Network Working Group                                         A. BiermanInternet-Draft                                                 YumaWorksIntended status: Standards Track                            M. BjorklundExpires: February 16, 2017                                Tail-f Systems                                                               K. Watsen                                                        Juniper Networks                                                         August 15, 2016                           RESTCONF Protocol                     draft-ietf-netconf-restconf-16Abstract   This document describes an HTTP-based protocol that provides a   programmatic interface for accessing data defined in YANG, using the   datastore concepts defined in NETCONF.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 February 16, 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 ofBierman, et al.         Expires February 16, 2017               [Page 1]Internet-Draft                  RESTCONF                     August 2016   the Trust Legal Provisions and are provided without warranty as   described in the Simplified BSD License.Table of Contents   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   5     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   6       1.1.1.  NETCONF . . . . . . . . . . . . . . . . . . . . . . .   6       1.1.2.  HTTP  . . . . . . . . . . . . . . . . . . . . . . . .   6       1.1.3.  YANG  . . . . . . . . . . . . . . . . . . . . . . . .   7       1.1.4.  NETCONF Notifications . . . . . . . . . . . . . . . .   7       1.1.5.  Terms . . . . . . . . . . . . . . . . . . . . . . . .   8       1.1.6.  URI Template and Examples . . . . . . . . . . . . . .  10       1.1.7.  Tree Diagrams . . . . . . . . . . . . . . . . . . . .  10     1.2.  Subset of NETCONF Functionality . . . . . . . . . . . . .  11     1.3.  Data Model Driven API . . . . . . . . . . . . . . . . . .  12     1.4.  Coexistence with NETCONF  . . . . . . . . . . . . . . . .  13     1.5.  RESTCONF Extensibility  . . . . . . . . . . . . . . . . .  14   2.  Transport Protocol Requirements . . . . . . . . . . . . . . .  15     2.1.  Integrity and Confidentiality . . . . . . . . . . . . . .  15     2.2.  HTTPS with X.509v3 Certificates . . . . . . . . . . . . .  15     2.3.  Certificate Validation  . . . . . . . . . . . . . . . . .  15     2.4.  Authenticated Server Identity . . . . . . . . . . . . . .  16     2.5.  Authenticated Client Identity . . . . . . . . . . . . . .  16   3.  Resources . . . . . . . . . . . . . . . . . . . . . . . . . .  16     3.1.  Root Resource Discovery . . . . . . . . . . . . . . . . .  17     3.2.  RESTCONF Media Types  . . . . . . . . . . . . . . . . . .  19     3.3.  API Resource  . . . . . . . . . . . . . . . . . . . . . .  19       3.3.1.  {+restconf}/data  . . . . . . . . . . . . . . . . . .  20       3.3.2.  {+restconf}/operations  . . . . . . . . . . . . . . .  20       3.3.3.  {+restconf}/yang-library-version  . . . . . . . . . .  21     3.4.  Datastore Resource  . . . . . . . . . . . . . . . . . . .  21       3.4.1.  Edit Collision Prevention . . . . . . . . . . . . . .  22     3.5.  Data Resource . . . . . . . . . . . . . . . . . . . . . .  23       3.5.1.  Timestamp . . . . . . . . . . . . . . . . . . . . . .  24       3.5.2.  Entity-Tag  . . . . . . . . . . . . . . . . . . . . .  24       3.5.3.  Encoding Data Resource Identifiers in the Request URI  24       3.5.4.  Default Handling  . . . . . . . . . . . . . . . . . .  28     3.6.  Operation Resource  . . . . . . . . . . . . . . . . . . .  29       3.6.1.  Encoding Operation Resource Input Parameters  . . . .  30       3.6.2.  Encoding Operation Resource Output Parameters . . . .  34       3.6.3.  Encoding Operation Resource Errors  . . . . . . . . .  36     3.7.  Schema Resource . . . . . . . . . . . . . . . . . . . . .  37     3.8.  Event Stream Resource . . . . . . . . . . . . . . . . . .  38     3.9.  Errors YANG Data Template . . . . . . . . . . . . . . . .  39   4.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .  39     4.1.  OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . .  40     4.2.  HEAD  . . . . . . . . . . . . . . . . . . . . . . . . . .  40Bierman, et al.         Expires February 16, 2017               [Page 2]Internet-Draft                  RESTCONF                     August 2016     4.3.  GET . . . . . . . . . . . . . . . . . . . . . . . . . . .  41     4.4.  POST  . . . . . . . . . . . . . . . . . . . . . . . . . .  42       4.4.1.  Create Resource Mode  . . . . . . . . . . . . . . . .  43       4.4.2.  Invoke Operation Mode . . . . . . . . . . . . . . . .  44     4.5.  PUT . . . . . . . . . . . . . . . . . . . . . . . . . . .  45     4.6.  PATCH . . . . . . . . . . . . . . . . . . . . . . . . . .  47       4.6.1.  Plain Patch . . . . . . . . . . . . . . . . . . . . .  47     4.7.  DELETE  . . . . . . . . . . . . . . . . . . . . . . . . .  48     4.8.  Query Parameters  . . . . . . . . . . . . . . . . . . . .  49       4.8.1.  The "content" Query Parameter . . . . . . . . . . . .  50       4.8.2.  The "depth" Query Parameter . . . . . . . . . . . . .  51       4.8.3.  The "fields" Query Parameter  . . . . . . . . . . . .  52       4.8.4.  The "filter" Query Parameter  . . . . . . . . . . . .  53       4.8.5.  The "insert" Query Parameter  . . . . . . . . . . . .  53       4.8.6.  The "point" Query Parameter . . . . . . . . . . . . .  54       4.8.7.  The "start-time" Query Parameter  . . . . . . . . . .  55       4.8.8.  The "stop-time" Query Parameter . . . . . . . . . . .  55       4.8.9.  The "with-defaults" Query Parameter . . . . . . . . .  56   5.  Messages  . . . . . . . . . . . . . . . . . . . . . . . . . .  57     5.1.  Request URI Structure . . . . . . . . . . . . . . . . . .  57     5.2.  Message Encoding  . . . . . . . . . . . . . . . . . . . .  59     5.3.  RESTCONF Metadata . . . . . . . . . . . . . . . . . . . .  60       5.3.1.  XML Metadata Encoding Example . . . . . . . . . . . .  60       5.3.2.  JSON Metadata Encoding Example  . . . . . . . . . . .  60     5.4.  Return Status . . . . . . . . . . . . . . . . . . . . . .  61     5.5.  Message Caching . . . . . . . . . . . . . . . . . . . . .  61   6.  Notifications . . . . . . . . . . . . . . . . . . . . . . . .  62     6.1.  Server Support  . . . . . . . . . . . . . . . . . . . . .  62     6.2.  Event Streams . . . . . . . . . . . . . . . . . . . . . .  62     6.3.  Subscribing to Receive Notifications  . . . . . . . . . .  64       6.3.1.  NETCONF Event Stream  . . . . . . . . . . . . . . . .  65     6.4.  Receiving Event Notifications . . . . . . . . . . . . . .  65   7.  Error Reporting . . . . . . . . . . . . . . . . . . . . . . .  67     7.1.  Error Response Message  . . . . . . . . . . . . . . . . .  68   8.  RESTCONF Module . . . . . . . . . . . . . . . . . . . . . . .  70   9.  RESTCONF Monitoring . . . . . . . . . . . . . . . . . . . . .  77     9.1.  restconf-state/capabilities . . . . . . . . . . . . . . .  77       9.1.1.  Query Parameter URIs  . . . . . . . . . . . . . . . .  78       9.1.2.  The "defaults" Protocol Capability URI  . . . . . . .  78     9.2.  restconf-state/streams  . . . . . . . . . . . . . . . . .  79     9.3.  RESTCONF Monitoring Module  . . . . . . . . . . . . . . .  79   10. YANG Module Library . . . . . . . . . . . . . . . . . . . . .  83     10.1.  modules-state/module . . . . . . . . . . . . . . . . . .  83   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  83     11.1.  The "restconf" Relation Type . . . . . . . . . . . . . .  84     11.2.  YANG Module Registry . . . . . . . . . . . . . . . . . .  84     11.3.  Media Types  . . . . . . . . . . . . . . . . . . . . . .  85       11.3.1.  Media Type application/yang-data-xml . . . . . . . .  85Bierman, et al.         Expires February 16, 2017               [Page 3]Internet-Draft                  RESTCONF                     August 2016       11.3.2.  Media Type application/yang-data+json  . . . . . . .  86     11.4.  RESTCONF Capability URNs . . . . . . . . . . . . . . . .  88   12. Security Considerations . . . . . . . . . . . . . . . . . . .  89   13. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  90   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  91     14.1.  Normative References . . . . . . . . . . . . . . . . . .  91     14.2.  Informative References . . . . . . . . . . . . . . . . .  94   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  94     A.1.  v15 to v16  . . . . . . . . . . . . . . . . . . . . . . .  94     A.2.  v14 to v15  . . . . . . . . . . . . . . . . . . . . . . .  94     A.3.  v13 - v14 . . . . . . . . . . . . . . . . . . . . . . . .  95     A.4.  v12 - v13 . . . . . . . . . . . . . . . . . . . . . . . .  97     A.5.  v11 - v12 . . . . . . . . . . . . . . . . . . . . . . . .  97     A.6.  v10 - v11 . . . . . . . . . . . . . . . . . . . . . . . .  97     A.7.  v09 - v10 . . . . . . . . . . . . . . . . . . . . . . . .  98     A.8.  v08 - v09 . . . . . . . . . . . . . . . . . . . . . . . . 100     A.9.  v07 - v08 . . . . . . . . . . . . . . . . . . . . . . . . 100     A.10. v06 - v07 . . . . . . . . . . . . . . . . . . . . . . . . 101     A.11. v05 - v06 . . . . . . . . . . . . . . . . . . . . . . . . 101     A.12. v04 - v05 . . . . . . . . . . . . . . . . . . . . . . . . 101     A.13. v03 - v04 . . . . . . . . . . . . . . . . . . . . . . . . 102     A.14. v02 - v03 . . . . . . . . . . . . . . . . . . . . . . . . 103     A.15. v01 - v02 . . . . . . . . . . . . . . . . . . . . . . . . 103     A.16. v00 - v01 . . . . . . . . . . . . . . . . . . . . . . . . 104     A.17. bierman:restconf-04 to ietf:restconf-00 . . . . . . . . . 105   Appendix B.  Open Issues  . . . . . . . . . . . . . . . . . . . . 105   Appendix C.  Example YANG Module  . . . . . . . . . . . . . . . . 105     C.1.  example-jukebox YANG Module . . . . . . . . . . . . . . . 106   Appendix D.  RESTCONF Message Examples  . . . . . . . . . . . . . 111     D.1.  Resource Retrieval Examples . . . . . . . . . . . . . . . 112       D.1.1.  Retrieve the Top-level API Resource . . . . . . . . . 112       D.1.2.  Retrieve The Server Module Information  . . . . . . . 113       D.1.3.  Retrieve The Server Capability Information  . . . . . 115     D.2.  Edit Resource Examples  . . . . . . . . . . . . . . . . . 116       D.2.1.  Create New Data Resources . . . . . . . . . . . . . . 116       D.2.2.  Detect Resource Entity-Tag Change . . . . . . . . . . 118       D.2.3.  Edit a Datastore Resource . . . . . . . . . . . . . . 118       D.2.4.  Edit a Data Resource  . . . . . . . . . . . . . . . . 119     D.3.  Query Parameter Examples  . . . . . . . . . . . . . . . . 120       D.3.1.  "content" Parameter . . . . . . . . . . . . . . . . . 120       D.3.2.  "depth" Parameter . . . . . . . . . . . . . . . . . . 123       D.3.3.  "fields" Parameter  . . . . . . . . . . . . . . . . . 126       D.3.4.  "insert" Parameter  . . . . . . . . . . . . . . . . . 127       D.3.5.  "point" Parameter . . . . . . . . . . . . . . . . . . 128       D.3.6.  "filter" Parameter  . . . . . . . . . . . . . . . . . 129       D.3.7.  "start-time" Parameter  . . . . . . . . . . . . . . . 130       D.3.8.  "stop-time" Parameter . . . . . . . . . . . . . . . . 130       D.3.9.  "with-defaults" Parameter . . . . . . . . . . . . . . 131Bierman, et al.         Expires February 16, 2017               [Page 4]Internet-Draft                  RESTCONF                     August 2016   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . 1321.  Introduction   There is a need for standard mechanisms to allow Web applications to   access the configuration data, state data, data-model-specific RPC   operations, and event notifications within a networking device, in a   modular and extensible manner.   This document defines an HTTP [RFC7230] based protocol called   RESTCONF, for configuring data defined in YANG version 1 [RFC6020] or   YANG version 1.1 [I-D.ietf-netmod-rfc6020bis], using the datastore   concepts defined in NETCONF [RFC6241].   NETCONF defines configuration datastores and a set of Create,   Retrieve, Update, Delete (CRUD) operations that can be used to access   these datastores.  NETCONF also defines a protocol for invoking these   operations.  The YANG language defines the syntax and semantics of   datastore content, configuration, state data, RPC operations, and   event notifications.   RESTCONF uses HTTP methods to provide CRUD operations on a conceptual   datastore containing YANG-defined data, which is compatible with a   server which implements NETCONF datastores.   If a RESTCONF server is co-located with a NETCONF server, then there   are protocol interactions with the NETCONF protocol, which are   described in Section 1.4.  The RESTCONF server MAY provide access to   specific datastores using operation resources, as described in   Section 3.6.  The RESTCONF protocol does not specify any mandatory   operation resources.  The semantics of each operation resource   determine if and how datastores are accessed.   Configuration data and state data are exposed as resources that can   be retrieved with the GET method.  Resources representing   configuration data can be modified with the DELETE, PATCH, POST, and   PUT methods.  Data is encoded with either XML [W3C.REC-xml-20081126]   or JSON [RFC7159].   Data-model-specific RPC operations defined with the YANG "rpc" or   "action" statements can be invoked with the POST method.  Data-model-   specific event notifications defined with the YANG "notification"   statement can be accessed.Bierman, et al.         Expires February 16, 2017               [Page 5]Internet-Draft                  RESTCONF                     August 20161.1.  Terminology   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this   document are to be interpreted as described in [RFC2119].1.1.1.  NETCONF   The following terms are defined in [RFC6241]:   o  candidate configuration datastore   o  configuration data   o  datastore   o  configuration datastore   o  running configuration datastore   o  startup configuration datastore   o  state data   o  user1.1.2.  HTTP   The following terms are defined in [RFC3986]:   o  fragment   o  path   o  query   The following terms are defined in [RFC7230]:   o  header field   o  message-body   o  request-line   o  request URI   o  status-lineBierman, et al.         Expires February 16, 2017               [Page 6]Internet-Draft                  RESTCONF                     August 2016   The following terms are defined in [RFC7231]:   o  method   o  request   o  resource   The following terms are defined in [RFC7232]:   o  entity-tag1.1.3.  YANG   The following terms are defined in [I-D.ietf-netmod-rfc6020bis]:   o  action   o  container   o  data node   o  key leaf   o  leaf   o  leaf-list   o  list   o  mandatory node   o  ordered-by user   o  presence container   o  RPC operation   o  top-level data node1.1.4.  NETCONF Notifications   The following terms are defined in [RFC5277]:   o  notification replayBierman, et al.         Expires February 16, 2017               [Page 7]Internet-Draft                  RESTCONF                     August 20161.1.5.  Terms   The following terms are used within this document:   o  API resource: the resource that models the RESTCONF root resource      and the sub-resources to access YANG-defined content.  It is      defined with the YANG data template named "yang-api" in the      "ietf-restconf" module.   o  client: a RESTCONF client   o  data resource: a resource that models a YANG data node.  It is      defined with YANG data definition statements.   o  datastore resource: the resource that models a programmatic      interface using NETCONF datastore concepts.  By default, RESTCONF      methods access a unified view of the underlying datastore      implementation on the server.  It is defined as a sub-resource      within the API resource.   o  edit operation: a RESTCONF operation on a data resource using      either a POST, PUT, PATCH, or DELETE method.  This is not the same      as the NETCONF edit operation (i.e., one of the values for the      "nc:operation" attribute: "create", "replace", "merge", "delete",      or "remove").   o  event stream resource: This resource represents an SSE (Server-      Sent Events) event stream.  The content consists of text using the      media type "text/event-stream", as defined by the SSE      [W3C.REC-eventsource-20150203] specification.  Event stream      contents are described in Section 3.8.   o  media-type: HTTP uses Internet media types [RFC2046] in the      Content-Type and Accept header fields in order to provide open and      extensible data typing and type negotiation.   o  NETCONF client: a client which implements the NETCONF protocol.      Called "client" in [RFC6241].   o  NETCONF server: a server which implements the NETCONF protocol.      Called "server" in [RFC6241].   o  operation: the conceptual RESTCONF operation for a message,      derived from the HTTP method, request URI, header fields, and      message-body.Bierman, et al.         Expires February 16, 2017               [Page 8]Internet-Draft                  RESTCONF                     August 2016   o  operation resource: a resource that models a data-model-specific      operation, that is defined with a YANG "rpc" or "action"      statement.  It is invoked with the POST method.   o  patch: a PATCH method on the target datastore or data resource.      The media type of the message-body content will identify the patch      type in use.   o  plain patch: a specific media type for use with the PATCH method,      defined in Section 4.6.1, that can be used for simple merge      operations.  It is specified by a request Content-Type of      "application/yang-data-xml" or "application/yang-data+json".   o  query parameter: a parameter (and its value if any), encoded      within the query component of the request URI.   o  resource type: one of the RESTCONF resource classes defined in      this document.  One of "api", "datastore", "data", "operation",      "schema", or "event stream".   o  RESTCONF capability: An optional RESTCONF protocol feature      supported by the server, which is identified by an IANA registered      NETCONF Capability URI, and advertised with an entry in the      "capability" leaf-list defined in Section 9.3.   o  RESTCONF client: a client which implements the RESTCONF protocol.   o  RESTCONF server: a server which implements the RESTCONF protocol.   o  retrieval request: a request using the GET or HEAD methods.   o  schema resource: a resource that used by the client to retrieve a      YANG schema with the GET method.  It has a representation with the      media type "application/yang".   o  server: a RESTCONF server   o  stream list: the set of data resource instances that describe the      event stream resources available from the server.  This      information is defined in the "ietf-restconf-monitoring" module as      the "stream" list.  It can be retrieved using the target resource      "{+restconf}/data/ietf-restconf-monitoring:restconf-state/streams/      stream".  The stream list contains information about each stream,      such as the URL to retrieve the event stream data.   o  stream resource: An event stream resource.Bierman, et al.         Expires February 16, 2017               [Page 9]Internet-Draft                  RESTCONF                     August 2016   o  target resource: the resource that is associated with a particular      message, identified by the "path" component of the request URI.   o  yang-data extension: A YANG external statement that conforms to      the "yang-data" extension statement found in Section 8.  The yang-      data extension is used to define YANG data structures that are      meant to be used as YANG data templates.  These data structures      are not intended to be implemented as part of a configuration      datastore or as operational state within the server, so normal      YANG data definition statements cannot be used.   o  YANG data template: a schema for modeling protocol message      components as conceptual data structure using YANG.  This allows      the messages to be defined in an encoding-independent manner.      Each YANG data template is defined with the "yang-data" extension,      found in Section 8.  Representations of instances conforming to a      particular YANG data template can be defined for YANG.  The XML      representation is defined in YANG version 1.1      [I-D.ietf-netmod-rfc6020bis], and supported with the "application/      yang-data-xml" media type.  The JSON representation is defined in      JSON Encoding of Data Modeled with YANG      [I-D.ietf-netmod-yang-json], and supported with the "application/      yang-data+json" media type.1.1.6.  URI Template and Examples   Throughout this document, the URI template [RFC6570] syntax   "{+restconf}" is used to refer to the RESTCONF root resource outside   of an example.  See Section 3.1 for details.   For simplicity, all of the examples in this document use "/restconf"   as the discovered RESTCONF API root path.  Many of the examples   throughout the document are based on the "example-jukebox" YANG   module, defined in Appendix C.1.   Many protocol header lines and message-body text 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.1.1.7.  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:Bierman, et al.         Expires February 16, 2017              [Page 10]Internet-Draft                  RESTCONF                     August 2016   o  Brackets "[" and "]" enclose list keys.   o  Abbreviations before data node names: "rw" means configuration      data (read-write), "ro" state data (read-only), and "x" operation      resource (executable)   o  Symbols after data node names: "?" means an optional node, "!"      means a presence container, and "*" denotes a list and leaf-list.   o  Parentheses enclose choice and case nodes, and case nodes are also      marked with a colon (":").   o  Ellipsis ("...") stands for contents of subtrees that are not      shown.1.2.  Subset of NETCONF Functionality   RESTCONF does not need to mirror the full functionality of the   NETCONF protocol, but it does need to be compatible with NETCONF.   RESTCONF achieves this by implementing a subset of the interaction   capabilities provided by the NETCONF protocol, for instance, by   eliminating datastores and explicit locking.   RESTCONF uses HTTP methods to implement the equivalent of NETCONF   operations, enabling basic CRUD operations on a hierarchy of   conceptual resources.   The HTTP POST, PUT, PATCH, and DELETE methods are used to edit data   resources represented by YANG data models.  These basic edit   operations allow the running configuration to be altered by a   RESTCONF client.   RESTCONF is not intended to replace NETCONF, but rather provide an   HTTP interface that follows Representational State Transfer (REST)   principles [rest-dissertation], and is compatible with the NETCONF   datastore model.   The following figure shows the system components if a RESTCONF server   is co-located with a NETCONF server:Bierman, et al.         Expires February 16, 2017              [Page 11]Internet-Draft                  RESTCONF                     August 2016         +-----------+           +-----------------+         |  Web app  | <-------> |                 |         +-----------+  RESTCONF | network device  |                                 |                 |         +-----------+           |   +-----------+ |         | NETCONF   | <-------> |   | datastore | |         | Client    |  NETCONF  |   |           | |         +-----------+           |   +-----------+ |                                 +-----------------+   The following figure shows the system components if a RESTCONF server   is implemented in a device that does not have a NETCONF server:         +-----------+           +-----------------+         |  Web app  | <-------> |                 |         +-----------+  RESTCONF | network device  |                                 |                 |                                 +-----------------+   Note that there are no interactions at all between the NETCONF   protocol and RESTCONF protocol.  It is possible that locks are in use   on a RESTCONF server, even though RESTCONF cannot manipulate locks.   In such a case, the RESTCONF protocol will not be granted write   access to data resources within a datastore.1.3.  Data Model Driven API   RESTCONF combines the simplicity of the HTTP protocol with the   predictability and automation potential of a schema-driven API.   Knowing the YANG modules used by the server, a client can derive all   management resource URLs and the proper structure of all RESTCONF   requests and responses.  This strategy obviates the need for   responses provided by the server to contain Hypermedia as the Engine   of Application State (HATEOAS) links, originally described in Roy   Fielding's doctoral dissertation [rest-dissertation], because the   client can determine the links it needs from the YANG modules.   RESTCONF utilizes the YANG Library [RFC7895] to allow a client to   discover the YANG module conformance information for the server, in   case the client wants to use it.   The server can optionally support retrieval of the YANG modules it   uses, as identified in its YANG library.  See Section 3.7 for   details.   The URIs for data-model-specific RPC operations and datastore content   are predictable, based on the YANG module definitions.Bierman, et al.         Expires February 16, 2017              [Page 12]Internet-Draft                  RESTCONF                     August 2016   The RESTCONF protocol operates on a conceptual datastore defined with   the YANG data modeling language.  The server lists each YANG module   it supports using the "ietf-yang-library" YANG module, defined in   [RFC7895].  The server MUST implement the "ietf-yang-library" module,   which MUST identify all the YANG modules used by the server, in the   "modules-state/module" list.  The conceptual datastore contents,   data-model-specific RPC operations and event notifications are   identified by this set of YANG modules.   The classification of data as configuration or non-configuration is   derived from the YANG "config" statement.  Data ordering behavior is   derived from the YANG "ordered-by" statement.  Non-configuration data   is also called "state data".   The RESTCONF datastore editing model is simple and direct, similar to   the behavior of the :writable-running capability in NETCONF.  Each   RESTCONF edit of a data resource within the datastore resource is   activated upon successful completion of the edit.1.4.  Coexistence with NETCONF   RESTCONF can be implemented on a device that supports the NETCONF   protocol.   If the NETCONF server supports :writable-running, all edits to   configuration nodes in {+restconf}/data are performed in the running   configuration datastore.  The URI template "{+restconf}" is defined   in Section 1.1.6.   Otherwise, if the device supports :candidate, all edits to   configuration nodes in {+restconf}/data are performed in the   candidate configuration datastore.  The candidate MUST be   automatically committed to running immediately after each successful   edit.  Any edits from other sources that are in the candidate   datastore will also be committed.  If a confirmed commit procedure is   in progress by any NETCONF client, then this commit will act as the   confirming commit.  If the NETCONF server is expecting a "persist-id"   parameter to complete the confirmed commit procedure then the   RESTCONF edit operation MUST fail with a "409 Conflict" status-line.   There error-tag "in-use" is returned in this case.  The error-tag   value "resource-denied" is used in this case.   If the NETCONF server supports :startup, the RESTCONF server MUST   automatically update the non-volatile startup configuration   datastore, after the running datastore has been altered as a   consequence of a RESTCONF edit operation.Bierman, et al.         Expires February 16, 2017              [Page 13]Internet-Draft                  RESTCONF                     August 2016   If a datastore that would be modified by a RESTCONF operation has an   active lock from a NETCONF client, the RESTCONF edit operation MUST   fail with a "409 Conflict" status-line.  