.. This work is licensed under a Creative Commons Attribution 4.0
   International License. http://creativecommons.org/licenses/by/4.0
   
.. _docs_slice_analysis_ms_overview:

Architecture
------------
The internal architecture of Slice Analysis MS is shown below.

.. image:: ./slice_analysis_ms_arch.jpg

The Slice Analysis MS has a DMaaP interface towards towards Policy and VES-Collector, and a REST
interface towards Config DB. It also has a DMaaP interface to receive any recommendations for
Closed Loop updates from an ML engine, which is then used to trigger a control loop message to
Policy.

- **DMAAP Client** creates a thread pool for every DMaaP topic consumer. The thread
  polls the DMaaP topic for every configured time interval and whenever a message is
  received it stores that message in the Postgres DB.

- **PM Thread** reads the PM event from the database and puts the PM sample in the
  internal queue in the format which is needed for further processing.

- **Consumer Thread** consumes PM samples from the internal queue and make all the
  required Config DB calls, perform the analysis, and puts the onset message to the DMaaP topic.

- **Database** is a PG DB.

Detailed flow diagrams are available at:

Closed Loop: https://wiki.onap.org/display/DW/Closed+Loop

Intelligent Slicing: https://wiki.onap.org/display/DW/Intelligent+Slicing+flow


Functional Description
----------------------
- Slice Analysis ms consumes PM messages from PERFORMANCE_MEASUREMENTS topic.

- For analysis Slice Analysis MS consumes various data from Config DB including List of Network  
  Functions which serves the S-NSSAI, List of Near-RT RICs and the corresponding cell mappings of the
  S-NSSAI, Current Configuration of the Near-RT RICs, Slice Profile associated with the S-NSSAI and
  Subscriber details of the S-NSSAI (for sending the onset message to policy).

- Based on the collected PM data, Slice Analysis MS computes the DLThptPerSlice and ULThptPerSlice
  for the Near-RT RICs relevant for the S-NSSAI, and the computed value is compared with the current
  configuration of the Near-RT RICs. If the change in configuration exceeds the minimum percentage
  value which is kept as a configuration parameter, then the closed-loop will be triggered by posting
  the onset message to DMaaP.

- Upon reception of recommendation to update the configuration of RAN from e.g., an ML MS, the Slice
  Analysis MS prepares and sends a control loop onset message.


Deployment aspects
------------------
The SON-Handler MS will be deployed on DCAE as an on-demand component. Details of the installation
steps are available at ./installation.rst. Further details can be obtained from:
https://wiki.onap.org/pages/viewpage.action?pageId=92998809


Known Issues and Resolutions
----------------------------
The assumptions of functionality in Guilin release is documented in:
https://wiki.onap.org/display/DW/Assumptions+for+Guilin+release