NETCONF Working Group K. Watsen Internet-Draft Watsen Networks Updates: 8040 (if approved) Q. Wu Intended status: Standards Track Huawei Technologies Expires: 28 April 2022 O. Hagsand Netgate H. Li Hewlett Packard Enterprise P. Andersson Cisco Systems 25 October 2021 RESTCONF Extensions to Support List Pagination draft-wwlh-netconf-list-pagination-rc-02 Abstract This document defines a mapping of the list pagination mechanism defined in [I-D.wwlh-netconf-list-pagination] to RESTCONF [RFC8040]. This document updates RFC 8040, to declare "list" and "leaf-list" as valid resource targets for the RESTCONF GET and DELETE operations, to define GET query parameters necessary for list pagination, and to define a media-type for XML-based lists. 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 https://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 28 April 2022. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. Watsen, et al. Expires 28 April 2022 [Page 1] Internet-Draft RESTCONF Pagination Support October 2021 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 3 2. Updates to RFC 8040 . . . . . . . . . . . . . . . . . . . . . 3 2.1. Resource Targets . . . . . . . . . . . . . . . . . . . . 3 2.2. Media Type . . . . . . . . . . . . . . . . . . . . . . . 3 2.3. Query Parameters . . . . . . . . . . . . . . . . . . . . 4 2.3.1. The "limit" Query Parameter . . . . . . . . . . . . . 5 2.3.2. The "offset" Query Parameter . . . . . . . . . . . . 5 2.3.3. The "direction" Query Parameter . . . . . . . . . . . 5 2.3.4. The "sort-by" Query Parameter . . . . . . . . . . . . 6 2.3.5. The "where" Query Parameter . . . . . . . . . . . . . 6 2.3.6. The "sublist-limit" Query Parameter . . . . . . . . . 6 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 3.1. The "RESTCONF Capability URNs" Registry . . . . . . . . . 6 3.2. The "Media Types" Registry . . . . . . . . . . . . . . . 7 3.2.1. Media Type "application/yang-data+xml-list" . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. Normative References . . . . . . . . . . . . . . . . . . 8 5.2. Informative References . . . . . . . . . . . . . . . . . 9 Appendix A. Example YANG Module . . . . . . . . . . . . . . . . 9 Appendix B. Example Data Set . . . . . . . . . . . . . . . . . . 9 Appendix C. Example Queries . . . . . . . . . . . . . . . . . . 9 C.1. List pagination with all query parameters . . . . . . . . 9 C.2. Deletion of a list . . . . . . . . . . . . . . . . . . . 11 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 1. Introduction This document defines a mapping of the list pagination mechanism defined in [I-D.wwlh-netconf-list-pagination] to RESTCONF [RFC8040]. This document updates RFC 8040, as described in Section 2. Watsen, et al. Expires 28 April 2022 [Page 2] Internet-Draft RESTCONF Pagination Support October 2021 Declaring "list" and "leaf-list" as valid resource targets for the GET operation is necessary for list pagination. Declaring these nodes as valid resource targets for the DELETE operation merely completes the solution for RESTCONF. 1.1. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 1.2. Conventions Various examples used in this document use a placeholder value for binary data that has been base64 encoded (e.g., "BASE64VALUE="). This placeholder value is used as real base64 encoded structures are often many lines long and hence distracting to the example being presented. 2. Updates to RFC 8040 2.1. Resource Targets This document extends Section 3.5 of [RFC8040] to add "list" and "leaf-list" nodes (not just their entries) as valid data resources for the "GET" and "DELETE" operations. 2.2. Media Type This document extends Section 3.2 of [RFC8040] to add a new media type, "application/yang-data+xml-list", to encode "list" and "leaf- list" nodes in XML. The "application/yang-data+xml-list" media-type defines a pseudo top- level element called "xml-list" that is used to wrap the response set, thus ensuring that a single top-level element is returned for the XML encoding", as required by Section 4.3 of [RFC8040]. For JSON, the existing "application/yang-data+json" media type is sufficient, as the JSON format has built-in support for encoding arrays. The "application/yang-data+xml-list" media type is registered in Section 3.2.1. Watsen, et al. Expires 28 April 2022 [Page 3] Internet-Draft RESTCONF Pagination Support October 2021 2.3. Query Parameters This document extends Section 4.8 of [RFC8040] to add new query parameters "limit", "offset", "direction", "sort-by", "where", and "sublist-list". These six query parameters correspond to those defined in Sections 3.1 and 3.2 in [I-D.wwlh-netconf-list-pagination]. +-----------+---------+-----------------------------------------+ | Name | Methods | Description | +-----------+---------+-----------------------------------------+ | limit | GET, | Limits the number of entries returned. | | | HEAD | If not specified, the number of entries | | | | that may be returned is unbounded. | | | | | | offset | GET, | Indicates the number of entries in the | | | HEAD | result set that should the skipped over | | | | when preparing the response. If not | | | | specified, then no entries in the | | | | result set are skipped. | | | | | | direction | GET, | Indicates the direction that the result | | | HEAD | set is to be traversed. If not | | | | specified, then the result set is | | | | traversed in the "forwards" direction. | | | | | | sort-by | GET, | Indicates the node name that the result | | | HEAD | set should be sorted by. If not | | | | specified, then the result set's | | | | default order is used, per YANG's | | | | "ordered-by" statement. | | | | | | where | GET, | Specifies a filter expression that | | | HEAD | result set entries must match. If | | | | not specified, then no entries are | | | | filtered from the result set. | | | | | | sublist- | GET, | Limits the number of entries returned | | limit | HEAD | returned for descendent lists and | | | | leaf-lists. If not specified, the | | | | number of entries that may be returned | | | | is unbounded. | +-----------+---------+-----------------------------------------+ Watsen, et al. Expires 28 April 2022 [Page 4] Internet-Draft RESTCONF Pagination Support October 2021 For all of the query parameters, the query parameter is only allowed for the GET and HEAD methods on "list" and "leaf-list" data resources. A "400 Bad Request" status-line MUST be returned if used with any other method or resource type. The error-tag value "operation-not-supported" is used in this case. Per the conformance defined in Section 3.1 of [I-D.wwlh-netconf-list-pagination], all of these parameters MUST be supported for all lists and leaf-lists, but servers MAY disable the support for some or all "config false" lists, as described in Section 3.3 of [I-D.wwlh-netconf-list-pagination]. 2.3.1. The "limit" Query Parameter The "limit" query parameter corresponds to the "limit" parameter defined in Section 3.1.5 of [I-D.wwlh-netconf-list-pagination]. If the limit value is invalid, then a "400 Bad Request" status-line MUST be returned with the error-type value "application" and error- tag value "invalid-value". 2.3.2. The "offset" Query Parameter The "offset" query parameter corresponds to the "offset" parameter defined in Section 3.1.4 of [I-D.wwlh-netconf-list-pagination]. If the offset value is invalid, a "400 Bad Request" status-line MUST be returned with the error-type value "application" and error-tag value "invalid-value". If the offset value exceeds the number of entries in the working result set, then a "416 Range Not Satisfiable" status-line MUST be returned with the error-type value "application", error-tag value "invalid-value", and SHOULD also include the "offset-out-of-range" identity as error-app-tag value. 2.3.3. The "direction" Query Parameter The "direction" query parameter corresponds to the "direction" parameter defined in Section 3.1.3 of [I-D.wwlh-netconf-list-pagination]. If the direction value is invalid, then a "400 Bad Request" status- line MUST be returned with the error-type value "application" and error-tag value "invalid-value". Watsen, et al. Expires 28 April 2022 [Page 5] Internet-Draft RESTCONF Pagination Support October 2021 2.3.4. The "sort-by" Query Parameter The "sort-by" query parameter corresponds to the "sort-by" parameter defined in Section 3.1.2 of [I-D.wwlh-netconf-list-pagination]. If the specified node identifier is invalid, then a "400 Bad Request" status-line MUST be returned with the error-type value "application" and error-tag value "invalid-value". 2.3.5. The "where" Query Parameter The "where" query parameter corresponds to the "where" parameter defined in Section 3.1.1 of [I-D.wwlh-netconf-list-pagination]. If the specified XPath expression is invalid, then a "400 Bad Request" status-line MUST be returned with the error-type value "application" and error-tag value "invalid-value". 2.3.6. The "sublist-limit" Query Parameter The "sublist-limit" query parameter corresponds to the "sublist- limit" parameter defined in Section 3.2.1 of [I-D.wwlh-netconf-list-pagination]. If the sumlist-limit value is invalid, then a "400 Bad Request" status-line MUST be returned with the error-type value "application" and error-tag value "invalid-value". 3. IANA Considerations 3.1. The "RESTCONF Capability URNs" Registry This document registers six capabilities in the RESTCONF Capability URNs [RFC8040] maintained at https://www.iana.org/assignments/ restconf-capability-urns/restconf-capability-urns.xhtml. Following the instructions defined in Section 11.4 of [RFC8040], the below registrations are requested: All the registrations are to use this document (RFC XXXX) for the "Reference" value. Watsen, et al. Expires 28 April 2022 [Page 6] Internet-Draft RESTCONF Pagination Support October 2021 Index Capability Identifier --------------------------------------------------------------------- :limit urn:ietf:params:restconf:capability:limit:1.0 :offset urn:ietf:params:restconf:capability:offset:1.0 :direction urn:ietf:params:restconf:capability:direction:1.0 :sort-by urn:ietf:params:restconf:capability:sort-by:1.0 :where urn:ietf:params:restconf:capability:where:1.0 :sublist-limit urn:ietf:params:restconf:capability:sublist-limit:1.0 3.2. The "Media Types" Registry This document registers one media type in the "application" subregistry of the Media Types registry [RFC6838] [RFC4855] maintained at https://www.iana.org/assignments/media-types/media- types.xhtml#application. Following the format defined in [RFC4855], the below registration is requested: 3.2.1. Media Type "application/yang-data+xml-list" Type name: application Subtype name: yang-data+xml-list Required parameters: None Optional parameters: None 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 [RFC7950]. Security considerations: Security considerations related to the generation and consumption of RESTCONF messages are discussed in Section 12 of RFC 8040. 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. Interoperability considerations: RFC XXXX specifies the format of conforming messages and the interpretation thereof. Published specification: RFC XXXX Applications that use this media type: Instance document data parsers used within a protocol or automation tool that Watsen, et al. Expires 28 April 2022 [Page 7] Internet-Draft RESTCONF Pagination Support October 2021 utilize the YANG Patch data structure. Fragment identifier considerations: Fragment identifiers for this type are not defined. All YANG data nodes are accessible as resources using the path in the request URI. Additional information: Deprecated alias names for this type: N/A Magic number(s): N/A File extension(s): None Macintosh file type code(s): "TEXT" Person & email address to contact for further information: See the Authors' Addresses section of RFC XXXX. Intended usage: COMMON Restrictions on usage: N/A Author: See the Authors' Addresses section of RFC XXXX. Change controller: Internet Engineering Task Force (mailto:iesg@ietf.org). Provisional registration? (standards tree only): no 4. Security Considerations This document introduces protocol operations for paging through data already provided by the RESTCONF protocol, and hence does not introduce any new security considerations. This document does not define a YANG module and hence there are no data modeling considerations beyond those discussed in [I-D.wwlh-netconf-list-pagination]. 