nodes not
         included in the edit list. Any validation errors MUST
         be reported in the reply message.";

      reference
        "draft-ietf-netmod-rfc6020bis, section 8.3.";

      leaf patch-id {
        type string;
        description
          "An arbitrary string provided by the client to identify
           the entire patch.  This value SHOULD be present in any
           audit logging records generated by the server for the
           patch. Error messages returned by the server pertaining
           to this patch will be identified by this patch-id value.";
      }

      leaf comment {
        type string;
        description
          "An arbitrary string provided by the client to describe
           the entire patch.  This value SHOULD be present in any
           audit logging records generated by the server for the
           patch.";
      }

      list edit {
        key edit-id;
        ordered-by user;

        description
          "Represents one edit within the YANG Patch
           request message.  The edit list is applied
           in the following manner:

             - The first edit is conceptually applied to a copy
               of the existing target datastore, e.g., the
               running configuration datastore.
             - Each ascending edit is conceptually applied to
               the result of the previous edit(s).
             - After all edits have been successfully processed,
               the result is validated according to YANG constraints.
             - If successful, the server will attempt to apply
               the result to the target datastore. ";

        leaf edit-id {
          type string;
          description
            "Arbitrary string index for the edit.
             Error messages returned by the server pertaining
             to a specific edit will be identified by this
             value.";
        }

        leaf operation {
          type enumeration {
            enum create {
              description
                "The target data node is created using the
                 supplied value, only if it does not already
                 exist.get' leaf identifies the data node to be
                 created, not the parent data node.";
            }
            enum delete {
              description
                "Delete the target node, only if the data resource
                 currently exists, otherwise return an error.";
            }
            enum insert {
              description
                "Insert the supplied value into a user-ordered
                 list or leaf-list entry. The target node must
                 represent a new data resource. If the 'where'
                 parameter is set to 'before' or 'after', then
                 the 'point' parameter identifies the insertion
                 point for the target node.";
            }
            enum merge {
              description
                "The supplied value is merged with the target data
                 node.";
            }
            enum move {
              description
                "Move the target node. Reorder a user-ordered
                 list or leaf-list. The target node must represent
                 an existing data resource. If the 'where' parameter
                 is set to 'before' or 'after', then the 'point'
                 parameter identifies the insertion point to move
                 the target node.";
            }
            enum replace {
              description
                "The supplied value is used to replace the target
                 data node.";
            }
            enum remove {
              description
                "Delete the target node if it currently exists.";
            }
          }
          mandatory true;
          description
            "The datastore operation requested for the associated
             edit entry";
        }

        leaf target {
          type target-resource-offset;
          mandatory true;
          description
            "Identifies the target data node for the edit
             operation. If the target has the value '/', then
             the target data node is the target resource.
             The target node MUST identify a data resource,
             not the datastore resource.";
        }

        leaf point {
          when "(../operation = 'insert' or ../operation = 'move') "
             + "and (../where = 'before' or ../where = 'after')" {
            description
              "Point leaf only applies for insert or move
               operations, before or after an existing entry.";
          }
          type target-resource-offset;
          description
            "The absolute URL path for the data node that is being
             used as the insertion point or move point for the
             target of this edit entry.";
        }

        leaf where {
          when "../operation = 'insert' or ../operation = 'move'" {
            description
              "Where leaf only applies for insert or move
               operations.";
          }
          type enumeration {
            enum before {
              description
                "Insert or move a data node before the data resource
                 identified by the 'point' parameter.";
            }
            enum after {
              description
                "Insert or move a data node after the data resource
                 identified by the 'point' parameter.";
            }
            enum first {
              description
                "Insert or move a data node so it becomes ordered
                 as the first entry.";
            }
            enum last {
              description
                "Insert or move a data node so it becomes ordered
                 as the last entry.";
            }
          }
          default last;
          description
            "Identifies where a data resource will be inserted or
             moved. YANG only allows these operations for
             list and leaf-list data nodes that are ordered-by
             user.";
        }

        anydata value {
          when "../operation = 'create' "
             + "or ../operation = 'merge' "
             + "or ../operation = 'replace' "
             + "or ../operation = 'insert'" {
            description
              "Value node only used for create, merge,
               replace, and insert operations";
          }
          description
            "Value used for this edit operation.  The anydata 'value'
             contains the target resource associated with the
             'target' leaf.

