YumaWorks

andy@yumaworks.com

Tail-f Systems

mbj@tail-f.com

Juniper Networks

kwatsen@juniper.net

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

There is a need for standard mechanisms to patch datastores defined in , which contain conceptual data that conforms to schema specified with YANG . An "ordered edit list" approach is needed to provide RESTCONF client developers with more precise RESTCONF client control of the edit procedure than existing mechanisms found in . This document defines a media type for a YANG-based editing mechanism that can be used with the HTTP PATCH method . YANG Patch is designed to support the RESTCONF protocol, defined in . 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.

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, .

The following terms are defined in : configuration data datastore configuration datastore protocol operation running configuration datastore state data user

The following terms are defined in : header field message-body query request URI The following terms are defined in : method request resource

The following terms are defined in : container data node leaf leaf-list list RPC operation (now called protocol operation)

The following terms are defined in : application/yang-data+xml application/yang-data+json data resource datastore resource patch RESTCONF capability target resource YANG data template

The following terms are used within this document: RESTCONF client: a client which implements the RESTCONF protocol. RESTCONF server: a server which implements the RESTCONF protocol. YANG Patch: a conceptual edit request using the "yang‑patch" YANG Patch template, defined in . In HTTP, refers to a PATCH method where a representation uses either the media type "application/yang‑patch+xml" or "application/yang‑patch+json". YANG Patch Status: a conceptual edit status response using the YANG "yang‑patch‑status" YANG data template, defined in . In HTTP, refers to a response message for a PATCH method, where it has a representation with either the media type "application/yang‑data+xml" or "application/yang‑data+json". YANG Patch template: this is similar to a YANG data template, except it has a representation with the media type "application/yang‑patch+xml" or "application/yang‑patch+json".

Some protocol message lines within examples throughout the document are split into multiple lines for display purposes only. When a line ends with backslash ('\') as the last character, the line is wrapped for display purposes. It is to be considered to be joined to the next line by deleting the backslash, the following line break, and the leading whitespace of the next line.

A simplified graphical representation of the data model is used in this document. The meaning of the symbols in these diagrams is as follows: Brackets "[" and "]" enclose list keys. Abbreviations before data node names: "rw" means configuration data (read-write), "ro" state data (read-only), and "x" operation resource (executable) Symbols after data node names: "?" means an optional node and "*" denotes a "list" and "leaf‑list". Parentheses enclose choice and case nodes, and case nodes are also marked with a colon (":"). Ellipsis ("...") stands for contents of subtrees that are not shown.

A "YANG Patch" is an ordered list of edits that are applied to the target datastore by the RESTCONF server. The specific fields are defined in the YANG module in . The YANG Patch operation is invoked by the RESTCONF client by sending a PATCH method request with a representation using either the "application/yang‑patch+xml" or "application/yang‑patch+json" media type. A message-body representing the YANG Patch input parameters MUST be provided. YANG Patch has some features that are not possible with the PATCH method in RESTCONF: YANG Patch allows multiple sub-resources to be edited at within the same PATCH method. YANG Patch allows more precise edit operations than RESTCONF. There are 7 operations supported (create, delete, insert, merge, move, replace, remove). YANG Patch uses an edit list with an explicit processing order. The edits are processed in client-specified order, and error processing can be precise even when multiple errors occur in the same patch request. The YANG Patch "patch‑id" may be useful for debugging, and SHOULD be present in any audit audit logging records generated by the RESTCONF server for a patch. The RESTCONF server MUST return the Accept-Patch header field in an OPTIONS response, as specified in , which includes the media type for YANG Patch. Note that YANG Patch can only edit data resources. The PATCH method cannot be used to replace the datastore resource. Although the "ietf‑yang‑patch" YANG module is written using YANG version 1.1 , an implementation of YANG Patch can be used with content defined in YANG version 1 as well. Example:

A YANG Patch can be encoded in XML format according to . It can also be encoded in JSON, according to "JSON Encoding of Data Modeled with YANG" . If any meta-data needs to be sent in a JSON message, it is encoded according to "Defining and Using Metadata with YANG" .

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", to edit top-level configuration data resources, or it can be a configuration data resource within the datastore resource, e.g., "{+restconf}/data/ietf‑interfaces:interfaces", to edit sub-resources within a top-level configuration data resource. The target resource MUST identify exactly one resource instance. If more than one resource instance is identified, then the request MUST NOT be processed, and a "400 Bad Request" error response MUST be sent by the server. If the target resource does not identify any existing resource instance then the request MUST NOT be processed, and a "404 Not Found" error response MUST be sent by the server. Each edit with a YANG Patch identifies a target data node for the associated edit. This is described in .

