Cm Subscriptions Docs

- Included documentation for an overview of Cm Data Subscription for the
  Create and Delete use case.
- Only included the json schemas for the events that are coming in and
  going out of NCMP.
- Not mentioning anything abt the internal events we use between DMIs.
- The docs can later be used to explain abt the notifications when they
  are implemented.

Issue-ID: CPS-2324
Change-Id: I2497656e0e56c93054b7e92b1742a668463c3ffc
Signed-off-by: mpriyank <priyank.maheshwari@est.tech>

1 files changed, 48 insertions, 0 deletions

diff --git a/docs/cm-notification-subscriptions.rst b/docs/cm-notification-subscriptions.rst
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+.. This work is licensed under a Creative Commons Attribution 4.0 International License.
+.. http://creativecommons.org/licenses/by/4.0
+.. Copyright (C) 2024 Nordix Foundation
+
+.. DO NOT CHANGE THIS LABEL FOR RELEASE NOTES - EVEN THOUGH IT GIVES A WARNING
+.. _cmNotificationSubscriptions:
+
+
+CM Data Subscriptions
+#####################
+
+.. toctree::
+   :maxdepth: 1
+
+Introduction
+============
+CM Subscriptions are created to subscribe to notifications for CM related changes that happened in the network based on predicates.
+Predicates can be used to filter on CM Handle (id), Datastore and Xpath.
+
+The CM Subscription flow is event driven and adheres to the CNCF Cloud Events Specifications.
+
+Event to create and delete a subscription.
+
+:download:`CM Subscription Event Schema <schemas/ncmp-in-event-schema-1.0.0.json>`
+
+Event to receive status of participants in a subscription.
+
+:download:`CM Subscription Response Event Schema <schemas/ncmp-out-event-schema-1.0.0.json>`
+
+CM Subscriptions Creation
+-------------------------
+To create a subscription, a client sends an event to a configured topic to register its interest with NCMP allowing the client to receive notifications based on the subscription.
+
+CM Subscriptions Deletion
+-------------------------
+If a client no longer wishes to receive notifications based on a registered subscription, the client can delete the subscription by providing the subscription id.
+
+CM Subscriptions Response
+-------------------------
+The response for the involved subscription participants for the Create and Delete flow can be as follows based on how the DMI Plugin responds back to NCMP.
+    - **ACCEPTED:** DMI Plugin successfully applied the subscription.
+    - **REJECTED:** DMI Plugin failed to apply the subscription.
+    - **PENDING:** DMI Plugin failed to respond within a configured time.
+
+**Note.** The Cm Subscription feature relies on the DMI Plugin support for applying the subscriptions. This support is currently not implemented in the ONAP DMI Plugin.
+
+
+