             For example, suppose the target node is a YANG container
             named foo:

                 container foo {
                   leaf a { type string; }
                   leaf b { type int32; }
                 }

             The 'value' node contains one instance of foo:

                 <value>
                    <foo xmlns='example-foo-namespace'>
                       <a>some value</a>
                       <b>42</b>
                    </foo>
                 </value>
              ";
        }
      }
    }

  } // grouping yang-patch


  grouping yang-patch-status {

    description
      "A grouping that contains a YANG container
       representing the syntax and semantics of
       YANG Patch status response message.";

    container yang-patch-status {
      description
        "A container representing the response message
         sent by the server after a YANG Patch edit
         request message has been processed.";

      leaf patch-id {
        type string;
        description
          "The patch-id value used in the request.
           If there was no patch-id present in the request
           then this field will not be present.";
      }

      choice global-status {
        description
          "Report global errors or complete success.
           If there is no case selected then errors
           are reported in the edit-status container.";

        case global-errors {
          uses rc:errors;
          description
            "This container will be present if global
             errors unrelated to a specific edit occurred.";
        }
        leaf ok {
          type empty;
          description
            "This leaf will be present if the request succeeded
             and there are no errors reported in the edit-status
             container.";
        }
      }

      container edit-status {
        description
          "This container will be present if there are
           edit-specific status responses to report.
           If all edits succeeded and the 'global-status'
           returned  is 'ok', then a server MAY omit this
           container";

        list edit {
          key edit-id;

          description
            "Represents a list of status responses,
             corresponding to edits in the YANG Patch
             request message.  If an edit entry was
             skipped or not reached by the server,
             then this list will not contain a corresponding
             entry for that edit.";

          leaf edit-id {
            type string;
             description
               "Response status is for the edit list entry
                with this edit-id value.";
          }
          choice edit-status-choice {
            description
              "A choice between different types of status
               responses for each edit entry.";
            leaf ok {
              type empty;
              description
                "This edit entry was invoked without any
                 errors detected by the server associated
                 with this edit.";
            }
            case errors {
              uses rc:errors;
              description
                "The server detected errors associated with the
                  edit identified by the same edit-id value.";
            }
          }
        }
      }
    }
  }  // grouping yang-patch-status

}
	    

<CODE ENDS>

4. IANA Considerations

4.1. YANG Module Registry

This document registers one URI as a namespace 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-patch
     Registrant Contact: The NETCONF 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-patch
  namespace:    urn:ietf:params:xml:ns:yang:ietf-yang-patch
  prefix:       ypatch
  // RFC Ed.: replace XXXX with RFC number and remove this note
  reference:    RFC XXXX
	    

4.2. Media Types

4.2.1. Media Type application/yang-patch

   Type name: application

   Subtype name: yang-patch

   Required parameters: None

   Optional parameters: None

  // RFC Ed.: replace draft-ietf-netmod-rfc6020bis with
  // the actual RFC reference for YANG 1.1, and remove this note.

  // RFC Ed.: replace 'XXXX' with the real RFC number,
  // and remove this note

   Encoding considerations: 8-bit
      Each conceptual YANG data node is encoded according to the
      XML Encoding Rules and Canonical Format for the specific
      YANG data node type defined in [draft-ietf-netmod-rfc6020bis].
      In addition, the "yang-patch" YANG data template found
      in [RFCXXXX] defines the structure of a YANG Patch request.

  // RFC Ed.: replace 'NN' in Section NN of [RFCXXXX] with the
  // section number for Security Considerations
  // Replace 'XXXX' in Section NN of [RFCXXXX] with the actual
  // RFC number, and remove this note.

   Security considerations: Security considerations related
      to the generation and consumption of RESTCONF messages
      are discussed in Section NN of [RFCXXXX].
      Additional security considerations are specific to the
      semantics of particular YANG data models. Each YANG module
      is expected to specify security considerations for the
      YANG data defined in that module.

