@startuml
title Intelligent Auto Healing End-to-End Sequence Diagram
Autonumber
skinparam sequenceArrowThickness 1
skinparam ParticipantPadding 5
skinparam BoxPadding 10

Box "SMO" #gold
   Participant "Non-RT RIC\n(rApps/Policies)" as nonRT
   Participant "NFO\n(NF Orchestrator)" as apiconsumer
end box

Box "O-Cloud" #lightseagreen
   Participant apiserver as "DMS\n(ETSI Profile Component)"
   Participant ms as "Monitoring System"
   Participant ns as "NF Deployment resource(s)"
End box

note over  nonRT, apiconsumer
Devtron ??
end note 

note over apiserver
Tacker 
end note 

note over apiserver, ns
StarlingX
end note

Note over nonRT, ns
  Precondition:
   - "Individual VNF instance" resource representing the NF Deployment is in INSTANTIATED state
   - Auto-healing is enabled on the "Individual VNF instance resource"
   - NF deployment is monitored in O-Cloud
   - Healing policies in non-RT RIC rApps
End Note

== Monitoring Data collection & Alarm Generation ==
Note over ns
   Failure occurs in the
   one or more of its
   virtualised resources
   or containerized workloads
   associate to the
   NF Deployment
End note
ns ->> ms: Monitoring System collects\nFault/Performanace data
ms ->> apiserver: DMS recieves fault/Performance\nTelemetry data & alarmevent generation
== Send Notification for Faulty NF Depolyment ==
apiserver ->> apiserver: Event occurs that\n matches subscription
apiserver ->> apiconsumer: Send notification about new alarm(s)\nassociated to the faulty NF Deployment
== Auto-healing (Criteria validation) of NF Deployment ==
apiserver ->> apiserver:DMS detects a healing condition that\ntriggers the auto-healing of the NF Deployment.\nE:g by monitoring alarms for faults in virtualised resources/containerised\nworkloads of the NF Deployment,along with NF Deployment-specific\nindicators (e.g., health degradation) and performance data (via PM jobs/thresholds)
apiserver ->> apiconsumer: <<O2dms>> Send VnfLcmOperationOccurrenceNotification(STARTING)
== Confirm Healing Action /Grant Request /Placement Recommendations ==
apiserver ->> apiserver: Confirm Healing Action (e.g.,terminate and create\nnew deployment item, restart a deployment item, etc.) from descriptor\nCheck granted resources,\n placement information
opt Based on "Healing action" if RIC governed Intelligent Homing/placement is needed
apiserver ->> apiconsumer:Send Grant Request
apiconsumer ->> nonRT:Send request for Placement Suggestion\nbased on operational policies
nonRT -->> nonRT: AI/ML Analysis
nonRT -->> apiconsumer:Send response\n(Placement Suggestions based on healing\homing Policies & analysis) 
apiconsumer -->> apiserver: Send Grant Response 
end
== Healing Action Implementation  ==
apiserver ->> apiconsumer: <<O2dms>> Send VnfLcmOperationOccurrenceNotification(PROCESSING)
apiserver ->> ns: NF Deployment auto-healing\n proceeds with termination,\n allocation and restart of\n necessary O-Cloud resources associated with NF deployment
apiserver ->> apiserver: NF Deployment auto-healing\n is completed
apiserver ->> apiconsumer: <<O2dms>> Send VnfLcmOperationOccurrenceNotification(COMPLETED)
Note over ns
   NF Deployment is recovered
   from the failure
End note
== Send Clear Notification for Faulty NF Depolyment ==
apiserver ->> apiconsumer: Send alarm clearance notification(s) regarding the previously faulty NF Deployment
Note over apiconsumer, ns
  Postcondition:
  NF Deployment is automatically healed and in INSTANTIATED state
End Note
@enduml