The CLAMP Runtime Server

- 1.1 Terminology
2 Design of Rest Api
- 2.1 Create of a Control Loop Type
- 2.2 Delete of a Control Loop Type
- 2.3 Create of a Control Loop
- 2.4 Update of a Control Loop
- 2.5 Delete of a Control Loop
3 Design of "issues control loop commands to control loops"
- 3.1 UNINITIALISED to PASSIVE
- 3.2 PASSIVE to UNINITIALISED
- 3.3 PASSIVE to RUNNING
- 3.4 RUNNING to PASSIVE
4 StartPhase
- 4.1 How to define StartPhase
  - 4.1.1 Control Loop Types yaml file
  - 4.1.2 Control Loop Types yaml file
- 4.2 How StartPhase works
5 Design of managing messages
- 5.1 PARTICIPANT_REGISTER
- 5.2 PARTICIPANT_UPDATE_ACK
- 5.3 PARTICIPANT_STATUS
- 5.4 CONTROLLOOP_UPDATE_ACK
- 5.5 CONTROLLOOP_STATECHANGE_ACK
- 5.6 Design of monitoring execution in SupervisionScanner
6 Design of Exception handling
7 Media Type Support
- 7.1 application/json
- 7.2 application/yaml
- 7.3 text/plain

This article explains how CLAMP Control Loop Runtime is implemented.

Terminology

Broadcast message: a message for all participants (participantId=null and participantType=null)
Message to a participant: a message only for a participant (participantId and participantType properly filled)
ThreadPoolExecutor: ThreadPoolExecutor executes the given task, into SupervisionAspect class is configured to execute tasks in ordered manner, one by one
Spring Scheduling: into SupervisionAspect class, the @Scheduled annotation invokes "schedule()" method every "runtime.participantParameters.heartBeatMs" milliseconds with a fixed delay
MessageIntercept: "@MessageIntercept" annotation is used into SupervisionHandler class to intercept "handleParticipantMessage" method calls using spring aspect oriented programming
GUI: graphical user interface, Postman or a Front-End Application

Design of Rest Api

Create of a Control Loop Type

GUI calls POST "/commission" endpoint with a Control Loop Type Definition (Tosca Service Template) as body
CL-runtime receives the call by Rest-Api (CommissioningController)
It saves to DB the Tosca Service Template using PolicyModelsProvider
if there are participants registered, it triggers the execution to send a broadcast PARTICIPANT_UPDATE message
the message is built by ParticipantUpdatePublisher using Tosca Service Template data (to fill the list of ParticipantDefinition)

Delete of a Control Loop Type

GUI calls DELETE "/commission" endpoint
CL-runtime receives the call by Rest-Api (CommissioningController)
if there are participants registered, CL-runtime triggers the execution to send a broadcast PARTICIPANT_UPDATE message
the message is built by ParticipantUpdatePublisher with an empty list of ParticipantDefinition
It deletes the Control Loop Type from DB

Create of a Control Loop

GUI calls POST "/instantiation" endpoint with a Control Loop as body
CL-runtime receives the call by Rest-Api (InstantiationController)
It validates the Control Loop
It saves the Control Loop to DB

Update of a Control Loop

GUI calls PUT "/instantiation" endpoint with a Control Loop as body
CL-runtime receives the call by Rest-Api (InstantiationController)
It validates the Control Loop
It saves the Control Loop to DB

Delete of a Control Loop

GUI calls DELETE "/instantiation" endpoint
CL-runtime receives the call by Rest-Api (InstantiationController)
It checks that Control Loop is in UNINITIALISED status
It deletes the Control Loop from DB

Design of "issues control loop commands to control loops"

UNINITIALISED to PASSIVE

GUI calls "/instantiation/command" endpoint with PASSIVE as orderedState
CL-runtime checks if participants registered are matching with the list of control Loop Element
It updates control loop and control loop elements to DB (orderedState = PASSIVE)
It validates the status order issued
It triggers the execution to send a broadcast CONTROL_LOOP_UPDATE message
the message is built by ControlLoopUpdatePublisher using Tosca Service Template data and ControlLoop data. (with startPhase = 0)
It updates control loop and control loop elements to DB (state = UNINITIALISED2PASSIVE)

PASSIVE to UNINITIALISED

GUI calls "/instantiation/command" endpoint with UNINITIALISED as orderedState
CL-runtime checks if participants registered are matching with the list of control Loop Element
It updates control loop and control loop elements to DB (orderedState = UNINITIALISED)
It validates the status order issued
It triggers the execution to send a broadcast CONTROL_LOOP_STATE_CHANGE message
the message is built by ControlLoopStateChangePublisher with controlLoopId
It updates control loop and control loop elements to DB (state = PASSIVE2UNINITIALISED)