There error-tag "in-use" is   returned in this case.1.5.  RESTCONF Extensibility   There are two extensibility mechanisms built into RESTCONF:   o  protocol version   o  optional capabilities   This document defines version 1 of the RESTCONF protocol.  If a   future version of this protocol is defined, then that document will   specify how the new version of RESTCONF is identified.  It is   expected that a different RESTCONF root resource will be used which   will be located using a different link relation (See Section 3.1).   The server will advertise all protocol versions that it supports in   its host-meta data.   In this example, the server supports both RESTCONF version 1 and a   fictitious version 2.   The client might send:      GET /.well-known/host-meta HTTP/1.1      Host: example.com      Accept: application/xrd+xml   The server might respond:      HTTP/1.1 200 OK      Content-Type: application/xrd+xml      Content-Length: nnn      <XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0'>          <Link rel='restconf' href='/restconf'/>          <Link rel='restconf2' href='/restconf2'/>      </XRD>   RESTCONF also supports a server-defined list of optional   capabilities, which are listed by a server using the   "ietf-restconf-monitoring" module defined in Section 9.3.  This   document defines several query parameters in Section 4.8.  Each   optional parameter has a corresponding capability URI defined in   Section 9.1.1 that is advertised by the server if supported.Bierman, et al.         Expires February 16, 2017              [Page 14]Internet-Draft                  RESTCONF                     August 2016   The "capabilities" list can identify any sort of server extension.   Currently this extension mechanism is used to identify optional query   parameters that are supported, but it is not limited to that purpose.   For example, the "defaults" URI defined in Section 9.1.2 specifies a   mandatory URI identifying server defaults handling behavior.   A new sub-resource type could be identified with a capability if it   is optional to implement.  Mandatory protocol features and new   resource types require a new revision of the RESTCONF protocol.2.  Transport Protocol Requirements2.1.  Integrity and Confidentiality   HTTP [RFC7230] is an application layer protocol that may be layered   on any reliable transport-layer protocol.  RESTCONF is defined on top   of HTTP, but due to the sensitive nature of the information conveyed,   RESTCONF requires that the transport-layer protocol provides both   data integrity and confidentiality.  A RESTCONF server MUST support   the TLS protocol [RFC5246].  The RESTCONF protocol MUST NOT be used   over HTTP without using the TLS protocol.   HTTP/2 [RFC7540] MAY be used for RESTCONF.  The server MUST respond   using a single HTTP/2 stream for all client requests from a stream.   The server MAY respond using same HTTP/2 stream that was used for the   corresponding request.2.2.  HTTPS with X.509v3 Certificates   Given the nearly ubiquitous support for HTTP over TLS [RFC7230],   RESTCONF implementations MUST support the "https" URI scheme, which   has the IANA assigned default port 443.   RESTCONF servers MUST present an X.509v3 based certificate when   establishing a TLS connection with a RESTCONF client.  The use of   X.509v3 based certificates is consistent with NETCONF over TLS   [RFC7589].2.3.  Certificate Validation   The RESTCONF client MUST either use X.509 certificate path validation   [RFC5280] to verify the integrity of the RESTCONF server's TLS   certificate, or match the server's TLS certificate with a certificate   obtained by a trusted mechanism (e.g. a pinned certificate).  If   X.509 certificate path validation fails, and the presented X.509   certificate does not match a certificate obtained by a trusted   mechanism, the connection MUST be terminated, as described in   Section 7.2.1 of [RFC5246].Bierman, et al.         Expires February 16, 2017              [Page 15]Internet-Draft                  RESTCONF                     August 20162.4.  Authenticated Server Identity   The RESTCONF client MUST check the identity of the server according   to Section 6 of [RFC6125], including processing the outcome as   described in Section 6.6 of [RFC6125].2.5.  Authenticated Client Identity   The RESTCONF server MUST authenticate client access to any protected   resource.  If the RESTCONF client is not authenticated, the server   SHOULD send an HTTP response with "401 Unauthorized" status-line, as   defined in Section 3.1 of [RFC7235].  The error-tag value   "access-denied" is used in this case.   To authenticate a client, a RESTCONF server MUST use TLS based client   certificates (Section 7.4.6 of [RFC5246]), or MUST use any HTTP   authentication scheme defined in the HTTP Authentication Scheme   Registry (Section 5.1 in [RFC7235]).  A server MAY also support the   combination of both client certificates and an HTTP client   authentication scheme, with the determination of how to process this   combination left as an implementation decision.   The RESTCONF client identity derived from the authentication   mechanism used is hereafter known as the "RESTCONF username" and   subject to the NETCONF Access Control Module (NACM) [RFC6536].  When   a client certificate is presented, the RESTCONF username MUST be   derived using the algorithm defined in Section 7 of [RFC7589].  For   all other cases, when HTTP authentication is used, the RESTCONF   username MUST be provided by the HTTP authentication scheme used.3.  Resources   The RESTCONF protocol operates on a hierarchy of resources, starting   with the top-level API resource itself (Section 3.1).  Each resource   represents a manageable component within the device.   A resource can be considered as a collection of data and the set of   allowed methods on that data.  It can contain nested child resources.   The child resource types and methods allowed on them are data-model-   specific.   A resource has a representation associated with a media type   identifier, as represented by the "Content-Type" header field in the   HTTP response message.  A resource has one or more representations,   each associated with a different media type.  When a representation   of a resource is sent in an HTTP message, the associated media type   is given in the "Content-Type" header.  A resource can contain zero   or more nested resources.  A resource can be created and deletedBierman, et al.         Expires February 16, 2017              [Page 16]Internet-Draft                  RESTCONF                     August 2016   independently of its parent resource, as long as the parent resource   exists.   The RESTCONF resources are accessed via a set of URIs defined in this   document.  The set of YANG modules supported by the server will   determine the data model specific RPC operations, top-level data   nodes, and event notification messages supported by the server.   The RESTCONF protocol does not include a data resource discovery   mechanism.  Instead, the definitions within the YANG modules   advertised by the server are used to construct an RPC operation or   data resource identifier.3.1.  Root Resource Discovery   In line with the best practices defined by [RFC7320], RESTCONF   enables deployments to specify where the RESTCONF API is located.   When first connecting to a RESTCONF server, a RESTCONF client MUST   determine the root of the RESTCONF API.  There MUST be exactly one   "restconf" link relation returned by the device.   The client discovers this by getting the "/.well-known/host-meta"   resource ([RFC6415]) and using the <Link> element containing the   "restconf" attribute :   Example returning /restconf:   The client might send:      GET /.well-known/host-meta HTTP/1.1      Host: example.com      Accept: application/xrd+xml   The server might respond:      HTTP/1.1 200 OK      Content-Type: application/xrd+xml      Content-Length: nnn      <XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0'>          <Link rel='restconf' href='/restconf'/>      </XRD>   After discovering the RESTCONF API root, the client MUST use this   value as the initial part of the path in the request URI, in any   subsequent request for a RESTCONF resource.Bierman, et al.         Expires February 16, 2017              [Page 17]Internet-Draft                  RESTCONF                     August 2016   In this example, the client would use the path "/restconf" as the   RESTCONF root resource.   Example returning /top/restconf:   The client might send:      GET /.well-known/host-meta HTTP/1.1      Host: example.com      Accept: application/xrd+xml   The server might respond:      HTTP/1.1 200 OK      Content-Type: application/xrd+xml      Content-Length: nnn      <XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0'>          <Link rel='restconf' href='/top/restconf'/>      </XRD>   In this example, the client would use the path "/top/restconf" as the   RESTCONF root resource.   The client can now determine the operation resources supported by the   the server.  In this example a custom "play" operation is supported:   The client might send:      GET /top/restconf/operations HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond:      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:00 GMT      Server: example-server      Cache-Control: no-cache      Last-Modified: Sun, 22 Apr 2016 01:00:14 GMT      Content-Type: application/yang-data+json      { "operations" : { "example-jukebox:play" : [null] } }   If the Extensible Resource Descriptor (XRD) contains more than one   link relation, then only the relation named "restconf" is relevant to   this specification.Bierman, et al.         Expires February 16, 2017              [Page 18]Internet-Draft                  RESTCONF                     August 2016   Note that any given endpoint (host:port) can only support one   RESTCONF server, due to the root resource discovery mechanism.  This   limits the number of RESTCONF servers that can run concurrently on a   host, since each server must use a different port.3.2.  RESTCONF Media Types   The RESTCONF protocol defines two application specific media types to   identify representations of data which conforms to the schema for a   particular YANG construct.   This document defines media types for XML and JSON serialization of   YANG data.  Other documents MAY define other media types for   different serializations of YANG data.  The "application/   yang-data-xml" media-type is defined in Section 11.3.1.  The   "application/yang-data+json" media-type is defined in Section 11.3.2.3.3.  API Resource   The API resource contains the RESTCONF root resource for the RESTCONF   datastore and operation resources.  It is the top-level resource   located at {+restconf} and has the media type "application/   yang-data-xml" or "application/yang-data+json".   YANG Tree Diagram for an API Resource:     +---- {+restconf}           +---- data           | ...           +---- operations?           | ...           +--ro yang-library-version    string   The "yang-api" YANG data template is defined using the "yang-data"   extension in the "ietf-restconf" module, found in Section 8.  It   specifies the structure and syntax of the conceptual child resources   within the API resource.   The API resource can be retrieved with the GET method.   The {+restconf} root resource name used in responses representing the   root of the "ietf-restconf" module MUST identify the "ietf-restconf"   YANG module.  For example, a request to GET the root resource   "/restconf" in JSON format will return a representation of the API   resource named "ietf-restconf:restconf".   This resource has the following child resources:Bierman, et al.         Expires February 16, 2017              [Page 19]Internet-Draft                  RESTCONF                     August 2016         +----------------------+--------------------------------+         | Child Resource       | Description                    |         +----------------------+--------------------------------+         | data                 | Contains all data resources    |         | operations           | Data-model-specific operations |         | yang-library-version | ietf-yang-library module date  |         +----------------------+--------------------------------+                           RESTCONF API Resource3.3.1.  {+restconf}/data   This mandatory resource represents the combined configuration and   state data resources that can be accessed by a client.  It cannot be   created or deleted by the client.  The datastore resource type is   defined in Section 3.4.   Example:   This example request by the client would retrieve only the non-   configuration data nodes that exist within the "library" resource,   using the "content" query parameter (see Section 4.8.1).      GET /restconf/data/example-jukebox:jukebox/library\          ?content=nonconfig HTTP/1.1      Host: example.com      Accept: application/yang-data-xml   The server might respond:      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:30 GMT      Server: example-server      Cache-Control: no-cache      Content-Type: application/yang-data-xml      <library xmlns="https://example.com/ns/example-jukebox">        <artist-count>42</artist-count>        <album-count>59</album-count>        <song-count>374</song-count>      </library>3.3.2.  {+restconf}/operations   This optional resource is a container that provides access to the   data-model-specific RPC operations supported by the server.  The   server MAY omit this resource if no data-model-specific RPC   operations are advertised.Bierman, et al.         Expires February 16, 2017              [Page 20]Internet-Draft                  RESTCONF                     August 2016   Any data-model-specific RPC operations defined in the YANG modules   advertised by the server MUST be available as child nodes of this   resource.   The access point for each RPC operation is represented as an empty   leaf.  If an operation resource is retrieved, the empty leaf   representation is returned by the server.   Operation resources are defined in Section 3.6.3.3.3.  {+restconf}/yang-library-version   This mandatory leaf identifies the revision date of the   "ietf-yang-library" YANG module that is implemented by this server.   Note that the revision date for the module version found in [RFC7895]   is used.   Example:      GET /restconf/yang-library-version HTTP/1.1      Host: example.com      Accept: application/yang-data-xml   The server might respond:      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:30 GMT      Server: example-server      Cache-Control: no-cache      Content-Type: application/yang-data-xml      <yang-library-version        xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library">\        2016-06-21\      </yang-library-version>3.4.  Datastore Resource   The "{+restconf}/data" subtree represents the datastore resource,   which is a collection of configuration data and state data nodes.   The fragment field in the request URI has no defined purpose if the   target resource is a datastore resource.   This resource type is an abstraction of the system's underlying   datastore implementation.  The client uses it to edit and retrieve   data resources, as the conceptual root of all configuration and state   data that is present on the device.Bierman, et al.         Expires February 16, 2017              [Page 21]Internet-Draft                  RESTCONF                     August 2016   Configuration edit transaction management and configuration   persistence are handled by the server and not controlled by the   client.  A datastore resource can be written directly with the POST   and PATCH methods.  Each RESTCONF edit of a datastore resource is   saved to non-volatile storage by the server, if the server supports   non-volatile storage of configuration data, as described in   Section 1.4.   If the datastore resource represented by the "{+restconf}/data"   subtree is retrieved, then the datastore and its contents are   returned by the server.  The datastore is represented by a node named   "data" in the "ietf-restconf" module namespace.3.4.1.  Edit Collision Prevention   Two edit collision detection and prevention mechanisms are provided   in RESTCONF for the datastore resource: a timestamp and an entity-   tag.  Any change to configuration data resources updates the   timestamp and entity tag of the datastore resource.  In addition, the   RESTCONF server will return an error if the datastore is locked by an   external source (e.g., NETCONF server).3.4.1.1.  Timestamp   The last change time is maintained and the "Last-Modified"   ([RFC7232], Section 2.2) header field is returned in the response for   a retrieval request.  The "If-Unmodified-Since" header field   ([RFC7232], Section 3.4) can be used in edit operation requests to   cause the server to reject the request if the resource has been   modified since the specified timestamp.   The server SHOULD maintain a last-modified timestamp for the   datastore resource, defined in Section 3.4.  This timestamp is only   affected by configuration child data resources, and MUST NOT be   updated for changes to non-configuration child data resources.  Last-   modified timestamps for data resources are discussed in Section 3.5.   If the RESTCONF server is colocated with a NETCONF server, then the   last-modified timestamp MUST be for the "running" datastore.  Note   that it is possible other protocols can cause the last-modified   timestamp to be updated.  Such mechanisms are out of scope for this   document.3.4.1.2.  Entity-Tag   The server MUST maintain a unique opaque entity-tag for the datastore   resource and MUST return it in the "ETag" ([RFC7232], Section 2.3)   header in the response for a retrieval request.  The client MAY useBierman, et al.         Expires February 16, 2017              [Page 22]Internet-Draft                  RESTCONF                     August 2016   an "If-Match" header in edit operation requests to cause the server   to reject the request if the resource entity-tag does not match the   specified value.   The server MUST maintain an entity-tag for the top-level   {+restconf}/data resource.  This entity-tag is only affected by   configuration data resources, and MUST NOT be updated for changes to   non-configuration data.  Entity-tags for data resources are discussed   in Section 3.5.  Note that each representation (e.g.  XML vs. JSON)   requires a different entity-tag.   If the RESTCONF server is colocated with a NETCONF server, then this   entity-tag MUST be for the "running" datastore.  Note that it is   possible other protocols can cause the entity-tag to be updated.   Such mechanisms are out of scope for this document.3.4.1.3.  Update Procedure   Changes to configuration data resources affect the timestamp and   entity-tag for that resource, any ancestor data resources, and the   datastore resource.   For example, an edit to disable an interface might be done by setting   the leaf "/interfaces/interface/enabled" to "false".  The "enabled"   data node and its ancestors (one "interface" list instance, and the   "interfaces" container) are considered to be changed.  The datastore   is considered to be changed when any top-level configuration data   node is changed (e.g., "interfaces").3.5.  Data Resource   A data resource represents a YANG data node that is a descendant node   of a datastore resource.  Each YANG-defined data node can be uniquely   targeted by the request-line of an HTTP method.  Containers, leafs,   leaf-list entries, list entries, anydata and anyxml nodes are data   resources.   The representation maintained for each data resource is the YANG   defined subtree for that node.  HTTP methods on a data resource   affect both the targeted data node and all its descendants, if any.   A data resource can be retrieved with the GET method.  Data resources   are accessed via the "{+restconf}/data" URI.  This sub-tree is used   to retrieve and edit data resources.  The fragment field in the   request URI has no defined purpose if the target resource is a data   resource.Bierman, et al.         Expires February 16, 2017              [Page 23]Internet-Draft                  RESTCONF                     August 20163.5.1.  Timestamp   For configuration data resources, the server MAY maintain a last-   modified timestamp for the resource, and return the "Last-Modified"   header field when it is retrieved with the GET or HEAD methods.   The "Last-Modified" header field can be used by a RESTCONF client in   subsequent requests, within the "If-Modified-Since" and   "If-Unmodified-Since" header fields.   If maintained, the resource timestamp MUST be set to the current time   whenever the resource or any configuration resource within the   resource is altered.  If not maintained, then the resource timestamp   for the datastore MUST be used instead.  If the RESTCONF server is   colocated with a NETCONF server, then the last-modified timestamp for   a configuration data resource MUST represent the instance within the   "running" datastore.   This timestamp is only affected by configuration data resources, and   MUST NOT be updated for changes to non-configuration data.3.5.2.  Entity-Tag   For configuration data resources, the server SHOULD maintain a   resource entity-tag for each resource, and return the "ETag" header   field when it is retrieved as the target resource with the GET or   HEAD methods.  If maintained, the resource entity-tag MUST be updated   whenever the resource or any configuration resource within the   resource is altered.  If not maintained, then the resource entity-tag   for the datastore MUST be used instead.   The "ETag" header field can be used by a RESTCONF client in   subsequent requests, within the "If-Match" and "If-None-Match" header   fields.   This entity-tag is only affected by configuration data resources, and   MUST NOT be updated for changes to non-configuration data.  If the   RESTCONF server is colocated with a NETCONF server, then the entity-   tag for a configuration data resource MUST represent the instance   within the "running" datastore.3.5.3.  Encoding Data Resource Identifiers in the Request URI   In YANG, data nodes can be identified with an absolute XPath   expression, defined in [XPath], starting from the document root to   the target resource.  In RESTCONF, URI-encoded path expressions are   used instead.Bierman, et al.         Expires February 16, 2017              [Page 24]Internet-Draft                  RESTCONF                     August 2016   A predictable location for a data resource is important, since   applications will code to the YANG data model module, which uses   static naming and defines an absolute path location for all data   nodes.   A RESTCONF data resource identifier is encoded from left to right,   starting with the top-level data node, according to the "api-path"   rule in Section 3.5.3.1.  The node name of each ancestor of the   target resource node is encoded in order, ending with the node name   for the target resource.  If a node in the path is defined in another   module than its parent node, or its parent is the datastore, then the   module name followed by a colon character (":") MUST be prepended to   the node name in the resource identifier.  See Section 3.5.3.1 for   details.   If a data node in the path expression is a YANG leaf-list node, then   the leaf-list value MUST be encoded according to the following rules:   o  The identifier for the leaf-list MUST be encoded using one path      segment [RFC3986].   o  The path segment is constructed by having the leaf-list name,      followed by an "=" character, followed by the leaf-list value.      (e.g., /restconf/data/top-leaflist=fred).   o  The leaf-list value is specified as a string, using the canonical      representation for the YANG data type.  Any reserved characters      MUST be percent-encoded, according to [RFC3986], section 2.1 and      2.5.   o  YANG 1.1 allows duplicate leaf-list values for non-configuration      data.  In this case there is no mechanism to specify the exact      matching leaf-list instance.   o  The comma (',') character is percent-encoded, even though multiple      key values are not possible for a leaf-list.  This is more      consistent and avoids special processing rules.   If a data node in the path expression is a YANG list node, then the   key values for the list (if any) MUST be encoded according to the   following rules:   o  The key leaf values for a data resource representing a YANG list      MUST be encoded using one path segment [RFC3986].   o  If there is only one key leaf value, the path segment is      constructed by having the list name, followed by an "=" character,      followed by the single key leaf value.Bierman, et al.         Expires February 16, 2017              [Page 25]Internet-Draft                  RESTCONF                     August 2016   o  If there are multiple key leaf values, the path segment is      constructed by having the list name, followed by the value of each      leaf identified in the "key" statement, encoded in the order      specified in the YANG "key" statement.  Each key leaf value except      the last one is followed by a comma character.   o  The key value is specified as a string, using the canonical      representation for the YANG data type.  Any reserved characters      MUST be percent-encoded, according to [RFC3986], section 2.1 and      2.5.  The comma (',') character MUST be percent-encoded if it is      present in the key value.   o  All the components in the "key" statement MUST be encoded.      Partial instance identifiers are not supported.   o  Missing key values are not allowed, so two consecutive commas are      interpreted as a comma, followed by a zero-length string, followed      by a comma.  For example, "list1=foo,,baz" would be interpreted as      a list named "list1" with 3 key values, and the second key value      is a zero-length string.   o  Note that non-configuration lists are not required to define keys.      In this case, a single list instance cannot be accessed.   o  The "list-instance" ABNF rule defined in Section 3.5.3.1      represents the syntax of a list instance identifier.   Examples:      container top {          list list1 {              key "key1 key2 key3";               ...               list list2 {                   key "key4 key5";                   ...                   leaf X { type string; }               }           }           leaf-list Y {             type uint32;           }       }   For the above YANG definition, the container "top" is defined in the   "example-top" YANG module, and a target resource URI for leaf "X"   would be encoded as follows:Bierman, et al.         Expires February 16, 2017              [Page 26]Internet-Draft                  RESTCONF                     August 2016       /restconf/data/example-top:top/list1=key1,key2,key3/\          list2=key4,key5/X   For the above YANG definition, a target resource URI for leaf-list   "Y" would be encoded as follows:       /restconf/data/example-top:top/Y=instance-value   The following example shows how reserved characters are percent-   encoded within a key value.  The value of "key1" contains a comma,   single-quote, double-quote, colon, double-quote, space, and forward   slash. (,'":" /).  Note that double-quote is not a reserved   characters and does not need to be percent-encoded.  The value of   "key2" is the empty string, and the value of "key3" is the string   "foo".   Example URL:      /restconf/data/example-top:top/list1=%2C%27"%3A"%20%2F,,foo3.5.3.1.  ABNF For Data Resource Identifiers   The "api-path" Augmented Backus-Naur Form (ABNF) syntax is used to   construct RESTCONF path identifiers.  Note that this syntax is used   for all resources, and the API path starts with the RESTCONF root   resource.  Data resources are required to be identified under the   subtree "+{restconf}/data".   An identifier is not allowed to start with the case-insensitive   string "XML", according to YANG identifier rules.  The syntax for   "api-identifier" and "key-value" MUST conform to the JSON identifier   encoding rules in Section 4 of [I-D.ietf-netmod-yang-json]: The   RESTCONF root resource path is required.  