The CLAMP Control Loop Participant protocol is an asynchronous protocol that is used by the CLAMP runtime to coordinate life cycle management of Control Loop instances. The protocol supports the functions described in the sections below.

Protocol Dialogues

The protocol supports the dialogues described below.

Participant Registration and De-Registration

Registration when a participant comes up and update of participant with control loop type information and common parameter values for its control loop types.

De-registration is executed as a participant goes down.

Control Loop Commissioning and Decommissioning

When a control loop is commissioned, the portion of the Control Loop Type Definition and Common Property values for the participants of each participant type mentioned in the Control Loop Definition are sent to the participants.

When a control loop is de-commissioned, the portion of the Control Loop Type Definition and Common Property values for the participants of each participant type mentioned in the Control Loop Definition are deleted participants.

Control Loop Update

Control Loop Update handles creation, change, and deletion of control loops on participants. Change of control loops uses a semantic versioning approach and follow the semantics described on the page TOSCA Defined Control Loop: Architecture and Design.

The handling of a ControlLoopUpdate message in each participant is as shown below.

Control Loop State Change

This dialogue is used to change the state of Control Loops and their Control Loop Elements. the CLAMP Runtime sends a Control Loop State Change message on the control loop to all participants. Participants that have Control Loop Elements in that Control Loop attempt an update on the state of the control loop elements they have for that control loop, and report the result back.

The handling of a ControlLoopStateChange message in each participant is as shown below.

Control Loop Monitoring and Reporting

This dialogue is used as a heartbeat mechanism for participants, to monitor the status of Control Loop Elements, and to gather statistics on control loops. The ParticipantStatus message is sent periodically by each participant. The reporting interval for sending the message is configurable.

Messages

The CLAMP Control Loop Participant Protocol uses the following messages. The descriptions below give an overview of each message. For the precise definition of the messages, see the CLAMP code at: https://github.com/onap/policy-clamp/tree/master/models/src/main/java/org/onap/policy/clamp/controlloop/models/messages/dmaap/participant. All messages are carried on DMaaP.

Message	Source	Target	Purpose	Important Fields	Field Descriptions
ParticipantRegister	Participant	CLAMP Runtime	Participant registers with the CLAMP runtime	ParticipantId	The ID of this participant
				ParticipantType	The type of the participant, maps to the capabilities of the participant in Control Loop Type Definitions

ParticipantRegisterAck	CLAMP Runtime	Participant	Acknowledgement of Participant Registration	ParticipantId	The ID of this participant
				ParticipantType	The type of the participant, maps to the capabilities of the participant in Control Loop Type Definitions
				Result	Success/Fail
				Message	Message indicating reason for failure

ParticipantUpdate	CLAMP Runtime	Participant	CLAMP Runtime sends Control Loop Element Definitions and Common Parameter Values to Participant	ParticipantUpdateMap	Map with Participant ID as its key, each value on the map is a ControlLoopElementDefintionList
				ControlLoopElementDefintionList	List of ControlLoopElementDefinition values for a particular participant
				ControlLoopElementDefinition	A ControlLoopElementToscaServiceTemplate containing the definition of the Control Loop Element and a CommonPropertiesMap with the values of the common property values for the Control Loop Element
				ControlLoopElementToscaServiceTemplate	The definition of the Control Loop Element in TOSCA
				CommonPropertiesMap	A <String, String> map indexed by the property name. Each map entry is the serialized value of the property, which can be deserialized into an instance of the type of the property.

ParticipantUpdateAck	Participant	CLAMP Runtime	Acknowledgement of Participant Update	ParticipantId	The ID of this participant
				ParticipantType	The type of the participant, maps to the capabilities of the participant in Control Loop Type Definitions
				Result	Success/Fail
				Message	Message indicating reason for failure

ParticipantDeregister	Participant	CLAMP Runtime	Participant deregisters with the CLAMP runtime	ParticipantId	The ID of this participant
				ParticipantType	The type of the participant, maps to the capabilities of the participant in Control Loop Type Definitions

ParticipantDeregisterAck	CLAMP Runtime	Participant	Acknowledgement of Participant Deegistration	ParticipantId	The ID of this participant
				ParticipantType	The type of the participant, maps to the capabilities of the participant in Control Loop Type Definitions
				Result	Success/Fail
				Message	Message indicating reason for failure

ParticipantUpdate	CLAMP Runtime	Participant	CLAMP Runtime sends Control Loop Element Definitions and Common Parameter Values to Participant	ParticipantUpdateMap	Map with Participant ID as its key, each value on the map is a ControlLoopElementDefintionList
				ControlLoopElementDefintionList	List of ControlLoopElementDefinition values for a particular participant
				ControlLoopElementDefinition	A ControlLoopElementToscaServiceTemplate containing the definition of the Control Loop Element and a CommonPropertiesMap with the values of the common property values for the Control Loop Element
				ControlLoopElementToscaServiceTemplate	The definition of the Control Loop Element in TOSCA
				CommonPropertiesMap	A <String, String> map indexed by the property name. Each map entry is the serialized value of the property, which can be deserialized into an instance of the type of the property.

Control Loop Update

Control Loop Update Ack

Control Loop State Change

Participant Status