PASSIVE to RUNNING

GUI calls "/instantiation/command" endpoint with RUNNING as orderedState
CL-runtime checks if participants registered are matching with the list of control Loop Element.
It updates control loop and control loop elements to DB (orderedState = RUNNING)
It validates the status order issued
It triggers the execution to send a broadcast CONTROL_LOOP_STATE_CHANGE message
the message is built by ControlLoopStateChangePublisher with controlLoopId
It updates control loop and control loop elements to DB (state = PASSIVE2RUNNING)

RUNNING to PASSIVE

GUI calls "/instantiation/command" endpoint with UNINITIALISED as orderedState
CL-runtime checks if participants registered are matching with the list of control Loop Element
It updates control loop and control loop elements to db (orderedState = RUNNING)
It validates the status order issued
It triggers the execution to send a broadcast CONTROL_LOOP_STATE_CHANGE message
the message is built by ControlLoopStateChangePublisher with controlLoopId
It updates control loop and control loop elements to db (state = RUNNING2PASSIVE)

StartPhase

The startPhase is particularly important in control loop update and control loop state changes because sometime the user wishes to control the order in which the state changes in Control Loop Elements in a control loop.

How to define StartPhase

StartPhase is defined as shown below in the Definition of TOSCA fundamental Control Loop Types yaml file.

Control Loop Types yaml file

startPhase:
  type: integer
  required: false
  constraints:
  - greater-or-equal: 0
  description: A value indicating the start phase in which this control loop element will be started, the
               first start phase is zero. Control Loop Elements are started in their start_phase order and stopped
               in reverse start phase order. Control Loop Elements with the same start phase are started and
               stopped simultaneously
  metadata:
    common: true

The "common: true" value in the metadata of the startPhase property identifies that property as being a common property.
This property will be set on the CLAMP GUI during control loop commissioning.
Example where it could be used:

Control Loop Types yaml file

    org.onap.domain.database.Http_PMSHMicroserviceControlLoopElement:
      # Consul http config for PMSH.
      version: 1.2.3
      type: org.onap.policy.clamp.controlloop.HttpControlLoopElement
      type_version: 1.0.1
      description: Control loop element for the http requests of PMSH microservice
      properties:
        provider: ONAP
        participant_id:
          name: HttpParticipant0
          version: 1.0.0
        participantType:
          name: org.onap.k8s.controlloop.HttpControlLoopParticipant
          version: 2.3.4
        uninitializedToPassiveTimeout: 180
        startPhase: 1

How StartPhase works

In state changes from UNITITIALISED → PASSIVE, control loop elements are started in increasing order of their startPhase.

Example with Http_PMSHMicroserviceControlLoopElement with startPhase to 1 and PMSH_K8SMicroserviceControlLoopElement with startPhase to 0

CL-runtime sends a broadcast CONTROL_LOOP_UPDATE message to all participants with startPhase = 0
participant receives the CONTROL_LOOP_UPDATE message and runs to PASSIVE state (only CL elements defined as startPhase = 0)
CL-runtime receives CONTROL_LOOP_UPDATE_ACT messages from participants and set the state (from the CL element of the message) to PASSIVE
CL-runtime calculates that all CL elements with startPhase = 0 are set to proper state and sends a broadcast CONTROL_LOOP_UPDATE message with startPhase = 1
participant receives the CONTROL_LOOP_UPDATE message and runs to PASSIVE state (only CL elements defined as startPhase = 1)
CL-runtime calculates that all CL elements are set to proper state and set CL to PASSIVE

In that scenario the message CONTROL_LOOP_UPDATE has been sent two times.