Additional sub-resource   identifiers are optional.  The characters in a key value string are   constrained, and some characters need to be percent-encoded, as   described in Section 3.5.3.Bierman, et al.         Expires February 16, 2017              [Page 27]Internet-Draft                  RESTCONF                     August 2016       api-path = root ["/" (api-identifier | list-instance)]*       root = string  ;; replacement string for {+restconf}       api-identifier = [module-name ":"] identifier       module-name = identifier       list-instance = api-identifier "=" key-value ["," key-value]*       key-value = string  ;; constrained chars are percent-encoded       string = <a quoted or unquoted string>       ;; An identifier MUST NOT start with       ;; (('X'|'x') ('M'|'m') ('L'|'l'))       identifier  = (ALPHA / "_")                     *(ALPHA / DIGIT / "_" / "-" / ".")3.5.4.  Default Handling   RESTCONF requires that a server report its default handling mode (see   Section 9.1.2 for details).  If the optional "with-defaults" query   parameter is supported by the server, a client may use it to control   retrieval of default values (see Section 4.8.9 for details).   If a leaf or leaf-list is missing from the configuration and there is   a YANG-defined default for that data resource, then the server MUST   use the YANG-defined default as the configured value.   If the target of a GET method is a data node that represents a leaf   or leaf-list that has a default value, and the leaf or leaf-list has   not been instantiated yet, the server MUST return the default   value(s) that are in use by the server.  In this case, the server   MUST ignore its basic-mode, described in Section 4.8.9, and return   the default value.   If the target of a GET method is a data node that represents a   container or list that has any child resources with default values,   for the child resources that have not been given value yet, the   server MAY return the default values that are in use by the server,   in accordance with its reported default handing mode and query   parameters passed by the client.Bierman, et al.         Expires February 16, 2017              [Page 28]Internet-Draft                  RESTCONF                     August 20163.6.  Operation Resource   An operation resource represents an RPC operation defined with the   YANG "rpc" statement or a data-model-specific action defined with a   YANG "action" statement.  It is invoked using a POST method on the   operation resource.  The fragment field in the request URI has no   defined purpose if the target resource is an operation resource.   An RPC operation is invoked as:      POST {+restconf}/operations/<operation>   The <operation> field identifies the module name and rpc identifier   string for the desired operation.   For example, if "module-A" defined a "reset" rpc operation, then   invoking the operation would be requested as follows:      POST /restconf/operations/module-A:reset HTTP/1.1      Server: example.com   An action is invoked as:      POST {+restconf}/data/<data-resource-identifier>/<action>   where <data-resource-identifier> contains the path to the data node   where the action is defined, and <action> is the name of the action.   For example, if "module-A" defined a "reset-all" action in the   container "interfaces", then invoking this action would be requested   as follows:      POST /restconf/data/module-A:interfaces/reset-all HTTP/1.1      Server: example.com   If the RPC operation is invoked without errors, and if the "rpc" or   "action" statement has no "output" section, the response message MUST   NOT include a message-body, and MUST send a "204 No Content" status-   line instead.   All operation resources representing RPC operations supported by the   server MUST be identified in the {+restconf}/operations subtree   defined in Section 3.3.2.  Operation resources representing YANG   actions are not identified in this subtree since they are invoked   using a URI within the {+restconf}/data subtree.Bierman, et al.         Expires February 16, 2017              [Page 29]Internet-Draft                  RESTCONF                     August 20163.6.1.  Encoding Operation Resource Input Parameters   If the "rpc" or "action" statement has an "input" section then   instances of these input parameters are encoded in the module   namespace where the "rpc" or "action" statement is defined, in an XML   element or JSON object named "input", which is in the module   namespace where the "rpc" or "action" statement is defined.   If the "rpc" or "action" statement has an "input" section and the   "input" object tree contains any child data nodes which are   considered mandatory nodes, then a message-body MUST be sent by the   client in the request.   If the "rpc" or "action" statement has an "input" section and the   "input" object tree does not contain any child nodes which are   considered mandatory nodes, then a message-body MAY be sent by the   client in the request.   If the "rpc" or "action" statement has no "input" section, the   request message MUST NOT include a message-body.   Examples:   The following YANG module is used for the RPC operation examples in   this section.Bierman, et al.         Expires February 16, 2017              [Page 30]Internet-Draft                  RESTCONF                     August 2016   module example-ops {     namespace "https://example.com/ns/example-ops";     prefix "ops";     organization "Example, Inc.";     contact "support at example.com";     description "Example Operations Data Model Module";     revision "2016-07-07" {       description "Initial version.";       reference "example.com document 3-3373";     }     rpc reboot {       input {         leaf delay {           units seconds;           type uint32;           default 0;         }         leaf message { type string; }         leaf language { type string; }       }     }     rpc get-reboot-info {       output {         leaf reboot-time {           units seconds;           type uint32;         }         leaf message { type string; }         leaf language { type string; }       }     }   }   The following YANG module is used for the YANG action examples in   this section.Bierman, et al.         Expires February 16, 2017              [Page 31]Internet-Draft                  RESTCONF                     August 2016   module example-actions {     yang-version 1.1;     namespace "https://example.com/ns/example-actions";     prefix "act";     import ietf-yang-types { prefix yang; }     organization "Example, Inc.";     contact "support at example.com";     description "Example Actions Data Model Module";     revision "2016-07-07" {       description "Initial version.";       reference "example.com document 2-9973";     }     revision "2016-03-10";     container interfaces {       list interface {         key name;         leaf name { type string; }         action reset {           input {             leaf delay {               units seconds;               type uint32;               default 0;             }           }         }         action get-last-reset-time {           output {             leaf last-reset {               type yang:date-and-time;               mandatory true;             }           }         }       }     }   }   RPC Input Example:Bierman, et al.         Expires February 16, 2017              [Page 32]Internet-Draft                  RESTCONF                     August 2016   The client might send the following POST request message to invoke   the "reboot" RPC operation:      POST /restconf/operations/example-ops:reboot HTTP/1.1      Host: example.com      Content-Type: application/yang-data-xml      <input xmlns="https://example.com/ns/example-ops">       <delay>600</delay>       <message>Going down for system maintenance</message>       <language>en-US</language>      </input>   The server might respond:      HTTP/1.1 204 No Content      Date: Mon, 25 Apr 2016 11:01:00 GMT      Server: example-server   The same example request message is shown here using JSON encoding:      POST /restconf/operations/example-ops:reboot HTTP/1.1      Host: example.com      Content-Type: application/yang-data+json      {        "example-ops:input" : {          "delay" : 600,          "message" : "Going down for system maintenance",          "language" : "en-US"        }      }   Action Input Example:   The client might send the following POST request message to invoke   the "reset" action:      POST /restconf/data/example-actions:interfaces/\         interface=eth0/reset HTTP/1.1      Host: example.com      Content-Type: application/yang-data-xml      <input xmlns="https://example.com/ns/example-actions">        <delay>600</delay>      </input>   The server might respond:Bierman, et al.         Expires February 16, 2017              [Page 33]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 204 No Content      Date: Mon, 25 Apr 2016 11:01:00 GMT      Server: example-server   The same example request message is shown here using JSON encoding:      POST /restconf/data/example-actions:interfaces/\        interface=eth0/reset HTTP/1.1      Host: example.com      Content-Type: application/yang-data+json      { "example-actions:input" : {          "delay" : 600        }      }3.6.2.  Encoding Operation Resource Output Parameters   If the "rpc" or "action" statement has an "output" section then   instances of these output parameters are encoded in the module   namespace where the "rpc" or "action" statement is defined, in an XML   element or JSON object named "output", which is in the module   namespace where the "rpc" or "action" statement is defined.   If the RPC operation is invoked without errors, and if the "rpc" or   "action" statement has an "output" section and the "output" object   tree contains any child data nodes which are considered mandatory   nodes, then a response message-body MUST be sent by the server in the   response.   If the RPC operation is invoked without errors, and if the "rpc" or   "action" statement has an "output" section and the "output" object   tree does not contain any child nodes which are considered mandatory   nodes, then a response message-body MAY be sent by the server in the   response.   The request URI is not returned in the response.  Knowledge of the   request URI may be needed to associate the output with the specific   "rpc" or "action" statement used in the request.   Examples:   RPC Output Example:   The "example-ops" YANG module defined in Section 3.6.1 is used for   this example.Bierman, et al.         Expires February 16, 2017              [Page 34]Internet-Draft                  RESTCONF                     August 2016   The client might send the following POST request message to invoke   the "get-reboot-info" operation:      POST /restconf/operations/example-ops:get-reboot-info HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond:      HTTP/1.1 200 OK      Date: Mon, 25 Apr 2016 11:10:30 GMT      Server: example-server      Content-Type: application/yang-data+json      {        "example-ops:output" : {          "reboot-time" : 30,          "message" : "Going down for system maintenance",          "language" : "en-US"        }      }   The same response is shown here using XML encoding:      HTTP/1.1 200 OK      Date: Mon, 25 Apr 2016 11:10:30 GMT      Server: example-server      Content-Type: application/yang-data-xml      <output xmlns="https://example.com/ns/example-ops">        <reboot-time>30</reboot-time>        <message>Going down for system maintenance</message>        <language>en-US</language>      </output>   Action Output Example:   The "example-actions" YANG module defined in Section 3.6.1 is used   for this example.   The client might send the following POST request message to invoke   the "get-last-reset-time" action:      POST /restconf/data/example-actions:interfaces/\         interface=eth0/get-last-reset-time HTTP/1.1      Host: example.com      Accept: application/yang-data+jsonBierman, et al.         Expires February 16, 2017              [Page 35]Internet-Draft                  RESTCONF                     August 2016   The server might respond:      HTTP/1.1 200 OK      Date: Mon, 25 Apr 2016 11:10:30 GMT      Server: example-server      Content-Type: application/yang-data+json      {        "example-actions:output" : {          "last-reset" : "2015-10-10T02:14:11Z"        }      }3.6.3.  Encoding Operation Resource Errors   If any errors occur while attempting to invoke the operation or   action, then an "errors" media type is returned with the appropriate   error status.   If the RPC operation input is not valid, or the RPC operation is   invoked but errors occur, then a message-body MUST be sent by the   server, containing an "errors" resource, as defined in Section 3.9.   A detailed example of an operation resource error response can be   found in Section 3.6.3.   Using the "reboot" RPC operation from the example in Section 3.6.1,   the client might send the following POST request message:      POST /restconf/operations/example-ops:reboot HTTP/1.1      Host: example.com      Content-Type: application/yang-data-xml      <input xmlns="https://example.com/ns/example-ops">        <delay>-33</delay>        <message>Going down for system maintenance</message>        <language>en-US</language>      </input>   The server might respond with an "invalid-value" error:Bierman, et al.         Expires February 16, 2017              [Page 36]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 400 Bad Request      Date: Mon, 25 Apr 2016 11:10:30 GMT      Server: example-server      Content-Type: application/yang-data-xml      <errors xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf">        <error>          <error-type>protocol</error-type>          <error-tag>invalid-value</error-tag>          <error-path xmlns:ops="https://example.com/ns/example-ops">            /ops:input/ops:delay          </error-path>          <error-message>Invalid input parameter</error-message>        </error>      </errors>   The same response is shown here in JSON encoding:      HTTP/1.1 400 Bad Request      Date: Mon, 25 Apr 2016 11:10:30 GMT      Server: example-server      Content-Type: application/yang-data+json      { "ietf-restconf:errors" : {          "error" : [            {              "error-type" : "protocol",              "error-tag" : "invalid-value",              "error-path" : "/example-ops:input/delay",              "error-message" : "Invalid input parameter",            }          ]        }      }3.7.  Schema Resource   The server can optionally support retrieval of the YANG modules it   supports.  If retrieval is supported, then the "schema" leaf MUST be   present in the associated "module" list entry, defined in [RFC7895].   To retrieve a YANG module, a client first needs to get the URL for   retrieving the schema, which is stored in the "schema" leaf.  Note   that there is no required structure for this URL.  The URL value   shown below is just an example.   The client might send the following GET request message:Bierman, et al.         Expires February 16, 2017              [Page 37]Internet-Draft                  RESTCONF                     August 2016      GET /restconf/data/ietf-yang-library:modules-state/\          module=example-jukebox,2016-08-15/schema HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond:      HTTP/1.1 200 OK      Date: Thu, 11 Feb 2016 11:10:30 GMT      Server: example-server      Content-Type: application/yang-data+json      {        "ietf-yang-library:schema" :         "https://example.com/mymodules/example-jukebox/2016-08-15"      }   Next the client needs to retrieve the actual YANG schema.   The client might send the following GET request message:      GET https://example.com/mymodules/example-jukebox/\         2016-08-15 HTTP/1.1      Host: example.com      Accept: application/yang   The server might respond:      HTTP/1.1 200 OK      Date: Thu, 11 Feb 2016 11:10:31 GMT      Server: example-server      Content-Type: application/yang      module example-jukebox {         // contents of YANG module deleted for this example...      }3.8.  Event Stream Resource   An "event stream" resource represents a source for system generated   event notifications.  Each stream is created and modified by the   server only.  A client can retrieve a stream resource or initiate a   long-poll server sent event stream, using the procedure specified in   Section 6.3.Bierman, et al.         Expires February 16, 2017              [Page 38]Internet-Draft                  RESTCONF                     August 2016   An event stream functions according to the NETCONF Notifications   specification [RFC5277].  The available streams can be retrieved from   the stream list, which specifies the syntax and semantics of the   stream resources.  The fragment field in the request URI has no   defined purpose if the target resource is an event stream resource.3.9.  Errors YANG Data Template   The "errors" YANG data template models a collection of error   information that is sent as the message-body in a server response   message, if an error occurs while processing a request message.  It   is not considered as a resource type because no instances can be   retrieved with a GET request.   The "ietf-restconf" YANG module contains the "yang-errors" YANG data   template, that specifies the syntax and semantics of an "errors"   container within a RESTCONF response.  RESTCONF error handling   behavior is defined in Section 7.4.  Operations   The RESTCONF protocol uses HTTP methods to identify the CRUD   operations requested for a particular resource.   The following table shows how the RESTCONF operations relate to   NETCONF protocol operations and for the NETCONF <edit-config>   operation, the "nc:operation" attribute.       +----------+-----------------------------------------------+       | RESTCONF | NETCONF                                       |       +----------+-----------------------------------------------+       | OPTIONS  | none                                          |       | HEAD     | none                                          |       | GET      | <get-config>, <get>                           |       | POST     | <edit-config> (nc:operation="create")         |       | POST     | invoke an RPC operation                       |       | PUT      | <edit-config> (nc:operation="create/replace") |       | PATCH    | <edit-config> (nc:operation="merge")          |       | DELETE   | <edit-config> (nc:operation="delete")         |       +----------+-----------------------------------------------+                         CRUD Methods in RESTCONF   The "remove" edit operation attribute for the NETCONF <edit-config>   RPC operation is not supported by the HTTP DELETE method.  The   resource must exist or the DELETE method will fail.  The PATCH method   is equivalent to a "merge" edit operation when using a plain patchBierman, et al.         Expires February 16, 2017              [Page 39]Internet-Draft                  RESTCONF                     August 2016   (see Section 4.6.1); other media-types may provide more granular   control.   Access control mechanisms are used to limit what CRUD operations can   be used.  In particular, RESTCONF is compatible with the NETCONF   Access Control Model (NACM) [RFC6536], as there is a specific mapping   between RESTCONF and NETCONF operations.  The resource path needs to   be converted internally by the server to the corresponding YANG   instance-identifier.  Using this information, the server can apply   the NACM access control rules to RESTCONF messages.   The server MUST NOT allow any RESTCONF operation for any resources   that the client is not authorized to access.   Implementation of all methods (except PATCH [RFC5789]) are defined in   [RFC7231].  This section defines the RESTCONF protocol usage for each   HTTP method.4.1.  OPTIONS   The OPTIONS method is sent by the client to discover which methods   are supported by the server for a specific resource (e.g., GET, POST,   DELETE, etc.).  The server MUST implement this method.   If the PATCH method is supported, then the "Accept-Patch" header   field MUST be supported and returned in the response to the OPTIONS   request, as defined in [RFC5789].4.2.  HEAD   The RESTCONF server MUST support the HEAD method.  The HEAD method is   sent by the client to retrieve just the header fields (which contain   the metadata for a resource) that would be returned for the   comparable GET method, without the response message-body.  It is   supported for all resources that support the GET method.   The request MUST contain a request URI that contains at least the   root resource.  The same query parameters supported by the GET method   are supported by the HEAD method.   The access control behavior is enforced as if the method was GET   instead of HEAD.  The server MUST respond the same as if the method   was GET instead of HEAD, except that no response message-body is   included.Bierman, et al.         Expires February 16, 2017              [Page 40]Internet-Draft                  RESTCONF                     August 20164.3.  GET   The RESTCONF server MUST support the GET method.  The GET method is   sent by the client to retrieve data and metadata for a resource.  It   is supported for all resource types, except operation resources.  The   request MUST contain a request URI that contains at least the root   resource.   The server MUST NOT return any data resources for which the user does   not have read privileges.  If the user is not authorized to read the   target resource, an error response containing a "401 Unauthorized"   status-line SHOULD be returned.  The error-tag value "access-denied"   is returned in this case.  A server MAY return a "404 Not Found"   status-line, as described in section 6.5.3 in [RFC7231].  The error-   tag value "invalid-value" is returned in this case.   If the user is authorized to read some but not all of the target   resource, the unauthorized content is omitted from the response   message-body, and the authorized content is returned to the client.   If any content is returned to the client, then the server MUST send a   valid response message-body.  More than one element MUST NOT be   returned for XML encoding.  If multiple elements are sent in a JSON   message-body, then they MUST be sent as a JSON array.  In this case   any timestamp or entity-tag returned in the response MUST be   associated with the first element returned.   If a retrieval request for a data resource representing a YANG leaf-   list or list object identifies more than one instance, and XML   encoding is used in the response, then an error response containing a   "400 Bad Request" status-line MUST be returned by the server.  The   error-tag value "invalid-value" is used in this case.  Note that a   non-configuration list is not required to defined any keys.  In this   case, retrieval of a single list instance is not possible.   If a retrieval request for a data resource represents an instance   that does not exist, then an error response containing a "404 Not   Found" status-line MUST be returned by the server.  The error-tag   value "invalid-value" is used in this case.   If the target resource of a retrieval request is for an operation   resource then a "405 Method Not Allowed" status-line MUST be returned   by the server.  The error-tag value "operation-not-supported" is used   in this case.   Note that the way that access control is applied to data resources   may not be completely compatible with HTTP caching.  The Last-   Modified and ETag header fields maintained for a data resource areBierman, et al.         Expires February 16, 2017              [Page 41]Internet-Draft                  RESTCONF                     August 2016   not affected by changes to the access control rules for that data   resource.  It is possible for the representation of a data resource   that is visible to a particular client to be changed without   detection via the Last-Modified or ETag values.   Example:   The client might request the response header fields for an XML   representation of the a specific "album" resource:      GET /restconf/data/example-jukebox:jukebox/\         library/artist=Foo%20Fighters/album=Wasting%20Light HTTP/1.1      Host: example.com      Accept: application/yang-data-xml   The server might respond:      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:02:40 GMT      Server: example-server      Content-Type: application/yang-data-xml      Cache-Control: no-cache      ETag: "a74eefc993a2b"      Last-Modified: Mon, 23 Apr 2016 11:02:14 GMT      <album xmlns="http://example.com/ns/example-jukebox"             xmlns:jbox="http://example.com/ns/example-jukebox">        <name>Wasting Light</name>        <genre>jbox:alternative</genre>        <year>2011</year>      </album>4.4.  POST   The RESTCONF server MUST support the POST method.  The POST method is   sent by the client to create a data resource or invoke an operation   resource.  The server uses the target resource type to determine how   to process the request.      +-----------+------------------------------------------------+      | Type      | Description                                    |      +-----------+------------------------------------------------+      | Datastore | Create a top-level configuration data resource |      | Data      | Create a configuration data child resource     |      | Operation | Invoke an RPC operation                        |      +-----------+------------------------------------------------+                     Resource Types that Support POSTBierman, et al.         Expires February 16, 2017              [Page 42]Internet-Draft                  RESTCONF                     August 20164.4.1.  Create Resource Mode   If the target resource type is a datastore or data resource, then the   POST is treated as a request to create a top-level resource or child   resource, respectively.  The message-body is expected to contain the   content of a child resource to create within the parent (target   resource).  The message-body MUST contain exactly one instance of the   expected data resource.  The data-model for the child tree is the   subtree as defined by YANG for the child resource.   The "insert" Section 4.8.5 and "point" Section 4.8.6 query parameters   MUST be supported by the POST method for datastore and data   resources.  These parameters are only allowed if the list or leaf-   list is ordered-by user.   If the POST method succeeds, a "201 Created" status-line is returned   and there is no response message-body.  A "Location" header field   identifying the child resource that was created MUST be present in   the response in this case.   If the data resource already exists, then the POST request MUST fail   and a "409 Conflict" status-line MUST be returned.  The error-tag   value "resource-denied" is used in this case.   If the user is not authorized to create the target resource, an error   response containing a "403 Forbidden" status-line SHOULD be returned.   The error-tag value "access-denied" is used in this case.  A server   MAY return a "404 Not Found" status-line, as described in section   6.5.3 in [RFC7231].  The error-tag value "invalid-value" is used in   this case.  All other error responses are handled according to the   procedures defined in Section 7.   Example:   To create a new "jukebox" resource, the client might send:      POST /restconf/data HTTP/1.1      Host: example.com      Content-Type: application/yang-data+json      { "example-jukebox:jukebox" : {} }   If the resource is created, the server might respond as follows:Bierman, et al.         Expires February 16, 2017              [Page 43]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 201 Created      Date: Mon, 23 Apr 2016 17:01:00 GMT      Server: example-server      Location: https://example.com/restconf/data/\          example-jukebox:jukebox      Last-Modified: Mon, 23 Apr 2016 17:01:00 GMT      ETag: "b3a3e673be2"   Refer to Appendix D.2.1 for more resource creation examples.4.4.2.  Invoke Operation Mode   If the target resource type is an operation resource, then the POST   method is treated as a request to invoke that operation.  The   message-body (if any) is processed as the operation input parameters.   