YANG PUBSUB Proposal

Owned by Manish Kumar Barnwal
Jun 20, 2021
2 min read

Name

YANG PUBSUB

Repo Name

yang-push

Description

The YANG PUBSUB project allows subscriptions to be placed on targeted subtrees of YANG datastores residing on remote devices. Changes in YANG objects within the remote subtree can be pushed to an OpenDaylight controller as specified without a requiring the controller to make a continuous set of fetch requests.

Iterative fetching of data is not an adequate solution for applications requiring frequent or prompt updates of remote object state. Reasons include:

  • Trying to impose a polling based solution to this problem imposes load on networks, controllers, routers, and applications.

  • The propagation latency achievable with polling can be undesirably slow for some applications.

  • Polling solutions are brittle in the face of communication glitches, and they have limitations in their ability to synchronize and calibrate retrieval intervals across a network.

A full set of requirements and reasoning can be found in the IETF's I2RS PubSub requirements. A solution to these requirements is being worked in the NETCONF WG (see draft-clemm-netconf-yang-push). A high level overview of this solution is below.

Incorporating OpenDaylight code able to access a yang-push compliant datastore will enable a controller to avoid the issues listed above. Based on criteria negotiated as part of such a subscription, updates will be pushed to a controller. Negotiable subscription criteria include:

  • whether changes should be sent as they are made on the remote device (on-change), or

  • whether changes should be sent on recurring intervals (periodic).

  • Subtree or XPATH filters to eliminate unneeded objects from a pushed update

  • Additional parameters as described in draft-clemm-netconf-yang-push

Scope

The intent is to have all code being able to integrate with the IETF draft in the IETF NETCONF WG.

  • Client implementation which can operate with a draft-clemm-netconf-yang-push compliant datastore

  • Enhance Netconf protocol client API to enable data subscription

Other components affected/used by this proposal include:

  • Controller

  • NETCONF

Resources Committed (developers committed to working)

  • Ambika Prasad Tripathy

  • Suryamani Kar

  • Eric Voit

  • Alexander Clemm

  • Einar Nilsen-Nygaard

  • Swaroop Shastri

  • Reena Kohli

  • Janosch Klein

  • Jayashankar T

Initial Committers

Vendor Neutral

  • No vendor package names in code

  • No vendor branding / trademark present in code or output of build

  • No vendor branding / trademark present in documentation

Meets Board Policy (including IPR)

Presentation

File:ODL-Beryllium-YANG-PUB-SUB.pptx