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

   Interoperability considerations: [RFCXXXX] specifies the format
      of conforming messages and the interpretation thereof.

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

   Published specification: RFC XXXX

   Applications that use this media type: Instance document
     data parsers used within a protocol or automation tool
     that utilize the YANG Patch data structure.

   Fragment identifier considerations: The fragment field in the
      request URI has no defined purpose.

   Additional information:

     Deprecated alias names for this type: N/A
     Magic number(s): N/A
     File extension(s): .xml
     Macintosh file type code(s): "TEXT"

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

   Person & email address to contact for further information: See
      Authors' Addresses section of [RFCXXXX].

   Intended usage: COMMON

   Restrictions on usage: N/A

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

   Author: See Authors' Addresses section of [RFCXXXX].

   Change controller: Internet Engineering Task Force
      (mailto:iesg&ietf.org).

   Provisional registration? (standards tree only): no
	    

4.2.2. Media Type application/yang-patch+json

   Type name: application

   Subtype name: yang-patch+json

   Required parameters: None

   Optional parameters: None

  // RFC Ed.: replace draft-ietf-netmod-yang-json with
  // the actual RFC reference for JSON Encoding of YANG Data,
  //  and remove this note.

  // RFC Ed.: replace draft-ietf-netmod-yang-metadata with
  // the actual RFC reference for JSON Encoding of YANG Data,
  //  and remove this note.

  // RFC Ed.: replace 'XXXX' with the real RFC number,
  // and remove this note

   Encoding considerations: 8-bit
      Each conceptual YANG data node is encoded according to
      [draft-ietf-netmod-yang-json]. A data annotation is
      encoded according to [draft-ietf-netmod-yang-metadata]
      In addition, the "yang-patch" YANG data template found
      in [RFCXXXX] defines the structure of a YANG Patch request.

  // RFC Ed.: replace 'NN' in Section NN of [RFCXXXX] with the
  // section number for Security Considerations
  // Replace 'XXXX' in Section NN of [RFCXXXX] with the actual
  // RFC number, and remove this note.

   Security considerations: Security considerations related
      to the generation and consumption of RESTCONF messages
      are discussed in Section NN of [RFCXXXX].
      Additional security considerations are specific to the
      semantics of particular YANG data models. Each YANG module
      is expected to specify security considerations for the
      YANG data defined in that module.

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

   Interoperability considerations: [RFCXXXX] specifies the format
      of conforming messages and the interpretation thereof.

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

   Published specification: RFC XXXX

   Applications that use this media type: Instance document
     data parsers used within a protocol or automation tool
     that utilize the YANG Patch data structure.

   Fragment identifier considerations: The syntax and semantics
      of fragment identifiers are the same as specified for the
     "application/json" media type.

   Additional information:

     Deprecated alias names for this type: N/A
     Magic number(s): N/A
     File extension(s): .json
     Macintosh file type code(s): "TEXT"

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

   Person & email address to contact for further information: See
      Authors' Addresses section of [RFCXXXX].

   Intended usage: COMMON

   Restrictions on usage: N/A

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

   Author: See Authors' Addresses section of [RFCXXXX].

   Change controller: Internet Engineering Task Force
      (mailto:iesg&ietf.org).

   Provisional registration? (standards tree only): no
	    

4.3. RESTCONF Capability URNs

This document registers one capability identifier in "RESTCONF Protocol Capability URNs" registry

  Index
     Capability Identifier
  ------------------------

  :yang-patch
      urn:ietf:params:restconf:capability:yang-patch:1.0
	    

5. Security Considerations

The YANG Patch media type does not introduce any significant new security threats, beyond what is described in [I-D.ietf-netconf-restconf]. This document defines edit processing instructions for a variant of the PATCH method, as used within the RESTCONF protocol.

It may be possible to use YANG Patch with other protocols besides RESTCONF, which is outside the scope of this document.

It is important for server implementations to carefully validate all the edit request parameters in some manner. If the entire YANG Patch request cannot be completed, then no configuration changes to the system are done.

A server implementation SHOULD attempt to prevent system disruption due to partial processing of the YANG Patch edit list. It may be possible to construct an attack on such a server, which relies on the edit processing order mandated by YANG Patch.