Refer to Section 3.6 for details on operation resources.   If the POST request succeeds, a "200 OK" status-line is returned if   there is a response message-body, and a "204 No Content" status-line   is returned if there is no response message-body.   If the user is not authorized to invoke the target operation, an   error response containing a "403 Forbidden" status-line is returned   to the client.  The error-tag value "access-denied" is used in this   case.  All other error responses are handled according to the   procedures defined in Section 7.   Example:   In this example, the client is invoking the "play" operation defined   in the "example-jukebox" YANG module.   A client might send a "play" request as follows:      POST /restconf/operations/example-jukebox:play HTTP/1.1      Host: example.com      Content-Type: application/yang-data+json      {        "example-jukebox:input" : {          "playlist" : "Foo-One",          "song-number" : 2        }      }   The server might respond:Bierman, et al.         Expires February 16, 2017              [Page 44]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 204 No Content      Date: Mon, 23 Apr 2016 17:50:00 GMT      Server: example-server4.5.  PUT   The RESTCONF server MUST support the PUT method.  The PUT method is   sent by the client to create or replace the target data resource.  A   request message-body MUST be present, representing the new data   resource, or the server MUST return "400 Bad Request" status-line.   The error-tag value "invalid-value" is used in this case.   Both the POST and PUT methods can be used to create data resources.   The difference is that for POST, the client does not provide the   resource identifier for the resource that will be created.  The   target resource for the POST method for resource creation is the   parent of the new resource.  The target resource for the PUT method   for resource creation is the new resource.   The PUT method MUST be supported for data and datastore resources.  A   PUT on the datastore resource is used to replace the entire contents   of the datastore.  A PUT on a data resource only replaces that data   resource within the datastore.   The "insert" (Section 4.8.5) and "point" (Section 4.8.6) query   parameters MUST be supported by the PUT method for data resources.   These parameters are only allowed if the list or leaf-list is   ordered-by user.   Consistent with [RFC7231], if the PUT request creates a new resource,   a "201 Created" status-line is returned.  If an existing resource is   modified, a "204 No Content" status-line is returned.   If the user is not authorized to create or replace the target   resource an error response containing a "403 Forbidden" status-line   SHOULD be returned.  The error-tag value "access-denied" is used in   this case.    A server MAY return a "404 Not Found" status-line, as   described in section 6.5.3 in ^RFC7231^.   The error-tag value "invalid-value" is used in this case.   All other error responses are handled according to   the procedures defined in ^error-reporting^.   If the target resource represents a YANG leaf-list, then the PUT   method MUST NOT change the value of the leaf-list instance.Bierman, et al.         Expires February 16, 2017              [Page 45]Internet-Draft                  RESTCONF                     August 2016   If the target resource represents a YANG list instance, then the key   leaf values in message-body representation MUST be the same as the   key leaf values in the request URI.  The PUT method MUST NOT be used   to change the key leaf values for a data resource instance.   Example:   An "album" child resource defined in the "example-jukebox" YANG   module is replaced or created if it does not already exist.   To replace the "album" resource contents, the client might send as   follows:      PUT /restconf/data/example-jukebox:jukebox/\          library/artist=Foo%20Fighters/album=Wasting%20Light HTTP/1.1      Host: example.com      Content-Type: application/yang-data+json      {        "example-jukebox:album" : [          {            "name" : "Wasting Light",            "genre" : "example-jukebox:alternative",            "year" : 2011          }        ]      }   If the resource is updated, the server might respond:      HTTP/1.1 204 No Content      Date: Mon, 23 Apr 2016 17:04:00 GMT      Server: example-server      Last-Modified: Mon, 23 Apr 2016 17:04:00 GMT      ETag: "b27480aeda4c"   The same request is shown here using XML encoding:Bierman, et al.         Expires February 16, 2017              [Page 46]Internet-Draft                  RESTCONF                     August 2016      PUT /restconf/data/example-jukebox:jukebox/\          library/artist=Foo%20Fighters/album=Wasting%20Light HTTP/1.1      Host: example.com      Content-Type: application/yang-data-xml      <album xmlns="http://example.com/ns/example-jukebox"             xmlns:jbox="http://example.com/ns/example-jukebox">        <name>Wasting Light</name>        <genre>jbox:alternative</genre>        <year>2011</year>      </album>4.6.  PATCH   The RESTCONF server MUST support the PATCH method.  RESTCONF uses the   HTTP PATCH method defined in [RFC5789] to provide an extensible   framework for resource patching mechanisms.  It is optional to   implement by the server.  Each patch mechanism needs a unique media   type.  Zero or more patch media types MAY be supported by the server.   The media types supported by a server can be discovered by the client   by sending an OPTIONS request, and examining the Accept-Patch header   field in the response.  (see Section 4.1).   This document defines one patch mechanism (Section 4.6.1).  Another   patch mechanism, the YANG PATCH mechanism, is defined in   [I-D.ietf-netconf-yang-patch].  Other patch mechanisms may be defined   by future specifications.   If the target resource instance does not exist, the server MUST NOT   create it.   If the PATCH request succeeds, a "200 OK" status-line is returned if   there is a message-body, and "204 No Content" is returned if no   response message-body is sent.   If the user is not authorized to alter the target resource an error   response containing a "403 Forbidden" status-line SHOULD be returned.   A server MAY return a "404 Not Found" status-line, as described in   section 6.5.3 in [RFC7231].  The error-tag value "invalid-value" is   used in this case.  All other error responses are handled according   to the procedures defined in Section 7.4.6.1.  Plain Patch   The plain patch mechanism merges the contents of the message-body   with the target resource.  The message-body for a plain patch MUST be   present and MUST be represented by the media type "application/   yang-data-xml" or "application/yang-data+json".Bierman, et al.         Expires February 16, 2017              [Page 47]Internet-Draft                  RESTCONF                     August 2016   Plain patch can be used to create or update, but not delete, a child   resource within the target resource.  Please see   [I-D.ietf-netconf-yang-patch] for an alternate media-type supporting   the ability to delete child resources.  The YANG Patch Media Type   allows multiple sub-operations (e.g., merge, delete) within a single   PATCH method.   If the target resource represents a YANG leaf-list, then the PATCH   method MUST NOT change the value of the leaf-list instance.   If the target resource represents a YANG list instance, then the key   leaf values in message-body representation MUST be the same as the   key leaf values in the request URI.  The PATCH method MUST NOT be   used to change the key leaf values for a data resource instance.   After the plain patch is processed by the server.  a response will be   returned to the client, as specified in Section 4.6.   Example:   To replace just the "year" field in the "album" resource (instead of   replacing the entire resource with the PUT method), the client might   send a plain patch as follows.      PATCH /restconf/data/example-jukebox:jukebox/\          library/artist=Foo%20Fighters/album=Wasting%20Light HTTP/1.1      Host: example.com      If-Match: "b8389233a4c"      Content-Type: application/yang-data-xml      <album xmlns="http://example.com/ns/example-jukebox">       <year>2011</year>      </album>   If the field is updated, the server might respond:      HTTP/1.1 204 No Content      Date: Mon, 23 Apr 2016 17:49:30 GMT      Server: example-server      Last-Modified: Mon, 23 Apr 2016 17:49:30 GMT      ETag: "b2788923da4c"4.7.  DELETE   The RESTCONF server MUST support the DELETE method.  The DELETE   method is used to delete the target resource.  If the DELETE request   succeeds, a "204 No Content" status-line is returned.Bierman, et al.         Expires February 16, 2017              [Page 48]Internet-Draft                  RESTCONF                     August 2016   If the user is not authorized to delete the target resource then an   error response containing a "403 Forbidden" status-line SHOULD be   returned.  The error-tag value "access-denied" is returned in this   case.  A server MAY return a "404 Not Found" status-line, as   described in section 6.5.3 in [RFC7231].  The error-tag value   "invalid-value" is returned in this case.  All other error responses   are handled according to the procedures defined in Section 7.   If the target resource represents a configuration leaf-list or list   data node, then it MUST represent a single YANG leaf-list or list   instance.  The server MUST NOT use the DELETE method to delete more   than one such instance.   Example:   To delete the "album" resource with the key "Wasting Light", the   client might send:      DELETE /restconf/data/example-jukebox:jukebox/\          library/artist=Foo%20Fighters/album=Wasting%20Light HTTP/1.1      Host: example.com   If the resource is deleted, the server might respond:      HTTP/1.1 204 No Content      Date: Mon, 23 Apr 2016 17:49:40 GMT      Server: example-server4.8.  Query Parameters   Each RESTCONF operation allows zero or more query parameters to be   present in the request URI.  The specific parameters that are allowed   depends on the resource type, and sometimes the specific target   resource used, in the request.   o  Query parameters can be given in any order.   o  Each parameter can appear at most once in a request URI.   o  If more than one instance of a query parameter is present, then a      "400 Bad Request" status-line MUST be returned by the server.  The      error-tag value "invalid-value" is returned in this case.   o  A default value may apply if the parameter is missing.   o  Query parameter names and values are case-sensitiveBierman, et al.         Expires February 16, 2017              [Page 49]Internet-Draft                  RESTCONF                     August 2016   o  A server MUST return an error with a '400 Bad Request' status-line      if a query parameter is unexpected.  The error-tag value      "invalid-value" is returned in this case.   +---------------+---------+-----------------------------------------+   | Name          | Methods | Description                             |   +---------------+---------+-----------------------------------------+   | content       | GET,    | Select config and/or non-config data    |   |               | HEAD    | resources                               |   | depth         | GET,    | Request limited sub-tree depth in the   |   |               | HEAD    | reply content                           |   | fields        | GET,    | Request a subset of the target resource |   |               | HEAD    | contents                                |   | filter        | GET,    | Boolean notification filter for event   |   |               | HEAD    | stream resources                        |   | insert        | POST,   | Insertion mode for ordered-by user data |   |               | PUT     | resources                               |   | point         | POST,   | Insertion point for ordered-by user     |   |               | PUT     | data resources                          |   | start-time    | GET,    | Replay buffer start time for event      |   |               | HEAD    | stream resources                        |   | stop-time     | GET,    | Replay buffer stop time for event       |   |               | HEAD    | stream resources                        |   | with-defaults | GET,    | Control retrieval of default values     |   |               | HEAD    |                                         |   +---------------+---------+-----------------------------------------+                         RESTCONF Query Parameters   Refer to Appendix D.3 for examples of query parameter usage.   If vendors define additional query parameters, they SHOULD use a   prefix (such as the enterprise or organization name) for query   parameter names in order to avoid collisions with other parameters.4.8.1.  The "content" Query Parameter   The "content" parameter controls how descendant nodes of the   requested data nodes will be processed in the reply.   The allowed values are:Bierman, et al.         Expires February 16, 2017              [Page 50]Internet-Draft                  RESTCONF                     August 2016    +-----------+-----------------------------------------------------+    | Value     | Description                                         |    +-----------+-----------------------------------------------------+    | config    | Return only configuration descendant data nodes     |    | nonconfig | Return only non-configuration descendant data nodes |    | all       | Return all descendant data nodes                    |    +-----------+-----------------------------------------------------+   This parameter is only allowed for GET methods on datastore and data   resources.  A "400 Bad Request" status-line is returned if used for   other methods or resource types.   If this query parameter is not present, the default value is "all".   This query parameter MUST be supported by the server.4.8.2.  The "depth" Query Parameter   The "depth" parameter is used to limit the depth of subtrees returned   by the server.  Data nodes with a depth value greater than the   "depth" parameter are not returned in a response for a GET method.   The requested data node has a depth level of '1'.  If the "fields"   parameter (Section 4.8.3) is used to select descendant data nodes,   then these nodes and all their ancestor nodes have a depth value of   1.  (This has the effect of including the nodes specified by the   fields, even if the "depth" value is less than the actual depth level   of the specified fields.)  Any other child node has a depth value   that is 1 greater than its parent.   The value of the "depth" parameter is either an integer between 1 and   65535, or the string "unbounded".  "unbounded" is the default.   This parameter is only allowed for GET methods on API, datastore, and   data resources.  A "400 Bad Request" status-line is returned if it   used for other methods or resource types.   By default, the server will include all sub-resources within a   retrieved resource, which have the same resource type as the   requested resource.  The exception is the datastore resource.  If   this resource type is retrieved then by default the datastore and all   child data resources are returned.   If the "depth" query parameter URI is listed in the "capability"   leaf-list in Section 9.3, then the server supports the "depth" query   parameter.Bierman, et al.         Expires February 16, 2017              [Page 51]Internet-Draft                  RESTCONF                     August 20164.8.3.  The "fields" Query Parameter   The "fields" query parameter is used to optionally identify data   nodes within the target resource to be retrieved in a GET method.   The client can use this parameter to retrieve a subset of all nodes   in a resource.   The server will return a message-body representing the target   resource, with descendant nodes pruned as specified in the   "fields-expr" value.  The server does not return a set separate sub-   resources.   A value of the "fields" query parameter matches the following rule:     fields-expr = path '(' fields-expr ')' /                   path ';' fields-expr /                   path     path = api-identifier [ '/' path ]   "api-identifier" is defined in Section 3.5.3.1.   ";" is used to select multiple nodes.  For example, to retrieve only   the "genre" and "year" of an album, use: "fields=genre;year".   Parentheses are used to specify sub-selectors of a node.  Note that   there is no path separator character '/' between a "path" field and   left parenthesis character '('.   For example, assume the target resource is the "album" list.  To   retrieve only the "label" and "catalogue-number" of the "admin"   container within an album, use:   "fields=admin(label;catalogue-number)".   "/" is used in a path to retrieve a child node of a node.  For   example, to retrieve only the "label" of an album, use:   "fields=admin/label".   This parameter is only allowed for GET methods on api, datastore, and   data resources.  A "400 Bad Request" status-line is returned if used   for other methods or resource types.   If the "fields" query parameter URI is listed in the "capability"   leaf-list in Section 9.3, then the server supports the "fields"   parameter.Bierman, et al.         Expires February 16, 2017              [Page 52]Internet-Draft                  RESTCONF                     August 20164.8.4.  The "filter" Query Parameter   The "filter" parameter is used to indicate which subset of all   possible events are of interest.  If not present, all events not   precluded by other parameters will be sent.   This parameter is only allowed for GET methods on an event stream   resource.  A "400 Bad Request" status-line is returned if used for   other methods or resource types.   The format of this parameter is an XPath 1.0 expression, and is   evaluated in the following context:   o  The set of namespace declarations is the set of prefix and      namespace pairs for all supported YANG modules, where the prefix      is the YANG module name, and the namespace is as defined by the      "namespace" statement in the YANG module.   o  The function library is the core function library defined in XPath      1.0, plus any functions defined by the data model.   o  The set of variable bindings is empty.   o  The context node is the root node.   The filter is used as defined in [RFC5277], Section 3.6.  If the   boolean result of the expression is true when applied to the   conceptual "notification" document root, then the event notification   is delivered to the client.   If the "filter" query parameter URI is listed in the "capability"   leaf-list in Section 9.3, then the server supports the "filter" query   parameter.4.8.5.  The "insert" Query Parameter   The "insert" parameter is used to specify how a resource should be   inserted within a ordered-by user list.   The allowed values are:Bierman, et al.         Expires February 16, 2017              [Page 53]Internet-Draft                  RESTCONF                     August 2016   +--------+----------------------------------------------------------+   | Value  | Description                                              |   +--------+----------------------------------------------------------+   | first  | Insert the new data as the new first entry.              |   | last   | Insert the new data as the new last entry.               |   | before | Insert the new data before the insertion point, as       |   |        | specified by the value of the "point" parameter.         |   | after  | Insert the new data after the insertion point, as        |   |        | specified by the value of the "point" parameter.         |   +--------+----------------------------------------------------------+   The default value is "last".   This parameter is only supported for the POST and PUT methods.  It is   also only supported if the target resource is a data resource, and   that data represents a YANG list or leaf-list that is ordered-by   user.   If the values "before" or "after" are used, then a "point" query   parameter for the insertion parameter MUST also be present, or a "400   Bad Request" status-line is returned.   The "insert" query parameter MUST be supported by the server.4.8.6.  The "point" Query Parameter   The "point" parameter is used to specify the insertion point for a   data resource that is being created or moved within an ordered-by   user list or leaf-list.   The value of the "point" parameter is a string that identifies the   path to the insertion point object.  The format is the same as a   target resource URI string.   This parameter is only supported for the POST and PUT methods.  It is   also only supported if the target resource is a data resource, and   that data represents a YANG list or leaf-list that is ordered-by   user.   If the "insert" query parameter is not present, or has a value other   than "before" or "after", then a "400 Bad Request" status-line is   returned.   This parameter contains the instance identifier of the resource to be   used as the insertion point for a POST or PUT method.   The "point" query parameter MUST be supported by the server.Bierman, et al.         Expires February 16, 2017              [Page 54]Internet-Draft                  RESTCONF                     August 20164.8.7.  The "start-time" Query Parameter   The "start-time" parameter is used to trigger the notification replay   feature defined in [RFC5277] and indicate that the replay should   start at the time specified.  If the stream does not support replay,   per the "replay-support" attribute returned by stream list entry for   the stream resource, then the server MUST return a "400 Bad Request"   status-line.   The value of the "start-time" parameter is of type "date-and-time",   defined in the "ietf-yang" YANG module [RFC6991].   This parameter is only allowed for GET methods on a text/event-stream   data resource.  A "400 Bad Request" status-line is returned if used   for other methods or resource types.   If this parameter is not present, then a replay subscription is not   being requested.  It is not valid to specify start times that are   later than the current time.  If the value specified is earlier than   the log can support, the replay will begin with the earliest   available notification.  A client can obtain a server's current time   by examining the "Date" header field that the server returns in   response messages, according to [RFC7231].   If this query parameter is supported by the server, then the "replay"   query parameter URI MUST be listed in the "capability" leaf-list in   Section 9.3, anf the "stop-time" query parameter MUST also be   supported by the server.   If the "replay-support" leaf has the value 'true' in the "stream"   entry (defined in Section 9.3) then the server MUST support the   "start-time" and "stop-time" query parameters for that stream.4.8.8.  The "stop-time" Query Parameter   The "stop-time" parameter is used with the replay feature to indicate   the newest notifications of interest.  This parameter MUST be used   with and have a value later than the "start-time" parameter.   The value of the "stop-time" parameter is of type "date-and-time",   defined in the "ietf-yang" YANG module [RFC6991].   This parameter is only allowed for GET methods on a text/event-stream   data resource.  A "400 Bad Request" status-line is returned if used   for other methods or resource types.Bierman, et al.         Expires February 16, 2017              [Page 55]Internet-Draft                  RESTCONF                     August 2016   If this parameter is not present, the notifications will continue   until the subscription is terminated.  Values in the future are   valid.   If this query parameter is supported by the server, then the "replay"   query parameter URI MUST be listed in the "capability" leaf-list in   Section 9.3, and the "start-time" query parameter MUST also be   supported by the server.   If the "replay-support" leaf is present in the "stream" entry   (defined in Section 9.3) then the server MUST support the   "start-time" and "stop-time" query parameters for that stream.4.8.9.  The "with-defaults" Query Parameter   The "with-defaults" parameter is used to specify how information   about default data nodes should be returned in response to GET   requests on data resources.   If the server supports this capability, then it MUST implement the   behavior in Section 4.5.1 of [RFC6243], except applied to the   RESTCONF GET operation, instead of the NETCONF operations.   +-------------------+-----------------------------------------------+   | Value             | Description                                   |   +-------------------+-----------------------------------------------+   | report-all        | All data nodes are reported                   |   | trim              | Data nodes set to the YANG default are not    |   |                   | reported                                      |   | explicit          | Data nodes set to the YANG default by the     |   |                   | client are reported                           |   | report-all-tagged | All data nodes are reported and defaults are  |   |                   | tagged                                        |   +-------------------+-----------------------------------------------+   If the "with-defaults" parameter is set to "report-all" then the   server MUST adhere to the defaults reporting behavior defined in   Section 3.1 of [RFC6243].   If the "with-defaults" parameter is set to "trim" then the server   MUST adhere to the defaults reporting behavior defined in Section 3.2   of [RFC6243].   If the "with-defaults" parameter is set to "explicit" then the server   MUST adhere to the defaults reporting behavior defined in Section 3.3   of [RFC6243].Bierman, et al.         Expires February 16, 2017              [Page 56]Internet-Draft                  RESTCONF                     August 2016   If the "with-defaults" parameter is set to "report-all-tagged" then   the server MUST adhere to the defaults reporting behavior defined in   Section 3.4 of [RFC6243].  Metadata is reported by the server as   specified in Section 5.3.  The XML encoding for the "default"   attribute sent by the server for default nodes is defined in section   6 of [RFC6243].  The JSON encoding for the "default" attribute MUST   use the same values as defined in [RFC6243], but encoded according to   the rules in [I-D.ietf-netmod-yang-metadata].  The module name   "ietf-netconf-with-defaults" MUST be used for the "default"   attribute.   If the "with-defaults" parameter is not present then the server MUST   adhere to the defaults reporting behavior defined in its "basic-mode"   parameter for the "defaults" protocol capability URI, defined in   Section 9.1.2.   If the server includes the "with-defaults" query parameter URI in the   "capability" leaf-list in Section 9.3, then the "with-defaults" query   parameter MUST be supported.   Since the server does not report the "also-supported" parameter as   described in section 4.3 of [RFC6243], it is possible that some   values for the "with-defaults" parameter will not be supported.  If   the server does not support the requested value of the   "with-defaults" parameter, the server MUST return a response with a   "400 Bad Request" status-line.  The error-tag value "invalid-value"   is used in this case.5.  Messages   The RESTCONF protocol uses HTTP entities for messages.  A single HTTP   message corresponds to a single protocol method.  Most messages can   perform a single task on a single resource, such as retrieving a   resource or editing a resource.  The exception is the PATCH method,   which allows multiple datastore edits within a single message.5.1.  Request URI Structure   Resources are represented with URIs following the structure for   generic URIs in [RFC3986].   A RESTCONF operation is derived from the HTTP method and the request   URI, using the following conceptual fields:        <OP> /<restconf>/<path>?<query>          ^       ^        ^       ^Bierman, et al.         