@startuml
participant REST
participant ACM_Runtime
participant Participants
database ACM_Database

REST -> ACM_Runtime: Unlock Automation Composition Instance
ACM_Runtime -> ACM_Database: Read Automation Composition Instance Information

alt Automation Composition Instance exists
 alt Automation Composition Instance administrative state is LOCKED
  ACM_Runtime -> Participants: [ASYNC] Unlock AC Element Instances for this AC Instance
  ACM_Runtime -> ACM_Database: Mark AC Instance and its AC Element Instances as Unlocking
  ACM_Runtime -> REST: Unlocking of Automation Composition Instance has been requested
 else
  ACM_Runtime -> REST: Automation Composition instance is not locked
 end
else
  ACM_Runtime -> REST: Automation Composition instance does not exist
end

@enduml