6. Normative References

[I-D.ietf-netconf-restconf] Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", Internet-Draft draft-ietf-netconf-restconf-13, April 2016.
[I-D.ietf-netmod-rfc6020bis] Bjorklund, M., "The YANG 1.1 Data Modeling Language", Internet-Draft draft-ietf-netmod-rfc6020bis-11, February 2016.
[I-D.ietf-netmod-yang-json] Lhotka, L., "JSON Encoding of Data Modeled with YANG", Internet-Draft draft-ietf-netmod-yang-json-10, March 2016.
[I-D.ietf-netmod-yang-metadata] Lhotka, L., "Defining and Using Metadata with YANG", Internet-Draft draft-ietf-netmod-yang-metadata-07, March 2016.
[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, DOI 10.17487/RFC3688, January 2004.
[RFC5789] Dusseault, L. and J. Snell, "PATCH Method for HTTP", RFC 5789, March 2010.
[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.
[RFC7159] Bray, T., "The JavaScript Object Notation (JSON) Data Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March 2014.
[RFC7230] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014.
[W3C.REC-xml-20081126] Yergeau, F., Maler, E., Paoli, J., Sperberg-McQueen, C. and T. Bray, "Extensible Markup Language (XML) 1.0 (Fifth Edition)", World Wide Web Consortium Recommendation REC-xml-20081126, November 2008.

Appendix A. Acknowledgements

The authors would like to thank the following people for their contributions to this document: Rex Fernando.

Contributions to this material by Andy Bierman are based upon work supported by the The Space & Terrestrial Communications Directorate (S&TCD) under Contract No. W15P7T-13-C-A616. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of The Space & Terrestrial Communications Directorate (S&TCD).

Appendix B. Change Log

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

The YANG Patch issue tracker can be found here: https://github.com/netconf-wg/yang-patch/issues

B.1. v09 to v10

B.2. v08 to v09

B.3. v07 to v08

B.4. v06 to v07

B.5. v05 to v06

B.6. v04 to v05

B.7. v03 to v04

B.8. v02 to v03

B.9. v01 to v02

B.10. v00 to v01

B.11. bierman:yang-patch-00 to ietf:yang-patch-00

Appendix C. Open Issues

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

Refer to the github issue tracker for any open issues:

   https://github.com/netconf-wg/yang-patch/issues
	    

Appendix D. Example YANG Module

The example YANG module used in this document represents a simple media jukebox interface. The "example‑jukebox" YANG module is defined in [I-D.ietf-netconf-restconf].

YANG Tree Diagram for "example‑jukebox" Module:

   +--rw jukebox!
      +--rw library
      |  +--rw artist* [name]
      |  |  +--rw name     string
      |  |  +--rw album* [name]
      |  |     +--rw name     string
      |  |     +--rw genre?   identityref
      |  |     +--rw year?    uint16
      |  |     +--rw admin
      |  |     |  +--rw label?              string
      |  |     |  +--rw catalogue-number?   string
      |  |     +--rw song* [name]
      |  |        +--rw name        string
      |  |        +--rw location    string
      |  |        +--rw format?     string
      |  |        +--rw length?     uint32
      |  +--ro artist-count?   uint32
      |  +--ro album-count?    uint32
      |  +--ro song-count?     uint32
      +--rw playlist* [name]
      |  +--rw name           string
      |  +--rw description?   string
      |  +--rw song* [index]
      |     +--rw index    uint32
      |     +--rw id       leafref
      +--rw player
         +--rw gap?   decimal64
	    
  rpcs:
	    
   +---x play
      +--ro input
         +--ro playlist       string
         +--ro song-number    uint32
	    

D.1. YANG Patch Examples

This section includes RESTCONF examples. Most examples are shown in JSON encoding [RFC7159], and some are shown in XML encoding [W3C.REC-xml-20081126].

D.1.1. Add Resources: Error

The following example shows several songs being added to an existing album. Each edit contains one song. The first song already exists, so an error will be reported for that edit. The rest of the edits were not attempted, since the first edit failed. The XML encoding is used in this example.

 Request from client:

   PATCH /restconf/data/example-jukebox:jukebox/
      library/artist=Foo%20Fighters/album=Wasting%20Light HTTP/1.1
   Host: example.com
   Accept: application/yang-data
   Content-Type: application/yang-patch
	    
   <yang-patch xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-patch">
     <patch-id>add-songs-patch</patch-id>
     <edit>
       <edit-id>edit1</edit-id>
       <operation>create</operation>
       <target>/song</target>
       <value>
         <song xmlns="http://example.com/ns/example-jukebox">
           <name>Bridge Burning</name>
           <location>/media/bridge_burning.mp3</location>
           <format>MP3</format>
           <length>288</length>
         </song>
       </value>
     </edit>
     <edit>
       <edit-id>edit2</edit-id>
       <operation>create</operation>
       <target>/song</target>
       <value>
         <song xmlns="http://example.com/ns/example-jukebox">
           <name>Rope</name>
           <location>/media/rope.mp3</location>
           <format>MP3</format>
           <length>259</length>
         </song>
       </value>
     </edit>
     <edit>
       <edit-id>edit3</edit-id>
       <operation>create</operation>
       <target>/song</target>
       <value>
         <song xmlns="http://example.com/ns/example-jukebox">
           <name>Dear Rosemary</name>
           <location>/media/dear_rosemary.mp3</location>
           <format>MP3</format>
           <length>269</length>
         </song>
       </value>
     </edit>
   </yang-patch>
	    
 XML Response from server:

   HTTP/1.1 409 Conflict
   Date: Mon, 23 Apr 2012 13:01:20 GMT
   Server: example-server
   Last-Modified: Mon, 23 Apr 2012 13:01:20 GMT
   Content-Type: application/yang-data
	    
   <yang-patch-status
      xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-patch">
     <patch-id>add-songs-patch</patch-id>
     <edit-status>
       <edit>
          <edit-id>edit1</edit-id>
          <errors>
             <error>
                <error-type>application</error-type>
                <error-tag>data-exists</error-tag>
                <error-path
                  xmlns:jb="http://example.com/ns/example-jukebox">
                  /jb:jukebox/jb:library
                  /jb:artist[jb:name='Foo Fighters']
                  /jb:album[jb:name='Wasting Light']
                  /jb:song[jb:name='Burning Light']
                </error-path>
                <error-message>
                  Data already exists, cannot be created
                </error-message>
             </error>
          </errors>
       </edit>
    </edit-status>
  </yang-patch-status>
	    
 JSON Response from server:

 The following response is shown in JSON format to highlight the
 difference in the "error-path" object encoding. For JSON, the
 instance-identifier encoding in the "JSON Encoding of YANG
 Data" draft is used. The "error-path" string is wrapped for
 display purposes.

   HTTP/1.1 409 Conflict
   Date: Mon, 23 Apr 2012 13:01:20 GMT
   Server: example-server
   Last-Modified: Mon, 23 Apr 2012 13:01:20 GMT
   Content-Type: application/yang-data+json

   {
     "ietf-yang-patch:yang-patch-status" : {
       "patch-id" : "add-songs-patch",
       "edit-status" : {
         "edit" : [
           {
             "edit-id" : "edit1",
             "errors" : {
               "error" : [
                 {
                   "error-type": "application",
                   "error-tag": "data-exists",
                   "error-path": "/example-jukebox:jukebox/library
                      /artist[name='Foo Fighters']
                      /album[name='Wasting Light']
                      /song[name='Burning Light']",
                   "error-message":
                     "Data already exists, cannot be created"
                 }
               ]
             }
           }
         ]
       }
     }
   }
	    

D.1.2. Add Resources: Success

The following example shows several songs being added to an existing album.