Expires February 16, 2017              [Page 57]Internet-Draft                  RESTCONF                     August 2016          |       |        |       |        method  entry  resource  query          M       M        O        O       M=mandatory, O=optional       where:         <OP> is the HTTP method         <restconf> is the RESTCONF root resource         <path> is the Target Resource URI         <query> is the query parameter list   o  method: the HTTP method identifying the RESTCONF operation      requested by the client, to act upon the target resource specified      in the request URI.  RESTCONF operation details are described in      Section 4.   o  entry: the root of the RESTCONF API configured on this HTTP      server, discovered by getting the "/.well-known/host-meta"      resource, as described in Section 3.1.   o  resource: the path expression identifying the resource that is      being accessed by the RESTCONF operation.  If this field is not      present, then the target resource is the API itself, represented      by the YANG data template named "yang-api", found in Section 8.   o  query: the set of parameters associated with the RESTCONF message,      as defined in section 3.4 of [RFC3986].  RESTCONF parameters have      the familiar form of "name=value" pairs.  Most query parameters      are optional to implement by the server and optional to use by the      client.  Each optional query parameter is identified by a URI.      The server MUST list the optional query parameter URIs it supports      in the "capabilities" list defined in Section 9.3.   There is a specific set of parameters defined, although the server   MAY choose to support query parameters not defined in this document.   The contents of the any query parameter value MUST be encoded   according to [RFC3986], Section 3.4.  Any reserved characters MUST be   percent-encoded, according to [RFC3986], section 2.1 and 2.5.   Note that the fragment component not used by the RESTCONF protocol.   The fragment is excluded from the target URI by a server, as   described in section 5.1 of [RFC7230].   When new resources are created by the client, a "Location" header   field is returned, which identifies the path of the newly createdBierman, et al.         Expires February 16, 2017              [Page 58]Internet-Draft                  RESTCONF                     August 2016   resource.  The client uses this exact path identifier to access the   resource once it has been created.   The "target" of a RESTCONF operation is a resource.  The "path" field   in the request URI represents the target resource for the RESTCONF   operation.   Refer to Appendix D for examples of RESTCONF Request URIs.5.2.  Message Encoding   RESTCONF messages are encoded in HTTP according to [RFC7230].  The   "utf-8" character set is used for all messages.  RESTCONF message   content is sent in the HTTP message-body.   Content is encoded in either JSON or XML format.  A server MUST   support one of either XML or JSON encoding.  A server MAY support   both XML and JSON encoding.  XML encoding rules for data nodes are   defined in [I-D.ietf-netmod-rfc6020bis].  The same encoding rules are   used for all XML content.  JSON encoding rules are defined in   [I-D.ietf-netmod-yang-json].  Additional JSON encoding rules for   metadata are defined in [I-D.ietf-netmod-yang-metadata].  This   encoding is valid JSON, but also has special encoding rules to   identify module namespaces and provide consistent type processing of   YANG data.   Request input content encoding format is identified with the Content-   Type header field.  This field MUST be present if a message-body is   sent by the client.   The server MUST support the "Accept" header field and "406 Not   Acceptable" status-line, as defined in [RFC7231].  The response   output content encoding formats that the client will accept are   identified with the Accept header field in the request.  If it is not   specified, the request input encoding format SHOULD be used, or the   server MAY choose any supported content encoding format.   If there was no request input, then the default output encoding is   XML or JSON, depending on server preference.  File extensions encoded   in the request are not used to identify format encoding.   A client can determine if the RESTCONF server supports an encoding   format by sending a request using a specific format in the Content-   Type and/or Accept header field.  If the server does not support the   requested input encoding for a request, then it MUST return an error   response with a '415 Unsupported Media Type' status-line.  If the   server does not support any of the requested output encodings for aBierman, et al.         Expires February 16, 2017              [Page 59]Internet-Draft                  RESTCONF                     August 2016   request, then it MUST return an error response with a '406 Not   Acceptable' status-line.5.3.  RESTCONF Metadata   The RESTCONF protocol needs support retrieval of the same metadata   that is used in the NETCONF protocol.  Information about default   leafs, last-modified timestamps, etc. are commonly used to annotate   representations of the datastore contents.   With the XML encoding, the metadata is encoded as attributes in XML,   according to section 3.3 of [W3C.REC-xml-20081126].  With the JSON   encoding, the metadata is encoded as specified in   [I-D.ietf-netmod-yang-metadata].   The following examples are based on the example in Appendix D.3.9.   The "report-all-tagged" mode for the "with-defaults" query parameter   requires that a "default" attribute be returned for default nodes.   This example shows that attribute for the "mtu" leaf .5.3.1.  XML Metadata Encoding Example      GET /restconf/data/interfaces/interface=eth1          ?with-defaults=report-all-tagged HTTP/1.1      Host: example.com      Accept: application/yang-data-xml   The server might respond as follows.      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:00 GMT      Server: example-server      Content-Type: application/yang-data-xml      <interface        xmlns="urn:example.com:params:xml:ns:yang:example-interface">        <name>eth1</name>        <mtu xmlns:wd="urn:ietf:params:xml:ns:netconf:default:1.0"          wd:default="true">1500</mtu>        <status>up</status>      </interface>5.3.2.  JSON Metadata Encoding Example   Note that RFC 6243 defines the "default" attribute with XSD, not   YANG, so the YANG module name has to be assigned instead of derived   from the YANG module.  The value "ietf-netconf-with-defaults" is   assigned for JSON metadata encoding.Bierman, et al.         Expires February 16, 2017              [Page 60]Internet-Draft                  RESTCONF                     August 2016      GET /restconf/data/interfaces/interface=eth1\          ?with-defaults=report-all-tagged HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond as follows.      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:00 GMT      Server: example-server      Content-Type: application/yang-data+json      {        "example:interface" : [          {            "name" : "eth1",            "mtu" : 1500,            "@mtu" : {               "ietf-netconf-with-defaults:default" : true            },            "status" : "up"          }        ]      }5.4.  Return Status   Each message represents some sort of resource access.  An HTTP   "status-line" header field is returned for each request.  If a "4xx"   range status code is returned in the status-line, then the error   information SHOULD be returned in the response, according to the   format defined in Section 7.1.  If a "5xx" range status code is   returned in the status-line, then the error information MAY be   returned in the response, according to the format defined in   Section 7.1.  If a 1xx, 2xx, or 3xx range status code is returned in   the status-line, then error information MUST NOT be returned in the   response, since these ranges do not represent error conditions.5.5.  Message Caching   Since the datastore contents change at unpredictable times, responses   from a RESTCONF server generally SHOULD NOT be cached.   The server SHOULD include a "Cache-Control" header field in every   response that specifies whether the response should be cached.   Instead of relying on HTTP caching, the client SHOULD track the   "ETag" and/or "Last-Modified" header fields returned by the serverBierman, et al.         Expires February 16, 2017              [Page 61]Internet-Draft                  RESTCONF                     August 2016   for the datastore resource (or data resource if the server supports   it).  A retrieval request for a resource can include the   "If-None-Match" and/or "If-Modified-Since" header fields, which will   cause the server to return a "304 Not Modified" status-line if the   resource has not changed.  The client MAY use the HEAD method to   retrieve just the message header fields, which SHOULD include the   "ETag" and "Last-Modified" header fields, if this metadata is   maintained for the target resource.   Note that the way that access control is applied to data resources   the values in the Last-Modified and ETag headers maintained for a   data resource may not be reliable, as described in Section 4.3.6.  Notifications   The RESTCONF protocol supports YANG-defined event notifications.  The   solution preserves aspects of NETCONF Event Notifications [RFC5277]   while utilizing the Server-Sent Events [W3C.REC-eventsource-20150203]   transport strategy.6.1.  Server Support   A RESTCONF server MAY support RESTCONF notifications.  Clients may   determine if a server supports RESTCONF notifications by using the   HTTP method OPTIONS, HEAD, or GET on the stream list.  The server   does not support RESTCONF notifications if an HTTP error code is   returned (e.g., "404 Not Found" status-line).6.2.  Event Streams   A RESTCONF server that supports notifications will populate a stream   resource for each notification delivery service access point.  A   RESTCONF client can retrieve the list of supported event streams from   a RESTCONF server using the GET method on the stream list.   The "restconf-state/streams" container definition in the   "ietf-restconf-monitoring" module (defined in Section 9.3) is used to   specify the structure and syntax of the conceptual child resources   within the "streams" resource.   For example:   The client might send the following request:      GET /restconf/data/ietf-restconf-monitoring:restconf-state/\          streams HTTP/1.1      Host: example.com      Accept: application/yang-data-xmlBierman, et al.         Expires February 16, 2017              [Page 62]Internet-Draft                  RESTCONF                     August 2016   The server might send the following response:      HTTP/1.1 200 OK      Content-Type: application/yang-data-xml      <streams        xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf-monitoring">         <stream>            <name>NETCONF</name>            <description>default NETCONF event stream            </description>            <replay-support>true</replay-support>            <replay-log-creation-time>               2007-07-08T00:00:00Z            </replay-log-creation-time>            <access>               <encoding>xml</encoding>               <location>https://example.com/streams/NETCONF               </location>            </access>            <access>               <encoding>json</encoding>               <location>https://example.com/streams/NETCONF-JSON               </location>            </access>         </stream>         <stream>            <name>SNMP</name>            <description>SNMP notifications</description>            <replay-support>false</replay-support>            <access>               <encoding>xml</encoding>               <location>https://example.com/streams/SNMP</location>            </access>         </stream>         <stream>            <name>syslog-critical</name>            <description>Critical and higher severity            </description>            <replay-support>true</replay-support>            <replay-log-creation-time>               2007-07-01T00:00:00Z            </replay-log-creation-time>            <access>               <encoding>xml</encoding>               <location>                 https://example.com/streams/syslog-critical               </location>Bierman, et al.         Expires February 16, 2017              [Page 63]Internet-Draft                  RESTCONF                     August 2016            </access>         </stream>      </streams>6.3.  Subscribing to Receive Notifications   RESTCONF clients can determine the URL for the subscription resource   (to receive notifications) by sending an HTTP GET request for the   "location" leaf with the stream list entry.  The value returned by   the server can be used for the actual notification subscription.   The client will send an HTTP GET request for the URL returned by the   server with the "Accept" type "text/event-stream".   The server will treat the connection as an event stream, using the   Server Sent Events [W3C.REC-eventsource-20150203] transport strategy.   The server MAY support query parameters for a GET method on this   resource.  These parameters are specific to each event stream.   For example:   The client might send the following request:      GET /restconf/data/ietf-restconf-monitoring:restconf-state/\          streams/stream=NETCONF/access=xml/location HTTP/1.1      Host: example.com      Accept: application/yang-data-xml   The server might send the following response:      HTTP/1.1 200 OK      Content-Type: application/yang-data-xml      <location        xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf-monitoring">        https://example.com/streams/NETCONF      </location>   The RESTCONF client can then use this URL value to start monitoring   the event stream:      GET /streams/NETCONF HTTP/1.1      Host: example.com      Accept: text/event-stream      Cache-Control: no-cache      Connection: keep-aliveBierman, et al.         Expires February 16, 2017              [Page 64]Internet-Draft                  RESTCONF                     August 2016   A RESTCONF client MAY request that the server compress the events   using the HTTP header field "Accept-Encoding".  For instance:      GET /streams/NETCONF HTTP/1.1      Host: example.com      Accept: text/event-stream      Cache-Control: no-cache      Connection: keep-alive      Accept-Encoding: gzip, deflate6.3.1.  NETCONF Event Stream   The server SHOULD support the "NETCONF" event stream defined in   section 3.2.3 of [RFC5277].  For this stream, The server MAY support   the "start-time", "stop-time", and "filter" query parameters, defined   in Section 4.8.  Refer to Appendix D.3.6 for filter parameter   examples.6.4.  Receiving Event Notifications   RESTCONF notifications are encoded according to the definition of the   event stream.  The NETCONF stream defined in [RFC5277] is encoded in   XML format.   The structure of the event data is based on the "notification"   element definition in Section 4 of [RFC5277].  It MUST conform to the   schema for the "notification" element in Section 4 of [RFC5277],   except the XML namespace for the event data element is defined as:     urn:ietf:params:xml:ns:yang:ietf-restconf   For JSON encoding purposes, the module name for the "notification"   element is "ietf-restconf".   Two child nodes within the "notification" container are expected,   representing the event time and the event payload.  The "event-time"   node is defined within the "ietf-restconf" module namespace.  The   name and namespace of the payload element are determined by the YANG   module containing the notification-stmt.   In the following example, the YANG module "example-mod" is used:Bierman, et al.         Expires February 16, 2017              [Page 65]Internet-Draft                  RESTCONF                     August 2016     module example-mod {       namespace "http://example.com/event/1.0";       prefix ex;       notification event {        leaf event-class { type string; }        container reporting-entity {          leaf card { type string; }        }        leaf severity { type string; }       }     }   An example SSE event notification encoded using XML:      data: <notification      data:    xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf">      data:    <event-time>2013-12-21T00:01:00Z</event-time>      data:    <event xmlns="http://example.com/event/1.0">      data:       <event-class>fault</event-class>      data:       <reporting-entity>      data:           <card>Ethernet0</card>      data:       </reporting-entity>      data:       <severity>major</severity>      data:     </event>      data: </notification>   An example SSE event notification encoded using JSON:      data: {      data:   "ietf-restconf:notification" : {      data:     "event-time" : "2013-12-21T00:01:00Z",      data:     "example-mod:event" : {      data:       "event-class" : "fault",      data:       "reporting-entity" : { "card" : "Ethernet0" },      data:       "severity" : "major"      data:     }      data:   }      data: }   Alternatively, since neither XML nor JSON are whitespace sensitive,   the above messages can be encoded onto a single line.  For example:   For example:Bierman, et al.         Expires February 16, 2017              [Page 66]Internet-Draft                  RESTCONF                     August 2016      XML:      data: <notification xmlns="urn:ietf:params:xml:ns:yang:ietf-rest\      conf"><event-time>2013-12-21T00:01:00Z</event-time><event xmlns="\      http://example.com/event/1.0"><event-class>fault</event-class><re\      portingEntity><card>Ethernet0</card></reporting-entity><severity>\      major</severity></event></notification>      JSON:      data: {"ietf-restconf:notification":{"event-time":"2013-12-21\      T00:01:00Z","example-mod:event":{"event-class": "fault","repor\      tingEntity":{"card":"Ethernet0"},"severity":"major"}}}   The SSE specifications supports the following additional fields:   event, id and retry.  A RESTCONF server MAY send the "retry" field   and, if it does, RESTCONF clients SHOULD use it.  A RESTCONF server   SHOULD NOT send the "event" or "id" fields, as there are no   meaningful values that could be used for them that would not be   redundant to the contents of the notification itself.  RESTCONF   servers that do not send the "id" field also do not need to support   the HTTP header field "Last-Event-Id".  RESTCONF servers that do send   the "id" field SHOULD support the "start-time" query parameter as the   preferred means for a client to specify where to restart the event   stream.7.  Error Reporting   HTTP status codes are used to report success or failure for RESTCONF   operations.  The error information that NETCONF error responses   contain in the <rpc-error> element is adapted for use in RESTCONF,   and an <errors> data tree information is returned for "4xx" and "5xx"   class of status codes.   Since an operation resource is defined with a YANG "rpc" statement,   and an action is defined with a YANG "action" statement, a mapping   from the NETCONF <error-tag> value to the HTTP status code is needed.   The specific error-tag and response code to use are data-model-   specific and might be contained in the YANG "description" statement   for the "action" or "rpc" statement.Bierman, et al.         Expires February 16, 2017              [Page 67]Internet-Draft                  RESTCONF                     August 2016               +-------------------------+-----------------+               | error-tag               | status code     |               +-------------------------+-----------------+               | in-use                  | 409             |               | invalid-value           | 400, 404 or 406 |               | (request) too-big       | 413             |               | (response) too-big      | 400             |               | missing-attribute       | 400             |               | bad-attribute           | 400             |               | unknown-attribute       | 400             |               | bad-element             | 400             |               | unknown-element         | 400             |               | unknown-namespace       | 400             |               | access-denied           | 401, 403        |               | lock-denied             | 409             |               | resource-denied         | 409             |               | rollback-failed         | 500             |               | data-exists             | 409             |               | data-missing            | 409             |               | operation-not-supported | 405 or 501      |               | operation-failed        | 412 or 500      |               | partial-operation       | 500             |               | malformed-message       | 400             |               +-------------------------+-----------------+                   Mapping from error-tag to status code7.1.  Error Response Message   When an error occurs for a request message on any resource type, and   the status code that will be returned is in the "4xx" range (except   for status code "403 Forbidden"), then the server SHOULD send a   response message-body containing the information described by the   "yang-errors" YANG data template within the "ietf-restconf" module,   found in Section 8.  The Content-Type of this response message MUST   be "application/yang-data", plus optionally a structured syntax name   suffix.   The client SHOULD specify the desired encoding(s) for response   messages by specifying the appropriate media-type(s) in the Accept   header.  If the client did not specify an Accept header, then the   same structured syntax name suffix used in the request message SHOULD   be used, or the server MAY choose any supported message encoding   format.  If there is no request message the server MUST select   "application/yang-data-xml" or "application/yang-data+json",   depending on server preference.  All of the examples in this   document, except for the one below, assume that XML encoding will be   returned if there is an error.Bierman, et al.         Expires February 16, 2017              [Page 68]Internet-Draft                  RESTCONF                     August 2016   YANG Tree Diagram for <errors> data:     +---- errors           +---- error*              +---- error-type       enumeration              +---- error-tag        string              +---- error-app-tag?   string              +---- error-path?      instance-identifier              +---- error-message?   string              +---- error-info?   The semantics and syntax for RESTCONF error messages are defined with   the "yang-errors" YANG data template extension, found in Section 8.   Examples:   The following example shows an error returned for an "lock-denied"   error that can occur if a NETCONF client has locked a datastore.  The   RESTCONF client is attempting to delete a data resource.  Note that   an Accept header field is used to specify the desired encoding for   the error message.  There would be no response message-body content   if this operation was successful.      DELETE /restconf/data/example-jukebox:jukebox/\         library/artist=Foo%20Fighters/album=Wasting%20Light HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond:      HTTP/1.1 409 Conflict      Date: Mon, 23 Apr 2016 17:11:00 GMT      Server: example-server      Content-Type: application/yang-data+json      {        "ietf-restconf:errors" : {          "error" : [            {              "error-type" : "protocol",              "error-tag" : "lock-denied",              "error-message" : "Lock failed, lock already held"            }          ]        }      }Bierman, et al.         Expires February 16, 2017              [Page 69]Internet-Draft                  RESTCONF                     August 2016   The following example shows an error returned for a "data-exists"   error on a data resource.  The "jukebox" resource already exists so   it cannot be created.   The client might send:      POST /restconf/data/example-jukebox:jukebox HTTP/1.1      Host: example.com   The server might respond:      HTTP/1.1 409 Conflict      Date: Mon, 23 Apr 2016 17:11:00 GMT      Server: example-server      Content-Type: application/yang-data-xml      <errors xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf">        <error>          <error-type>protocol</error-type>          <error-tag>data-exists</error-tag>          <error-path            xmlns:rc="urn:ietf:params:xml:ns:yang:ietf-restconf"            xmlns:jbox="https://example.com/ns/example-jukebox">\            /rc:restconf/rc:data/jbox:jukebox          </error-path>          <error-message>            Data already exists, cannot create new resource          </error-message>        </error>      </errors>8.  RESTCONF Module   The "ietf-restconf" module defines conceptual definitions within an   extension and two groupings, which are not meant to be implemented as   datastore contents by a server.  E.g., the "restconf" container is   not intended to be implemented as a top-level data node (under the   "/restconf/data" URI).   Note that the "ietf-restconf" module does not have any protocol-   accessible objects, so no YANG tree diagram is shown.   RFC Ed.: update the date below with the date of RFC publication and   remove this note.   <CODE BEGINS> file "ietf-restconf@2016-08-15.yang"   module ietf-restconf {Bierman, et al.         Expires February 16, 2017              [Page 70]Internet-Draft                  RESTCONF                     August 2016     yang-version 1.1;     namespace "urn:ietf:params:xml:ns:yang: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>        Author:   Andy Bierman                  <mailto:andy@yumaworks.com>        Author:   Martin Bjorklund                  <mailto:mbj@tail-f.com>        Author:   Kent Watsen                  <mailto:kwatsen@juniper.net>";     description       "This module contains conceptual YANG specifications        for basic RESTCONF media type definitions used in        RESTCONF protocol messages.        Note that the YANG definitions within this module do not        represent configuration data of any kind.        The 'restconf-media-type' YANG extension statement        provides 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 noteBierman, et al.         Expires February 16, 2017              [Page 71]Internet-Draft                  RESTCONF                     August 2016     // Note: extracted from draft-ietf-netconf-restconf-16.txt     // RFC Ed.: update the date below with the date of RFC publication     // and remove this note.     revision 2016-08-15 {       description         "Initial revision.";       reference         "RFC XXXX: RESTCONF Protocol.";     }     extension yang-data {       argument name {         yin-element true;       }       description         "This extension is used to specify a YANG data template which          represents conceptual data defined in YANG. It is          intended to describe hierarchical data independent of          protocol context or specific message encoding format.          Data definition statements within a yang-data extension          specify the generic syntax for the specific YANG data          template, whose name is the argument of the yang-data          extension statement.          Note that this extension does not define a media-type.          A specification using this extension MUST specify the          message encoding rules, including the content media type.          The mandatory 'name' parameter value identifies the YANG          data template that is being defined. It contains the          template name.          This extension is ignored unless it appears as a top-level          statement. It MUST contain data definition statements          that result in exactly one container data node definition.          An instance of a YANG data template can thus be translated          into an XML instance document, whose top-level element          corresponds to the top-level container.          The module name and namespace value for the YANG module using          the extension statement is assigned to instance document data          conforming to the data definition statements within          this extension.          The sub-statements of this extension MUST follow the          'data-def-stmt' rule in the YANG ABNF.Bierman, et al.         