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. The merge, replace, create, delete, and remove edit operations have the exact same meaning as defined for the "operation" attribute in section 7.2 of . Each edit within a YANG Patch MUST identify exactly one data resource instance. If an edit represents more than one resource instance, then the request MUST NOT be processed, and a "400 Bad Request" error response MUST be sent by the server. If the edit does not identify any existing resource instance, and the operation for the edit is not "create", then the request MUST NOT be processed, and a "404 Not Found" error response MUST be sent by the server. A "yang‑patch‑status" response MUST be sent by the server identifying the edit(s) that are not valid. YANG Patch does not provide any access to specific datastores. It is am implementation detail how a server processes an edit if it is co-located with a NETCONF server that does provide access to individual datastores. A complete datastore cannot be replaced in the same manner as provided by the "copy‑config" operation defined in section 7.3 of . Only the specified nodes in a YANG Patch are affected. A message-body representing the YANG Patch is sent by the RESTCONF 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

A message-body representing the YANG Patch Status is returned to the RESTCONF 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 . YANG tree diagram for "yang‑patch‑status" Container:

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.

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. 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

If a YANG Patch is completed without errors, the RESTCONF server SHOULD return a "yang‑patch‑status" message. The RESTCONF server will save the running datastore to non-volatile storage if it supports non-volatile storage, and if the running datastore contents have changed, as specified in . Refer to for a example of a successful YANG Patch response.

If a well-formed, schema-valid YANG Patch message is received, then the RESTCONF 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 RESTCONF server SHOULD return a "yang‑patch‑status" message. Refer to for a example of an error YANG Patch response.

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

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 RESTCONF server. The "ietf‑restconf" module from 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@2016-09-26.yang"

WG List: Author: Andy Bierman Author: Martin Bjorklund Author: Kent Watsen "; 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-12.txt // RFC Ed.: update the date below with the date of RFC publication // and remove this note. revision 2016-09-26 { 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; mandatory true; description "An arbitrary string provided by the client to identify the entire 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. The 'target' 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: some value 42 "; } } } } // 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 that are 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>

This document registers one URI as a namespace in the IETF XML registry . Following the format in RFC 3688, the following registration is requested to be made.

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

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

The YANG Patch media type does not introduce any significant new security threats, beyond what is described in . 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 RESTCONF 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 PATCH request MUST be applied atomically, as specified in section 2 of . A RESTCONF 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 RESTCONF server, which relies on the edit processing order mandated by YANG Patch. A RESTCONF server implementation SHOULD attempt to prevent system disruption due to excessive resource consumption required to fulfill YANG Patch edit requests. It may be possible to construct an attack on such a RESTCONF server, which attempts to consume all available memory or other resource types.

Harvard University In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document provides an overview of HTTP architecture and its associated terminology, defines the "http" and "https" Uniform Resource Identifier (URI) schemes, defines the HTTP/1.1 message syntax and parsing requirements, and describes related security concerns for implementations. The Hypertext Transfer Protocol (HTTP) is a stateless \%application- level protocol for distributed, collaborative, hypertext information systems. This document defines the semantics of HTTP/1.1 messages, as expressed by request methods, request header fields, response status codes, and response header fields, along with the payload of messages (metadata and body content) and mechanisms for content negotiation. This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas. Several applications extending the Hypertext Transfer Protocol (HTTP) require a feature to do partial resource modification. The existing HTTP PUT method only allows a complete replacement of a document. This proposal adds a new HTTP method, PATCH, to modify an existing HTTP resource. [STANDARDS-TRACK] YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS TRACK] YANG is a data modeling language used to model configuration data, state data, Remote Procedure Calls, and notifications for network management protocols. This document describes the syntax and semantics of version 1.1 of the YANG language. YANG version 1.1 is a maintenance release of the YANG language, addressing ambiguities and defects in the original specification. There are a small number of backward incompatibilities from YANG version 1. This document also specifies the YANG mappings to the Network Configuration Protocol (NETCONF). YumaWorks Tail-f Systems Juniper Networks This document defines encoding rules for representing configuration data, state data, parameters of Remote Procedure Call (RPC) operations or actions, and notifications defined using YANG as JavaScript Object Notation (JSON) text. This document defines a YANG extension that allows for defining metadata annotations in YANG modules. The document also specifies XML and JSON encoding of annotations and other rules for annotating instances of YANG data nodes. JavaScript Object Notation (JSON) is a lightweight, text-based, language-independent data interchange format. It was derived from the ECMAScript Programming Language Standard. JSON defines a small set of formatting rules for the portable representation of structured data. This document removes inconsistencies with other specifications of JSON, repairs specification errors, and offers experience-based interoperability guidance.

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).