 Request from client:

   PATCH /restconf/data/example-jukebox:jukebox/
      library/artist=Foo%20Fighters/album=Wasting%20Light
      HTTP/1.1
   Host: example.com
   Accept: application/yang-data+json
   Content-Type: application/yang-patch+json

   {
     "ietf-yang-patch:yang-patch" : {
       "patch-id" : "add-songs-patch-2",
       "edit" : [
         {
           "edit-id" : "edit1",
           "operation" : "create",
           "target" : "/song",
           "value" : {
             "song" : {
               "name" : "Rope",
               "location" : "/media/rope.mp3",
               "format" : "MP3",
               "length" : 259
             }
           }
         },
         {
           "edit-id" : "edit2",
           "operation" : "create",
           "target" : "/song",
           "value" : {
             "song" : {
               "name" : "Dear Rosemary",
               "location" : "/media/dear_rosemary.mp3",
               "format" : "MP3",
               "length" : 269
             }
           }
         }
       ]
     }
   }

 Response from server:

   HTTP/1.1 200 Success
   Date: Mon, 23 Apr 2012 13:01:20 GMT
   Server: example-server
   Last-Modified: Mon, 23 Apr 2012 13:01:20 GMT
   Content-Type: application/yang-data+json

   {
     "ietf-yang-patch:yang-patch-status" : {
       "patch-id" : "add-songs-patch-2",
       "ok" : [null]
     }
   }
	    

D.1.3. Move list entry example

The following example shows a song being moved within an existing playlist. Song "1" in playlist "Foo‑One" is being moved after song "3" in the playlist. The operation succeeds, so a non-error reply example can be shown.

 Request from client:

   PATCH /restconf/data/example-jukebox:jukebox/
     playlist=Foo-One   HTTP/1.1
   Host: example.com
   Accept: application/yang-data+json
   Content-Type: application/yang-patch+json

   {
     "ietf-yang-patch:yang-patch" : {
       "patch-id" : "move-song-patch",
       "comment" : "Move song 1 after song 3",
       "edit" : [
         {
           "edit-id" : "edit1",
           "operation" : "move",
           "target" : "/song/1",
           "point" : "/song3",
           "where" : "after"
         }
       ]
     }
   }

 Response from server:

   HTTP/1.1 400 OK
   Date: Mon, 23 Apr 2012 13:01:20 GMT
   Server: example-server
   Last-Modified: Mon, 23 Apr 2012 13:01:20 GMT
   Content-Type: application/yang-data+json

   {
     "ietf-restconf:yang-patch-status" : {
       "patch-id" : "move-song-patch",
       "ok" : [null]
     }
   }
	    

D.1.4. Edit datastore resource example

The following example shows how 3 top-level data nodes from different modules can be edited at the same time.

Example module "foo" defines leaf X. Example module "bar" defines container Y, with child leafs A and B. Example module "baz" defines list Z, with key C and child leafs D and E.

 Request from client:

   PATCH /restconf/data  HTTP/1.1
   Host: example.com
   Accept: application/yang-data+json
   Content-Type: application/yang-patch+json

   {
     "ietf-yang-patch:yang-patch" : {
       "patch-id" : "datastore-patch-1",
       "comment" : "Edit 3 top-level data nodes at once",
       "edit" : [
         {
           "edit-id" : "edit1",
           "operation" : "create",
           "target" : "/foo:X",
           "value" : {
             "foo:X" : 42
           }
         },
         {
           "edit-id" : "edit2",
           "operation" : "merge",
           "target" : "/bar:Y",
           "value" : {
             "bar:Y" : {
               "A" : "test1",
               "B" : 99
             }
           }
         },
         {
           "edit-id" : "edit3",
           "operation" : "replace",
           "target" : "/baz:Z=2",
           "value" : {
             "baz:Z" : {
               "C" : 2,
               "D" : 100,
               "E" : false
             }
           }
         }
       ]
     }
   }

 Response from server:

   HTTP/1.1 400 OK
   Date: Mon, 23 Apr 2012 13:02:20 GMT
   Server: example-server
   Last-Modified: Mon, 23 Apr 2012 13:01:20 GMT
   Content-Type: application/yang-data+json

   {
     "ietf-restconf:yang-patch-status" : {
       "patch-id" : "datastore-patch-1",
       "ok" : [null]
     }
   }
	    

Authors' Addresses

Andy Bierman YumaWorks EMail: andy@yumaworks.com
Martin Bjorklund Tail-f Systems EMail: mbj@tail-f.com
Kent Watsen Juniper Networks EMail: kwatsen@juniper.net