.. SPDX-License-Identifier: CC-BY-4.0
.. Copyright 2023 Nordix Foundation
.. _architecture:


Architecture
============

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Introduction
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The CCSDK ORAN components add support for handling "A1 Policies" as defined for the O-RAN A1-P interface.

The O-RAN A1-P interface is defined and specified by the `O-RAN Alliance <https://www.o-ran.org>`_


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Architecture Review
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This picture provides a overview of ONAP's A1 Controller architecture,
integration with other components and API resource/operation provided.

.. image:: ../media/ONAP-A1ControllerArchitecture.png
   :width: 500pt

The A1 Policy Management Service provides an API for accessing of A1 Policies. The A1-PMS
configures A1-Policies in RAN nodes (near-RT RICs). It also keeps a synchronized copy of these in case the A1-PMS needs to restart. 
Periodically A1-PMS will check that the configured A1 Policies and A1 Policy Types are consistent with those in the managed near-RT RICs (and take action if not).
 
Communications to near-RT RIC can be tunneled through a CCSDK/SDNC controller, using our SDNC A1-Adapter plugin.

The A1-PMS now also supports fine-grained access control checks, whereby access requests can be forwarded to an external authorization provider.

More details can be found in :ref:`developer_guide`.

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Developer Guide
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Technical information about the O-RAN components (dependencies, configuration, running & testing) can be found in :ref:`developer_guide`.