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

clarify target resource must exist fix errors in some examples change application/yang-patch-xml to application/yang-patch+xml clarified some section titles clarified error responses for multiple edit instances made patch-id field mandatory referenced NETCONF operation attribute

change application/yang-patch to application/yang-patch-xml change server to RESTCONF server and remove NETCONF server term change client to RESTCONF client and remove NETCONF client term clarified that YANG 1.0 content can be used in a YANG Patch implementation clarified more terminology fixed missing keys in edit examples added insert list example

change yang-patch+xml to yang-patch clarify application/yang-patch+json media type add edit datastore example change data-resource-offset typedef so it is consistent for XML and JSON

change RFC 7158 reference to RFC 7159 reference change RFC 2616 reference to RFC 7230 reference remove unused HTTP terms remove import-by-revision of ietf-restconf; not needed change application/yang.patch media type to application/yang-patch remove application/yang.patch-status media type; use application/yang-data instead

clarified target datastore and target data node terms clarified that target leaf can be single forward slash '/' added Successful edit response handling section clarified that YANG Patch draft is for RESTCONF protocol only but may be defined for other protocols outside this document clarified that YANG Patch draft is for configuration datastores only but may be defined for other datastore types outside this document fixed typos

converted YANG module to YANG 1.1 changed anyxml value to anydata value updated import revision date for ietf-restconf updated revision date for ietf-yang-patch because import-by-revision date needed to be changed

changed errors example so a full request and error response is shown in XML format fixed error-path to match instance-identifier encoding for both XML and JSON added references for YANG to JSON and YANG Metadata drafts clarified that YANG JSON drafts are used for encoding, not plain JSON

updated reference to RESTCONF

removed NETCONF specific text changed data-resource-offset typedef from a relative URI to an XPath absolute path expression clarified insert operation removed requirement that edits MUST be applied in ascending order change SHOULD keep datastore unchanged on error to MUST (this is required by HTTP PATCH) removed length restriction on 'comment' leaf updated YANG tree for example-jukebox library

added usage of restconf-media-type extension to map the yang-patch and yang-patch-status groupings to media types added yang-patch RESTCONF capability URI Added sub-section for terms used from RESTCONF filled in security considerations section

Reversed order of change log Clarified anyxml structure of "value" parameter within a YANG patch request (github issue #1) Updated RESTCONF reference Added note to open issues section to check github instead

Added text requiring support for Accept-Patch header field, and removed 'Identification of YANG Patch capabilities' open issue. Removed 'location' leaf from yang-patch-status grouping Removed open issue 'Protocol independence' because the location leaf was removed. Removed open issue 'RESTCONF coupling' because there is no concern about a normative reference to RESTCONF. There may need to be a YANG 1.1 mechanism to allow protocol template usage (instead of grouping wrapper). Removed open issue 'Is the delete operation needed'. It was decided that both delete and remove should remain as operations and clients can choose which one to use. This is not an implementation burden on the server. Removed open issue 'global-errors needed'. It was decided that they are needed as defined because the global <ok/> is needed and the special key value for edit=global error only allows for 1 global error. Removed open issue 'Is location leaf needed'. It was decided that it is not needed so this leaf has been removed. Removed open issue 'Bulk editing support in yang-patch-status'. The 'location' leaf has been removed so this issue is no longer applicable. Removed open issue 'Edit list mechanism'. Added text to the 'edit' list description-stmt about how the individual edits must be processed. There is no concern about duplicate edits which cause intermediate results to be altered by subsequent edits in the same edit list.

Created open issues section

Refer to the github issue tracker for any open issues:

The example YANG module used in this document represents a simple media jukebox interface. The "example‑jukebox" YANG module is defined in . YANG tree diagram for "example‑jukebox" Module:

This section includes RESTCONF examples. Most examples are shown in JSON encoding , and some are shown in XML encoding .

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 the RESTCONF client:

add-songs-patch edit1 create /song=Bridge%20Burning Bridge Burning /media/bridge_burning.mp3 MP3 288 edit2 create /song=Rope Rope /media/rope.mp3 MP3 259 edit3 create /song=Dear%20Rosemary Dear Rosemary /media/dear_rosemary.mp3 MP3 269 ]]>

XML Response from the RESTCONF server:

add-songs-patch edit1 application data-exists /jb:jukebox/jb:library /jb:artist[jb:name='Foo Fighters'] /jb:album[jb:name='Wasting Light'] /jb:song[jb:name='Burning Light'] Data already exists, cannot be created ]]>

JSON Response from the RESTCONF 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 following example shows several songs being added to an existing album. Each of 2 edits contains one song. Both edits succeed and new sub-resources are created Request from the RESTCONF client:

Response from the RESTCONF server:

The following example shows a song being inserted within an existing playlist. Song "6" in playlist "Foo‑One" is being inserted after song "5" in the playlist. The operation succeeds, so a non-error reply example can be shown.

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. Note that no "value" parameter is needed for a "move" operation. The operation succeeds, so a non-error reply example can be shown. Request from the RESTCONF client:

Response from the RESTCONF server:

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 the RESTCONF client:

Response from the RESTCONF server: