Requirements for Subscription to YANG Datastores
RFC 7923

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Internet Engineering Task Force (IETF)                           E. Voit
Request for Comments: 7923                                      A. Clemm
Category: Informational                               A. Gonzalez Prieto
ISSN: 2070-1721                                            Cisco Systems
                                                               June 2016

            Requirements for Subscription to YANG Datastores

Abstract

   This document provides requirements for a service that allows client
   applications to subscribe to updates of a YANG datastore.  Based on
   criteria negotiated as part of a subscription, updates will be pushed
   to targeted recipients.  Such a capability eliminates the need for
   periodic polling of YANG datastores by applications and fills a
   functional gap in existing YANG transports (i.e., Network
   Configuration Protocol (NETCONF) and RESTCONF).  Such a service can
   be summarized as a "pub/sub" service for YANG datastore updates.
   Beyond a set of basic requirements for the service, various
   refinements are addressed.  These refinements include: periodicity of
   object updates, filtering out of objects underneath a requested a
   subtree, and delivery QoS guarantees.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7923.

Voit, et al.                  Informational                     [Page 1]
RFC 7923             YANG Subscription Requirements            June 2016

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
   2. Business Drivers ................................................3
      2.1. Pub/Sub in the Interface to the Routing System (I2RS) ......4
      2.2. Pub/Sub Variants on Network Elements .......................5
      2.3. Existing Generalized Pub/Sub Implementations ...............6
   3. Terminology .....................................................6
   4. Requirements ....................................................7
      4.1. Assumptions for Subscriber Behavior ........................7
      4.2. Subscription Service Requirements ..........................8
           4.2.1. General .............................................8
           4.2.2. Negotiation .........................................9
           4.2.3. Update Distribution ................................10
           4.2.4. Transport ..........................................11
           4.2.5. Security Requirements ..............................11
           4.2.6. Subscription QoS ...................................13
           4.2.7. Filtering ..........................................14
           4.2.8. Assurance and Monitoring ...........................15
   5. Security Considerations ........................................15
   6. References .....................................................16
      6.1. Normative References ......................................16
      6.2. Informative References ....................................16
   Acknowledgments ...................................................17
   Authors' Addresses ................................................18

Voit, et al.                  Informational                     [Page 2]
RFC 7923             YANG Subscription Requirements            June 2016

1.  Introduction

   Applications interacting with YANG datastores require capabilities
   beyond the traditional client-server configuration of network
   elements.  One class of such applications are service-assurance
   applications, which must maintain a continuous view of operational
   data and state.  Another class of applications are security