5. References 5.1. Normative References [I-D.wwlh-netconf-list-pagination] "List Pagination...", . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Watsen, et al. Expires 28 April 2022 [Page 8] Internet-Draft RESTCONF Pagination Support October 2021 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 5.2. Informative References [I-D.ietf-netconf-restconf-collection] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Collection Resource", Work in Progress, Internet-Draft, draft-ietf-netconf-restconf-collection-00, 30 January 2015, . [RFC4855] Casner, S., "Media Type Registration of RTP Payload Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007, . [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type Specifications and Registration Procedures", BCP 13, RFC 6838, DOI 10.17487/RFC6838, January 2013, . Appendix A. Example YANG Module The examples within this document use the "example-social" YANG module defined in Appendix A.1 of [I-D.wwlh-netconf-list-pagination]. Appendix B. Example Data Set The Example Data Set used by the examples is defined in Appendix A.2 of [I-D.wwlh-netconf-list-pagination]. Appendix C. Example Queries C.1. List pagination with all query parameters This example mimics that Appendix A.3.7 of [I-D.wwlh-netconf-list-pagination]. Watsen, et al. Expires 28 April 2022 [Page 9] Internet-Draft RESTCONF Pagination Support October 2021 =============== NOTE: '\' line wrapping per RFC 8792 ================ GET /restconf/ds/ietf-datastores:running/example-social:members/memb\ er?where=//stats//joined[starts-with(@timestamp,'2020')]&sort-by=tim\ estamp&direction=backwards&offset=2&limit=2&sublist-limit=1 HTTP/1.1 Host: example.com Accept: application/yang-data+xml-list Response from the RESTCONF server: =============== NOTE: '\' line wrapping per RFC 8792 ================ HTTP/1.1 200 OK Date: Thu, 26 Jan 2017 20:56:30 GMT Server: example-server Last-Modified: Thu, 26 Jan 2017 20:55:30 GMT Content-Type: application/yang-data+xml-list eric eric@example.com $0$1543 BASE64VALUE= Go to bed with dreams; wake up with a purpose. alice 2020-09-17T18:02:04Z Son, brother, husband, father What's your story? two 2020-09-17T19:38:32Z pro 2020-09-17T18:02:04Z bob bob@example.com $0$1543 Watsen, et al. Expires 28 April 2022 [Page 10] Internet-Draft RESTCONF Pagination Support October 2021 BASE64VALUE= Here and now, like never before. 2020-08-14T03:32:25Z Just got in. 3.14159 2020-08-14T03:30:00Z standard 2020-08-14T03:34:30Z C.2. Deletion of a list This example illustrates using a "list" as the DELETE target. =============== NOTE: '\' line wrapping per RFC 8792 ================ DELETE /restconf/ds/ietf-datastores:running/example-social:members/m\ ember=bob/favorites/decimal64-numbers HTTP/1.1 Host: example.com Accept: application/yang-data+xml Response from the RESTCONF server: HTTP/1.1 204 No Content Date: Thu, 26 Jan 2017 20:56:30 GMT Server: example-server Acknowledgements This work has benefited from the discussions of restconf resource collection over the years, in particular, [I-D.ietf-netconf-restconf-collection]. The authors additionally thank the following for lively discussions on list (ordered by first name): Andy Bierman, Martin Bjoerklund, and Robert Varga Authors' Addresses Watsen, et al. Expires 28 April 2022 [Page 11] Internet-Draft RESTCONF Pagination Support October 2021 Kent Watsen Watsen Networks Email: kent+ietf@watsen.net Qin Wu Huawei Technologies 101 Software Avenue, Yuhua District Nanjing Jiangsu, 210012 China Email: bill.wu@huawei.com Olof Hagsand Netgate Email: olof@hagsand.se Hongwei Li Hewlett Packard Enterprise Email: flycoolman@gmail.com Per Andersson Cisco Systems Email: perander@cisco.com Watsen, et al. Expires 28 April 2022 [Page 12]