Payment Lab · Flow Explorer

What each system knows when a transaction takes an unexpected path.

A host can approve a payment while the terminal still shows UNKNOWN. Choose a scenario, step through the events, and inspect what Terminal, Middleware, Host, and Merchant honestly know at each moment. Illustrative simulation using synthetic data; retry and reversal behavior varies by scheme, acquirer, host, terminal, and contract.

ScenarioRecovery policy

Host approves; terminal never observes the response.

00+0ms
▶
·
·
·
TXN CREATED
Terminal creates sale
01+120ms
▶
◀
·
·
REQUEST SENT
Request sent to middleware
02+240ms
·
▶
◀
·
REQUEST RECEIVED
Middleware forwards request
03+360ms
·
◀
▶
·
HOST APPROVED
Host approves
04+480ms
◀
▶
·
·
RESPONSE SENT
Middleware sends final response
05+600ms
·
·
·
·
MESSAGE LOST
Terminal response lost
06+720ms
·
·
·
·
TIMEOUT
Terminal timeout
07+840ms
▶
◀
·
·
STATUS QUERY
Terminal queries status
08+960ms
◀
▶
·
·
STORED RESPONSE REPLAYED
Stored response replayed
09+1080ms
▶
◀
·
·
ACK SENT
Terminal ACK dispatched
10+1200ms
▶
◀
·
·
ACK RECEIVED
Middleware records ACK

Speed

1 / 11

What is known now?

HostNONE
MiddlewareCREATED
TerminalPENDING
DeliveryNOT SENT
Merchant visibilityPENDING
Financial dispositionNOT DETERMINED

Response to terminal lost

TXN CREATED

Terminal creates sale

A sale request is composed on the terminal. Nothing else has happened yet — no request in flight, no host contact.

Loading…