Use a deterministic simulator to find duplicate refunds, late successes, and compensation failures.
An order reserves inventory, charges payment, then times out waiting for reservation confirmation. Cancellation begins. A late inventory success arrives after the refund. Without a state model, stock remains held or payment is refunded twice.
Define events and invariants
OrderCreated -> InventoryReserved -> PaymentCharged -> Confirmed
| timeout
v
Make compensation idempotent when its success response disappears and the triggering message returns.
Prevent overselling under concurrent checkouts: reservations vs hard decrements, SELECT FOR UPDATE, deadlock-safe multi-line…
I once shipped a checkout that charged the card the instant the customer hit pay, then ran the order...
Tune saga step timeouts, retry budgets, and compensation triggers across Java services without redeploy. Shared Kiponos tree with…
Why Pending is the safest state in payment systems. Transaction uncertainty as failure causes duplicate payments. Conservative…
Covers: Two-Phase Commit, Saga Pattern, Choreography vs Orchestration Sagas, Compensating...
