idemp.wsd

participant User
participant Application
participant Network Gateway
participant Server
User->+Application: Make Payment for $20
# Request 1
note left of Application
Client sends
payment request
end note
Application->+Network Gateway:POST /payment[Idempotency-Key:1001]
Network Gateway->+Server:POST /payment[Idempotency-Key:1001]
note right of Server
REQUEST IS NON-IDEMPOTENT
Process Payment
Respond with Confirmation
end note
Server->-Network Gateway: 200 Payment Confirmation
note left of Network Gateway
Technical difficulty unable to respond
end note
Network Gateway->-Application: 502: Bad Gateway
note left of Application
Unable to get response
try again
end note
Application->Application:Retry Request
Application->+Network Gateway:POST /payment[Idempotency-Key:1001]
Network Gateway->+Server:POST /payment[Idempotency-Key:1001]
note right of Server
{Server has already seen
Idempotency-Key:1001}
REQUEST IS IDEMPOTENT
DO NOT process payment
Repond with payment confirmation
end note
Server->-Network Gateway: 200 Payment Confirmation
Network Gateway->-Application: 200 Payment Confirmation
Application->User: Payment Successful