Design of managing messages

PARTICIPANT_REGISTER

A participant starts and send a PARTICIPANT_REGISTER message
ParticipantRegisterListener collects the message from DMaap
if not present, it saves participant reference with status UNKNOWN to DB
if is present a Control Loop Type, it triggers the execution to send a PARTICIPANT_UPDATE message to the participant registered (message of Priming)
the message is built by ParticipantUpdatePublisher using Tosca Service Template data (to fill the list of ParticipantDefinition)
It triggers the execution to send a PARTICIPANT_REGISTER_ACK message to the participant registered
MessageIntercept intercepts that event, if PARTICIPANT_UPDATE message has been sent, it will be add a task to handle PARTICIPANT_REGISTER in SupervisionScanner
SupervisionScanner starts the monitoring for participantUpdate

PARTICIPANT_UPDATE_ACK

A participant sends PARTICIPANT_UPDATE_ACK message in response to a PARTICIPANT_UPDATE message
ParticipantUpdateAckListener collects the message from DMaap
MessageIntercept intercepts that event and adds a task to handle PARTICIPANT_UPDATE_ACK in SupervisionScanner
SupervisionScanner removes the monitoring for participantUpdate
It updates the status of the participant to DB

PARTICIPANT_STATUS

A participant sends a scheduled PARTICIPANT_STATUS message
ParticipantStatusListener collects the message from DMaap
MessageIntercept intercepts that event and adds a task to handle PARTICIPANT_STATUS in SupervisionScanner
SupervisionScanner clears and starts the monitoring for participantStatus

CONTROLLOOP_UPDATE_ACK

A participant sends CONTROLLOOP_UPDATE_ACK message in response to a CONTROLLOOP_UPDATE message. It will send a CONTROLLOOP_UPDATE_ACK for each CL-elements moved to the ordered state as indicated by the CONTROLLOOP_UPDATE
ControlLoopUpdateAckListener collects the message from DMaap
It checks the status of all control loop elements and checks if the control loop is primed
It updates the CL to DB if it is changed
MessageIntercept intercepts that event and adds a task to handle a monitoring execution in SupervisionScanner

CONTROLLOOP_STATECHANGE_ACK

Design of a CONTROLLOOP_STATECHANGE_ACK is similar to the design for CONTROLLOOP_UPDATE_ACK

Design of monitoring execution in SupervisionScanner

Monitoring is designed to process the follow operations:

to determine the next startPhase in a CONTROLLOOP_UPDATE message
to update CL state: in a scenario that "ControlLoop.state" is in a kind of transitional state (example UNINITIALISED2PASSIVE), if all CL-elements are moved properly to the specific state, the "ControlLoop.state" will be updated to that and saved to DB
to retry CONTROLLOOP_UPDATE/CONTROL_LOOP_STATE_CHANGE messages. if there is a CL Element not in the proper state, it will retry a broadcast message
to retry PARTICIPANT_UPDATE message to the participant in a scenario that CL-runtime do not receive PARTICIPANT_UPDATE_ACT from it
to send PARTICIPANT_STATUS_REQ to the participant in a scenario that CL-runtime do not receive PARTICIPANT_STATUS from it

The solution Design of retry, timeout, and reporting for all Participant message dialogues are implemented into the monitoring execution.

Spring Scheduling inserts the task to monitor retry execution into ThreadPoolExecutor
ThreadPoolExecutor executes the task
a message will be retry if CL-runtime do no receive Act message before MaxWaitMs milliseconds

Design of Exception handling

GlobalControllerExceptionHandler

If error occurred during the Rest Api call, CL-runtime responses with a proper status error code and a JSON message error. This class is implemented to intercept and handle ControlLoopException, PfModelException and PfModelRuntimeException if they are thrown during the Rest Ali calls.

All of those classes must implement ErrorResponseInfo that contains message error and status response code. So the Exception is converted in JSON message.

RuntimeErrorController

If wrong end-point is called or an Exception not intercepted by GlobalControllerExceptionHandler, CL-runtime responses with a proper status error code and a JSON message error.
This class is implemented to redirect the standard Web error page to a JSON message error.
Typically that happen when a wrong end-point is called, but also could be happen for not authorized call, or any other Exception not intercepted by GlobalControllerExceptionHandler.

Handle version and "X-ONAP-RequestID"

RequestResponseLoggingFilter class handles version and "X-ONAP-RequestID" during a Rest-Api call; it works as a filter, so intercepts the Rest-Api and adds to the header those information.

Media Type Support

CL-runtime Rest Api supports application/json, application/yaml and text/plain Media Types. The configuration is implemented in CoderHttpMesageConverter.

application/json

JSON format is a standard for Rest Api. For the conversion from JSON to Object and vice-versa will be used org.onap.policy.common.utils.coder.StandardCoder.

application/yaml

YAML format is a standard for Control Loop Type Definition. For the conversion from YAML to Object and vice-versa will be used org.onap.policy.common.utils.coder.StandardYamlCoder.

text/plain

Text format is used by Prometheus. For the conversion from Object to String will be used StringHttpMessageConverter.

This page is not updated for Istanbul, the information below this point may or may not be correct for Istanbul.