The A1 Policy Management Service consumes two ONAP APIs and the A1-P API.
DMaaP API (deprecated)
The A1 Policy Management Service API can also be accessed using ONAP DMaaP. To support this the DMaaP Message Router API is used.
Note: this functionality is deprecated, and will be removed in future versions.
O-RAN A1 Interface for A1 Policies (A1-P)
Southbound, the ONAP A1 Policy functions communicate with near-RT-RIC RAN functions using the A1 interface, as defined by the O-RAN Alliance The A1 Interface - Application Protocol Specification (A1-AP) describes this interface. The specification can be viewed from the O-RAN Alliance website.
The Kohn ONAP A1 Policy functions implement the A1 Policy parts (A1-P) of A1-AP versions v1.1, v2.0 and v3.0
An opensource implementation of a near-RT-RIC is available from the O-RAN Software Community. It supports a pre-spec version of the A1-AP. The ONAP A1 Policy functions described here also supports this A1 version (A1-OSC).