Expires February 16, 2017              [Page 72]Internet-Draft                  RESTCONF                     August 2016          The XPath document root is the extension statement itself,          such that the child nodes of the document root are          represented by the data-def-stmt sub-statements within          this extension. This conceptual document is the context          for the following YANG statements:            - must-stmt            - when-stmt            - path-stmt            - min-elements-stmt            - max-elements-stmt            - mandatory-stmt            - unique-stmt            - ordered-by            - instance-identifier data type          The following data-def-stmt sub-statements are constrained          when used within a yang-data-resource extension statement.            - The list-stmt is not required to have a key-stmt defined.            - The if-feature-stmt is ignored if present.            - The config-stmt is ignored if present.            - The available identity values for any 'identityref'              leaf or leaf-list nodes is limited to the module              containing this extension statement, and the modules              imported into that module.         ";     }     rc:yang-data yang-errors {       uses errors;     }     rc:yang-data yang-api {       uses restconf;     }     grouping errors {       description         "A grouping that contains a YANG container          representing the syntax and semantics of a          YANG Patch errors report within a response message.";       container errors {         description           "Represents an error report returned by the server if            a request results in an error.";Bierman, et al.         Expires February 16, 2017              [Page 73]Internet-Draft                  RESTCONF                     August 2016         list error {           description             "An entry containing information about one              specific error that occurred while processing              a RESTCONF request.";           reference "RFC 6241, Section 4.3";           leaf error-type {             type enumeration {               enum transport {                 description "The transport layer";               }               enum rpc {                 description "The rpc or notification layer";               }               enum protocol {                 description "The protocol operation layer";               }               enum application {                 description "The server application layer";               }             }             mandatory true;             description               "The protocol layer where the error occurred.";           }           leaf error-tag {             type string;             mandatory true;             description               "The enumerated error tag.";           }           leaf error-app-tag {             type string;             description               "The application-specific error tag.";           }           leaf error-path {             type instance-identifier;             description               "The YANG instance identifier associated                with the error node.";           }           leaf error-message {Bierman, et al.         Expires February 16, 2017              [Page 74]Internet-Draft                  RESTCONF                     August 2016             type string;             description               "A message describing the error.";           }           anydata error-info {              description                "This anydata value MUST represent a container with                zero or more data nodes representing additional                error information.";           }         }       }     }     grouping restconf {       description         "Conceptual grouping representing the RESTCONF          root resource.";       container restconf {         description           "Conceptual container representing the RESTCONF            root resource.";         container data {           description             "Container representing the datastore resource.              Represents the conceptual root of all state data              and configuration data supported by the server.              The child nodes of this container can be any data              resource which are defined as top-level data nodes              from the YANG modules advertised by the server in              the ietf-yang-library module.";         }         container operations {           description             "Container for all operation resources.              Each resource is represented as an empty leaf with the              name of the RPC operation from the YANG rpc statement.              For example, the 'system-restart' RPC operation defined              in the 'ietf-system' module would be represented as              an empty leaf in the 'ietf-system' namespace. This is              a conceptual leaf, and will not actually be found in              the module:Bierman, et al.         Expires February 16, 2017              [Page 75]Internet-Draft                  RESTCONF                     August 2016                 module ietf-system {                   leaf system-reset {                     type empty;                   }                 }              To invoke the 'system-restart' RPC operation:                 POST /restconf/operations/ietf-system:system-restart              To discover the RPC operations supported by the server:                 GET /restconf/operations              In XML the YANG module namespace identifies the module:                <system-restart                   xmlns='urn:ietf:params:xml:ns:yang:ietf-system' />              In JSON the YANG module name identifies the module:                { 'ietf-system:system-restart' : [null] }             ";         }         leaf yang-library-version {           type string {             pattern '\d{4}-\d{2}-\d{2}';           }           config false;           mandatory true;           description             "Identifies the revision date of the ietf-yang-library              module that is implemented by this RESTCONF server.              Indicates the year, month, and day in YYYY-MM-DD              numeric format.";         }       }     }   }   <CODE ENDS>Bierman, et al.         Expires February 16, 2017              [Page 76]Internet-Draft                  RESTCONF                     August 20169.  RESTCONF Monitoring   The "ietf-restconf-monitoring" module provides information about the   RESTCONF protocol capabilities and event streams available from the   server.  A RESTCONF server MUST implement the   "ietf-restconf-monitoring" module.   YANG tree diagram for "ietf-restconf-monitoring" module:      +--ro restconf-state         +--ro capabilities         |  +--ro capability*   inet:uri         +--ro streams            +--ro stream* [name]               +--ro name                        string               +--ro description?                string               +--ro replay-support?             boolean               +--ro replay-log-creation-time?   yang:date-and-time               +--ro access* [encoding]                  +--ro encoding  string                  +--ro location  inet:uri9.1.  restconf-state/capabilities   This mandatory container holds the RESTCONF protocol capability URIs   supported by the server.   The server MAY maintain a last-modified timestamp for this container,   and return the "Last-Modified" header field when this data node is   retrieved with the GET or HEAD methods.  Note that the last-modified   timestamp for the datastore resource is not affected by changes to   this subtree.   The server SHOULD maintain an entity-tag for this container, and   return the "ETag" header field when this data node is retrieved with   the GET or HEAD methods.  Note that the entity-tag for the datastore   resource is not affected by changes to this subtree.   The server MUST include a "capability" URI leaf-list entry for the   "defaults" mode used by the server, defined in Section 9.1.2.   The server MUST include a "capability" URI leaf-list entry   identifying each supported optional protocol feature.  This includes   optional query parameters and MAY include other capability URIs   defined outside this document.Bierman, et al.         Expires February 16, 2017              [Page 77]Internet-Draft                  RESTCONF                     August 20169.1.1.  Query Parameter URIs   A new set of RESTCONF Capability URIs are defined to identify the   specific query parameters (defined in Section 4.8) supported by the   server.   The server MUST include a "capability" leaf-list entry for each   optional query parameter that it supports.   +------------+--------+---------------------------------------------+   | Name       | Sectio | URI                                         |   |            | n      |                                             |   +------------+--------+---------------------------------------------+   | depth      | 4.8.2  | urn:ietf:params:restconf:capability:depth:1 |   |            |        | .0                                          |   | fields     | 4.8.3  | urn:ietf:params:restconf:capability:fields: |   |            |        | 1.0                                         |   | filter     | 4.8.4  | urn:ietf:params:restconf:capability:filter: |   |            |        | 1.0                                         |   | replay     | 4.8.7  | urn:ietf:params:restconf:capability:replay: |   |            | 4.8.8  | 1.0                                         |   | with-      | 4.8.9  | urn:ietf:params:restconf:capability:with-   |   | defaults   |        | defaults:1.0                                |   +------------+--------+---------------------------------------------+                       RESTCONF Query Parameter URIs9.1.2.  The "defaults" Protocol Capability URI   This URI identifies the "basic-mode" defaults handling mode that is   used by the server for processing default leafs in requests for data   resources.  This protocol capability URI MUST be supported by the   server, and MUST be listed in the "capability" leaf-list in   Section 9.3.      +----------+--------------------------------------------------+      | Name     | URI                                              |      +----------+--------------------------------------------------+      | defaults | urn:ietf:params:restconf:capability:defaults:1.0 |      +----------+--------------------------------------------------+                     RESTCONF defaults capability URI   The URI MUST contain a query parameter named "basic-mode" with one of   the values listed below:Bierman, et al.         Expires February 16, 2017              [Page 78]Internet-Draft                  RESTCONF                     August 2016   +------------+------------------------------------------------------+   | Value      | Description                                          |   +------------+------------------------------------------------------+   | report-all | No data nodes are considered default                 |   | trim       | Values set to the YANG default-stmt value are        |   |            | default                                              |   | explicit   | Values set by the client are never considered        |   |            | default                                              |   +------------+------------------------------------------------------+   The "basic-mode" definitions are specified in the "With-Defaults   Capability for NETCONF" [RFC6243].   If the "basic-mode" is set to "report-all" then the server MUST   adhere to the defaults handling behavior defined in Section 2.1 of   [RFC6243].   If the "basic-mode" is set to "trim" then the server MUST adhere to   the defaults handling behavior defined in Section 2.2 of [RFC6243].   If the "basic-mode" is set to "explicit" then the server MUST adhere   to the defaults handling behavior defined in Section 2.3 of   [RFC6243].   Example: (split for display purposes only)      urn:ietf:params:restconf:capability:defaults:1.0?           basic-mode=explicit9.2.  restconf-state/streams   This optional container provides access to the event streams   supported by the server.  The server MAY omit this container if no   event streams are supported.   The server will populate this container with a stream list entry for   each stream type it supports.  Each stream contains a leaf called   "events" which contains a URI that represents an event stream   resource.   Stream resources are defined in Section 3.8.  Notifications are   defined in Section 6.9.3.  RESTCONF Monitoring Module   The "ietf-restconf-monitoring" module defines monitoring information   for the RESTCONF protocol.Bierman, et al.         Expires February 16, 2017              [Page 79]Internet-Draft                  RESTCONF                     August 2016   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-restconf-monitoring@2016-08-15.yang"   module ietf-restconf-monitoring {     namespace "urn:ietf:params:xml:ns:yang:ietf-restconf-monitoring";     prefix "rcmon";     import ietf-yang-types { prefix yang; }     import ietf-inet-types { prefix inet; }     organization       "IETF NETCONF (Network Configuration) Working Group";     contact       "WG Web:   <http://tools.ietf.org/wg/netconf/>        WG List:  <mailto:netconf@ietf.org>        Author:   Andy Bierman                  <mailto:andy@yumaworks.com>        Author:   Martin Bjorklund                  <mailto:mbj@tail-f.com>        Author:   Kent Watsen                  <mailto:kwatsen@juniper.net>";     description       "This module contains monitoring information for the        RESTCONF protocol.        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.";Bierman, et al.         Expires February 16, 2017              [Page 80]Internet-Draft                  RESTCONF                     August 2016     // RFC Ed.: replace XXXX with actual RFC number and remove this     // note.     // RFC Ed.: remove this note     // Note: extracted from draft-ietf-netconf-restconf-16.txt     // RFC Ed.: update the date below with the date of RFC publication     // and remove this note.     revision 2016-08-15 {       description         "Initial revision.";       reference         "RFC XXXX: RESTCONF Protocol.";     }     container restconf-state {       config false;       description         "Contains RESTCONF protocol monitoring information.";       container capabilities {         description           "Contains a list of protocol capability URIs";         leaf-list capability {           type inet:uri;           description "A RESTCONF protocol capability URI.";         }       }       container streams {         description           "Container representing the notification event streams            supported by the server.";          reference            "RFC 5277, Section 3.4, <streams> element.";         list stream {           key name;           description             "Each entry describes an event stream supported by              the server.";           leaf name {             type string;             description "The stream name";             reference "RFC 5277, Section 3.4, <name> element.";           }Bierman, et al.         Expires February 16, 2017              [Page 81]Internet-Draft                  RESTCONF                     August 2016           leaf description {             type string;             description "Description of stream content";             reference               "RFC 5277, Section 3.4, <description> element.";           }           leaf replay-support {             type boolean;             default false;             description               "Indicates if replay buffer supported for this stream.                If 'true', then the server MUST support the 'start-time'                and 'stop-time' query parameters for this stream.";             reference               "RFC 5277, Section 3.4, <replaySupport> element.";           }           leaf replay-log-creation-time {             when "../replay-support" {               description                 "Only present if notification replay is supported";             }             type yang:date-and-time;             description               "Indicates the time the replay log for this stream                was created.";             reference               "RFC 5277, Section 3.4, <replayLogCreationTime>                element.";           }           list access {             key encoding;             min-elements 1;             description               "The server will create an entry in this list for each                encoding format that is supported for this stream.                The media type 'text/event-stream' is expected                for all event streams. This list identifies the                sub-types supported for this stream.";             leaf encoding {               type string;               description                 "This is the secondary encoding format within the                  'text/event-stream' encoding used by all streams.                  The type 'xml' is supported for XML encoding.Bierman, et al.         Expires February 16, 2017              [Page 82]Internet-Draft                  RESTCONF                     August 2016                  The type 'json' is supported for JSON encoding.";             }             leaf location {               type inet:uri;               mandatory true;               description                 "Contains a URL that represents the entry point                  for establishing notification delivery via server                  sent events.";             }           }         }       }     }   }   <CODE ENDS>10.  YANG Module Library   The "ietf-yang-library" module defined in [RFC7895] provides   information about the YANG modules and submodules used by the   RESTCONF server.  Implementation is mandatory for RESTCONF servers.   All YANG modules and submodules used by the server MUST be identified   in the YANG module library.10.1.  modules-state/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.   The contents of this list are defined in the "module" YANG list   statement in [RFC7895].   Note that there are no protocol accessible objects in the   "ietf-restconf" module to implement, but it is possible that a server   will list the "ietf-restconf" module in the YANG library if it is   imported (directly or indirectly) by an implemented module.11.  IANA ConsiderationsBierman, et al.         Expires February 16, 2017              [Page 83]Internet-Draft                  RESTCONF                     August 201611.1.  The "restconf" Relation Type   This specification registers the "restconf" relation type in the Link   Relation Type Registry defined by [RFC5988]:      Relation Name:  restconf      Description:  Identifies the root of RESTCONF API as configured                    on this HTTP server.  The "restconf" relation                    defines the root of the API defined in RFCXXXX.                    Subsequent revisions of RESTCONF will use alternate                    relation values to support protocol versioning.      Reference:  RFCXXXX   `11.2.  YANG Module Registry   This document registers two URIs as namespaces in the IETF XML   registry [RFC3688].  Following the format in RFC 3688, the following   registration is requested:        URI: urn:ietf:params:xml:ns:yang:ietf-restconf        Registrant Contact: The NETMOD WG of the IETF.        XML: N/A, the requested URI is an XML namespace.        URI: urn:ietf:params:xml:ns:yang:ietf-restconf-monitoring        Registrant Contact: The NETMOD WG of the IETF.        XML: N/A, the requested URI is an XML namespace.   This document registers two YANG modules in the YANG Module Names   registry [RFC6020]:     name:         ietf-restconf     namespace:    urn:ietf:params:xml:ns:yang:ietf-restconf     prefix:       rc     // RFC Ed.: replace XXXX with RFC number and remove this note     reference:    RFCXXXX     name:         ietf-restconf-monitoring     namespace:    urn:ietf:params:xml:ns:yang:ietf-restconf-monitoring     prefix:       rcmon     // RFC Ed.: replace XXXX with RFC number and remove this note     reference:    RFCXXXXBierman, et al.         Expires February 16, 2017              [Page 84]Internet-Draft                  RESTCONF                     August 201611.3.  Media Types11.3.1.  Media Type application/yang-data-xml      Type name: application      Subtype name: yang-data      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.      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].     // 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 YANG defined data structures.Bierman, et al.         Expires February 16, 2017              [Page 85]Internet-Draft                  RESTCONF                     August 2016      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): no11.3.2.  Media Type application/yang-data+json      Type name: application      Subtype name: yang-data+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.Bierman, et al.         Expires February 16, 2017              [Page 86]Internet-Draft                  RESTCONF                     August 2016      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]     // 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 YANG defined data structures.      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: SeeBierman, et al.         Expires February 16, 2017              [Page 87]Internet-Draft                  RESTCONF                     August 2016         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): no11.4.  RESTCONF Capability URNs      [Note to RFC Editor:       The RESTCONF Protocol Capability Registry does not yet exist;       Need to ask IANA to create it; remove this note for publication      ]   This document defines a registry for RESTCONF capability identifiers.   The name of the registry is "RESTCONF Capability URNs".  The review   policy for this registry is "IETF Review".  The registry shall record   for each entry:   o  the name of the RESTCONF capability.  By convention, this name      begins with the colon ':' character.   o  the URN for the RESTCONF capability.   This document registers several capability identifiers in "RESTCONF   Capability URNs" registry:Bierman, et al.         Expires February 16, 2017              [Page 88]Internet-Draft                  RESTCONF                     August 2016     Index        Capability Identifier     ------------------------     :defaults         urn:ietf:params:restconf:capability:defaults:1.0     :depth         urn:ietf:params:restconf:capability:depth:1.0     :fields         urn:ietf:params:restconf:capability:fields:1.0     :filter         urn:ietf:params:restconf:capability:filter:1.0     :replay         urn:ietf:params:restconf:capability:replay:1.0     :with-defaults         urn:ietf:params:restconf:capability:with-defaults:1.012.  Security Considerations   The "ietf-restconf-monitoring" YANG module defined in this memo is   designed to be accessed via the NETCONF protocol [RFC6241].  The   lowest NETCONF layer is the secure transport layer, and the   mandatory-to-implement secure transport is Secure Shell (SSH)   [RFC6242].  The NETCONF access control model [RFC6536] provides the   means to restrict access for particular NETCONF users to a pre-   configured subset of all available NETCONF protocol operations and   content.   The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement   secure transport is TLS [RFC5246].  The RESTCONF protocol uses the   NETCONF access control model [RFC6536], which provides the means to   restrict access for particular RESTCONF users to a preconfigured   subset of all available RESTCONF protocol operations and content.   This section provides security considerations for the resources   defined by the RESTCONF protocol.  Security considerations for HTTPS   are defined in [RFC7230].  RESTCONF does not specify which YANG   modules a server needs to support, except the   "ietf-restconf-monitoring" module.  Security considerations for the   other modules manipulated by RESTCONF can be found in the documents   defining those YANG modules.Bierman, et al.         Expires February 16, 2017              [Page 89]Internet-Draft                  RESTCONF                     August 2016   This document does not require use of a specific client   authentication mechanism or authorization model, but it does require   that a client authentication mechanism and authorization model is   used whenever a client accesses a protected resource.  Client   authentication MUST be implemented using client certificates or MUST   be implemented using an HTTP authentication scheme.  Client   authorization MAY be configured using the NETCONF Access Control   Model (NACM) [RFC6536].   Configuration information is by its very nature sensitive.  Its   transmission in the clear and without integrity checking leaves   devices open to classic eavesdropping and false data injection   attacks.  Configuration information often contains passwords, user   names, service descriptions, and topological information, all of   which are sensitive.  There are many patterns of attack that have   been observed through operational practice with existing management   interfaces.  It would be wise for implementers to research them, and   take them into account when implementing this protocol.   Different environments may well allow different rights prior to and   then after authentication.  When a RESTCONF operation is not properly   authorized, the RESTCONF server MUST return a "401 Unauthorized"   status-line.  Note that authorization information can be exchanged in   the form of configuration information, which is all the more reason   to ensure the security of the connection.  Note that it is possible   for a client to detect configuration changes in data resources it is   not authorized to access by monitoring changes in the ETag and Last-   Modified header fields returned by the server for the datastore   resource.   A RESTCONF server implementation SHOULD attempt to prevent system   disruption due to excessive resource consumption required to fulfill   edit requests via the POST, PUT, and PATCH methods.  It may be   possible to construct an attack on such a RESTCONF server, which   attempts to consume all available memory or other resource types.13.  Acknowledgements   The authors would like to thank the following people for their   contributions to this document: Ladislav Lhotka, Juergen   Schoenwaelder, Rex Fernando, Robert Wilton, and Jonathan Hansford.   The authors would like to thank the following people for their   excellent technical reviews of this document: Mehmet Ersue, Mahesh   Jethanandani, Qin Wu, Joe Clarke, Bert Wijnen, Ladislav Lhotka,   Rodney Cummings, Frank Xialiang, Tom Petch, Robert Sparks, Balint   Uveges, Randy Presuhn, Sue Hares, Mark Nottingham, Benoit Claise,   Dale Worley, and Lionel Morand.Bierman, et al.         Expires February 16, 2017              [Page 90]Internet-Draft                  RESTCONF                     August 2016   Contributions to this material by Andy Bierman are based upon work   supported by the United States Army, 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).14.  References14.1.  Normative References   [I-D.ietf-netmod-rfc6020bis]              Bjorklund, M., "The YANG 1.1 Data Modeling Language",              draft-ietf-netmod-rfc6020bis-14 (work in progress), June              2016.   [I-D.ietf-netmod-yang-json]              Lhotka, L., "JSON Encoding of Data Modeled with YANG",              draft-ietf-netmod-yang-json-10 (work in progress), March              2016.   [I-D.ietf-netmod-yang-metadata]              Lhotka, L., "Defining and Using Metadata with YANG",              draft-ietf-netmod-yang-metadata-07 (work in progress),              March 2016.   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail              Extensions (MIME) Part Two: Media Types", RFC 2046,              November 1996.   [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.   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform              Resource Identifier (URI): Generic Syntax", STD 66,              RFC 3986, January 2005.   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security              (TLS) Protocol Version 1.2", RFC 5246, August 2008.   [RFC5277]  Chisholm, S. and H. Trevino, "NETCONF Event              Notifications", RFC 5277, July 2008.Bierman, et al.         Expires February 16, 2017              [Page 91]Internet-Draft                  RESTCONF                     August 2016   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,              Housley, R., and T. Polk, "Internet X.509 Public Key              Infrastructure Certificate and Certificate Revocation List              (CRL) Profile", RFC 5280, May 2008.   [RFC5789]  Dusseault, L. and J. Snell, "PATCH Method for HTTP",              RFC 5789, March 2010.   [RFC5988]  Nottingham, M., "Web Linking", RFC 5988, October 2010.   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the              Network Configuration Protocol (NETCONF)", RFC 6020,              October 2010.   [RFC6125]  Saint-Andre, P. and J. Hodges, "Representation and              Verification of Domain-Based Application Service Identity              within Internet Public Key Infrastructure Using X.509              (PKIX) Certificates in the Context of Transport Layer              Security (TLS)", RFC 6125, March 2011.   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,              and A. Bierman, Ed., "Network Configuration Protocol              (NETCONF)", RFC 6241, June 2011.   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,              <http://www.rfc-editor.org/info/rfc6242>.   [RFC6243]  Bierman, A. and B. Lengyel, "With-defaults Capability for              NETCONF", RFC 6243, June 2011.   [RFC6415]  Hammer-Lahav, E. and B. Cook, "Web Host Metadata",              RFC 6415, October 2011.   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration              Protocol (NETCONF) Access Control Model", RFC 6536, March              2012.   [RFC6570]  Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,              and D. Orchard, "URI Template", RFC 6570, March 2012.   [RFC6991]  Schoenwaelder, J., "Common YANG Data Types", RFC 6991,              July 2013.   [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data              Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March              2014, <http://www.rfc-editor.org/info/rfc7159>.Bierman, et al.         Expires February 16, 2017              [Page 92]Internet-Draft                  RESTCONF                     August 2016   [RFC7230]  Fielding, R. and J. Reschke, "Hypertext Transfer Protocol              (HTTP/1.1): Message Syntax and Routing", RFC 7230, June              2014.   [RFC7231]  Fielding, R. and J. Reschke, "Hypertext Transfer Protocol              (HTTP/1.1): Semantics and Content", RFC 7231, June 2014.   [RFC7232]  Fielding, R. and J. Reschke, "Hypertext Transfer Protocol              (HTTP/1.1): Conditional Requests", RFC 7232, June 2014.   [RFC7235]  Fielding, R. and J. Reschke, "Hypertext Transfer Protocol              (HTTP/1.1): Authentication", RFC 7235, June 2014.   [RFC7320]  Nottingham, M., "URI Design and Ownership", BCP 190,              RFC 7320, July 2014.   [RFC7540]  Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext              Transfer Protocol Version 2 (HTTP/2)", RFC 7540,              DOI 10.17487/RFC7540, May 2015,              <http://www.rfc-editor.org/info/rfc7540>.   [RFC7589]  Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the              NETCONF Protocol over Transport Layer Security (TLS) with              Mutual X.509 Authentication", RFC 7589,              DOI 10.17487/RFC7589, June 2015,              <http://www.rfc-editor.org/info/rfc7589>.   [RFC7895]  Bierman, A., Bjorklund, M., and K. Watsen, "YANG Module              Library", RFC 7895, June 2016.   [W3C.REC-eventsource-20150203]              Hickson, I., "Server-Sent Events", World Wide Web              Consortium Recommendation REC-eventsource-20150203,              February 2015,              <http://www.w3.org/TR/2015/REC-eventsource-20150203>.   [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,              <http://www.w3.org/TR/2008/REC-xml-20081126>.   [XPath]    Clark, J. and S. DeRose, "XML Path Language (XPath)              Version 1.0", World Wide Web Consortium Recommendation              REC-xpath-19991116, November 1999,              <http://www.w3.org/TR/1999/REC-xpath-19991116>.Bierman, et al.         Expires February 16, 2017              [Page 93]Internet-Draft                  RESTCONF                     August 201614.2.  Informative References   [I-D.ietf-netconf-yang-patch]              Bierman, A., Bjorklund, M., and K. Watsen, "YANG Patch              Media Type", draft-ietf-netconf-yang-patch-08 (work in              progress), March 2016.   [rest-dissertation]              Fielding, R., "Architectural Styles and the Design of              Network-based Software Architectures", 2000.Appendix A.  Change Log       -- RFC Ed.: remove this section before publication.   The RESTCONF issue tracker can be found here: https://github.com/   netconf-wg/restconf/issuesA.1.  v15 to v16   o  changed media type application/yang-data to application/yang-data-      xml   o  changed header to header field   o  added linewrap convention in terminology and applied in many      examples   o  clarified DELETE for leaf-list and list   o  clarified URI format for lists without keys or duplicate leaf-      lists   o  added 'yang-data extension' term and clarified 'YANG data      template' term   o  clarified that the fragment component is not part of the request      URI, per HTTP   o  clarified request URI "api-path" syntax   o  clarified many examplesA.2.  v14 to v15   o  added text for HTTP/2 usage   o  changed media type definitions per review commentsBierman, et al.         Expires February 16, 2017              [Page 94]Internet-Draft                  RESTCONF                     August 2016   o  added some clarifications and typos   o  added error-tag mapping for 406 and 412 errors   o  added clarifications based on ops-dir review by Lionel Morand   o  clarified PUT and POST differences for creating a data resource   o  clarify PUT for a datastore resource   o  added clarifications from Gen-Art review by Robert Sparks   o  clarified terminology in many placesA.3.  v13 - v14   This release addresses github issues #61, #62, #63, #65, #66, and   #67.   o  change term 'server' to 'NETCONF server'   o  add term 'RESTCONF server' also called 'server'   o  change term 'client' to 'NETCONF client'   o  add term 'RESTCONF client' also called 'client'   o  remove unused YANG terms   o  clarified operation resource and schema resource terms   o  clarified abstract and intro: RESTCONF uses NETCONF datastore      concepts   o  removed term 'protocol operation'; use 'RPC operation' instead   o  clarified edit operation from NETCONF as nc:operation   o  clarified retrieval of an operation resource   o  remove ETag and Last-Modified requirements for /modules-state and      /modules-state/module objects, since these are not configuration      data nodes   o  clarified Last-Modified and ETag requirements for datastore and      data resourcesBierman, et al.         Expires February 16, 2017              [Page 95]Internet-Draft                  RESTCONF                     August 2016   o  clarified defaults retrieval for leaf and leaf-list target      resources   o  clarified request message-body for operation resources   o  clarified query parameters for GET also allowed for HEAD   o  clarified error handling for query parameters   o  clarified XPath function library for "filter" parameter   o  added example for 'edit a data resource'   o  added term 'notification replay' from RFC 5277   o  clarified unsupported encoding format error handling   o  change term 'meta-data' to 'metadata'   o  clarified RESTCONF metadata definition   o  clarified error info not returned for 1xx, 2xx, and 3xx ranges   o  clarified operations description in ietf-restconf module   o  clarified Acknowledgements section   o  clarified some examples   o  update some references   o  update RFC 2119 boilerplate   o  remove requirements that simply restate HTTP requirements   o  remove Pragma: no-cache from examples since RFC 7234 says this      pragma is not defined for responses   o  remove suggestion MAY send Pragma: no-cache in response   o  remove table of HTTP status codes used in RESTCONF   o  changed media type names so they conform to RFC 6838   o  clarified too-big error-tag conversion   o  update SSE referenceBierman, et al.         Expires February 16, 2017              [Page 96]Internet-Draft                  RESTCONF                     August 2016   o  clarify leaf-list identifier encoding   o  removed all media types except yang-data   o  changed restconf-media-type extension to be more generic yang-data      extensionA.4.  v12 - v13   o  fix YANG library module examples (now called module-state)   o  fix terminology idnit issue   o  removed RFC 2818 reference (changed citation to RFC 7230)A.5.  v11 - v12   o  clarify query parameter requirements   o  move filter query section to match table order in sec. 4.8   o  clarify that depth default is entire subtree for datastore      resource   o  change ietf-restconf to YANG 1.1 to use anydata instead of anyxml   o  made implementation of timestamps optional since ETags are      mandatory   o  removed confusing text about data resource definition revision      date   o  clarify that errors should be returned for any resource type   o  clarified media subtype (not type) for error response   o  clarified client SHOULD (not MAY) specify errors format in Accept      header   o  clarified terminology in many sectionsA.6.  v10 - v11   o  change term 'operational data' to 'state data'   o  clarify :startup behavior   o  clarify X.509 security textBierman, et al.         Expires February 16, 2017              [Page 97]Internet-Draft                  RESTCONF                     August 2016   o  change '403 Forbidden' to '401 Unauthorized' for GET error   o  clarify MUST have one "restconf" link relation   o  clarify that NV-storage is not mandatory   o  clarify how "Last-Modified" and "ETag" header info can be used by      a client   o  clarify meaning of mandatory parameter   o  fix module name in action examples   o  clarify operation resource request needs to be known to parse the      output   o  clarify ordered-by user terminology   o  fixed JSON example in D.1.1A.7.  v09 - v10   o  address review comments: github issue #36   o  removed intro text about no knowledge of NETCONF needed   o  clarified candidate and confirmed-commit behavior in sec. 1.3   o  clarified that a RESTCONF server MUST support TLS   o  clarified choice of 403 or 404 error   o  fixed forward references to URI template (w/reference at first      use)   o  added reference to HTML5   o  made error terminology more consistent   o  clarified that only 1 list or leaf-list instance can be returned      in an XML response message-body   o  clarified that more than 1 instance must not be created by a POST      method   o  clarified that PUT cannot be used to change a leaf-list value or      any list key valuesBierman, et al.         Expires February 16, 2017              [Page 98]Internet-Draft                  RESTCONF                     August 2016   o  clarified that PATCH cannot be used to change a leaf-list value or      any list key values   o  clarified that DELETE should not be used to delete more than one      instance of a leaf-list or list   o  update JSON RFC reference   o  specified that leaf-list instances are data resources   o  specified how a leaf-list instance identifier is constructed   o  fixed get-schema example   o  clarified that if no Accept header the server SHOULD return the      type specified in RESTCONF, but MAY return any media-type,      according to HTTP rules   o  clarified that server SHOULD maintain timestamp and etag for data      resources   o  clarified default for content query parameter   o  moved terminology section earlier in doc to avoid forward usage   o  clarified intro text wrt/ interactions with NETCONF and access to      specific datastores   o  clarified server implementation requirements for YANG defaults   o  clarified that Errors is not a resource, just a media type   o  clarified that HTTP without TLS MUST NOT be used   o  add RESTCONF Extensibility section to make it clear how RESTCONF      will be extended in the future   o  add text warning that NACM does not work with HTTP caching   o  remove sec. 5.2 Message Headers   o  remove 202 Accepted from list of used status-lines -- not allowed   o  made implementation of OPTIONS MUST instead of SHOULD   o  clarified that successful PUT for altering data returns 204   o  fixed "point" parameter exampleBierman, et al.         Expires February 16, 2017              [Page 99]Internet-Draft                  RESTCONF                     August 2016   o  added example of alternate value for root resource discovery   o  added YANG action examples   o  fixed some JSON examples   o  changed default value for content query parameter to "all"   o  changed empty container JSON encoding from "[null]" to "{}"   o  added mandatory /restconf/yang-library-version leaf to advertise      revision-date of the YANG library implemented by the server   o  clarified URI encoding rules for leaf-list   o  clarified sec. 2.2 wrt/ certificates and TLS   o  added update procedure for entity tag and timestampA.8.  v08 - v09   o  fix introduction text regarding implementation requirements for      the ietf-yang-library   o  clarified HTTP authentication requirements   o  fix host-meta example   o  changed list key encoding to clarify that quoted strings are not      allowed.  Percent-encoded values are used if quotes would be      required.  A missing key is treated as a zero-length string   o  Fixed example of percent-encoded string to match YANG model   o  Changed streams examples to align with naming already usedA.9.  v07 - v08   o  add support for YANG 1.1 action statement   o  changed mandatory encoding from XML to XML or JSON   o  fix syntax in fields parameter definition   o  add meta-data encoding examples for XML and JSON   o  remove RFC 2396 references and update with 3986Bierman, et al.         Expires February 16, 2017             [Page 100]Internet-Draft                  RESTCONF                     August 2016   o  change encoding of a key so quoted string are not used, since they      are already percent-encoded.  A zero-length string is not encoded      (/list=foo,,baz)   o  Add example of percent-encoded key valueA.10.  v06 - v07   o  fixed all issues identified in email from Jernej Tuljak in netconf      email 2015-06-22   o  fixed error example bug where error-urlpath was still used.      Changed to error-path.   o  added mention of YANG Patch and informative reference   o  added support for YANG 1.1, specifically support for anydata and      actions   o  removed the special field value "*", since it is no longer neededA.11.  v05 - v06   o  fixed RESTCONF issue #23 (ietf-restconf-monitoring bug)A.12.  v04 - v05   o  changed term 'notification event' to 'event notification'   o  removed intro text about framework and meta-model   o  removed early mention of API resources   o  removed term unified datastore and cleaned up text about NETCONF      datastores   o  removed text about not immediate persistence of edits   o  removed RESTCONF-specific data-resource-identifier typedef and its      usage   o  clarified encoding of key leafs   o  changed several examples from JSON to XML encoding   o  made 'insert' and 'point' query parameters mandatory to implement   o  removed ":insert" capability URIBierman, et al.         Expires February 16, 2017             [Page 101]Internet-Draft                  RESTCONF                     August 2016   o  renamed stream/encoding to stream/access   o  renamed stream/encoding/type to stream/access/encoding   o  renamed stream/encoding/events to stream/access/location   o  changed XPath from informative to normative reference   o  changed rest-dissertation from normative to informative reference   o  changed example-jukebox playlist 'id' from a data-resource-      identifier to a leafref pointing at the song nameA.13.  v03 - v04   o  renamed 'select' to 'fields' (#1)   o  moved collection resource and page capability to draft-ietf-      netconf-restconf-collection-00 (#3)   o  added mandatory "defaults" protocol capability URI (#4)   o  added optional "with-defaults" query parameter URI (#4)   o  clarified authentication procedure (#9)   o  moved ietf-yang-library module to draft-ietf-netconf-yang-      library-00 (#13)   o  clarified that JSON encoding of module name in a URI MUST follow      the netmod-yang-json encoding rules (#14)   o  added restconf-media-type extension (#15)   o  remove "content" query parameter URI and made this parameter      mandatory (#16)   o  clarified datastore usage   o  changed lock-denied error example   o  added with-defaults query parameter example   o  added term "RESTCONF Capability"   o  changed NETCONF Capability URI registry usage to new RESTCONF      Capability URI Registry usageBierman, et al.         Expires February 16, 2017             [Page 102]Internet-Draft                  RESTCONF                     August 2016A.14.  v02 - v03   o  added collection resource   o  added "page" query parameter capability   o  added "limit" and "offset" query parameters, which are available      if the "page" capability is supported   o  added "stream list" term   o  fixed bugs in some examples   o  added "encoding" list within the "stream" list to allow different      <events> URLs for XML and JSON encoding.   o  made XML MUST implement and JSON MAY implement for servers   o  re-add JSON notification examples (previously removed)   o  updated JSON referencesA.15.  v01 - v02   o  moved query parameter definitions from the YANG module back to the      plain text sections   o  made all query parameters optional to implement   o  defined query parameter capability URI   o  moved 'streams' to new YANG module (ietf-restconf-monitoring)   o  added 'capabilities' container to new YANG module (ietf-restconf-      monitoring)   o  moved 'modules' container to new YANG module (ietf-yang-library)   o  added new leaf 'module-set-id' (ietf-yang-library)   o  added new leaf 'conformance' (ietf-yang-library)   o  changed 'schema' leaf to type inet:uri that returns the location      of the YANG schema (instead of returning the schema directly)   o  changed 'events' leaf to type inet:uri that returns the location      of the event stream resource (instead of returning events      directly)Bierman, et al.         Expires February 16, 2017             [Page 103]Internet-Draft                  RESTCONF                     August 2016   o  changed examples for yang.api resource since the monitoring      information is no longer in this resource   o  closed issue #1 'select parameter' since no objections to the      proposed syntax   o  closed "encoding of list keys" issue since no objection to new      encoding of list keys in a target resource URI.   o  moved open issues list to the issue tracker on githubA.16.  v00 - v01   o  fixed content=nonconfig example (non-config was incorrect)   o  closed open issue 'message-id'.  There is no need for a message-id      field, and RFC 2392 does not apply.   o  closed open issue 'server support verification'.  The headers used      by RESTCONF are widely supported.   o  removed encoding rules from section on RESTCONF Meta-Data.  This      is now defined in "I-D.lhotka-netmod-yang-json".   o  added media type application/yang.errors to map to errors YANG      grouping.  Updated error examples to use new media type.   o  closed open issue 'additional datastores'.  Support may be added      in the future to identify new datastores.   o  closed open issue 'PATCH media type discovery'.  The section on      PATCH has an added sentence on the Accept-Patch header.   o  closed open issue 'YANG to resource mapping'.  Current mapping of      all data nodes to resources will be used in order to allow      mandatory DELETE support.  The PATCH operation is optional, as      well as the YANG Patch media type.   o  closed open issue '_self links for HATEOAS support'.  It was      decided that they are redundant because they can be derived from      the YANG module for the specific data.   o  added explanatory text for the 'select' parameter.   o  added RESTCONF Path Resolution section for discovering the root of      the RESTCONF API using the /.well-known/host-meta.   o  added an "error" media type to for structured error messagesBierman, et al.         Expires February 16, 2017             [Page 104]Internet-Draft                  RESTCONF                     August 2016   o  added Secure Transport section requiring TLS   o  added Security Considerations section   o  removed all references to "REST-like"A.17.  bierman:restconf-04 to ietf:restconf-00   o  updated open issues sectionAppendix B.  Open Issues       -- RFC Ed.: remove this section before publication.   The RESTCONF issues are tracked on github.com:   https://github.com/netconf-wg/restconf/issuesAppendix C.  Example YANG Module   The example YANG module used in this document represents a simple   media jukebox interface.   YANG Tree Diagram for "example-jukebox" ModuleBierman, et al.         Expires February 16, 2017             [Page 105]Internet-Draft                  RESTCONF                     August 2016      +--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    uint32C.1.  example-jukebox YANG Module   module example-jukebox {      namespace "http://example.com/ns/example-jukebox";      prefix "jbox";      organization "Example, Inc.";      contact "support at example.com";      description "Example Jukebox Data Model Module";      revision "2016-08-15" {        description "Initial version.";        reference "example.com document 1-4673";Bierman, et al.         Expires February 16, 2017             [Page 106]Internet-Draft                  RESTCONF                     August 2016      }      identity genre {        description "Base for all genre types";      }      // abbreviated list of genre classifications      identity alternative {        base genre;        description "Alternative music";      }      identity blues {        base genre;        description "Blues music";      }      identity country {        base genre;        description "Country music";      }      identity jazz {        base genre;        description "Jazz music";      }      identity pop {        base genre;        description "Pop music";      }      identity rock {        base genre;        description "Rock music";      }      container jukebox {        presence          "An empty container indicates that the jukebox           service is available";        description          "Represents a jukebox resource, with a library, playlists,           and a play operation.";        container library {          description "Represents the jukebox library resource.";          list artist {            key name;Bierman, et al.         Expires February 16, 2017             [Page 107]Internet-Draft                  RESTCONF                     August 2016            description              "Represents one artist resource within the               jukebox library resource.";            leaf name {              type string {                length "1 .. max";              }              description "The name of the artist.";            }            list album {              key name;              description                "Represents one album resource within one                 artist resource, within the jukebox library.";              leaf name {                type string {                  length "1 .. max";                }                description "The name of the album.";              }              leaf genre {                type identityref { base genre; }                description                  "The genre identifying the type of music on                   the album.";              }              leaf year {                type uint16 {                  range "1900 .. max";                }                description "The year the album was released";              }              container admin {                description                  "Administrative information for the album.";                leaf label {                  type string;                  description "The label that released the album.";                }                leaf catalogue-number {Bierman, et al.         Expires February 16, 2017             [Page 108]Internet-Draft                  RESTCONF                     August 2016                  type string;                  description "The album's catalogue number.";                }              }              list song {                key name;                description                  "Represents one song resource within one                   album resource, within the jukebox library.";                leaf name {                  type string {                     length "1 .. max";                  }                  description "The name of the song";                }                leaf location {                  type string;                  mandatory true;                  description                   "The file location string of the                    media file for the song";                }                leaf format {                  type string;                  description                    "An identifier string for the media type                     for the file associated with the                     'location' leaf for this entry.";                }                leaf length {                  type uint32;                  units "seconds";                  description                    "The duration of this song in seconds.";                }              }   // end list 'song'            }   // end list 'album'          }  // end list 'artist'          leaf artist-count {             type uint32;             units "songs";             config false;             description "Number of artists in the library";          }Bierman, et al.         Expires February 16, 2017             [Page 109]Internet-Draft                  RESTCONF                     August 2016          leaf album-count {             type uint32;             units "albums";             config false;             description "Number of albums in the library";          }          leaf song-count {             type uint32;             units "songs";             config false;             description "Number of songs in the library";          }        }  // end library        list playlist {          key name;          description            "Example configuration data resource";          leaf name {            type string;            description              "The name of the playlist.";          }          leaf description {            type string;            description              "A comment describing the playlist.";          }          list song {            key index;            ordered-by user;            description              "Example nested configuration data resource";            leaf index {    // not really needed              type uint32;              description                "An arbitrary integer index for this playlist song.";            }            leaf id {              type leafref {                path "/jbox:jukebox/jbox:library/jbox:artist/" +                     "jbox:album/jbox:song/jbox:name";              }              mandatory true;Bierman, et al.         Expires February 16, 2017             [Page 110]Internet-Draft                  RESTCONF                     August 2016              description                "Song identifier. Must identify an instance of                 /jukebox/library/artist/album/song/name.";            }          }        }        container player {          description            "Represents the jukebox player resource.";          leaf gap {            type decimal64 {              fraction-digits 1;              range "0.0 .. 