testbed/aws-powertools__powertools-lambda-python/docs/diagram_src/idempotent_sequence.puml

@startuml
'https://plantuml.com/sequence-diagram

participant Client
participant Lambda
participant "Persistence layer"


group initial request
Client->Lambda:Invoke (event)
Lambda->"Persistence layer":Get or set (id=event.search(payload))
activate "Persistence layer"
note right of "Persistence layer":Locked during this time. Prevents \nmultiple Lambda invocations with the \nsame payload running concurrently.
Lambda-->Lambda:Run Lambda handler (event)
Lambda->"Persistence layer":Update record with Lambda handler result¹
deactivate "Persistence layer"
"Persistence layer"-->"Persistence layer": Update record with result¹
Client x<--Lambda:Response not received by client
end

group retried request

Client->Lambda: Invoke (event)
Lambda->"Persistence layer":Get or set (id=event.search(payload))
Lambda<--"Persistence layer":Already exists in persistence layer. Return result¹
Client<--Lambda:Response sent to client
end

@enduml