2.0";            }            units "tenths of seconds";            description "Time gap between each song";          }        }      }      rpc play {        description "Control function for the jukebox player";        input {          leaf playlist {            type string;            mandatory true;            description "playlist name";          }          leaf song-number {            type uint32;            mandatory true;            description "Song number in playlist to play";          }        }      }   }Appendix D.  RESTCONF Message Examples   The examples within this document use the normative YANG module   "ietf-restconf" defined in Section 8 and the non-normative example   YANG module "example-jukebox" defined in Appendix C.1.   This section shows some typical RESTCONF message exchanges.Bierman, et al.         Expires February 16, 2017             [Page 111]Internet-Draft                  RESTCONF                     August 2016D.1.  Resource Retrieval ExamplesD.1.1.  Retrieve the Top-level API Resource   The client starts by retrieving the RESTCONF root resource:      GET /.well-known/host-meta HTTP/1.1      Host: example.com      Accept: application/xrd+xml   The server might respond:      HTTP/1.1 200 OK      Content-Type: application/xrd+xml      Content-Length: nnn      <XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0'>          <Link rel='restconf' href='/restconf'/>      </XRD>   The client may then retrieve the top-level API resource, using the   root resource "/restconf".      GET /restconf HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond as follows:   [RFC Editor Note: Adjust the date (2016-04-09) for ietf-yang-library   below to the date in the published ietf-yang-library YANG module, and   remove this note.]      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:00 GMT      Server: example-server      Content-Type: application/yang-data+json      {        "ietf-restconf:restconf" : {          "data" : {},          "operations" : {},          "yang-library-version" : "2016-06-21"        }      }   To request that the response content to be encoded in XML, the   "Accept" header can be used, as in this example request:Bierman, et al.         Expires February 16, 2017             [Page 112]Internet-Draft                  RESTCONF                     August 2016      GET /restconf HTTP/1.1      Host: example.com      Accept: application/yang-data-xml   The server will return the same conceptual data either way, which   might be as follows :   [RFC Editor Note: Adjust the date for ietf-yang-library below to the   date in the published ietf-yang-library YANG module, and remove this   note.]      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:00 GMT      Server: example-server      Cache-Control: no-cache      Content-Type: application/yang-data-xml      <restconf xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf">        <data/>        <operations/>        <yang-library-version>2016-06-21</yang-library-version>      </restconf>D.1.2.  Retrieve The Server Module Information   It is possible the YANG library module will change over time.  The   client can retrieve the revision date of the ietf-yang-library   supported by the server from the API resource, as described in the   previous section.   In this example the client is retrieving the modules information from   the server in JSON format:      GET /restconf/data/ietf-yang-library:modules-state HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond as follows:   [RFC Editor Note: Adjust the date for ietf-yang-library below to the   date in the published ietf-yang-library YANG module, and remove this   note.]      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:00 GMT      Server: example-server      Cache-Control: no-cache      Last-Modified: Sun, 22 Apr 2016 01:00:14 GMTBierman, et al.         Expires February 16, 2017             [Page 113]Internet-Draft                  RESTCONF                     August 2016      Content-Type: application/yang-data+json      {        "ietf-yang-library:modules-state" : {          "module-set-id" : "5479120c17a619545ea6aff7aa19838b036ebbd7",          "module" : [            {              "name" : "foo",              "revision" : "2012-01-02",              "schema" : "https://example.com/modules/foo/2012-01-02",              "namespace" : "http://example.com/ns/foo",              "feature" : [ "feature1", "feature2" ],              "deviation" : [                {                  "name" : "foo-dev",                  "revision" "2012-02-16"                }              ],              "conformance-type" : "implement"            },            {              "name" : "ietf-yang-library",              "revision" : "2016-06-21",              "schema" : "https://example.com/modules/\                ietf-yang-library/2016-06-21",              "namespace" :                "urn:ietf:params:xml:ns:yang:ietf-yang-library",              "conformance-type" : "implement"            },            {              "name" : "foo-types",              "revision" : "2012-01-05",              "schema" :                "https://example.com/modules/foo-types/2012-01-05",              "namespace" : "http://example.com/ns/foo-types",              "conformance-type" : "import"            },            {              "name" : "bar",              "revision" : "2012-11-05",              "schema" : "https://example.com/modules/bar/2012-11-05",              "namespace" : "http://example.com/ns/bar",              "feature" : [ "bar-ext" ],              "conformance-type" : "implement",              "submodule" : [                {                  "name" : "bar-submod1",                  "revision" : "2012-11-05",Bierman, et al.         Expires February 16, 2017             [Page 114]Internet-Draft                  RESTCONF                     August 2016                  "schema" :                   "https://example.com/modules/bar-submod1/2012-11-05"                },                {                  "name" : "bar-submod2",                  "revision" : "2012-11-05",                  "schema" :                   "https://example.com/modules/bar-submod2/2012-11-05"                }              ]            }          ]        }      }D.1.3.  Retrieve The Server Capability Information   In this example the client is retrieving the capability information   from the server in XML format, and the server supports all the   RESTCONF query parameters, plus one vendor parameter:      GET /restconf/data/ietf-restconf-monitoring:restconf-state/\          capabilities HTTP/1.1      Host: example.com      Accept: application/yang-data-xml   The server might respond as follows:Bierman, et al.         Expires February 16, 2017             [Page 115]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:02:00 GMT      Server: example-server      Cache-Control: no-cache      Last-Modified: Sun, 22 Apr 2016 01:00:14 GMT      Content-Type: application/yang-data-xml      <capabilities          xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf-monitoring">       <capability>\        urn:ietf:params:restconf:capability:defaults:1.0?\           basic-mode=explicit\       </capability>       <capability>\        urn:ietf:params:restconf:capability:with-defaults:1.0\       </capability>       <capability>\        urn:ietf:params:restconf:capability:depth:1.0\       </capability>       <capability>\        urn:ietf:params:restconf:capability:fields:1.0\       </capability>       <capability>\        urn:ietf:params:restconf:capability:filter:1.0\       </capability>       <capability>\        urn:ietf:params:restconf:capability:start-time:1.0\       </capability>       <capability>\        urn:ietf:params:restconf:capability:stop-time:1.0\       </capability>       <capability>\        http://example.com/capabilities/myparam\       </capability>      </capabilities>D.2.  Edit Resource ExamplesD.2.1.  Create New Data Resources   To create a new "artist" resource within the "library" resource, the   client might send the following request.Bierman, et al.         Expires February 16, 2017             [Page 116]Internet-Draft                  RESTCONF                     August 2016      POST /restconf/data/example-jukebox:jukebox/library HTTP/1.1      Host: example.com      Content-Type: application/yang-data+json      {        "example-jukebox:artist" : [          {            "name" : "Foo Fighters"          }        ]      }   If the resource is created, the server might respond as follows:      HTTP/1.1 201 Created      Date: Mon, 23 Apr 2016 17:02:00 GMT      Server: example-server      Location: https://example.com/restconf/data/\          example-jukebox:jukebox/library/artist=Foo%20Fighters      Last-Modified: Mon, 23 Apr 2016 17:02:00 GMT      ETag: "b3830f23a4c"   To create a new "album" resource for this artist within the "jukebox"   resource, the client might send the following request:      POST /restconf/data/example-jukebox:jukebox/\          library/artist=Foo%20Fighters HTTP/1.1      Host: example.com      Content-Type: application/yang-data-xml      <album xmlns="http://example.com/ns/example-jukebox">        <name>Wasting Light</name>        <year>2011</year>      </album>   If the resource is created, the server might respond as follows:      HTTP/1.1 201 Created      Date: Mon, 23 Apr 2016 17:03:00 GMT      Server: example-server      Location: https://example.com/restconf/data/\          example-jukebox:jukebox/library/artist=Foo%20Fighters/\          album=Wasting%20Light      Last-Modified: Mon, 23 Apr 2016 17:03:00 GMT      ETag: "b8389233a4c"Bierman, et al.         Expires February 16, 2017             [Page 117]Internet-Draft                  RESTCONF                     August 2016D.2.2.  Detect Resource Entity-Tag Change   In this example, the server just supports the datastore last-changed   timestamp.  After the previous request, the client has cached the   "Last-Modified" header and the Location header from the response to   provide in the following request to patch an "album" list entry with   key value "Wasting Light".  Only the "genre" field is being updated.      PATCH /restconf/data/example-jukebox:jukebox/\          library/artist=Foo%20Fighters/album=Wasting%20Light/\          genre HTTP/1.1      Host: example.com      If-Unmodified-Since: Mon, 23 Apr 2016 17:03:00 GMT      Content-Type: application/yang-data+json      { "example-jukebox:genre" : "example-jukebox:alternative" }   In this example the datastore resource has changed since the time   specified in the "If-Unmodified-Since" header.  The server might   respond:      HTTP/1.1 412 Precondition Failed      Date: Mon, 23 Apr 2016 19:01:00 GMT      Server: example-server      Last-Modified: Mon, 23 Apr 2016 17:45:00 GMT      ETag: "b34aed893a4c"D.2.3.  Edit a Datastore Resource   In this example, assume there is a top-level data resource named   "system" from the example-system module, and this container has a   child leaf called "enable-jukebox-streaming":      container system {        leaf enable-jukebox-streaming {          type boolean;        }      }   In this example PATCH is used by the client to modify 2 top-level   resources at once, in order to enable jukebox streaming and add an   "album" sub-resource to eachof 2 "artist" resources:Bierman, et al.         Expires February 16, 2017             [Page 118]Internet-Draft                  RESTCONF                     August 2016      PATCH /restconf/data HTTP/1.1      Host: example.com      Content-Type: application/yang-data-xml      <data xmlns="urn:ietf:params:xml:ns:yang:ietf-restconf">        <system xmlns="http://example.com/ns/example-system">          <enable-jukebox-streaming>true</enable-jukebox-streaming>        </system>        <jukebox xmlns="http://example.com/ns/example-jukebox">          <library>            <artist>              <name>Foo Fighters</name>              <album>                <name>One by One</name>                <year>2012</year>              </album>            </artist>            <artist>              <name>Nick Cave and the Bad Seeds</name>              <album>                <name>Tender Prey</name>                <year>1988</year>              </album>            </artist>          </library>        </jukebox>      </data>D.2.4.  Edit a Data Resource   In this example, the client modifies one data node by adding an   "album" sub-resource by sending a PATCH for the data resource:      PATCH /restconf/data/example-jukebox:jukebox/library/\         artist=Nick%20Cave%20and%20the%Bad%20Seeds HTTP/1.1      Host: example.com      Content-Type: application/yang-data-xml      <artist xmlns="http://example.com/ns/example-jukebox">        <name>Nick Cave and the Bad Seeds</name>        <album>          <name>The Good Son</name>          <year>1990</year>        </album>      </artist>Bierman, et al.         Expires February 16, 2017             [Page 119]Internet-Draft                  RESTCONF                     August 2016D.3.  Query Parameter ExamplesD.3.1.  "content" Parameter   The "content" parameter is used to select the type of data child   resources (configuration and/or not configuration) that are returned   by the server for a GET method request.   In this example, a simple YANG list that has configuration and non-   configuration child resources.     container events       list event {         key name;         leaf name { type string; }         leaf description { type string; }         leaf event-count {           type uint32;           config false;         }       }     }   Example 1: content=all   To retrieve all the child resources, the "content" parameter is set   to "all", or omitted, since this is the default value.  The client   might send:      GET /restconf/data/example-events:events?\          content=all HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond:Bierman, et al.         Expires February 16, 2017             [Page 120]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:11:30 GMT      Server: example-server      Cache-Control: no-cache      Content-Type: application/yang-data+json      {        "example-events:events" : {          "event" : [            {              "name" : "interface-up",              "description" : "Interface up notification count",              "event-count" : 42            },            {              "name" : "interface-down",              "description" : "Interface down notification count",              "event-count" : 4            }          ]        }      }   Example 2: content=config   To retrieve only the configuration child resources, the "content"   parameter is set to "config".  Note that the "ETag" and   "Last-Modified" headers are only returned if the content parameter   value is "config".      GET /restconf/data/example-events:events?\          content=config HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond:Bierman, et al.         Expires February 16, 2017             [Page 121]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:11:30 GMT      Server: example-server      Last-Modified: Mon, 23 Apr 2016 13:01:20 GMT      ETag: "eeeada438af"      Cache-Control: no-cache      Content-Type: application/yang-data+json      {        "example-events:events" : {          "event" : [            {              "name" : "interface-up",              "description" : "Interface up notification count"            },            {              "name" : "interface-down",              "description" : "Interface down notification count"            }          ]        }      }   Example 3: content=nonconfig   To retrieve only the non-configuration child resources, the "content"   parameter is set to "nonconfig".  Note that configuration ancestors   (if any) and list key leafs (if any) are also returned.  The client   might send:      GET /restconf/data/example-events:events?\         content=nonconfig HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond:Bierman, et al.         Expires February 16, 2017             [Page 122]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:11:30 GMT      Server: example-server      Cache-Control: no-cache      Content-Type: application/yang-data+json      {        "example-events:events" : {          "event" : [            {              "name" : "interface-up",              "event-count" : 42            },            {              "name" : "interface-down",              "event-count" : 4            }          ]        }      }D.3.2.  "depth" Parameter   The "depth" parameter is used to limit the number of levels of child   resources that are returned by the server for a GET method request.   The depth parameter starts counting levels at the level of the target   resource that is specified, so that a depth level of "1" includes   just the target resource level itself.  A depth level of "2" includes   the target resource level and its child nodes.   This example shows how different values of the "depth" parameter   would affect the reply content for retrieval of the top-level   "jukebox" data resource.   Example 1: depth=unbounded   To retrieve all the child resources, the "depth" parameter is not   present or set to the default value "unbounded".      GET /restconf/data/example-jukebox:jukebox?\          depth=unbounded HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond:      HTTP/1.1 200 OKBierman, et al.         Expires February 16, 2017             [Page 123]Internet-Draft                  RESTCONF                     August 2016      Date: Mon, 23 Apr 2016 17:11:30 GMT      Server: example-server      Cache-Control: no-cache      Content-Type: application/yang-data+json      {        "example-jukebox:jukebox" : {          "library" : {            "artist" : [              {                "name" : "Foo Fighters",                "album" : [                  {                    "name" : "Wasting Light",                    "genre" : "example-jukebox:alternative",                    "year" : 2011,                    "song" : [                      {                        "name" : "Wasting Light",                        "location" :                          "/media/foo/a7/wasting-light.mp3",                        "format" : "MP3",                        "length" " 286                      },                      {                        "name" : "Rope",                        "location" : "/media/foo/a7/rope.mp3",                        "format" : "MP3",                        "length" " 259                      }                    ]                  }                ]              }            ]          },          "playlist" : [            {              "name" : "Foo-One",              "description" : "example playlist 1",              "song" : [                {                  "index" : 1,                  "id" : "https://example.com/restconf/data/                        example-jukebox:jukebox/library/artist=                        Foo%20Fighters/album=Wasting%20Light/                        song=Rope"                },Bierman, et al.         Expires February 16, 2017             [Page 124]Internet-Draft                  RESTCONF                     August 2016                {                  "index" : 2,                  "id" : "https://example.com/restconf/data/                        example-jukebox:jukebox/library/artist=                        Foo%20Fighters/album=Wasting%20Light/song=                        Bridge%20Burning"                }              ]            }          ],          "player" : {            "gap" : 0.5          }        }      }   Example 2: depth=1   To determine if 1 or more resource instances exist for a given target   resource, the value one is used.      GET /restconf/data/example-jukebox:jukebox?depth=1 HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond:      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:11:30 GMT      Server: example-server      Cache-Control: no-cache      Content-Type: application/yang-data+json      {        "example-jukebox:jukebox" : {}      }   Example 3: depth=3   To limit the depth level to the target resource plus 2 child resource   layers the value "3" is used.      GET /restconf/data/example-jukebox:jukebox?depth=3 HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond:Bierman, et al.         Expires February 16, 2017             [Page 125]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:11:30 GMT      Server: example-server      Cache-Control: no-cache      Content-Type: application/yang-data+json      {        "example-jukebox:jukebox" : {          "library" : {            "artist" : {}          },          "playlist" : [            {              "name" : "Foo-One",              "description" : "example playlist 1",              "song" : {}            }          ],          "player" : {            "gap" : 0.5          }        }      }D.3.3.  "fields" Parameter   In this example the client is retrieving the datastore resource in   JSON format, but retrieving only the "modules-state/module" list, and   only the "name" and "revision" nodes from each list entry.  Note that   top node returned by the server matches the target resource node   (which is "data" in this example).  The "module-set-id" leaf is not   returned because it is not selected in the fields expression.      GET /restconf/data?fields=ietf-yang-library:modules-state/\          module(name;revision) HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond as follows.   [RFC Editor Note: Adjust the date for ietf-yang-library below to the   date in the published ietf-yang-library YANG module, and remove this   note.]   [RFC Editor Note: Adjust the date for ietf-restconf-monitoring below   to the date in the published ietf-restconf-monitoring YANG module,   and remove this note.]Bierman, et al.         Expires February 16, 2017             [Page 126]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:00 GMT      Server: example-server      Content-Type: application/yang-data+json      {        "ietf-restconf:data" : {          "ietf-yang-library:modules-state" : {            "module" : [              {                "name" : "example-jukebox",                "revision" : "2015-06-04"              },              {                "name" : "ietf-inet-types",                "revision" : "2013-07-15"              },              {                "name" : "ietf-restconf-monitoring",                "revision" : "2016-03-16"              },              {                "name" : "ietf-yang-library",                "revision" : "2016-04-09"              },              {                "name" : "ietf-yang-types",                "revision" : "2013-07-15"              }            ]          }        }      }D.3.4.  "insert" Parameter   In this example, a new first song entry in the "Foo-One" playlist is   being created.   Request from client:Bierman, et al.         Expires February 16, 2017             [Page 127]Internet-Draft                  RESTCONF                     August 2016      POST /restconf/data/example-jukebox:jukebox/\          playlist=Foo-One?insert=first HTTP/1.1      Host: example.com      Content-Type: application/yang-data+json      {        "example-jukebox:song" : [           {             "index" : 1,             "id" : "/example-jukebox:jukebox/library/\                artist=Foo%20Fighters/album=Wasting%20Light/song=Rope"           }         ]      }   Response from server.      HTTP/1.1 201 Created      Date: Mon, 23 Apr 2016 13:01:20 GMT      Server: example-server      Last-Modified: Mon, 23 Apr 2016 13:01:20 GMT      Location: https://example.com/restconf/data/\          example-jukebox:jukebox/playlist=Foo-One/song=1      ETag: "eeeada438af"D.3.5.  "point" Parameter   In this example, the client is inserting a new "song" resource within   an "album" resource after another song.   Request from client:Bierman, et al.         Expires February 16, 2017             [Page 128]Internet-Draft                  RESTCONF                     August 2016      POST /restconf/data/example-jukebox:jukebox/\          library/artist=Foo%20Fighters/album=Wasting%20Light?\          insert=after&point=%2Fexample-jukebox%3Ajukebox%2F\          library%2Fartist%3DFoo%20Fighters%2Falbum%3D\          Wasting%20Light%2Fsong%3DBridge%20Burning HTTP/1.1      Host: example.com      Content-Type: application/yang-data+json      {        "example-jukebox:song" : [          {            "name" : "Rope",            "location" : "/media/foo/a7/rope.mp3",            "format" : "MP3",            "length" : 259          }        ]      }   Response from server:      HTTP/1.1 204 No Content      Date: Mon, 23 Apr 2016 13:01:20 GMT      Server: example-server      Last-Modified: Mon, 23 Apr 2016 13:01:20 GMT      ETag: "abcada438af"D.3.6.  "filter" Parameter   The following URIs show some examples of notification filter   specifications:Bierman, et al.         Expires February 16, 2017             [Page 129]Internet-Draft                  RESTCONF                     August 2016      // filter = /event/event-class='fault'      GET /streams/NETCONF?filter=%2Fevent%2Fevent-class%3D'fault'      // filter = /event/severity<=4      GET /streams/NETCONF?filter=%2Fevent%2Fseverity%3C%3D4      // filter = /linkUp|/linkDown      GET /streams/SNMP?filter=%2FlinkUp%7C%2FlinkDown      // filter = /*/reporting-entity/card!='Ethernet0'      GET /streams/NETCONF?\         filter=%2F*%2Freporting-entity%2Fcard%21%3D'Ethernet0'      // filter = /*/email-addr[contains(.,'company.com')]      GET /streams/critical-syslog?\         filter=%2F*%2Femail-addr[contains(.%2C'company.com')]      // Note: the module name is used as prefix.      // filter = (/example-mod:event1/name='joe' and      //           /example-mod:event1/status='online')      GET /streams/NETCONF?\        filter=(%2Fexample-mod%3Aevent1%2Fname%3D'joe'%20and\                %20%2Fexample-mod%3Aevent1%2Fstatus%3D'online')      // To get notifications from just two modules (e.g., m1 + m2)      // filter=(/m1:* or /m2:*)      GET /streams/NETCONF?filter=(%2Fm1%3A*%20or%20%2Fm2%3A*)D.3.7.  "start-time" Parameter   The following URI shows an example of the "start-time" query   parameter:      // start-time = 2014-10-25T10:02:00Z      GET /streams/NETCONF?start-time=2014-10-25T10%3A02%3A00ZD.3.8.  "stop-time" Parameter   The following URI shows an example of the "stop-time" query   parameter:      // start-time = 2014-10-25T10:02:00Z      // stop-time = 2014-10-25T12:31:00Z      GET /mystreams/NETCONF?start-time=2014-10-25T10%3A02%3A00Z\         &stop-time=2014-10-25T12%3A31%3A00ZBierman, et al.         Expires February 16, 2017             [Page 130]Internet-Draft                  RESTCONF                     August 2016D.3.9.  "with-defaults" Parameter   Assume the server implements the module "example" defined in   Appendix A.1 of [RFC6243].  Assume the server's datastore is as   defined in Appendix A.2 of [RFC6243].   If the server defaults-uri basic-mode is "trim", the the following   request for interface "eth1" might be as follows:   Without query parameter:      GET /restconf/data/example:interfaces/interface=eth1 HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond as follows.      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:00 GMT      Server: example-server      Content-Type: application/yang-data+json      {        "example:interface" : [          {            "name" : "eth1",            "status" : "up"          }        ]      }   Note that the "mtu" leaf is missing because it is set to the default   "1500", and the server defaults handling basic-mode is "trim".   With query parameter:      GET /restconf/data/example:interfaces/interface=eth1\          ?with-defaults=report-all HTTP/1.1      Host: example.com      Accept: application/yang-data+json   The server might respond as follows.Bierman, et al.         Expires February 16, 2017             [Page 131]Internet-Draft                  RESTCONF                     August 2016      HTTP/1.1 200 OK      Date: Mon, 23 Apr 2016 17:01:00 GMT      Server: example-server      Content-Type: application/yang-data+json      {        "example:interface" : [          {            "name" : "eth1",            "mtu" : 1500,            "status" : "up"          }        ]      }   Note that the server returns the "mtu" leaf because the "report-all"   mode was requested with the "with-defaults" query parameter.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.netBierman, et al.         Expires February 16, 2017             [Page 132]